Nanoparticle-based approaches for bacterial detection and therapy

Abstract

Abstract

The advent of nanotechnology has revolutionised approaches to identifying and combating bacterial infections. This review highlights the latest applications of nanoparticles (NPs) for bacterial detection and treatment, with a focus on their translational potential in clinical settings. We discuss advanced nanotechnology-enabled biosensing platforms that offer ultra-sensitive, rapid and precise diagnostics capabilities crucial for addressing antibiotic-resistant pathogens. In addition to detection, various nanoparticles demonstrate multiple antibacterial mechanisms and function as targeted drug-delivery vehicles. The review also examines current clinical trials involving nanoparticle-based therapeutics, underscoring their promise for overcoming antimicrobial resistance.

Key points

• Nanoparticles enable rapid and sensitive detection of bacterial infections.

• Multiple antibacterial mechanisms improve efficacy against resistant pathogens.

• Translational challenges must be addressed for successful clinical application.

Introduction

According to the 2019 World Health Organisation (WHO) report, six of the ten major global health concerns were related to infectious diseases, including HIV (Human immunodeficiency viruses), dengue, Ebola, antibiotic resistance and pandemic influenza. Bacterial infections were identified as the second leading cause of mortality worldwide. In the same year, antimicrobial resistance (AMR) was estimated to directly cause 1.27 million deaths (95% CI 0.911–1.71) and indirectly contribute to approximately 4.95 million deaths (95% CI 3.62–6.57) globally. Lower respiratory infections alone accounted for over 1.5 million deaths associated with resistance, making them the most severe and costly infectious condition worldwide (Zhang et al. 2023).

The growing gap between bacterial resistance and new antibiotic development has made bacterial infections a critical healthcare challenge (Bush et al. 2011). To address this, innovative antibacterial treatments are urgently needed. Nanotechnology has shown promise over recent decades, offering unique mechanisms to combat resistance (Abdollahi et al. 2024; Wathoni et al. 2024). Nanoparticles (NPs) can interact with bacterial membranes, inducing oxidative stress, disrupting efflux pumps and compromising membrane integrity (Alav et al. 2018; Reza et al. 2019). Unlike traditional antibiotics, NPs can penetrate biological and biofilm barriers (Bolenwar et al. 2023). They also inhibit bacterial growth by blocking quorum sensing, which drives virulence, resistance and proliferation. However, some bacteria exhibit innate or acquired resistance to NPs after prolonged exposure (Li & Xu 2024). Therefore, precise NP-based therapies are needed to achieve maximum antibacterial efficacy at minimal concentrations.

Nanotechnology has greatly advanced the fight against bacterial infections by enabling sensory nanoparticles to detect illnesses at very early stages (Shen et al. 2021; Wang et al. 2022). Detecting and distinguishing pathogens at low concentrations is vital for selecting appropriate antibiotics and preventing adverse effects (Yu et al. 2024a, b). Even a small number of bacteria can cause serious health problems, making highly sensitive detection methods essential.

This review comprehensively discusses metallic, metal-oxide, polymeric, lipidic and carbon-based nanoparticles, emphasising their diagnostic capabilities, antibacterial mechanisms and translational potential.

Additionally, the review focuses on the use of nanoparticles (NPs) for bacterial detection and their antibacterial mechanisms. It also examines bacterial genetic and population-level responses to nanotechnology-based strategies, along with potential health and environmental challenges (Corsi et al. 2023).

Recent reviews emphasise that effective nanoparticle-based antibacterial strategies must integrate mechanistic efficacy with translational considerations such as safety, scalability and regulatory feasibility (Khalifa et al. 2025; Tang et al. 2025). In particular, comprehensive analyses highlight that clinically relevant nanomaterials should bridge laboratory-scale antibacterial performance with real-world implementation to address antimicrobial resistance effectively (Savadi et al. 2025).

Nanotechnology-based bacterial detection

Rapid, selective and sensitive detection of pathogens in food, water and air samples is essential to prevent outbreaks, guide treatment and ensure environmental safety. Traditional diagnostic methods—such as phenotypic analysis, ELISA (enzyme-linked immunosorbent assay), genetic testing, biochemical labelling and bacterial culture are labour-intensive, require extensive pre-treatment, enrichment steps, advanced equipment and skilled personnel (Khan et al. 2024).

To overcome these limitations, innovative sensors have been developed to detect microorganisms at very low concentrations within seconds to hours. These systems use aptamers, antibodies, enzymes, DNA or bacteriophages as recognition elements (Lin et al. 2023).

For example, surface plasmon resonance (SPR)-based plasmonic nanoparticles like gold and silver NPs are widely used (Karthikeyan & Rathinasabapathi 2024; Schmitz et al. 2023). When conjugated with aptamers, phages or antibodies, they specifically bind target bacteria, causing aggregation or plasmon peak shifts, which produce measurable colour changes. Techniques such as spectroscopy, electrochemical sensing and optical imaging further track these interactions with high precision (Qi et al. 2022).

Additionally, unlabelled array-based sensors function like artificial noses, detecting bacteria through unique optical or electrical fingerprints. Ultrahigh-frequency optomechanical resonators can also identify microorganisms by measuring their vibrational modes (Gil-Santos et al. 2020).

Figure 1 illustrates recent advances in nanotechnology based bacterial detection methods.

Fig. 1.

Nanoparticle based bacterial detection strategies, approaches included immune-based sensors (antibody-nanoparticle conjugates with colourimetric or SPR signals), aptasensors aptamer-nanoparticle recognition), phage-based sensors, nanoarray based detection and electronic nose (VOC sensing) platforms

Immune-based sensors

Engineered nanomaterials are increasingly used in biomedical applications, with gold nanoparticles (AuNPs) being especially popular due to their unique optical, electrical and physicochemical properties, ease of synthesis, tunable size and shape and low toxicity. AuNPs are widely applied in sensing and imaging, including colourimetric assays, LSPR (localised surface plasmon resonance)–based assays, electrochemical sensors, FRET (fluorescence resonance energy transfer), quartz crystal microbalance and SERS (surface-enhanced Raman spectroscopy).

