Advances and future directions of aptamer-functionalized nanoparticles for point-of-care diseases diagnosis

Abstract

Point-of-care (POC) diagnostics have revolutionized disease detection by enabling rapid, on-site testing without the need for centralized laboratory infrastructure. This review presents recent advances in aptamer-functionalized nanoparticles (AFNs) as promising tools for enhancing POC diagnostics, particularly in infectious diseases and cancer. Aptamers, with their high specificity, stability, and modifiability, offer significant advantages over antibodies, while nanoparticles contribute multifunctionality, including signal amplification and targeting capabilities. AFNs have demonstrated up to a 2–10 times increase in detection sensitivity and significant reductions in diagnostic timeframes. We discuss various nanoparticle types, conjugation strategies, real-world applications, and highlight innovative developments such as AI-assisted aptamer design, wearable diagnostic devices, and green nanoparticle synthesis. Challenges related to stability, manufacturing scalability, regulatory hurdles, and clinical translation are critically examined. By merging aptamer precision with nanoparticle versatility, AFNs hold transformative potential to deliver rapid, affordable, and decentralized healthcare solutions, especially in resource-limited settings. Future interdisciplinary research and sustainable practices will be pivotal in translating AFN-based diagnostics from promising prototypes to global healthcare standards.

Introduction

Prompt identification of the diseases is important in treatment, containment, and management of epidemic and pandemics [1]. Conventional diagnostic methods may involve high-tech equipment and labor complemented by skilled personnel, thus delaying the diagnosis and treatment procedure in a restrictive setting [2, 3]. Point-of-care (POC) diagnostics are medical testing procedures conducted at or near the site of patient care, enabling healthcare providers to obtain immediate, actionable results without relying on centralized laboratory facilities. POC devices, such as blood glucose meters, lateral flow assays for infectious diseases, and portable PCR systems, have revolutionized diagnostics by offering rapid results, improving patient outcomes, and reducing healthcare costs [4]. POC diagnose is crucial in infectious diseases especially in settings where there is restricted access to central laboratory [5]. By cutting down time from the moment of testing to onset of treatment, POC diagnostics might be even more crucial for the management of certain diseases. Aptamer-functionalized nanoparticles (AFNs) represent an innovative integration of two advanced technologies: aptamer-based molecular selective binding and nanoparticle-mediated multiple detection properties [6]. This synergy has produced an innovative workflow that can be applied to respond to some of the most complicated issues in diagnostics, targeted drug delivery, and treatments.

Aptamers represent small single-stranded oligonucleotides (DNA or RNA) capable of assuming powerful conformations due to intramolecular interactions to better recognize target molecules with high specificity [1, 7]. Sometimes, referred to as “chemical antibodies” for their functionality to protein antibodies, but classify differently from the last in terms of synthesis and immunogenicity [8]. Compared to antibodies, aptamers offer remarkable advantages that make them ideal candidates for POC diagnostics (Table 1). They are synthesized chemically, ensuring batch-to-batch consistency, and can be engineered for enhanced stability under a wide range of conditions. Unlike antibodies, aptamers are nonimmunogenic, exhibit superior shelf life, and can be modified easily to improve their binding affinities or integrate reporter molecules for biosensing applications [9, 10]. Aptamers can form various structures like—loops and folds, which result in flexibility of the aptamers to bind with several molecular targets. As a result of that, the functional groups of aptamers can be optimized to improve the stability, the bioavailability, or the binding capacity [11]. Moreso, they can be produced in large numbers, which does not have the batch problem other than the biologic sources of antibodies [10]. These present aptamers as valuable biorecognition elements in various diagnostic platforms diagnostics. In addition to diagnostics, aptamers have found extensive applications in the fields of targeted drug delivery [12, 13] and gene therapy [14, 15]. Their high binding specificity and ease of chemical modification make them excellent vehicles for delivering therapeutic agents, such as small molecule drugs and genetic materials like small interfering RNAs (siRNAs). siRNAs, which operate through RNA interference (RNAi) mechanisms, are powerful tools for silencing disease-associated genes and have emerged as promising therapeutic candidates for a range of conditions, including cancer and genetic disorders. By conjugating aptamers to therapeutic cargos like siRNAs, it is possible to achieve targeted and efficient delivery, minimizing off-target effects and enhancing therapeutic outcomes [12–15]. Figure 1 provides a conceptual overview of the role of aptamers as bioconjugation molecules in diagnostics, drug delivery, and gene therapy. Nanoparticles are particles of 1–100 nm range in size with properties of optical, magnetic, and chemical differences [16]. These materials can be produced with a broad range of compositions, morphologies, and surface chemistries to function in drug delivery, imaging, and diagnostic applications [17]. The conjugation of aptamers with nanoparticles thus aligns the molecular selectively of aptamers with the multifunctional characteristics of nanoparticles to form a stable structure. AFNs operate on two fundamental principles: through aptamers for control of specificity and through the versatile applications of nanoparticles. Aptamers guarantee stringent targeting of the specific molecule of interest, thus reducing interaction with other molecules and improving diagnostic or therapeutic accuracy [9]. Nanoparticles enhance aptamers through imparting more characteristics such as signal emission for imaging, targeting magnetic field for targeting, or self-lights for signal production in biosensors [8, 10]. The use of aptamers on the surface of nanoparticles also enhances the ability to diagnose a wide range of medical conditions since the nanoparticles themselves amplify the signal from aptamers, while also offering high selectivity resulting in sensitivity-based detection systems [2, 17].

