Hybrid thermosensitive-mucoadhesive in situ forming gels for enhanced corneal wound healing effect of L-carnosine

Bone morphogenetic protein 4 thermosensitive hydrogel inhibits corneal neovascularization by repairing corneal epithelial apical junctional complexes

Corneal neovascularization (CNV) is a heavy attribute of blinding disease changes. Existing medications need numerous infusions and have a limited absorption. Investigating novel drugs with safety, efficacy, and convenience is crucial. In this study, we developed a bone morphogenetic protein 4 (BMP4)-loaded poloxamer-oxidized sodium alginate (F127-OSA) thermosensitive hydrogel. The 14 % F127-OSA hydrogel transformed from sol to gel at 31-32 °C, which might extend the application period on the ocular surface. The hydrogel's porous structure and uniform dispersion made it possible for drugs to release gradually. We used a suture-induced rat CNV model to investigate the mechanism of CNV inhibition by hydrogel. We discovered that F127-OSA hydrogel loaded with BMP4 could significantly reduce the length and area of CNV, relieve corneal edema, and stop aberrant epithelial cell proliferation. The hydrogel's efficacy was superior to that of the common solvent group. Additionally, BMP4 thermosensitive hydrogel repaired ultrastructure, including microvilli, intercellular junctions, and damaged apical junctional complexes (AJCs), suggesting a potential mechanism by which the hydrogel prevented CNV formation. In conclusion, our investigation demonstrates that F127-OSA thermosensitive hydrogel loaded with BMP4 can repair corneal epithelial AJCs and is a promising novel medication for the treatment of CNV.

Exploring the Ocular Absorption Pathway of Fasudil Hydrochloride towards Developing a Nanoparticulate Formulation with Improved Performance

Rho-kinase (ROCK) inhibitors represent a new category of anti-glaucoma medications. Among them, Fasudil hydrochloride, a selective ROCK inhibitor, has demonstrated promising outcomes in glaucoma treatment. It works by inhibiting the ROCK pathway, which plays a crucial role in regulating the trabecular meshwork and canal of Schlemm's aqueous humor outflow. This study aims to investigate the ocular absorption pathway of Fasudil hydrochloride and, subsequently, develop a nanoparticle-based delivery system for enhanced corneal absorption. Employing the ionic gelation method and statistical experimental design, the factors influencing chitosan nanoparticle (Cs NP) characteristics and performance were explored. Fasudil in vitro release and ex vivo permeation studies were performed, and Cs NP ocular tolerability and cytotoxicity on human lens epithelial cells were evaluated. Permeation studies on excised bovine eyes revealed significantly higher Fasudil permeation through the sclera compared to the cornea (370.0 μg/cm2 vs. 96.8 μg/cm2, respectively). The nanoparticle size (144.0 ± 15.6 nm to 835.9 ± 23.4 nm) and entrapment efficiency range achieved (17.2% to 41.4%) were predominantly influenced by chitosan quantity. Cs NPs showed a substantial improvement in the permeation of Fasudil via the cornea, along with slower release compared to the Fasudil aqueous solution. The results from the Hen's Egg Test Chorioallantoic Membrane (HET-CAM) and Bovine Corneal Opacity and Permeability (BCOP) tests indicated good conjunctival and corneal biocompatibility of the formulated chitosan nanoparticles, respectively. Lens epithelial cells displayed excellent tolerance to low concentrations of these nanoparticles (>94% cell viability). To the best of our knowledge, this is the first report on the ocular absorption pathway of topically applied Fasudil hydrochloride where the cornea has been identified as a potential barrier that could be overcome using Cs NPs.

Advanced biomaterial agent from chitosan/poloxamer 407-based thermosensitive hydrogen containing biosynthesized silver nanoparticles using Eucalyptus camaldulensis leaf extract

CONTEXT

The emergence of multidrug-resistant (MDR) pathogens poses a significant challenge for global public health systems, increasing hospital morbidity and mortality and prolonged hospitalization.

OBJECTIVE

We evaluated the antimicrobial activity of a thermosensitive hydrogel containing bio-synthesized silver nanoparticles (bio-AgNPs) based on chitosan/poloxamer 407 using a leaf extract of Eucalyptus calmadulensis.