In sensing, ligand–receptor interactions with AuNPs alter surface plasmon resonance (SPR) or colourimetric responses, often visible as aggregation of target pathogens. SPR results from electron cloud oscillations in metallic nanoparticles, making binding events directly measurable. For example, AuNPs conjugated with antibodies can aggregate upon binding to bacteria, producing a detectable purple colour shift (Oliveira et al. 2023; You et al. 2020). Further sensitivity improvements are achieved by increasing nanoparticle surface area. Like biotinylated gold nanoparticles, for instance, produced stronger signals and a lower detection limit (1 × 10⁻¹¹ M) than free antibodies, showing the importance of particle size and surface properties (Lyu et al. 2021; Sarratea et al. 2021).

Magnetic nanoparticles (MNPs) have been incorporated into SPR immunosensors for rapid Salmonella Typhimurium detection. Using two monoclonal antibodies—one conjugated to MNPs and the other immobilised on the sensor surface—the assay showed a 7.5- to 14-fold signal increase, with detection limits of 5.2 log CFU/g in lettuce and 4.7 log CFU/mL in buffer (Bhandari et al. 2022). LSPR-based AuNP biosensors have also been developed to detect E. coli strains producing Shiga-like toxins, with colour intensity shifts indicating bacterial presence (Yaghoubi et al. 2023; Yang et al. 2022).

Colourimetric immunosensors are also used to detect bacteriophages. For example, AuNPs functionalised with anti-T7 antibodies specifically captured the T7 phage, causing a visible red-to-purple shift, whilst controls with M13 phage showed no change, demonstrating high specificity (Lesniewski et al. 2014).

The type of antibody determines target specificity. A notable example is the nano-fluorescent sandwich immunoassay (nano-FSIA), which uses streptavidin–biotin chemistry in 96-well plates to enhance antibody immobilisation. Coupled with nanoparticles, this approach improved sensitivity and reduced cost due to the strong fluorescence signal and biocompatibility of the probes (Balaji Viswanath et al. 2018).

Further innovations include electrochemical biosensors for E. coli O157:H7. One study used CdS quantum dots within a ZIF-8 core–shell structure (CdS@ZIF-8) conjugated to anti-E. coli antibodies. After surface modification, the system released Cd²⁺ ions upon HCl treatment, quantified by differential pulse voltammetry, achieving a detection limit of just 3 CFU/mL, 16 times more sensitive than conventional methods (Zhong et al. 2019). Similarly, a conductometric biosensor with a PANI/ZnO nanocomposite and immobilised antibodies demonstrated high specificity and sensitivity (Chen et al. 2023).

AuNPs dominate biomedical sensing due to their tunable morphology and strong optical and electrical properties. Magnetic nanoparticles extend these methods for rapid Salmonella and Shiga toxin-producing E. coli detection. Bacteriophage-targeting immunosensors also offer high sensitivity and species-level specificity, making them valuable tools for rapid pathogen identification.

Aptasensors

Monoclonal antibodies are highly sensitive and selective for bacterial detection but are expensive, time-consuming to produce and often face issues with solubility and stability. Aptamers offer a promising alternative. These short single-stranded DNA, RNA or peptide sequences (20–60 nucleotides) fold into specific three-dimensional structures, allowing them to bind targets such as bacteria, proteins and enzymes with high affinity and specificity. The term aptamer derives from Latin: aptus (“fit” or “adapt”) and meros (“part” or “unit”) (Domsicova et al. 2024).

In the 1990 s, Ellington and Gold introduced the Systematic Evolution of Ligands by Exponential Enrichment (SELEX) method for aptamer screening. Unlike antibodies, aptamers are easier to synthesise, cost-effective and stable under diverse conditions (Zhou et al. 2024).

Wulff-type boronic acid–functionalised magnetic nanoparticles (MNPs@B–N/APBA) were combined with E. coli O157:H7-specific antibodies to form sandwich complexes with red fluorescent carbon dots (R-CDs). Upon release, the R-CDs amplified fluorescence signals, enabling highly sensitive quantitative detection of E. coli O157:H7. Similarly, using an external magnetic field, E. coli cells were isolated, sorted and concentrated within just two hours—much faster than conventional methods. This approach can be adapted to detect various bacteria using epitope-specific aptamers (Ling et al. 2024).

Building on aptamers’ specificity, a dual aptamer plasmonic-colourimetric detection platform was developed using catalase to hydrolyse H₂O₂ and etch silver nanoplates. This allowed simultaneous LSPR peak shifts and visible colour changes, enabling naked-eye detection of Staphylococcus aureus at levels as low as 60 CFU/mL (Zhan et al. 2022).

A toggle-cell SELEX approach identified two high-affinity ssDNA aptamers (Kd in the nanomolar range) targeting Bacillus subtilis, validated in diverse soil samples and field trials (Manfredini et al. 2023). Similarly, SA61 aptamers, conjugated to 13-nm gold nanoparticles (GNPs), enabled rapid S. aureus detection. After 30 min of incubation and centrifugation, a distinct red pellet formed, indicating a detection limit of 7.5 × 10⁶ cells/mL, even in mixed bacterial samples (Lim et al. 2021). Another aptamer pair, SA37 and SA81, showed strong simultaneous binding to S. aureus with high specificity, confirmed using colourimetric assays and fluorescence imaging (Nguyen et al. 2022).

Additionally, graphene oxide–gold nanostar (GO-Au NS) composites were developed as SERS tags. This captured E. coli and S. aureus simultaneously, producing a strong electromagnetic field enhancement and achieving an exceptionally low detection limit of 10 CFU/mL (Zhao et al. 2023). This demonstrated the potential of aptamer-nanoparticle hybrids for ultrasensitive pathogen detection.

