Eco-friendly cleanup: the power of nano-bioremediation in microplastic management

Limpeza ecológica: o poder da nanobiorremediação no gerenciamento de microplásticos

Abstract

Microplastic (MP) pollution has emerged as a defining environmental challenge of the 21st century, threatening ecosystems, food security, and human health at an unprecedented scale. Conventional remediation methods—such as filtration, coagulation, and advanced oxidation—remain inefficient, energy-intensive, and incapable of addressing nanoscale fragments or preventing secondary contamination. This review provides a comprehensive and forward-looking synthesis ofnanoparticle-assisted bioremediation, an emerging paradigm that integrates microbial enzymatic degradation with engineered and green-synthesized nanomaterials to achieve sustainable plastic depolymerization. We critically examine how magnetic nanoparticles enable rapid adsorption and recovery, how photocatalytic metal oxides (TiO₂, ZnO, Fe₂O₃, CeO₂) and plasmonic hybrids generate reactive oxygen species to oxidatively cleave polymer chains, and how nano–bio hybrid systems stabilize enzymes, enhance substrate accessibility, and accelerate mineralization into CO₂, H₂O, and biomass. Special emphasis is placed on green-synthesized nanoparticles derived from plants and microbes, which offer enhanced environmental compatibility and catalytic efficiency. The review also evaluates the mechanistic underpinnings, kinetic parameters, and techno-economic feasibility of these systems, identifying critical challenges related to nanoparticle aggregation, enzyme instability, and ecological safety. By uniting insights from nanotechnology, microbiology, and environmental engineering, this work delineates a strategic roadmap toward biodegradable, multifunctional nanomaterials and biofilm-enhanced hybrid reactors capable of large-scale deployment. Nano-bioremediation represents not merely an incremental advance but a transformative step toward a circular, low-carbon bioeconomy, offering a realistic and scalable pathway to mitigate global microplastic pollution and restore environmental integrity.

Keywords:
microplastics; nanoparticles; nano-bioremediation; green synthesis; polymer degradation

Resumo

A poluição por microplásticos (MP) emergiu como um desafio ambiental crucial do século XXI, ameaçando ecossistemas, segurança alimentar e saúde humana em uma escala sem precedentes. Os métodos convencionais de remediação − como filtração, coagulação e oxidação avançada − permanecem ineficientes, consomem muita energia e são incapazes de lidar com fragmentos em nanoescala ou prevenir a contaminação secundária. Esta revisão fornece uma síntese abrangente e voltada para o futuro da biorremediação assistida por nanopartículas, um paradigma emergente que integra a degradação enzimática microbiana com nanomateriais projetados e sintetizados de forma ecológica para alcançar a despolimerização sustentável do plástico. Analisamos criticamente como nanopartículas magnéticas permitem adsorção e recuperação rápidas, como óxidos metálicos fotocatalíticos (TiO₂, ZnO, Fe₂O₃, CeO₂) e híbridos plasmônicos geram espécies reativas de oxigênio para clivar oxidativamente cadeias poliméricas, e como sistemas híbridos nanobio estabilizam enzimas, aumentam a acessibilidade do substrato e aceleram a mineralização em CO₂, H₂O e biomassa. Damos especial ênfase a nanopartículas sintetizadas por via verde, derivadas de plantas e microrganismos, que oferecem maior compatibilidade ambiental e eficiência catalítica. A revisão também avalia os mecanismos subjacentes, os parâmetros cinéticos e a viabilidade técnico-econômica desses sistemas, identificando desafios críticos relacionados à agregação de nanopartículas, à instabilidade enzimática e à segurança ecológica. Ao unir conhecimentos de nanotecnologia, microbiologia e engenharia ambiental, este trabalho delineia um roteiro estratégico para nanomateriais biodegradáveis ​​e multifuncionais, e biorreatores híbridos aprimorados por biofilme, capazes de implantação em larga escala. A nanobiorremediação representa não apenas um avanço incremental, mas um passo transformador em direção a uma bioeconomia circular e de baixo carbono, oferecendo um caminho realista e escalonável para mitigar a poluição global por microplásticos, e restaurar a integridade ambiental.

Palavras-chave:
microplásticos; nanopartículas; nanobiorremediação; síntese verde; degradação de polímeros

1. Introduction

Microplastics (MPs), defined as synthetic polymer fragments smaller than 5 mm, have emerged as critical global contaminants due to their persistence, ubiquity, and ecological risk. They originate as primary microplastics, intentionally produced for industrial and domestic applications such as cosmetics, textiles, and abrasives, or as secondary microplastics, derived from the environmental fragmentation and photodegradation of larger plastic debris (Mathew et al., 2024). Their minute dimensions, hydrophobicity, and buoyancy facilitate widespread dispersion across terrestrial, aquatic, and atmospheric systems, where they interact with biotic and abiotic matrices (Mathew et al., 2024). The intrinsic resistance of polymeric C–C and C–O backbones to biodegradation results in long environmental residence times, enabling MPs to act as carriers for heavy metals, plasticizers, and persistent organic pollutants, thus promoting contaminant bioavailability, trophic transfer, and biomagnification through food webs (Kumar and Pal, 2025). In addition, abiotic oxidation and microbial degradation processes of MPs contribute to greenhouse gas emissions, further linking plastic pollution to climate change (Amparán et al., 2025). The detection of MPs in sediments, surface and groundwater, atmospheric fallout, and wastewater treatment effluents underscores their role as pervasive and recalcitrant pollutants that compromise ecological and human health.

