Surface functionalization of plasticized chitosan films through PNIPAM grafting via UV and plasma graft polymerization

Dielectric barrier discharge plasma-modified chitosan flocculant and its flocculation performance

The flocculation performance of chitosan can be enhanced by grafting modification to overcome its disadvantages of poor water solubility. In this study, chitosan was modified by dielectric barrier discharge plasma and polymerized with acrylamide and aluminum chloride to synthesize a new chitosan-based flocculant, namely, chitosan-acrylamide-aluminum chloride (CA-PAC). After optimizing the synthesis conditions of CA-PAC, the best conditions were as follows: discharge time of 3 min, discharge power of 50 W, polymerization temperature of 60 °C, polymerization time of 3 h, total monomer concentration of 100 g/L, and m(AlCl3):m(CA) ratio of 2:1. Characterization was performed through SEM, XPS, FTIR, XRD, TG and 1H NMR. Results showed that the preparation of CA-PAC was successful. The influences of flocculant dosage, pH, and stirring intensity on flocculation efficiency were investigated. The removal efficiency of turbidity was 94.1 %. The investigation of the flocculation mechanism revealed that CA-PAC mainly relied on charge neutralization or the synergic action of electric neutralization, bridging, and roll-sweep under acidic and neutral conditions, but it depended on the joint action of adsorption bridging and net sweeping under alkaline conditions. This study provides new ideas for the preparation and development of modified chitosan and broadens its application in water treatment.

Chemical modifications in the structure of marine polysaccharide as serviceable food processing and preservation assistant: A review

Marine polysaccharides are a kind of natural polysaccharides which isolated and extracted from marine organisms. Now some marine polysaccharides, such as chitosan, sodium alginate and agar, have been proven to exhibit antibacterial, antioxidant functions and biocompatibility, which are often used to preserve food or improve the physicochemical properties of food. However, they still have the defects of unsatisfactory preservation effect and biological activity, which can be remedied by its modification. Chemical modification is the most effective of all modification methods. The advances in common chemical modification methods of chitosan, sodium alginate, agar and other marine polysaccharides and research progress of modified products in food processing and preservation were summarized, and the influence of additional reaction conditions on the existence of chemical modification sites of polysaccharides was discussed. The modification of functional groups in natural marine polysaccharides leads to the change of molecular structure, which can improve the physical, chemical and biological properties of marine polysaccharides. Chemically modified products have been used in various fields of food applications, such as food preservatives, food additives, food packaging, and food processing aids. In general, chemical modification has excellent potential for food processing and preservation, which can improve the function of marine polysaccharides.

Novel linezolid loaded bio-composite films as dressings for effective wound healing: experimental design, development, optimization, and antimicrobial activity

Biphasic release bio-composite films of the low water-soluble drug, linezolid (LNZ), were formulated using the solvent casting technique. Different polymers and plasticizers (gelatin, Tween 80, polyethylene glycol 400, and glycerol) were assessed for the preparation of bio-composite films. An I-optimal design was applied for the optimization and to study the impact of polymer concentration (X₁), plasticizer concentration (X₂), polymer type (X₃), and plasticizer type (X₄) on different LNZ-loaded bio-composite films. The film thickness, moisture content, mechanical properties, swelling index, and percentage of drug release at fixed times opted as dependent variables. Results demonstrated a significant effect of all independent variables on the drug release from the prepared bio-composite films. The plasticizer concentration significantly increased the thickness, moisture content, elongation at break, swelling index, and in vitro drug release and significantly reduced the tensile strength. The optimized LNZ-loaded bio-composite film comprised of 15% Tween 80 and 30% PEG 400 was highly swellable, elastic, acceptable tensile properties, safe, maintained a moist environment, and indicated great antimicrobial activity against both Staphylococcus aureus (ATCC^® 25922) and methicillin-resistant Staphylococcus aureus (MRSA), which are common wound infectious bacteria. The present study concludes that the optimized LNZ-loaded bio-composite film was successfully designed with fast drug release kinetics and it could be regarded as a promising novel antimicrobial wound dressing formulation.

Production and Characterization of a Coconut Oil Incorporated Gelatin-Based Film and Its Potential Biomedical Application