Aptamers provide a cost-effective, stable and highly specific alternative to antibodies for bacterial detection. Techniques such as SELEX allow for rapid identification of target-specific aptamers. Examples include Wulff-type boronic acid MNPs for E. coli, dual aptamer-silver nanoplate systems for S. aureus, and GO-Au NS composites for simultaneous detection of multiple bacteria. These advances highlight aptamer-based nanosensors as powerful tools for rapid, sensitive and selective diagnostic applications.

Bacteriophage-based sensors

Whilst aptamers are widely used in research, diagnostic aptasensors face limitations such as low stability, short half-life in biological media, secondary structure formation in larger nucleic acids and cross-reactivity with non-target analytes (Lakhin et al. 2013).

Bacteriophages offer a highly specific alternative as they can recognise both live and dead bacterial cells and replicate within live cells whilst expressing proteins that bind to bacterial receptors (Bisesi et al. 2024). They are inexpensive, easy to produce and more stable than antibodies, which degrade under extreme pH or temperature (Ranveer et al. 2024). Through genetic engineering, phages can be customised to create unique receptor-binding proteins (RBPs) to target specific bacterial species. For instance, M13 phages have been engineered as scaffolds to express RBPs, enabling detection of specific bacteria using chimeric phages (Wang et al. 2024).

One example is a one-step, label-free colourimetric method for detecting Vibrio parahaemolyticus. M13 phages were conjugated with nanobodies (Nb) from camelid heavy-chain antibodies and modified through thiolation on pVIII shell proteins (Wang et al. 2023).

Without target bacteria: AuNPs aggregate, causing a visible colour change due to surface plasmon resonance (SPR). With target bacteria, nanobody-bacteria binding prevents AuNP aggregation, keeping the original colour intact. This simple assay showed high sensitivity and specificity with a visual detection limit of 10⁴ CFU/mL and a quantitative limit of 10³ CFU/mL within 100 min.

Fluorescence localisation, pull-down assays and molecular docking were used to identify two-phase displayed peptides (PDPs) that specifically bind to Staphylococcus aureus outer membrane proteins. This led to the development of a double-PDP colourimetric biosensor, where bacterial presence inhibited AuNP aggregation, resulting in a visible colour shift. This approach achieved a detection limit of 2.35 CFU/mL with a wide dynamic range (10²–10⁸ CFU/mL) (Hussain et al. 2021). Phages are also being explored for nanotechnology-based drug delivery. Custom nanocarriers built from phages can deliver therapeutic agents or diagnostic molecules with high precision. Phage ligand display systems are now emerging as versatile platforms for targeted delivery and detection (Stachurska et al. 2022).

A cost-effective strategy involves immobilising phages on nanoparticles. For example, a silica-binding protein (L2) was inserted into the T7 phage capsid to enable attachment to silica-coated magnetic nanoparticles. Adding a flexible linker significantly increased immobilisation density compared to wild-type phages, reducing costs whilst enhancing specificity (Hufziger et al. 2022). Similarly, genetically modified phages producing monomeric streptavidin were combined with magnetic nanoparticles coated in biotin to detect E. coli at levels below 10 CFU in 100 mL of water (Carmody & Nugen 2023).

Additionally, tail spikes from phages such as Salmonella P22, Bordetella BPP-1 and E. coli have been integrated into biosensors because of their ability to enzymatically degrade bacterial cell walls, further enhancing detection efficiency.

Phage-nanoparticle hybrids combine the specificity of bacteriophages with the versatility of nanoparticles, offering a powerful, cost-effective platform for pathogen detection and drug delivery. These systems hold strong potential for rapid diagnostics and precision antibacterial.

Array-based sensors

Biorecognition components enhance sensor sensitivity and selectivity but often face challenges such as instability, potential toxicity and the need for complex design and manufacturing to ensure reliable performance. To overcome these limitations, array-based sensing has been developed to detect and differentiate microorganisms without recognition elements or molecular labels (Bian et al. 2024). When exposed to plasmonic nanoparticles (NPs) of varying sizes, compositions and surface chemistries, bacteria or analytes generate distinct optical responses such as changes in light scattering, fluorescence emission or UV absorbance (Askim et al. 2013; Wang et al. 2022).

Nitrocellulose (NC) membranes, which are porous and hydrophilic, effectively filter small contaminants and promote the growth of target microorganisms. In situ growth of plasmonic gold (Au) nanocrystals on bacteria enhances stability and sensitivity, enabling efficient staining and precise quantitative analysis. These in situ synthesised nanocrystals are more stable than pre-synthesised ones, ensuring consistent performance. Plasmonic processes further amplify bacterial signals, with Au nanocrystals serving as both visual probes and signal enhancers (Askim et al. 2013).

A dual fluorescence “turn-on” supramolecular sensor array, composed of three complexes (C1–C3), three positively charged fluorophores (A1–A3), and cucurbit[7]uril, was able to identify 10 bacterial species within 30 s. It also quantitatively detected common strains, differentiated mixed populations and accurately analysed urine samples containing various bacteria (Wang et al. 2022). This system is simple, rapid stable and resistant to interference, making it well suited for clinical applications.

By using a few sensor elements with multiple signal outputs, this approach reduces time and cost whilst maintaining high diagnostic capability. Array-based sensing thus bridges the gap between laboratory research and real-world diagnostics, improving pathogen detection and medical decision-making.

Optoelectronic nose

Optoelectronic noses (e-noses) are advanced diagnostic platforms that mimic the human olfactory system to detect volatile organic compounds (VOCs) released by bacteria. VOCs act as chemical fingerprints, enabling the identification of bacterial species and monitoring of their growth and activity. By combining sensor arrays with pattern recognition algorithms, e-noses can provide species-specific bacterial identification and early infection detection. To improve sensitivity and selectivity, modern e-noses integrate nanomaterials as sensing elements (Bian et al. 2024).

• Metal oxide nanoparticles (e.g. ZnO, TiO₂, SnO₂) enhance gas adsorption and signal transduction.

• Gold nanoparticles (AuNPs) improve optical readouts.