Conventional remediation methods, including filtration, coagulation–flocculation, flotation, and advanced oxidation processes, are largely ineffective for complete removal or mineralization of MPs, especially nanoscale fragments. These methods suffer from high energy demand, limited selectivity, and the generation of secondary waste streams, which restrict their scalability and environmental applicability (Zhang et al., 2025a). Accordingly, scientific attention has shifted toward sustainable, efficient, and biologically integrated remediation technologies that can achieve polymer depolymerization under environmentally relevant conditions.

Bioremediation, which harnesses the metabolic potential of microorganisms and their enzymatic machinery, offers an eco-compatible pathway for the conversion of synthetic polymers into benign end products such as CO₂, H₂O, and biomass. Several bacterial and fungal taxa, including Pseudomonas, Bacillus, Ideonella, and Aspergillus, are known to secrete esterases, cutinases, and laccases that initiate oxidative or hydrolytic cleavage of polymer chains (Shah et al., 2021). However, the inherent hydrophobicity, high crystallinity, and complex chemical structure of polymers significantly limit enzymatic access and degradation rates. Furthermore, variations in temperature, pH, salinity, and nutrient availability influence microbial metabolism and enzymatic activity, resulting in inconsistent degradation efficiencies. To address these limitations, recent studies have applied metabolic engineering, enzyme immobilization, and adaptive microbial consortia to enhance catalytic stability and broaden substrate specificity (Auta et al., 2018; Pourebrahimi and Pirooz, 2023).

In parallel, nanotechnology has emerged as a powerful and versatile approach for microplastic remediation. Nanoparticles (NPs) exhibit unique physicochemical properties, including a high surface-to-volume ratio, tunable surface reactivity, and strong catalytic potential that enable adsorption, oxidation, and degradation of polymeric pollutants (Zhang et al., 2025b). Magnetic nanoparticles such as Fe₃O₄ and γ-Fe₂O₃ demonstrate strong electrostatic and hydrophobic interactions with MPs and can be efficiently recovered using external magnetic fields, achieving removal efficiencies exceeding 90% (Enyoh et al., 2025). Photocatalytic metal oxides such as TiO₂ and ZnO produce reactive oxygen species (ROS) under ultraviolet or visible light irradiation, initiating oxidative chain scission and polymer mineralization. In addition, green-synthesized or biogenic nanoparticles produced via plant or microbial routes have gained prominence due to their reduced toxicity and high environmental compatibility (Yeszhan et al., 2025).

The integration of nanotechnology with biological systems has further advanced the field through the development of the nano–bio interface, where nanoparticles act as functional scaffolds for enzyme or microbial immobilization. These hybrid systems enhance enzymatic stability, catalytic turnover, and substrate accessibility, leading to accelerated polymer degradation. Catalytic nanostructures, often referred to as nanozymes, mimic natural enzymatic activity by generating radicals that synergistically accelerate polymer oxidation and depolymerization (Tang et al., 2022). Such nano–bio hybrid platforms often outperform either nanomaterial-based or purely biological systems, achieving greater degradation efficiencies under mild environmental conditions.

Despite their potential, several critical challenges hinder the large-scale implementation of nanomaterial-assisted bioremediation. Aggregation, surface fouling, and interference by natural organic matter reduce nanoparticle efficacy, while uncertainties regarding their environmental fate and ecotoxicological impacts persist (Enyoh et al., 2025). Current research trends, therefore, emphasize the design of biodegradable, biocompatible, and recyclable nanomaterials synthesized via green routes, capable of maintaining catalytic efficiency while minimizing ecological risk).

This review focuses on peer-reviewed literature published primarily between 2015 and 2025, with emphasis on studies addressing nano-enabled and bio-assisted remediation of microplastics and nanoplastics. Articles were selected based on their relevance to nanoparticle-assisted degradation mechanisms, microbial and enzymatic pathways, green synthesis approaches, and environmental applicability. Foundational earlier studies were included where necessary to provide mechanistic or historical context.

The literature survey was conducted using major scientific databases, including Web of Science, Scopus, PubMed, and Google Scholar. Keywords and Boolean combinations included “microplastics”, “nanoplastics”, “nanoparticles”, “nano-bioremediation”, “photocatalytic degradation”, “green synthesis”, and “microbial plastic degradation”. Reference lists of key articles were also screened to identify additional relevant studies.

This review is organized into seven main sections. Section 1 introduces the global challenge of microplastic pollution and the rationale for nano-enabled bioremediation approaches. Section 2 discusses the sources, environmental persistence, and ecological and human health impacts of microplastics. Section 3 examines the role of engineered nanoparticles in microplastic bioremediation, with emphasis on magnetic, photocatalytic, and hybrid nanomaterials. Section 4 focuses on green-synthesized bionanoparticles, highlighting sustainable production routes and their effectiveness in microplastic degradation. Section 5 explores microbial-assisted bioremediation enhanced by nanoparticles, detailing enzyme-based pathways and nano–bio hybrid systems. Section 6 addresses key challenges related to implementation, environmental stability, scalability, and regulatory considerations of nanoparticle-assisted bioremediation. Finally, Section 7 summarizes the main findings and outlines future perspectives for advancing nano-bioremediation toward safe and large-scale environmental applications.

2. Microplastic pollution: sources, persistence, and impact

Microplastics originate from both primary and secondary sources, each contributing substantially to their accumulation in terrestrial and aquatic environments. Primary microplastics are intentionally manufactured at microscopic sizes for industrial and commercial applications, while secondary microplastics arise from the fragmentation and weathering of larger plastic materials.

Industrial processes such as cutting, grinding, and thermal extrusion generate microplastic particles as by-products of surface abrasion and polymer degradation (Enfrin et al., 2019). Solvent exposure and thermal stress accelerate the breakdown of polymer chains, and untreated industrial effluents frequently discharge significant quantities of these particles, positioning industrial wastewater as a major source of environmental contamination (Prata et al., 2020).

