Swelling Studies Research Articles

Preparation of nanocomposite hydrogel based on Fe3O4-TMSPM/poly(HEMA-PEG6MA-IA) for the removal of methylene blue dye from aqueous solution

In this work, a new hydrogel poly(2-hydroxyethyl methacrylate-co-polyethylene glycol methacrylate-co-itaconic acid) poly(HEMA-PEG6MA-IA) covalently crosslinked with Fe3O4 nanoparticles functionalized with 3-(trimethoxysilyl)propyl methacrylate organosilane (TMSPM) was prepared by free radicals, named Fe3O4-TMSPM/HG. FTIR-ATR, TGA, XRD, and TEM experiments were utilized to explore the Fe3O4-TMSPM/HG nanocomposite hydrogel. Swelling studies were also carried out in water, in different pH media, and then used in the adsorption of the cationic dye methylene blue (MB) from aqueous media. The factors controlling the adsorption process such as pH, dose, contact time, initial MB concentration, and temperature were investigated. The maximum MB adsorption capacity (270.27 mg/g) using Fe3O4-TMSPM/HG was obtained under the best conditions pH 8, dose 0.5 mg/mL, contact time 24 h, and ambient laboratory temperature (≈15 °C). The kinetic and isothermal experiments showed that the adsorption of MB followed the pseudo-second-order and Langmuir models. The effect of temperature on the adsorption capacity is related to the swelling, since the Fe3O4-TMSPM/HG nanocomposite hydrogel exhibit temperature-responsive. After 5 adsorption–desorption cycles, the adsorption decreased by 19 mg/g compared to the initial adsorption capacity. All the experimental results show that the prepared Fe3O4-TMSPM/HG nanocomposite hydrogel has the potential to be applied as an adsorbent for MB dye.

Cinnamon oil value addition in natural rubber latex‐organic peroxide vulcanization system

AbstractNatural rubber is a sustainable material which plays a vital role in a wide variety of applications. Value additions to this natural material enhance its horizons of utilization and encompass multiple advantages. This endeavor focuses on elevating the properties of the natural rubber latex (NRL)‐dicumyl peroxide vulcanization system with the utilization of cinnamon oil (CIN‐OIL). CIN‐OIL was characterized by GCMS, FTIR, and UV–Vis. The FTIR and TGA have confirmed the incorporation of the CIN‐OIL into the NRL. Swelling studies confirmed that the addition of CIN‐OIL has not interfered with the process of peroxy crosslinking. The adhesive peel test and facial tissue test clearly concluded that CIN‐OIL has reduced the initial tackiness of the material which is apparent in peroxy NR vulcanizates. Tear strength and modulus values were increased with CIN‐OIL due to the formation of physical crosslinking. Weathering tests confirmed the higher degradability of the CIN‐OIL‐added NRL samples. Furthermore, films were tested positive for antibacterial activity against both gram‐positive and gram‐negative bacteria. Along with the enhanced degradability, antibacterial activity, reduced initial tackiness, and enhanced mechanical properties, CIN‐OIL in NRL has enriched its qualities.

Influence of physico-chemical properties of hydroxypropyl methylcellulose on quetiapine fumarate release from sustained release matrix tablets

Quetiapine fumarateis a typical antipsychotic with a short half-life of 6 h and is administered multiple times daily. In this study, a copolymer for controlled delivery of quetiapine fumarate will be developed. In order to prevent side effects and improve patient compliance, hydroxypropyl methylcellulose K15M (HPMC K15M) was included in the formulation of the quetiapine fumarate oral sustained-release tablets at a concentration of 10–30%. A series of analytical methods were used to determine the characteristics of the prepared hydrogels, including Fourier transform-infrared spectroscopy, Differential scanning calorimetry, X-ray diffraction, and Scanning electron microscope. At two different pH values (1.2 and 6.8), swelling and release studies were conducted. A variety of release kinetic models was used to study drug release mechanisms. A non-Fickian diffusion mechanism released hydrogels prepared from quetiapine fumarate. It was found that swelling was increased by increasing the amount of HPMC K15M. Compared to the other batches (10–20%), the produced tablets with 30% HPMC K15M content had a better release profile after 20 h of dissolution. Because of the effective matrix complex’s limited solubility in water, the drug diffuses through the gel layer at a steady rate rather than dissolving quickly.

