Chitosan Powder Research Articles

High-salt-resistance aerogels composed of chitosan and anode powder for effective solar interfacial evaporation

Solar interfacial evaporation technology is widely utilized for seawater desalination and wastewater treatment, which are currently areas of significant research interest. The primary factors to consider when transitioning the evaporator from laboratory settings to practical applications are its mechanical stability and resistance to salt. In the present study, composite aerogels consisting of an anode powder (AP), polypyrrole (Ppy), and chitosan (CS) were produced by a conventional technique involving physical cross-linking and in situ growth. The resulting aerogel has a compact pore structure that enhances the scattering of light on its surface and increases the area available for evaporation. As a result, the material exhibits exceptional photothermal capabilities, with water evaporation rates and photothermal conversion efficiencies of 1.865 kg m−2 h−1 and 85.96%, respectively, when exposed to 1 sun illumination. Simultaneously, the aerogel exhibits exceptional efficacy in water purification and resistance to salt when employed for the treatment of heavy-metal wastewater, seawater, and highly concentrated saline solutions. Furthermore, the utilization of AP as a light-absorbing substance aligns with the principles of green chemistry by promoting the recycling and repurposing of waste materials. These results provide novel insights into the potential applications of lithium battery waste and the optimization of solar-interfacial-evaporator design.

Efficacy of chitosan powder in reducing vaginal bleeding following a loop electrosurgical excision procedure: A randomized control trial.

To evaluate the efficacy of topical chitosan powder in reducing postoperative vaginal bleeding following a loop electrosurgical excision procedure (LEEP). In this randomized controlled trial, patients who underwent LEEP were randomly assigned (1:1) to the chitosan group, in which the wound area was sprayed with chitosan powder using a spray pump, or the control group. The primary outcome was the median quantity of vaginal blood lost in the early postoperative period (defined as within 6 h of the procedure). The 124 women enrolled in the study were randomly divided into control (n = 61) and chitosan (n = 63) groups. The median amount of vaginal blood loss during the early postoperative period was significantly lower in the chitosan group than in the control group (198.85 [64.4-388.57] mL vs. 250.60 [67.7-552.87] mL; P < 0.001). The rate of late postoperative bleeding requiring hemostatic intervention was also lower in the chitosan group than in the control group (3.2% vs. 16.4%; P = 0.013). Superior cervical wound healing in the chitosan group compared to the control group was also observed. The application of chitosan powder to the cervical wound bed can improve surgical outcomes by decreasing post-LEEP vaginal bleeding and facilitating the healing of cervical wounds.

The Effectiveness of Concentration of Chitosan Extracted from Tiger Shrimp Shells as a Natural Preservative of Kenyar Fish

A study to find the effectiveness of chitosan concentration as a natural preservative on Kenyan fish (Sarda orientalis) has been conducted. The chitosan powder used is extracted from tiger prawn (Penaeus monodon) shells, and it is used in the form of a solution with a concentration of 1%, 1.5%, 2%, and 2.5%. Fresh kenyar fish of 500 g were soaked in those chitosan solutions and named A1, A2, A3, and A4, respectively. Two sample groups were prepared as a comparison; they weren’t treated with any chitosan solution; they were A02, 500 g of kenyar fish soaked in 2% acetic acid, and A01, 500 g of kenyar fish without any treatment. The soaking times were varied as 20, 40, and 60 minutes. Storage is carried out at room temperature. The activity of chitosan as a fish preservative was analyzed using various methods, including pH, organoleptic, and antimicrobial tests. The measurements of pH and organoleptic test were made at 0, 24, 48, and 72 hours. The antimicrobial tests were carried out after 24 hours of storage. The study concluded that the effective concentration of chitosan as a preservative agent of fresh kenyar fish is 2.5% (A4) with 40 minutes of soaking time, with the quality parameters are pH 5, an organoleptic score of 9, and the total number of microbes is 1.2 x 105 CFU/g.

Chitosan-Polyaniline (Bio)Polymer Hybrids by Two Pathways: A Tale of Two Biocomposites.

