Recent Developments in Nanotechnology-Based Biosensors for the Diagnosis of Coronavirus

Abstract

The major challenge in today’s world is that medical research is facing the existence of a vast number of viruses and their mutations, which from time to time cause outbreaks. Also, the continuous and spontaneous mutations occurring in the viruses and the emergence of resistant virus strains have become serious medical hazards. So, in view of the growing number of diseases, like the recent COVID-19 pandemic that has caused the deaths of millions of people, there is a need to improve rapid and sensitive diagnostic strategies to initiate timely treatment for such conditions. In the cases like COVID-19, where a real cure due to erratic and ambiguous signs is not available, early intervention can be life-saving. In the biomedical and pharmaceutical industries, nanotechnology has evolved exponentially and can overcome multiple obstacles in the treatment and diagnosis of diseases. Nanotechnology has developed exponentially in the biomedical and pharmaceutical fields and can overcome numerous challenges in the treatment and diagnosis of diseases. At the nano stage, the molecular properties of materials such as gold, silver, carbon, silica, and polymers get altered and can be used for the creation of reliable and accurate diagnostic techniques. This review provides insight into numerous diagnostic approaches focused on nanoparticles that could have been established for quick and early detection of such diseases.

Introduction

In the year 2020, the whole world witnessed the biggest pandemic, which affected every individual in every sector. The disease was termed “coronavirus disease” (COVID) by the World Health Organization (WHO) and is also regarded as one of the deadliest pandemics since the last century, affecting the whole world. COVID was first identified in Wuhan, China, on December 31, 2019; that is why it is called “COVID-19” [1, 2].

COVID-19 has become a leading cause of death worldwide, almost halting the socioeconomic development of the world. It was considered the third outbreak of coronavirus in the twenty-first century, which has caused serious fatalities. The other two were the Severe Acute Respiratory Syndrome coronavirus (SARS-CoV) and the Middle East Respiratory Syndrome coronavirus (MERS-CoV), which occurred in the years 2002 and 2012, respectively. The point of concern with COVID-19 is its highly transmissible nature which has reached every corner of the world within a 4–5 month span and caused serious illnesses leading to death [3].

The symptoms of COVID-19 are generally similar to those of the flu, but it was found to cause more deaths. The majority of people remain asymptomatic; however, others may have mild to serious symptoms. Initially, the disease causes fever, dry cough, sore throat, fatigue, and runny nose. Later, it can progress to pneumonia, shortness of breath, and chest pain, necessitating the hospitalization of patients in critical units. There have also been cases with no symptoms to little symptoms taking up to 14 days to appear after exposure to the virus, but even an asymptomatic person may shed the virus and make others ill [4]. Except for patients with co-morbidities such as hypertension, diabetes, and heart disease, the symptoms of COVID-19 are very non-specific in nature and cannot be used for an accurate diagnosis.

Furthermore, this is a new disease, and therefore, treatment is not available, which has created panic all around. Research and developments are currently more focused on searching for diagnosis, prevention, and treatment modalities by revisiting existing therapies and drugs.

The major challenge in today’s world that medical research is facing is the existence of a vast number of viruses and their mutations, which from time to time cause outbreaks. Also, the continuous and spontaneous mutations occurring in the virus leading to the emergence of resistant virus strains have become a serious medical hazard [5].

Coronaviruses

The family Coronaviridae, suborder Cornidovirineae, order Nidovirales, and realm Riboviria are recognized as having 39 species in 27 subgenera, five genera, and two subfamilies (Fig. 1). The International Committee on Virus Taxonomy’s Coronaviridae Study Group (CSG), a working group, defined the family categorization and taxonomy (ICTV20) [1]. SARS-CoV-2 was identified by CGS as the primary COVID-19 causal agent in 2020. As a result, the mention of SARS in the titles of all these viruses recognizes that the grouping of each virus with the prototypic virus in that species is based on phylogeny rather than clinical illness (SARS-CoV) [1, 6].

Fig. 1.

Representative 2-dimensional and 3-dimensional structures of coronaviruses

The SARS-CoV-2 virus has spherical, 125 nm-diameter virions that are characterized by 20 nm-long homotrimers of the spike protein that protrude from their surfaces and resemble a crown or solar corona. Additionally, in comparison to DNA equivalents, they are enclosed, non-segmented, positive-sense RNA viruses with low stability and great mutability. They have four structural proteins: spike (S, 150 kDa), membrane (M, 25–30 kDa), envelope (E, 8–12 kDa), and nucleocapsid, along with a large viral genome of 30 kDa (N, 45 kDa). The virus’s ability to connect to and enter its host’s cells is largely dependent on the S protein [7]. These proteins may also be used as targets for the creation of diagnostic, preventative, and therapeutic approaches.

The upper airways and lungs are the novel coronavirus's principal targets, with the gut, kidney, and vasculature as potential secondary targets. Understanding the virus' life cycle is crucial to know the many approaches to preventing virus damage to the lungs. The virus infects alveolar epithelial type II cells (AECII) from a variety of sites due to a relatively large abundance of ACEII and a favorable cellular environment [6].

Importance of Nanotechnology in Viral Diagnostics

The prompt adoption of control measures to isolate and monitor contamination was considered a benefit of detection and diagnosis as additional COVID-19 containment tools. To combat viral outbreaks, it is essential to build strong, sensitive, and sophisticated detection technologies due to the vaccine’s response and the fact that any virus spreads swiftly. Nanotechnology offers promise in this circumstance. Effectively, nanotechnology has been essential in saving COVID-19. It has already covered the market for diagnostic procedures, testing, personal protective equipment (PPE), coatings, air filters, disinfectants, and many more items [4]. A trustworthy source of information regarding nanotechnology items is the Nanotechnology Products Database (NPD), which is used in a variety of COVID-19 applications [8]. According to research, viral infectious diseases such as the human immunodeficiency virus (HIV), Ebola virus, and SARS-CoV may benefit greatly from the use of nanomaterials [9]. Nanotechnology has successfully shown that it is beneficial in treating a variety of viral infections [10, 11].

