Morphology and miscibility of chitosan/soy protein blended membranes

Cloning, Expression, and Characterization of a Metalloprotease from Thermophilic Bacterium Streptomyces thermovulgaris

Proteases hydrolyze proteins and reduce them to smaller peptides or amino acids. Besides many biological processes, proteases play a crucial in different industrial applications. A 792 bp protease gene (nprB) from the thermophilic bacterium Streptomyces thermovulgaris was cloned and expressed in E. coli BL21 using pET 50b (+). Optimal recombinant protease expression was observed at 1 mM IPTG, 37 °C for 4 h. The resulting protease was observed in soluble form. The molecular mass estimated by SDS-PAGE and Western blot analysis of the protease (NprB) fused with His and Nus tag is ~70 KDa. The protease protein was purified by Ammonium sulfate precipitation and immobilized metal ion affinity chromatography. The optimum pH and temperature for protease activity using casein as substrate were 7.2 and 70 °C, respectively. The mature protease was active and retained 80% of its activity in a broad spectrum of pH 6-8 after 4 h of incubation. Also, the half-life of the protease at 70 °C was 4 h. EDTA (5 mM) completely inhibited the enzyme, proving the isolated protease was a metalloprotease. NprB activity was enhanced in the presence of Zn2+, Mn2+, Fe2+ and Ca2+, while Hg2+ and Ni2+ decreased its activity. Exposure to organic solvents did not affect the protease activity. The recombinant protease was stable in the presence of 10% organic solvents and surfactants. Further characterization showed that zinc-metalloprotease is promising for the detergent, laundry, leather, and pharmaceutical industries.

Impact of soybean protein isolate concentration on chitosan-cellulose nanofiber edible films: Focus on structure and properties

Chitosan and cellulose nanofiber films are frequently employed as biodegradable materials for food packaging. However, many exhibit suboptimal hydrophobicity and antioxidant properties. To address these shortcomings, we enhanced the performance by adding different concentrations of soybean protein isolate (SPI) to chitosan-cellulose nanofiber (CS-CNF) films. As SPI concentration varied, the turbidity, particle size, and ζ-potential of the film-forming solutions initially decreased and subsequently increased. This suggests that 1 % SPI augments the electrostatic attraction and compatibility. Rheological analysis confirmed a pronounced apparent viscosity at this concentration. Analyses using Fourier transform infrared spectra, Raman spectra, X-ray diffraction, and Scanning electron microscope revealed the presence of hydrogen bonds and electrostatic interactions between SPI and CS-CNF, indicative of superior compatibility. When SPI concentration was set at 1 %, notable enhancements in film attributes were observed: improvements in tensile strength and elongation at break, a reduction in water vapor permeability by 8.23 %, and an elevation in the contact angle by 18.85 %. Furthermore, at this concentration, the ABTS+ and DPPH scavenging capacities of the film surged by 61.53 % and 46.18 %, respectively. Meanwhile, the films we prepare are not toxic. This research offers valuable insights for the advancement and application of protein-polysaccharide-based films.

Recent advances in chitosan-based materials; The synthesis, modifications and biomedical applications

The attention to polymer-based biomaterials, for instance, chitosan and its derivatives, as well as the techniques for using them in numerous scientific domains, is continuously rising. Chitosan is a decomposable naturally occurring polymeric material that is mostly obtained from seafood waste. Because of its special ecofriendly, biocompatible, non- toxic nature as well as antimicrobial properties, chitosan-based materials have received a lot of interest in the field of biomedical applications. The reactivity of chitosan is mainly because of the amino and hydroxyl groups in its composition, which makes it further fascinating for various uses, including biosensing, textile finishing, antimicrobial wound dressing, tissue engineering, bioimaging, gene, DNA and drug delivery and as a coating material for medical implants. This study is an overview of the different types of chitosan-based materials which now a days have been fabricated by applying different techniques and modifications that include etherification, esterification, crosslinking, graft copolymerization and o-acetylation etc. for hydroxyl groups' processes and acetylation, quaternization, Schiff's base reaction, and grafting for amino groups' reactions. Furthermore, this overview summarizes the literature from recent years related to the important applications of chitosan-based materials (i.e., thin films, nanocomposites or nanoparticles, sponges and hydrogels) in different biomedical applications.