Previous research highlights the potential of polyaniline-based biocomposites as unique adsorbents for humidity sensors. This study examines several preparative routes for creating polyaniline (PANI) and chitosan (CHT) composites: Type 1-in situ polymerization of aniline with CHT; Type 2-molecular association in acidic aqueous media; and a control, Type 3-physical mixing of PANI and CHT powders (without solvent). The study aims to differentiate the bonding nature (covalent vs. noncovalent) within these composites, which posits that noncovalent composites should exhibit similar physicochemical properties regardless of the preparative route. The results indicate that Type 1 composites display features consistent with covalent and hydrogen bonding, which result in reduced water swelling versus Type 2 and 3 composites. These findings align with spectral and thermogravimetric data, suggesting more compact structure for Type 1 materials. Dye adsorption studies corroborate the unique properties for Type 1 composites, and 1H NMR results confirm the role of covalent bonding for the in situ polymerized samples. The structural stability adopts the following trend: Type 1 (covalent and noncovalent) > Type 2 (possible trace covalent and mainly noncovalent) > Type 3 (noncovalent). Types 2 and 3 are anticipated to differ based on solvent-driven complex formation. This study provides greater understanding of structure-function relationships in PANI-biopolymer composites and highlights the role of CHT as a template that involves variable (non)covalent contributions with PANI, according to the mode of preparation. The formation of composites with tailored bonding modalities will contribute to the design of improved adsorbent materials for environmental remediation to versatile humidity sensor systems.

Effect of carboxymethylated chitosan and cellulose acetate on mechanical properties of PLA blends for biomedical applications

Chitin and chitosan are versatile and valuable biomaterials, with chitosan being abundantly found in the exoskeletons of crustaceans, insects, arthropods, and mollusks. The chemical extraction of chitin involves a series of steps, including deproteinization, demineralization, and decolorization. Chitosan is often combined with various polymeric materials, and polymer blending can enhance the mechanical properties of the resulting bioproduct. In this study, composites of poly(lactic acid) (PLA) with chitosan (Ch) and cellulose acetate (CA) were successfully fabricated using extrusion and injection molding techniques. The chitosan content, ranging from 0 to 7.5 wt. %, was incorporated into the PLA matrix to assess the impact of filler content on the mechanical and morphological properties of the composites. The chitosan powder was first alkalized and then etherified to obtain modified chitosan, specifically o-carboxymethylated chitosan (O-CMCh). The addition of chitosan led to a reduction in tensile strength, flexural strength, modulus of elasticity, and impact strength. However, the hardness of the composite improved with the inclusion of chitosan. The mesoporous structure of chitosan was characterized using nitrogen adsorption and desorption measurements. Morphological analysis revealed that the composite containing 3.75 wt. % chitosan exhibited significantly less fracture surface compared to other composites.

Comparison of the Antimicrobial Efficacy of Conventional Versus Chitosan Re-inforced Heat-Polymerized Polymethylmethacrylate Dental Material: An In Vitro Study.

