Revolutionizing Wound Care with Chitosan-Based Biomaterials

A wound is an injury that happens to a living tissue breaking the skin and mucous membrane and in turn causing pain and infection. It can be due to chemical, mechanical, or thermal trauma such as cut, blow, burn, pressure or any other impact on to the skin. It may also develop due to diseases like diabetes mellitus immunologic diseases or arterial insufficiency. A wound may vary in the appearance depending on location of injury, depth of injury, injury mechanism, acute vs chronic and wound sterility. Treatment strategies for wound healing will depend on classification of wound, whether acute or chronic.^1,2

Figure 1: Types of wounds³

Figure 2: Wound classification with respect to thickness, complexity, age and origin⁴

WOUND HEALING

Wound healing is a highly coordinated complex biological process that restores the integrity as well as the function of injured tissue. It maintains haemostasis and prevents infection on the injured tissue. It involves a complex interaction of cellular and molecular mechanisms which includes inflammation, tissue regeneration and remodelling. The process is highly influenced by factors like age, infection, comorbidities (for ex. Diabetes mellitus) and whether the wound is acute or chronic.^4,5

STAGES OF WOUND HEALING

The process of wound healing advances through four overlapping and distinct phases.

Stage 1: HAEMOSTASIS

This is an immediate response to any injury, which aims to stop bleeding. On injury, blood vessels constrict causing vasoconstriction, and the platelets aggregate, forming a fibrin clot, which also serves as a temporary matrix to support cell migration and the release of signalling molecules.

Stage 2: INFLAMMATION

This phase begins within four hours of injury and may last for several days. During this stage, vasodilation occurs, leading to infiltration of immune cells like macrophages and neutrophils to the wound site. This phase is essential for preparing wound bed and for tissue regeneration.

Stage 3: PROLIFERATION

The main characteristic of this phase is tissue regeneration and matrix formation. Fibroblasts produce extracellular matrix components like collagen and fibronectin. The wound is re-epithelised with keratinocytes. New blood vessels are formed from endothelial cells through angiogenesis which restores oxygen as well as nutrient supply. Granulation tissue fills the wound bed, serving as a platform for further development.

Stage 4: REMODELLING (maturation)

This is the final phase of wound healing that can last for several weeks and months. Here type III collagen is replaced by type I stronger collagen, tensile strength is increased by crosslinking and reorganization of collagen fibres. Extracellular matrix gets degraded by matrix metalloproteinases, normal tissue architecture is restored.

Understanding of all the phases of wound healing process is essential for designing proper wound healing strategies.^6,7,8

Table 1: Factors affecting wound healing^8,9

Figure 2: Different treatment strategies used for wound healing

Even though, the body has the ability to heal itself, sometimes wounds fail to heal by normal process, leading to chronic wounds like pressure sores, diabetic foot ulcers, and venous leg ulcers. These chronic wounds can impact the quality of life of the patients and can cause a significant burden to healthcare. Thus, the development of advanced wound care materials is very essential, especially those that promote faster wound healing as well as prevent infection.

Among varieties of biomaterials Chitosan based materials are of growing interest. Chitosan is a natural polysaccharide explored for wound healing, which is derived from chitin. It has gained attention due to its biodegradability, biocompatibility, non-toxicity, and antimicrobial and haemostatic properties. Chitosan based formulations ranging from films and hydrogels to nanoparticles and scaffolds have shown excellent promise in promoting wound healing.⁴

CHITOSAN

Chitosan is a biodegradable polysaccharide obtained by deacetylation of chitin, which is extracted from the shells of crustaceans like crab, lobster, shrimp etc., insects and fungal cell walls. Chemical composition of chitosan consists of β-(1     4)- linked D-glucosamine and N-acetyl-D-glucosamine units.^10,11

Figure 3: Structure of Chitosan

Figure 3: Properties of chitosan¹⁰

Chitosan is a highly attractive biomaterial due its properties as well as its availability. It has vast biomedical applications, particularly in the field of wound healing.⁴