Sustainable functionalized chitosan based nano-composites for wound dressings applications: A review

Functionalized chitosan nanocomposites have been studied for wound dressing applications due to their excellent antibacterial and anti-fungal properties. Polysaccharides show excellent antibacterial and drug-release properties and can be utilized for wound healing. In this article, we comprise distinct approaches for chitosan functionalization, such as photosensitizers, dendrimers, graft copolymerization, quaternization, acylation, carboxyalkylation, phosphorylation, sulfation, and thiolation. The current review article has also discussed brief insights on chitosan nanoparticle processing for biomedical applications, including wound dressings. The chitosan nanoparticle preparation technologies have been discussed, focusing on wound dressings owing to their targeted and controlled drug release behavior. The future directions of chitosan research include; a) finding an effective solution for chronic wounds, which are unable to heal completely; b) providing effective wound healing solutions for diabetic wounds and venous leg ulcers; c) to better understanding the wound healing mechanism with such materials which can help provide the optimum solution for wound dressing; d) to provide an improved treatment option for wound healing.

Polymeric Membranes of Chitosan/Aloe Vera Gel Fabrication With Enhanced Swelling and Antimicrobial Properties for Biomedical Applications

Since ancient times, medicinal plants have been used as traditional medicine to treat a variety of ailments. Aloe vera (AV) gel's therapeutic potential is one of the most effective approach in the fabrication of functional materials. The current study aimed to prepare the AV and chitosan (CS) membranes using various cross-linkers that were characterized using X-ray diffraction (XRD), scanning electron microscopy (SEM), Fourier transform-infrared (FT-IR) spectroscopy, thermal gravimetric analysis (TGA), and ultraviolet-visible (UV-Visible) techniques, as well as swelling ratio and antimicrobial studies. SEM analysis revealed that the membrane is porous, with interconnected pores. The inclusion of AV contents in the membrane improved thermal stability and crystallinity. The swelling ratio of the ACPG-3 membrane with a 2:1 CS to AV ratio was 366%. The membranes showed promising antimicrobial activity against Escherichia coli, Staphylococcus aureus, Bacillus subtilis, and Pasteurella multocida strains. The findings revealed that polymeric CS/AV membranes have effective potential for use in the biomedical field.

Electrospun nanofiber based on Ethyl cellulose/Soy protein isolated integrated with bitter orange peel extract for antimicrobial and antioxidant active food packaging

The present work was aimed to produce a novel bioactive nanofiber (NFs) based on Ethyl cellulose (EC), Soy protein isolated (SPI), and containing Bitter orange peel extract (BOPE) by electrospinning technology. The EC/SPI NFs were formulated with different weight ratios of 1:1, 2:1, and 1:2 denoted as ES11, ES21, and ES12, respectively, and investigated by several analyses. Based on the obtained results, the maximum hydrogen interactions between these two polymers, ES11 NFs offered a uniform morphology without bead with the diameter of 185.33 nm as a result of the compatibility of the polymer solutions of EC and SPI. Moreover, appropriate thermal stability was presented along with more porosity (78%), maximum water vapor transmission rate (657 g/m2.24h), good tensile stress (6.12 MPa), and acceptable water contact angel (82.3°). Therefore, ES11 NFs were selected as the optimal sample for incorporation of the BOPE as the antibacterial and antioxidant agent. According to the antioxidant activity test, the highest concentration (20% wt) of this extract increased the antioxidant activity of NF around 64.7% and also inhibited the growth of pathogenic bacteria (S. areus, and E. coli). Therefore, the ES11 electrospun NFs containing 20% BOPE can be a beneficial system to increase the safety and quality of foods.

