A Review on Chitosan Utilization in Membrane Synthesis

Research progress on chitin/chitosan-based emulsion delivery systems and their application in lipid digestion regulation

Excessive lipid intake is linked to an elevated risk of health problems. However, reducing lipid contents may influence food structure and flavor. Some alternatives are needed to control the lipid absorption. Emulsions are common carriers for lipids, which can control the hydrolysis and absorption of lipids. Chitin (Ch) and chitosan (CS) are natural polysaccharides with good biodegradability, biocompatibility, and unique cationic properties. They have been reported to be able to delay lipolysis, which can be regarded as one of the most promising agents that regulates lipid digestion (LiD). The application of Ch/CS and their derivatives in emulsions are summarized in this review with a focus on their performances and mechanisms for LiD regulation, aiming to provide theoretical guidance for the development of novel Ch/CS emulsions, and the regulation of LiD. A reasonable design of emulsion interface can provide its resistance to the external environment and then control LiD. The properties of emulsion interface are the key factors affecting LiD. Therefore, systematic study on the relationship between Ch/CS-based emulsion structure and LiD can not only instruct the reasonable design of emulsion interface to accurately regulate LiD, but also provide scientific guidelines for applying Ch/CS in functional food, medicine and other fields.

Recent advance in biomass membranes: Fabrication, functional regulation, and antimicrobial applications

Both inorganic and polymeric membranes have been widely applied for antimicrobial applications. However, these membranes exhibit low biocompatibility, weak biodegradability, and potential toxicity to human being and environment. Biomass materials serve as excellent candidates for fabricating functional membranes to address these problems due to their unique physical, chemical, and biological properties. Here we present recent progress in the fabrication, functional regulation, and antimicrobial applications of various biomass-based membranes. We first introduce the types of biomass membranes and their fabrication methods, including the phase inversion, vacuum filtration, electrospinning, layer-by-layer self-assembly, and coating. Then, the strategies on functional regulation of biomass membranes by adding 0D, 1D, and 2D nanomaterials are presented and analyzed. In addition, antibacterial, antifungal, and antiviral applications of biomass-based functional membranes are summarized. Finally, potential development aspects of biomass membranes are discussed and prospected. This comprehensive review is valuable for guiding the design, synthesis, structural/functional tailoring, and sustainable utilization of biomass membranes.

Synthesis, Characterization and Investigation of Cross-Linked Chitosan/(MnFe2O4) Nanocomposite Adsorption Potential to Extract U(VI) and Th(IV)

A cross-linked chitosan/(MnFe2O4) CCsMFO nanocomposite was prepared using co-precipitation methods and used as a nanomaterial to extract U(VI) and Th(IV) from an aqueous solution based on adsorption phenomena. The contact time of experiments shows a rapid extraction process within 30 min by the CCsMFO nanocomposite. The solution pH acts a critical role in determining qm value, where pH 3.0 was the best pH value to extract both ions. The pseudo-second-order equilibrium model illustrated the kinetics equilibrium modal extraction process. Adsorption isotherm of U(VI) at pH 3.0 by CCsMFO nanocomposite is an endothermic process. In contrast, the adsorption isotherm of Th(IV) at pH 3.0 by CCsMFO nanocomposite is an exothermic process. The reusability of CCsMFO nanocomposite was tested using basic eluents as suitable conditions for the chemical stability of CCsMFO nanocomposite; the reusability results show promising results for the removal of U(VI) adsorbed onto CCsMFO nanocomposite with 77.27%, after 12 h by Na2CO3 as eluent. At the same time, the reusability results show good reusability for removal of U(VI) adsorbed onto CCsMFO nanocomposite with 21.82%, after 8 h by EDTA as eluent.

Expression, characterization, and application potentiality evaluation of recombinant human-like collagen in Pichia pastoris

Collagen is a biofunctional protein that has been widely used in many fields, including but not limited to biomedical, cosmetics and skin care, food, and novel materials. Recombinant collagen has great potential as an alternative to collagen extracted from animals because it avoids the immune response, and the yield and properties are stable. However, challenges remain in the industrial application of recombinant collagen, including improving the expression yield, reducing the cost of purification for industry and expanding applications. In this study, a cloning and recombination method was used to heterologously express the recombinant human-like collagen (RHLC) in Pichia pastoris GS115 using the pPIC9k expression vector. The RHLC expression titre was 2.33 g/L via a 5-L fermenter, and the purification was completed within 48 h and was 98% pure. The characteristics of RHLC were investigated. Furthermore, potential applications for RHLC were explored, such as basal collagen sponge preparation, forming films with chitosan and production of collagen hydrolysed peptides. RHLC has various potential applications due to its triple helical structure, thermostability, good biocompatibility and film-forming ability.

Non-Supported and PET-Supported Chitosan Membranes for Pervaporation: Production, Characterization, and Performance

The objective of this study was to develop non-supported and PET-supported chitosan membranes that were cross-linked with glutaraldehyde, then evaluate their physical-chemical, morphological, and mechanical properties, and evaluate their performance in the separation of ethanol/water and limonene/linalool synthetic mixtures by hydrophilic and target-organophilic pervaporation, respectively. The presence of a PET layer did not affect most of the physical-chemical parameters of the membranes, but the mechanical properties were enhanced, especially the Young modulus (76 MPa to 398 MPa), tensile strength (16 MPa to 27 MPa), and elongation at break (7% to 26%), rendering the supported membrane more resistant. Regarding the pervaporation tests, no permeate was obtained in target-organophilic pervaporation tests, regardless of membrane type. The support layer influenced the hydrophilic pervaporation parameters of the supported membrane, especially in reducing transmembrane flux (0.397 kg∙m^-2∙h^-1 to 0.121 kg∙m^-2∙h^-1) and increasing membrane selectivity (611 to 1974). However, the pervaporation separation index has not differed between membranes (228 for the non-supported and 218 for the PET-supported membrane), indicating that, overall, both membranes had a similar performance. Thus, the applicability of each membrane is linked to specific applications that require a more resistant membrane, greater transmembrane fluxes, and higher selectivity.