PREPARATION OF CHITOSAN

The deacetylation of chitin is the basis for both chemical and enzymatic processes that convert it to chitosan. In order to create D-glucosamine units, which contain free amino groups and improve the polymers' solubility in aqueous conditions, acetyl groups from N-acetylglucosamine are removed during the process of deacetylation, which turns chitin into chitosan. Acetamide groups are chemically hydrolysed at higher temperatures and in highly alkaline atmosphere. Typically, the reaction is conducted in a heterogeneous phase with concentrated KOH or NaOH solutions (40–50%) at temperatures over 100°C, preferably in an inert atmosphere to prevent the polymer from depolymerizing. The source of the material utilized and the desired level of deacetylation are a couple of the variables that affect the reaction's specific conditions. To create biological chitosan, enzymatic techniques employing chitinases or chitin deacetylases are a viable alternative. For the first time, these enzymes were discovered and partially isolated from Absidia coerulea and Mucor roxii fungal extracts.^11,12

Table 2: General properties and grades of Chitosan^10,13

The most remarkable feature of chitosan is its bioactivity in the wound environment, where it exerts multiple effects that jointly enhance the healing process. Because of the positively charged amino groups at physiological pH, chitosan can interact with bioactive molecules and negatively charged cell membrane, leading to diverse biological effects.

Chitosan contributes to various phases of wound healing cascade through different mechanisms such as haemostatic activity, stimulation of cell proliferation and migration, anti-inflammatory effect, promotion of collagen synthesis, moisture retention and barrier formation.⁴

 HEMOSTSTIC ACTIVITY:

Chitosan promotes platelet adhesion and aggregation, which in turn facilitates rapid blood clot formation useful in trauma or surgical wounds.

STIMULATION OF CELL PROLIFERATION AND MIGRATION:

Chitosan aids the migration and proliferation of fibroblasts, endothelial cells and keratinocytes which promotes proliferation as well as enhance granulation tissue formation and reepithelization.

ANTI-INFLAMMATORY EFFECTS:

Chitosan regulates inflammatory response by reducing infiltration of inflammatory cells and supressing cytokines. This can favour wound healing.

PROMOTION OF COLLAGEN SYNTHESIS AND EXTRACELLULAR MATRIX REMODELLING:

Chitosan stimulate fibroblast to produce collagen and extra cellular matrix proteins, thereby supporting tissue remodelling and restoring skin structure.

MOISTURE RETENTION AND BARRIER FORMATION:

Chitosan based films and hydrogels provide moist wound environment, which can promote healing process and act as physical barrier to many contaminants.⁴

ANTIMICROBIAL ACTIVITY OF CHITOSAN

One of the most important advantages of chitosan in wound healing application is its broad-spectrum antimicrobial activity. It is effective against both gram-positive and gram-negative bacteria as well as fungi. The antimicrobial mechanism is primarily due to electrostatic interactions, inhibition of nutrient uptake, chelation of essential ions and DNA binding.^14,15

ELECTROSTATIC INTERACTIONS:

Chitosan binds to negatively charged bacterial cell walls because of its polycationic nature. This binding disrupts membrane integrity which leads to leakage of intracellular contents.

INHIBITION OF NUTRIENT UPTAKE:

Chitosan forms a polymeric barrier around microbial cells thereby inhibiting nutrient transport and metabolism.

CHELATION OF ESSENTIAL IONS:

Chitosan chelates essential trace elements like Ca²⁺, Fe²⁺, Mg²⁺ etc., which disrupts microbial enzymes and growth.

