Pharmaceutical Chemistry Institute of Pharmacy and Research, Badnera
Silver nanoparticles (AgNPs) have gained considerable attention as advanced nanocarriers in pharmaceutical drug delivery due to their distinctive physicochemical properties, surface reactivity, and therapeutic potential. In recent years, biofabrication approaches employing natural polymers have emerged as sustainable and eco-friendly alternatives to conventional chemical synthesis methods, offering enhanced biocompatibility, reduced toxicity, and improved biological performance. Although widely investigated polymers such as chitosan and alginate have dominated research in this domain, several natural polysaccharides and biopolymers remain largely unexplored for non-steroidal anti-inflammatory drug (NSAID) delivery systems. Natural polymers including arabinogalactan, gum kondagogu, pullulan, tragacanth, and galactomannans possess unique structural, physicochemical, and biological characteristics that make them promising candidates for the biofabrication of silver nanoparticles.The incorporation of NSAIDs into silver nanoparticle systems using these under-explored natural polymers may improve drug stability, enhance controlled and sustained release, and increase therapeutic efficacy while potentially reducing gastrointestinal and systemic adverse effects associated with conventional NSAID therapy. This review systematically highlights recent advances in biofabrication strategies for natural polymer-based silver nanoparticles, with emphasis on formulation approaches, drug loading mechanisms, and characterization techniques. Furthermore, in-vitro and in-vivo evaluation parameters relevant to anti-inflammatory drug delivery are discussed. The review also addresses key challenges related to safety, scalability, and regulatory translation, while identifying critical research gaps and future opportunities for the development of novel NSAID-loaded silver nanoparticle systems using lesser-studied natural polymers
The advent of nanotechnology has significantly transformed drug delivery, enabling improved therapeutic efficacy, controlled release, and targeted action of pharmaceutical agents. Among metallic nanoparticles, silver nanoparticles (AgNPs) have attracted considerable attention due to their unique physicochemical properties, including large surface-to-volume ratio, tunable optical features, and intrinsic antimicrobial activity. AgNPs have been widely studied for biomedical applications such as wound healing, coatings, diagnostics, and as carriers in drug formulations. Traditional chemical and physical synthesis methods often involve hazardous reagents and energy-intensive processes, limiting clinical translation. In contrast, biofabrication the use of biological systems or natural polymers as reducing, stabilizing, and capping agents offers a sustainable, biocompatible alternative. Natural polymers derived from plants, microbes or animal sources not only facilitate green synthesis of AgNPs but also provide functional groups for effective drug loading and controlled release. Examples include polysaccharides like arabinogalactan, alginate, chitosan, pectin, pullulan, and gums such as tragacanth and xanthan. Despite extensive research on AgNPs and polymer-nanocomposite systems for antimicrobial and tissue engineering applications, the integration of natural polymer-mediated biofabricated AgNPs with NSAIDs such as ketorolac tromethamine remains under-reported. Ketorolac tromethamine is a potent non-steroidal anti-inflammatory drug (NSAID) commonly used for pain management, but suffers from challenges including gastrointestinal irritation and rapid elimination. Incorporating ketorolac into biofabricated polymer-AgNP systems could enhance its therapeutic index by improving solubility, prolonging release, and reducing side effects. However, many natural polymers suitable for AgNP biofabrication have not yet been systematically evaluated for such NSAID delivery applications.[1]
Inflammatory disorders represent a major therapeutic challenge worldwide, with non-steroidal anti-inflammatory drugs (NSAIDs) being the most commonly prescribed agents for the management of pain and inflammation. Despite their clinical effectiveness, NSAIDs are often associated with gastrointestinal irritation, renal toxicity, and systemic side effects, especially upon prolonged use. These limitations have encouraged the development of novel drug delivery systems capable of improving therapeutic efficacy while reducing adverse effects.Traditional chemical synthesis of silver nanoparticles often involves toxic reducing agents and stabilizers, raising concerns regarding biocompatibility and environmental safety. To address these concerns, biofabrication or green synthesis approaches using natural polymers and biological materials have emerged as sustainable alternatives. Biofabricated silver nanoparticles exhibit improved safety profiles, enhanced stability, and greater suitability for pharmaceutical applications. Natural polymers play a critical role in biofabrication due to their biodegradability, non-toxicity, and functional groups capable of reducing and stabilizing metal nanoparticles. While polymers such as chitosan, alginate, and gelatin have been widely investigated, several other natural polymers remain largely unexplored for silver nanoparticle based NSAID delivery. Polysaccharides such as arabinogalactan, gum kondagogu, pullulan, tragacanth, guar gum, and galactomannans possess unique structural and physicochemical properties, including high aqueous solubility, film-forming ability, and biological compatibility, which make them promising candidates for nanoparticle synthesis and drug delivery.[2]The utilization of these underexplored natural polymers in the biofabrication of silver nanoparticles offers new opportunities for developing advanced anti-inflammatory drug delivery systems. Such systems may provide controlled drug release, enhance therapeutic performance, and reduce systemic toxicity.[9] This review aims to comprehensively evaluate biofabricated silver nanoparticles prepared using lesser-studied natural polymers, with emphasis on formulation strategies, physicochemical characterization, and their potential in NSAID delivery. Furthermore, the review identifies existing research gaps and future prospects for expanding the application of novel natural polymers in silver nanoparticle-based anti-inflammatory therapy.
