Weight Ratio Of Chitosan Research Articles

Assessment of chitosan-PVA hydrogels infused with marine collagen peptides for potential wound healing applications

Ideal wound dressings should show enhanced moisture management at the wound site, antibacterial and physical barrier, and mechanical robustness. Additionally, it should be easy to apply to the wound and be biocompatible and non-toxic. In this study, a linker-free freeze-thaw procedure was used to create an array of chitosan/PVA hydrogels blended with commercially available marine collagen peptides. Marine collagen peptides (CP) are easily available as by-products of the marine food industry and are an inexpensive and novel source of biomaterial in this field. The different weight ratios of chitosan, PVA, and CP influenced the hydrogel properties such as swelling, gel content, evaporation, and mechanical properties. Furthermore, SEM and ATR-FTIR were used to characterize the hydrogels generated under ideal conditions. After 24 h, the optimum hydrogel (chitosan:PVA:CP ratio of 1:5:1) showed a water absorption capacity of up to 900 %, a gel content of 80 %, and a 40 % evaporation rate. The physical interactions between marine collagen peptide and gel-forming components were validated by ATR-FTIR spectra, and the hydrogel kept a sufficient porous structure for potential wound dressing application. To test the mechanical integrity of the hydrogels, compression testing was carried out showing a compressive modulus of up to ∼40 kPa. The addition of marine collagen peptide in the chitosan/PVA hydrogel increased its wettability, antimicrobial capabilities, and hemostatic properties. Furthermore, the hydrogel preparation procedure is simple and does not use toxic chemicals, serving as a model for developing safe and effective hydrogel wound dressing.

Alternating Current Electrospinning of Polycaprolactone/Chitosan Nanofibers for Wound Healing Applications.

Traditional wound dressings have not been able to satisfy the needs of the regenerative medicine biomedical area. With the aim of improving tissue regeneration, nanofiber-based wound dressings fabricated by electrospinning (ES) processes have emerged as a powerful approach. Nowadays, nanofiber-based bioactive dressings are mainly developed with a combination of natural and synthetic polymers, such as polycaprolactone (PCL) and chitosan (CHI). Accordingly, herein, PCL/CHI nanofibers have been developed with varying PCL:CHI weight ratios (9:1, 8:2 and 7:3) or CHI viscosities (20, 100 and 600 mPa·s) using a novel alternating current ES (ACES) process. Such nanofibers were thoroughly characterized by determining physicochemical and nanomechanical properties, along with wettability, absorption capacity and hydrolytic plus enzymatic stability. Furthermore, PCL/CHI nanofiber biological safety was validated in terms of cytocompatibility and hemocompatibility (hemolysis < 2%), in addition to a notable antibacterial performance (bacterial reductions of 99.90% for S. aureus and 99.91% for P. aeruginosa). Lastly, the enhanced wound healing activity of PCL/CHI nanofibers was confirmed thanks to their ability to remarkably promote cell proliferation, which make them ideal candidates for long-term applications such as wound dressings.

Development of Active Antibacterial CEO/CS@PLA Nonwovens and the Application on Food Preservation.

The biodegradable activity antibacterial materials have been widely applied on food preservation because they not only protect foods from pathogenic attacks but also relieve environmental pollution. Biodegradable melt-blown nonwovens (MB) have several advantages over the other materials in terms of a simpler and more environmentally friendly fabrication process, higher specific surface area, and lower cost. Herein, polylactic acid (PLA) MB is first modified by polydopamine (PDA) to activate the surface. Then, chitosan (CS) and cinnamon essential oil (CEO) are used to decorate the surface of the modified PLA MB via a simple one-pot method to prepare CEO/CS@PLA MB with different CEO contents. Compared with PLA MB, CEO/CS@PLA MB had a rougher surface and larger average fiber diameter, while the average pore diameter and air permeability reduced. The input of CEO led to a decrease in the tensile strength of CEO/CS@PLA MB and an obvious increase in the elongation at break. The combination of CS and CEO shows excellent synergistic antibacterial effect. The antibacterial efficiencies of CEO/CS@PLA MB against Escherichia coli and Staphylococcus aureus enhance with the increase of the CEO content. When the weight ratio of CS to CEO is 1:2, the antibacterial efficiencies of CEO2/CS@PLA MB against E. coli and S. aureus are 99.98 and 99.99%, respectively. When being applied to the preservation of fresh strawberry, CEO2/CS@PLA MB can effectively inhibit the microbial growth in strawberry and reduce decay, which extends the shelf time of strawberry.