RESULTS

The thermosensitive hydrogel was prepared by a cold method after mixing the ingredients and left at 4°C overnight to ensure the complete solubilization of poloxamer 407. The stability of the hydrogel formulation was evaluated at room temperature for 3 months, and the absorption peak (420 nm) of the NPs remained unchanged. The hydrogel formulation demonstrated rapid gelation under physiological conditions, excellent water retention (85%), and broad-spectrum antimicrobial activity against MDR clinical isolates and ATCC strains. In this regard, minimum inhibitory concentration and minimum microbial concentration values of the bio-AgNPs ranged from 2-8 μg/mL to 8-128 μg/mL, respectively. Formulation at concentrations <64 μg/mL showed no cytotoxic effect on human-derived macrophages (THP-1 cells) with no induction of inflammation.

CONCLUSIONS

The formulated hydrogel could be used in biomedical applications as it possesses a broad antimicrobial spectrum and anti-inflammatory properties without toxic effects on human cells.

Novel Sprayable Thermosensitive Benzydamine Hydrogels for Topical Application: Development, Characterization, and In Vitro Biological Activities

Benzydamine hydrochloride (BZD) having analgesic, anesthetic, and anti-inflammatory effects is used orally or topically in the treatment of disorders such as joint inflammation and muscle pain. Within the scope of this study, sprayable thermosensitive BZD hydrogels were developed using thermoresponsive poloxamers to avoid systemic side effects and to provide better compliance for topical administration. Also, hydroxypropyl methyl cellulose (HPMC) was employed to improve the mechanical strength and bioadhesive properties of the hydrogel. The addition of BZD generally decreased the viscosity of the formulations (p < 0.05), while increasing the gelation temperature (p < 0.05). The formulations that did not have any clogs or leaks in the nozzle of the bottle during the spraying process were considered lead formulations. To spray the formulations easily, it was found that the viscosity at RT should be less than 200 mPa·s, and their gelation temperature should be between 26 and 34°C. Increasing HPMC and poloxamer improved bioadhesion. The amount of HPMC and poloxamers did not cause a significant change in the release characteristics of the formulations (p > 0.05); the release profiles of BZD from the formulations were similar according to model-independent kinetic (f2 > 50). HPMC and poloxamers had important roles in the accumulation of BZD in the skin. In vitro biological activity studies demonstrated that the formulations presented their anti-inflammatory activity with TNF-α inhibition but did not have any effect on the inhibition of COX enzymes as expected. As a result, thermosensitive hydrogels containing BZD might be an appropriate alternative, providing an advantage in terms of easier application compared to conventional gels.

Curcumin Transferosome-Loaded Thermosensitive Intranasal in situ Gel as Prospective Antiviral Therapy for SARS-Cov-2

Purpose

Immunomodulatory and broad-spectrum antiviral activities have motivated the evaluation of curcumin for Coronavirus infection 2019 (COVID-19) management. Inadequate bioavailability is the main impediment to the therapeutic effects of oral Cur. This study aimed to develop an optimal curcumin transferosome-loaded thermosensitive in situ gel to improve its delivery to the lungs.

Methods

Transferosomes were developed by using 33 screening layouts. The phospholipid concentration as well as the concentration and type of surfactant were considered independent variables. The entrapment efficiency (EE%), size, surface charge, and polydispersity index (PDI) were regarded as dependent factors. A cold technique was employed to develop thermosensitive in-situ gels. Optimized transferosomes were loaded onto the selected gels. The produced gel was assessed based on shape attributes, ex vivo permeability enhancement, and the safety of the nasal mucosa. The in vitro cytotoxicity, antiviral cytopathic effect, and plaque assay (CV/CPE/Plaque activity), and in vivo performance were evaluated after intranasal administration in experimental rabbits.

Results

The optimized preparation displayed a particle size of 664.3 ± 69.3 nm, EE% of 82.8 ± 0.02%, ZP of -11.23 ± 2.5 mV, and PDI of 0.6 ± 0.03. The in vitro curcumin release from the optimized transferosomal gel was markedly improved compared with that of the free drug-loaded gel. An ex vivo permeation study revealed a significant improvement (2.58-fold) in drug permeability across nasal tissues of sheep. Histopathological screening confirmed the safety of these preparations. This formulation showed high antiviral activity against SARS-CoV-2 at reduced concentrations. High relative bioavailability (226.45%) was attained after the formula intranasally administered to rabbits compared to the free drug in-situ gel. The curcumin transferosome gel displayed a relatively high lung accumulation after intranasal administration.