Strategies to Improve the Properties of Amaranth Protein Isolate-Based Thin Films for Food Packaging Applications: Nano-Layering through Spin-Coating and Incorporation of Cellulose Nanocrystals

In this work, two different strategies for the development of amaranth protein isolate (API)-based films were evaluated. In the first strategy, ultrathin films were produced through spin-coating nanolayering, and the effects of protein concentration in the spin coating solution, rotational speed, and number of layers deposited on the properties of the films were evaluated. In the second strategy, cellulose nanocrystals (CNCs) were incorporated through a casting methodology. The morphology, optical properties, and moisture affinity of the films (water contact angle, solubility, water content) were characterized. Both strategies resulted in homogeneous films with good optical properties, decreased hydrophilic character (as deduced from the contact angle measurements and solubility), and improved mechanical properties when compared with the neat API-films. However, both the processing method and film thickness influenced the final properties of the films, being the ones processed through spin coating more transparent, less hydrophilic, and less water-soluble. Incorporation of CNCs above 10% increased hydrophobicity, decreasing the water solubility of the API films and significantly enhancing material toughness.

Application of a polyelectrolyte complex based on biocompatible polysaccharides for colorectal cancer inhibition

Strategies for incorporating water-insoluble photosensitisers (PS) in drug delivery systems have been extensively studied. In this work, we evaluate the formation, characterisation, drug sorption studies, and cytotoxicity of chitosan (CHT)/chondroitin sulphate (CS) polyelectrolyte complexes (PECs) coated with polystyrene-block-poly(acrylic acid) (PS-b-PAA) nanoparticles (NPs) loaded with chloroaluminum phthalocyanine (AlClPc). The PECs were characterised by infrared spectroscopy (FTIR), differential scanning calorimetric (DSC), X-ray diffraction (XRD), and scanning electron microscopy (SEM). The PS-b-PAA NPs on the PEC surface was confirmed by scanning electron microscopy (SEM). Additionally, optical images distinguished the PEC structures containing PS-b-PAA or PS-b-PAA/AlClPc from the unloaded PEC. Kinetic and equilibrium studies investigate the sorption capacity of the PEC/PS-b-PAA toward AlClPc. The encapsulation efficiency reached 95% at 190 μg mL^-1 AlClPc after only 15 min. The Brunauer-Emmett-Teller (BET) isotherm and pseudo-second-order kinetic fitted well to the experimental data. The PS-b-PAA NPs on the PEC surfaces increase the AlClPc bioavailability and the PEC structure stabilizes the PS-b-PAA/AlClPc nanostructures. The materials were cytocompatible upon healthy VERO (kidney epithelial cells), and cytotoxic against colorectal cancerous cells (HT-29 cells). For the first time, we associate PS-b-PAA/AlClPc with a hydrophilic and cytocompatible polysaccharide matrix. We suggest the use of these materials in strategies to treat cancer by using photodynamic therapy.

Structural evaluation of polymeric microbial films grown on kefir loaded with Maytenus rigida extract

Kefir is a probiotic that has several health promising properties. Its grains can form microbial films on different types of substrates. In the present work, the surface characteristics of kefir biofilms associated with Maytenus rigida Mart. extract were minutely studied. Three different concentrations of plant extract were included in the biofilm forming solutions, where fresh grains of kefir were inoculated. The results showed that the plant extract was successfully incorporated into the exopolysaccharide matrix of the biofilm. The main chemical components found linked to the plant extract were triterpenes. The crystallinity of biofilms increased with the addition of the plant extract. The morphology revealed that at low concentrations of the extract there was a prevalence of lactobacilli, while at high concentrations yeasts were more observed. Adhesion and wettability were higher for biofilm with less extract. These results revealed that a combination of plant extract and kefir's exopolysaccharide could form biofilms with chemical and topographic properties of great interest in regenerative medicine.

N-Acetyl-l-cysteine/l-Cysteine-Functionalized Chitosan-β-Lactoglobulin Self-Assembly Nanoparticles: A Promising Way for Oral Delivery of Hydrophilic and Hydrophobic Bioactive Compounds