Adsorptive elimination of methylene blue dye from aqueous solution by chitosan‐nSiO2 nanocomposite: Adsorption and desorption study, scale‐up design, statistical, and genetic algorithm modeling

AbstractHeavy metals and organic dyes in water in concentrations exceeding the tolerable limit are unsafe for aquatic life and humans. Chitosan nanocomposites show a potential adsorption capacity to organic dyes. The present study encompasses the preparation of chitosan‐nSiO2 nanocomposites (CSNC) with different weight ratios of chitosan to nSiO2 and its application in the methylene blue (MB) dye adsorption. The nanocomposites were characterized with the help of SEM, BET, FTIR, XRD, and TGA. The adsorption experimentation was executed in batch mode under varying experimental conditions. Several isotherm and kinetic models were analyzed with the experimental data, and thermodynamic conditions required for adsorption were also determined. Maximum Langmuir adsorption capacities (qL) of the adsorbents for MB varied in the range of 21.32–31.34 mg g−1. The pseudo‐second‐order model was the best‐fitted kinetic model concerning all three adsorbents. The statistical modeling using multiple polynomial regression (MPR) for CWS CSNC1‐1 and CSNC2‐1 yielded the equations with R‐square ranging from 0.984 to 0.996. For GA modeling, it is more than 0.999. So, the efficient employment of statistical modeling, and genetic algorithms has also been achieved.

Montmorillonite/Tripolyphosphate Crosslinked Chitosan Nanocomposites for Eco-Friendly Agricultural Applications

Natural montmorillonite (MMT) was facilely impregnated with a mixed solution of protonated chitosan (CS) and KNO3, which was then subsequently impregnated with sodium tripolyphosphate (TPP) to ionically crosslink with chitosan, resulting in the MMT/xCS-20KNO3-TPP nanocomposites. The initial content of chitosan to MMT was varied from 2.5, 5 and 10 wt%, and while the TPP:chitosan weight ratio was kept at 1:5. The K+ and NO3- ions interacted ionically and were entrapped in the MMT basal spacing and the free volume of TPP crosslinked chitosan of the MMT/xCS-20KNO3-TPP nanocomposites. These nanocomposites were able to successfully prolong the K+ and NO3- releases, in which the cumulative released values (%R) ranging from 21 – 26 % for K+ and 0.37 – 0.65 % for NO3-. The presence of protonated amine in the chitosan played the dominant effect on the release profile of NO3- ion more than that of the K+ ion. The higher the chitosan content employed in the impregnation method, the more crosslinked chitosan structure in the MMT/xCS-20KNO3-TPP nanocomposites, resulting in decreased K+ and NO3- releases at each pre-determined soaking duration. The MMT/xCS-20KNO3-TPP nanocomposites have been considered as a promising choice for environmentally friendly fertilizers.

Application of biodegradable colorimetric films based on purple tomatoes anthocyanins loaded chitosan and polyvinyl alcohol in pork meat.

