Chitosan and its Derivatives in Biomedical and Pharmaceutical Sciences: From Fundamentals to Advanced Applications

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Technical Review Article | Open Access | Published 26th March 2026

Chitosan and its Derivatives in Biomedical and Pharmaceutical Sciences: From Fundamentals to Advanced Applications

Daniya Khan, Akanksha Dwivedi*, G. N. Darwhekar | EJPPS | 311 (2026) https://doi.org/10.37521/ejpps31103

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Abstract

Chitosan, a naturally derived polysaccharide obtained by the deacetylation of chitin, has emerged as a versatile biomaterial in biomedical and pharmaceutical sciences. Its unique combination of biocompatibility, biodegradability, mucoadhesiveness, and antimicrobial activity has led to widespread exploration in drug delivery, wound healing, tissue engineering, and anticancer therapy. Structural features such as reactive amino and hydroxyl groups allow for a range of chemical modifications, yielding derivatives with improved solubility, stability, and targeted functionality. This review presents a comprehensive synthesis of chitosan’s physicochemical properties, including degree of deacetylation, molecular weight, and pH-dependent solubility, and their implications in biomedical formulations. Emphasis is placed on nanoparticles, hydrogels, nanofibers, and scaffolds, along with their use in oral, ocular, nasal, and injectable drug delivery systems. Chitosan’s role in tissue regeneration is examined through applications in bone, skin, nerve, and soft tissue engineering. Moreover, it’s antimicrobial and anticancer mechanisms—including membrane disruption, gene silencing, and targeted cytotoxicity—are discussed. The review also covers biocompatibility, enzymatic degradation, and regulatory considerations, highlighting approved medical devices and commercial products. While limitations such as poor solubility at neutral pH and batch variability remain, recent innovations in chemical modification, stimuli-responsive systems, and green production methods offer promising solutions.

Keywords: Chitosan, hydrogel, nanofibers, biocompatibility, stimuli-responsive systems.

Introduction

Chitosan is a naturally occurring, linear aminopolysaccharide derived by the partial or complete deacetylation of chitin, the second most abundant biopolymer on Earth after cellulose. It is primarily extracted from the exoskeletons of crustaceans such as shrimp, crab, and lobster, although fungal and insect-derived sources are also gaining interest due to their sustainability and vegan compatibility. The structure of chitosan comprises β-(1→4)-linked D-glucosamine and N-acetyl-D-glucosamine units, conferring a high density of functional amino (-NH₂) and hydroxyl (-OH) groups which are amenable to chemical modification, enabling the generation of a wide variety of functional derivatives.¹

Over recent decades, chitosan has emerged as a highly valued biomaterial in the pharmaceutical and biomedical fields, attributed to its intrinsic properties such as biocompatibility, biodegradability, mucoadhesiveness, film-forming ability, and broad-spectrum antimicrobial activity.² Its cationic nature is unique among natural polysaccharides, allowing for electrostatic interactions with negatively charged biomolecules such as mucins, bacterial membranes, DNA, and anionic drugs.³ This makes chitosan an attractive candidate for a multitude of biomedical applications, including targeted drug delivery, wound healing, tissue engineering, antimicrobial coatings, and anticancer therapies.⁴⁻⁸

Chitosan has evolved significantly since chitin was first identified in 1811 by Henri Braconnot and later converted to “chitosan” in the late 19th century, but major scientific interest grew only in the mid-20th century when its antimicrobial, hemostatic, and film-forming properties were recognized⁹. Its functional versatility is rooted in key physicochemical parameters—particularly degree of deacetylation (DD) and molecular weight (MW). A DD above 50% is required for chitosan formation, with higher DD improving solubility in acidic media and enhancing bioadhesion³, while MW influences viscosity, mechanical strength, degradation rate, and biological interactions, where low-MW chitosan improves permeability and high-MW offers stronger structural stability¹⁰. As research remains distributed across polymer chemistry, nanotechnology, and biomedical engineering, an integrated understanding is essential. With increasing demand for sustainable, eco-friendly biomaterials, chitosan continues to stand out as a leading candidate for advanced biomedical and green technological innovations.