Conclusion

This study provides a promising formulation for the antiviral treatment of COVID-19 patients, which can be evaluated further in preclinical and clinical studies.

Chitosan/Solid-Lipid Nanoparticles Hybrid Gels for Vaginal Delivery of Estradiol for Management of Vaginal Menopausal Symptoms

Hormonal replacement therapy is the mainstay treatment to improve quality of life and reduce mortality. With the increasing number of young women with early menopause, women now live longer (increased life expectancy). However, poor patient compliance with oral estrogen therapy has emerged. Intravaginal estrogen therapy can provide significant benefits with minimal risk for postmenopausal women with symptoms of the lower urinary tract and vaginal area but who do not want to take oral estrogen. In this study, estradiol-loaded solid lipid nanoparticles (SLPs) were prepared from compritol ATO 888 and precirol ATO 5, and two different stabilizers (Pluronic F127 and Tween 80) were studied. Selected SLPs (F3 and F6) were coated with different concentrations of the mucoadhesive and sustained-release polymer chitosan. Furthermore, gelation time, viscosity, mucoadhesion, ex vivo permeation, and in vitro irritation for vaginal irritation were studied. Particle sizes ranged between 450-850 nm, and EE% recorded 50-83% for the six SLPs depending on the type and amount of lipids used. Cumulative % drug release was significantly enhanced and was recorded at 51% to 83%, compared to that (less than 20%) for the control suspension of estradiol. Furthermore, extensive thermal gelation and mucoadhesion were recorded for chitosan-coated SLPs. Up to 2.2-fold increases in the permeation parameters for SLPs gels compared to the control suspension gel were recorded, revealing a slight to moderate irritation on Hela cell lines. These findings demonstrated chitosan-coated estradiol SLPs as novel and promising vaginal mucoadhesive hybrid nanogels.

Propranolol-Loaded Limonene-Based Microemulsion Thermo-Responsive Mucoadhesive Nasal Nanogel: Design, In Vitro Assessment, Ex Vivo Permeation, and Brain Biodistribution

Propranolol is the first-line drug for managing migraine attacks. D-limonene is a citrus oil known for its neuroprotective mechanism. Thus, the current work aims to design a thermo-responsive intranasal limonene-based microemulsion mucoadhesive nanogel to improve propranolol efficacy. Microemulsion was fabricated using limonene and Gelucire^® as the oily phase, Labrasol^®, Labrafil^®, and deionized water as the aqueous phase, and was characterized regarding its physicochemical features. The microemulsion was loaded in thermo-responsive nanogel and evaluated regarding its physical and chemical properties, in vitro release, and ex vivo permeability through sheep nasal tissues. Its safety profile was assessed via histopathological examination, and its capability to deliver propranolol effectively to rats' brains was examined using brain biodistribution analysis. Limonene-based microemulsion was of 133.7 ± 0.513 nm diametric size with unimodal size distribution and spheroidal shape. The nanogel showed ideal characteristics with good mucoadhesive properties and in vitro controlled release with 1.43-fold enhancement in ex vivo nasal permeability compared with the control gel. Furthermore, it displayed a safe profile as elucidated by the nasal histopathological features. The nanogel was able to improve propranolol brain availability with C_max 970.3 ± 43.94 ng/g significantly higher than the control group (277.7 ± 29.71 ng/g) and with 382.4 % relative central availability, which confirms its potential for migraine management.

Preparation, thermal response mechanisms and biomedical applications of thermosensitive hydrogels for drug delivery

INTRODUCTION

Drug treatment is one of the main ways of coping with disease today. For the disadvantages of drug management, thermosensitive hydrogel is used as a countermeasure, which can realize the simple sustained release of drugs and the controlled release of drugs in complex physiological environments.

AREAS COVERED

This paper talks about thermosensitive hydrogels that can be used as drug carriers. The common preparation materials, material forms, thermal response mechanisms, characteristics of thermosensitive hydrogels for drug release and main disease treatment applications are reviewed.

EXPERT OPINION

When thermosensitive hydrogels are used as drug loading and delivery platforms, desired drug release patterns and release profiles can be tailored by selecting raw materials, thermal response mechanisms, and material forms. The properties of hydrogels prepared from synthetic polymers will be more stable than natural polymers. Integrating multiple thermosensitive mechanisms or different kinds of thermosensitive mechanisms on the same hydrogel is expected to realize the spatiotemporal differential delivery of multiple drugs under temperature stimulation. The industrial transformation of thermosensitive hydrogels as drug delivery platforms needs to meet some important conditions.

