A review study on green synthesis of chitosan derived schiff bases and their applications.

Chitosan is a bio-degradable, bio-compatible, non-toxic, and renewable biopolymer. The reactive amino group of chitosan has gained importance because using these amino groups can help achieve the different types of structural modification in chitosan. Chemical modification of chitosan via imine functionalization results in the formation of a chitosan Schiff base. The present review covers the green synthesis of chitosan Schiff bases using non-conventional green methods such as microwave irradiation, green solvent, ultrasound irradiation, and one-pot synthesis. These methods are energy-efficient and greener versions of the conventional condensation methods. Scientists have paid significant attention to the chitosan Schiff base because of its unique properties and versatility. These molecules display various biological applications, including antioxidant, antimicrobial, anticancer, antibacterial, and anti-fungal. In addition to biological applications, chitosan Schiff base also has other applications like corrosion inhibition, catalysis, metal ion adsorption, and as a sensor. Available literature particularly shows the different methods for the synthesis of chitosan Schiff bases and their different applications. This review gives detailed insight regarding sustainable approaches to the synthesis of chitosan derived Schiff bases and their applications in various emerging fields.

Vanillin cross-linked chitosan/gelatin bio-polymer film with antioxidant, water resistance and ultraviolet-proof properties.

Cross-linking is the most promising method for preparing high-performance chitosan/gelatin bio-polymer film. In this work, vanillin cross-linked chitosan/gelatin bio-polymer (CGGV) film with good mechanics, water resistance, antioxidant and ultraviolet-proof property was prepared. The micro-structure, physical and functional properties of CGGV film were studied. Results showed that vanillin as a cross-linking agent provided a compact inner micro-structure through Schiff base and hydrogen bond interaction. Moderate cross-linking significantly improved mechanical strength, thermal ability, hydrophobicity of the films and reduced the water vapor permeability, swelling ratio and water solubility. Especially, CGGV films showed stronger ultraviolet-proof properties and possessed potent radical scavenging activity. Therefore, CGGV film is suitable to protect per-mature fruits and could be used as novel multifunctional packaging in the agriculture and foods industry.

Coir fiber as thermal insulator and its performance as reinforcing material in biocomposite production.

Coir is a lignocellulosic natural fiber derived from the coconut's husk, an abundantly found fruit or nut worldwide. This fiber has some unique characteristics, such as its resistance to seawater, microbial attack, high impact, etc. But its low thermal conductivity or high thermal insulating property makes it suitable for being used as insulators in civil engineering sites. On the other hand, the sustainability of a material depends heavily on its environmental impact of the material. For making sustainable materials like biocomposite, there are no options other than using polymers derived from natural renewable sources. Polylactic acid(PLA) is an example of those types of material. And these materials are often being reinforced by fibers like coir for various reasons including improving mechanical properties, reducing the cost of the material, and improving the material's sustainability. Many coir-reinforced sustainable biopolymer composites have already been produced in many pieces of research, which will be discussed in this paper, along with the chemical and physical structure of coir fiber. In addition, this paper will try to focus on the insulating properties of coir and coir-reinforced composites while will also compare some properties of the composites with some commonly used materials based on different parameters to show the suitability of using the coir fiber in heat-insulating applications and to produce sustainable biocomposite materials.

A review on super-wettable porous membranes and materials based on bio-polymeric chitosan for oil-water separation.

Appropriate surface wettability of membranes and materials are of an extreme importance for targeting separation of mixtures/emulsions such as oil from water or conversely water from oil. The development of super-wettable membranes and materials surfaces have shown remarkable potential for recovering water from oil-water emulsion while offering maximum resistance to fouling. The availability of clean and potable water has been regarded as an important global challenge for coming human generations. Oil and gas industry is continuously producing immense quantities of waste stream regarded as produced water which contains oil dispersed in water along with other several components. Treating such immense quantities of oily wastewater is of utmost need for recovering precious water for possible reuse or safe disposal. Various technologies have been developed for targeting the separation of oil-water emulsions or mixtures to harness useful potable water and oil as products. Membrane-based separations or use of porous materials such as mesh have been explored in literature for separation of oil-water mixtures/emulsions. Given the unique features of special hydrophilicity, ease of tunability, control of molecular weight, abundant availability, and potential for commercial scale up, chitosan has been extensively used for modifying membranes/meshes or preparing composites with other materials for oil-water separations. This review has described in detail the synthesis, methods of modification and application of chitosan-based super-wettable membranes/meshes and porous materials for oil-water separation. The special wettability features including super-hydrophobicity/superoleophilicity, super-oleophobicity/super-hydrophilicity and super-hydrophilicity/underwater super-oleophobicity of various chitosan-based membranes and materials have been discussed in detail in the review. The strategies for enhancing or developing special wettability for target specific applications have also been discussed. Finally, the challenges, their respective importance have been identified along with a discussion on possible solutions to these challenges.