Polymethylmethacrylate (PMMA) is widely used in the fabrication of dentures due to its aesthetic appeal and mechanical strength. However, PMMA's susceptibility to microbial colonization often leads to oral infections such as denture stomatitis. Enhancing the antimicrobial properties of denture materials is crucial for improving patient outcomes.Chitosan, a natural biopolymer, possesses inherent antimicrobial properties and could potentially enhance the microbial resistance of PMMA. This study has investigated thepotential of chitosan-reinforced heat-polymerized PMMA denture material to reduce microbial colonization. The aim of the study was to evaluate and assess the anti-bacterial and antifungal properties of chitosan-reinforced heat-polymerized PMMA with conventional heat-polymerized PMMA Materials and methods:Chitosan-reinforced PMMA samples were fabricated with varying chitosan concentrations (0% control, 5%, 10%, and 15% by weight). The fabrication involved mixing chitosan powder with PMMA powder, adding monomer liquid, followed by mixing, packing, and curing using the conventional heat polymerization technique. The antimicrobial efficacy was assessed in vitro using two common oral pathogens: Streptococcus mutans and Candida albicans. Blood agar plates were used for S. mutans and Sabouraud agar plates were used for C. albicans. Each sample was placed on the respective agar plates inoculated with a standardized microbial suspension and incubated at 37°C for 24 hours. The number of colony-forming units (CFUs) was counted to quantify microbial growth. Statistical analyses, including linear regression analysis, one-way ANOVA test, and Pearson correlation were performed to evaluate the relationship between chitosan concentration and antimicrobial efficacy. The p-value was calculated to determine the statistical significance of the results. The chitosan-reinforced PMMA samples showed significantly greater antimicrobial efficacy compared to the conventional PMMA samples. The CFU counts for both S. mutans and C. albicans decreased with increasing chitosan concentration. Linear regression analysis indicated a strong negative correlation between chitosan concentration and CFU counts, with Pearson correlation coefficients of -0.97 for S. mutans and -0.98 for C. albicans. ANOVA analysis revealed a statistically significant difference in antimicrobial efficacy across different chitosan concentrations (p < 0.001). Incorporating chitosan into heat-polymerized PMMA significantly enhances its antimicrobial properties against S. mutans and C. albicans. The antimicrobial efficacy improves with higher concentrations of chitosan, with the 15% chitosan-reinforced samples showing the most substantial reduction in microbial growth. These results suggest that chitosan-reinforced PMMA dentures could be a superior alternative to conventional PMMA dentures, potentially reducing denture-related infections and improving oral health outcomes for denture wearers.

Enhancement of alkaline pretreatment-anaerobically digested sludge dewaterability by chitosan and rice husk powder for land use of biogas slurry

Alkaline pretreatment can improve the methane yields and dewatering performance of anaerobically digested sludge, but it still needs to be coupled with other conditioning methods in the practical dewatering process. This study utilized four different flocculants and a skeleton builder for conditioning of alkaline pretreatment-anaerobically digested sludge. Chitosan was found to be the most effective in dewatering the sludge. Chitosan coupled with rice husk powder further improved the dewatering performance, which reduced normalized capillary suction time, specific resistance to filtration, and moisture content by 98.7%, 82.0%, and 12.1%. For land use of biogas slurry as a fertilizer, chitosan conditioning promoted the growth of corn seedlings, while the other three flocculants diminished the growth of corn seedlings. Chitosan coupled with rice husk powder further promoted the growth of corn seedlings by 103.5%, 65.0%, and 53.7% in fresh weight, dry weight, and root length, respectively. Overall, chitosan coupled with rice husk powder not only enhanced the dewaterability of alkaline pretreatment-anaerobically digested sludge but also realized the resource utilization of agricultural waste.

Effects of Gamma-Synthesized Chitosan on Morphological, Thermal, Mechanical, and Heavy-Metal Removal Properties in Natural Rubber Foam as Sustainable and Eco-Friendly Heavy Metal Sorbents

The properties of natural rubber foam (NRF) containing gamma-synthesized chitosan (CS) powder were investigated to address the growing demand for efficient methods to treat industrial wastewater contaminated with heavy metals. The CS powder was prepared by irradiating chitin (CT) powder with varying doses of gamma rays (0–100 kGy), followed by deacetylation using 40% sodium hydroxide (NaOH) at 100 °C for 1 h. The resulting CS powders were then mixed with natural rubber latex (NRL) at different contents (0, 3, 6, and 9 parts per hundred parts of rubber by weight; phr) and processed using Dunlop techniques to prepare the foam samples. The experimental findings indicated that the degree of deacetylation (%DD) of the CS powder increased initially with gamma doses up to 60 kGy but then decreased at 80 and 100 kGy. In addition, when the CS powder was incorporated into the NRF samples, there were increases in total surface area, density, compression set, and hardness (shore OO), with increasing gamma doses and CS contents. Furthermore, the determination of heavy metal adsorption properties for Cu, Pb, Zn, and Cd showed that the developed NRF sample exhibited high adsorption capacities. For instance, their removal efficiencies reached 94.9%, 82.5%, 91.4%, and 97.0%, respectively, in NRF containing 9 phr of 60 kGy CS. Notably, all adsorption measurements were determined using 3 cm × 3 cm × 2.5 cm specimens submerged in respective metal solutions, with an initial concentration of 25 mg/L. However, the removal capacity per unit mass of the sample (mg/g) showed less dependencies on CS contents, probably due to the higher density of CS/NRF composites in comparison to pristine NRF, resulting in a smaller volume of the former being submerged in the solution, subsequently suppressing the effects from CS in the adsorption. Lastly, tests on the reusability of the developed NRF indicated that the samples could be reused for up to three cycles, with the Cu removal capacity remaining relatively high (83%) in the sample containing 9 phr of 60 kGy CS. The overall outcomes implied that the developed NRF with the addition of gamma-synthesized CS not only offered effective and eco-friendly heavy metal adsorption capacity to improve public health safety and the environment from industrial wastewater but also promoted greener and safer procedures for the synthesis/modification of similar substances through radiation technologies.

