Study design

This systematic review followed PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) guidelines, covering article items including title, abstract, introduction, methods, results, and discussion. The study protocol included research questions, aims, inclusion/exclusion criteria, and a methodological approach. A PRISMA 2020 Checklist (S1) was used to ascertain that this systematic review followed PRISMA guidelines.

Review questions

• What is the efficacy of nanotechnology-based antimicrobial agents against AMR Gram-positive bacteria?

• What types of nanomaterials have been used to target Gram-positive bacteria?

• What are the mechanisms of action of these nanotechnology-based antimicrobials?

• What are the limitations, toxicity concerns, and future potentials of these technologies?

Search strategy

A comprehensive literature search was conducted using PubMed, Scopus, Google Scholar, and HINARI to identify studies published between 2014 and 2024. This timeframe was chosen to capture a decade of significant advances in nanomaterial-driven antimicrobial research and its application against AMR pathogens. The search strategy employed precise Boolean strings, including combinations of keywords and MeSH terms such as “nanotechnology” OR “nanoparticle” OR “nanomaterial” AND “antimicrobial resistance” OR “AMR” OR “antibiotic resistance” AND “Gram-positive bacteria”. Boolean operators (AND, OR) and truncations were systematically applied to maximize the retrieval of relevant records, specifically evaluating the effectiveness of nanomaterial-based antimicrobials in combating AMR, specifically in Gram-positive bacteria, while filtering duplicates. Google Scholar results were filtered for quality by prioritizing peer-reviewed journal articles published in reputable and indexed journals. Studies from non-indexed or low-impact sources were excluded after assessing methodological rigor and citation relevance. In addition to database searching, manual screening and backward citation tracking were performed to identify additional studies referenced in the bibliographies of eligible articles. Two researchers (UOA and OJ Okesanya) independently conducted database searches and preliminary analyses to ensure consistency and completeness of retrieved data.

Eligibility criteria

Included studies comprised experimental preclinical designs (in vitro, in vivo, or combined) and clinical observational or interventional studies that evaluated the antibacterial effects of nanomaterials against Gram-positive bacteria.

The following inclusion criteria were established using the population, intervention, comparison, and outcome (PICO) framework:

Population (P): Gram-positive bacteria exhibiting resistance to conventional antibiotics.

Intervention (I): Nanomaterial-based antimicrobial agents.

Comparison (C): Conventional antibiotics or untreated controls.

Outcome (O): Antimicrobial efficacy, bacterial load reduction, biofilm disruption, toxicity, and resistance modulation.

Harnessing nanomaterials to overcome AMR in Gram-positive bacteria

This review included studies that focused on utilizing nanomaterial-based antimicrobial agents to combat Gram-positive AMR bacteria. Eligible studies were published between 2014 and 2024 and in English. Studies that did not provide relevant data or focused solely on other microorganisms were excluded. Qualitative studies, preprints, narrative and systematic review articles, editorials, commentaries, conference abstracts, and data from grey and unpublished sources were excluded due to inconsistency in reporting. Data on nanomaterial-based agents, mechanisms of action, and key findings were extracted.

Study selection process

Study selection was conducted in a two-stage process by two independent reviewers (KBO and OBA) who screened titles and abstracts for relevance based on predefined inclusion and exclusion criteria. Full-text screening was conducted for potentially eligible articles. Any disagreements were resolved through discussion or consultation with a third reviewer (CNC). Manual backward citation screening was also applied to ensure comprehensiveness. To minimize bias, no restrictions were placed on author affiliation, journal of publication, or study outcomes. Only studies that met the inclusion criteria were considered. Paper titles reported in tables were preserved or paraphrased for clarity and neutrality.

Data extraction, synthesis, and statistical analysis

Data from eligible studies were independently extracted by two reviewers (AKY and KOT) using a standardized form that included nanomaterials used, pathogen targeted, antimicrobial mechanism of action, study type, key findings, advantages of nanomaterials over conventional agents, and limitations. Nanomaterials were categorized based on their chemical composition and synthesis origin into one of seven classes: metal-based, metal oxide-based, polymeric, lipid-based, carbon-based, biologically derived, or inorganic-based. This classification enabled clearer interpretation of mechanisms of action and antibacterial effectiveness across material types. All extracted data were verified for consistency against the original publication. Inconsistencies were resolved through consensus. Descriptive analysis was performed to summarize trends in nanomaterial types, pathogen types, and in vitro/in vivo outcomes. As this is a descriptive systematic review, no inferential statistical tests were applied.

Quality assessment

The Joanna Briggs Instituteʼs Critical Appraisal Checklist was used to evaluate the methodological quality of the included studies, with an 8-point rating system and a minimum score of 50% required.