Table 1.

Comparison of aptamers and antibodies in biorecognition.

Feature	Aptamers	Antibodies
Production method	Chemical synthesis (in vitro, scalable, reproducible)	Biological production (requires animals or cell cultures)
Batch-to-batch consistency	High	Variable, risk of batch differences
Modification flexibility	Easy chemical modification (e.g. labeling, conjugation)	Limited, modifications can affect binding
Stability	High thermal and chemical stability	Sensitive to temperature and pH changes
Immunogenicity	Nonimmunogenic	Can induce immune responses
Size	Small (2–3 nm)	Large (∼10–15 nm)
Cost of production	Relatively low	Higher (requires biological facilities)
Target range	Binds a wide range of molecules, including small ones	Typically limited to larger molecules (e.g. proteins)
Shelf life	Longer	Shorter, often needs refrigeration
Binding affinity	Comparable or superior	High

Figure 1.

Roles of aptamers in diagnostics, drug delivery, and gene therapy

It shows how aptamers enable enhanced diagnostics, targeted drug delivery, and siRNA-based gene therapy by leveraging their specificity, stability, and modifiability when conjugated to nanoparticles. The figure was Created in BioRender.com.

PCR, ELISA, and the cultural techniques that are commonly used in diagnostic of infectious diseases still present many challenges as highlighted by Fasogbon et al. [3] and Warhurst et al. [18]. Despite their high accuracy, conventional diagnostic methods such as PCR and ELISA are constrained by significant limitations. For instance, PCR typically requires 3–6 h for results under ideal conditions but may take up to 24–48 h when sample transportation and batching are involved [18]. Similarly, rapid diagnostic tests (RDTs) for malaria exhibit false-negative rates as high as 20%–30% in field settings. Furthermore, the high cost, ranging from $30 to $100 per molecular test, combined with the need for skilled operators and complex equipment, limits their accessibility in low-resource environments [1, 18]. These limitations point out the need for enhanced and reachable diagnostic tools and procedures. Functionalization of nanoparticles with aptamers may well be a solution to the drawbacks associated with conventional diagnostic techniques [19]. These nano biosensors have the capacity to identify a diverse number of pathogens at a very low level, which can be very useful for POC [6].

This review aims to critically examine recent advances in aptamer-functionalized nanoparticle (AFN) systems for point-of-care diagnostics. Specifically, we discuss the types of nanoparticles used, the mechanisms of aptamer conjugation, key synergistic properties, and practical case studies across different fields and provide a critical perspective on the challenges and prospects of translating AFNs into clinical and environmental POC applications.

Synergistic properties of aptamer-functionalized nanoparticles

Aptamer–nanoparticle hybrids make up sophisticated systems that take advantage of the capabilities of the aptamers and the nanoparticles and improve the efficiency of the systems when used in diagnostics and as delivery agents [6, 15, 16]. This integration fully exploits the high selectivity and affinity of aptamers used as molecular recognition units and the tunable and versatile physicochemical characteristics of nanoparticles to overcome limits on sensitivity, selectivity, and stimulus responsibility [6]. AFNs are unique chimeric systems built on the molecular selective properties of aptamers and functional versatility of nanoparticles. Such systems are critical to enhancements of diagnostics and biosensing, holding distinct features arising from the totality of their composing parts.

Aptamer properties supporting functionalization

Consequently, aptamers have features that qualify them as suitable objects for functionalization, especially with a view to biomedical uses. Their dissociation constants range from picomolar to nanomolar similar, or even superior to antibodies, suggesting that apogones are capable of sustaining relatively specific and stable interaction with many different partners, including small molecules, proteins, cells, and tissues. This versatility plays an important role diagnostically and therapeutically, where precision in targeting biomarkers is essential [16, 20].