Enhancing antioxidant properties of lime juice powder through polyelectrolyte microparticles of chitosan-alginate: Formulation, characterization and stability study.

Lime (Citrus aurantifolia) juice was reported to contain ascorbic acid (AA) and flavonoids, which has bioactivity as antioxidants. To develop an antioxidant product, improving its stability is necessary due to the perishable characteristics of compounds in lime. Therefore, the formulation of polyelectrolyte microparticles using chitosan and alginate was conducted to overcome the weaknesses. This study aims to evaluate the effect of various chitosan, alginate, and lime juice powder (LJP) concentrations on the physical characteristics and antioxidant activity of LJP encapsulated in chitosan-alginate microparticles (CALM). Microparticles with various concentrations of chitosan and alginate were prepared by ionic gelation method using CaCl2 as a crosslinker. The microparticles were evaluated for its physical properties and its antioxidant activity using 2-2-diphenyl-1-picrylhydrazyl reagent. A one-way ANOVA test and Tukey's honest significant difference post hoc were used to determine the effect of LJP amount on the antioxidant activity. The highest AA content in CALM was 0.14 mg/100 mg, with a % encapsulation efficiency of 18.38% ± 0.02%. Antioxidant activity tests revealed that LJP possessed the strong antioxidant activity with an IC50 value of 32.59 μg/mL, whereas IC50 values of the microparticles ranged from 24.79 ± 0.03 μg/mL to 39.96 ± 0.07 μg/mL. During storage, the IC50 of LJP decreased from 32.59 ± 0.13 μg/mL to 65.53 ± 0.03 μg/mL, whereas the IC50 of microparticles remained stable. This study concluded that the chitosan-alginate polyelectrolyte microparticle formulation can improve and protect LJP's antioxidant activity.

Superporous sponge prepared by secondary network compaction with enhanced permeability and mechanical properties for non-compressible hemostasis in pigs

Developing superporous hemostatic sponges with simultaneously enhanced permeability and mechanical properties remains challenging but highly desirable to achieve rapid hemostasis for non-compressible hemorrhage. Typical approaches to improve the permeability of hemostatic sponges by increasing porosity sacrifice mechanical properties and yield limited pore interconnectivity, thereby undermining the hemostatic efficacy and subsequent tissue regeneration. Herein, we propose a temperature-assisted secondary network compaction strategy following the phase separation-induced primary compaction to fabricate the superporous chitosan sponge with highly-interconnected porous structure, enhanced blood absorption rate and capacity, and fatigue resistance. The superporous chitosan sponge exhibits rapid shape recovery after absorbing blood and maintains sufficient pressure on wounds to build a robust physical barrier to greatly improve hemostatic efficiency. Furthermore, the superporous chitosan sponge outperforms commercial gauze, gelatin sponges, and chitosan powder by enhancing hemostatic efficiency, cell infiltration, vascular regeneration, and in-situ tissue regeneration in non-compressible organ injury models, respectively. We believe the proposed secondary network compaction strategy provides a simple yet effective method to fabricate superporous hemostatic sponges for diverse clinical applications.