A series of biodegradable colorimetric films were prepared by using chitosan and polyvinyl alcohol as matrix, in which, the weight ratio of chitosan: Polyvinyl alcohol was 100: 0, 80: 20, 50: 50, 20: 80, or 0: 100, with addition of 10% (w/w, relative to chitosan) anthocyanins extracted from purple tomatoes (purple tomatoes anthocyanin) as pigment. The aim of this study was to observe the effect of weight ratio (chitosan: Polyvinyl alcohol) on the mechanical properties, contact angle, swelling rate, pH sensitivity, antioxidant properties of chitosan-polyvinyl alcohol/purple tomatoes anthocyanins films, and the antibacterial activity of films produced for pork packaging. In addition, the films as a smart colorimetric indicator for monitoring the freshness of pork was investigated. The results showed that as the ratio of chitosan to polyvinyl alcohol decreases, the elongation at break, hydrophilicity, and swelling rate of the films increased especially from 16.5% to 174.2% for elongation at break and 93.0° to 53.8° for water contact angle, however, the tensile strength decreased from 67.3 to 24.7 MPa. With decreasing of chitosan: Polyvinyl alcohol, the antibacterial activity on pork was decreased, and the antioxidant properties of films increased first then decreased. Fourier transform infrared spectroscopy indicated there were interactions among chitosan, polyvinyl alcohol, and purple tomatoes anthocyanins. The color response of films was depended on pH, as well as the immersion time. The longer immersion resulted in a more pronounced color change. The color changed from purplish red (pH 2-4) to green (pH 5-10) to yellow (pH 10-12). In monitoring the freshness of pork, the film showed a nice visual color change, indicating a potential application in smart packaging. These bio-based materials may be useful alternatives to synthetic plastics for food applications such as active and smart packaging, thereby improving the environmental friendliness and sustainability of the food supply.

Fabrication of Carum copticum essential oil-loaded chitosan nanoparticles and evaluation its insecticidal activity for controlling Rhyzopertha dominica and Tribolium confusum.

Plant essential oils (EOs) can be used as a feasible tool for insect pest control. Nanoparticle formulations of plant EOs can improve the efficiency and stability of EOs, as well as insecticidal potential. In this study, Carum copticum L. essential oil-loaded nanoparticles (OLNs) were prepared via an oil-in-water emulsion, followed by droplet solidiffication via ionic gelation using a cross-linker, sodium tripolyphosphate (TPP). The nanoparticles were characterized by ultraviolet and visible (UV-Vis) spectrophotometry, Fourier-transform infrared spectroscopy (FTIR), laser light scattering (LS), transmission electron microscopy (TEM), and scanning electron microscopy (SEM). Moreover, the insecticidal activity of C. copticum EO and OLNs was evaluated against Rhyzopertha dominica (F.) (Coleoptera: Bostrychidae) and Tribolium confusum Jacquelin du Val. (Coleoptera: Tenebrionidae). In addition, their effectiveness was assessed on the progeny production of tested insect species. The loading efficiency ranged from 34.33 to 84.16% when the chitosan to EO weight ratio was 1:1.25 and 1:0.5, respectively. The loading efficiency decreased with increasing EO content in the nanoparticles. The OLN particles exhibited spherical shape. The particle size was in the range 120-223.6 nm and increased with the increase of EO to chitosan ratio. So that the largest mean particle size (223.6 nm) was reported in the 1:1.25 weight ratio of chitosan to the EO. The mortality percentage of R. dominica and T. confusum adults were 74 and 57% when exposed for 7 days to 2000 mg/kg of OLNs at the 1:1.25 weight ratio, while EO caused 62 and 44% mortality on both insect species, respectively. Therefore, OLNs can potentially improve the insecticidal activity of C. copticum EO and could be applied to facilitate control of stored-product insect pests.

A pH-sensitive drug delivery using biodegradable succinoglycan/chitosan hydrogels with synergistic antibacterial activity

Since succinoglycan (SG) produced by Sinorhizobium meliloti is an anionic polysaccharide having substituents such as succinate and pyruvate groups, a polyelectrolyte composite hydrogel can be made together with chitosan (CS), a cationic polysaccharide. We fabricated polyelectrolyte SG/CS hydrogels using the semi-dissolving acidified sol-gel transfer (SD-A-SGT) method. The hydrogel showed optimized mechanical strength and thermal stability at an SG:CS weight ratio of 3:1. This optimized SG/CS hydrogel exhibited a high compressive stress of 497.67 kPa at 84.65 % strain and a high tensile strength of 9.14 kPa when stretched to 43.73 %. Additionally, this SG/CS hydrogel showed a pH-controlled drug release pattern for 5-fluorouracil (5-FU), where a change from pH 7.4 to 2.0 increased the release from 60 % to 94 %. In addition, this SG/CS hydrogel not only showed a cell viability of 97.57 %, but also showed synergistic antibacterial activity of 97.75 % and 96.76 % against S. aureus and E. coli, respectively. These results indicate the potential of this hydrogel as a biocompatible and biodegradable hydrogel material for wound healing, tissue engineering, and drug release systems.