There are, however, certain benefits of aptamers over protein-based ligands; firstly, and most importantly, aptamers are chemically modifiable [21]. The presentation of the aptamers invokes chemical modifications, such as thiols, amines, and fluorophores, in a bid to boost their stability, change their binding characteristics to liberate, or incorporation with penetrations and other substances [16]. This adaptability is one of the major aspects of their benefits in the formation of biosensors and the systems for targeted delivery of medicine. Such chemical modifications facilitate aptamers’ function at physiological conditions and therefore increase the efficacy of aptamers in clinical and diagnostic applications. Apart from chemical versatility, aptamers have large advantage in biocompatibility terms as well. Unlike protein-based ligands, aptamers are made up of nucleic acids, which, based on nature, are less prone to trigger immune responses [9]. This absence of immunogenicity is particularly desirable in therapeutic applications where immunogenicity is a big concern. In addition, due to their small size and flexible structure, they can successfully deliver diagnostic or therapeutic agents to dense biological tissues, thus targeting otherwise difficult biological compartments, such as tumor environment or intracellular biomarkers [22]. The emergence of aptamers takes the appeal even further in its development. The methods not only guarantee the synthesis of highly specific binding agents but also provides means for maintaining batch-to-batch consistency and scalability of the process. Many current remote and physical SELEX and non-SELEX procedures are in the process of optimization to develop aptamer for target ranging from small organic molecule to whole cell, thus expanding the application of aptamer in diagnostic as well as the therapeutic areas [7, 21, 23]. However, the efficient synthesis of opiate aptamers becomes another important winning point over antibodies and most other proteinaceous ligands due to the overall relatively low cost. The aptamers can be synthesized by chemical methods, which offer an advantage over biological methods in that large quantities can be produced without requiring complex cell culture systems. This scalability, coupled with their structure stability and modifiability, puts them in a good position to be used in large-scale point-of-care diagnostics, biosensors, and smart therapeutic systems [24].

Nanoparticle properties enhancing aptamer functionalization

Nanoparticles play a pivotal role as structural scaffolds and functional enhancers in the development of AFNs [20]. Their unique physicochemical properties, such as large surface area, tunable surface chemistry, and high biocompatibility, provide an ideal platform for the stable attachment and optimized presentation of aptamers. This functionalization enhances both the targeting specificity and therapeutic efficacy of AFNs [20].

Among various applications, nanoparticles have been widely employed in the construction of radioconjugates, which are biomolecules labeled with radioactive isotopes for use in diagnostics and therapy [25]. Through conjugation with aptamers, radioconjugates can be precisely directed to specific disease sites, minimizing off-target effects and significantly improving imaging sensitivity and therapeutic outcomes.

The integration of aptamers onto nanoparticle surfaces not only enhances the selectivity of radioconjugates but also improves their pharmacokinetics, tissue penetration, and stability under physiological conditions [15, 25]. This synergy has made aptamer-functionalized radioconjugates a promising platform for molecular imaging, targeted radiotherapy, and theranostic applications in modern biomedicine. These systems combine the molecular recognition properties of aptamers with the destructive or imaging capabilities of radionuclides, offering applications in cancer diagnosis, therapy, and monitoring of treatment response. Recent advances have led to the development of mitochondria-tropic radioconjugates [25], where aptamers are used to direct radionuclides specifically to mitochondria within tumor cells, amplifying the therapeutic impact while minimizing off-target toxicity. Figure 2 illustrates a typical design and application workflow of aptamer-based radioconjugates for targeted biomedical applications. Due to their large surface to volume ratio, enhanced multiple aptamers show remarkable binding interaction that upgrades the highly sensitive detection systems according to the studies by Chen et al. [24]. This is especially important in areas where high selectivity is needed, in example in the detection of cancer or pathogen presence. Nanoparticle optical characteristics, e.g. the SP of gold nanoparticles, are vital in imaging and biosensing [19]. These properties make it possible to increase the intensity of relatively weak optical signals for precise measurements of low abundance biomarkers [20]. Quantum dots, for instance, exhibit considerable fluorescence, i.e. desirable in detailed diagnostic functions. Magnetic nanoparticles improve AFNs’ applications owing to their inherent magnetic characteristics and complimentary functionalization for high selectivity and sensitive detection platforms. Consequently, due to their small size, large surface-to-volume ratio, and MR responsiveness, they are well-adapted for diagnostics in biomedical applications, including POC devices, imaging, and biomarker-based systems [26]. Also, metal oxide nanoparticles like titanium dioxide or iron oxide show catalytical and electrochemical features, thereby being important in biosensors for enhanced signal amplification and detection sensitivity as stated by Zhang et al. [27]. Particle size and shape of nanoparticles (NPs) have a significant impact on the diagnostic performance. These physical features dictate the incipient interactions with biological systems, sturdiness, surface chemistry, and signaling processes, which are critical components of diagnostic interfaces.