2. Chemical Structure and Physicochemical Properties

Chitosan is a linear, semi-crystalline polysaccharide derived by the N-deacetylation of chitin. It consists primarily of β-(1→4)-linked D-glucosamine (deacetylated unit) and N-acetyl-D-glucosamine (acetylated unit) (Figure 1).¹ The relative proportion of these two units, known as the degree of deacetylation (DD), and the polymer’s molecular weight (MW) are the primary physicochemical parameters that dictate its behaviour in biological and pharmaceutical applications.¹¹

2.1 Chemical Structure of Chitosan

The fundamental structure of chitosan features a repeating unit of glucosamine with functional –NH₂ (primary amine) and –OH (hydroxyl) groups at the C-2, C-3, and C-6 positions (Figure 1). These groups are responsible for the polymers:

● Poly-cationic nature at acidic pH (protonation of amine groups),

● High reactivity for chemical modifications (e.g., acetylation, carboxymethylation),

● Ability to chelate metals and interact with negatively charged biomolecules.⁴

Figure 1. Chemical structure of chitosan showing reactive amino and hydroxyl groups

2.2 Physiochemical properties of chitosan

The physiochemical properties of chitosan particularly its degree of deacetylation (DD), molecular weight (MW), crystallinity, and pKa, strongly influence its solubility, charge density, and biological activity. DD reflects the percentage of deacetylated glucosamine units, with chitosan defined as having >50% DD. Higher DD improves solubility in dilute acids, increases positive charge density, and enhances antimicrobial, mucoadhesive, and hemostatic properties². Techniques such as FTIR, NMR, XRD, and potentiometric titration are commonly used for DD measurement¹². Molecular weight, which ranges from 10–2000 kDa, determines viscosity, degradation rate, and tissue penetration; high-MW chitosan forms stronger gels, while low-MW variants degrade faster and penetrate tissues more easily¹⁴. Chitosan’s semi-crystalline structure depends on DD, MW, and processing methods, with solubility governed by protonation of amino groups, making it soluble in acidic solutions but insoluble above pH 6.5¹¹,¹⁵. With a pKa of ~6.3–6.5, protonated chitosan behaves as a polycation in acidic environments, enabling interactions with DNA, proteins, and negatively charged membranes, which is essential for polyelectrolyte complex formation in drug delivery systems¹⁶. Listed physiochemical properties are given in Table 1.

Table 1. Key physicochemical properties of chitosan and their biomedical implications¹⁵,¹⁶

Parameter	Key Features	Effect on Properties	Typical Applications
Degree of Deacetylation (DD)	>50% defines chitosan; higher DD = more –NH₂ groups	↑ Solubility in acids, ↑ charge density, ↑ biological activity	Wound dressings (55–70%), drug delivery (70–85%), antimicrobial/gene delivery (>85%)
Molecular Weight (MW)	10–2000 kDa	High MW: ↑ viscosity, slow degradation; Low MW: ↑ penetration, fast degradation	Hydrogels, scaffolds, permeation enhancers
Crystallinity	Semi-crystalline; depends on DD & MW	High DD → low crystallinity; high MW → high crystallinity	Determines mechanical strength & solubility
pKa (~6.3–6.5)	Protonation in acidic pH	Acidic pH: soluble & polycationic; Neutral pH: precipitates	Polyelectrolyte complexes, DNA/protein binding
Solubility	Soluble in dilute acids (1% acetic/formic acid)	Insoluble above pH 6.5 due to deprotonation	Drug delivery, coatings, gels

3. Production and Purification of Chitosan

The production of chitosan involves the extraction and subsequent deacetylation of chitin, a naturally abundant polysaccharide found in the exoskeletons of marine crustaceans (such as shrimp and crabs), insects, and fungal cell walls.¹⁷ The process typically follows a multi-step chemical or enzymatic pathway that includes demineralization, deproteinization, decolourization, and deacetylation. Each step plays a critical role in removing non-polysaccharide components and yielding high-purity chitosan suitable for biomedical use.¹⁸,¹⁹

3.1 Sources of Chitin

The most common raw materials used for chitosan production include:

● Crustacean shells: shrimp, crab, lobster - by-products of seafood processing.

● Fungi (e.g., Mucor spp.): a vegan and allergen-free alternative gaining commercial interest.

● Insect cuticles: an emerging sustainable source under exploration.

The choice of source influences the molecular weight, acetylation degree, purity, and environmental impact of chitosan.¹⁹

3.2 Chemical Extraction Process

The traditional chemical method is widely employed due to its simplicity, cost-effectiveness, and scalability.²⁰ The steps are Figure 2:

Figure 2. Flow diagram of chemical chitosan production from crustacean shells

3.3 Biological (Enzymatic) Production

An environmentally friendly alternative is enzymatic deacetylation using chitin deacetylase enzymes derived from fungi or bacteria.

This method:

● Preserves polymer chain integrity,

● Allows for controlled DD and MW,

● Avoids high chemical waste.

However, challenges include:

● High cost of enzymes,

● Long reaction times,

● Lower yields than chemical methods.²²

3.4 Industrial and Environmental Considerations

While chemical deacetylation is industrially dominant, it generates large volumes of alkaline and acidic wastewater, raising environmental concerns. Hence, there's growing interest in:

● Enzymatic or microbial fermentation processes,

● Integrated valorization of seafood waste (zero-waste biorefineries),

● Green solvents and ionic liquids for extraction.

Comparison of chemical and enzymatic production methods is given in Table 2.