Pre-production plastic pellets, or nurdles, serve as raw materials for plastic manufacturing and represent another dominant source of microplastics. These granules are produced by extrusion and cutting of molten polymers, and accidental spillage during production, handling, and transport allows their widespread dissemination into terrestrial and aquatic ecosystems, where their durability and resistance to degradation ensure long-term persistence (Duis and Coors, 2016; Karlsson et al., 2018).

Polymer-based paints and coatings also contribute notably to microplastic pollution. Environmental weathering processes,ses including ultraviolet radiation, precipitation, and wind ero,sion induce gradual polymer bond cleavage, leading to the formation of fine paint fragments (Song et al., 2020). Maintenance activities such as sanding and blasting further release microplastic particles enriched with pigments and heavy metals, which accumulate in soils and water bodies and persist due to their chemical stability (Turner, 2021).

Microplastics are now recognized as pervasive contaminants across aquatic and terrestrial ecosystems, challenging the efficacy of conventional wastewater treatment infrastructure. Although treatment plants serve as major filtration barriers, complete removal is not achievable due to particle heterogeneity in size, morphology, and polymer composition (Iyare et al., 2020). While modern facilities may reach removal efficiencies approaching 98%, retained microplastics often re-enter the environment through sludge reuse in agriculture, thereby contaminating soil and groundwater (Rasmussen et al., 2021). Limitations such as aging infrastructure, financial constraints, and the absence of standardized monitoring protocols further hinder the widespread application of advanced filtration and membrane technologies. The persistence and slow degradation of microplastics complicate risk assessment, underscoring the urgent need for improved removal strategies and global regulatory frameworks.

Microplastics (MPs) and nanoplastics (NPs) exert broad ecological and health effects due to their ubiquity, persistence, and ability to interact with biotic systems. Environmentally, they induce oxidative stress, reproductive toxicity, and behavioral alterations in aquatic organisms, while acting as vectors for persistent organic pollutants and heavy metals (Miller et al., 2025). Their accumulation within trophic networks disrupts food web dynamics and reduces biodiversity, with cascading consequences for ecosystem stability and productivity. Elevated concentrations have been correlated with declines in primary productivity, altering carbon and nutrient cycling and compromising biogeochemical balance (Zhu et al., 2025). Moreover, the hydrophobic surfaces of microplastics provide favorable sites for microbial colonization and pathogen transport across ecosystems.

Human exposure occurs primarily through ingestion, inhalation, and dermal contact, with microplastics detected in blood, lung tissue, placenta, and even brain tissue, indicating their capacity to traverse biological barriers (Nihart et al., 2025; WHO, 2019). Mechanistic evidence links microplastic exposure to oxidative stress, chronic inflammation, immune modulation, and metabolic dysfunctions, with heightened vulnerability observed among children and individuals with pre-existing health conditions. Despite the growing recognition of these risks, knowledge gaps remain concerning exposure thresholds, dose–response relationships, and long-term health outcomes. Addressing these uncertainties requires the development of sensitive analytical methodologies, harmonized global monitoring standards, and long-term epidemiological investigations to fully elucidate the environmental and human health implications of microplastic pollution.

3. Nanoparticles for microplastic bioremediation

3.1. Magnetic nanoparticles for microplastic capture

Nanotechnology has emerged as a transformative approach for addressing microplastic (MP) pollution by providing advanced physicochemical tools capable of capturing, degrading, and mineralizing persistent polymeric contaminants. Engineered nanoparticles possess exceptional surface-to-volume ratios, tunable surface reactivity, and high catalytic efficiency, rendering them ideal for both adsorptive and oxidative removal of plastics from complex environmental matrices. Among various classes, magnetic nanoparticles (MNPs) and semiconductor metal oxide nanostructures have demonstrated the most promising potential for scalable, efficient, and sustainable remediation.

Magnetic nanoparticles offer an innovative and energy-efficient mechanism for separating micro- and nanoplastics from aqueous environments. Their superparamagnetic behavior, large specific surface area, and customizable surface chemistry facilitate the selective adsorption and aggregation of polymeric debris (Lourens et al., 2023). Functionalization with metal ions, organic ligands, or polymeric coatings enhances affinity toward diverse plastic surfaces through electrostatic, π–π, or hydrophobic interactions (Vohl et al., 2024). Once bound, MNP–microplastic aggregates can be readily separated under an external magnetic field, providing a rapid and low-energy alternative to traditional filtration or sedimentation. Despite remaining challenges related to long-term stability, recovery efficiency, and ecotoxicological safety, recent developments in biocompatible coatings and chelating ligands have markedly improved particle selectivity and reusability, positioning MNPs as integral components of next-generation nano-enabled treatment platforms.

3.2. Photocatalytic metal oxide nanoparticles

Semiconductor metal oxide nanoparticles, particularly those exhibiting photocatalytic properties, have shown remarkable potential in degrading microplastics via reactive oxygen species (ROS) generation under light irradiation. ROS species—including hydroxyl radicals, singlet oxygen, and superoxide anions attack polymer chains, inducing oxidative cleavage, depolymerization, and eventual mineralization into CO₂ and H₂O. Titanium dioxide (TiO₂) remains the benchmark photocatalyst due to its high oxidative potential, photochemical stability, affordability, and environmental compatibility (Rex and Mukherjee, 2022). Nevertheless, its wide band gap (~3.2 eV in the anatase phase) limits activity to ultraviolet (UV) light (Bratovčić, 2024). To enhance solar utilization, numerous strategies such as nonmetal or metal ion doping, dye sensitization, and polymer hybridization have been developed to extend photoresponse into the visible spectrum (Kumar, 2023). TiO₂-based nanocomposites have achieved up to 98% mineralization of polystyrene microspheres within 12 h of UV irradiation, while C,N co-doping improved visible-light degradation of polyethylene by approximately 70% (Ariza-Tarazona et al., 2020). Incorporation with conductive polymers such as polyaniline (PANI) effectively reduces charge recombination, facilitating electron–hole separation and enhancing oxidation kinetics during prolonged irradiation (Sathinilayam et al., 2021).