In this article, we are going to have access to the many nano-based diagnostic techniques created for the quick detection and efficient treatment of illnesses like COVID-19. The inability of small lab-scale optical microscopes to distinguish viruses due to their small size and intracellular life cycle makes virus detection particularly difficult [12]. Similar to other viral infections, SARS-CoV-2 required rapid response tests with simplified operating and effective detection limits [13]. In the early stages of this diagnosis, when no characteristic initial appearances had been seen, it was difficult to examine COVID-19 purely on clinical signs [14]. Although speedy diagnosis for significant clinical cases was not possible with whole-genome sequencing due to its lengthy sequencing time and high equipment requirements, it was incredibly accurate for the diagnosis of COVID-19 [15]. Due to its sensitivity and specificity, real-time reverse transcription polymerase chain reaction (rRT-PCR) was used in public health and clinical research laboratories during the COVID-19 outbreak to identify SARS-CoV-2 [16]. Despite this, the rRT-PCR approaches rely heavily on sophisticated machinery, skilled personnel, and a stable power source. From the clinical cases to the reporting of the results, the rRT-PCR test takes a few hours to complete. Particularly, several regions where the COVID-19 outbreak frequently occurred lacked the necessary infrastructure for reliable diagnostic services for rRT-PCR, field research, and laboratories [17].

Considering the outbreak and the urgent need for a rapid and simple procedure for COVID-19, specialists throughout the world were seriously involved in the diagnosis and treatment of the disease. An analysis of body fluids (plasma, serum, sputum, and saliva) using a serological method identified the presence of particular antigens and antibodies linked to the condition. When a microorganism or antigen enters our body, they start the invulnerable structure from scratch, and our body then releases specific antibodies to combat the antigen. IgM and IgG antibodies are both detected by anti-body testing. IgM antibodies are produced by the body as part of its initial response to a new infection, offering momentary protection. They rise for a few weeks before beginning to fall as IgG production kicks in. IgG antibodies do not become detectable until 10–12 days after the infection, although IgM antibodies might be found several days after the initial infection and then fades. IgG antibodies are stored in the body and can be quickly generated whenever the same antigen is encountered. The foundation of long-term defense against pathogens is comprised of IgG antibodies. The traditional serological diagnostic methods include radiology, sensing assays, ELISA (enzyme-linked immunosorbent assay), neutralizing test, chemiluminescent immunoassay (CLIA), and real-time RT-PCR which are most broadly utilized during COVID-19 (Fig. 2) [18].

Fig. 2.

Some traditional diagnostics methods for coronaviruses

However, sensitive and specific techniques like ELISA, RT-PCR, and others were frequently used later to validate a clinician’s postulated diagnosis. Although many of the techniques discussed here are tedious, needing purified samples and hours or days to complete the analysis, they can be combined with collecting and filter systems to create permanent checking systems that could provide guidance before a bioattack [19]. Despite the widespread use of RT-PCR-based diagnostic techniques, comprehensively planned and precise diagnostics remain limited due to the high cost and specialized staff required. Additionally, accurate measurements of the complex specimen’s nucleic acid extracts are a vital requirement for any potential RT-PCR investigation. Through the amplification process, the extraction’s reduced effectiveness may produce terrible symptoms and, as a result, some unsatisfactory diagnoses. The currently used techniques are laborious, time-consuming, call for expensive equipment, and depend on the host antibody response to produce false positives [10].

A significant and viable remedy for a pandemic like COVID-19 is the antiviral capability of metal nanoparticles (Fig. 3). NPs can interact with virus particles in vivo or in the open in a specific spatial configuration. As a result, there is an enormous promise for both nano-diagnostic and nano-therapeutic methods involving the interaction of NPs with viruses [18, 20].

Fig. 3.

Applications of nanoparticles in coronavirus diagnosis (created using biorender.com)

The need to create new, less expensive testing methods that can help with the early diagnosis of the illness cannot be overstated, however, given the large number of cases and the inherent limitations of the RT-PCR and other techniques, particularly with regard to accessibility and test cost. A lot of work has been put into developing SARS-CoV-2 detection instruments and sensors based on nanoparticles.

Therefore, it is essential to design biosensing methods that take advantage of specific characteristics of NPs, such as their high surface-to-volume ratio, quantum effects, size effects, high adsorption capacity, and reactive capacity in comparison to their bulk form. Additionally, because NPs can be easily customized in terms of size and shape, it is possible to modify or immobilize their surfaces with a variety of biological species through covalent or non-covalent bonding, improving their biosensing properties in terms of low detection limits (increased up to several orders of magnitudes), high sensitivity, selectivity, and quick response to the sample analytes [21, 22].

However, one of the greatest difficulties in developing biosensors (such as DNA/RNA) is to capture very small signals that occur between biological species (bio-receptors and analytes).

Nanomaterials can be used as labels to achieve a significant signal enhancement that is high enough to be readily detectable in order to solve this problem. By affixing the specific DNA/biorecognizing probe to metal nanoparticles (Au NPs/Ag NPs) and quantum dots (Cd/Pb), labeling can be accomplished [21, 23, 24].

Nanoparticles in diagnostics can be classified as organic (quantum dots and polymeric nanoparticles) or inorganic (gold nanoparticles, silver nanoparticles, and silica nanoparticles) (Table. 1).

Table 1.