Table 2. Comparison of chemical vs. enzymatic production methods

Parameter	Chemical Method	Enzymatic Method
Cost	Low	High
Reaction time	Short (hours)	Long (days)
Environmental impact	High (acid/alkali effluents)	Low
Product purity	Moderate to high	Very high
Industrial scalability	Well established	Emerging

3.5 Purification for Biomedical Use

For chitosan intended for pharmaceutical or medical applications, further purification is necessary:

● Dialysis to remove salts and acids,

● Filtration to remove insoluble particles,

● Lyophilization or spray drying to obtain powder form,

● Characterization to determine DD, MW, viscosity, and purity.

Residual protein, ash, and endotoxin levels must meet regulatory thresholds to ensure biocompatibility and non-immunogenicity.⁶

The production of chitosan is a crucial step that affects its final properties and applications. While chemical deacetylation remains the mainstream method, efforts to develop green, enzyme-based techniques are gaining momentum to address environmental sustainability. Future innovations will likely focus on optimizing yield, purity, and scalability while minimizing environmental burden is an essential consideration for chitosan’s expanding role in biomedicine.²¹

4. Chitosan Derivatives and Chemical Modifications

Although native chitosan possesses favourable biomedical attributes such as biocompatibility, bioadhesion, and antimicrobial activity, its practical applications are limited by several physicochemical drawbacks - namely poor water solubility at physiological pH, mechanical fragility, and low processability. To address these limitations and expand the range of its functionalities, a wide variety of chitosan derivatives have been synthesized via targeted chemical modifications of its primary amine (–NH₂) and hydroxyl (–OH) groups.²³

4.1 Sites for Chemical Modification

The structure of chitosan contains several reactive groups:

● C2 position: primary amine (–NH₂) group,

● C3 and C6 positions: secondary and primary hydroxyl (–OH) groups.

These allow chitosan to undergo a wide range of chemical reactions, including acetylation, alkylation, carboxymethylation, quaternization, phosphorylation, and graft copolymerization.²

Figure 3. Functional groups of chitosan susceptible to chemical modification 23 — **Figure 3.** Functional groups of chitosan susceptible to chemical modification ²³

4.2 Chitosan Derivatives and Their Biomedical Applications

To support the discussion on chemical modifications of chitosan, Table 3 provides a concise overview of the major derivatives, their synthesis routes, key physicochemical features, and associated biomedical applications. This summary highlights how specific modifications enhance solubility, bioactivity, stability, and functional performance, allowing chitosan derivatives to be effectively used in drug delivery, wound healing, antimicrobial coatings, and tissue engineering. These strategies yield derivatives suitable for physiological pH environments, enabling injectable forms, mucoadhesive formulations, and targeted nanoparticle systems. Chitosan’s chemical versatility enables the development of a wide range of derivatives tailored to specific therapeutic goals. By modifying reactive groups, researchers can overcome the inherent limitations of native chitosan and engineer advanced biomaterials for use in regenerative medicine, controlled drug release, antimicrobial treatment, and cancer therapy. These derivatives are foundational to next-generation bioresponsive and patient-specific medical platforms.²⁸

Table 3. Comprehensive Overview of Chitosan Derivatives and Chitosan Nanoparticle (CNP) Systems with their Synthesis, Properties, and Biomedical Applications

Category	Subtype / Formulation	Synthesis / Preparation Route	Modification Site / Composition	Key Physicochemical Features	Refs
Chitosan Derivatives	Carboxymethyl Chitosan (CMC)	Carboxyalkylation using monochloroacetic acid under alkaline conditions	–NH₂, –OH	Highly water-soluble, amphoteric, mucoadhesive	(24)
	Quaternized Chitosan	N-quaternization using GTMAC	–NH₂	Permanent cationic charge, pH-independent solubility, high mucoadhesion	(25)
	Alkylated Chitosan	Reaction with alkyl halides under mild alkaline conditions	–NH₂	Amphiphilic, forms micelles and self-assembled nanoparticles	(26)
	Sulfated Chitosan	Sulfation using SO₃–DMF complex / chlorosulfonic acid	–OH	Anti-inflammatory, anticoagulant, heparin-mimetic	(27)
	Phosphorylated Chitosan	Phosphorylation using phosphorus acid + formaldehyde	–NH₂	Calcium chelation, enhanced osteogenesis	(28)
	Graft Copolymers (PEG, PLA, PNIPAAm-g-CS)	Radical polymerization, enzymes, or ionic grafting	–NH₂ or –OH	Thermo/pH responsiveness, high flexibility	(29)
	Crosslinked Chitosan Networks	Crosslinking with glutaraldehyde, genipin, sulfuric acid	Matrix-wide	High mechanical strength, stability, controlled swelling	(29)
Chitosan Nanoparticle Systems (CNPs)	Chitosan–TPP Nanoparticles	Ionic gelation with tripolyphosphate (TPP)	CS + TPP	Protects proteins/peptides; enhances stability	—