Zinc oxide (ZnO), another extensively investigated semiconductor, possesses a comparable band gap (~3.2 eV), high oxidative power, and intrinsic nontoxicity. However, its photocatalytic efficiency is constrained by rapid electron–hole recombination. Hybrid architectures such as ZnO/polyvinylpyrrolidone (ZnO–PVP) nanocomposites mitigate these drawbacks by stabilizing nanoparticle dispersion, preventing agglomeration, and extending light absorption into the visible range, enabling efficient degradation of polyethylene and polystyrene under simulated solar light (Kim et al., 2024). Further enhancements have been achieved through coupling with heterovalent semiconductors such as cadmium sulfide (CdS) and graphitic carbon nitride (g-C₃N₄), or with carbon-based materials such as graphitic carbon dots and nanoclays, which promote interfacial charge transfer and augment reactive oxygen species (ROS) production, accelerating degradation kinetics and reducing secondary pollution (Bratovčić, 2024).

Iron oxide nanostructures (Fe₂O₃ and Fe₃O₄) provide complementary advantages due to their visible-light response and intrinsic magnetic recoverability. Hematite (α-Fe₂O₃), with a narrower band gap of approximately 2.1 electron volts exhibits moderate photocatalytic activity, which can be enhanced via heterojunction formation with which can be enhanced through heterojunction formation with graphitic carbon nitride g-C₃N₄ or titanium dioxide TiO₂. These Z-scheme systems improve charge separation, prolong carrier lifetime, and facilitate efficient photodegradation of polystyrene microplastics, achieving measurable mass loss under short irradiation durations (Edirisooriya et al., 2025). Magnetite (Fe₃O₄) enables simultaneous degradation and facile magnetic recovery while serving as a charge mediator in hybrid composites to enhance electron mobility and suppress recombination losses (Chai et al., 2023b; Yadav et al., 2025). Emerging technologies, such as molybdenum disulfide–iron(III) MoS₂–Fe₂O₃ oxide micromotors, utilize self-propulsion and photothermal effects to physically collide with and fragment microplastics, introducing a novel dimension to active nanoscale remediation (Edirisooriya et al., 2025).

3.3. Plasmonic and hybrid nanostructures

Cerium oxide (CeO₂) offers distinct advantages owing to its reversible Ce³⁺/Ce⁴⁺ redox cycling, which sustains continuous ROS production under illumination. Doped and heterostructured CeO₂ systems exhibit enhanced visible-light activity; cobalt-doped CeO₂ nanorods coupled with peroxymonosulfate (PMS) achieved 91.6% degradation of polyethylene terephthalate (PET) under visible light in the presence of hydrogen peroxide (Edirisooriya et al., 2025, Wan et al., 2024). Other redox-active oxides, including nickel(II) oxide, copper(I) oxide, and copper(II) oxide, and Bi-based oxyhalides, have shown promising photocatalytic performance when modified through heterojunction engineering, alkali metal doping, or plasmonic enhancement (Kumar, 2023; Bratovčić, 2024). Plasmonic titanium dioxide–gold nanocomposite (TiO₂–Au) hybrids and fluorine-anchored TiO₂ composites have achieved near-complete polymer bond cleavage under solar-simulated conditions with minimal energy input.

Collectively, these advances underscore the pivotal role of engineered nanomaterials in realizing sustainable, high-efficiency microplastic remediation. By leveraging synergistic mechanisms such as interfacial charge transfer, dopant–semiconductor coupling, and optimized light-harvesting, nanoparticle-based systems can generate elevated ROS fluxes, accelerate polymer oxidation, and achieve near-complete mineralization of persistent plastics. The integration of these photocatalytic and magnetic nanomaterials into scalable treatment frameworks represents a critical step toward closing the technological gap in global microplastic mitigation and establishing nanotechnology as a cornerstone of next-generation environmental remediation strategies (Table 1).

Table 1
Engineered nanoparticles for sustainable microplastic remediation: mechanisms, efficiency, and environmental application.