Synthesis of chitosan‐nTiO2 nanocomposite, application in adsorptive removal of Cu(II)—Adsorption and desorption study, mechanism, scale‐up design, statistical, and genetic algorithm modeling

The present study comprises the preparation of chitosan‐nTiO2 nanocomposites and their characterization with the help of scanning electron microscopy (SEM), Brunauer–Emmett–Teller (BET), Fourier transform infrared spectroscopy (FTIR), X‐ray diffraction (XRD), and thermogravimetric analysis (TGA). Various adsorbent samples are prepared with different weight ratios of chitosan to nTiO2. The adsorption capacity of the prepared adsorbents towards Cu(II) in an aqueous solution is also tested. The adsorption experiment is performed in batch mode under varying experimental conditions. Several isotherm and kinetic models are analyzed with the experimental data, and thermodynamic conditions required for adsorption are also determined. The highest elimination of Cu(II) was 39.19% with the adsorbent chitosan without nTiO2 (CWT) with 20 mg L−1 initial Cu (II) concentration at adsorbent dosage 3 gL−1 and 98.5% with the adsorbent CTNC1‐1 (chitosan/nTiO2 nanocomposite with the mass proportions of chitosan:nTiO2 = 1:1) and 93% with CTNC2‐1 (chitosan/nTiO2 nanocomposite with the mass proportions of chitosan:nTiO2 = 2:1) with 10 mg L−1 initial Cu(II) concentration at adsorbent dosage 5 g L−1. The isotherm model confirmed the monolayer adsorption. Maximum Langmuir adsorption capacities (qL) of the adsorbents for Cu(II) were given as CTNC1‐1 &gt; CTNC2‐1 &gt; CWT. The pseudo‐second‐order model excellently depicted the kinetic process with good correlation for all adsorbents. The statistical (R‐square is more than 0.99) and genetic algorithm (GA) model (R‐square is more than 0.99) effectively predicted the percentage removal of Cu(II).

Highly absorbent antibacterial chitosan-based aerogels for shelf-life extension of fresh pork

In this study, the CS-DAS aerogels were prepared using chitosan (CS) crosslinked by dialdehyde starch (DAS), with the best absorption and mechanical properties at the weight ratio of CS to DAS being 7:3. The copper nanoparticles (CuNPs) were first prepared by green reduction method, then encapsulated by liposomes (Lip-CuNPs) for controlling their sudden release. The antibacterial aerogels (CD/Lip-CuNPs) were developed by incorporating the Lip-CuNPs into the aerogel (7:3). The porous network structure of aerogels realized the further gradual release of CuNPs. The CD/Lip-CuNPs aerogels had good antimicrobial properties, which could preserve fresh pork for 14 d at 4 °C without spoilage. Moreover, the CuNPs migrated from the aerogels into fresh pork was at a safe level of 3.38 mg/kg after 14 d at 4 °C. The obtained antibacterial CD/Lip-CuNPs aerogels had the potential for extending the shelf life of fresh meat. • Dialdehyde starch significantly improved the quality of chitosan-based aerogels. • The liposomes encapsulated copper nanoparticles (Lip-CuNPs) were prepared. • S uperabsorbent antibacterial aerogels were developed by incorporating Lip-CuNPs. • Selected aerogels realized the gradual release of copper nanoparticles. • Superabsorbent antibacterial aerogels extend the shelf life of fresh pork.

Surfactant-Free Chitosan/Cellulose Acetate Phthalate Nanoparticles: An Attempt to Solve the Needs of Captopril Administration in Paediatrics.