5. Chitosan-Based Nanotechnology and Advanced Delivery Systems

Over the last twenty years, nanotechnology has greatly advanced biomedical science by enabling precise drug delivery, improved diagnostics, and engineered tissue systems. Within this field, chitosan-based nanostructures have become highly popular because chitosan is naturally biocompatible, biodegradable, mucoadhesive, and easily modified. Its polycationic nature and reactive functional groups allow it to be shaped into multiple nanoscale architectures—including nanoparticles, nanofibers, nanocomposites, and nanogels—that support targeted, controlled, and sustained therapeutic delivery³⁰. Chitosan nanoparticles (CNPs), usually 50–500 nm in size, are among the most widely used systems. They can transport drugs, genes, proteins, and vaccines, and are prepared using methods such as ionic gelation with TPP, polyelectrolyte complexation, emulsification–solvent evaporation for hydrophobic drugs, and scalable approaches like spray-drying and nanoprecipitation³¹. CNPs enhance the solubility and bioavailability of drugs such as curcumin and paclitaxel, improve nucleic acid protection and cellular uptake in gene delivery, and strengthen mucosal immunity when used in oral and nasal vaccines for diseases such as hepatitis B and influenza³²,³³.

In addition to nanoparticles, chitosan nanocomposites combine chitosan with inorganic nanofillers such as silver, gold, ZnO, or graphene oxide to achieve multifunctionality. These hybrid systems offer antimicrobial effects, mechanical strengthening for bone and cartilage repair, and theranostic capabilities that integrate diagnosis and treatment - for example, CS/AgNPs for wound healing, CS–ZnO for dental and orthopedic implants, and CS–graphene scaffolds for nerve regeneration or biosensing (34). Chitosan nanofibers produced by electrospinning generate porous, high-surface-area mats that mimic extracellular matrix structure, making them useful for wound dressings, tissue-engineered constructs for skin, bone, and nerve repair, and localized drug-eluting implants³⁵. Chitosan-based nanogels and hydrogels, formed through physical or chemical crosslinking, swell in aqueous environments and allow stimuli-responsive drug release, making them effective for cancer therapy, oral delivery, and infection-responsive antimicrobial systems³⁷. Similarly, 3D chitosan scaffolds combined with materials such as collagen, gelatin, or hydroxyapatite provide structural integrity and diffusion pathways and are widely used for bone regeneration, cartilage repair, and neural conduit fabrication³⁸.

More recently, advanced multifunctional chitosan theranostic platforms have been developed by integrating targeting ligands (e.g., folic acid), imaging agents, and dual drug combinations, enabling simultaneous diagnosis, targeted delivery, and therapy³⁹. Overall, chitosan nanotechnology benefits from key advantages—biodegradability, mucoadhesiveness, cationic charge for strong drug/gene binding, tunable physicochemical properties, and broad chemical modifiability, making it one of the most versatile and promising biomaterials for next-generation drug delivery, tissue engineering, and precision medicine applications.

6. Drug Delivery Applications of Chitosan

Chitosan is widely used as a versatile excipient in drug delivery systems because it is biodegradable, biocompatible, mucoadhesive, pH-responsive, and non-toxic. Its natural positive charge enables strong interactions with negatively charged membranes, improving drug retention, permeation, and cellular uptake. Chemical modification further expands its suitability for oral, nasal, ocular, transdermal, and parenteral routes⁴⁰. In oral delivery, chitosan prolongs gastrointestinal residence, enhances paracellular transport, and enables pH-responsive release -seen in chitosan-TPP insulin nanoparticles, quaternized chitosan microspheres, and chitosan-coated liposomes for gastro-retentive formulations⁴¹. For nasal delivery, its mucoadhesive and permeation-enhancing nature supports rapid systemic and even nose-to-brain absorption, useful in CS-DNA nasal vaccines, CS-insulin sprays, and CS nanoparticles for olanzapine targeting⁴². In ocular delivery, chitosan improves precorneal retention and transcorneal permeability through systems such as CS–hyaluronic acid nanogels, CS-coated nanoparticles, and CS hydrogels for sustained release³¹. For transdermal and topical uses, chitosan forms antimicrobial, healing-promoting films, patches, and hydrogels, including CS-ZnO nanogels, CS-honey hydrogels, and CS-based NSAID patches³¹,³⁷. In injectable and parenteral formulations, chitosan enables controlled drug and gene delivery through CS-PLGA paclitaxel nanoparticles, CS-DNA complexes, and injectable CS hydrogels for prolonged analgesia⁴³. It is also effective for buccal, vaginal, and rectal routes due to mucoadhesion and enzyme protection, such as CS-ibuprofen buccal films, CS antifungal vaginal gels, and CS-5-FU rectal suppositories⁴⁴. Additionally, chitosan is central in smart and targeted delivery systems, including pH-responsive tumor-targeting hydrogels, thermo-responsive nanogels, and ligand-modified nanoparticles for precision therapy. Overall, its chemical tunability and compatibility with diverse drugs make chitosan a key material for modern, non-invasive, and stimuli-responsive drug delivery technologies. Chitosan based drug delivery and their benefits are given in Table 4.