Various detection techniques using various nanoparticles

S.No.	Nanoparticles	Virus	Sensor mechanism	Limit of detection	Reference
1	AuNPs	Hepatitis—C virus (HCV)	Colourimetric detection	50 copies/reaction	[25]
2		Amplification and Silver Staining (NIASS)	Anti-HCV antibodies	10 mL N/A < 40 min	[26]
3		Human influenza virus type—A	Colorimetric	One pg RNA (10 − 3 dilution of the Viral cDNA)	[27]
4		SARS-CoV-2	Colorimetric	1 ng/mL colorimetric change observation within 5 min	[28]
5		SARS-COV-2	Raman Spectrometer	4 Picograms (pg) per mL	[29]
6		MERS-CoV	Electrochemiluminescence	1.0 pgml−1	[30]
7		HCoV	Electrochemiluminescence	0.4 pgml−1	[29]
8		Bio-AuNPs hybrid structures	-	-	[12]
9		IBV	Chiroimmunosensing	47.91 EID/50 ml	[30]
10		PEDV Porcine Epidemic diarrhea Virus	Nano-nest PCR	2.21 × 10−7ngμl−1	[31]
11		IBV	ICS	104.4 EID/50 ml	[32]
12		Influenza—A Virions	-	-	[33]
13	AgNPs	MERS-CoV	Colorimetric	1.53 nM	[34]
14		Influenza Virus	Electrostatic forces	SERS detection mechanism	[35]
15	MoS2 nanosheets	IBV	Immunosensing	4.6 × 102 EID50 per ml	[36]
16	Functionalized MNPs	SARS-CoV-2	-	0.084 nM (5.9 fmole)	[37]
17	Magnetic NPs	Genetic material (Bacteria or Virus)	Electrostatic forces PCR	-	[38]
18	ZrNPs QD-MP NPs	IBV	Photoluminescence	79.15 EID/50 ml	[39]
19	Magnetic Microparticle based immunoassay (Architect HIV Ag/Ab Combo)	HIV-1 p24 antigen	Chemiluminescent	below 2 IU/ml	[40]
20	Nanometer-scale antibody array-based analysis	HIV p24 antigen	AFM detection	1 mL	[41]
21	Nanoparticle-based bio barcode amplification assay	HIV p24 antig	100 mL	100% > 120 min	[42]
22	Nanospheres and immunomagnetic separation	Ebola Virions	Electroluminescent	200 mL N/A 2 h	[43]
23	nano-gold labeled oligonucleotide probes	Hepatitis—E Virus HEV RNA	Array-based nanoamplification and silverstain enhancement	100 mL N/A 20–30 min	[44]

Gold Nanoparticles

Due to their photonic, electrical, and catalytic capabilities, gold nanoparticles (AuNPs) have dominated investigations aimed at viral detection [12]. AuNPs are frequently used in the detection of toxins, viruses, and bacteria. Gold nanoparticles can be used to create effective biosensing stages due to their biocompatibility, chemical feasibility, large surface-to-volume ratio, size-dependent optical characteristics, and ease of surface modification [45]. Even at quantities of 1 nanogram (ng) per mL for COVID-19 antigen and 1000 virus particles per mL for SARS-CoV-2 spike protein pseudo typed baculovirus, the gold nanoparticles facilitate faster detection of antigen or virus by the naked eye [28].

AuNPs have a size range of 2–100 nm and exhibit the localized surface plasmon resonance (LSPR) phenomenon. LSPR has outstanding optical absorption qualities suitable for sensing changes close to the surface of AuNPs. The term “gold nanocluster” is used to distinguish between materials exhibiting fluorescent and plasmonic signals. Gold nanocrystals less than 2 nm in size can also be fluorescent. The majority of the literature on gold species-based sensing and detection is dominated by plasmonic effects (and subsequently, AuNPs). Because AuNPs can be coated with reactive ligands, covalent modification chemistries can be used to connect biomolecules (DNA, antibodies, proteins, etc.), such as maleimide-thiol, NHS-ester, cycloaddition (click) science, and carbodiimide coupling (EDC), in addition to non-covalent (such as biotin or NTA) or passive adsorption [19]. In areas affected by a pandemic, this low-cost detection test will be of exceptional benefit. Thus, the creation of AuNPs-based assays will result in the creation of quick, accurate, affordable, intuitive, and direct diagnostic tools for unamplified nucleic acid extracted from human specimens [46].

Two main methods are generally used in the colorimetric detection of viruses using AuNPs:

1. Color amplification technique in which AuNPs are applied to go about as immediate coloring labels with their characteristic, intense red color, and

2. color change technique in which a color change from red to purple occurs in response to particle aggregation [12].

Surface-modified thiol probes that hybridize with the target have been used to functionalize gold nanoparticles in order to stop the particles from aggregating with salt and thus altering color. It is possible to modify this stage to coincide with the end of other infectious disorders, such as COVID-19 [47].

Quantum dots (QDs) and AuNPs used in virus-mediated peptide-linked nanocomposite fluorescence quenching achieved a recognition detection limit of 17.02 fg/mLL [48]. For instance, certain gold-functionalized thiolated probes may frame the target’s disulfide bonds with complementary RNA. This was a potential colorimetric assay for the detection of MERS-CoV [49]. A selective assay has been developed that allows for the 10-min detection of SARS-CoV-2 using a UV–Vis spectrophotometer and the naked eye. The assay uses gold nanoparticles coated with thiol-modified antisense oligonucleotides (ASOs) to detect particular surface plasmon resonance alterations near the N gene. SARS-CoV-2 indicates the specific aggregation of coated nanoparticles brought on by the breakdown of the hybrid RNA chain, resulting in the formation of a precipitate that can be seen [50].

One colorimetric assay, for instance, used gold nanoparticles that were supplemented with the MERS-CoV E protein and were protected by self-assembled double-layer DNA strands [49, 51]. The addition of a green fluorescent protein to these gold nanoparticles improved their color contact and absorption when used with a complementary antibody, enabling the quantitative detection of SARS-CoV. Gold nanoparticles coupled to a monoclonal antibody were utilized as a reagent for identifying another COVID, the Porcine Epidemic Diarrhoea Virus, in an immunochromatographic analysis of pig feces samples (PEDV) [52]. They were also used as a coating over carbon electrodes immobilizing the recombinant spike protein S1 in a potentiometric immunosensor for the detection of MERS-CoV [29]. Utilizing the photothermal therapy (PTT) and LSPR, a sensitive dual-functional gold nanoisland (AuNIs)-based sensor with a detection limit of 0.22 pm has been created. The sensor demonstrated that interferometry was successfully used to identify a specific gene sequence [53].

The detection of immunoglobulin M (IgM) and immunoglobulin G (IgG) SARS-CoV-2 virus antibodies in human blood within 15 min, which can be detected at different phases, was made possible by the development of a quick and simple point-of-care lateral flow immunoassay. Additionally, analysis was completed for clinical diagnosis results derived from various venous and fingerstick blood sample types. The findings showed that fingerstick blood, serum, and venous blood plasma samples had great detection consistency. The usefulness and sensitivity of the combined IgM-IgG assay are higher than those of a single IgM or IgG test. It can be used to quickly screen SARS-CoV-2 carriers who are symptomatic or asymptomatic in medical facilities, clinics, and research facilities [47].