A comprehensive review on the recent advancements in natural rubber nanocomposites.

Natural rubber (NR) is an eminent sustainable material and is the only agricultural product among various rubbers. Use of nanofillers in NR matrix as a reinforcing agent has gained huge attention because they offer excellent matrix-filler interaction upon forming a good dispersion in the NR matrix. Nanoscale dispersion of fillers lead to greater interfacial interactions between NR and fillers compared to microfillers, which in turn lead to a conspicuous reinforcing effect. Addition of various nanofillers into NR matrix improves not only the mechanical properties but also the electrical, thermal and antimicrobial properties to an extreme level. The current review describes the reinforcing ability of various nanofillers such as clay, graphene, carbon nanotube (CNT), titanium dioxide (TiO2), chitin, cellulose, barium titanate (BaTiO3) and lignin in NR matrix. Moreover, reinforcement of various hybrid nanofillers in NR is also discussed in a comprehensive manner. The review also includes the historical trajectory of rubber nanocomposites and a comprehensive account on the factors affecting the properties of the NR nanocomposites.

Composite Polymers from Leather Waste to Produce Smart Fertilizers.

The leather industry is facing important environmental issues related to waste disposal. The waste generated during the tanning process is an important resource of protein (mainly collagen) which can be extracted and reused in different applications (e.g., medical, agricultural, leather industry). On the other side, the utilization of chemical fertilizers must be decreased because of the negative effects associated to an extensive use of conventional chemical fertilizers. This review presents current research trends, challenges and future perspectives with respect to the use of hide waste to produce composite polymers that are further transformed in smart fertilizers. Hide waste contains mostly protein (collagen that is a natural polymer), that is extracted to be used in the cross-linking with water soluble copolymers to obtain the hydrogels which are further valorised as smart fertilizers. Smart fertilizers are a new class of fertilizers which allow the controlled release of the nutrients in synchronization with the plant's demands. Characteristics of hide and leather wastes are pointed out. The fabrication methods of smart fertilizers and the mechanisms for the nutrients release are extensively discussed. This novel method is in agreement with the circular economy concepts and solves, on one side, the problem of hide waste disposal, and on the other side produces smart fertilizers that can successfully replace conventional chemical fertilizers.

Generation of non-toxic, chemical functional bio-polymer for desalination, metal removal and antibacterial activities from animal meat by-product.

The meat industry produces a lot of waste, which contains large amounts of the organics and nutrients. Animal by-products have potential for biomaterial extraction. The use of bio-material, which can be obtained from plant sources, microorganisms, agricultural, and animal waste are nowadays favored because of their compatible, cost-effective, and low-risk for removal of pollutants, compared to chemical and physical methods. In this study, a biopolymer from meat by-product extracted by methanol-chloroform and characterized by FTIR, GC-MS, HPLC, and SDS-PAGE analyzes. The extracted biomaterial was useful in water desalination by calcium carbonate precipitation and heavy metals removal, which was confirmed by FTIR and ICP analyzes. The extracted biomaterial also has antibacterial properties against Pseudomonas aeruginosa and Escherichia coli without toxicity to human blood cells, which can make it useful in industries such as its application in fish ponds.

Silkworm and spider silk electrospinning: a review.

Issues of fossil fuel and plastic pollution are shifting public demand toward biopolymer-based textiles. For instance, silk, which has been traditionally used during at least 5 milleniums in China, is re-emerging in research and industry with the development of high-tech spinning methods. Various arthropods, e.g. insects and arachnids, produce silky proteinic fiber of unique properties such as resistance, elasticity, stickiness and toughness, that show huge potential for biomaterial applications. Compared to synthetic analogs, silk presents advantages of low density, degradability and versatility. Electrospinning allows the creation of nonwoven mats whose pore size and structure show unprecedented characteristics at the nanometric scale, versus classical weaving methods or modern techniques such as melt blowing. Electrospinning has recently allowed to produce silk scaffolds, with applications in regenerative medicine, drug delivery, depollution and filtration. Here we review silk production by the spinning apparatus of the silkworm Bombyx mori and the spiders Aranea diadematus and Nephila Clavipes. We present the biotechnological procedures to get silk proteins, and the preparation of a spinning dope for electrospinning. We discuss silk's mechanical properties in mats obtained from pure polymer dope and multi-composites. This review highlights the similarity between two very different yarn spinning techniques: biological and electrospinning processes.