DNA BINDING:

Low molecular weight chitosan can penetrate bacterial cells, binds to DNA, thereby interfering transcription and replication.¹⁵

APPLICATION OF CHITOSAN BASED FORMULATION FOR WOUND HEALING

CHITOSAN FILMS AND MEMBRANES:

Chitosan films and membranes are now being utilized for its biodegradability, mechanical flexibility, non-irritancy, compatibility with wide range of materials, moisture retaining capacity as well as antimicrobial effect. Chitosan films serve multiple functions as wound dressing, they form a protective barrier against microbial invasion and mechanical trauma. They also maintain a moist environment for tissue repair and allows gaseous exchange which is essential for maintaining cellular activity. Moreover, chitosan films have shown its ability in skin tissue engineering by acting as a base for supporting cell attachment, proliferation and differentiation. Many studies explore the versatility of chitosan for acute wound, ulcers, surgical wounds and burns.^16,17

Table 3: Chitosan films and their applications

Chitosan hydrogels are three-dimensional, crosslinked polymer networks, which is formed by hydrating chitosan in aqueous solutions, capable of absorbing and retaining large amounts of water while maintaining their structural integrity. These hydrogels combine the intrinsic bioactivity of chitosan with the beneficial properties of hydrogel systems, making them highly suitable for wound healing applications.

The high-water content of chitosan hydrogels provides a moist wound environment that promotes faster wound healing, reduces dehydration and pain, and promotes cellular functions such as migration and proliferation. The soft, elastic nature of chitosan hydrogel mimics the native extracellular matrix, providing an ideal scaffold for tissue regeneration.

Table 4: Chitosan hydrogels and their applications

Chitosan based nanostructures like nanoparticles and nanofibers have emerged as an advanced platform for wound healing owing to their large surface area, tunable physiochemical properties, ability to deliver bioactive components in a controlled manner. Chitosan nanoparticles are synthesized by ionic gelation, emulsion crosslinking or self-assembly, resulting in nanocarriers with excellent drug entrapment efficiency and controlled release properties. Chitosan nanoparticles have positive surface charge which can adhere to negatively charged bio-membranes, thereby enhancing cellular uptake and interaction with wound bed. Chitosan nanofibers are formulated via electrospinning, producing a fibrous mat that closely mimic natural extracellular matrix structure. These nanofibers exhibit high porosity and surface area, moisture retention as well as customizable, therefore enhance re-epithelization, angiogenesis and collagen deposition. This makes them promising candidates for advanced wound care.

Table 5: Chitosan nanoparticles and nanofibers and their applications

To enhance ease of application, patient comfort, and effectiveness in treating complex or irregular wound geometries, sprayable and injectable chitosan-based formulations have gained increasing attention in modern wound care.

Sprayable chitosan systems are typically low-viscosity solutions or dispersions that can be applied directly to wounds using aerosol or pump-spray devices. Upon contact with the wound, these formulations form a thin film or gel, creating a conformal and protective barrier over the injured area. Sprayable chitosan dressings are particularly beneficial in first-aid and field settings, where fast and sterile wound coverage is essential.

Injectable chitosan formulations are typically in situ forming hydrogels or gels, designed to be delivered via syringe and solidify upon contact with the wound site through temperature, pH, or ionic triggers. These systems are especially useful for deep wounds, tunnelling wounds, or post-surgical cavities where conventional dressings are impractical.

These advanced formulations expand the versatility of chitosan in clinical wound care, offering targeted, patient-friendly solutions for both acute and chronic wounds.^37,38

CHALLENGES

Despite the significant progress in developing chitosan-based wound healing formulations, several challenges have to be addressed to fully utilize their clinical potential.

1. Variability in Raw Material and Processing

Chitosan is typically derived from crustacean shells, and its physicochemical properties like molecular weight and degree of deacetylation can vary significantly depending upon the source and method of extraction. These variations can affect the solubility, bioactivity, and consistency in formulation performance.⁴¹

2. Lack of Standardization and Regulatory Hurdles

There is a need for standard protocols in the preparation, characterization, and quality control of chitosan-based products. Additionally, regulatory approval processes for biomaterials can be complex and time-consuming, especially for novel or composite systems.

3. Limited Clinical Studies

While preclinical results are promising, there remains a gap in large-scale, controlled clinical trials that validate the efficacy and safety of chitosan-based dressings across different wound types and patient populations.