Using anti-spike antibody-attached gold nanoparticles, COVID-19 antigen colorimetric diagnostics can be completed in under 5 min. Antibody-attached GNPs aggregate in the presence of COVID-19 antigen due to the antigen–antibody interaction, forming a number of “hot spots” in the ESI, which is the basis for SERS-based diagnosis of COVID-19 antigens. It is now well established that “hot spot” production, which results from a strong light-matter interaction via a plasmon-excitation coupling, is a crucial aspect in providing an amazing amplification in SERS [28].

Companies were creating quick “IgM/IgG antibody assay kits” for COVID-19 and AuNPs-based strips, including the World Nano Foundation (WNF) and MIT Spin Out; the strips are wrapped in antibodies (Abs) that engage the SARS-CoV-2 virus’s viral particles (viral antigen). A color reaction will happen if a viral antigen is present in the sample (such as blood or urine). When the patient’s sample was placed on the strip, a colored spot formed if the sample contained the viral antigen, which binds to both antibodies (Fig. 4) [54].

Fig. 4.

Gold nanoparticles-based flow strips for detection of COVID-19 antigens/antibody

A nanorod based lateral flow test for coronavirus evaluation was created by Sona Nanotech Inc. of Canada, and it is anticipated to provide results in 5 to 15 min. An immunochromatographic assay for the qualitative detection of the spike protein antigen from SARS-CoV-2 in nasopharyngeal (NP) swabs from persons who were suspected of having COVID-19 is produced using Sona’s quick antigen test in around 15 min. The test was designed for use by professionals [55].

Silver Nanoparticles

The optical characteristics of silver (Ag) NPs are the same as those of AuNPs. Silver NPs have typically been used in the SERS approach in conjunction with various metal nanoarrays, which may have the potential to boost the plasmonic effect. By using electromagnetic fields and plasmonic techniques to direct Raman labeling with dynamic components, several viruses, including HBV, can be detected with detection limit of 50 aM. Prior to COVID-19, a fluorescence upgrade technology based on silver nanoparticles (AgNPs) aggregates was developed for detecting hepatitis B virus DNA successions [56]. AgNPs have been studied using hybrid tests and recognition probes (Cy3-test) (Oligomer-A and Oligomer-B). Within view of the target DNA, the functionalized AgNPs and immobilized capture probes produced complexes and other AgNPs aggregates. It exhibits linearity between 100 fM and 10 nM and has a limit of detection (LOD) of 50 fM. Additionally, this method was very selective and could detect target DNA even when genomic DNA was interfering. The high-throughput scientific potential of this fluorescent microarray could be used to diagnose a variety of other illnesses (viruses) [47, 56].

A colorimetric probe for the detection of the Middle East Respiratory Disorder Corona Virus (MERS-CoV), Mycobacterium tuberculosis (MTB), and Human Papilloma Virus (HPV) was also created using aggregated silver nanoparticles stabilized by citrate (AgNPs). It utilized a colorimetric paper-based test for DNA detection that was based on the aggregation of nanoparticles caused by the pyrrolidinyl peptide nucleic acid (acpcPNA). The DNA-pyrrolidinyl peptide nucleic acid (acpcPNA) assay produces an accumulation of citrate anion-stabilized silver nanoparticles (AgNPs) without complementing DNA due to a single positive charge from the lysine at the C-end. Within the visual range of the target DNA, a discernible color change was observed as a result of the formation of the acpcPNA duplex, which causes the AgNPs to scatter due to electrostatic repulsion [34]. The suggested paper-based colorimetric DNA sensor could be a different strategy for straightforward, quick, sensitive, and targeted DNA detection.

Carbon-Based Nanomaterials

Biosensors based on carbon nanomaterials can be used to diagnose, monitor, develop a therapeutic approach, and treat patients without causing them any pain. Due to the unmatched combination of optical, electric, and mechanical properties found in carbon nanomaterials, miniaturized sensors with superior functionality and low power consumption are produced. These nanomaterials exhibit high strength-to-weight ratios, great electron mobilities, and thermal stability in natural settings. For usage in salivary-dependent detection, carbon nanomaterials such as carbon dots (CDs), carbon nanotubes (CNTs), graphene, graphene oxide (GO), reduced graphene oxide (rGO), and graphitic carbon nitride (g-C3N4) have been highlighted with recent examples. Numerous clinically important substances, including glucose, hormones, amino acids, viruses, bacteria, cancer antigens, cancer biomarkers, dopamine, salicylic acid, uric acid, and others, can be detected by these sensors. Because of this, the cutting-edge developments covered in this analysis study have a lot of potential for using carbon nanomaterials to quickly screen people [57].

Quantum Dots

Compared to plasmonic nanoparticles that can be turned, quantum dots (QDs) are crystalline clusters with tunable optical wavelengths that are nanometer in size (1–10 nm) (10–300 nm). QDs have since been developed as a novel fluorescent molecular imaging probe [58]. QDs have broad absorption spectra, but their emission bands are small and extremely symmetric, with entire widths at the half maximum of 25–35 nm. The emission bands will range in wavelength from ultraviolet to infrared depending on the size of the dot (365–1350 nm). These materials often have high absorption cross sections and long fluorescence lifetimes (> 10 ns) [59]. QDs, also known as “semiconductor nanomaterials,” are samples that are highly fluorescent and crucial for the detection and long-term imaging of a variety of cell activities. They are created utilizing a variety of semiconductor materials [60]. Since their development, carbon QDs have drawn increased study attention because of their attractive features, which include minimal cytotoxicity, bio-compatibility, inertness, photostability, simpler manufacturing, and functionalization, among others [61, 62].

Along with the recently created antibacterial nanomaterials, graphene and carbon QDs have a wider application for microbe biosensing and can be employed as an alternate technique of medical diagnosis. Additionally, taking into account potential biocompatible carriers will enhance interdisciplinary research and enable more successful approaches to combat the virus. The development of quantum dots as a potential weapon against COVID-19 [63]. An ultrasensitive biosensor built using carbon dots and gold nanoparticles and based on the fluorescence resonance energy transfer concept was sufficient for identifying HIV DNA. The inquiry produced successful outcomes for the real-sample analysis [64]. Therefore, it is possible to examine this method for the detection of viral RNAs.