Self-assembled and cross-linked hybrid hydrogels for entrapment and delivery of hydrophilic and hydrophobic bioactive compounds were developed based on N-acetyl-l-cysteine (NAC)- or l-cysteine (CYS)-functionalized chitosan-β-lactoglobulin nanoparticles (NPs). In both the systems, amphiphilic protein β-lactoglobulin (β-lg) was self-assembled by using glutaraldehyde for affinity binding with egg white-derived peptides (EWDP) and curcumin and then coated with NAC- or CYS-functionalized chitosan (CS) by electrostatic interaction. The resulting NPs were characterized in terms of size, polydispersity, and surface charge by dynamic light scattering. Results corroborated pH-sensitive properties of NAC-CS-β-lg NPs and CYS-CS-β-lg NPs with the particle size as small as 118 and 48 nm, respectively. The two kinds of NPs also showed excellent entrapment of EWDP and curcumin with the entrapment efficiency (EE) of EWDP and curcumin ranging from 51 to 89% and 42 to 57% in NAC-CS-β-lg NPs, as well as 50-81% and 41-57% in CYS-CS-β-lg NPs under different pH values. Fourier transform infrared and molecular docking studies provided support for the interaction mechanism of NAC/CYS-CS with β-lg as well as the NPs with EWDP and curcumin. Strikingly, the in vitro release kinetics of EWDP and curcumin exhibited the controlled and sustained release properties up to 58 and 70 h from the NPs, respectively. Note that the permeability of QIGLF (pentapeptide, isolated from EWDP) and curcumin passing through Caco-2 cell monolayers were all improved after the entrapment in the NPs. This work offers promising methods for effective entrapment and oral delivery of both hydrophilic and hydrophobic bioactive compounds.

Protein-Based Fiber Materials in Medicine: A Review

Fibrous materials have garnered much interest in the field of biomedical engineering due to their high surface-area-to-volume ratio, porosity, and tunability. Specifically, in the field of tissue engineering, fiber meshes have been used to create biomimetic nanostructures that allow for cell attachment, migration, and proliferation, to promote tissue regeneration and wound healing, as well as controllable drug delivery. In addition to the properties of conventional, synthetic polymer fibers, fibers made from natural polymers, such as proteins, can exhibit enhanced biocompatibility, bioactivity, and biodegradability. Of these proteins, keratin, collagen, silk, elastin, zein, and soy are some the most common used in fiber fabrication. The specific capabilities of these materials have been shown to vary based on their physical properties, as well as their fabrication method. To date, such fabrication methods include electrospinning, wet/dry jet spinning, dry spinning, centrifugal spinning, solution blowing, self-assembly, phase separation, and drawing. This review serves to provide a basic knowledge of these commonly utilized proteins and methods, as well as the fabricated fibers’ applications in biomedical research.

Complex Coacervation of Soy Proteins, Isoflavones and Chitosan

In this study, the chitosan-induced coacervation of soy protein-isoflavone complexes in soymilk was investigated. Most of the soymilk proteins, including β-conglycinin (7S), glycinin (11S), and isoflavones, were found to coacervate into the soymilk pellet fraction (SPF) following the addition of 0.5% chitosan. The total protein in the soymilk supernatant fraction (SSF) decreased from 18.1 ± 0.3 mg/mL to 1.6 ± 0.1 mg/mL, and the pH values decreased slightly, from 6.6 ± 0.0 to 6.0 ± 0.0. The results of SDS-PAGE revealed that the 7S α’, 7S α, 7S β, 11S A3, and 11S acidic subunits, as well as the 11S basic proteins in the SSF, decreased to 0.7 ± 0.5%, 0.2 ± 0.1%, 0.1 ± 0.0%, 0.2 ± 0.2%, 0.2 ± 0.2% and 0.3 ± 0.2%, respectively. We also found that isoflavones in the SSF, including daidzein, glycitein, and genistein, decreased to 9.6 ± 2.3%, 5.7 ± 0.9% and 5.9 ± 1.5%, respectively. HPLC analysis indicated that isoflavones mixed with soy proteins formed soy protein-isoflavone complexes and were precipitated into the SPF by 0.5% chitosan.

Biomedical applications of soy protein: A brief overview

Soy protein (SP) based materials are gaining increasing interest for biomedical applications because of their tailorable biodegradability, abundance, being relatively inexpensive, exhibiting low immunogenicity, and for being structurally similar to components of the extracellular matrix (ECM) of tissues. Analysis of the available literature indicates that soy protein can be fabricated into different shapes, being relatively easy to be processed by solvent or melt based techniques. Furthermore soy protein can be blended with other synthetic and natural polymers and with inorganic materials to improve the mechanical properties and the bioactive behavior for several demands. This review discusses succinctly the biomedical applications of SP based materials focusing on processing methods, properties and applications highlighting future avenues for research.