Rationale for Bio fabricated Silver Nanoparticles in NSAID Delivery:
The integration of silver nanoparticles (AgNPs) into drug delivery systems represents a transformative advancement in nanomedicine, particularly for the delivery of poorly soluble or rapidly cleared therapeutic agents such as non-steroidal anti-inflammatory drugs (NSAIDs). AgNPs exhibit unique physicochemical and biological properties-such as high surface-to-volume ratio, tannable particle size, surface functionalization capacity and intrinsic bioactivity-that make them promising carriers for pharmaceutical applications. These features collectively enhance drug bioavailability, enable controlled and targeted release, and reduce systemic side effects when compared with conventional formulations.
First, the nanoscale size (typically 1-100 nm) and high surface area of AgNPs facilitate improved cellular uptake and interaction with biological membranes. This characteristic allows efficient transport of drug molecules to target sites through both passive and active mechanisms, potentially enhancing therapeutic outcomes of NSAIDs like ketorolac tromethamine, which otherwise suffer from limitations such as rapid clearance and gastrointestinal irritation in conventional formulations
Second, AgNPs can be engineered to control drug release kinetics. When drugs are adsorbed on or encapsulated within nanoparticles, the release profile can be sustained or modulated, which improves drug bioavailability and decreases dosing frequency. Previous studies on metallic drug-loaded nanocomposites, including NSAIDs such as ibuprofen and naproxen embedded within silver matrices, have shown that metals can act as sustained release reservoirs, enhancing therapeutic retention and activity.
Third, AgNPs possess intrinsic antimicrobial and anti-inflammatory properties which may synergize with NSAIDs to confer additional therapeutic benefits. The antimicrobial mechanisms of AgNPs involve disruption of microbial membranes, generation of reactive oxygen species (ROS), and interaction with cellular proteins, offering an additional functional advantage especially in conditions with secondary infections or inflammatory components.
Fourth, surface engineering and functionalization of AgNPs-especially through bio fabrication using natural polymers-can improve biocompatibility and reduce toxicity, addressing one of the primary concerns associated with metal nanoparticles. Biofabrication using natural polymers such as arabinogalactan, alginate, pectin, chitosan, pullulan, and other biopolymers provides capping, stabilization, and functional groups that enhance interactions with drug molecules and biological systems, thereby tailoring performance for NSAID delivery. These polymers introduce hydrophilic moieties and steric barriers that promote colloidal stability, reduce uncontrolled silver ion release, and facilitate controlled drug adsorption and release.