Development and Evaluation of pH‐Responsive Microbeads Incorporated with Nickel Zinc Ferrite Nanoparticles for Controlled Release of Doxorubicin

AbstractThe development of a pH‐responsive, biocompatible polymeric carrier for controlled delivery of bioactive agents holds significant practical value for pharmaceutical applications. In this study, we used the gelation method to make pH‐responsive polymeric microbeads using sodium alginate (SA), poly(vinylpyrrolidone‐co‐vinyl acetate) (PVPVA), and nickel zinc ferrite (NZF) nanoparticles for controlled release of doxorubicin (DOX). The generated microbeads are characterized using various techniques, including Fourier‐transform infrared spectroscopy, X‐ray diffraction, scanning electron microscopy, and transmission electron microscopy. Swelling studies reveal enhanced permeability at pH 6.4, and in vitro release studies demonstrate a higher release rate at pH 6.4 compared to pH 2.0. Cytotoxicity tests on MCF‐7 cells (a type of breast cancer cell line) showed that NZF‐loaded microbeads, especially SP‐NZFNPs‐DOX, were more effective than other carriers, indicating their potential usefulness in cancer treatment. Furthermore, biocompatibility tests demonstrate that the SA/PVPVA microbeads and nanoparticles are biocompatible with 3T3 fibroblasts. This study contributes valuable insights to the evolving landscape of nanotechnology in cancer treatment, emphasizing the synergistic role of NZF nanoparticles, SA, and PVPVA in optimizing drug delivery systems.

Effect of preservation on changes in the volume of corneal endothelial cells in an environment with a high concentration of potassium

The experimental study of preservation length on the effect of high potassium concentration in the medium on the volume of human corneal endothelial cells was done. The results of the study of individual samples of fragments of donor material and the values calculated using joined data after hypothermic preservation for 4 and 10 days are presented. The increase of the time when cornea samples are kept in preservation medium (Eusol-C) at 4℃ led to a decrease in the average value (M ± SEM) of cell swelling indicator (N) in a potassium medium from 1.055 ±0.001; n = 982 to 1.014±0.001; n = 338; after 4 and 10 days, respectively. Student’s-t test for independent samples showed a high degree of significance for the difference between these values (p = 2E-76). Identification of the proportion of cells capable to swell in a medium with a high content of potassium ions (N 1), reflecting the electrogenic activity in these cells, showed a decrease of this indicator in the studied groups with increasing duration of preservation (94.3% and 56.8% after 4 and 10 days, respectively). Based on the results of the study, it is suggested that the values of endothelial cells swelling in a potassium environment can serve as indicators of the cells’ ability to restore electrogenic transport. It is concluded that the study of cell swelling in a medium with a high content of potassium ions can provide information for predicting the functionality of the graft.

Preparation, Swelling, and Drug Release Studies of Chitosan-based Hydrogels for Controlled Delivery of Buspirone Hydrochloride.

Buspirone is used for the management of depression and anxiety disorders. Due to its short half-life and low bioavailability, it requires multiple daily doses and is associated with some side effects. This study aimed to develop chitosan-based hydrogels as drug-controlled release carriers. The objective of this study is to prepare chitosan-based hydrogels as controlled release carriers in order to overcome the side effects of buspirone HCl and improve patients' compliance and their life quality. Polymer chitosan was polymerized with two monomers, acrylic acid and itaconic acid, to synthesize pH-sensitive hydrogel. The Fourier transform infrared spectroscopy (FTIR), thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC) analysis were performed to confirm the structure formation and thermal stability. Water penetration capability and loading of the drug were performed by porosity and drug loading studies. The swelling and dissolution tests were performed to analyze the pH-sensitive nature of the developed hydrogels. FTIR, TGA, and DSC demonstrated that the chitosan-based hydrogels were successfully prepared. An increase in water penetration and drug loading into the hydrogel network was seen with the high incorporation of chitosan, acrylic acid, and itaconic acid. The swelling and dissolution studies revealed that prepared hydrogel offered the greatest swelling and drug release at a high pH of 7.4. The swelling and drug release from the hydrogel were affected by the concentrations of the incorporated contents. A controlled release of the drug was achieved by using chitosan-based hydrogel as a delivery carrier compared to commercial tablets of buspirone. The results showed that the developed chitosan-based hydrogel can be considered one of the most suitable drug carrier systems for the controlled delivery of buspirone.