Figure 2.

Schematic overview of aptamer-based radioconjugates for targeted diagnostics and therapy

It illustrates the process by which aptamer-based radioconjugates target diseased cells, enabling precise delivery of radionuclides for diagnostics and therapy. The figure was Created in BioRender.com.

Types of nanoparticles used in AFNs

The choice of nanoparticles greatly influences the properties and applications of the resulting AFNs. The major categories commonly employed are:

Gold nanoparticles (AuNPs)

Gold nanoparticles are highly attractive for AFNs because of their unique surface plasmon resonance properties, which enhance signal amplification in optical biosensors. Their surfaces can be easily modified through strong thiol–gold bonds, allowing efficient and stable aptamer attachment. AuNP-based AFNs have been successfully used for colorimetric detection, photothermal therapy, and targeted drug delivery, offering exceptional sensitivity in molecular diagnostics [28].

Magnetic nanoparticles

Superparamagnetic iron oxide nanoparticles (SPIONs) are commonly used magnetic nanoparticles in AFNs. They are extensively used due to their ability to respond to external magnetic fields. Aptamer-functionalized SPIONs enable rapid target capture, separation, and magnetic resonance imaging (MRI) contrast enhancement. They have shown promise in noninvasive imaging of tumors and efficient isolation of circulating tumor cells (CTCs) from blood samples [26].

Quantum dots

Quantum dots are semiconductor nanocrystals that emit strong, tunable fluorescence upon excitation. When functionalized with aptamers, Quantum dots allow for highly sensitive and multiplexed detection of biomarkers, outperforming traditional organic dyes in stability and brightness [29]. Their nanoscale size also supports efficient cellular imaging and real-time tracking of biological processes [29].

Silica nanoparticles

Silica nanoparticles are characterized by their high surface area, porous structure, and chemical robustness. They provide abundant active sites for aptamer immobilization via silane coupling chemistry. Additionally, mesoporous silica nanoparticles (MSNs) are widely utilized as drug delivery vehicles capable of co-loading therapeutic agents alongside targeting aptamers for stimuli-responsive release in cancer therapy [30].

Liposomes and polymeric nanoparticles

Liposomes are spherical vesicles made of lipid bilayers that mimic biological membranes, offering a biocompatible and biodegradable platform for aptamer anchoring. Polymeric nanoparticles, including poly(lactic-co-glycolic acid) and chitosan nanoparticles, provide controlled release profiles and protection for sensitive payloads. Aptamer-functionalized liposomes and polymers have been engineered for targeted drug delivery, gene therapy, and vaccine development, enhancing specificity and reducing systemic toxicity [31].

Carbon-based nanomaterials

Carbon-based nanomaterials, such as graphene sheets and carbon nanotubes (CNTs), possess outstanding electrical conductivity, mechanical strength, and high surface area. Aptamer-functionalized graphene and CNTs have been widely developed for electrochemical biosensors, targeted drug delivery, and photoacoustic imaging. Their ability to facilitate electron transfer also makes them ideal for constructing high-performance diagnostic devices [32].

Aptamer–nanoparticles functionalization mechanisms

The functionalization of nanoparticles with aptamers is a pivotal step in constructing AFNs, enabling specific recognition, targeted delivery, and enhanced diagnostic performance. Functionalization strategies can be broadly classified into covalent and noncovalent methods, each offering unique advantages and challenges.

Covalent functionalization strategies

Covalent conjugation ensures strong, stable attachment of aptamers to nanoparticle surfaces through the formation of chemical bonds, enhancing durability under physiological conditions. Major covalent methods for functionalization include:

• Thiol–Gold Bonding:

  Aptamers modified with thiol (-SH) groups form strong Au–S bonds with gold nanoparticles (AuNPs), enabling high-density and oriented immobilization ideal for biosensing and drug delivery systems [16]. Khorshid et al. [33] described an aptamer functionalized gold nanoparticles of dasatinib for targeting HER-2 in breast cancer cells.