Overview of included studies

A total of 1,530 articles were identified through database searches. After removing 125 duplicates, 1,405 records were screened by title and abstract, excluding 1,052 that did not meet the inclusion criteria. An additional 18 studies were excluded due to non-material interventions, focus on Gram-negative bacteria, review articles, or incomplete data. Of 335 full-text articles assessed for eligibility, a total of 204 were excluded, of which (n = 108) were for inappropriate methodology, article type (reviews/commentaries, n = 62), or mixed bacterial outcomes without separable Gram-positive data (n = 34). Ultimately, 131 studies were included in the final synthesis (Figure 1, Table 1 [20–150]). Included studies were primarily in vitro, with China and India accounting for the highest representation (16% each). Many studies utilized green-synthesized nanoparticles from plant extracts. Some employed composite or hybrid nanoparticles, including polymer-coated, drug-loaded, or biologically stabilized forms. Targeted Gram-positive pathogens included Staphylococcus aureus (MRSA and MSSA) [20, 22, 24], other Staphylococcus spp. [29, 45], Streptococcus spp. [61, 64], Listeria spp. [82], Clostridium perfringens [109], Bacillus spp. [39, 44], and Enterococcus spp. [93, 94], highlighting the broad-spectrum activity of nanomaterials against resistant strains.

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Figure 1. PRISMA flowchart of included studies. Adapted from [151]. © 2024-2025 the PRISMA Executive. Licensed under a CC BY 4.0. PRISMA: Preferred Reporting Items for Systematic Reviews and Meta-Analyses.

Nanomaterials used, class, and their antimicrobial efficacy

Nanomaterials were classified as metallic (AgNPs, AuNPs, CuO NPs, ZnO NPs), polymeric (chitosan, PLGA), lipid-based (liposomes, solid lipid NPs), and carbon-based (graphene oxide, CNTs) [11, 15]. AgNPs, often metal-based and being the most frequently reported in over 50 studies, exhibited strong bactericidal and antibiofilm activity via ROS production, membrane disruption, and interference with bacterial metabolism [26, 29, 31–34, 39, 57, 68, 114, 146]. AuNPs, frequently functionalized or combined with drugs, enhanced antimicrobial and wound-healing potential [21, 34, 40, 63, 67, 72, 101]. ZnO NPs and Cu/CuO NPs demonstrated ROS-mediated antibacterial and antibiofilm effects, often synergistic with antibiotics [73, 78, 94, 119, 121]. Some studies explored hybrid or functionalized nanomaterials with advanced properties. For example, MXF@UiOUBIPEGTK, a biologically derived ROS-responsive system, enabled targeted drug release in oxidative infection environments [52]. Polymeric nanoparticles, including chitosan and PLGA-based formulations, offered controlled antibiotic release and improved biofilm inhibition, supporting long-term antimicrobial therapy [108]. Collectively, these nanomaterials enhanced antibacterial effectiveness, often achieving substantial bacterial suppression at low antibiotic doses, thus mitigating resistance development, demonstrating broad-spectrum activity, and reducing high-dose side effects. Notably, biogenic CuNPs and ZnO NPs exhibited strong synergistic activity against MRSA, producing significantly larger inhibitory zones against Gram-positive pathogens such as Staphylococcus aureus, S. saprophyticus, S. sciuri, and S. epidermidis [28, 42, 46, 123, 127, 132, 142, 146, 149]. Biologically derived AgNPs, including CAgNPs, disrupted biofilms in both S. aureus and MRSA strains, highlighting their potential in treating chronic Gram-positive infections [30, 138].

Mechanisms of action of nanomaterials

Nanoparticles exert antimicrobial and therapeutic effects against Gram-positive bacteria through multiple physical, chemical, and biological mechanisms (Table 1). The most frequently reported mechanism is bacterial membrane disruption, which increases permeability, causes leakage of cytoplasmic components (e.g., DNA, ions, proteins), and ultimately leads to cell lysis [20, 29, 31, 37, 45, 60, 61]. ROS generation is another key mechanism, inducing oxidative stress that damages lipids, proteins, and DNA, resulting in significant bacterial mortality [24, 31, 42, 86, 93, 100, 113, 118, 140]. Intracellular interference by nanoparticles can inhibit replication, transcription, and protein synthesis, often through DNA interaction or ATP depletion [50, 69, 125]. Some nanoparticles disrupt bacterial enzymes and metabolic pathways, causing energy depletion and cell death [24, 139]. For biofilm prevention and eradication, particularly in persistent infections like MRSA, nanoparticles prevent surface adhesion, degrade the EPS matrix, and downregulate biofilm-associated genes [31, 47, 52, 133, 146]. Stimulus-responsive drug delivery allows nanoparticles to release therapeutic agents in response to bacterial cues such as enzymes, pH, enhancing specificity and minimizing side effects [30, 71, 74]. The release of metal ions (Ag⁺, Zn²⁺, Cu²⁺) further disrupts thiol-containing proteins, inhibits enzymes, and generates ROS, intensifying antibacterial activity [33, 80, 94, 98, 149]. Additionally, some nanoparticles cause localized physical damage via photothermal or electromagnetic effects, leading to protein denaturation and membrane rupture [60, 99, 136].