For the first time in published research, BAI et al. (2011) used carbon dots to identify DNA. Carbon dot fluorescence was discovered to be remarkably resistant to methylene blue. However, the growth of ct-DNA restored the fluorescence of carbon spots because DNA can bind to methylene blue and remove it from carbon dots. This technique can identify ct-DNA at 1.0 × 10–6 mol/L of quantification [65]. Future developments are also expected to bring about rather well-liked RNA detection probes. HIV DNA can be detected in organic samples using a sensor made of fluorescent carbon dots and cadmium telluride quantum dots coated with 3-mercapropionic acid. This probe enables ratiometric measurements of double-stranded DNA.

To detect bacteria and biomolecules, carbon QDs now dominate imaging tests (chemosensors and biosensors). In contrast to conventional testing methods, carbon QDs and an ultrasensitive lateral flow immunoassay technology have been proven to be highly explicit at detecting influenza A virus subtypes [65]. Essentially, chiral zirconium QDs with blue fluorescence output were used to sense the irresistible bronchitis virus [66]. Additionally, single HIV-1 genes in human chromosomes have been identified using live-cell imaging and QDs in combination with effectors similar to record activators (Fig. 5) [67]. According to Liu et al. (2017), CDs made from young barley leaves that have been pulverized exhibit distinct fluorescent hues like blue (bCDs) and cyanin (cCDs), which have been employed for specific cell imaging. While the cCDs are dispersed throughout the entire cell and in the nucleus of PK15 cells, the bCDs can only selectively penetrate the cytoplasm of these cells [68]. The long SARS-CoV N protein has 422 amino acid residues, and semiconductor quantum dots paired with RNA oligonucleotide have shown sensitivity to this protein and the ability to assess potential inhibitors using a biochip [69]. Anti-infectious antigenic virus (IBV) antibodies have been synthesized into zirconium quantum spots, allowing for the detection and concentration of additional magnetoplasmonic antigenic anti-IBV conjugated antibodies [38].

Fig. 5.

Schematic representation of the actions exerted by QDs on SARS‐CoV‐2. QD, quantum dot; S protein, spike protein; SARS‐CoV‐2, severe acute respiratory syndrome coronavirus type 2

Graphene Nanoparticles

A nanomaterial with thousands of advantages is graphene. Although there are a number of opportunities to use in vivo graphene and its composites against COVID-19, the demand for drugs and antibodies to treat SARS-CoV-2 is much more urgent than we anticipated due to the lack of a thorough hazard characterization. Prioritizing personal security information for front-line healthcare workers could be done with graphene face-mask coatings. Future allies of pandemic-prevention frameworks are applications of graphene materials for epidemiological transparency, positioning, and sifting. Additionally, successful demonstrations of graphene-based high-throughput diagnostics and drug screening have been made, and several of these sensors have started to move toward commercialization [70]. Though additional research is needed, it is anticipated that graphene will be crucial in the global effort to combat COVID-19. For on-site detection of the SARS-CoV-2 virus, a field-effect transistor (FET) based on graphene has been used. Given the low cost of graphene materials, antibody-conjugated graphene sheets can be useful for the construction of environmental sensors and filters as well as for the quick detection of specified viral proteins in huge populations. When paired with heat- or light-mediated inactivation, functionalized graphene has shown a strong ability to trap viruses, making it potentially useful as a disinfectant. It is interesting to note that the SARS-CoV-2 spike S1 protein receptor-binding domain has been shown to interact with heparin and modify conformation. Graphene’s ability to absorb light can be employed to eliminate virus particles after capture. The herpes simplex virus type 1 (HSV-1) has been successfully captured and photo-thermally destroyed using sulfonated magnetic nanoparticles functionalized with rGO. These findings demonstrate how GO capture and NIR lung therapies may be combined. It is true that absorbents like graphene and GO are in the NIR tissue transparency window and enable the deep penetration of incoming light in the body, as demonstrated for the treatment of lung metastases [71].

Magnetic Beads/Nanoparticles

One of the most promising methods for swiftly and accurately identifying biomolecules is homogeneous biosensing based on magnetic nanoparticles (MNPs). To provide a strategy for the quick and sensitive positioning of SARS-CoV-2 with functionalized MNPs, the calculation of their attractive reactions in an air conditioner field was used. The theory was tested in studies using a fake SARS-CoV-2 constructed of polystyrene beads and spike proteins. According to preliminary results, the suggested technique enables the quick discovery of copy SARS-CoV-2 with a position constraint of 0.084 nM (5.9 fmol). The suggested strategy has amazing promise for developing a low-cost, point-of-care device for quick and accurate SARS-CoV-2 testing [37].

Silica-Coated Superparamagnetic Nanoparticles

Silica-coated superparamagnetic nanoparticles were employed at various phases of polymerase chain reaction (PCR) experiments to recognize SARS-CoV genetic sequences [72]. Additionally, the PEDV film protein-targeting single domain antibody-labeled ZnS-covered CdSe quantum dots were used to photograph the Vero cell viruses [73].

Another area of convergence for nanotechnology applications is the extraction of viral RNA, which is now frequently employed in conjunction with atomic diagnostics. It has been proven that silica-coated nanoparticles may quickly extract RNA from virus-intolerant samples for RT-PCR detection later [74]. This makes the process more delicate while also reducing the requirement for delayed RNA extraction. Another significant consideration is the employment of crossbreed structures, a widely utilized technology in the creation of sensors that coordinates the use of biomolecules produced from viruses with nanostructures [12, 75].

Zinc Ferrite Nanoparticles

In order to facilitate prospective COVID-19 extraction and RT-PCR based detection, a more advanced and uncomplicated MNP-assisted RNA-extraction convention was suggested. The cost-effective sol–gel auto-ignition approach was used to create the zinc ferrite (ZNF) MNPs, and subsequently, the surfaces were functionalized with carboxyl containing polymers. Due to its high substance dependability, delicately attractive behavior, ease of preparation, and bio-compatibility, zinc ferrite was selected as one of the most alluring materials. Due to the strong interaction between nucleic acids and carboxyl groupings, the surface-functionalized MNPs promote quick and predictable viral RNA adsorption. Due to its simplicity and cleverness, this method might be an excellent replacement for traditional ones. In order to identify COVID-19 and other disorders, quick, catalytic, and automotive approaches for nucleic acid extraction are essential. Zinc ferrite nanoparticles were produced via combustion synthesis and functionalized with silica and carboxyl modified polyvinyl alcohol. To verify their existence and fictionalization at the nanoscale, the MNPs were identified. The suggested model might be able to automate the extraction of viral RNA from various specimens [20, 76].