The Paediatric Committee of the European Medicines Agency encourages research into medicinal products for children, in particular, the development of an age-appropriate formulation of captopril is required in the cardiovascular therapeutic area. The aim of this study was the development of a liquid formulation using nanoparticles based only on chitosan and cellulose acetate phthalate containing captopril for the treatment of hypertension, heart failure and diabetic nephropathy in paediatric patients. Nanoparticles were prepared by a nanoprecipitation method/dropping technique without using surfactants, whose use can be associated with toxicity. A range of different cellulose to chitosan weight ratios were tested. A good encapsulation efficiency (61.0 ± 6.5%) was obtained when a high chitosan concentration was used (1:3 ratio); these nanoparticles (named NP-C) were spherical with a mean diameter of 427.1 ± 32.7 nm, 0.17 ± 0.09 PDI and +53.30 ± 0.95 mV zeta potential. NP-C dispersion remained stable for 28 days in terms of size and drug content and no captopril degradation was observed. NP-C dispersion released 70% of captopril after 2 h in pH 7.4 phosphate buffer and NP-C dispersion did not have a cytotoxicity effect on neonatal human fibroblasts except at the highest dose tested after 48 h. As a result, chitosan/cellulose nanoparticles could be considered a suitable platform for captopril delivery in paediatrics for preparing solid/liquid dosage forms.

Evaluation of Antimicrobial and Anti-Biofilm Formation Activities of Novel Poly(vinyl alcohol) Hydrogels Reinforced with Crosslinked Chitosan and Silver Nano-Particles.

Novel hydrogels were prepared by blending chitosan and poly(vinyl alcohol), PVA, then crosslinking the resulting blends using trimellitic anhydride isothiocyanate at a concentration based on chitosan content in the blends. The weight ratios of chitosan: PVA in the blends were 1:3, 1:1, and 3:1 to produce three hydrogels symbolized as H13, H11, and H31, respectively. For a comparison, H10 was also prepared by crosslinking pure chitosan with trimellitic anhydride isothiocyanate. For further modification, three H31/silver nanocomposites (AgNPs) were synthesized using three different concentrations of silver nitrate to obtain H31/AgNPs1%, H31/AgNPs3% and H31/AgNPs5%. The structures of the prepared samples were emphasized using various analytical techniques. PVA has no inhibition activity against the tested microbes and biofilms. The antimicrobial and anti-biofilm formation activities of the investigated samples was arranged as: H31/AgNPs5% ≥ H31/AgNPs3% > H31/AgNPs1% > H10 > H31 > H11 > H13 > chitosan. H31/AgNPs5% and H31/AgNPs3% were more potent than Vancomycin and Amphotericin B against most of the tested microbes. Interestingly, H31 and H31/AgNPs3% were safe on the normal human cells. Consequently, hydrogels resulting from crosslinked blends of chitosan and PVA loaded with AgNPs in the same structure have significantly reinforced the antimicrobial and inhibition activity against the biofilms of PVA.

Fabrication of a biogenic Inorganic-Organic hybrid composite Adsorbent: Optimization and Physico-chemical studies

Fabrication of an advanced biogenic adsorbent material is a pre-requisite for the development of a protocol for safe and cost-effective removal of pharmaceuticals from wastewater. With increasing improvements in health care via medication, incidences of trace levels of pharmaceuticals are making their presence in water bodies. Such emerging contaminants cause toxic effects to aquatic biota. Chitosan (CT) and hydroxyapatite (HAP) have demonstrated good adsorption potential, but each have their own limitations; thereby restricting their widespread usage in wastewater treatment. Composites are known to exhibit mechanical stability and hold tremendous potential of enhanced removal efficiency for diverse types of contaminants. With this hypothesis, and with an aim to fabricate a biogenic advanced adsorbent, various nanocomposites were fabricated using different weight ratios of CT, HAP and magnetite (MNP). Selection of the best adsorbent was made based on their batch adsorptive performance (conducted under identical operating conditions) for a model pharmaceutical viz. ciprofloxacin (CF) from simulated wastewater. Studies revealed the better adsorption potential of the NCs as compared to either CT or HAP. Also, the highest adsorption capacity (516.98 µg/g) was demonstrated by the nanocomposite (NC1) fabricated using HAP, CT and MNP in the weight ratio of 1:2:1. Physico-chemical studies (FTIR, EDX, Fe-SEM and TEM) concluded the successful fabrication of the nanocomposite and further revealed discrete/monodispersed spherical shaped nano-sized particles, and presence of surface functionalities corresponding to HAP, CT and MNP.