Enhancing Wastewater Depollution: Sustainable Biosorption Using Chemically Modified Chitosan Derivatives for Efficient Removal of Heavy Metals and Dyes.

Driven by concerns over polluted industrial wastewater, particularly heavy metals and dyes, this study explores biosorption using chemically cross-link chitosan derivatives as a sustainable and cost-effective depollution method. Chitosan cross-linking employs either water-soluble polymers and agents like glutaraldehyde or copolymerization of hydrophilic monomers with a cross-linker. Chemical cross-linking of polymers has emerged as a promising approach to enhance the wet-strength properties of materials. The chitosan thus extracted, as powder or gel, was used to adsorb heavy metals (lead (Pb2+) and copper (Cu2+)) and dyes (methylene blue (MB) and crystal violet (CV)). Extensive analysis of the physicochemical properties of both the powder and hydrogel adsorbents was conducted using a range of analytical techniques, including Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), Brunauer-Emmett-Teller (BET), and scanning electron microscopy (SEM), as well as 1H and 13C nuclear magnetic resonance (NMR). To gain a comprehensive understanding of the sorption process, the effect of contact time, pH, concentration, and temperature was investigated. The adsorption capacity of chitosan powder for Cu(II), Pb(II), methylene blue (MB), and crystal violet (CV) was subsequently determined as follows: 99, 75, 98, and 80%, respectively. In addition, the adsorption capacity of chitosan hydrogel for Cu(II), Pb(II), MB, and CV was as follows: 85, 95, 85, and 98%, respectively. The experimental data obtained were analyzed using the Langmuir, Freundlich, and Dubinin-Radushkevich isotherm models. The isotherm study revealed that the adsorption equilibrium is well fitted to the Freundlich isotherm (R2 = 0.998), and the sorption capacity of both chitosan powder and hydrogel was found to be exceptionally high (approximately 98%) with the adsorbent favoring multilayer adsorption. Besides, Dubinin has given an indication that the sorption process was dominated by Van der Waals physical forces at all studied temperatures.

The use of chitosan aerogels as an adsorbent for the regeneration of frying oil

One of the most commonly used food preparation methods is deep-fat frying. The improvement of the quality of used frying oil (UFO) is important because the reuse of frying oil could provide significant savings to the food industry. This study aimed to enhance the quality of used sunflower oil by using chitosan aerogels (CA), which can be considered as novel adsorbents with an increased surface area compared to chitosan powder. Aerogels are novel nanostructured materials with high porosity and large surface area. In this study, CA were produced by drying the 2% (w/v) chitosan gels using supercritical drying. In the study, 32 consecutive deep-fat frying were performed using potato slices in sunflower oil at 180 ± 5 °C. The effect of the adsorbent concentration (0.5, 1, and 2% (w/w)) and different adsorption temperatures (90, 135, and 180 °C) were studied by examining the UFO before and after the adsorption treatments. The physicochemical properties of the oil were analyzed by determining free fatty acid (FFA) content, total polar compounds (TPC), smoke point, p-anisidine value (p-AnV), and color (CIE L*, a*, b*). Moreover, the structural changes of aerogels after the adsorption process were investigated by Fourier Transform Infrared spectroscopy (FTIR) and Nuclear Magnetic Resonance (NMR). CA could reduce the % FFA values from 0.44% to 0.18% due to the ionic interaction between CA and FFA. In addition, TPC value and the smoke point increased after the treatments. The p-AnV was compensated with CA, indicating that secondary oxidation products were adsorbed. Moreover, CA caused a darker color after the adsorption treatments. Additionally, compared with magnesium silicate, the same concentrations of CA were found more effective in improving all the quality parameters of oil except for the L* values.

Clotting Blood into an Adhesive Gel by Hemostatic Powder Based on Cationic/Anionic Polysaccharides and Laponite.