• Amine–Carboxyl Coupling (EDC/NHS Chemistry):

  Carboxyl groups on nanoparticle surfaces react with primary amines on aptamers using EDC/NHS activation to form stable amide bonds. This technique is common for silica nanoparticles and polymeric carriers [19].

• Maleimide–Thiol Coupling:

  Maleimide-functionalized nanoparticles react with thiolated aptamers via Michael addition, offering site-specific conjugation with high efficiency. This method is widely used for precision therapeutic delivery [34]. Tang et al. [34] used Maleimide-functionalized liposomes in doxorubicin conjugation for breast cancer therapeutics yielding prolonged retention and enhanced efficacy.

Noncovalent functionalization strategies

Noncovalent methods rely on physical interactions without forming direct chemical bonds, preserving the aptamer’s native structure but generally resulting in less stable conjugates. The key noncovalent interactions for the functionalization include:

• Electrostatic Interactions:

  Electrostatic attraction between negatively charged aptamers (phosphate backbone) and positively charged nanoparticles (e.g. chitosan-coated nanoparticles) allows for simple and reversible functionalization [35]. Electrostatic attractions were described in chitosan-coated fluoro-functionalized covalent organic framework used as adsorbent for efficient removal of per-and polyfluoroalkyl substances from water [36].

• Hydrophobic Interactions:

  Aptamers can adsorb onto hydrophobic nanoparticle surfaces such as polymeric micelles or lipid-based carriers, beneficial in drug delivery formulations where mild conditions are required. Zhao et al. [37] described the application of aptamer-functionalized magnetic hydrophobic polymer with synergetic effect for enhanced adsorption of alternariol from wheat.

• π–π Stacking and Intercalation:

  In systems like doxorubicin-loaded aptamer conjugates, π–π stacking enables noncovalent embedding of therapeutic molecules between aromatic bases of aptamers, facilitating controlled release applications [38]. Aptamers loaded with doxorubicin via π–π stacking have been employed for targeted chemotherapy, improving drug accumulation in tumors while minimizing systemic toxicity [39].

Table 2 presents the comparison of covalent and noncovalent functionalization strategies. While covalent functionalization provides superior stability and long-term reliability, it may require complex chemistry and risk aptamer degradation. In contrast, noncovalent approaches preserve aptamer functionality but may limit application scope due to weaker interactions.

Table 2.

Critical comparison of covalent vs. noncovalent strategies.

Feature	Covalent functionalization	Noncovalent functionalization
Bond strength	Strong, stable chemical bonds	Weak, reversible physical interactions
Aptamer structure	Possible alteration	Structure preserved
Stability	High under physiological conditions	Lower, prone to desorption
Ease of preparation	Requires chemical reagents and activation steps	Simpler and faster
Applications	Long-term in vivo use, implantable devices	Rapid prototyping, disposable sensors

Practical case studies of AFNs

Some practical case studies of AFNs are summarized in Table 3 and discussed below.

Table 3.

Summary table of key information across some AFN case studies.

Application area	Nanoparticle type	Aptamer target	Conjugation method	Key metric	Real-world application
Cancer diagnosis	Gold NP	PSA	Thiol-Gold Bonding	LOD 1 pg/mL	Point-of-care biosensor prototypes (clinical evaluation)
Cancer therapy	Liposome	Nucleolin (AS1411 aptamer)	Lipid insertion (noncovalent)	2.5× tumor accumulation	Triple-negative breast cancer preclinical models
Infectious disease detection	SPIONs + AuNPs (LFA strip)	Mammaliicoccus sp., Pseudomonas sp.	Amine-Carboxyl Coupling + Lateral Flow Assay	LOD 1.5 × 10³–104 CFU/mL	ICU infection detection kits
Environmental monitoring	Gold NP	Mercury ion (Hg²+)	Thiol-Gold Bonding	LOD 0.20 nM (lower than EPA limit)	Water quality monitoring
Drug delivery and controlled release	PEG-PLGA NP	Tumor biomarkers (various)	Maleimide-Thiol Coupling + PEGylation	Enhanced bioavailability, improved tumor penetration	Oncology drug delivery systems

Cancer diagnosis and therapy

Gold nanoparticles (AuNPs) functionalized with prostate-specific antigen (PSA)-targeting DNA aptamers have been developed for sensitive cancer biomarker detection [40]. Utilizing the strong thiol–gold covalent bonding method, the aptamers are robustly attached to the AuNP surface, facilitating the creation of a highly specific biosensor. The developed sensor has an extended linear range of 1–100 ng/mL and a very low limit of detection down to 1 pg/mL, demonstrating outstanding specificity against nontarget serum proteins. Prototype diagnostic kits integrating this platform have been developed for point-of-care use and are currently undergoing clinical evaluation, representing a promising advancement in early prostate cancer detection [41].