Cell-instructive biomaterials in tissue engineering and regenerative medicine

The field of biomaterials aims to improve regenerative outcomes or scientific understanding for a wide range of tissue types and ailments. Biomaterials can be fabricated from natural or synthetic sources and display a plethora of mechanical, electrical, and geometrical properties dependent on their desired application. To date, most biomaterial systems designed for eventual translation to the clinic rely on soluble signaling moieties, such as growth factors, to elicit a specific cellular response. However, these soluble factors are often limited by high cost, convoluted synthesis, low stability, and difficulty in regulation, making the translation of these biomaterials systems to clinical or commercial applications a long and arduous process. In response to this, significant effort has been dedicated to researching cell-directive biomaterials which can signal for specific cell behavior in the absence of soluble factors. Cells of all tissue types have been shown to be innately in tune with their microenvironment, which is a biological phenomenon that can be exploited by researchers to design materials that direct cell behavior based on their intrinsic characteristics. This review will focus on recent developments in biomaterials that direct cell behavior using biomaterial properties such as charge, peptide presentation, and micro- or nano-geometry. These next generation biomaterials could offer significant strides in the development of clinically relevant medical devices which improve our understanding of the cellular microenvironment and enhance patient care in a variety of ailments.

Thermoresponsive mucoadhesive hybrid gels in advanced drug delivery systems

Thermoresponsive polymers have seen extensive use in the development of stimuli-responsive drug formulations for oral, buccal, nasal, ocular, topical, rectal, parenteral, and vaginal routes of administration. Despite their great potential, their use has been limited by various obstacles, such as undesirable high polymer concentration, wide gelation temperature, low gel strength, poor mucoadhesiveness, and short retention. Mucoadhesive polymers have been suggested to improve the mucoadhesive features of thermoresponsive gels, leading to increased drug bioavailability and efficacy. This article highlights the use of in-situ thermoresponsive mucoadhesive hydrogel blends or hybrids that have been developed and assessed in various routes of administration.

Thermosensitive and mucoadhesive hydrogel containing curcumin-loaded lipid-core nanocapsules coated with chitosan for the treatment of oral squamous cell carcinoma

Buccal drug administration may be chosen as a medication route to treat various diseases for local or systemic effects. This study proposes the development of a thermosensitive hydrogel containing curcumin-loaded lipid-core nanocapsules coated with chitosan to increase mucoadhesion, circumventing several limitations of this route of administration. Hydroxypropylmethylcellulose and Poloxamer^® 407 were incorporated for hydrogel production. Physicochemical characterization parameters, such as particle size distribution, mean diameter, polydispersity index, zeta potential, and morphology, were analyzed. Spherical homogeneous particles were obtained with average diameter, of 173 ± 22 nm for LNCc (curcumin lipid-core nanocapsules) and 179 ± 48 nm for CLNCc (chitosan-curcumin lipid-core nanocapsules). A PDI equal to 0.09 ± 0.02 for LNCc and 0.26 ± 0.01 for CLNCc confirmed homogeneity. Tensile analysis and washability test on porcine buccal mucosa indicated higher mucoadhesion for hydrogels in comparison to the nanocapsules in suspension, remaining on the mucous membrane up to 8 h (10.92 ± 3.95 µg of curcumin washed for H-LNCc and 28.41 ± 24.47 µg for H-CLNCc) versus the latter, which remained washed on the membrane for 90 min only (62.60 ± 4.72 µg for LNCc and 52.08 ± 1.63 µg for CLNCc). The irritant potential (IR) of the formulations was evaluated by the hen's egg chorioallantoic membrane test (HET-CAM), with no irritation phenomena observed. Formulations were tested for their efficacy in an in vitro model against oral squamous cancer cell line, showing a significant reduction in cell viability on all tested groups. These findings demonstrated that the proposed nanosystem is mucoadhesive and has potential to deliver buccal treatments.