Cytocompatible drug delivery hydrogels based on carboxymethylagarose/chitosan pH-responsive polyelectrolyte complexes

Several drugs are chemically unstable in the gastric environment and have low bioavailability restricted by intestinal absorption, which motivates the development of alternative routes for drug release, such as transdermal drug carriers for drug delivery to specific areas of the skin. Herein, novel polyelectrolyte complexes (PEC) consisting of carboxymethylagarose (CMA) and chitosan (CS) were prepared. pH-responsive CMA/CS hydrogels were obtained by mixing CMA and CS at various weight ratios. Swelling ratio was modulated by varying the CMA and CS weight ratio, and the highest swelling values were achieved for 2:1 wt% hydrogels at 25 °C and pH 6.0. PEC films were characterized by ATR-FTIR spectroscopy, TGA, DSC, and SEM. Results indicated that CMA and CS were successfully crosslinked by ionic complexation. As a model drug, diclofenac sodium (DS) was loaded in CMA/CS PECs. Association efficiency and loading capacity were ca. 69% and 79%, respectively, exhibiting 67% cumulative release after 72 h at 37 °C and pH 6.0 through Fickian diffusion mechanism. Viability assay of immortalized human keratinocyte (HaCat) cells showed ca. 100% survival in the presence of hydrogels and DS. Therefore, this work suggests that CMA/CS PECs can be applied as pH-responsive carriers for dermal drug delivery.

Formulation and optimization of lemon balm extract loaded azelaic acid-chitosan nanoparticles for antibacterial applications

Herein, preparation of chitosan/azelaic acid (CsAz) nanoparticles, loaded with lemon balm extract (LBE), and optimization of the formulation by using a mathematical model is reported. The model was designed by experimental design technique (DOE) to evaluate the effect of weight ratio of chitosan to azelaic acid (Cs/Az), tripolyphosphate (TPP) concentration and LBE weight on the loading efficiency of lemon balm in the chitosan nanoparticles. Data analysis from DOE indicated that the Cs/Az ratio (p-value 0.3014) exhibited no significant effect on the loading efficiency. Meanwhile, TPP concentration (p-values 0.0021) and LBE weight (p-value <0.0001) showed dominant and significant influences on the loading efficiency, respectively. Results demonstrated that the loading efficiency decreased by increasing LBE weight and TPP concentration. The optimum formulation to get maximum value of loading efficiency was determined as 2 (wt/wt) Cs/Az, 0.10 mg/ml TPP concentration and 68.5 mg LBE weight. The antimicrobial activity of the optimum sample was evaluated on 9 different species of gram-positive/gram-negative bacteria and 1 species of fungi. Results showed that a synergistic effect was observed between azelaic acid and LBE. In some cases, such as Enterococcus faecalis (ATCC 19433), the formulated system exhibited a better performance compared with neat azelaic acid or gentamicin. Finally, it is concluded that CsAz nanoparticles could be applied as potent and green antiseptic agent.

Effect of chitosan on membrane formation and processability of bamboo dissolving pulp based ultrafiltration membrane

Bamboo dissolving pulp (BP)/chitosan (CS) blend solutions were obtained by adding different weight ratios of BP and CS particles to N-methyl-morpholine-N-oxide (NMMO) solvent. The processing and membrane-forming performances of the blend solutions were studied using a rotating rheometer. The BP/CS blend solutions’ optimal processing temperature was 50 to 70 °C. When the CS weight ratio was 9.09 wt%, the viscosity of the solution decreased, which was conducive to the processing of the membrane. The BP/CS blend ultrafiltration membranes were prepared by phase transformation of the blend solutions. The results showed that the rejection rate of the BP/CS blend ultrafiltration membrane with physically added CS particles was greatly improved compared with that of the regenerated BP ultrafiltration membrane.