Evaluation of polymer combinations in vaginal mucoadhesive tablets for the extended release of acyclovir

Genital herpes, caused by herpes simplex virus type 2 (HSV-2), affects nearly 500 million people, mostly women. Since the main route of transmission is sexual contact, the development of an acyclovir extended-release vaginal microbicide would be a suitable tool for the prevention of virus transmission. In this work, we evaluated the potential of three polymers with different characteristics (chitosan, xanthan gum and ethyl cellulose) for obtaining acyclovir extended-release vaginal tablets. By combining the polymers, certain useful synergies were observed to modify their mucoadhesive capacity and control drug release. In the swelling studies, it observed that a polyelectrolyte complex with more moderate swelling and sustained gelation was formed between chitosan and xanthan gum exclusively in acidic medium (simulated vaginal fluid). This complex allowed prolonging the mucoadhesion of the tablets in ex vivo studies performed with vaginal mucosa, which would translate into better retention in the vagina after administration. In addition, the combination of chitosan and xanthan gum allowed obtaining a controlled release of acyclovir for 5 days, regardless of the pH of the medium, which would guarantee that drug release continues even in the presence of seminal fluid.

Evaluating the Impact of Green Coffee Bean Powder on the Quality of Whole Wheat Bread: A Comprehensive Analysis.

The current investigation focuses on the effect of different concentrations of green coffee bean powder (GCBp) on the physicochemical, microbiological, and sensory characteristics of whole wheat bread (WWB). C1 bread formulation (containing 1% GCBp) exhibited the highest loaf volume, suggesting optimal fermentation. Moisture analysis revealed minor alterations in the moisture retention attributes of the bread formulations. Impedance analysis suggested that C1 exhibited the highest impedance with a high degree of material homogeneity. Swelling studies suggested similar swelling properties, except C5 (containing 5% GCBp), which showed the lowest swelling percentage. Furthermore, color and microcolor analysis revealed the highest L* and WI in C1. Conversely, higher concentrations of GCBp reduced the color attributes in other GCBp-containing formulations. FTIR study demonstrated an improved intermolecular interaction in C1 and C2 (containing 2% GCBp) among all. No significant variation in the overall textural parameters was observed in GCBp-introduced formulations, except C2, which showed an improved gumminess. Moreover, the TPC (total phenolic content) and microbial analysis revealed enhanced antioxidant and antimicrobial properties in GCBp-incorporated formulations compared to Control (C0, without GCBp). The sensory evaluation showed an enhanced appearance and aroma in C1 compared to others. In short, C1 showed better physicochemical, biological, and sensory properties than the other formulations.

Elastomeric Ionic Hydrogel-Based Flexible Moisture-Electric Generator for Next-Generation Wearable Electronics.

Rapid consumption of traditional energy resources creates utmost research interest in developing self-sufficient electrical devices to progress next-generation electronics to a level up. To address the global energy crisis, moisture-electric generators (MEGs) are proving to be an emerging technology in this field, capable of powering wearable electronics by harvesting energy from abundantly available ambient moisture without any requirement for external/additional energy. Recent advances in MEGs generally utilize an inorganic, metal, or petroleum-based polymeric material as an active material, which may produce sufficient current but lacks the flexibility and stretchability required for wearable electronics. Herein, we prepared an elastomer-based ionic hydrogel as an active material, and an MEG was fabricated by placing the ionic hydrogel on a PET sheet with two copper tapes on both sides of the hydrogel. The preparation of the hydrogel was thoroughly optimized and characterized in terms of spectroscopic analysis, swelling, water retention, and mechanical and rheological studies. The highly stretchable (350%) fabricated MEG is capable of producing a short-circuit current (JSC) of 16.1 μA/cm2, an open-circuit voltage (VOC) of 0.24 V, and a power density of 3.86 μW/cm2. The synergistic effect of the ion concentration gradient and the redox reaction on electrodes can be considered MEG's working principle. Apart from the current generation, this device is also used as a self-powered electronic sensor to monitor different physical activities by measuring breathing patterns. This prepared device is also capable of sensing the proximity of a hand. Therefore, our low-cost, easily fabricable, sustainable MEG device can be a potential aspirant for next-generation self-powered wearable electronics in healthcare applications.