Thermoresponsive in-situ gel containing hyaluronic acid and indomethacin for the treatment of corneal chemical burn

Ocular chemical burns are prevalent injuries that must have immediate and effective treatment to avoid complications. Aiming to improve bioavailability and efficacy, a poloxamer-based thermoresponsive in-situ gelling system containing hyaluronic acid and indomethacin was developed. Formulations with different polymeric proportions were screened through rheological measurements resulting in an optimized system (F2) with gelling temperature of 34.2 ± 0.11 °C. Its maximum viscosity varied from 77.33 mPa (25 °C) to 82.95 mPa (34 °C) following a non-Newtonian profile and a pH of 6.86 ± 0.01. No incompatibilities were found after infrared analysis. Polarized light microscopy and cryo-transmission electron microscopy have demonstrated micelles of nano-sized dimensions (21.86 nm) with indomethacin entrapped in the core, forming a polymeric network under heating. In vitro tests revealed a cumulative release of 59.75 ± 3.17 % up to 24 h under a sustained release profile. Results from HET-CAM assay indicated that F2 was well tolerated. Corneal wound healing was significantly faster in animals treated with F2 compared to a commercial formulation and an untreated group. These findings suggests that F2 could be an efficient system to delivery drugs into the ocular surface improving wound healing.

Concentration-Dependent Antibacterial Activity of Chitosan on Lactobacillus plantarum

The antimicrobial effect of chitosan and synthetic chitosan derivatives has been confirmed on many Gram-positive and Gram-negative bacteria and fungi. The tests were carried out on pathogenic microorganisms, so the mechanism and concentration dependence of the inhibitory effect of chitosan were revealed. We conducted our tests on a probiotic strain, Lactobacillus plantarum. Commercially available chitosan derivatives of different molecular weights were added to L. plantarum suspension in increasing concentrations. The minimum inhibitory concentration (MIC) value of chitosan was determined and confirmed the viability decreasing effect at concentrations above the MIC with a time-kill assay. The release of bacterium cell content was measured at 260 nm after treatment with 0.001-0.1% concentration chitosan solution. An increase in the permeability of the cell membrane was observed only with the 0.1% treatment. The interaction was also investigated by zeta potential measurement, and the irreversible interaction and concentration dependence were established in all concentrations. The interaction of fluorescein isothiocyanate (FITC) labeled low molecular weight chitosan and bacterial cells labeled with membrane dye (FM^® 4-64) was confirmed by confocal microscopy. In conclusion, the inhibitory effect of chitosan was verified on a probiotic strain, which is an undesirable effect in probiotic preparations containing chitosan additives, while the inhibitory effect experienced with pathogenic strains is beneficial.

Quercetin Loaded Cationic Solid Lipid Nanoparticles in a Mucoadhesive In Situ Gel-A Novel Intravesical Therapy Tackling Bladder Cancer

The study aim was to develop an intravesical delivery system of quercetin for bladder cancer management in order to improve drug efficacy, attain a controlled release profile and extend the residence time inside the bladder. Either uncoated or chitosan coated quercetin-loaded solid lipid nanoparticles (SLNs) were prepared and evaluated in terms of colloidal, morphological and thermal characteristics. Drug encapsulation efficiency and its release behaviour were assessed. Furthermore, cytotoxicity of SLNs on T-24 cells was evaluated. Ex vivo studies were carried out using bovine bladder mucosa. Spherical SLNs (≈250 nm) ensured good entrapment efficiencies (EE > 97%) and sustained drug release up to 142 h. Cytotoxicity profile revealed concentration-dependent toxicity recording an IC50 in the range of 1.6−8.9 μg/mL quercetin. SLNs were further dispersed in in situ hydrogels comprising poloxamer 407 (20%) with mucoadhesive polymers. In situ gels exhibited acceptable gelation temperatures (around 25 °C) and long erosion time (24−27 h). SLNs loaded gels displayed remarkably enhanced retention on bladder tissues relative to SLNs dispersions. Coated SLNs exhibited better penetration abilities compared to uncoated ones, while coated SLNs dispersed in gel (G10C-St-QCT-SLNs-2) showed the highest penetration up to 350 μm. Hence, G10C-St-QCT-SLNs-2 could be considered as a platform for intravesical quercetin delivery.

Opportunities and Challenges of Switchable Materials for Pharmaceutical Use

Switchable polymeric materials, which can respond to triggering signals through changes in their properties, have become a major research focus for parenteral controlled delivery systems. They may enable externally induced drug release or delivery that is adaptive to in vivo stimuli. Despite the promise of new functionalities using switchable materials, several of these concepts may need to face challenges associated with clinical use. Accordingly, this review provides an overview of various types of switchable polymers responsive to different types of stimuli and addresses opportunities and challenges that may arise from their application in biomedicine.