Table 4. Chitosan-Based Drug Delivery Systems Across Different Routes and Their Key Benefits

Delivery Route / System	Formulation Type	Drug / Gene	Target Site	Key Outcome / Benefit
Oral Delivery	Chitosan nanoparticles	Insulin	GI tract	Enhanced stability and oral bioavailability
	Chitosan microspheres	5-Fluorouracil (5-FU)	Intestine	Controlled intestinal release
	Chitosan-coated liposomes	Metformin	GI tract	Sustained absorption and gastro-retentive release
	N,O-CMC capsules	Diclofenac	Colon	pH-sensitive colon-targeted delivery
Nasal Delivery	Chitosan–DNA nanoparticles	Plasmid DNA	Nasal mucosa / immune system	Improved nasal vaccination response
	Chitosan spray	Insulin	Systemic circulation	Enhanced plasma insulin, rapid absorption
	CS nanoparticles	Olanzapine	Brain	Effective nose-to-brain targeting
Ocular Delivery	CS-HA nanogels	Timolol	Eye (glaucoma)	Increased retention, better intraocular pressure control
	CS-coated nanoparticles	Ketorolac	Cornea	Improved anti-inflammatory action
	CS hydrogels	Bupivacaine or other drugs	Ocular surface	Sustained release ocular inserts
Transdermal / Topical	CS-ZnO nanogels	—	Skin	Antibacterial wound dressing
	CS-honey hydrogels	—	Diabetic wounds	Faster wound healing
	CS patches	NSAIDs	Skin	Local pain management
Parenteral Delivery	CS-PLGA nanoparticles	Paclitaxel	Tumor	Higher cytotoxicity with fewer side effects
	CS-DNA nanoplex	VEGF plasmid	Ischemic tissue	Enhanced angiogenesis
	Injectable CS hydrogel	Bupivacaine	Surgical site	Prolonged postoperative analgesia
Buccal / Vaginal / Rectal	CS buccal films	Ibuprofen	Oral mucosa	Relief of oral ulcers
	CS vaginal gels	Antifungal drug	Vaginal tissue	Effective treatment of Candida infections
	CS suppositories	5-FU	Colon / rectum	Localized colorectal cancer therapy

7. Wound Healing and Tissue Engineering Applications of Chitosan

Chitosan has emerged as a multifunctional biomaterial in wound healing and tissue engineering due to its biodegradability, biocompatibility, haemostatic properties, antimicrobial activity, and ability to form porous, cell-supportive structures. Its structural similarity to glycosaminoglycans (GAGs) found in the extracellular matrix (ECM) and its cationic nature make it an ideal candidate for scaffolds, hydrogels, membranes, and nanofiber constructs used in regenerative therapies.⁴⁵ In wound management, chitosan helps maintain a moist environment, promotes cell migration, and protects against infection. Its positive amine groups trigger platelet aggregation for rapid clot formation, while its antimicrobial effects disrupt the membranes of pathogens such as S. aureus, E. coli, and P. aeruginosa. Chitosan also stimulates macrophages, fibroblasts, and growth factor release, accelerating tissue repair⁴⁶. It can be processed into films for superficial wounds, hydrogels for burns and chronic ulcers, nanofibers that mimic the extracellular matrix, and highly absorbent sponges for deep wounds³⁷,⁴⁴. Clinical products such as HemCon®, ChitoFlex®, and CuraMatrix® demonstrate the real-world use of chitosan dressings in trauma care and dermal regeneration³⁶,⁴⁷,⁴⁸. In tissue engineering, chitosan’s structural similarity to natural ECM makes it ideal for supporting cell attachment and tissue formation. CS–hydroxyapatite scaffolds promote bone formation, CS–collagen systems enhance skin repair, and electroconductive CS composites containing polypyrrole or graphene oxide aid in nerve regeneration. Chitosan hydrogels also support cardiovascular tissue repair by promoting angiogenesis and mimicking cardiac elasticity³⁰,³⁸,⁴⁹. Additionally, chitosan-based scaffolds deliver stem cells and growth factors such as TGF-β1, BMP-2, and VEGF to enhance regeneration⁵⁰. Its biodegradability, which depends on DD, crosslink density, and polymer blending, allows scaffold breakdown to match tissue growth. Because of these combined advantages and the availability of FDA-approved products, chitosan remains a key biomaterial in regenerative medicine and wound healing³⁸. Wound healing and tissue engineering systems with their applications are described in Table 5.