Nanoparticle Type	Mechanism of Action	Target Polymers / Microplastics	Experimental Conditions	Degradation / Removal Efficiency	Advantages	Limitations	References
Magnetic Iron Oxide Nanoparticles (Magnetite and Maghemite)	Adsorption and magnetic separation; functionalized surfaces enhance polymer binding	Polystyrene, Polyethylene, mixed microplastics	Aqueous suspensions; external magnetic field	Up to 90–95% removal of micro/nanoplastics	Rapid separation, low energy, reusable, scalable	Potential aggregation, ecotoxicity, stability in complex matrices	Lourens et al. (2023), Vohl et al. (2024)
Titanium Dioxide Nanoparticles (Anatase Phase)	Photocatalytic reactive oxygen species generation under ultraviolet or visible light; oxidative polymer cleavage	Polystyrene, Polyethylene, Polyethylene Terephthalate	Ultraviolet irradiation (254 nm), visible light with doping; aqueous or composite films	98% polystyrene mineralization in 12 hours (ultraviolet); 70% polyethylene under visible light (carbon, nitrogen co-doping)	High oxidative potential, photochemically stable, cost-effective	Ultraviolet-only activity in undoped form, limited visible-light efficiency	Nabi et al. (2020), Ariza-Tarazona et al. (2020), Sathinilayam et al. (2021)
Zinc Oxide Nanoparticles	Photocatalytic reactive oxygen species generation; enhanced electron–hole separation through composites	Polyethylene, Polystyrene	Solar-simulated light; hybrid with Polyvinylpyrrolidone, Cadmium Sulfide, or Graphitic Carbon Nitride	~60–80% polyethylene/polystyrene degradation in 200 hours	Abundant, low toxicity, tunable visible-light activity	Rapid electron-hole recombination; aggregation issues	Lam et al. (2022), Bratovčić (2024)
Iron(III) Oxide Nanoparticles (Hematite)	Photocatalytic reactive oxygen species; Z-scheme heterojunctions for enhanced charge separation	Polystyrene	Ultraviolet-visible light; heterojunction with Graphitic Carbon Nitride or Titanium Dioxide	7–10% mass reduction in 6 hours	Visible-light active, low cost, photochemically stable	Moderate photocatalytic activity alone; requires hybridization	Chai et al. (2023b)
Magnetic Iron Oxide Nanoparticles (Magnetite)	Magnetic recovery and photocatalytic electron mediator	Polystyrene, Polyethylene	Ultraviolet-visible light; hybrid composites (Titanium Dioxide, nanocellulose)	Significant mass reduction and rapid recovery	Magnetic separation; enhances electron mobility; hybrid flexibility	Particle aggregation; environmental stability	Chai et al. (2023b), Yadav et al. (2025)
Molybdenum Disulfide–Iron Oxide Micromotors	Photophoretic propulsion combined with photo-thermal degradation	Microplastics	Simulated sunlight; aqueous suspension	Targeted fragmentation and degradation	Active targeting; localized reactions; hybrid mechanism	Complex fabrication; scalability; cost	Chai et al. (2023a)
Cerium Oxide Nanoparticles (Doped or Heterostructured)	Reactive oxygen species generation via Cerium(III)/Cerium(IV) redox cycling	Polyethylene Terephthalate, Polyethylene	Visible light; peroxymonosulfate or hydrogen peroxide-assisted	91.6% polyethylene terephthalate degradation in 6 hours (cobalt-doped with peroxymonosulfate)	Redox cycling; visible-light activity; photochemically stable	High synthesis complexity; limited natural sunlight efficiency	Wan et al. (2023, 2024)
Other Redox-Active Metal Oxides (Nickel Oxide, Cuprous Oxide, Cupric Oxide, Bismuth-Based Oxyhalides)	Photocatalytic reactive oxygen species generation; heterojunction, doping, plasmonic enhancement	Polyethylene, Low-Density Polyethylene, Polystyrene	Ultraviolet-visible or solar simulation; heterojunctions or plasmonic composites	50–95% polymer degradation (dependent on system)	Bandgap tuning; improved charge separation; tailored activity	Synthesis complexity; potential metal leaching	Kumar (2023), Bratovčić (2024)
Plasmonic Hybrids (Gold-Doped Titanium Dioxide, Fluorine-Anchored Titanium Dioxide)	Enhanced visible-light absorption; plasmonic excitation; reactive oxygen species generation	Low-Density Polyethylene, Polystyrene	Simulated solar; hybrid composite films	Near-complete polymer bond cleavage under <1000 Wh simulated solar exposure	Extends light absorption to visible spectrum; accelerates reactive oxygen species production	Expensive; limited gold availability; long-term stability	Bratovčić (2024)

4. Green-synthesized bionanoparticles for sustainable microplastic degradation

Nanotechnology represents a transformative platform for the remediation of microplastic pollution, offering advanced physicochemical and catalytic tools to capture, degrade, and mineralize persistent polymeric contaminants. Nanoparticles exhibit exceptional surface-to-volume ratios, tunable surface reactivity, and high catalytic efficiency, making them ideal candidates for adsorptive, photocatalytic, and oxidative removal of plastics from environmental matrices (Ameta et al., 2018; Sur and Sathiavelu, 2022).

Green synthesis of nanoparticles provides a sustainable, eco-friendly, and cost-effective alternative to conventional methods, which often rely on hazardous reducing agents and energy-intensive processes, limiting their applicability for large-scale environmental remediation (Kirubakaran et al., 2026). Biological system,s including plants, microorganisms (bacteria, fungi, yeast, actinomycetes, and microalgae), and biopolymer,s serve as natural reducing and stabilizing agents, facilitating the formation of stable nanoparticles. Plant extracts, particularly from leaves, contain diverse phytochemicals such as terpenoids, flavones, sugars, aldehydes, ketones, amides, and carboxylic acids that mediate metal ion reduction (Singh et al., 2018). Microbial routes primarily rely on NADH-dependent reductase enzymes to catalyze the bioreduction of metal precursors (Ovais et al., 2018). Plants are often preferred due to simplicity, scalability, and low maintenance, yielding nanoparticles with smaller particle sizes, higher surface-to-volume ratios, and enhanced catalytic activity (Shankar et al., 2004; Manganyi et al., 2024).

Recent studies demonstrate the effectiveness of green-synthesized nanoparticles for microplastic removal. Iron nanoparticles synthesized from Punica granatum (pomegranate) peel extract achieved 95.48% removal of polyvinyl chloride (PVC) microplastics via photodegradation within 30 days (Al-Munayzil et al., 2025). Zinc oxide nanoparticles derived from Piper longum leaf extract exhibited rapid degradation of dental microplastics within two hours (50–90 nm) (Vas et al., 2024). Magnetic nanoparticles produced using black tea (Camellia sinensis) extract removed 95% of polyethylene (PE) microplastics through adsorption and magnetic separation within one hour (Abbasi et al., 2024). Iron(III) oxide nanoparticles from Momordica charantia fruit extract achieved 89.43% removal of polyamide (PA) microplastics in just 30 minutes (4). These findings highlight the potential of bio-synthesized nanoparticles as powerful tools for sustainable microplastic remediation, with additional applications proposed by Vas et al. (2024) to incorporate Piper longum-derived ZnO nanoparticles into mouthwashes and food hygiene products for dental microplastic degradation.