Removal of copper and cobalt ions from aqueous solutions using starch‐xanthate based novel smart hydrogel via adsorption technique: Swelling, adsorption isotherm, and kinetic study

AbstractThe concentration of harmful metal ions is growing globally, which raises the risk to both human and ecological health. The use of “adsorption” technique has been found to be very effective, for the removal of toxic metal ions. Among other things, hydrogels as an adsorbent work effectively for the removal of toxic metal ions and other aquatic pollutants. The newly designed potato starch‐xanthate (SX) based hydrogel (SX‐modified hydrogel) has been synthesized using a mixture of acrylamide (AAm) and acrylic acid (AA) monomers, with the help of free‐radical graft copolymerization technique. The synthesized SX‐modified hydrogel has been characterized by several analytical techniques, namely, UV–visible (UV–vis) spectroscopy, Fourier transform infrared (FTIR) spectroscopy, gel permeation chromatography (GPC), thermogravimetric (TG) analysis, point of zero charge (ΔpHPZC) analysis, x‐ray diffraction (XRD) analysis, and scanning electron microscope (SEM) analysis. The main objective of the current work is to remove the Cu2+ and Co2+ ions from wastewater using SX‐modified hydrogel as well as to study the swelling and water retention properties of the SX‐modified hydrogel. The swelling ratio of SX‐modified hydrogel has been found to be 312.31, 374.01, and 410.20 g/g at optimum pH 10, temperature 35°C, time 675 min in gray wastewater, tap water, and distilled water, respectively. The maximum percentage removal of Cu2+ and Co2+ ions by SX‐modified hydrogel has been found as 97.7% and 94.2%, respectively, at optimum conditions. The Langmuir isotherm model fits best with the experimental data, with maximum adsorption capacity of 515.46 mg/g for Cu2+ and 483.09 mg/g for Co2+ ions, respectively. The kinetic studies suggest that the adsorption process is governed by the second order kinetic model with rate constant of 2.06 × 10−4 g/(mg min) for Cu2+ and 1.79 × 10−4 g/(mg min) for Co2+ ions, respectively. The negative ΔG values suggest the adsorption process is spontaneous in nature. In addition, the positive ΔH values support the adsorption process is endothermic in nature. The SX‐modified hydrogel showed a remarkable desorption efficiency with 96.7% for Cu2+ and 92.5% for Co2+ ions and reusability for four consecutive adsorption–desorption cycles. It can be concluded that the SX‐modified hydrogel has showed an effective, economical, easy, low energy consuming, and significant potential in the treatment of wastewater containing heavy metal ions.

Electrophoretically deposited Asphaltum punjabianum (Shilajit) coatings on polyvinylalcohol/carboxymethylcellulose hydrogels

The present study aims to develop Asphaltum punjabianum (namely Shilajit) coated Polyvinyl alcohol (PVA)/Carboxymethyl cellulose (CMC) hydrogels and examine their structural, morphological, degradation, and biological properties. Hydrogels were produced at two different concentrations: 70:30 PVA/CMC and 90:10 PVA/CMC. Following that, Shilajit was applied to the synthesized hydrogels using electrophoretic deposition for a duration of 3 min at 30 V. The scanning electron microscopy images showed that the hydrogel's surface had a regular distribution of irregular Shilajit particles. Fourier transform infrared spectroscopy (FTIR) analysis demonstrated the presence of hydrogen bonding between PVA and CMC hydrogels and Shilajit, indicating the successful deposition of Shilajit on the hydrogel. The hydrogels coated with Shilajit exhibited strong antimicrobial activity, resulting in an inhibition zone measuring 34 mm against Escherichia coli (E. coli) and 41 mm against Staphylococcus aureus (S. aureus). The hydrogels exhibited a cell viability of 80 % with mesenchymal stem cells (MSCs), and the release of collagen II also increased. Furthermore, the PVA/CMC/Shilajit hydrogel exhibited a lower degradation rate compared to the PVA/CMC hydrogel. The results of the swelling, degradation, and drug release studies indicate that the shilajit coating is appropriate for the long-term process of tissue and cartilage regeneration.