Finally, natural polymer-assisted green synthesis (biofabrication) offers an eco-friendly, cost-effective and scalable route to produce AgNPs with improved safety profiles versus conventional chemical methods. Biogenic approaches exploit plant extracts or biopolymers as reducing and capping agents, which not only circumvent toxic reagents but also inherently incorporate biocompatible coatings that are desirable for drug delivery formulations.[3]]
Selection of Natural Polymers (Under-explored Polymers for NSAIDs):
The formulation strategy for biofabricated silver nanoparticles (AgNPs) requires the careful selection of natural polymers that serve as reducing, stabilizing and drug-carrying agents. Natural polymers are increasingly preferred due to their biocompatibility, biodegradability, low toxicity, cost-effectiveness and functional versatility compared with synthetic alternatives. They can interact with silver ions and therapeutic agents to generate stable nanocomposites with improved drug loading, controlled release, and enhanced bioavailability.Many studies have explored common natural polymers such as chitosan, alginate and cellulose derivatives for nanoparticle synthesis and drug delivery. However, several promising natural polymers still remain under-explored, particularly in the context of NSAID delivery with AgNP systems.[4]
Commonly Studied Natural Polymers:
Chitosan:
Chitosan is widely used due to its biodegradability, biocompatibility and ease of chemical modification. It stabilizes nanoparticles via electrostatic interactions and facilitates drug entrapment in nanosystems.
Alginate:
Alginate, an anionic polysaccharide from brown seaweed, forms hydrogels and gels under mild conditions. It has been used in nanoparticle and hydrogel systems for drug encapsulation and controlled release.[5]
Under-explored Natural Polymers for NSAID Delivery:
Despite the more frequent use of the above polymers, several under-explored natural polymers hold significant potential for AgNP formation and NSAID delivery, but have not been systematically studied in this context.
Arabinogalactan
Arabinogalactan is a plant-derived polysaccharide with excellent water solubility, non-toxicity and functional hydroxyl groups that can interact with metal ions and drug molecules. Its use as a stabilizer in AgNP synthesis has been documented in other nanomedicine applications but remains largely unexplored for NSAID-loaded AgNPs. Its structure could potentially enhance drug solubility and controlled release.
Pectin
Pectin is a plant cell wall polysaccharide known for gel-forming ability, and has been used in microcapsules and nanoparticles for food and drug encapsulation. However, the integration of pectin in AgNP systems for NSAID delivery is still limited despite its potential to improve drug retention and sustain release.
Pullulan
Pullulan is a microbial polysaccharide with excellent film forming ability, biocompatibility and non-immunogenic nature. Few studies have synthesized AgNPs using pullulan, mainly for antimicrobial or biosensing purposes, but reports on pullulan-AgNPs carrying NSAIDs or enhancing drug release profiles remain sparse. This gap suggests an opportunity for innovation.
Gum Tragacanth and Gum Acacia
Natural gums such as gum tragacanth and gum acacia are high-molecular-weight polysaccharides with strong intestinal mucoadhesive properties. Studies have investigated their use in nanoparticle composites for sustained release of therapeutic agents, but their application in AgNP-based NSAID delivery systems has not been sufficiently explored.[6]
Rationale for Selection: The under-explored polymers listed above share several desirable properties for AgNP drug delivery systems:
Functional Groups for Reduction and Stabilization- Hydroxyl and carboxyl groups can reduce silver ions and stabilize nanoparticles.
Potential for Controlled Release- Polymers like pectin and arabinogalactan can form networks that modulate drug release kinetics.
Biocompatibility and Biodegradability- Natural origin minimizes toxicity and enhances clinical translation prospects. Therefore, selecting under-explored natural polymers such as arabinogalactan, pectin, pullulan, gum tragacanth and gum acacia for biofabricated AgNP-based NSAIDs represents a promising direction that could yield novel formulations with enhanced performance and translational potential.
Formulation Strategy for Natural Polymer-Based Silver Nanoparticles:
The formulation of natural polymer-based silver nanoparticles (AgNPs) involves a carefully designed strategy to ensure nanoparticle stability, biocompatibility, drug loading efficiency, controlled release, and targeted therapeutic action. Central to this strategy is the selection of a natural polymer that serves simultaneously as a reducing agent, stabilizer/capping agent, and drug carrier, enabling green synthesis and enhanced functional performance of the nanoparticles.