Nanopore

The fourth-generation DNA sequencing method known as “nanopore sequencing” has a number of benefits, including ultra-long reads (104–106 bases), biological or solid-state nanopores, high throughput, and minimal material requirements. All of these rely significantly on experimentation and are easily applicable to DNA sequencing applications. The breakthrough in nanopore sequencing, which is also the most amazing method for the rapid aging of long-read sequences, was created by Oxford Nanopore Technologies Ltd. Nanopore sequencing eliminates the requirement for PCR enhancement or chemical labeling of the material and allows for the sequencing of a single DNA or RNA molecule. With the potential to present continuous results in real time, high testing versatility, and quick test preparation, nanopore sequencing may offer genotyping at a comparatively low cost. In order to move a difficult-to-transfer sample through a 10–9 m diameter opening during nanopore sequencing, electrophoresis is required [77].

It has been demonstrated that the nanopore metagenome method may effectively distinguish clinical samples from respiratory viruses and bacterial diseases. It is significantly quicker than the conventional culture approach to identify microorganisms and anti-toxin blockage properties [78]. Similar to how full-length genomic RNA COVID was treated, arrangements in the SARS-CoV-2 transcriptome were treated using nanopore sequencing [79]. These investigations revealed a greater range of viral records and a favorable evaluation of transformational effects when RNA was altered. These findings provided encouraging estimates of the transformational Corona virus rates as well as a wider variety of viral recordings with RNA changes. However, direct RNA sequencing and metagenome sequencing approaches enable unbiased arrangement investigation since viral nucleic acids are substantially less abundant in clinical samples than host nucleic acids. In recent studies, the ARTIC technique has been used to extract the full SARS-CoV-2 genome from virus isolates or clinical samples in place of tiling multiplex PCR, which has been used to study Zika and Ebola. Faster genomic observation of SARS-CoV-2 and a deeper comprehension of its pathogenicity, growth, and transmission are made possible by the effective accumulation of the entire typical genome that may be obtained by looking at the covers between multiplex amplicons. Sequencing is insufficient for clinical judgment and SARS-CoV-2 identification. In any event, these recently established procedures rely on nanopore sequencing for clinical conclusion and identification of SARS-CoV-2 due to the enormous number of clinical cases and the requirement for a quick turnaround time [80].

Because it involves the straightforward direct sequencing of DNA and RNA on a relatively portable device, the Oxford Nanopore MinION (and related inventions) disrupt other large-scale sequencing processes. The benefits of such a development in spotting quickly spreading infections were clearly seen during the West African Ebola outbreak. It was used to keep track of flare-up developments and describe pollution. Additional developments will greatly reduce the cost and accelerate sequencing. One such technique is amplicon-based sequencing, in which a PCR primer set is used to enhance a specific region of a genome or chromosome, and the amplicons that result are then sequenced. This method offers a fantastic tool for quickly determining and assessing the presence of viral microorganisms in clinical samples when paired with the MinION [80].

Meanwhile, other respiratory viruses can result in fever and pneumonia. Cross-infection during the analytic encounter leads to the spread of SARS-CoV-2 and exposes COVID-19 patients to additional respiratory viruses. In actual situations, a detailed examination of the infecting viruses is required. Furthermore, despite the frequent execution of several SARS-CoV-2 tests around the globe, the information gleaned from these techniques can only be applied to later virulence and mutation analyses, as well as epidemiological research. The majority of current approaches to understanding virus succession rely on high-cost, low-throughput whole genome sequencing methods. For the prevention and management of COVID-19, observable evidence of harmfulness modifications, virus makeup, and epidemiological research are all crucial. A quick, dependable, and thorough identification technique is therefore required to highlight clinical problems and check for cross-contamination to reduce mortality [81]. The creation of a nanopore was centered on the next-generation sequencing (NTS) stage for the identification of SARS-CoV-2 and its final resting place. Within 6–10 h, it can recognize other respiratory viruses, the screen-changed nucleic acids, and identify other respiratory viruses while combining the advantages of targeted amplification with those of long read, continuous, high sensitivity nanopore sequencing [81].

Polymeric Nanoparticles

The invention of a pcMNPs-based viral RNA extraction technique and the combination of poly (amino ester) and magnetic nanoparticles (pcMNPs) covered with carboxyl groups for the sensitive detection of COVID-19 SARS-CoV-2 virus. The pcMNPs-RNA structures can be directly incorporated into the RT-PCR responses using this technique since it integrates the lysis and restriction processes into a single phase. Either a straightforward manual method or a mechanized high-throughput technology, the worked-on cycle can clean typical RNA from several samples in 20 min. A sensitive and persistent linear association between 10 and 105 duplicate SARS-CoV-2 pseudovirus particles can be established by differentiating two separate regions (ORF1ab and N genes) of viral RNA. With its excellent proficiency and ease of use, this new extraction technique can drastically cut the turnaround time and operational requirements of the current COVID-19 molecular diagnosis, especially for early clinical diagnosis [74].

Recently, a single test tube test with one step was created employing polymeric nanoparticles made with streptavidin. The test was centered on reverse transcription loop-mediated isothermal amplification along with a nanoparticle-based biosensor for SARS-CoV-2 discovery (RT-LAMP-NBS). RT-LAMP-NBS COVID-19 has a good level of specificity, sensitivity, and feasibility for the SARS-CoV-2 position. The target assay is a helpful diagnostic tool that can be used in primary health care facilities, hospitals, and public health settings. During clinical preliminaries in COVID-19 patients, the test supposedly had 100% analytical sensitivity and specificity [82]. Typically, human nasopharyngeal swabs or spit samples were tested for viral nucleic acid or antigen in order to identify patients with the early illness. Using a spike protein explicit nanoplasmonic reverberation sensor, a method was devised for the rapid and direct optical quantification of SARS-CoV-2 virus particles in a single step, essentially without any sample preparation. The virus’s centralization may be immediately evaluated in the region of 0 to 107 vp/mL, and at one point, 370 vp/mL was found in 15 min. According to estimates from the generic microplate reader and the handheld smartphone-connected device, both routine clinical settings and resource-constrained settings can easily achieve speedy detection [14].