Chitosan as a machine for biomolecule delivery: A review.

The major role of biomolecules in treatment of different diseases has been proven by several studies. However, the main drawback in successful treatment by these molecules is designing of efficient delivery systems to fulfill all of the delivery purposes. In this regard, many polymeric vehicles have been introduced for protecting and delivery of biomolecules to the target site. Chitosan as a unique biopolymer with special properties has been widely used for biomolecule delivery. Several research groups have focused on developing and applying of chitosan as a versatile machine in biomolecule delivery. In this review the unique properties of chitosan have been discussed at first and then its application as a delivery machine for different types of biomolecules include protein and peptides, nucleic acids and vaccines has been considered. Furthermore, the targeting approach by conjugation of various ligands to the chitosan and also the current challenges for development of chitosan vehicles will be discussed for biomolecule delivery.

Abrasive Sensitivity of Engineering Polymers and a Bio-Composite under Different Abrasive Conditions.

Two different test systems were designed to evaluate the tribological behavior of five engineering plastics (Polyamide-PA grades and Ultra High Molecular Weight Polyethylene-UHMW-PE) and a fully degradable bio-composite (Polylactic Acid-PLA/hemp fibers) targeted to agricultural machinery abrasive conditions. Pin-on-plate tests were performed with different loads, sliding velocity and abrasive particles. The material response was further investigated in a slurry containing abrasive test system with different sliding velocities and distances, abrasive media compositions and impact angles. The abrasive wear, the change of the 3D surface roughness parameters, the friction force and contact temperature evolution were also analyzed as a function of the materials' mechanical properties (H,E,σy,σc,εB,σF,σM) and the dimensionless numbers derived from them. Using the IBM SPSS 25 software, multiple linear regression models were used to statistically evaluate the measured data and to examine the sensitivity of the material properties and test system characteristics on the tribological behavior. For both test setups, the system and material characteristics influencing the dependent variables (wear, friction, heat generation) and the dimensionless numbers formed from the material properties were ranked using standardized regression coefficients derived from the regression models. The abrasion sensitivity of the tested materials were evaluated taking into account a wide range of influencing parameters.

Silk fibroin as a natural polymeric based bio-material for tissue engineering and drug delivery systems-A review.

The silk fibroin (SF) prepared by Bombyx mori silkworms is one of the mainly abundant natural fiber and can be obtained simply and economically. SF as bio-material has superior bio-compatibility and bio-degradability. The current review provides an inclusive outline of up to date and novel developments on SF as bio-material based applications in tissue engineering and various drug delivery. SF as bio-materials was comprehensively reviewed, demonstrating the characteristics and applications of SF bio-materials in tissue engineering and drug delivery systems. Convenient regeneration, superb bio-compatibility, significant mechanical properties and versatile bio-degradability of SF has been investigated for the preparation of a range of articles such as films, spongy matrices, hydrogels, etc., and has been examined for use in a choice of tissue engineering utilization. Also, SF nanoparticles have been effectively designed and are competent to manage the release rate of biomolecules in a continuous approach with high stability. Therefore, the present review comprehensively covered the advancement made on SF based drug delivery, in vitro engineering and rejuvenation determines possibilities for additional progress in these areas.

(Bio)polymer/ZnO Nanocomposites for Packaging Applications: A Review of Gas Barrier and Mechanical Properties.

Nanotechnology is playing a pivotal role in improving quality of life due to its versatile applications in many areas of research. In this regard, nanoparticles have gained significant importance. Zinc oxide nanoparticles (ZnO NPs) amongst other nanoparticles are being used in producing nanocomposites. Methods like solvent casting, solution casting, solvent volatilization, twin-screw extrusion, melt compounding and extrusion blow molding have been applied to produce ZnO NPs based (bio)polymer composites. These composites are of great interest in the research area of food packaging materials due to their improved multifunctional characteristics like their mechanical, barrier and antimicrobial properties. This paper gives an overview of the main methods to synthesize ZnO NPs, methods to incorporate ZnO NPs in (bio)polymers, and finally, the gas barrier and mechanical properties of the nanocomposites. As a conclusion, a maximum decline in oxygen, carbon dioxide and water vapor permeability was reported as 66%, 17% and 38% respectively, while tensile strength and young's modulus were observed to increase by 32% and 57% respectively, for different (bio)polymer/ZnO nanocomposites.

Recovery and utilization of collagen protein powder extracted from chromium leather scrap waste.