Green Biofabrication of AgNPs:
In green biofabrication, natural polymers with functional groups (e.g., hydroxyl, carboxyl, amine) reduce silver ions (Ag?) to elemental silver (Ag?), forming nanoparticles without toxic chemicals. This contrasts with conventional chemical methods that use hazardous reducing agents and require additional stabilizers. Natural polymers provide an eco-friendly, cost-effective route for AgNP synthesis while improving biocompatibility-a crucial factor for biomedical and drug delivery applications. AgNPs synthesized via green methods have demonstrated consistent size control and surface functionalization, which are pivotal for stable formulations and drug loading.
Role of Natural Polymers in AgNP Formation:
Natural polymers contribute multiple functionalities in formulation:
Reducing Activity: Polymers containing active functional groups (e.g., polysaccharides) donate electrons that reduce Ag? to Ag?.
Stabilization/Capping: After reduction, the polymer chains surround AgNPs, preventing aggregation by providing steric and electrostatic stabilization, which enhances colloidal stability and biological safety.
Drug Loading and Interaction: The polymer matrix enables physical adsorption or chemical interaction with drug molecules, improving encapsulation efficiency and enabling controlled release.[7]Thus, natural polymer-based AgNPs serve as multifunctional drug delivery platforms, combining synthesis, stabilization, and drug encapsulation in a single system.
Key Components of Formulation Strategy:
a. Silver Precursor: The starting precursor typically is silver nitrate (AgNO?), which supplies Ag? ions. The stoichiometry of Ag? influences the size, surface characteristics, and subsequent drug carrying capacity of the nanoparticles.
b. Natural Polymer Selection
Selecting an appropriate natural polymer determines the ultimate functional behavior of AgNPs:
Polysaccharides (e.g., gum, arabinogalactan, pectin): Provide multiple reducing/stabilizing functional groups and biodegradability.
Proteins (e.g., albumin, gelatin): May enable targeted interactions and higher drug affinity.
Other plant-derived polymers: Unique structural features (e.g., branching in arabinogalactan) can enhance drug loading and controlled release.[29]The polymer choice impacts particle size, surface charge, drug–polymer interactions, release kinetics, and biodegradation behaviour-all critical for effective drug delivery.
c. Drug Incorporation Strategy
Drug molecules (such as NSAIDs like ketorolac tromethamine) can be:
Incorporated during synthesis: Drugs interact with polymer chains concurrently with Ag? reduction, becoming entrapped within the growing nanoparticle matrix.
Loaded post-synthesis: Preformed AgNPs are incubated with drug solutions, allowing drug adsorption onto polymer surfaces or within polymer matrices.[22]
Both strategies have implications for drug loading efficiency, release profile, and stability. Optimization involves adjusting polymer concentration, pH, temperature, and reaction time.
d. Controlled Release Considerations
The polymer matrix surrounding AgNPs can modulate drug release via diffusion barriers and degradation kinetics. Polymers with hydrophilic and biodegradable characteristics allow sustained or stimuli-responsive drug release, reducing side effects and improving therapeutic efficacy.
Formulation Optimization Parameters:
To achieve a targeted drug delivery profile, several formulation variables are systematically optimized:
pH and temperature during synthesis affect particle nucleation and growth.
Polymer-to-metal ratio influences particle size and surface properties.
Stirring/agitation and reaction time affect nanoparticle uniformity and drug encapsulation.
Post-synthesis modifications such as cross-linking or surface functionalization can tailor release behavior or targeting ability.[8]
A stepwise schematic illustrating the synthesis of silver nanoparticles. The nanoparticle dispersion is obtained by sequential addition of sodium citrate and sodium borohydride, followed by heating for 30 minutes. The resulting mixture is centrifuged for 30 minutes to separate the particulate fraction from the supernatant. After discarding the supernatant, the collected pellet is re-dispersed in an aqueous medium to yield stabilized silver nanoparticles (SNPs).
Biofabrication Mechanisms of Silver Nanoparticles:
Biofabrication refers to the green synthesis of nanoparticles using biological agents such as plant extracts, microorganisms, enzymes, or natural polymers. Unlike conventional chemical or physical methods, biofabrication offers a rapid, eco-friendly, cost-effective and biocompatible approach to produce silver nanoparticles (AgNPs), eliminating toxic reducing agents and harsh reaction conditions.[9]
Role of Reducing Biomolecules:
Natural polymers (polysaccharides, proteins) and plant metabolites (phenolics, flavonoids, terpenoids) possess functional groups capable of reducing silver ions (Ag?) into metallic silver (Ag?). This primarily involves electron donation from hydroxyl (-OH), carbonyl (-C=O) and amine (-NH?) groups present in the biomolecules.