Immunodiagnostic methods that are quick and simple are crucial for identifying positive cases. Lanthanide-doped polystyrene nanoparticles have been used in research to develop a rapid and accurate horizontal stream immunoassay for the detection of anti-SARV-CoV-2 IgG in human serum. A nitrocellulose substrate was treated with capture-specific IgG and a recombinant SARS-CoV-2 nucleocapsidphosphoprotein. The fluorescent nanoparticles that were self-collected were named after the mouse anti-human IgG counteracting agent. This test required a 100-L aliquot (1:1000 weakening) of serum samples, and the entire discovery procedure lasted 10 min. The results of the approval research satisfied the criteria for symptomatic clinical reagents. The cutoff confidence was determined to be 0.0666 after looking at 51 common examples. Seven reverse transcriptase PCR (RT-PCR) samples that were positive and twelve that were negative but had clinical suspicion were examined for anti-SARS-CoV-2 IgG antibodies. SARS-CoV-2 IgG positive was one of the negative examples, but the discoveries for other criteria were valid with those obtained by RT-PCR. This test will accurately and promptly detect anti-SARS-CoV-2 IgG in human serum and positively identify fluorimetric lanthanide-doped polystyrene nanoparticles [83].

Nanostrips

Nanotechnology-based flow strip tests may be used in the field to categorize the Corona virus. As a clear point-of-care test for IBV disease in hens, monoclonal antibodies are immobilized through a support network containing unlabeled antibodies coupled to gold nanoparticles and confined to the antigen of concern, such as the resistant chromatography strip [83].

An up-conversion nanoparticle (UCNP) bedside position system based on fluorescent nanostrips was developed using immunoglobulins [10]. An immunochromatography system based on colloidal gold (LOD-1000 pg/mL) and localization techniques based on the principle of antigen limitation to neutralizer-coated NPs were used to construct biosensors [84].

The study concentrated on various restrictions and problems with using NPs to treat and examine COVID-19 viral contaminations. For instance, in some nations, the diagnosis and treatment of viral diseases are expensive, insufficient, remote, and unaffordable. Because of the virus’s unusual behavior and intricate viral metabolic processes [85], it can be challenging to create a successful administration protocol. But if the SARS-COV-2 virus shares a genetic step with the flu virus, this could be a limiting development in curbing viral propagation [86]. Due to problems with nanotoxicity, the commercialization of functionalized NPs is still restricted [87]. NPs could result in unfavorable effects such as nanotoxicity, inflammation, genotoxicity, oxidative damage, and, last but not least, pneumonic fibrosis via disrupting the respiratory system [86]. Additionally, NPs have a number of drawbacks, including a low conveying capacity, a high price, and assembly problems. Finally, the interaction of metallic NPs with SARS-CoV-2 has been overlooked. Therefore, for effective and practical viral contamination control, raising the safety concerns of nano-based techniques by supplying a standard “safety evaluation” appraisal during the functionalization of NPs is required [2]. An interdisciplinary stage is also required to support the clinical interpretation of the nano therapeutics-based method to battle viral contamination [46].

Nanowires

The identification of viruses or perhaps the early diagnosis of cancer may be possible with silicon nanowires. Due to their tiny size, even a single molecule could create discernible variations in conductivity. They are becoming quite well known despite their exorbitant price [88]. Incorporating silicon nanowires with RT-PCR sensors on the silicone innovation stage, according to Zhang et al. (2010), may improve outcomes [89]. The sensor based on silicon nanowires is incredibly quick and sensitive for the detection of Dengue Serotype 2 (DEN-2). The surface of the nanowires was covalently attached to a specific peptide nucleic acid (PNA). A comparable DEN-2 (69 bp) segment was produced using one-step RT-PCR amplification and added to the SiNW functionalized with PNA substance. By comparing the resistance change of the SiNW before and after the RT-PCR product of DEN-2 bound to the PNA sequence, the hybridization event was confirmed. The SiNW sensor could distinguish amplicons that were smaller than 10 fM within 30 min. These nanoscale devices are therefore extremely sensitive for the quick detection of viruses.

Nano Barcodes

Nanobarcodes (NBs) are submicron sized metallic nanowires with sections of Ag and Au that are created by electroplating the inert metals onto alumina templates one at a time. Striped nanowires are left over when the template is destroyed. By analyzing the reflectance of the areas when irradiated with blue light, it is feasible to differentiate the Ag and Au sections of the nanowires (400 nm). Due to their confidentiality and ability to simultaneously analyze several targets, NBs have been used advantageously for bioimaging due to their nanoscale dimension(s). The optical (fluorescent and non-fluorescent), graphic, magnetic, and phase change capabilities of nanoparticles or their various shapes and sizes are some of the encoding elements that are based on the encoding methodologies to build unique multiple codes for NBs. To create the NBs, these encoding components are often incorporated inside nanostructures, ornamented on their surfaces, or self-assembled. Each encoding method has a distinct decoding method that must be suitable for the intended applications. Due to their simplicity and high visibility, optical NBs based on fluorescence are the most often used techniques. For the multiplexed detection of B. anthracis, Ebola, and SARS, DNA-based fluorescent NBs with various ratios of green and red fluorescence probes have been utilized. Fluorescent DNA barcodes have also been used to investigate single-cell expression. Additionally, the detection of HIV, hepatitis C virus, and SARS DNA has been demonstrated using Au/Ag nanowires [59].

With the magnitude and resulting overflow of NPs, many researchers expand on previously validated immunogenic tests. This expedites the study process. Combining diagnostics and mobile phones can lead to more effective communication and reconnaissance. Given this, diagnostics are a crucial component of the flare-up management toolkit because they enable medical professionals to focus resources and efforts on patients who are infected with illnesses like COVID-19. This cycle will lessen mortality and slow the spread of contagious bacteria. Others employ NPs as a tool to deal with natural cases in order to obtain lower position limitations than what could be accomplished using conventional methods in a comparable amount of time. Whether or not the assortment of NP identification and type biochemicals presented here makes a strong case for their continued advancement and expanded use to satisfy the requirements for the bio-specialist position in research facilities, fields, or complex lattices, it is still a small portion of what has been successfully used or even tested.