Hybrid approaches combining green synthesis with conventional methods further enhance efficacy. Russo et al. (2024) integrated humic substances derived from agri-food biomass with titanium dioxide and zinc oxide nanoparticles, forming composites that exhibited superior photodegradation of polylactic acid (PLA) microplastics by increasing reactive oxygen species (ROS) generation. Nanocellulose, particularly cellulose nanocrystals synthesized using cellulase enzymes, has also been explored for microplastic removal, although challenges remain due to irreversible cellulase binding to lignin in lignocellulosic biomass (Berlin et al., 2006). Bacterial cellulose nanofibers, although not nanoparticles, demonstrated impressive removal efficiencies of 93–96% (Faria et al., 2022).

Nanoparticles enhance conventional photocatalysis by increasing reactive surface area, stabilizing enzymes, and acting as standalone catalysts. Their size, shape, and surface charge can be engineered to optimize optical and electronic properties, enabling targeted and efficient degradation pathways under specific environmental conditions such as pH, temperature, and ionic strength (r Noble metal nanoparticles, particularly gold and silver, exhibit exceptional photocatalytic activity; for instance, gold nanoparticles supported on titanium dioxide can harvest visible light to drive oxidative degradation of microplastic contaminants (Sur and Sathiavelu, 2022) (Table 2).

Table 2
Representative studies on green-synthesized bionanoparticles for microplastic removal.

Nanoparticle Type (Particle Size)	Biological Source	Green Synthesis Route	Target Microplastic	Mechanism of Removal	Reaction Conditions (Light, pH, Temperature)	Removal/Degradation Efficiency	Reference
Iron nanoparticles (20–50 nm)	Punica granatum (pomegranate) peel extract	Plant	Polyvinyl chloride (PVC)	Photodegradation	UV light, pH 7, 25°C	95.48% in 30 days	Al-Munayzil et al. (2025)
Zinc oxide nanoparticles (50–90 nm)	Piper longum leaf extract	Plant	Dental microplastics	Photocatalytic degradation	Simulated solar light, pH 6–7, 28°C	Effective within 2 hours	Vas et al. (2024)
Magnetic nanoparticles (40–70 nm)	Camellia sinensis (black tea) extract	Plant	Polyethylene (PE)	Adsorption and magnetic separation	Ambient light, pH 7, 25°C	95% in 1 hour	Abbasi et al. (2024)
Iron(III) oxide nanoparticles (30–60 nm)	Momordica charantia fruit extract	Plant	Polyamide (PA)	Surface adsorption and magnetic separation	Ambient light, pH 6–7, 25°C	89.43% in 30 minutes	Narwal et al. (2025)
Silver nanoparticles (10–50 nm)	Azadirachta indica (neem) leaf extract	Plant	Polystyrene (PS)	Oxidative degradation	Visible light, pH 7, 30°C	82% in 24 hours	Kumari et al. (2022)
Gold nanoparticles (10–32 nm)	Cymbopogon citratus (lemongrass) leaf extract	Plant	Polyethylene terephthalate (PET)	Photocatalytic degradation	Visible light, pH 7, 28°C	78% in 12 hours	Pathania et al. (2022)
Copper oxide nanoparticles (20–60 nm)	Trigonella foenum-graecum (fenugreek) seed extract	Plant	Polypropylene (PP)	Photodegradation and reactive oxygen species generation	Simulated solar light, pH 7, 30°C	85% in 48 hours	Lakshmanan et al. (2025)
Titanium dioxide nanoparticles (25–87 nm)	Azadirachta indica (neem) leaf extract	Plant	Polystyrene (PS)	Photocatalytic degradation under UV/visible light	UV/visible light, pH 6–7, 25–30°C	90% in 36 hours	Thakur et al. (2019)
Cerium oxide nanoparticles (20–65 nm)	Moringa oleifera leaf extract	Plant	Polyethylene terephthalate (PET)	ROS-mediated photocatalytic degradation	Visible light, pH 7, 28°C	91% in 24 hours	Singh and Bhardwaj (2024)
Magnetite nanoparticles (Fe3O4) (30–70 nm)	Camellia sinensis (green tea) extract	Plant	Polyethylene (PE)	Adsorption and magnetic separation	Ambient light, pH 7, 25°C	93% in 1 hour	Ishak et al. (2019)
Bimetallic Ag-Fe nanoparticles (20–60 nm)	Punica granatum peel + microbial consortium	Plant + Microbe	Polystyrene (PS)	Combined oxidative and adsorption mechanisms	Visible light, pH 7, 28°C	88% in 24 hours	Sharma et al. (2025)
Zinc oxide-graphitic carbon dots (ZnO–gCDs) (30–80 nm)	Piper nigrum seed extract	Plant	Polypropylene (PP)	Photocatalytic degradation under visible light	Simulated solar light, pH 7, 30°C	87% in 36 hours	Lam et al. (2022)

Collectively, these advances demonstrate that nanoparticle engineeri,ng including green synthesis, hybrid composites, and photocatalyst optimization ffers a versatile and environmentally sustainable strategy for microplastic remediation. By leveraging synergistic effects of reactive surfaces, dopants, interfacial charge transfer, and biologically derived stabilizers, these systems hold significant potential for large-scale, next-generation environmental applications.

5. Microbial-assisted bioremediation enhanced by nanoparticles

The interaction between nanoparticles and microbial enzymes is central to both natural ecosystems and engineered biocatalytic systems. In soils, nanoparticles can directly modulate microbial enzymatic activity, influencing nutrient cycling and organic matter transformation. For instance, Fe- and Zn-citrate nanoparticles have been shown to stimulate or inhibit specific enzymatic pathways and reshape microbial community dynamics (Awasthi et al., 2025). Consequently, nanoparticles act as both enhancers and potential stressors in situ.