• Carbon-based nanomaterials, such as carbon nanotubes and graphene, increase surface area and provide tunable conductivity.

These components allow e-noses to accurately distinguish bacterial “breath prints,” making them powerful, non-invasive diagnostic tools for rapid bacterial detection (de Jesús Beleño-Sáenz et al. 2021).

Example applications

Researchers developed a portable e-nose device with ten organically functionalised AuNP-based gas sensors. It successfully detected Mycobacterium bovis in faecal samples from wild pigs. By using brief voltage pulses, the device improved signal stability and detection accuracy (de Jesús Beleño-Sáenz et al. 2021). Another innovative system used interdigitated electrodes (IDEs) coated with carbon dots (C-dots) of varying polarity. When exposed to different vapours, these electrodes exhibited rapid capacitance changes caused by the replacement of adsorbed water molecules with gas molecules, altering polarity and dielectric constant. This platform is durable, reusable, cost-effective and easy to assemble, making it ideal for bacterial VOC analysis (Volatile Organic Compound test) (Bian et al. 2024).

Additionally, colourimetric sensor arrays (CSAs) have emerged as simple and portable e-nose alternatives. Unlike traditional systems, CSAs provide a visual readout, using colour-changing reagents like metalloporphyrins and chemoresponsive dyes to indicate bacterial presence (Bordbar et al. 2020; de Jesús Beleño-Sáenz et al. 2021).

Despite advances in tuberculosis (TB) diagnostics, there is still no rapid, low-cost point-of-care (POC) test for widespread use. Nanotechnology-based approaches show great promise in addressing this gap. One such method, nanodisk–mass spectrometry (Nano-Disk-MS), uses gold and silica nanoparticles to enhance MALDI-TOF MS signals, enabling highly sensitive and specific detection of Mycobacterium tuberculosis (MTB) antigen peptides (Chakraborty et al. 2024; Mendes et al. 2022).

Additionally, functionalised TiO₂ nanotube arrays and nano-chemosensors have been developed to detect volatile organic biomarkers (VOBs) linked to TB. When combined with AI-assisted nanoarrays, these systems can accurately distinguish different TB infection stages. Although still in early development, they highlight the potential for non-invasive, rapid and cost-effective TB diagnostics, which could significantly improve global TB control (Shikha et al. 2023; Zhou et al. 2023).

Nanotechnology-based germ sensors also offer fast, sensitive and specific pathogen detection, but face challenges. Detecting very low bacterial concentrations in complex fluids like serum or cerebrospinal fluid remains difficult. Many current studies also fail to address mixed or polymicrobial infections, which are common in clinical cases.

Further research is needed to develop sensors that perform reliably in physiological fluids and complex environments. Such tools would allow early detection of infections, helping clinicians start timely treatments. Moreover, these systems could quickly differentiate drug-resistant from drug-susceptible bacteria, supporting personalised antibacterial therapy. Unlike traditional resistance testing methods such as turbidity measurement, which are accurate but time-consuming, nanoparticle-based techniques could dramatically reduce detection times, enabling faster diagnosis and improved patient outcomes. Comparison of these methods is shown in Table 1.

Table 1.

Comparative overview of nanoparticle-based bacterial detection approaches

Approach	Principle	Sensitivity/specificity	Advantages	Limitations
Immune-based sensors	Use of antibodies conjugated with nanoparticles to detect specific bacteria via colorimetric, SPR or electrochemical changes	High sensitivity; specificity depends on antibody quality	Well established; multiple formats; rapid detection possible	Expensive antibody production; stability issues
Aptasensors	Short DNA/RNA or peptide aptamers bind to bacterial epitopes with high specificity and affinity	Very high affinity and specificity; stable under various conditions	Easily synthesised; stable; cost-effective compared to antibodies	Short half-life in biological media; risk of cross-reactivity
Bacteriophage-based sensors	Phages or phage-derived proteins bind to bacterial receptors, enabling detection of live and dead cells	High stability; can differentiate live vs. dead cells; highly specific	Low cost; highly stable; adaptable by genetic engineering	Limited availability of specific phages; genetic engineering required
Array-based sensors	Pattern recognition using nanoparticle arrays generating optical/electrical fingerprints without biorecognition elements	Rapid detection; moderate specificity, relies on pattern recognition	Simple, label-free, high-throughput potential	Lower specificity compared to biorecognition sensors
Optoelectronic noses	Detection of bacterial volatile organic compounds (VOCs) using sensor arrays mimicking olfactory responses	Non-invasive, real-time detection; limited sensitivity for low bacterial counts	Portable, inexpensive, suitable for field/clinical use	Limited ability to detect mixed infections; requires further development

Table 1 summarises the major nanoparticle-enabled bacterial detection strategies, including immune-based sensors, aptasensors, bacteriophage-based sensors, array-based platforms and optoelectronic noses. Each approach is compared based on its principle of operation, sensitivity/specificity, advantages and limitations. This comparative framework highlights how nanomaterials contribute to improved sensitivity, rapidity and portability in bacterial diagnostics whilst also revealing key challenges such as stability, cost and limited applicability to mixed infections.

Nanomaterial-based bacterium biosensors for clinical trials

Nanoparticles in clinical trials and translations for antibacterial capabilities and application in bacterial detection systems

A review of nanoparticle-related clinical trials (2002–2021) and FDA-approved nanoparticle drugs (since 2016) revealed notable trends. During this period, 486 clinical studies were registered on ClinicalTrials.gov. Liposomes accounted for the largest share (44%), followed by protein-based nanoparticles (26%). amongst therapeutic agents, paclitaxel led with 23%, followed by metals (11%), doxorubicin (9%), bupivacaine (8%) and vaccines (8%). For FDA-approved formulations, polymeric nanoparticles made up 29%, liposomal systems 22% and lipid-based formulations 21% (Rajana et al. 2023).