Future Aspects and Challenges

The COVID-19 pandemic was a terrifying threat to human societies all over the world, but it should also be seen as a chance to remind our international community that multi- and inter-disciplinary approaches, encouraging diversity in the creation of problem-solving groups, and the exchange of expertise between countries would all be crucial to achieving new and crucial scientific solutions. By creating biosensors to identify the virus in its earliest stages of infection, preventing its transmission using nanocomposites that can also be used to disinfect public medical devices, and ultimately utilizing vaccines to provide immunity against transmission, nanotechnology is expected to play a critical role in the fight against COVID-19.The optical and magnetic characteristics of various NPs can be utilized in the creation of diagnostic test kits. However more investigation is necessary for early and rapid virus detection [90].

Furthermore, it has been effectively established that integrating NPs into affinity-based biosensing systems enables quick, sensitive, and trustworthy detection of SARS, MERS, and COVID-19. The development of advanced biosensor performances, including high sensitivity, selectivity, and low detection limits, was made possible by nanomaterial-based biosensors. The creation of an immunosensor and a DNA-sensor for MERS and COVID-19, respectively, had used silicon and gold nanoparticles with success. The potential for shrinking into low-cost, integrated systems that operate similarly to handheld electrochemical readers is a key characteristic of nanobiosensors. Despite these promising qualities, only a small number of samples of nanobiosensors detection have been created and successfully used in actual clinical investigation to far. The ones that are marketed are thin membrane strips that resemble paper and are covered with antigens in the nitrocellulose membrane and gold nanoparticle-antigen conjugates in the conjugation pad [91].

Moving ahead, artificial intelligence (AI) has had a greater impact on the COVID-19 infection identification in medical pictures (chest X-rays and CT scans), contact tracking, and evidence-based policymaking compared to the SARS-CoV-1 outbreak in 2003. Technologies that support artificial intelligence, such as the AI robot, smart toilet, and smartphone, may be a great resource for tracing, diagnostics, and therapies. The smart toilet could play a key role in the diagnosis of COVID-19 since it is a non-invasive instrument that can collect and analyze feces and urine. The robot can operate in hazardous conditions, alleviating the strain on the front-line medical workers. The AI robot is equipped to take throat samples. In crowded public areas like customs, airports, ports, and train stations, the diagnostic and service robots will be used. Ideally, as AI technology continues to advance, robotics will become smarter and more potent [92]. Asymptomatic and discharged COVID-19 patients are more prone to spread the illness to people who are in close proximity, making epidemic prevention and control difficult and necessitating long-term tracking and monitoring. Another evidence of the high demand for ultrasensitive diagnostic procedures is the virus identification in urine and stool samples of certain confirmed patients, including asymptomatic cases. A promising read-out platform is a smartphone with various optomechanical add-ons that enable the performance of brightfield, fluorescence, spectroscopy, or phase imaging. These tools enable accurate diagnosis in outlying places. It is now available for on-site applications outside of the lab thanks to the smaller sequencing instruments. A more precise diagnosis can be made by combining many assays, including as CT imaging, lateral flow immunoassay, clinical symptoms, and viral RNA detection. Cost, time, precision, and specificity should be balanced in actual clinical circumstances, though [93].

In conclusion, a lot of work needs to be done to build rapid nanobiosensors for the detection of corona viruses or any other diseases that could cause a pandemic or endanger human lives. But NPs, like other occupations, are unquestionably advantageous and give rise to a lot of hope for future advancements because of their excellent potential for performing quick, precise, in-person early diagnosis and, more importantly, for tracking infectious diseases and averting fresh pandemic outbreaks.

Conclusion

The COVID-19 epidemic faced the challenges of globalization and time sustainability as the global viral outbreak continued to diffuse and spread. For elderly people and those with inadequate immunity, even new corona virus strain continue to offer a serious and life-threatening hazard, especially in view of the virus’s ongoing variants’ enhanced concealment, transmission speed, and immune escape proportion. In this context, the study’s nanoscale sensors truly stand out. In view of the screening and future monitoring requirements of the routine management of infectious illnesses, a highly sensitive detection strategy that is less impacted by the sampling method and sample quality must still be developed in order to identify the infected person as soon as feasible. The simultaneous identification of a large number of samples helps ease the stress on detection brought on by the epidemic's global emergence. When it comes to taking swift action in the event of an infectious disease outbreak, an early and accurate diagnosis will help. In conditions like COVID-19, when a precise solution is unavailable due to unpredictable and perplexing symptoms, early intervention can be life-saving.

Abbreviations

COVID19

Coronavirus disease 2019

WHO

World Health Organization

SARS – CoV

Severe acute respiratory syndrome COVID

MERS- CoV

Middle East respiratory syndrome COVID

ICU

Intensive care unit

CSG

Coronaviridae study group

ICTV20

International Committee on Taxonomy of Viruses

RNA

Ribonucleic acid

DNA

Deoxyribonucleic acid

AEC II

Alveolar epithelial cells sort II

PPE

Personal protective equipment’s

NPD

Nanotechnology products database

RT – PCR

Real-time reverse transcriptase-polymerase chain reaction

IgM

Immunoglobulin-M

IgG

Immunoglobulin-G

ELISA

Enzyme-linked immunosorbent assay

CLIA

Chemiluminescent immunoassay

MNP’s

Magnetic nanoparticles

PCR

Polymerase chain reaction

AuNPs

Gold nanoparticles

LSPR

Localized surface plasmon resonance

UV- Vis

Ultra violet visible

ASO’s

Antisense oligonucleotides

QDs

Quantum dots

PEDV

Porcine epidemic diarrhea virus

AuNI’s

Gold nano island

PTT

Photothermal therapy

WNF

World nano foundation

MIT

Molecular imprinting technology

NP

Nasopharyngeal

HBV

Hepatitis B virus

AgNPs

Silver nanoparticles

LOD

Limit of detection

MTB

Mycobacterium tuberculosis

HPV

Human papilloma virus

acpcPNA

aminocyclopentanecarboxylic acid Peptide Nucleic Acid

HIV

Human immunodeficiency virus

FET

Field effect transistor

ZNF

Zinc ferrite

Author Contribution

Sarita K Yadav did the conceptualization and preparation of the main manuscript; Rahul Deo Yadav did the language editing; Heena Tabassum prepared the figures; and Malti Arya did the conceptualization, grammar editing, and proofreading.

Availability of Data and Materials

Not applicable.

Declarations

Competing Interests

The authors declare no competing interests.