3D printed subcutaneous implant for prolonged delivery of tenofovir with desired release capability, biocompatibility, and viability

This study introduced a progressive approach to address the challenges associated with drug delivery in hepatitis B by developing a 3D printed subcutaneous implant. The implant, composed of a polymer-reinforced bovine serum albumin hydrogel crosslinked with glutaraldehyde, exhibited shear thinning and thixotropic behavior. This allows it to undergo transformation into an implant using a semisolid extrusion-based 3D printing technique. Thorough analysis encompassing physical, thermal, and spectroscopy assessments ensured thermal and chemical stability of the implant. Scanning electron microscopy revealed the highly porous microstructures of the hydrogel implant, enhancing its suitability for drug encapsulation. Swelling study showed only 7.88 % swelling of the implant after 28 days, suggesting restricted water movement into the implant matrix, leading to a gradual release of the encapsulated drug. The biodegradable nature of the implant was confirmed using an enzyme degradation study. Notably, the hydrogel implant exhibited sustained release of tenofovir of approximately 63 % over a 28-day period, presenting a promising avenue for prolonged therapeutic interventions in both hepatitis B. Furthermore, the crosslinked hydrogel was found to be cytocompatible in human kidney and dermal fibroblast cells. Overall, this work signifies a notable advancement in implantable drug delivery systems utilizing both hydrogel and the emerging 3D printing technique, offering a potential solution for sustained and localized treatment of chronic viral infections.

Experimentation, identification, and simulation of polymer swelling at extrusion die outlets

AbstractThe behavior of polyamide PA12 melt extrudates at die outlets is modeled to determine swelling process and rate. It is assessed as a function of imposed input parameters, process parameters, and die geometries. The modeling is carried out using Comsol Multiphysics® platform to simulate the swelling; in particular, its progression in time is investigated for different extrusion process parameters. The experimental swelling observed in extrusion lines tests is compared with the Tanner and Carreau‐Yasuda rheological models. A database is built up with all experiments carried out; the comparison between numerical and experimental results shows close agreement. A parametric analysis of the experimental and numerical swelling is performed. It confirms the important role of the die diameter on swelling rate, independently of shear rate. Increase in temperature lowers swelling rate at constant shear rates and geometric aspect ratio of the dies.Highlights Experimental and numerical study of polymer swelling at capillary die outlets. Behavior of PA12 polymer extrudate modeled to determine its swelling. Rheological models implemented to simulate the swelling phenomenon. Simulation results validated with experimental tests for two millimetric dies. Influence of die geometrical parameters investigated and justified.

Cure, Mechanical, Swelling, Antimicrobial and Biodegradability Studies of Biocomposites of Acrylonitrile Butadiene Rubber and Chitosan

Cure, Mechanical, Swelling, Antimicrobial and Biodegradability Studies of Biocomposites of Acrylonitrile Butadiene Rubber and Chitosan

Development of High-Efficiency Fertilizer by Hydrogels Obtained from Cassava Starch and Citric Acid for Slow Release of Ammonium and Potassium.