Most research on antibacterial nanoparticles remains in vitro, with limited studies in animals or humans. Safety, toxicity and regulatory challenges continue to slow clinical translation. However, several ongoing clinical trials and growing evidence suggest that nanoparticles can effectively combat harmful microorganisms and significantly improve diagnostics and therapeutic outcomes (Wang et al. 2017). The list of the trails is mentioned in Table 2.

Table 2.

List of nanoparticles in clinical trials

S. No	Clinical trials number (date)	Composition	Phase	Status
1	NCT04365270 (2019-01-15)	Chitosan and/or Titanium dioxide NPs	III	Completed
2	NCT03186261 (2018-04-01)	Nanosilver fluoride solution	III	Completed
3	NCT04481945 (2021-06-01)	Nanosilver	IV	Completed
4	NCT05221749 (2022-03-15)	Nanosilver fluoride	III	Completed
5	NCT01950546 (2014-09)	Nanosilver fluoride	I	Completed
6	NCT00341354 (2006-01-27)	Silver NPs	II	Completed
7	NCT01258270 (2010-12)	Silver NPs	Not applicable	Completed
8	NCT02277171 (2014-12)	Silver NPs	I	Completed
9	NCT01598480 (2012-05)	Silver NPs	Not applicable	Completed
10	NCT00965198 (2009-11)	Silver NPs		Completed
11	NCT02241005 (2014-10-30)	Silver NPs	Not applicable	Completed
12	NCT04775238 (2021-02-27)	Silver and copper NPs	Not applicable	Recruiting
13	NCT01821664 (2013-05)	Silver NPs		Recruiting
14	NCT03666195 (2018-10-15)	Titanium dioxide NPs	Not applicable	Unknown
15	NCT03478150 (2018-04-01)	zinc oxide NPs	Not applicable	Unknown
16	NCT00659204 (2008-04)	Silver NPs	III	Unknown
17	NCT03635138 (2018-12-01)	Copper and zinc NPs	Not applicable	Unknown
18	NCT0221323 (NA)	Silver NPs		Unknown
19	NCT03752424 (2019-11-13)	Silver NPs	I	Unknown
20	NCT02099240 (2014-03-06)	Silver NPs	Early phase 1	Terminated
21	NCT02225158 (2014-08-15)	Silver NPs		Terminated
22	NCT03271567 (2017-09-28)	Energy-focussing porous discoidal silicon nanoparticles		Completed
23	NCT02681445 (2016-02)	Titanium dioxide nanotube	I	Completed
24	NCT03228095 (2017-07-24)	Artificially intelligent nanoarray based on gold nanoparticles and single-walled carbon nanotubes		Enrolling by invitation
25	NCT06089720 (2023-02-15)	Zinc oxide nanoparticle		Completed
26	NCT06172023 (2020-01-01)	Nano-silver, nano-zinc-oxide and chitosan nanoparticle		Completed
27	NCT04431804 (2020-06-11)	Thyme and carvacrol nanoparticle		Completed
28	NCT03271567 (201709-28)	Energy-focusing porous discoidal silicon nanoparticles		Completed

Table 2 is a list of nanoparticles currently or previously evaluated in clinical trials for antibacterial, diagnostic, and therapeutic applications, indicating their composition, trial phase, and current status

Analysis of clinical trials shows that most focus on silver nanoparticles, especially for topical and dental uses such as wound healing and caries prevention, indicating silver as the most advanced antibacterial nanomaterial. Fewer trials involve titanium dioxide, zinc oxide and copper nanoparticles, which largely remain in early or undefined stages. Some studies tested combinational formulations, like nanosilver with chitosan or zinc oxide, suggesting potential synergistic effects to boost efficacy and lower resistance risks.

Whilst several trials reported positive safety and efficacy, few advanced beyond Phase II or III, and some were terminated early due to regulatory, safety or scalability challenges. Overall, nanoparticle-based treatments show strong promise, but large-scale, late-phase studies are urgently needed to confirm their role against antimicrobial-resistant (AMR) pathogens.

Rationale for using nanoparticles as an antibacterial

Nanoparticles (NPs) have emerged as promising antibacterial agents due to their unique physicochemical properties and diverse mechanisms of action. Their high surface-area-to-volume ratio enhances interactions with microorganisms, enabling them to penetrate bacterial membranes, disrupt molecular processes and directly damage intracellular components.

NPs can also boost conventional antibiotic efficacy. For instance, gold nanoparticles (AuNPs) conjugated with antibiotics such as ampicillin, streptomycin or kanamycin significantly lower the minimum inhibitory concentrations (MICs) against both Gram-positive and Gram-negative bacteria. Synergistic effects have also been reported between fluoroquinolones and functionalised AuNPs, showing strong activity against multidrug-resistant (MDR) E. coli (Hassan et al. 2023; Lee et al. 2019).

The antibacterial activity of NPs depends on factors such as size, shape, surface charge and chemical modifications, which influence both synthesis behaviour and bacterial interactions. When combined with antibiotics, NPs offer multifaceted mechanisms that enhance bacterial clearance and reduce resistance development, making them powerful tools against MDR pathogens.

Metallic nanoparticles, in particular, have demonstrated broad-spectrum antibacterial activity in both in vitro and in vivo studies (Prasanna et al. 2021). Their effectiveness stems from their ability to directly interact with bacterial cells, stimulate host immune responses, prevent biofilm formation, generate reactive oxygen species (ROS) and inhibit key bacterial processes such as RNA and protein synthesis (Kumar et al. 2022).

NPs are also used in antimicrobial coatings for implants, wound dressings, bone cement and dental materials, providing localised, sustained drug delivery. Additionally, as drug carriers, they transport higher concentrations of antimicrobials directly to infection sites, increasing treatment efficacy and minimising systemic side effects. By integrating NPs with conventional antibiotics, it is possible to combat antimicrobial resistance (AMR) through synergistic and multi-targeted mechanisms, offering a promising strategy to address the global rise of drug-resistant infections (Das et al. 2024).