Polysaccharides: The abundant hydroxyl groups in polysaccharides such as arabinogalactan, pectin and pullulan donate electrons to Ag? ions, resulting in reduction and nucleation of AgNPs
Proteins & Enzymes: Certain amino acid residues (e.g., tyrosine, cysteine) can reduce Ag? due to their electron-rich side chains [10]
This reduction step initiates nucleation, where small clusters of metallic silver atoms form the base nuclei for nanoparticles.
Stabilization and Capping by Natural Polymers:
After nucleation, the growing nanoparticles require stabilization to prevent aggregation. Natural polymers act as capping agents by adsorbing onto the nanoparticle surface through electrostatic or steric interactions. This capping layer:
Prevents particle aggregation
Controls final particle size and morphology
Provides functional groups for further drug attachment or chemical modifications
Polymers such as arabinogalactan and pectin contain multiple functional groups (-OH, -COOH) that strongly interact with AgNP surfaces, leading to stable colloidal dispersions. This capping also contributes to biocompatibility and controlled drug release when used in delivery systems.
Mechanistic Pathway Summary: Biofabrication of AgNPs typically follows:
Reduction Phase: Bioactive molecules donate electrons → Ag? → Ag?
Nucleation Phase: Ag? atoms aggregate → seed nuclei formation
Growth Phase: Additional atoms join nucleated seeds → growing nanoparticles
Stabilization Phase: Natural polymers adsorb on surface → steric/electrostatic stabilization
This mechanistic sequence ensures controlled particle size, morphology, stability, and surface functionality all crucial for efficient drug loading and release. [11]
Advantages of Biofabrication Mechanisms: Compared to chemical synthesis, biofabrication:
Eliminates toxic reducing agents
Operates under mild temperatures and ambient conditions
Produces nanoparticles with biocompatible coatings
Enhances downstream drug formulation compatibility
Enables surface functionality for targeted or controlled drug delivery
These features make biofabricated AgNPs especially suitable for integration with pharmaceutical agents like NSAIDs. [12]
Drug Loading & Encapsulation Strategies for NSAIDs:
The therapeutic efficacy of nanoparticle-based drug delivery systems (NDDS) depends largely on efficient drug loading and encapsulation, which determine how much drug can be carried, how effectively it is released at the target site, and how stable the formulation remains during storage and administration. For NSAIDs such as ketorolac tromethamine, improved drug loading is critical due to their poor solubility, rapid systemic clearance, and gastrointestinal side effects in conventional formulations. [13]
Entrapment During Nanoparticle Synthesis
One common approach for drug loading in polymer-AgNP systems is simultaneous drug incorporation during nanoparticle formation. In this method, NSAID molecules are added to the reaction mixture containing the silver precursor and natural polymer (acting as reducing/stabilizing agent). As Ag? ions are reduced and nanoparticles nucleate and grow, drug molecules become entrapped within the polymer matrix or adsorbed onto the NP surface.
This strategy benefits from:
Enhanced drug–polymer interactions
Uniform distribution of drug within nanoparticle structure
Potential for sustained release due to polymer matrix diffusion barriers
For example, in polymer-stabilized silver nanocomposites, the drug becomes physically entrapped due to electrostatic interactions and hydrogen bonding between NSAID functional groups and polymer chains. [14]
Adsorption Onto Pre-Formed Nanoparticles:
A second strategy involves first synthesizing polymer-AgNPs, followed by post-synthesis drug loading. In this method, the drug solution is incubated with the nanoparticle dispersion under controlled conditions (pH, temperature, stirring), allowing NSAID molecules to adsorb onto the nanoparticle surface or within the polymeric layer that caps the AgNPs.
Advantages include:
Greater control over drug loading conditions
Ability to optimize drug amount post-synthesis
Reduced risk of destabilizing NP formation during loading
Adsorption is driven by electrostatic attraction, hydrophobic interactions, and hydrogen bonding between drug molecules (e.g., carboxylic groups of NSAIDs) and the functional groups of the natural polymer (e.g., –OH, –COOH) on the nanoparticle surface.