In cancer therapy, aptamer-functionalized liposomal systems have shown significant promise for targeted drug delivery. Specifically, liposomes were engineered with the AS1411 DNA aptamer, which selectively binds to nucleolin, a protein overexpressed on cancer cells [42]. Using noncovalent insertion of the aptamer into the liposome membrane, the delivery system achieved ∼2.5-fold greater drug accumulation in tumors compared to nontargeted liposomes. Preclinical studies, particularly in triple-negative breast cancer models, have demonstrated enhanced therapeutic efficacy and reduced systemic toxicity, setting the stage for potential clinical translation [43].

Infectious disease detection

For infectious disease applications, magnetic nanoparticle (SPION)-based platforms have been functionalized with Staphylococcus aureus-specific aptamers using covalent amine-carboxyl conjugation via EDC/NHS chemistry [44]. A portable biosensor that combines conjugated AuNPs with an aptamer-based lateral flow assay (LFA) platform for the real-time analysis of Mammaliicoccus sp. and Pseudomonas sp. This assay was based on the sandwich-type format using a bacteria-specific primary aptamer (Apt1) conjugated with 23 nm ± 1.27 nm AuNPs as a signal probe and another bacteria-specific secondary aptamer (Apt2)-coated nitrocellulose membrane as a capture probe. The visual limit of detection of the strip for Mammaliicoccus sp. and Pseudomonas sp. was 1.5 × 10⁴ CFU/mL and 1.5 × 10³ CFU/mL, respectively [44].

Environmental monitoring

In environmental sensing, carbon nanotube-based aptamer systems have been deployed for mercury ion (Hg²⁺) detection in water supplies [45]. Using thiol-gold bond, Hg²⁺-specific DNA aptamers are covalently adsorbed onto the surface of gold nanoparticles. A linear relationship between color change time and Hg²⁺ concentration was obtained in the 10–600 nM range with a detection limit of 0.20 nM, which is much lower than the limit value (10 nM) defined by the US Environmental Protection Agency for Hg²⁺ in drinking water. AuNPs are known to exhibit strong surface plasmon resonance (SPR) absorption from visible to near-infrared region, resulting in a color change, making them commonly used as colorimetric probes in the sensing field [45].

Drug delivery and controlled release systems

Aptamer-functionalized nanocarriers offer distinct advantages that effectively address the major limitations of conventional systemic anticancer therapies. By conjugating aptamers to nanoparticles, these systems enable actively controlled, site-specific delivery of therapeutic agents to tumor tissues, thereby enhancing treatment precision and minimizing off-target effects [46]. Among the various nanocarrier platforms, amphiphilic block copolymers such as polyethylene glycol–poly(lactic-co-glycolic acid) (PEG-PLGA) have emerged as particularly promising. These copolymers self-assemble into multifunctional nanoparticles capable of prolonged systemic circulation and improved bioavailability. Furthermore, they possess the versatility to encapsulate a wide range of therapeutic agents, including small molecule drugs, gene-targeting therapeutics, traditional Chinese medicine (TCM) compounds, and multitarget enzyme inhibitors, thereby expanding their clinical applicability in oncology [47].

To enhance tumor specificity, the surface of PEG-PLGA nanoparticles is often further functionalized with targeting ligands such as aptamers. This surface modification facilitates active targeting mechanisms, promoting selective accumulation of the nanocarriers within tumor tissues via molecular recognition of overexpressed biomarkers. Consequently, these aptamer-functionalized PEG-PLGA systems demonstrate improved tumor penetration, increased therapeutic efficacy, and reduced systemic toxicity compared to conventional delivery methods [47]. Overall, these innovative nanocarrier platforms represent a significant advancement in the field of targeted drug delivery and personalized cancer therapy.