In this work, we investigate collagen protein powder (CPP) extracted from chromium leather scrap waste (CLSW). The composition and molecular weight distribution of CPP were determined by elemental analysis and sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE), respectively. The microstructure and size distribution of CPP were then characterized by scanning electron microscopy (SEM) and nanometer analyzer instrument. Finally, CPP was treated with corn starch (CS), and the swelling behavior of the resulting CPP-CS blend was investigated in order to determine its range of applications. The experimental data showed that CPP contains 13 different amino-acids. CPP also displayed low mineral salt levels and a nitrogen content of 43.84%, indicating its potential use as an organic fertilizer. The molecular weight range of CPP is 6.5 to ~ 26.6 kDa. After the obtained CPP was blended with CS, the CPP-CS blend is endowed with optimal swelling properties and is able to overcome the solubility drawbacks of CPP alone. In addition, when the CPP was used as a natural fertilizer, the germination rate and height of kidney beans obviously increased.

Poly Organotin Acetates against DNA with Possible Implementation on Human Breast Cancer.

Two known tin-based polymers of formula {[R3Sn(CH3COO)]n} where R = n-Bu⁻ (1) and R = Ph⁻ (2),were evaluated for their in vitro biological properties. The compounds were characterized via their physical properties and FT-IR, 119Sn Mössbauer, and ¹H NMR spectroscopic data. The molecular structures were confirmed by single-crystal X-Ray diffraction crystallography. The geometry around the tin(IV) ion is trigonal bi-pyramidal. Variations in O⁻Sn⁻O···Sn' torsion angles lead to zig-zag and helical supramolecular assemblies for 1 and 2, respectively. The in vitro cell viability against human breast adenocarcinoma cancer cell lines: MCF-7 positive to estrogens receptors (ERs) and MDA-MB-231 negative to ERs upon their incubation with 1 and 2 was investigated. Their toxicity has been studied against normal human fetal lung fibroblast cells (MRC-5). Compounds 1 and 2 exhibit 134 and 223-fold respectively stronger antiproliferative activity against MDA-MB-231 than cisplatin. The type of the cell death caused by 1 or 2 was also determined using flow cytometry assay. The binding affinity of 1 and 2 towards the CT-DNA was suspected from the differentiation of the viscosity which occurred in the solution containing increasing amounts of 1 and 2. Changes in fluorescent emission light of Ethidium bromide (EB) in the presence of DNA confirmed the intercalation mode of interactions into DNA of both complexes 1 and 2 which have been ascertained from viscosity measurements. The corresponding apparent binding constants (Kapp) of 1 and 2 towards CT-DNA calculated through fluorescence spectra are 4.9 × 104 (1) and 7.3 × 104 (2) M-1 respectively. Finally, the type of DNA binding interactions with 1 and 2 was confirmed by docking studies.

Silk Fibroin Based Drug Delivery Applications: Promises and Challenges.

BACKGROUND: Silk Fibroin (SF), a natural source material obtained from Bombyx mori, has been widely enlisted as biomaterial having outstanding mechanical properties. SF has been reported as one of the propitious bio-polymers for various drug delivery systems, as well as drug delivery vehicle. OBJECTIVE: This review is a summary of comprehensive applications of silk fibroin in various drug delivery systems, and also to present the current opportunities and requirements by furnishing a definitive assessment on silk fibroin as a polymer. RESULTS: SF has been reported as one of the propitious bio-polymers for various drug delivery systems, as well as drug delivery vehicle. SF is inestimable owing to its non-toxic and non-antigenic character, except for the firmness formation whilst being stored at lower temperature. Unlike other polymeric biomaterials, SF is regenerated in aqueous systems in defined temperature, pressure and pH, which is one of its major advantages in formulation. SF nanoparticles are also used to deliver proteins and peptides. Recently, SF has been used to deliver anti-cancer agents like paclitaxel, doxorubicin, floxuridine, and methotrexate, and including the natural product curcumin, has shown to elicit significant biological activity when compared to their conventional form. Interestingly, SF has shown to be a promising biomaterial for implantables and injectable drug delivery applications. CONCLUSION: In the present review, we have summarized the physical and chemical properties, biocompatibility and non-immunogenic characters of SF and its applications in various drug delivery systems.

Effect of guar gum and salt concentrations on drag reduction and shear degradation properties of turbulent flow of water in a pipe.