Fertilizers with enhanced efficiency or high-efficiency fertilizers increase the nutrient availability, minimize losses, and reduce costs, thereby increasing crop yields and food production while mitigating environmental impacts. This research evaluates the synthesis of biodegradable hydrogels from cassava starch and citric acid for agrochemical applications. Hydrogels were synthesized using water as the solvent and applied for the controlled release of macronutrients (N and K). Four concentrations of nutrient-containing salts were tested (0.5 to 10.0% w/w). Materials were analyzed using ATR-FTIR spectroscopy and swelling studies. The presence of nutrients reduced both the crosslinking efficacy and the water absorption capacity, with the latter dropping from 183.4 ± 0.6% to 117.9 ± 3.7% and 157.4 ± 25.0% for hydrogels loaded with NH4Cl and KCl, respectively. The cumulative release of K and N from the hydrogel was monitored for 144 h and examined using kinetics models, revealing that the releases follow Fickian's diffusion and anomalous diffusion, respectively. Additionally, the material was formed using cassava with peel previously milled to reduce the production costs, and its potential for nutrient-controlled delivery was evaluated, with the finding that this hydrogel decreases the release rate of nitrogen. The results suggest that these biomaterials may have promising applications in the agrochemical industry in the making of high-efficiency fertilizers.

A study of biodegradation, water uptake and thickness swelling of animal fibers reinforced unsaturated polyester resin composites

The ever-increasing quantities of trash produced by the poultry and tannery industries, particularly chicken feathers, cow hairs, and waste leather fibers, pose serious challenges to maintaining a pristine natural environment. In this research, the polymer composites were produced by combining 2, 5, 7, 10, 12, and 15 % (by weight) recycled chicken feather fibers (CFF), cow hair fibers (CHF), and leather fibers (LF) with inorganic materials ZnO, Al2O3, CaCO3, and unsaturated polyester resin (UPR) through a hand lay-up process. After cleaning, a portion of the fibers was subjected to a two-hour soak in 0.20 M KOH at 50 °C, followed by five hours of drying at 60 °C, and the remaining half was not attended. This study successfully reduced environmentally hazardous waste from the poultry and tannery industries. The biodegradation of composites was compared in weather, water, brine, soil and compost over a period of 90 days at 25 °C, suggesting that the composites have potential in a variety of settings. Degradation rates varied among the composites, and the leather fibre-UPR composites (LR + UPR + Al2O3) showed the fastest degradation rate under all media and were especially degraded highest percentages (17.8 %) when buried in compost. Degradation percentages in compost media for (CHF + UPR + Al2O3), (CFF + UPR + Al2O3) and (CHF + CFF + UPR + Al2O3)) composites are 16.3 %, 14.8 %, and 13.5, respectively. The helical structure of the composites disintegrated in thermogravimetric analysis (TGA), losing its chain-linkage skeleton and peptide fiber bridges, and dissolving keratin and collagen into carbon dioxide (CO2), hydrogen sulfide (H2S), and hydrogen cyanide (HCN). The results of the water uptake and thickness swelling study for up to 15 days due to water absorption can have positive effects on the mechanical properties of the composite material and found 8.8 % water uptake and 15.8 % thickness swelling both for (LR + UPR + Al2O3) composite.

Polyurethane dispersion/carboxylated nitrile butadiene rubber blends produced by a greener dual crosslinking approach

A latex blend comprising polyurethane dispersion (PUD) and carboxylated nitrile butadiene rubber (XNBR) in an 80:20 ratio was prepared in the presence of epoxide and organo-modified siloxane crosslinkers. The aim of the study was to enhance the tensile, thermal, and chemical properties of the PUD/XNBR latex blend without the incorporation of sulphur and accelerator. Studies revealed that the combined action of epoxide and organo-modified siloxane crosslinker demonstrated adequate intermolecular hydrogen bonding, thereby resulting in superior tensile strength. Differential scanning calorimetry (DSC) analysis showed alterations in chain orientation and melting enthalpy due to the introduction of two crosslinkers that impart ordered hydrogen bonding to a certain degree. The compactness of the structure of the cure molecule may be closely related to the heating enthalpy, as in the following sequence, PUD80/XNBR20/E1 will have a loosely packed structure, followed by PUD80/XNBR20/E0.5S0.5 and PUD80/XNBR20/S1. Chemical swelling studies revealed the impact of crosslinker combinations on hydrogen bonding (both ordered and disordered), affirming the consequential enhancement in chemical resistance. This study confirms that the attained intermolecular hydrogen bonding results in desirable mechanical and chemical resistance performance, making the latex blend suitable for glove applications.