Limitations of aptamer-functionalized nanoparticles-based diagnostics

Despite the many advantages, aptamer-functionalized nanomaterial complexes are not common in use now. However, there is a challenge in functionalizing and synthesizing of the resulting nanoparticles, which may take time and can be complex [17]. Despite the high sensitivity of the technology and its ability to detect biomolecules by using AFNS, under various environment, it is possible that aptamer-functionalized nanoparticles have the limitation of instability of aptamers in biological fluids [17], the challenges of nonspecific binding due to the negative charge of long aptamers, and the problem of high background signals in complex samples. Issues such as enzymatic degradation, complex sample matrix interference, and manufacturing scalability are also of concerns [48]. Strategies to overcome these challenges, including chemical modifications like PEGylation to enhance nuclease resistance and the development of hybrid aptamer systems to reduce nonspecific binding, have also been discussed. Thus, while the aptamer–nanoparticle relationships achieved an impressive level of specificity, this method is still constrained by high background and absorption [49]. The efficiency or the effectiveness of the complex may also be constrained by challenging dosimetry, which may lead to an inaccurate delivery of an inefficient complex to the target organ or cells [14]. Moreover, natural nucleic acid is sensitive to nuclease and may therefore affect the effectiveness of in vivo applications of advanced diagnostic complexes. Further, the chemical modification of the unmodified aptamers might affect the aptamer complexes for their targeting abilities and recognition affinity toward the molecules of interest [14, 19]. The identification of disease-related molecules in other body fluids such as blood could sometimes be tricky more so when these molecules are present in low quantities in the body fluids. For instance, the identification of circulating tumor cells and their concentration is negligible in blood, which can be unmanageable for the conjugate [50]. Moreover, because of the high cost and complexity of manufacturing of such modern diagnostic devices, as well as the need for qualified professionals in the creation of diagnostic equipment, the availability of such diagnostic equipment will be extremely problematic in regions and countries with low economic development [1–3, 26]. Such environmental and chemical changes could prevent the aptamer from binding to any nanoparticles used in diagnostic systems in living things. Apart from this, long aptamers with negative charges could hinder the aptamer and nanoparticles from adhering to each other, which may result in many nonspecific binding [14].

Environmental impact of nanoparticles and the concept of green chemistry

The synthesis, use, and release of nanoparticles pose effects to the environment because it is stable, mobile, bioaccumulate, and toxic in the context of ecosystems [51]. In many cases, the nanoparticles synthesis including gold nanoparticles is carried out using highly toxic reducing agents including sodium borohydride, which releases toxic by-products [52]. Discharging these by-products haphazardly poses a serious risk to water and soil, specifically, endangering the water bodies and the land [51, 52]. Research has also indicated that nonbiodegradable nanoparticles, S&P of Silver and titanium dioxide, respectively, concentrated in the aquatic life systems upsetting the microbic balance and biomagnifying various toxic stress responses in organisms [53].

Efforts to mitigate these impacts have led to the development of green synthesis methods that use biological agents such as plant extracts and microorganisms as reducing agents. Azadirachta indica (neem) leaf extract for gold nanoparticles and microbial-mediated nanoparticle synthesis using Fusarium oxysporum [54, 55]. These eco-friendly approaches eliminate the need for toxic chemicals and reduce the energy required for nanoparticle production and significantly reduced the environmental hazards associated with conventional methods [56]. The sustainable preparation of gold nanoparticles (AuNPs) using green chemistry approaches is a growing area of research, driven by the need to minimize environmental impact while ensuring biocompatibility for biomedical applications. Traditional synthesis methods often rely on toxic reducing agents, such as sodium borohydride or hydrazine, and stabilizing chemicals, which generate hazardous byproducts. Green chemistry approaches replace these harmful reagents with eco-friendly alternatives, leveraging plant extracts, microorganisms, or biomolecules as reducing and stabilizing agents [56].

In addition to green synthesis, recycling and reuse of nanoparticles from biomedical and industrial waste are gaining traction as sustainable practices to minimize their environmental footprint, although green synthesis is still being challenged with difficulty in controlling nanoparticle size, reproducibility issues, and scalability concerns [57]. Regulatory measures are also being implemented to enforce stricter nanoparticle disposal protocols and promote lifecycle assessments [58]. Moreso, there is a current move toward lifecycle assessments (LCAs) and stricter disposal protocols enforced by environmental agencies to mitigate nanoparticle waste accumulation in ecosystems [59]. These steps are critical for ensuring that the widespread adoption of nanoparticle-based technologies does not come at the expense of ecological health [51].

Future perspectives

The prospect of aptamer-functionalized nanoparticles is the exploration of other innovative technologies and materials to improve the existing challenges. Relative to aptamer design, there are promising accounts of using artificial intelligence and machine learning to study large dataset to find sequences with higher specificity and stability. By considering this computational approach to SELEX, time and costs are drastically cut down. Recent advances in artificial intelligence (AI) and machine learning (ML) are increasingly shaping the future of aptamer design. These technologies offer the ability to predict aptamer-target interactions, optimize aptamer sequences for higher specificity and stability, and significantly reduce the time and cost of experimental selection processes. Tools such as deep learning frameworks and molecular docking simulations are already being used to identify high-affinity aptamers more efficiently. Future integration of AI-driven approaches with aptamer-functionalized nanomaterials (AFNs) could enable rapid, personalized diagnostic platforms and therapeutic solutions, especially in rapidly evolving fields like oncology and infectious disease management [21].