Table 5. Chitosan-Based Wound Healing and Tissue Engineering Systems with their Applications and Key Benefits

System Type	Form / Composite	Target Tissue / Application	Key Therapeutic Benefits	Refs
Wound Healing Systems	Chitosan Film	Superficial wounds, abrasions	Protective barrier, antimicrobial, hydration maintenance	(37,44)
	Chitosan Hydrogel	Chronic wounds, burns, diabetic ulcers	Moisture retention, drug/growth factor loading, oxygen exchange	(37,44)
	Chitosan Nanofiber Mat	Surgical wounds, infected wounds, burns	ECM mimicry, rapid healing, enhanced cell migration	(37,44)
	Chitosan Sponge/Foam	Deep wounds, hemorrhagic wounds	High absorbency, strong hemostatic action	(37,44)
	HemCon®, ChitoFlex®	Trauma, battlefield injuries	FDA-approved hemostatic control	(36,47,48)
	CuraMatrix®	Dermal regeneration	Accelerated healing via collagen–CS scaffold	(36,47,48)
Tissue Engineering Scaffolds	CS–Hydroxyapatite	Bone tissue	Osteogenesis, mineralization	(30,38,49)
	CS–Collagen	Skin and dermal tissue	Angiogenesis, re-epithelialization	(30,38,49)
	CS–Polypyrrole / CS–Graphene	Nerve tissue	Neuroconductivity, axonal regrowth	(30,38,49)
	CS–Alginate	Cartilage	Chondrocyte proliferation, ECM production	(30,38,49)
Stem Cell & Growth Factor Systems	CS Scaffold + MSCs	Soft tissue / bone regeneration	Improved tissue repair and cell survival	(50)
	CS Hydrogel with TGF-β1, BMP-2, VEGF	Regenerating tissues	Controlled release, enhanced matrix deposition	(50)

8. Antimicrobial and Anticancer Applications of Chitosan

Chitosan and its derivatives exhibit potent antimicrobial and anticancer activities due to their cationic nature, biocompatibility, and surface-modifiable structure. These properties have led to their incorporation in wound dressings, food preservatives, anticancer drug delivery systems, and medical coatings to address microbial resistance and enhance therapeutic efficacy.⁵¹,⁵²

Chitosan shows strong antimicrobial and anticancer activity through multiple biological mechanisms, making it a highly valuable biopolymer in modern medicine. Its antimicrobial effect works mainly through the positive –NH₃⁺ groups, which bind to negatively charged microbial membranes and cause membrane disruption, leakage of cell contents, and eventual cell death. Chitosan can also chelate essential metals like Fe²⁺ and Mg²⁺, weakening microbial enzymes and membrane stability. In some cases, chitosan enters the cell and binds to DNA or RNA, inhibiting mRNA synthesis and stopping microbial growth. Additionally, when applied as a film or coating, it forms a physical barrier that prevents colonization on wounds or medical devices. These mechanisms together make chitosan effective against Staphylococcus aureus, E. coli, Pseudomonas aeruginosa, Candida albicans, and even drug-resistant strains²⁰,⁵¹,⁵³,⁵⁴.

In cancer therapy, chitosan and its derivatives act through direct and indirect mechanisms. They can induce apoptosis and oxidative stress in tumour cells, enhance the delivery and bioavailability of chemotherapy drugs, or target specific cancer cells using ligands such as folic acid or transferrin. Chitosan nanoparticles also protect genetic materials like siRNA and plasmids, enabling effective gene therapy—for example, delivering anti-VEGF siRNA to block tumour angiogenesis or delivering p53 plasmids to restore tumour suppressor function. Chitosan nanocarriers can release drugs specifically in the acidic tumour microenvironment and can be combined with agents such as gold nanorods for synergistic photothermal and chemotherapy effects²⁴,⁵²,⁵⁶⁻⁵⁹. With proven antimicrobial and anticancer activity, low toxicity, and easy chemical modification, chitosan stands out as a safe, green, and highly adaptable platform for developing next-generation therapeutics, especially in an era of antibiotic resistance and the need for targeted cancer treatments⁶⁰. Figure 4 & Figure 5 contains anticancer and antimicrobial mechanism of chitosan.