Hemostatic powder is widely employed for emergency bleeding control due to its ability to conform to irregularly shaped wounds, ease of use, and stable storage. However, current powders exhibit limited tissue adhesion and insufficient support for thrombus formation, making them easily washed away by blood. In this study, a hybrid powder (QAL) was produced by mixing quaternized chitosan (QCS) powder, catechol-modified alginate (Cat-SA) powder, and laponite (Lap) powder. Upon addition of QAL, the blood quickly transformed to a robust and adhesive blood gel. The adhesion strength of the blood gel was up to 31.33 ± 1.56 kPa. When compared with Celox, QAL showed superior performance in promoting hemostasis. Additionally, QAL exhibited effectiveness in eliminating bacteria while also demonstrating outstanding biocompatibility with cells and blood. These favorable properties, including strong coagulation, adhesion to wet tissue, antibacterial activity, biosafety, ease of use, and stable storage, make QAL a promising emergency hemostatic agent.

Adsorption, Kinetic and Thermodynamic Studies for the Adsorption of Cadmium onto Combination of Chitosan and Coffee Ground Activated Carbon

The presence of cadmium in water due to its natural mobility can cause the nature of the water to become toxic and threaten the surrounding ecosystem when it accumulates in the food chain. The aim of this study was to investigate the maximum adsorption capacity using an isothermal model, to determine the rate of adsorption kinetics using chitosan and coffee powder adsorbents in reducing cadmium concentrations in industrial wastewater, and to investigate its thermodynamic magnitude. The research method was applied with laboratory experiments followed by quantitative data analysis to determine the isothermal model and adsorption kinetics. The results showed that the adsorption isotherm follows the Langmuir isotherm model with a correlation coefficient of 0.9970 and a maximum adsorption capacity of 0.7546 mg.g-1, which indicates that the chemical adsorption occurs in a monolayer, where the adsorption sites are homogeneously distributed with the adsorption energy. Permanent and negligible interactions between cadmium molecules (adsorbate) and adsorbent. Thus the pseudo second order kinetic model is a better way to explain the reaction rate for cadmium in combination chitosan and coffee ground activated carbon. Negative ΔGo values indicate that the adsorption reaction takes place spontaneously, ΔHo of 0.3467 indicates an endothermic reaction, and ΔSo of 3.5296 indicates an increase in the randomness of the adsorption process at the adsorbent interface and cadmium during adsorption.

The Effect of Chitosan Incorporation on Physico-Mechanical and Biological Characteristics of a Calcium Silicate Filling Material.

A tricalcium silicate-based cement, Biodentine™, has displayed antibiofilm activity when mixed with chitosan powder. This study aimed to assess the effect of chitosan incorporation on the physico-mechanical and biological properties of Biodentine™. In this study, medium molecular weight chitosan powder was incorporated into Biodentine™ in varying proportions (2.5 wt%, 5 wt%, 10 wt%, and 20 wt%). The setting time was determined using a Vicat apparatus, solubility was assessed by calculating weight variation after water immersion, radiopacity was evaluated and expressed in millimeters of aluminum, the compressive strength was evaluated using an Instron testing machine, and the microhardness was measured with a Vickers microhardness tester. In addition, surface topography of specimens was analyzed using scanning electron microscopy, and the effect of chitosan on the viability of human embryonic kidney (HEK 293) cells was measured by a colorimetric MTT assay. Incorporation of 2.5 wt% and 5 wt% chitosan powder delivered an advantage by speeding up the setting time of Biodentine material. However, the incorporation of chitosan compromised all other material properties and the crystalline structure in a dose-dependent manner. The chitosan-modified material also showed significant decreases in the proliferation of the HEK 293 cells, signifying decreased biocompatibility. Chitosan incorporation into calcium silicate materials adversely affects the physical and biological properties of the material. Despite the increased antimicrobial activity of the modified material, the diminution in these properties is likely to reduce its clinical value.