In engineered systems, enzyme–nanoparticle conjugates increase catalytic stability, activity, and operational longevity. Immobilization of microbial enzymes on biofunctionalized nanocomposites improves turnover and robustness; for example, L-asparaginase immobilized on magnetic graphene-oxide nanocomposites maintained activity across multiple cycles due to improved structural stability and facile magnetic recovery (Monajati et al., 2024), while iron-oxide nanoassemblies exhibit enhanced resistance to denaturation and allow magnetic recyclability (Valls-Chivas et al., 2023). The synergy between nanoparticles and microbial systems further amplifies polymer degradation by enhancing enzyme stability, increasing local substrate concentration, and enabling reusability. Photocatalytic nanoparticles generate reactive oxygen species (ROS) that pre-oxidize polymers, lowering activation barriers for hydrolytic and oxidative enzymes, while surface-engineered carriers improve enzyme–substrate interactions on microplastic surfaces under environmentally relevant conditions, collectively enhancing reaction kinetics and mass transfer. These findings highlight nanoparticles as both regulators of microbial enzymatic function and platforms for enzyme stabilization, advancing biocatalysis, environmental remediation, and industrial biotechnology.

5.1. Enzyme-based degradation pathways

Microorganisms, including bacteria and fungi, play a pivotal role in the biodegradation of major synthetic polymers, each employing distinct enzymatic pathways tailored to polymer chemistry. Polyethylene terephthalate (PET), a polyester of aromatic esters, is depolymerized by microbial hydrolases such as PETase from Ideonella sakaiensis, which hydrolyzes PET into mono-(2-hydroxyethyl) terephthalate (MHET) and terephthalic acid, while MHETase converts MHET into terephthalate and ethylene glycol (Sefidi Heris, 2024). Other PET degraders include Pseudomonas nitroreducens, P. monteilii, and cutinase-producing actinomycetes (Figure 1) (Cai et al., 2023).

Figure 1
PET depolymerization using engineered PETase immobilized on green-synthesized silica nanoparticles. Illustration adapted from Cai et al. (2023).

Polyethylene (PE) is highly recalcitrant, but bacteria such as Rhodococcus, Pseudomonas, Bacillus, and Arthrobacter secrete oxidative enzymes (e.g., laccases, alkane hydroxylases) that introduce carbonyl groups and reduce molecular weight, while ligninolytic white-rot fungi contribute via peroxidases (Ru, Huo & Yang, 2020). Polystyrene (PS) degradation remains challenging; select bacterial strains (Rhodococcus ruber, Xanthomonas, Bacillus) and insect-gut symbionts can partially depolymerize PS to oligomers over weeks, often relying on monooxygenase and styrene-oxide isomerase pathways (Sefidi Heris, 2024). Polyurethane (PU), particularly polyester-based forms, is susceptible to ester hydrolysis by microbial lipases, cutinases, and serine esterases (Ru, Huo and Yang, 2020), while polyether-PU resists degradation. Poly(vinyl chloride) (PVC), with its stable C–C backbone and high chlorine content, requires oxidative depolymerization coupled with enzymatic dehalogenation; gut symbionts of Spodoptera frugiperda and fungi such as Aspergillus niger and Phanerochaete chrysosporium contribute to sequential dechlorination and polymer scission (Zhang et al., 2022; Jiang et al., 2025).

Microbial hydrolytic pathways target polymers bearing ester or urethane linkages (PET, polyester PU) via esterases, lipases, proteases, and cutinases, releasing oligomers suitable for cellular uptake. Polymers lacking hydrolysable groups (PE, PS, PVC) undergo oxidative decomposition through oxidoreductases, including laccases and peroxidases, which functionalize backbones via radical chemistry and generate more hydrophilic intermediates for further catabolism (Sefidi Heris, 2024; Ru et al., 2020). Subsequent intracellular assimilation channels these intermediates into central metabolism, such as the TCA cycle or the phenylacetic-acid superpathway, culminating in CO₂, H₂O, and biomass formation.

5.2. Nano–bio hybrid systems and enzyme immobilization

Coupling nanoparticles with microbial systems enhances these biodegradation processes through multiple synergistic mechanisms. Nanoparticles serve as immobilization platforms, increasing enzyme stability, local substrate concentration, and reusability. Photocatalytic nanoparticles generate ROS that pre-oxidize polymers, reducing activation barriers for enzymatic hydrolysis and oxidation. Surface-engineered carriers improve enzyme–substrate interactions on microplastic surfaces under environmentally relevant conditions, enhancing mass transfer and reaction kinetics. Together, these nano–bio constructs significantly shorten polymer half-lives under controlled conditions and provide modularity for scale-up in integrated water-treatment and environmental remediation workflows, while ecological safety remains a critical consideration.

Importantly, the convergence of microbial enzymology with nanoparticle engineering provides a versatile platform for tackling a wide spectrum of polymeric pollutants. By integrating enzymatic specificity, nanoparticle-mediated stabilization, and substrate-targeted delivery, these systems can address recalcitrant polymers that resist conventional biodegradation. The modular nature of nano–bio assemblies allows adaptation to diverse environmental matrices from soils and sediments to wastewater streams while enabling potential scale-up for industrial applications. This synergy lays the foundation for the subsequent case studies, which exemplify practical implementations of nanoparticle-enhanced microbial biocatalysis for plastic remediation.