Figure 4. Anticancer mechanism of chitosan

Figure 5. Antimicrobial mechanism of chitosan

9. Biocompatibility and Toxicological Studies of Chitosan

Chitosan is widely recognized as a biocompatible, biodegradable, and non-toxic biomaterial, but its safety still depends on factors such as molecular weight, degree of deacetylation, purity, dose, and formulation type⁴⁶,⁶¹. In in-vitro studies, chitosan typically shows excellent cell compatibility in fibroblasts, keratinocytes, and HEK293 cells, with low- and medium-MW forms being the safest, although very high concentrations or highly crosslinked structures may cause mild cytotoxicity or oxidative stress⁶². In-vivo evaluations in rats, rabbits, mice, and pigs show minimal inflammation, no necrosis, normal blood biochemistry, and no systemic toxicity even at doses up to 100 mg/kg, with chitosan sponges and hydrogels promoting granulation and epithelialization in wound healing⁴⁸,⁶³. Chitosan is also haemocompatible, causing less than 5% haemolysis, no platelet activation, and only mild transient immune responses; in some cases, low-MW chitosan even acts as a vaccine adjuvant, although impure or high-dose formulations may cause slight inflammation⁶⁵. Regulatory agencies such as the FDA recognize chitosan as safe (GRAS), and several products—including HemCon®, ChitoFlex®, and dietary-grade ChitoClear™—are already approved, although issues like batch variability and the need for GMP-compliant production still limit injectable formulations⁶⁶,⁶⁷. Toxicology studies confirm that chitosan has a high safety margin, with oral and dermal LD₅₀ values above 5000 mg/kg, no genotoxicity, and no long-term organ or reproductive toxicity. Overall, chitosan is a highly safe and adaptable biomaterial, and its future clinical success will depend on improving standardization and manufacturing consistency⁶²,⁶⁶. Table 6 contains Biocompatibility, In-Vitro/In-Vivo Findings, and Regulatory Status of Chitosan-Based Formulations.

Table 6. Biocompatibility, In-Vitro/In-Vivo Findings, and Regulatory Status of Chitosan-Based Formulations

Category	Formulation / Product Type	Model / Cell Line / Application	Key Biocompatibility or Safety Outcome	Refs
In-Vitro Biocompatibility	CS nanoparticles	L929 fibroblasts	>90% viability up to 1000 µg/mL	(62)
	CS hydrogel (1% w/v)	Human keratinocytes	Enhanced proliferation over 48 h	(62)
	CS-TPP/DNA nanoplex	HEK293 cells	Non-toxic, efficient gene transfection	(62)
	CS–silver nanocomposite	A549 lung cells	Mild ROS only at >500 µg/mL	(62)
In-Vivo Biocompatibility	CS sponges/hydrogels	Rat/mouse wound models	Granulation tissue formation, epithelialization	(48,63)
	Injectable CS nanoparticles	Systemic administration	Normal blood chemistry, no organ toxicity	(48,63)
	Subcutaneous CS implants	Rat/rabbit models	Minimal inflammation, no necrosis	(48,63)
Hemocompatibility & Immunogenicity	CS hydrogels & NPs	Blood-contact tests	<5% hemolysis, no platelet/complement activation	(65)
	Low-MW CS	Immune stimulation	Mild immunomodulation; vaccine adjuvant potential	(65)
Regulatory & Clinical Status	HemCon®	Chitosan gauze (wound care)	FDA/CE approved	(66,67)
	ChitoClear™	Dietary chitosan	FDA GRAS-listed	(66,67)
	Novatein®	CS hydrogel	Under clinical trials	(66,67)
Toxicology	Chitosan (general)	Rodent oral/dermal studies	LD₅₀ > 5000 mg/kg; non-toxic	(62)
	Long-term exposure	90-day rodent models	No liver/kidney damage; no tumour formation	(62,66)
	Genetic safety	Ames & micronucleus assays	No genotoxicity or mutagenicity	(62,66)

10. Marketed Products and Regulatory Landscape of Chitosan

Chitosan has gained strong commercial importance because it is safe, biodegradable, and highly versatile, making it useful in wound care, drug delivery, dietary supplements, and cosmetics. The global market was valued at USD 6.8 billion in 2019, growing at a 24.7% CAGR (2020–2027) due to increasing demand for eco-friendly polymers, rising nutraceutical/cosmeceutical products, and supportive regulations. Several FDA- and CE-approved chitosan wound products—such as HemCon®, ChitoFlex® Pro, and Celox™—are widely used in trauma and surgical care, while dietary products like ChitoClear™ and LipoSan Ultra® are marketed for cholesterol and weight management. Chitosan is also used in cosmetics for its hydrating, antimicrobial, and film-forming properties, and clinical-stage chitosan-based medical devices like Novatein® show promise in tissue regeneration. Commercial growth is supported by a strong patent landscape (20,000+ patents from 2000–2022) targeting nanocarriers, hydrogels, scaffolds, and stimuli-responsive systems. Regulatory acceptance is also expanding: the FDA considers chitosan GRAS, Europe markets multiple CE-approved devices, and Asia (China, Japan) leads in industrial production and approvals. Although challenges such as raw material variability, solubility issues, and lack of standardization still limit some applications, future opportunities include smart tissue-specific biomaterials, 3D bioprinting inks, cancer immunotherapy carriers, and green manufacturing processes. Altogether, chitosan has successfully transitioned into global markets and is poised to support next-generation biomedical technologies⁶⁷⁻⁷¹. Commercial products and application are given in Table 7.