Hydrophobic and antibacterial properties of textiles using nanocomposite chitosan and SiO2 from rice husk ash as-coating

This research aims to develop hydrophobic and antibacterial properties of textiles using chitosan and silica oxide (SiO2) nanocomposite coating. SiO2 was extracted from rice husk ash and chitosan from crustacean shells. SiO2 and chitosan powder were pulverized using High Energy Milling (HEM). The nanocomposite was synthesized using the sol-gel method with concentration variations of 0.2 %:0.4 %, 0.4 %:0.6 %, 0.6 %:0.8 %, and 0.8 %:1 %. Textile coating was carried out by dip coating method with variations of 1x, 2x, 3x, and 4x dyeing. The crystal structure and size of the nanocomposites were obtained using X-ray Diffraction (XRD). Surface morphology and particle size were obtained using a Scanning Electron Microscope (SEM). The contact angle was measured using the sessile drop method. The bacterial activity tests were conducted by measuring the surface temperature of textiles with a thermal camera after being irradiated with UV-C. The ability of textiles to inhibit bacterial growth was tested using Staphylococcus aureus bacteria. The results showed that the smallest crystal size obtained was 30.21 nm. The amount of particle size and contact angle are significantly influenced by the quality of Citosan-SiO2 and coloring changes. The smallest particle size obtained is 32 nm. The highest value of contact angle obtained was 161° The average surface temperature of the textile after being irradiated with UV-C reached 40.7 °C. The highest zone of inhibition obtained was 17 mm and is in the strong category. This research shows that textiles coated with chitosan-SiO2 can inhibit bacterial growth and have potential applications in the clothing industry.

Chitosan as an Alternative to Oil-Based Materials for the Fabrication of Lab-on-a-Chip.

Given the growing importance of lab-on-a-chip in a number of fields, such as medical diagnosis or environmental analysis, the fact that the current fabrication process relies mainly on oil-based polymers raises an ecological concern. As an eco-responsible alternative, we presented, in this article, a manufacturing process for microfluidic devices from chitosan, a bio-sourced, biodegradable, and biocompatible polysaccharide. From chitosan powder, we produced thick and rigid films. To prevent their dissolution and reduce their swelling when in contact with aqueous solutions, we investigated a film neutralization step and characterized the mechanical and physical properties of the resulting films. On these neutralized chitosan films, we compared two micropatterning methods, i.e., hot embossing and mechanical micro-drilling, based on the resolution of microchannels from 100 µm to 1000 µm wide. Then, chitosan films with micro-drilled channels were bonded using a biocompatible dry photoresist on a glass slide or another neutralized chitosan film. Thanks to this protocol, the first functional chitosan microfluidic devices were prepared. While some steps of the fabrication process remain to be improved, these preliminary results pave the way toward a sustainable fabrication of lab-on-a-chip.

FcLR-Chitosan/Pullulan nanofibers: Boosted antibacterial activity and decreased cytotoxicity

Natural and environmentally benign electrospun polymeric nanofibers (NFs) with distinctive features, unique physiochemical and biological properties, and high susceptibility to carry non-toxic antibacterial cargoes, e.g., ferrocenyl-based compounds, have emerged as a neo-tool for killing bacteria. Here, the antibacterial FcLR-Chit/Pull NFs were fabricated through three steps: 1) synthesis of FcLR-Chit via the attachment of chitosan to Ferrocenyl Lawesson’s Reagent (FcLR), 2) blending of the FcLR-Chit at various concentrations with the natural polymer of pullulan, and 3) electrospinning. The successfully characterized FcLR-Chit/Pull NFs with a homogenous distribution of FcLR-Chit inside the pullulan matrix were thermally stable up to 270–290 ºC and mechanically stable with an increased elongation at break (EAB) (30.0–42.2%) and decreased tensile strength (TS) (1.1–2.3 MPa) compared to the pure pullulan NFs with the EAB of 19.0% and TS of 3.6 MPa. Pure pullulan NFs and FcLR-Chit/Pull NFs (0.1 wt%, 1.0 wt%, and 5.0 wt%) showed insignificant cytotoxicity on the fibroblast cell lines (L929). The antibacterial activity was detected in the trend of FcLR-Chit/Pull NFs (5.0 wt%)>FcLR-Chit powder (5.0 wt% in water)>FcLR-Chit/Pull NFs (1.0 wt%)>FcLR powder (5.0 wt% in water)>FcLR-Chit/Pull NFs (0.1 wt%)>chitosan powder (5.0 wt% in water)> pure pullulan NFs. The FcLR-Chit/Pull NFs (5.0 wt%) with an average diameter of 365 nm, insignificant cytotoxicity on L929 cells within 24 h and 48 h, and boosted antibacterial activity with the inhibition zone diameter of 1.95 mm against Gram-negative E. Coli and 1.76 mm against Gram-positive S. aureus bacteria were chosen as the optimal nanofibrous candidate for the future bactericidal applications.