Mechanistic insight into antibacterial effects of NPs

Multiple mechanisms explain the antimicrobial effects of nanoparticles (NPs). They can bind to bacterial surfaces or accumulate inside cells through electrostatic, hydrophobic, van der Waals, receptor–ligand or membrane-crossing interactions (Mendes et al. 2022). Whilst these antibacterial mechanisms are well established at the laboratory scale, recent studies emphasise that their effectiveness and translational relevance are strongly influenced by nanoparticle physicochemical properties, biological microenvironment and dose-dependent toxicity, highlighting the need for mechanism-specific optimisation rather than a universal antibacterial approach (Savadi et al. 2025; Tang et al. 2025).

Figure 2 illustrates these proposed mechanisms underlying NP antibacterial activity.

Fig. 2.

Mechanisms of antibacterial nanoparticle. Nanoparticles (yellow) interact with bacterial cells, leading to ROS generation, membrane disruption, enzyme inhibition, ribosome and mitochondrial dysfunction, DNA damage, efflux pump inhibition and toxin neutralisation

Cell membrane damage

Researchers synthesised thymol-loaded chitosan nanoparticles (TCNPs) and evaluated their antibacterial efficacy against Xanthomonas campestris pv. campestris (Xcc), a plant pathogen causing black rot in cruciferous crops. Ultrastructural analysis showed severe membrane damage in TCNP-treated Xcc cells, leading to the release of intracellular contents, confirming strong antibacterial activity (Chakraborty et al. 2024). Zinc oxide nanoparticles (ZnO NPs) were tested against Escherichia coli, Staphylococcus aureus, Pseudomonas aeruginosa and Bacillus subtilis. Fluorescence microscopy revealed that ZnO NPs did not affect bacterial cell division machinery but caused cytoplasmic membrane damage in ~ 70% of cells within 15 min, demonstrating rapid antibacterial action (Mendes et al. 2022; Shikha et al. 2023).

Contact-active copper nanoparticles coated with polydopamine (Cuf-TMB@PDA) showed strong interaction with negatively charged bacterial membranes, enabling controlled release of Cu(II) ions. This, combined with free radicals, produced a synergistic antibacterial effect (Zhou et al. 2023). Silver-carbon nanoparticles (AgNPs@C) were generated using a single-spark electrical arc. Compared with Ceftazidime, AgNPs@C exhibited superior antibacterial activity against P. aeruginosa, causing extensive cell death and lysis, as confirmed by confocal and TEM imaging. Gene expression analysis showed inhibition of virulence-associated genes (fimH, rmpA, mrkA) (Elwakil et al. 2024).

Swarming magnetic nanorobots made of Fe₃O₄@PDA-TA effectively targeted complex infections. They exhibited excellent photothermal conversion under near-infrared (NIR) light and navigated deep tissue channels to disrupt bacterial membranes through tannic acid (TA)-mediated adhesion (Si et al. 2024). Magnesium hydroxide [Mg (OH)₂] nanoparticles induced oxidative stress and membrane damage in sulphate-reducing bacteria (SRB). Similarly, solid lipid nanoparticle (Xia et al. 2024). SLN-Encapsulated nisin Z showed a fourfold lower minimum inhibitory concentration (MIC) against S. aureus compared to free nisin Z by enhancing its binding to lipid II on the bacterial membrane (Ratrey et al. 2024).

Four copper-resistant Pseudomonas strains (P. lactis, P. panacis, P. veronii UKR3 and UKR4) were tested against Cu₂O and CuO nanoparticles. SEM and TEM images confirmed severe membrane rupture, morphological deformation and vesiculation (Havryliuk et al. 2024).

Finally, studies using model membranes and both Gram-positive (S. aureus) and Gram-negative (P. aeruginosa) bacteria revealed how nanoparticles damage membranes. Hydrophilic and hydrophobic gold nanoparticles (AuNPs) with different shapes were studied using a microfluidic device. Quasi-spherical AuNPs showed stronger binding, causing membrane strain, rupture and bacterial cell death (Linklater et al. 2020). Although membrane disruption enables rapid bactericidal activity, non-selective membrane damage may also affect host cell membranes, underscore the importance of surface functionalisation and target strategies to improve bacterial selectivity and minimise cytotoxicity during clinical translation (Khalifa et al. 2025).

Bacterial cell metabolism

Blue luminescent, aminated and carboxylated graphene quantum dots (GQDs) were tested for antibacterial activity against Escherichia coli. GQD types generated reactive oxygen species (ROS) and inhibited bacterial metabolism without significantly altering overall cell structure. Prolonged blue light exposure enhanced ROS production, increasing antibacterial activity. Additionally, GQDs also disrupted eukaryotic cell membranes and facilitated antibiotic uptake, leading to a marked reduction of E. coli load in infected CaCO-2 cells, highlighting their potential as an adjunct therapy (Rosato et al. 2024). However, prolonged metabolic interference and enhanced ROS generation may also influence host cellular pathways, indicating that careful dose optimisation and temporal control are critical for safely translating metabolism-targeting nanoparticles into clinical applications (Zhang et al. 2025).

Ros production

Silver peroxide nanoparticles (Ag₂O₂ NPs) were developed with a controlled ROS release system, where ultrasound and near-infrared (NIR) light regulate the production of antibacterial silver ions (Ag⁺) and ROS. In both in vitro and in vivo studies, Ag₂O₂ NPs destroyed over 99.9999% of bacteria and biofilms within 10 min and significantly accelerated the healing of multidrug-resistant Staphylococcus aureus–infected skin wounds (Bi et al. 2022). These nanoparticles also showed excellent cytocompatibility and hemocompatibility, making them suitable for clinical use. Biocompatible copper nanoparticles (CuNPs-K), synthesised using keratin protein from chicken feathers, were tested against multidrug-resistant (MDR) uropathogens such as E. coli and Enterococcus faecalis in both single and mixed cultures. CuNPs-K killed bacteria by targeting membranes and DNA, with ROS generation as the primary antibacterial mechanism (Vishakha et al. 2023). Similarly, zinc–magnesium bimetal nanoparticles (ZnMgNPs) disrupted bacterial membranes and caused oxidative damage, leading to cell death in Xanthomonas oryzae pv. oryzae (Xoo), a major rice pathogen (Sahoo et al. 2024). Zinc oxide nanoparticles (ZnONPs) functionalised with polyethylene glycol (PEG) showed improved antibacterial efficacy and photocatalytic ROS generation compared to non-functionalised ZnONPs, with higher performance at increased concentrations (Liu et al. 2024).