Toxicity assessment in included studies

Forty-five of the included 131 studies reported toxicity assessments or safety considerations at either cellular, preclinical, or in vivo levels. Most of these involved in vitro cytotoxicity assays on mammalian cell lines, while a smaller number examined hemolytic activity or animal model safety. A recurring finding was dose-dependent toxicity, where nanoparticles were biocompatible at lower concentrations but cytotoxic at higher doses [23, 28, 86, 98, 134, 140]. Metal-based nanoparticles, particularly silver and CuO, were most frequently associated with such safety concerns [28, 41, 87, 98, 121, 140], whereas polymeric and lipid-based formulations generally showed better tolerance. Despite these encouraging results, standardized protocols and long-term safety studies remain scarce.

Advantages of nanomaterial-based antimicrobial agents over conventional methods

Green-synthesized nanoparticles offer biocompatibility, lower toxicity, and environmental safety, making them a sustainable alternative to conventional antibiotics [48, 79, 112, 113]. They exhibit strong activity against MDR Gram-positive bacteria, including MRSA and Enterococcus faecalis, even in strains resistant to vancomycin and β-lactams [21, 48, 111, 117]. Their broad-spectrum efficacy arises from simultaneous targeting of multiple bacterial components, such as membranes, DNA, and intracellular proteins, effectively overcoming resistance mechanisms [77, 111, 117]. Studies show minimal resistance development after repeated bacterial exposure, highlighting a lower propensity for resistance compared to traditional antibiotics [120, 122, 142]. Synergistic combinations of nanoparticles with conventional antibiotics can restore sensitivity in resistant strains [48], enhance antibacterial efficacy [65], reduce MICs [57], and allow lower drug dosages, thereby minimizing toxicity [45]. Unlike standard antibiotics, which often fail against biofilms, nanoparticles, especially ROS-generating types, effectively prevent biofilm formation and disrupt preformed biofilms [79, 133, 146]. Beyond antimicrobial activity, some nanoparticles promote wound healing and tissue regeneration, such as epigallocatechin gallate-ferric complex nanoparticles and photo-crosslinked chitosan/methacrylate hyaluronic acid nanoparticles [44, 99]. AuNPs and SWCNTs@mSiO₂TSD@Ag also support tissue repair while maintaining antibacterial potency [33]. Several nanoparticles additionally enhance therapeutic value through targeted drug delivery, biosensing, or imaging [48, 70, 86]. Stimuli-responsive nanoparticles release drugs in response to bacterial cues such as pH shifts, enzymes, or oxidative stress, allowing precise delivery to infection sites with minimal impact on healthy tissues [30, 52, 71, 74].

Clinical translation and policy pathways

Widespread implementation requires integration into national and global AMR frameworks. World Health Organization (WHO), Centres for Disease Control and Prevention, and the European Medicines Agency should include nanomedicine strategies in upcoming AMR action plans, with the 2026 WHO Global Action Plan offering a key opportunity to integrate these innovations into policy [179]. A Global Nanomedicine Regulation and Evaluation Framework, modelled after International Council for Harmonization and the International Coalition of Medicines Regulatory Authorities guidelines, could harmonize safety, efficacy, and quality standards [180–182]. Establishing good manufacturing practice (GMP)-compliant nanomedicine hubs and mobile synthesis labs will support scalable production, as demonstrated by Sri Lanka Institute of Nanotechnology and African mRNA tech hubs [183]. Pooled procurement mechanisms such as the PAHO Revolving Fund and EAC framework can enhance access and affordability [184, 185].

Translational barriers and future recommendations

Major translational barriers include the lack of standardized toxicity protocols, limited pharmacokinetic-pharmacodynamic data, and variability in nanomaterial synthesis. Although microfluidic and GMP-compliant platforms improve reproducibility, their use is still constrained by cost and infrastructure [186, 187]. Regulatory frameworks are also emerging slowly, with no universally defined approval pathways for nano-antimicrobials [188, 189]. Current research highlights the promise of nanomaterial-based antimicrobials in combating Gram-positive AMR, particularly through their ability to target biofilms and evade traditional resistance mechanisms [190, 191]. However, significant challenges remain, including the lack of standardized manufacturing processes, which leads to heterogeneity in nanoparticle synthesis, size, and functionalization, ultimately hampering reproducibility and cross-study comparisons [192, 193]. The need for scalable, cost-effective, and standardized production methods supported by international guidelines is emphasized to improve quality control and accelerate clinical translation, while also addressing economic feasibility and access in low resource settings [194, 195].

There is growing concern that bacteria may develop resistance to nanomaterials themselves, as sub-lethal exposure can induce adaptive responses such as biofilm reinforcement, efflux pump upregulation, and antioxidant defense activation [196, 197]. Long-term surveillance, nanoparticle rotation, combination therapies, and stimuli-responsive delivery systems are proposed strategies to mitigate this risk [193, 198]. Comprehensive toxicity studies, including long-term and environmental effects, are also needed under standardized protocols to ensure safety risk [198]. Translation to clinical use will also require well-designed trials with standardized endpoints that compare nanoparticle therapies directly with existing antibiotics [199]. Ultimately, coordinated efforts across scientific, medical, policy, and industrial sectors, along with the establishment of international regulatory frameworks and GMP-compliant hubs, are seen as essential for harmonizing safety and efficacy standards and ensuring global access to these advanced therapies [195].