Effects of chitosan and rice husk powder on thermal hydrolysis-anaerobic digested sludge conditioning: Dewaterability and biogas slurry fertility

To enhance the dewaterability of anaerobic digested sludge and to make full use of the biogas slurry. This study set up five sludge conditioning methods: polymeric ferric sulfate, polymeric aluminum chloride, cationic polyacrylamide, chitosan, and chitosan combined with rice husk powder. Their effects on the dewaterability of thermal hydrolysis-anaerobic digested sludge, bacterial community, and biogas slurry fertility were studied to find a non-toxic and non-risk dewatering technology for the environment and biogas slurry. Compared with that of the control group, moisture content, normalization capillary suction time, and specific resistance to filtration were reduced by 12.8%, 97.7%, and 82.9%, respectively. Chitosan enlarges the sludge flocs and forms complexes with proteins, disrupting the structure of the extracellular polymeric substances, thereby exposing more hydrophobic groups and reducing the hydrophilicity of the sludge. The subsequent addition of rice husk powder enhances the adsorption of hydrophilic substances and provides a stronger drainage channel for the sludge. In addition, the biogas slurry obtained by this conditioning method used as a fertilizer increased the dry weight and fresh weight of corn seedlings by 59.3% and 91.0%, respectively. And the total chlorophyll content increased by 84.6%. Pearson's correlation analysis showed that chitosan and rice husk meal had no toxic effect on the biogas slurry compared to the other three flocculants. The results showed that the combined treatment of chitosan and rice husk powder resulted in the best dewaterability. Overall, chitosan combined with rice husk powder is a green dewatering technology with great potential for anaerobic digested sludge dewatering and biogas slurry recycling.

Effectiveness of Chitosan versus Natural Aloe Vera on Candida Adherence in Denture Soft Lining Material.

Soft denture lining materials act as a cushion between the denture base and tissues. Alongside having many advantages, its main problem is candida growth due to its rubbery and porous texture. Many interventions have been performed to halt the growth of candida within soft lining materials such as the use of antifungal therapy and strict oral and denture hygiene but there are consequences such as recurrence, drug resistance, and toxicity related to these interventions. Since natural agents such as aloe vera and chitosan have been proven to have antibacterial and antifungal properties with minimum adverse effects, this study aimed to study the effectiveness of chitosan and aloe vera powders incorporated within denture soft lining materials against candida adherence. Methodology. A total of 60 soft-lining material samples were prepared that were equally divided into three groups, viz., group 1 (chitosan incorporation), group 2 (aloe vera incorporation), and group 3 (control). Candida was obtained from the microbiology lab to form a candidal suspension, diluted in 0.9% NaCl to match the McFarland standard bacteriologic solution. Samples were incubated at 37°C for 24 hours in test tubes containing 100 mL of the candidal suspension and 9.9 mL of the previously prepared Sabouraud dextrose agar. Crystal violet stain was used to stain the adhering cells by fixing them with methanol 80%. For each sample, the adhering candida cells were counted on three standard fields by using an inverted light microscope, and the mean of those fields was recorded. The mean value for samples containing aloe vera was 41.15, while the mean values for samples containing chitosan and the control group were 16.05 and 79.1, respectively. Of all the three groups, aloe vera powder had a significant efficacy against candida growth as compared to the chitosan and control groups (P value = 0.001). Both herbal agents were effective against candida growth. In comparison, aloe vera was more effective against candida growth compared to chitosan.