Synthesis and characterization of a new soy protein isolate/Polyamic acid salt blend films

In this study, a new method was developed to produce biodegradable material using soy protein isolate (SPI) as matrix. The blend films were successfully prepared by casting the aqueous dispersions of SPI and polyamic acid salt (PAS) solution. The effects of blending and PAS content on the structure of the resultant films were investigated by Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), differential scanning calorimetry (DSC) analyses, scanning electron microscopy (SEM). Furthermore, film thickness, water vapor permeability (WVP), water barrier and mechanical properties were measured. The result showed that there exists strong intermolecular interactions between SPI and PAS, which played an important role in forming a homogeneous structure of the blend films. Moreover, the incorporation of PAS enhanced the water barrier and mechanical properties of the films. This is a simple way to prepare biodegradable films compared with other methods and the blend films have the potentiality to be used as food packaging and biomedical materials instead of synthetic polymer.

The influence of UV-irradiation on thermal and mechanical properties of chitosan and silk fibroin mixtures

In the present paper the results regarding the influence of UV-irradiation with 254 nm wavelength on the thermal and mechanical properties and the intrinsic viscosity of chitosan/silk fibroin mixtures are presented. The mixture of chitosan and silk fibroin in solution and thin films made of chitosan/silk fibroin mixture obtained by solvent evaporation were submitted to the treatment with UV irradiation (wavelength 254 nm) for different time intervals. Mechanical properties of thin films made of chitosan/silk fibroin blends before and after UV-irradiation have been investigated by mechanical testing machine and compared with mechanical properties of chitosan films. The changes in such mechanical properties as ultimate breaking strength, percentage of elongation at break and Young Modulus have been investigated. The results have shown, that the mechanical properties of the blends were greatly affected by time of exposure to UV irradiation. Ultimate tensile strength and ultimate percentage of elongation decreased after UV irradiation of the blend. Increasing UV irradiation led to the decrease in Young's Modulus of the chitosan/silk fibroin blend. Viscosity of chitosan/silk fibroin mixtures decreased after UV-irradiation. Thermal properties of the mixtures have been only slightly altered by UV-irradiation.

Hybrid biodegradable membranes of silane-treated chitosan/soy protein for biomedical applications

In recent years, progress in the field of hybrid materials has been accelerated through use of the sol–gel process for creating materials and devices, which benefit from the incorporation of both inorganic and organic components. In this work, organic–inorganic hybrid membranes were prepared from tetraethoxysilane and a blend system composed of chitosan and soy protein. By introducing a small amount of siloxane bond into the chitosan/soy protein system, the chitosan/soy protein hybrid membranes were improved in terms of structure, topography and mechanical properties. It appears that the chitosan/soy protein hybrid membranes were formed by discrete inorganic moieties entrapped in the chitosan/soy protein blend, which improved the stability and mechanical performance assessed by the dynamic mechanical analysis as compared to chitosan/soy protein membrane. Also, in vitro cell culture studies evidenced that the chitosan/soy protein hybrid membranes are non-cytotoxic over a mouse fibroblast-like cell line. The hybrid membranes of silane-treated chitosan/soy protein developed in this work have potential in biomedical applications, including tissue engineering.

An investigation of the potential application of chitosan/aloe-based membranes for regenerative medicine

A significant number of therapeutics derived from natural polymers and plants have been developed to replace or to be used in conjunction with existing dressing products. The use of the therapeutic properties of aloe vera could be very useful in the creation of active wound dressing materials. The present work was undertaken to examine issues concerning structural features, topography, enzymatic degradation behavior, antibacterial activity and cellular response of chitosan/aloe vera-based membranes. The chitosan/aloe vera-based membranes that were developed displayed satisfactory degradation, roughness, wettability and mechanical properties. A higher antibacterial potency was displayed by the blended membranes. Moreover, in vitro assays demonstrated that these blended membranes have good cell compatibility with primary human dermal fibroblasts. The chitosan/aloe vera-based membranes might be promising wound dressing materials.