More opportunities are presented with such forms of hybrid nanomaterials as MOFs and graphene for enhancing AFN performance. MOFs bring modularity that translates into experience control together with high surface areas, which makes them essential in drug delivery and the diagnosis process. It is the same with graphene composites enhancing conductivity and mechanical properties to be used in developing biosensors [60]. These materials are supposed to solve some problems like nonspecific binding and degradation of a product under the physiological conditions. The incorporation of AFNs into wearable technology and portable POC systems has a strong potential to revolutionize biomarker sensing, as well as personalized medicine. The 3D printing technology and microfluidics are offering an opportunity to design and fund cheap and effective biosensors for widespread use in limited-resource setting. Due to such progressive changes, healthcare facility availability around the world is expected to improve by offering swift, precise diagnostics to people incapable of affording healthcare solutions [61]. Fighting the global health challenges calls for further investment in the devices based on the AFN. If these devices come equipped with multiplexed detection and the ability to connect to smartphones, they could revolutionize surveillance and handling of diseases global [20, 61].

Beyond current laboratory developments, integrating wearable technologies and microfluidic systems with AFN-based diagnostics offers exciting avenues for future clinical applications, though several critical challenges must be addressed to ensure successful translation. Wearable technology and microfluidics represent transformative opportunities for AFN-based diagnostics. Integrated wearable sensors can enable continuous, noninvasive monitoring of disease biomarkers, offer real-time health insights and facilitate early intervention [62]. Microfluidic platforms allow precise sample handling and miniaturized analysis, enhancing portability and reducing assay times, thus making AFN-based devices highly suitable for point-of-care applications. However, translating AFN research into clinical use faces several challenges, including ensuring the stability and reproducibility of AFNs across diverse biological environments, meeting stringent regulatory standards, achieving scalable and cost-effective manufacturing, and validating clinical performance in large, diverse patient populations. Overcoming these barriers will be essential to fully realize the promise of AFNs in revolutionizing personalized and decentralized healthcare.

Conclusion

Aptamer-functionalized nanoparticles (AFNs) have emerged as powerful tools in advancing point-of-care diagnostics due to their exceptional specificity, tunable chemistry, and potential for rapid, low-cost detection. By combining the molecular recognition capabilities of aptamers with the multifunctionality of nanoparticles, AFNs significantly enhance diagnostic sensitivity, selectivity, and portability. However, challenges remain, including the stability of aptamers in physiological environments, manufacturing scalability, and the need for robust regulatory frameworks to ensure clinical translation.

Future research should focus on overcoming these limitations through chemical modifications to improve aptamer stability, standardized scalable production techniques, and comprehensive clinical validation. Integration with emerging technologies, such as wearable devices for real-time monitoring, microfluidic platforms for sample miniaturization, and AI-driven aptamer design, holds immense promise for expanding the accessibility and performance of AFN-based diagnostics. If these advancements are realized, AFNs have the potential to transform healthcare by enabling decentralized, personalized, and early disease detection, ultimately improving health outcomes globally, especially in resource-limited settings.

Author contributions

Ilemobayo Victor Fasogbon (Conceptualization, Methodology, Writing—original draft), Erick Nyakundi Ondari (Supervision, Validation, Writing—review and editing), Deusdedit Tusubira (Supervision, Validation, Writing—review and editing), Tonny Kabuuka (Investigation, Validation, Visualization, Writing—review and editing), Ibrahim Babangida Abubakar (Investigation, Validation, Visualization, Writing—review and editing), Wusa Makena (Data curation, Formal analysis, Writing—original draft), Angela Mumbua Musyoka (Data curation, Formal analysis, Writing—original draft), Patrick Maduabuchi Aja (Project administration, Supervision, Writing—review and editing).

Conflict of interest statement. The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper. The authors declare no financial interests/personal relationships which may be considered as potential competing interests.

Funding

This research did not receive any specific grant from funding agencies in the public, commercial, or not-for-profit sectors.

Data availability statement

No new data were generated or analysed in support of this research.

Declaration of generative AI and AI-assisted technologies in the writing process

During the preparation of this work, Ilemobayo Victor Fasogbon used Scholar GPT to improve the readability and language of the manuscript. After using this tool, he reviewed and edited the content as needed and takes full responsibility for the content of the published article.