Polymer-Drug Conjugation
Some approaches involve chemical conjugation of NSAIDs to polymer chains prior to nanoparticle formation. Functional groups on the polymer backbone (e.g., aldehyde, carboxyl) form covalent linkages with reactive moieties on NSAID molecules. After conjugation, this drug-polymer complex is used for AgNP biofabrication, leading to nanoparticles where the drug is covalently bound and released via polymer degradation.This method provides:
Precise control of drug release kinetics
Reduced premature drug release
Potential for stimuli-responsive release (e.g., pH, enzymes)However, chemical conjugation requires careful design to preserve NSAID biological activity and polymer biodegradability. [15]
Factors Influencing Drug Loading Efficiency:
Drug loading and encapsulation efficiency (LE) depend on:
Polymer type and concentration: Hydrophilic polymers with abundant functional sites (e.g., arabinogalactan, pectin) enhance drug entrapment through hydrogen bonding and ionic interactions.
pH and ionic strength: Drug ionization state affects interaction with polymer and silver surface.
Nanoparticle surface charge (zeta potential): Optimized surface charge promotes stable drug adsorption and prevents aggregation.
Drug solubility and molecular size: Poorly soluble drugs may require co-solvents or surfactants to improve loading during synthesis.
Careful optimization of these parameters is necessary to achieve high loading efficiency (>70%) and controlled release, which are desirable in NSAID-loaded delivery systems.[16]
Characterization Techniques for Natural Polymer?Based Silver Nanoparticles:
The physicochemical and biological properties of silver nanoparticles (AgNPs) critically determine their performance as drug delivery systems. Proper characterization is essential to evaluate particle size, morphology, surface charge, crystallinity, stability, drug encapsulation efficiency, and in vitro/in vivo behavior. Natural polymer?stabilized AgNPs require additional characterization of the polymer coating and drug–polymer interactions.
1. Particle Size and Morphology:
Techniques: Transmission Electron Microscopy (TEM), Scanning Electron Microscopy (SEM), Atomic Force Microscopy (AFM), Dynamic Light Scattering (DLS)
Purpose: Determines nanoparticle size, shape, and size distribution. Polydispersity affects drug release, cellular uptake, and biodistribution. TEM and SEM provide high-resolution images, while DLS gives hydrodynamic size in solution.
2. Surface Charge (Zeta Potential)
Technique: Zeta potential analysis (via electrophoretic light scattering)
Purpose: Measures surface charge and colloidal stability. High absolute zeta potential (> ±30 mV) indicates good dispersion stability. It also predicts interactions with biological membranes and drug adsorption efficiency.
3. Crystallinity and Phase Analysis
Techniques: X-Ray Diffraction (XRD), Selected Area Electron Diffraction (SAED)
Purpose: Determines crystalline nature and phase composition of AgNPs. Confirms formation of metallic silver and evaluates polymer influence on crystal growth.
4. Surface Chemistry and Functional Groups
Techniques: Fourier Transform Infrared Spectroscopy (FTIR), X-ray Photoelectron Spectroscopy (XPS)
Purpose: Identifies functional groups of natural polymers capping the nanoparticles and drug–polymer interactions. Confirms the presence of hydroxyl, carboxyl, or amine groups crucial for stability and drug binding.
5. Optical Properties
Techniques: UV–Visible Spectroscopy, Fluorescence Spectroscopy
Purpose: Detects Surface Plasmon Resonance (SPR) peaks characteristic of AgNPs, providing rapid confirmation of nanoparticle formation and size-dependent optical properties.
6. Thermal Stability
Techniques: Thermogravimetric Analysis (TGA), Differential Scanning Calorimetry (DSC)
Purpose: Assesses thermal degradation and polymer coating stability, which influence long-term storage and drug release behavior.
7. Drug Loading and Release Evaluation
Techniques: High Performance Liquid Chromatography (HPLC), UV–Vis Spectroscopy, Drug Release Assays
Purpose: Determines encapsulation efficiency, loading capacity, and in vitro release profile of NSAIDs from polymer?coated AgNPs.