Table 7. Selected Chitosan-Based Commercial Products & Applications

Product Name	Form	Application	Approval Status	Reference
HemCon®	Gauze pad	Trauma wound dressing	FDA, CE approved	(67–71)
ChitoFlex® Pro	Dressing	Surgical and diabetic wound care	FDA approved	(67–71)
Celox™	Granules	Emergency bleeding control	CE certified; US military use	(67–71)
ChitoClear™	Capsules	Dietary supplement for lipid/weight control	FDA GRAS-listed	(67–71)
LipoSan Ultra®	Powder	Weight and fat binding management	Dietary market	(67–71)
Novatein®	Injectable hydrogel	Soft tissue regeneration	Under clinical trials (US/EU)	(67–71)

11. Challenges, Limitations, and Future Perspectives

Chitosan holds remarkable potential in biomedical and pharmaceutical fields, yet several challenges still limit its full clinical and industrial adoption. Scientifically, its poor solubility at physiological pH, batch-to-batch variability from natural sources, and weak mechanical strength demand chemical modification or composite reinforcement, which may affect biocompatibility⁷²,⁷³. Formulation-wise, chitosan suffers from limited aqueous solubility, uncontrolled degradation, sterilization difficulties, and scaling issues for nanoparticle production, all of which reduce reproducibility and drug-loading efficiency. Regulatory progress is slowed by the lack of harmonized global standards, absence of a dedicated pharmacopeial monograph, and varying toxicity/biocompatibility guidelines across agencies. Environmental concerns include reliance on marine sources, allergen risks, and sustainability issues, which are driving interest in fungal and insect-derived chitosan. However, future directions remain promising: green production methods such as enzymatic deacetylation and microbial fermentation, development of smart stimuli-responsive systems for tumour targeting and controlled antimicrobial release, and theranostic platforms combining imaging with therapy⁷⁴. Advancements in 3D bioprinting, chitosan-based bioinks, and blends with HA, gelatin, and alginate are accelerating tissue engineering, while AI-powered modeling is improving predictions of chitosan–drug interactions and scaffold behaviour⁷⁵. Ultimately, overcoming these limitations will require strong interdisciplinary collaboration across materials science, biotechnology, clinical research, and regulatory bodies to establish unified standards and enable successful translation of next-generation chitosan technologies⁷⁶.

Conclusion

Chitosan has proven to be one of the most promising and extensively studied natural polymers in the biomedical and pharmaceutical domains. Its biodegradability, biocompatibility, mucoadhesiveness, antimicrobial activity, and chemical versatility offer a unique foundation for designing multifunctional delivery systems, regenerative scaffolds, wound healing matrices, and even advanced theranostic platforms. Throughout this review, we have systematically presented the structural, physicochemical, and biological characteristics of chitosan and outlined how they contribute to its performance across a wide range of applications. The development of chitosan derivatives—such as carboxymethyl, quaternized, phosphorylated, and sulfated forms—has significantly expanded its utility, especially in environments where native chitosan's limitations (e.g., poor solubility at physiological pH) are critical. In the context of nanotechnology, chitosan has enabled the creation of responsive, targeted, and efficient delivery systems for small molecules, proteins, and genetic materials. Its integration into hydrogels, nanofibers, and composite scaffolds has revolutionized wound healing and tissue engineering strategies by promoting angiogenesis, cellular proliferation, and extracellular matrix remodeling. In addition, its inherent antimicrobial and anticancer properties—further enhanced by nanocomposite technologies—underscore its potential as both a therapeutic and prophylactic agent. Despite these advances, challenges remain in terms of standardization, batch consistency, mechanical stability, and regulatory harmonization. Addressing these issues through green synthesis methods, smart material design, AI-assisted modeling, and interdisciplinary collaboration will be critical for chitosan’s translation into next-generation biomedical products. The emergence of chitosan-based products in the commercial market, including FDA- and CE-approved wound dressings, dietary supplements, and cosmetic formulations, validates its clinical safety and efficacy. With growing interest in sustainable, naturally derived biomaterials, chitosan stands at the forefront of eco-friendly innovations capable of meeting the complex needs of modern medicine. Chitosan is not merely a biomaterial of interest, it is a versatile platform at the intersection of green chemistry, biotechnology, nanomedicine, and personalized therapeutics. Future research, empowered by cutting-edge material science, regulatory alignment, and translational strategies, will further cement chitosan’s role in shaping the next era of smart, sustainable, and patient-centered healthcare solutions.

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