Ranula– A case report and literature review

Ranula, a salivary gland disorder, manifests as a cystic swelling on the floor of the mouth and can arise from various etiologies such as trauma, obstruction, or inflammation. This article explores the diversity of treatment modalities proposed for ranula, including incision and drainage, marsupialization, and sublingual gland removal. The recurrence of ranula is discussed in relation to treatment types, with reported rates varying significantly. This article discusses a case study of intraoral swelling in a 19-year-old male patient, emphasizing the importance of understanding and managing ranula in clinical practice.

Tranexamic acid loaded in a physically crosslinked trilaminate dressing for local hemorrhage control: Preparation, characterization, and in-vivo assessment using two different animal models

This work aimed at formulating a trilaminate dressing loaded with tranexamic acid. It consisted of a layer of 3 % sodium hyaluronate to initiate hemostasis. It was followed by a mixed porous layer of 5 % polyvinyl alcohol and 2 % kappa–carrageenan. This layer acted as a drug reservoir that controlled its release. The third layer was 5 % ethyl cellulose backing layer for unidirectional release of tranexamic acid towards the wound. The 3 layers were physically crosslinked by hydrogen bonding as confirmed by Infrared spectroscopy. Swelling and release studies were performed, and results proposed that increasing number of layers decreased swelling properties and sustained release of tranexamic acid for 8 h. In vitro blood coagulation study was performed using human blood and showed that the dressing significantly decreased coagulation time by 70.5 % compared to the negative control. In vivo hemostatic activity was evaluated using tail amputation model in Wistar rats. Statistical analysis showed the dressing could stop bleeding in a punctured artery of the rat tail faster than the negative control by 59 %. Cranial bone defect model in New Zealand rabbits was performed to check for bone hemostasis and showed significant decrease in the hemostatic time by 80 % compared to the control.

Chitosan-based buccal mucoadhesive bilayer tablets enhance the bioavailability of tizanidine hydrochloride by bypassing the first-pass metabolism

Tizanidine hydrochloride (TZN) is an antimuscarinic agent used in the treatment of pain-related spasms, multiple sclerosis, and stroke-related spasticity. It has low oral bioavailability (40 %) due to excessive first-pass metabolism in the liver. The aim of this project was to enhance the systemic bioavailability of TZN by developing buccal mucoadhesive bilayer tablet formulations using chitosan salts with molecular weights of 136 kDa (7 cP) and 169 kDa (10 cP). Structural characterisation of chitosans and their salts was performed by FTIR, 1H NMR, DSC, TGA, and XRD analyses. Soluble chitosan salts, chitosan glutamate and chitosan chloride, for the adhesive layer, and insoluble ethyl cellulose for the impermeable backing layer were selected as polymers to fabricate the buccal tablets by direct compression method. The tablets containing TZN demonstrated high swelling and good mucoadhesion characteristics as well as released all the drug within 8 h. While TC10, formulated with 10 cP chitosan chloride, showed the highest swelling properties, TG10, prepared with 10 cP chitosan glutamate, exhibited the highest mucoadhesion. Chitosan glutamate tablets (TG7 and TG10) demonstrated better mucoadhesive characteristics and stability than chitosan chloride ones (TC7 and TC10) in the buccal medium based on the results of swelling and drug release studies. The permeability studies performed by Franz diffusion cell demonstrated that the amount of TZN passing through the bovine buccal mucosa was between 13.4 and 14.4 %. Stability studies conducted at 5 ± 2 °C, 25 ± 2 °C and 40 ± 2 °C for 6 months showed that no changes in the content uniformity and pH were observed. The in vivo comparative bioavailability studies in female New Zealand rabbits were performed and TZN-containing buccal mucoadhesive bilayer tablets fabricated with both chloride (TC10) and glutamate (TG10) salts of chitosan demonstrated three times higher bioavailability than the commercial TZN product (Sirdalud® oral tablet) administered by the gastrointestinal route.