8. Stability and Colloidal Behavior
Techniques: DLS for particle size over time, zeta potential, UV–Vis for SPR peak shift
Purpose: Evaluates long-term stability of AgNP suspensions and prevents aggregation, crucial for maintaining drug efficacy. [17]
In-vitro & In-vivo Evaluation Parameters:
The evaluation of NSAID-loaded natural polymer-based AgNPs requires systematic in-vitro and in-vivo studies to assess efficacy, safety, pharmacokinetics, and therapeutic potential.
In-vitro Evaluation Parameters:
a. Particle Size and Morphology
Ensures uniformity and stability of nanoparticles for reproducible drug delivery. Techniques: TEM, SEM, DLS.
b. Drug Encapsulation Efficiency & Loading
Determines the proportion of NSAID successfully entrapped in the polymeric AgNPs.
Techniques: HPLC, UV-Vis spectrophotometry.
c. In-vitro Drug Release Studies
Simulates controlled release in biological environments (pH-dependent or sustained).
Techniques: Dialysis membrane method or Franz diffusion cell.
d. Cytotoxicity Studies
Evaluates biocompatibility and safety of polymer-coated AgNPs.
Assays: MTT, Trypan blue exclusion, Live/dead staining using relevant cell lines.
e. Antioxidant and Anti-inflammatory Assays
Measures NSAID efficacy and AgNP contribution to anti-inflammatory effect.
In-vitro tests: Protein denaturation inhibition, DPPH radical scavenging, COX inhibition assay.[18]
In-vivo Evaluation Parameters:
a. Pharmacokinetics (PK)
Determines absorption, distribution, metabolism, and elimination of NSAID-loaded AgNPs in animal models.
Parameters: Cmax, Tmax, AUC, half-life, bioavailability.
b. Biodistribution Studies
Tracks nanoparticles in organs to evaluate targeting efficiency and potential accumulation.
Techniques: Fluorescence labeling, ICP-MS, or radio-labeling.
c. Anti-inflammatory & Analgesic Efficacy:
Tests NSAID-loaded AgNPs in inflammation models (e.g., carrageenan-induced paw edema, formalin test).
Measures reduction in swelling, pain, and inflammatory markers.
d. Toxicity Studies
Evaluates systemic toxicity, hematological, and biochemical parameters in animal models.
Includes histopathology of liver, kidney, and spleen.[19]
e. Biocompatibility & Immunogenicity
Assesses immune response (cytokine production) and compatibility with tissues.[35]
Advantages, Challenges & Safety Concerns of Natural Polymer-Based Silver Nanoparticles for NSAID Delivery:
1. Advantages: Natural polymer-based silver nanoparticles (AgNPs) offer multiple benefits in NSAID delivery:
Biocompatibility and Reduced Toxicity: Biopolymers such as arabinogalactan, pectin, and chitosan reduce cytotoxicity associated with chemically synthesized AgNPs
Eco-Friendly Synthesis: Green biofabrication eliminates hazardous reducing agents, making synthesis environmentally sustainable
Controlled Drug Release: Polymers act as capping and stabilizing agents, allowing sustained and targeted release of NSAIDs, minimizing gastrointestinal side effects
Enhanced Stability: Polymer coating prevents nanoparticle aggregation, improves shelf-life, and maintains therapeutic activity
Functionalization Potential: Surface functional groups enable targeted delivery, stimuli-responsive release, and conjugation with other therapeutic agents [36]
2. Challenges: Despite the advantages, several challenges exist:
Batch-to-Batch Variability: Natural extracts and biopolymers can vary in composition, affecting nanoparticle size, drug loading, and stability
Scale-Up Difficulties: Reproducibility and cost-effectiveness in large-scale production remain challenging due to complex biological reaction.
Drug Loading Limitations: High drug loading may destabilize nanoparticles or reduce release control.
Interaction with Biological Systems: Proteins, enzymes, and ions in vivo can alter nanoparticle properties, affecting drug delivery efficiency.
3. Safety Concerns: Safety assessment is critical due to potential cytotoxicity and bioaccumulation:
Cytotoxicity: Excessive silver ions or improperly capped AgNPs can induce oxidative stress, DNA damage, and apoptosis in cells.