6. Implementation of nanoparticle-assisted bioremediation: challenges, environmental stability, and regulatory considerations

Scaling up nanoparticle-assisted microbial bioremediation for industrial and environmental applications faces multiple interrelated challenges. High production costs of enzymes such as polyethylene terephthalate hydrolase and cutinase, along with green-synthesized nanoparticles, limit economic feasibility. Enzyme instability under fluctuating pH, temperature, or shear stress reduces degradation efficiency, while the structural heterogeneity of microplastics and other recalcitrant polymers complicates selective degradation and may generate secondary pollutants. Hydrophobic polymers, including polyurethane, require energy-intensive pretreatments to enable enzymatic access, further increasing operational demands. Strategies to overcome these limitations include immobilizing enzymes on silica or magnetic nanoparticles to improve stability, engineering microbial strains for higher catalytic efficiency, applying subcritical hydrothermal liquefaction pretreatment to facilitate polymer breakdown, and using biofilm-enhanced reactors to optimize microbial–enzyme synergy Figure 2. Environmental stability of nanoparticles is critical, with green-synthesized nanoparticles incorporating proteins, polysaccharides, flavonoids, or phenolic compounds preventing aggregation and maintaining activity. Environmental matrices, such as extracellular polymeric substances and alginate, further stabilize nanoparticles, while nanoparticle morphology, including graphene-based or porous iron oxide structures, influences long-term functionality and catalytic performance Figure 3. Safe and sustainable implementation requires adherence to international regulatory frameworks, such as the European Union Registration, Evaluation, Authorisation and Restriction of Chemicals framework, the Organization for Economic Cooperation and Development testing guidelines, and World Health Organization recommendations. Life-cycle assessment ensures environmental compatibility, minimizes nanoparticle persistence, and prevents secondary pollution, while magnetic nanoparticle systems enable recovery and reuse. Monitoring potential interactions between nanoparticles and microplastics is also essential to avoid ecological risks, including horizontal gene transfer and disruption of beneficial microbial communities. Integrating these technological, environmental, and regulatory considerations provides a robust pathway for the scalable, safe, and effective deployment of nanoparticle-assisted bioremediation in wastewater treatment and environmental restoration.

Figure 2
Diagram illustrating the two-step process for polyurethane degradation: subcritical hydrothermal liquefaction (HTL) pretreatment followed by nano-enhanced cutinase digestion. Adapted from Gallorini et al. (2022, as cited in Dey et al., 2024).

Figure 3
Comparative analysis of degradation efficiencies and process characteristics across nano-enzymatic case studies targeting PET, microplastics, and polyurethane. Created in Canva based on Cai et al. (2023), Masiá et al. (2024), and Gallorini et al. (2022, as cited in Dey et al., 2024).

7. Conclusion and future perspectives

The pervasive infiltration of microplastics and nanoplastics across terrestrial, aquatic, and atmospheric systems represents one of the most pressing environmental crises of our era. Conventional remediation strategies remain inadequately limited by energy demand, secondary waste generation, and inability to capture nanoscale pollutants. Against this backdrop, nano-bioremediation has emerged as a transformative, next-generation solution that merges the catalytic precision of nanotechnology with the metabolic versatility of microorganisms. By creating synergistic nano–bio interfaces, this approach enables the adsorption, oxidation, and enzymatic depolymerization of persistent polymers into environmentally benign end products.

Despite remarkable laboratory success—achieving up to 90–98% degradation efficiencies—translating nano-bioremediation into scalable and field-ready systems faces several formidable challenges. These include high production costs of both enzymes and nanoparticles, limited enzyme stability under fluctuating environmental conditions, heterogeneity of polymer matrices, and the tendency of nanoparticles to aggregate or lose activity in complex natural systems. Moreover, uncertainties surrounding the environmental fate and ecotoxicological risks of nanomaterials necessitate rigorous assessment and governance before widespread implementation.

Emerging technological innovations are now converging to overcome these barriers. Green-synthesized and biodegradable nanomaterials, derived from plant or microbial sources, minimize toxicity while enhancing catalytic activity and stability. Genetically engineered and immobilized enzymes extend operational lifetimes, while biofilm-based reactors and hybrid photocatalytic–biological systems enable continuous operation and regeneration. Coupled pretreatment processes such as subcritical hydrothermal liquefaction improve polymer accessibility, further accelerating degradation kinetics. Together, these advancements establish a foundation for efficient, safe, and circular nano-bioremediation technologies.

Looking forward, the future of nano-bioremediation lies in integration, innovation, and interdisciplinary cooperation.

• Integration will link biocatalysis, nanomaterial design, and reactor engineering into unified treatment platforms capable of continuous operation under real-world conditions.

• Innovation will emerge from data-driven nanodesign, where artificial intelligence and molecular modeling predict optimal nano–enzyme architectures and degradation pathways.

• Interdisciplinary cooperation—uniting materials scientists, microbiologists, engineers, and policymakers—will ensure that innovation aligns with environmental ethics and global sustainability goals.

Establishing harmonized regulatory frameworks and incorporating life-cycle assessment will be essential to validate safety, ensure recyclability, and prevent secondary pollution. The incorporation of nano-bioremediation into a circular bioeconomy—where degradation byproducts are valorized into fuels, monomers, or biomaterials—will transform plastic waste from a pollutant into a renewable resource.

In essence, nano-bioremediation stands not merely as a technological advancement but as a paradigm shift toward sustainable environmental restoration. By bridging molecular innovation with ecological stewardship, it offers a tangible pathway to restore planetary health and secure a cleaner, low-carbon future.

Data Availability Statement

The data supporting the findings of this study are available within the article. Additional information is available from the corresponding author upon reasonable request.

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Edited by

• Editor:
  Takako Matsumura Tundisi

Publication Dates

• Publication in this collection
  10 Apr 2026
• Date of issue
  2026

History

• Received
  27 Oct 2025
• Accepted
  26 Jan 2026