Enhanced physical and antimicrobial properties of alginate/chitosan composite aerogels based on electrostatic interactions and noncovalent crosslinking

In this study, the alginate/chitosan composite aerogels based on electrostatic interactions and noncovalent crosslinking were fabricated using sol-gel method followed by freeze-drying process. The solution property results showed that with the addition of chitosan in alginate solution, a tighter network was induced by the more entangled molecular chains. The aerogel morphology observations showed that the pore diameter decreased with the increasing weight ratio of chitosan in the aerogels, but was even much lower after the crosslinking of excess alginate with calcium ions. After crosslinking, the aerogels presented the improved thermal stability and higher mechanical properties, as well as stronger antibacterial activities against Staphylococcus aureus and Escherichia coli. Therefore, the enhanced physical and antimicrobial properties of the alginate/chitosan aerogels may be achieved by modulation of electrostatic interactions and noncovalent crosslinking, suggesting the promising applications of these composite aerogels as active food packaging materials for antimicrobial purpose.

Encapsulation of ginger essential oil in chitosan‐based microparticles with improved biological activity and controlled release properties

The objective of the present work was to encapsulate ginger essential oil (GEO) into chitosan-based microparticles (CMPs) using the ionic gelation method. The fabricated microparticles showed a particle size range of 342–531 nm with a zeta potential of 23.4–45.4 mV. Fourier-transform infrared (FTIR) analysis confirmed a successful encapsulation without any chemical alteration of GEO. The maximum encapsulation efficiency (31.18 ± 0.94) was obtained for the sample with essential oil to chitosan ratio of 25%. The optimal weight ratio of chitosan to ginger was found to be 1:0.5. In vitro release test revealed that the greatest release of GEO (78.11%) occurred in an acidic medium. It also was found that the thermal stability and antioxidant capacity of GEO improved considerably by encapsulation. Practical applications Considering the high antioxidant activity and thermal stability of GEO-loaded CMPs, they can be used as a valuable additive in the food industry to extend the shelf life and preserve the quality of foods.

Titania/chitosan-lignin nanocomposite as an efficient photocatalyst for the selective oxidation of benzyl alcohol under UV and visible light.

Developing functional materials from biomass is a significant research subject due to its unique structure, abundant availability, biodegradability and low cost. A series of chitosan–lignin (CL) composites were prepared through a hydrothermal method by varying the weight ratio of chitosan and lignin. Subsequently, these CL composites were combined with titania (T) to form a nanocomposite (T/CL) using sol–gel and hydrothermal based methods. T/CL nanocomposites exhibited improved photocatalytic performance in comparison with sol–gel and hydrothermally prepared pristine titania (SGH-TiO2), towards the selective oxidation of benzyl alcohol (BnOH) to benzaldehyde (Bnald) under UV (375 nm) and visible light (515 nm). More specifically, the 75T/CL(25 : 75) nanocomposite (a representative photocatalyst from the 75T/CL nanocomposite series) showed very high selectivity (94%) towards Bnald at 55% BnOH conversion under UV light. Whereas, SGH-TiO2 titania exhibited much lower (68%) selectivity for Bnald at similar BnOH conversion. Moreover, the 75T/CL(25 : 75) nanocomposite also showed excellent Bnald selectivity (100%) at moderate BnOH conversion (19%) under visible light. Whereas, SGH-TiO2 did not show any activity for BnOH oxidation under visible light. XPS studies suggest that the visible light activity of the 75T/CL(25 : 75) nanocomposite is possibly related to the doping of nitrogen into titania from chitosan. However, according to UV-visible-DRS results, no direct evidence pertaining to the decrease in band-gap energy of titania was found upon coupling with the CL composite and the visible light activity was attributed to N-doping of titania. Overall, it was found that T/CL nanocomposites enhanced the photocatalytic performance of titania via improved light harvesting and higher selectivity through mediation of active radical species.

PREPARATION AND CHARACTERIZATION OF CHITOSAN-AGAR FILMS

Hydrogel films composed of chitosan and agar or chitosan, agar and honey/bee pollen were prepared; they could be used as active wound dressings. During this study, various types of gel films were prepared using chitosan with different molecular weights and ratios of the two biopolymers. In addition, compositions with different amounts of honey or bee pollen were obtained. The selected samples were characterized by determining typical properties that are important for wound dressings. The best twocomponent films had a chitosan to agar weight ratio of 2:1. From among the examined tri-component films, the 2:1:0.5 weight ratio of chitosan, agar and 50 wt% honey solution was the best composition.