Immunogenicity: Nanoparticles can trigger immune responses, inflammation, or hypersensitivity if surface properties are not optimized.
Organ Accumulation: In vivo studies show potential accumulation in liver, spleen, and kidney, emphasizing the need for controlled dosing and biodegradability.
Environmental Impact: Improper disposal of AgNPs may affect aquatic and soil ecosystems [20]
Future Scope & Research Gaps of Natural Polymer-Based Silver Nanoparticles for NSAID Delivery
Despite significant advancements in the development of NSAID-loaded natural polymer-based silver nanoparticles (AgNPs), several research gaps and opportunities remain for future exploration. Addressing these areas can enhance therapeutic efficacy, safety, and translational potential.
1. Exploration of Under-Utilized Natural Polymers
Most studies focus on common biopolymers like chitosan, alginate, or pectin. Polymers such as arabinogalactan, pullulan, gum tragacanth, and dextran derivatives remain under-explored for NSAID delivery.
Future studies should investigate these polymers for enhanced drug loading, sustained release, and targeted delivery
2. Stimuli-Responsive and Targeted Delivery Systems
Development of pH, enzyme, or temperature-responsive polymers can enable site-specific NSAID release, minimizing systemic side effects.Integration of targeting ligands or antibodies may allow selective delivery to inflamed tissues.
3. Standardization and Scale-Up Challenges
Batch-to-batch variability due to natural polymer heterogeneity remains a major hurdle.Future work should focus on standardizing polymer sources, synthesis protocols, and nanoparticle quality for reproducibility and industrial scale-up.
4. Comprehensive Safety and Toxicity Studies
Long-term in vivo toxicity, immunogenicity, and bioaccumulation studies are limited.Research is needed to evaluate chronic exposure, organ-specific effects, and nanoparticle biodegradation in animal models before clinical translation.
5. Combination Therapies and Multi-Drug Loading
Incorporating multiple NSAIDs or synergistic drugs into polymer-coated AgNPs may enhance anti-inflammatory efficacy.Future studies could explore co-delivery systems with antioxidants, analgesics, or disease-modifying agents.
6. Regulatory and Translational Research
Regulatory frameworks for nanoformulations, especially metal nanoparticles combined with natural polymers, are still evolving.
Future research should align preclinical studies with regulatory requirements, focusing on quality, safety, and efficacy metrics.[21]
7. Advanced Characterization Techniques
There is scope to implement novel imaging, spectroscopy, and high-throughput screening techniques for better understanding drug–polymer–nanoparticle interactions.Techniques like single-particle ICP-MS, cryo-TEM, and Raman mapping can provide detailed insights.
CONCLUSION:
Natural polymer-based silver nanoparticles (AgNPs) represent a promising strategy for NSAID delivery, offering advantages such as biocompatibility, controlled release, targeted delivery, and eco-friendly synthesis. The integration of under-explored polymers, such as arabinogalactan, pullulan, and gum tragacanth, provides opportunities to enhance drug loading efficiency and therapeutic performance.Despite these advantages, several challenges remain, including batch-to-batch variability, scale-up issues, potential cytotoxicity, and regulatory uncertainties. Comprehensive in-vitro and in-vivo evaluations are essential to ensure safety, efficacy, and translational potential. Additionally, the development of stimuli-responsive systems, multi-drug delivery, and standardized biofabrication protocols can significantly improve clinical applicability.Future research should focus on bridging the gap between laboratory studies and clinical translation, addressing regulatory requirements, optimizing natural polymer selection, and exploring novel characterization and targeting techniques. Overall, natural polymer-based AgNPs hold substantial promise for next-generation NSAID therapeutics, combining efficacy, safety, and sustainability.
REFERENCES:
Dhanshree P. Rathod*, T. A. Dhote, (Dr.). S. J. DighadeA Review on The Formulation, Characterization, And Therapeutic Uses of Biofabricated Silver Nanoparticles for Nsaid Delivery, Int. J. of Pharm. Sci., 2026, Vol 4, Issue 2, 141-155. https://doi.org/10.5281/zenodo.18454392
10.5281/zenodo.18454392