A unique mechanism was observed with Cu₃SbS₃ nanoparticles, which selectively targeted bacterial cells whilst sparing mammalian cells. These nanoparticles bind to oxygen atoms in N-acetylmuramic acid of bacterial cell walls and to copper ions within the Cu₃SbS₃ lattice, initiating a cascade of ROS reactions:

• Generation of superoxide radicals (O₂•–) by Cu₃SbS₃ NPs.

• Conversion of O₂•– to hydrogen peroxide (H₂O₂) by bacterial superoxide dismutase.

• Catalysis of H₂O₂ into hydroxyl radicals (•OH) and singlet oxygen (¹O₂).

These ROS species attack bacterial membranes and intracellular components locally, minimising harm to surrounding mammalian cells. Additionally, this process depletes glutathione and disrupts bacterial antioxidant defences, amplifying cell death (El-Samahy et al. 2024). Despite their potent antibacterial efficacy, ROS-generating nanoparticles require precise control over ROS intensity and spatial localisation, as excessive oxidative stress may induce inflammatory responses or off-target tissue damage, representing a key translational challenge (Ding et al. 2026).

Efflux pump

Researchers explored how reserpine, a known efflux pump inhibitor (EPI), affected photoreactivation of pathogens in the presence of silver nanoparticles (AgNPs) and methylene blue (MB). Blocking the AcrAB-TolC efflux pump with reserpine improved MB retention, thereby enhancing antibacterial efficacy (Allamyradov et al. 2024).

Additionally, the effects of silver nanoparticles (Ag⁰-NPs) and silver ions (Ag⁺) on antibiotic resistance genes (ARGs) and biofilm formation were investigated in the Yangtze Estuary. Continuous treatment with 10 µg/L Ag⁰-NPs and Ag⁺ significantly reduced ARG abundance, particularly in Betaproteobacteria. KEGG pathway analysis suggested that these nanoparticles modulate ARG expression through the arlS/silS-arlR signalling pathway and the beta-lactam resistance system, indicating their potential to control biofilm-associated resistance (Guo et al. 2024). Targeting efflux pump systems using nanoparticle-assisted strategies represents a promising approach to restore antibiotic susceptibility; however, the long-term impact of such interventions on microbial community dynamics and resistance evolution remains insufficiently understood (Savadi et al. 2025).

NP activity against bacterial toxins

Bacteria secrete toxins that damage host tissues, promote invasion and help evade immune defences. These toxins play a central role in bacterial infections. Nanoparticles (NPs) have been engineered to bind and neutralise these toxins, reducing tissue destruction and inflammation. Researchers developed a toxin-responsive NP nanoreactor that degrades bacterial toxins in vivo, directly neutralising their effects. Research on synthesised reactive metal boride NPs that capture lipopolysaccharides (LPS) and peptidoglycans (PGN), reducing inflammation and accelerating wound healing (Mammari et al. 2022). This dual-function system simultaneously neutralises endotoxins and exotoxins at infection sites, improving therapeutic outcomes (Hu et al. 2013).

Influence of physicochemical properties on antibacterial activity

The physicochemical properties of nanoparticles (NPs) strongly influence their antimicrobial activity. Size and shape determine membrane penetration and surface interactions, with smaller or anisotropic particles showing higher antibacterial efficiency due to increased surface area and closer contact with bacterial membranes.

Surface charge is also critical; positively charged NPs bind strongly to negatively charged bacterial cell surfaces, enhancing membrane disruption and permeability. Functional coatings or chemical groups can further target specific bacterial components, such as lipopolysaccharides in Gram-negative or teichoic acids in Gram-positive bacteria, improving uptake and bactericidal action. Redox-active NPs like silver (Ag), zinc oxide (ZnO) and titanium dioxide (TiO₂) generate reactive oxygen species (ROS), disrupting bacterial redox balance and causing oxidative damage to proteins, lipids and nucleic acids. In defence, bacteria may upregulate stress-response genes and efflux pumps to counter NP-induced damage. Understanding these nano-bio-interactions is essential for optimising NP design to enhance efficacy whilst minimising resistance development (Meng et al. 2022). Accordingly, rational nanoparticle design that integrates physicochemical optimisation with biological safety, scalability and regulatory considerations is essential for advancing antibacterial nanotechnologies toward clinical implementation (Tang et al. 2025).

To facilitate a critical comparison of major nanoparticle platforms, Table 3 summarises the antibacterial mechanisms, advantages, limitations and key translational barriers associated with different nanoparticle systems (Khalifa et al. 2025; Savadi et al. 2025; Tang et al. 2025; Zhang et al. 2025).

Table 3.