4. Mechanical and Stability Limitations

Native chitosan films and hydrogels often have weak mechanical strength and may degrade quickly in moist environments. Blending with other polymers or crosslinking agents can address this, but this can introduce biocompatibility concerns.³⁶

5. Drug Loading and Release Challenges

While chitosan can encapsulate a variety of therapeutic agents, achieving sustained and targeted drug release without compromising the structural integrity of the dressing remains as a challenge⁴¹

FUTURE PERSPECTIVES

1. Advanced Formulation Techniques

Innovations such as stimuli-responsive hydrogels, 3D-printed scaffolds, electrospun nanofibers, and smart dressings incorporating biosensors or nanocarriers can significantly enhance the functionality and responsiveness of chitosan-based wound care systems.³⁶

2. Personalized and Regenerative Wound Therapies

Integration of stem cells, exosomes, or growth factor delivery systems into chitosan-based matrices holds promise for next-generation regenerative wound therapies for personalised medicines.

3. Sustainable and Scalable Manufacturing

Developing eco-friendly, cost-effective, and scalable production methods for medical-grade chitosan will be crucial for commercial viability and broader clinical utilization.

4. Combination Therapies

Future research may focus on multifunctional composites, such as chitosan combined with silver nanoparticles, antimicrobial peptides, herbal extracts, or synthetic polymers, to enhance therapeutic outcomes through synergistic effects.

5. Regulatory Framework Development

Establishing clearer guidelines and standards for the classification, testing, and approval of chitosan-based medical products will facilitate smoother clinical translation and commercialization

INNOVATION OPPORTUNITIES

The unique physicochemical and biological properties of chitosan present numerous innovation opportunities for the development of next-generation wound healing systems. Advances in material science, nanotechnology, and biomedical engineering can be harnessed to expand the therapeutic functionality and clinical applicability of chitosan-based formulations.

1. Smart and Responsive Wound Dressings

Chitosan can be integrated into stimuli-responsive systems that responds to environmental changes such as pH, temperature, moisture, or bacterial load. These smart dressings release therapeutic agents on-demand or signal wound status through colour changes or embedded biosensors, enabling real-time wound monitoring as well as personalized treatment.

2. 3D Printing and Bio-fabrication

The use of 3D bioprinting to fabricate chitosan-based scaffolds tailored to the specific geometry and depth of a wound provides a great potential for patient-specific wound management. These structures can be loaded with cells, growth factors, or drugs, creating a customizable scaffold for regenerative medicine.

3. Nanotechnology-Enhanced Delivery Systems

Combining chitosan with nanoparticles, liposomes, micelles, or solid lipid carriers enables accurate control over drug release kinetics, improves solubility of poorly water-soluble drugs, and enhances penetration of therapeutic molecule into the wound tissue. Targeted drug delivery systems using chitosan's mucoadhesive and electrostatic properties can decrease dosing frequency and systemic toxicity.

4. Hybrid and Composite Materials

Blending chitosan with other natural (e.g., alginate, gelatin, collagen) or synthetic polymers (e.g., Poly caprolactone, PEG, PLGA) can overcome mechanical barriers while introducing new functionalities. For instance, composite membranes or nanofiber mats can provide enhanced tensile strength, elasticity, and sustained release profiles, suitable for dynamic wound environments.³⁶

5. Integration with Regenerative Therapies

Chitosan serves as a top-notch scaffold for the delivery of stem cells, exosomes, or tissue-engineered skin substitutes. These regenerative approaches, combined with chitosan’s healing-promoting effects, offer advanced solutions for chronic and non-healing wounds like diabetic ulcers and pressure sores.^42,43

6. Eco-friendly and Sustainable Manufacturing

There is growing interest in green synthesis and biorefinery approaches to produce chitosan from non-traditional sources (ex. fungal or insect chitin) using enzymatic or microbial methods. This enhances sustainability and reduces risk of allergy, paving the way for scalable and ethical production of medical-grade chitosan.

7. Digital Health Integration

Merging of chitosan-based smart dressings with wearable electronics and mobile health platforms can revolutionize wound care by providing continuous monitoring, remote data access, and AI-driven treatment adjustments, improving outcomes as well as reducing healthcare costs.

Figure 4: Innovative opportunities of chitosan