Concentrated solutions of guar gum in water (1000-3000ppm) with and without KCl salt (1000-4000ppm) were injected near the wall for a short period (2.5min) to investigate their effect on drag reduction in turbulent flow of water through a pipe (Re≈17000-45000). Relative to bulk solution, the concentrations of polymer and salt were 50-150ppm and 50-200ppm, respectively. A drag reduction of 71.45% was observed for 3000ppm of biopolymer without salt. Guar gum experienced mechanical degradation under high shear conditions and addition of KCl improved shear stability up to 47% (for Re≈45000). A polymer concentration of 3000ppm and salt concentration of 2000ppm in the injection fluid were found to be optimum for achieving the highest drag reduction with better shear stability. Results indicated that boundary layer injection shows better drag reduction ability than pre-mixed solutions.

An overview of natural renewable bio-polymer lignin towards nano and biotechnological applications.

Lignin were said to be major bio-polymer next to cellulose which is an abundant biopolymer. This type of lignin was mostly isolated from woods which were named after their physical, morphological appearances and majorly on extracting sources. Still now there are very few reports on isolation, identification of pure lignin and isolating pathways are also not well defined. Molecular weight of lignin varies from thousands to ten thousands which are not explored accurately. Even-though lignins were surrounded by these many hurdles it has various application studies which were studied and reported. Nowadays researchers focused on synthesizing lignin nanoparticles which were subjected for various application studies in day today life. This lignin contains wide range of applications in several fields like medicinal, industrial, pharmaceuticals, etc., Most of the researcher are focused on applications like anti-oxidant and microbicidal agents. So this review will comprises of outlook of bioprocessing lignin and its application focused on nanoparticles synthesis, anti-oxidant and microbicidal agents. This was the first review on renewable bio-polymer lignin with its bio-pharmaceutical and nanobiotechnological applications.

Role of Bio-Based Polymers on Improving Turbulent Flow Characteristics: Materials and Application.

The remarkable ability of polymeric additives to reduce the level of frictional drag significantly in turbulent flow, even under extremely low dilutions, is known as turbulent drag-reduction behavior. Several bio-polymers have been assessed as promising drag-reducing agents for the potential replacement of high molecular weight synthetic polymers to improve safety and ameliorate environmental concerns. This article reviews the recent advances regarding the impact of several bio-polymer additives on turbulent drag reduction in either pipe or rotating disk flow systems, and their potential applications in the petroleum, biomedical, and agricultural industries.

Using wastewater after lipid fermentation as substrate for bacterial cellulose production by Gluconacetobacter xylinus.

In this study, lipid fermentation wastewater (fermentation broth after separation with yeast biomass) with high Chemical Oxygen Demand (COD) value of 25,591 mg/L was used as substrate for bacterial cellulose (BC) production by Gluconacetobacter xylinus for the first time. After 5 days of fermentation, the highest BC yield (0.659 g/L) was obtained. Both monosaccharide and polysaccharides present in lipid fermentation wastewater could be utilized by G. xylinus simultaneously during fermentation. By this bioconversion, 30.0% of COD could be removed after 10 days of fermentation and the remaining wastewater could be used for further BC fermentation. The crystallinity of BC samples in lipid fermentation wastewater increased gradually during fermentation but overall the environment of lipid fermentation wastewater showed small influence on BC structure by comparison with that in traditional HS medium by using FE-SEM, FTIR, and XRD. By this work, the possibility of using lipid fermentation wastewater containing low value carbohydrate polymer (extracellular polysaccharides) for high value carbohydrate polymer (BC) production was proven.

An experimental study of bio-polymer composite film as a micro-skin autograft covering / 实用医学杂志

Objective To explore the promoting effects of bio-polymer composite film as a micro-skin auto-graft covering on wound healing. Methods The full thickness skin defect models were made on both sides of 30 experimental rabbits. Then, the rabbits were randomly divided into experimental group and control group. In the for-mer group, the side was covered with chitosan/glucomannan composite membrane and in the latter, the side cov-ered with acelluar porcine skin after micro-skin autograft. We obtained wound tissues at week 1 , 2, 3, 4 and 5 af-ter operation. The conditions of wound healing were observed, the rate of wound healing was calculated, HE stain-ing was made, and PCNA and CD31 were detected by immunohistochemistry. Results (1) During 2~4 weeks af-ter operation, the rate of wound healing in the experimental group was significantly higher than that of the control wound (P<0.01). (2) The amount of neutrophil in experimental group was less than that of the control after oper-ation. (3) During 1 ~ 2 weeks after operation, the expression of PCNA in the experimental group was higher than that of the control group (P < 0.01), but lower than the control wounds during 1 ~ 2 weeks after operation (P <0.01). (4) During 1 ~ 5 weeks after operation, the expression of CD31 in the experimental group was higher than that of the control group (P < 0.01). Conclusion Chitosan/glucan-mannan composite membrane as a micro-skin autograft covering may promote wound healing.