Comparative analysis of major nanoparticle systems for antibacterial applications

Nanoparticle system	Key antibacterial mechanisms	Major advantages	Key limitations	Translational barriers
Metallic nanoparticles (Ag, Cu, ZnO)	Membrane disruption, ROS generation, protein/DNA damage	Rapid and strong antibacterial activity; broad-spectrum efficacy	Cytotoxicity to host cells; oxidative stress; environmental accumulation	Dose control, long-term safety, regulatory toxicity concerns
Polymeric nanoparticles (chitosan, PLGA)	Membrane interaction, controlled drug release, metabolic interference	High biocompatibility; tunable release; reduced systemic toxicity	Lower intrinsic antibacterial activity; often require drug loading	Manufacturing scalability; reproducibility
Lipid-based nanoparticles (SLNs, liposomes)	Membrane fusion, enhanced drug delivery	Excellent biocompatibility; clinical familiarity	Stability issues; limited standalone antibacterial effect	Storage stability; large-scale production
Carbon-based nanoparticles (graphene, CQDs)	ROS generation, metabolic inhibition, membrane stress	High surface area; multifunctionality	Potential cytotoxicity; inconsistent biodegradation	Safety validation; regulatory uncertainty
Hybrid/biomimetic nanoparticles	Combined mechanisms (ROS + targeting + delivery)	Enhanced selectivity; reduced toxicity; multifunctional	Structural complexity; synthesis challenges	Scale-up, cost, regulatory approval complexity

Challenges and future perspectives in clinical translation of nanoparticle therapies

Although nanoparticles (NPs) show significant promise for the treatment of bacterial infections, several critical challenges must be addressed before their widespread clinical adoption. These challenges include:

• Determining optimal dosage for different types of infections,

• Identifying the most effective routes of administration and

• Assessing potential toxicity of NPs under both short- and long-term exposure scenarios.

• Recent translational reviews highlight that dose-dependent toxicity, biodistribution and immune interactions remain major bottlenecks limiting clinical progress of antibacterial nanomedicines (Tang et al. 2025; Zhang et al. 2025).

Compared to traditional antibiotics, NPs offer distinct advantages in overcoming antimicrobial resistance due to their unique physicochemical properties and multimodal mechanisms of action. At present, the most advanced clinical applications involve topical formulations, coatings for medical devices, wound dressings and antimicrobial textiles, where local delivery minimises systemic exposure and toxicity risks (Khalifa et al. 2025; Savadi et al. 2025).

However, systemic administration of NPs introduces additional complexities related to biodistribution, immune recognition and off-target accumulation. To accelerate clinical translation, recent studies emphasise the need to establish standardised manufacturing protocols for scalable and reproducible nanoparticle production, comprehensive physicochemical characterisation linked to biocompatibility, harmonised nanotoxicological testing frameworks and validated protocols enabling meaningful comparison between in vitro and in vivo outcomes (Ding et al. 2026; Savadi et al. 2025; Tang et al. 2025).

Future preclinical studies must rigorously evaluate NP safety, therapeutic efficacy and dosing regimens using clinically relevant endpoints. In parallel, economic feasibility and regulatory considerations—including manufacturing costs, batch-to-batch reproducibility and long-term safety monitoring—must be addressed to justify clinical investment. Emerging biomaterial-driven and hybrid antibacterial strategies, including phage–material systems, may complement nanoparticle therapies but will similarly require robust regulatory and cost-effectiveness assessments before clinical adoption (Tang et al. 2025; Zhou et al. 2026).

Conclusion

Nanotechnology has emerged as a powerful and versatile approach for both the rapid detection and effective treatment of bacterial infections. This review highlights the transformative potential of nanoparticle-based platforms in addressing the growing global challenge of antimicrobial resistance by integrating advanced diagnostics with multifaceted antibacterial mechanisms.

Nanoparticle-enabled detection systems, including immunosensors, aptasensors, bacteriophage-based sensors, array-based platforms and optoelectronic sensing technologies, offer rapid, sensitive and accurate identification of bacterial pathogens in clinical and environmental settings. Emerging strategies such as flagella-specific binding probes further expand diagnostic capabilities, although their translational development remains limited and warrants deeper investigation.

Unlike conventional antibiotics, nanoparticles exert antibacterial activity through multiple complementary mechanisms, including membrane disruption, metabolic interference, reactive oxygen species (ROS) generation, efflux pump inhibition and toxin neutralisation. Additional evidence suggests that nanoparticles may also interfere with intracellular targets such as the electron transport chain, ribosomes, mitochondria and bacterial DNA, revealing new avenues for antimicrobial intervention beyond traditional drug targets.

From a translational perspective, nanoparticle formulations are steadily advancing from laboratory studies toward preclinical and clinical evaluation. These systems demonstrate considerable promise in combating multidrug-resistant pathogens, improving drug delivery efficiency and enabling combination therapies with reduced toxicity and enhanced therapeutic outcomes.

Despite these advances, several challenges must be addressed before widespread clinical adoption can be achieved. Future research should prioritise standardised physicochemical characterisation, dose–response optimisation and harmonised nanotoxicological assessment to ensure safety and reproducibility. In parallel, scalable and cost-effective manufacturing strategies, regulatory alignment and clinically relevant pharmacokinetic and pharmacodynamic studies must be integrated early in nanoparticle development. Emphasis on eco-friendly synthesis routes and biodegradable nanomaterials will further enhance sustainability and long-term applicability.

Overall, nanotechnology holds significant potential to reshape bacterial disease management by unifying detection, treatment and prevention strategies. Addressing current translational barriers through interdisciplinary collaboration amongst material scientists, microbiologists, clinicians and regulatory bodies will be essential to advance nanoparticle-based antibacterial technologies from bench to bedside.

Author contribution

VKR conceived and designed the overall concept of the review, supervised the project at every stage, and finalized the manuscript. AM and JM were primarily responsible for conducting the comprehensive literature search, retrieving and organizing relevant data, and drafting the initial versions of specific sections of the manuscript. KYNL, KP, KH, and SS contributed by preparing the figures and tables, formatting and cross-checking references, and providing assistance with the overall structuring and critical editing of the text. VKR, together with AM and JM critically analysed the content and revised the manuscript to enhance clarity, coherence, and scientific depth, ensuring that important intellectual aspects were fully addressed. All authors contributed to the refinement of the final draft, read the manuscript thoroughly, and approved the final version for submission.

Funding

The funding for this work was provided by the Shri Vishnu College of Pharmacy, Bhimavaram-534202.

Data availability

This article is a review paper and does not report any new experimental or clinical data. All information discussed in this manuscript is derived from previously published studies, which are cited in the reference list.

Declarations

Ethics and consent to participate

Not applicable.

Competing Interests

The authors declare no competing interests.