The influence of coconut oil (CO) on a gelatin-based film was investigated when used as a potential wound dressing material. There is limited study on CO in protein-based wound dressing materials. Therefore, in this study a self-supporting, continuous and homogenous CO incorporated gelatin-based film was formulated and obtained by solution casting method. The influence of CO on physicochemical and thermal properties of gelatin-based film was also determined. Moreover, the effect CO in gelatin films on cell viability and cell migration was analysed with a preliminary cell culture study. Homogenous dispersion of 10% (w/w) CO was obtained in films when 3% (v/w) Tween 80, a surfactant, was incorporated to 20% (w/w) plasticized gelatin film forming solution. Effect of CO on gelatin-based film was observed via phase separation by SEM analysis. Water uptake of gelatin film with no CO, GE film; and 10% (w/w) CO incorporated GE film, GE-CO, were 320% and 210%, respectively, after 3 hours in water. FTIR analysis showed triglyceride component of CO and increased hydrogen bonding between NH groups of gelatin in GE-CO films. DSC results suggested a more ordered structure of GE-CO film due to an increase in melt-like transition temperature and melting enthalpy of GE-CO film. CO content also increased cell viability, assessed by XTT Assay since cell viability was approximately 100% when L929 cell culture was incubated with GE-CO of 5-100 μg/mL. Moreover, GE-CO samples within 5-25 μg/mL concentration range, increased proliferation of L929 cells since cell viability was significantly higher than the 100% viable cell culture control (P < 0.05) which is also an indication of efficient healing. However, GE decreased viability of L929 cells significantly at 100-10 μg/mL concentration range (P < 0.05) and were toxic at concentrations of 100, 75 and 50 μg/mL which decreased ∿50% of the viability of the cells. Scratch Assay to assess in vitro wound healing showed cell migration towards scratch after 24 h as an indication of wound healing only in GE-CO samples. This study showed that, CO could efficiently be added to gelatin-based films for preparation of a primary wound dressing biomaterial which is also demonstrated to have a promising wound healing effect for minor wounds.

Polymer-Based Scaffolds Loaded with Aloe vera Extract for the Treatment of Wounds

The treatment of wounds is one challenging biomedical field due to delayed wound healing common in chronic wounds. Several factors delay wound healing, including microbial infections, malnutrition, underlying physiological conditions, etc. Most of the currently used wound dressing materials suffer from poor antimicrobial properties, poor biodegradability and biocompatibility, and weak mechanical performance. Plant extracts, such as Aloe vera, have attracted significant attention in wound management because of their interesting biological properties. Aloe vera is composed of essential constituents beneficial for the wound healing process, such as amino acids, vitamins C and E, and zinc. Aloe vera influences numerous factors that are involved in wound healing and stimulates accelerated healing. This review reports the therapeutic outcomes of aloe vera extract-loaded polymer-based scaffolds in wound management.

Using Specified Risk Materials-Based Peptides for Oil Sands Fluid Fine Tailings Management

Fluid fine tailings are produced in huge quantities by Canada's mined oil sands industry. Due to the high colloidal stability of the contained fine solids, settling of fluid fine tailings can take hundreds of years, making the entrapped water unavailable and posing challenges to public health and the environment. This study focuses on developing value-added aggregation agents from specified risk materials (SRM), a waste protein stream from slaughterhouse industries, to achieve an improved separation of fluid fine tailings into free water and solids. Settling results using synthetic kaolinite slurries demonstrated that, though not as effective as hydrolyzed polyacrylamide, a commercial flocculant, the use of SRM-derived peptides enabled a 2-3-fold faster initial settling rate than the blank control. The pH of synthetic kaolinite tailings was observed to be slightly reduced with increasing peptides dosage in the test range (10-50 kg/ton). The experiments on diluted fluid fine tailings (as a representation of real oil sands tailings) demonstrated an optimum peptides dosage of 14 kg/ton, which resulted in a 4-fold faster initial settling rate compared to the untreated tailings. Overall, this study demonstrates the novelty and feasibility of using SRM-peptides to address intractable oil sands fluid tailings.

Covalent Immobilization of Polypeptides on Polylactic Acid Films and Their Application to Fresh Beef Preservation

To enhance the advantage of a long-term stability and low-toxicity active packaging system, two biodegradable covalent immobilized antibacterial packaging films were developed and applied to fresh beef preservation in this study. A polylactic acid (PLA) film was prepared by the extrusion-casting method. The surface of the PLA film was modified with plasma treatment to generate carboxylic acid groups, and then antibacterial agent nisin or ε-poly lysine (ε-PL) was covalently attached to the modified film surface. Physical, chemical, and antimicrobial properties of films were then characterized. Scanning electron microscopy and water contact angle images confirmed that nisin or ε-PL was successfully grafted onto the film surface. The values of protein loading on the nisin-g-PLA film and ε-PL-g-PLA film were 5.34 ± 0.26 and 3.04 ± 0.25 μg of protein/cm² on the surface. Microbial analysis indicated that the grafted films effectively inhibit the growth of bacteria. Finally, the effects of the nisin-g-PLA film or ε-PL-g-PLA film on physicochemical changes and microbiological counts of fresh beef during cold storage at 4 °C were investigated. The total viable count of the control sample exceeded 7 logarithms of the number of colony forming units per gram (log CFU/g) after 11 days of cold storage (7.01 ± 0.14 log CFU/g) versus 15 days for the ε-PL-g-PLA film (7.37 ± 0.06 log CFU/g) and the nisin-g-PLA film (6.83 ± 0.10 log CFU/g). The results showed that covalent immobilized antibacterial packaging films had positive impacts on the shelf life and quality of fresh beef. Therefore, a covalent immobilized antibacterial packaging system could be a novel preservative method for foods.