Microemulsions as Lipid Nanosystems Loaded into Thermoresponsive In Situ Microgels for Local Ocular Delivery of Prednisolone

This study aimed to develop and evaluate thermoresponsive in situ microgels for the local ocular delivery of prednisolone (PRD) (PRD microgels) to improve drug bioavailability and prolong ocular drug residence time. Lipid nanosystems of PRD microemulsions (PRD-MEs) were prepared and evaluated at a drug concentration of 0.25-0.75%. PRD microgels were prepared by incorporating PRD-MEs into 10 and 12% Pluronic^® F127 (F127) or combinations of 12% F127 and 1-10% Kolliphor^®P188 (F68). PRD microgels were characterized for physicochemical, rheological, and mucoadhesive properties, eye irritation, and stability. Results showed that PRD-MEs were clear, miscible, thermodynamically stable, and spherical with droplet size (16.4 ± 2.2 nm), polydispersity index (0.24 ± 0.01), and zeta potential (-21.03 ± 1.24 mV). The PRD microgels were clear with pH (5.37-5.81), surface tension (30.96-38.90 mN/m), size, and zeta potential of mixed polymeric micelles (20.1-23.9 nm and -1.34 to -10.25 mV, respectively), phase transition temperature (25.3-36 °C), and gelation time (1.44-2.47 min). The FTIR spectra revealed chemical compatibility between PRD and microgel components. PRD microgels showed pseudoplastic flow, viscoelastic and mucoadhesive properties, absence of eye irritation, and drug content (99.3 to 106.3%) with a sustained drug release for 16-24 h. Microgels were physicochemically and rheologically stable for three to six months. Therefore, PRD microgels possess potential vehicles for local ocular delivery.

Imatinib Mesylate-Loaded Rosin/Cinnamon Oil-Based In Situ Forming Gel against Colorectal Cancer Cells

Localized delivery systems have been typically designed to enhance drug concentration at a target site and minimize systemic drug toxicity. A rosin/cinnamon oil (CO) in situ forming gel (ISG) was developed for the sustainable delivery of imatinib mesylate (IM) against colorectal cancer cells. CO has been claimed to express a potent anticancer effect against various cancer cells, as well as a synergistic effect with IM on colorectal cancer cells; however, poor aqueous solubility limits its application. The effect of rosin with the adding CO was assessed on physicochemical properties and in vitro drug release from developed IM-loaded rosin/CO-based ISG. Moreover, in vitro cytotoxicity tests were conducted against two colorectal cancer cells. All formulations exhibited Newtonian flow behavior with viscosity less than 266.9 cP with easier injectability. The adding of CO decreased the hardness and increased the adhesive force of the obtained rosin gel. The gel formation increased over time under microscopic observation. CO-added ISG had a particle-like gel appearance, and it promoted a higher release of IM over a period of 28 days. All tested ISG formulations revealed cytotoxicity against HCT-116 and HT-29 cell lines at different incubation times. Thus, CO-loaded rosin-based ISG can act as a potentially sustainable IM delivery system for chemotherapy against colorectal cancer cells.

Applications of Chitosan in Surgical and Post-Surgical Materials

The continuous advances in surgical procedures require continuous research regarding materials with surgical applications. Biopolymers are widely studied since they usually provide a biocompatible, biodegradable, and non-toxic material. Among them, chitosan is a promising material for the development of formulations and devices with surgical applications due to its intrinsic bacteriostatic, fungistatic, hemostatic, and analgesic properties. A wide range of products has been manufactured with this polymer, including scaffolds, sponges, hydrogels, meshes, membranes, sutures, fibers, and nanoparticles. The growing interest of researchers in the use of chitosan-based materials for tissue regeneration is obvious due to extensive research in the application of chitosan for the regeneration of bone, nervous tissue, cartilage, and soft tissues. Chitosan can serve as a substance for the administration of cell-growth promoters, as well as a support for cellular growth. Another interesting application of chitosan is hemostasis control, with remarkable results in studies comparing the use of chitosan-based dressings with traditional cotton gauzes. In addition, chitosan-based or chitosan-coated surgical materials provide the formulation with antimicrobial activity that has been highly appreciated not only in dressings but also for surgical sutures or meshes.