A Review of Recent Developments of Pervaporation Membranes for Ethylene Glycol Purification

Ethylene glycol (EG) is an essential reagent in the chemical industry including polyester and antifreeze manufacture. In view of the constantly expanding field of EG applications, the search for and implementation of novel economical and environmentally friendly technologies for the separation of organic and aqueous–organic solutions remain an issue. Pervaporation is currently known to significantly reduce the energy and resource consumption of a manufacturer when obtaining high-purity components using automatic, easily scalable, and compact equipment. This review provides an overview of the current research and advances in the pervaporation of EG-containing mixtures (water/EG and methanol/EG), as well as a detailed analysis of the relationship of pervaporation performance with the membrane structure and properties of membrane materials. It is discussed that a controlled change in the structure and transport properties of a membrane is possible using modification methods such as treatment with organic solvents, introduction of nonvolatile additives, polymer blending, crosslinking, and heat treatment. The use of various modifiers is also described, and a particularly positive effect of membrane modification on the separation selectivity is highlighted. Among various polymers, hydrophilic PVA-based membranes stand out for optimal transport properties that they offer for EG dehydrating. Fabricating of TFC membranes with a microporous support layer appears to be a viable approach to the development of productivity without selectivity loss. Special attention is given to the recovery of methanol from EG, including extensive studies of the separation performance of polymer membranes. Membranes based on a CS/PVP blend with inorganic modifiers are specifically promising for methanol removal. With regard to polymer wettability properties, it is worth mentioning that membranes based on hydrophobic polymers (e.g., SPEEK, PBI/PEI, PEC, PPO) are capable of exhibiting much higher selectivity due to diffusion limitations.

Preparation and Characterization of a Novel Sulfonated Titanium Oxide Incorporated Chitosan Nanocomposite Membranes for Fuel Cell Application

In this study, nano-TiO₂ sulfonated with 1,3-propane sultone (STiO₂) was incorporated into the chitosan (CS) matrix for the preparation of CS/STiO₂ nanocomposite membranes for fuel cell applications. The grafting of sulfonic acid (–SO₃H) groups was confirmed by Fourier transform infrared spectroscopy, thermogravimetric analysis and energy-dispersive X-ray spectroscopy. The physicochemical properties of these prepared membranes, such as water uptake, swelling ratio, thermal and mechanical stability, ion exchange capacity and proton conductivity, were determined. The proton conducting groups on the surface of nano-TiO₂ can form continuous proton conducting pathways along the CS/STiO₂ interface and thus improve the proton conductivity of CS/STiO₂ nanocomposite membranes. The CS/STiO₂ nanocomposite membrane with 5 wt% of sulfonated TiO₂ showed a proton conductivity (0.035 S·cm⁻¹) equal to that of commercial Nafion 117 membrane (0.033 S·cm⁻¹). The thermal and mechanical stability of the nanocomposite membranes were improved because the interfacial interaction between the -SO₃H group of TiO₂ and the –NH₂ group of CS can restrict the mobility of CS chains to enhance the thermal and mechanical stability of the nanocomposite membranes. These CS/STiO₂ nanocomposite membranes have promising applications in proton exchange membrane fuel cells.

Polymers and Solvents Used in Membrane Fabrication: A Review Focusing on Sustainable Membrane Development

(1) Different methods have been applied to fabricate polymeric membranes with non-solvent induced phase separation (NIPS) being one of the mostly widely used. In NIPS, a solvent or solvent blend is required to dissolve a polymer or polymer blend. N-methyl-2-pyrrolidone (NMP), dimethylacetamide (DMAc), dimethylformamide (DMF) and other petroleum-derived solvents are commonly used to dissolve some petroleum-based polymers. However, these components may have negative impacts on the environment and human health. Therefore, using greener and less toxic components is of great interest for increasing membrane fabrication sustainability. The chemical structure of membranes is not affected by the use of different solvents, polymers, or by the differences in fabrication scale. On the other hand, membrane pore structures and surface roughness can change due to differences in diffusion rates associated with different solvents/co-solvents diffusing into the non-solvent and with differences in evaporation time. (2) Therefore, in this review, solvents and polymers involved in the manufacturing process of membranes are proposed to be replaced by greener/less toxic alternatives. The methods and feasibility of scaling up green polymeric membrane manufacturing are also examined.

Flow-assembled chitosan membranes in microfluidics: recent advances and applications

The integration of membranes in microfluidic devices has been extensively exploited for various chemical engineering and bioengineering applications over the past few decades. To augment the applicability of membrane-integrated microfluidic platforms for biomedical and tissue engineering studies, a biologically friendly fabrication process with naturally occurring materials is highly desired. The in situ preparation of membranes involving interfacial reactions between parallel laminar flows in microfluidic networks, known as the flow-assembly technique, is one of the most biocompatible approaches. Membranes of many types with flexible geometries have been successfully assembled inside complex microchannels using this facile and versatile flow-assembly approach. Chitosan is a naturally abundant polysaccharide known for its pronounced biocompatibility, biodegradability, good mechanical stability, ease of modification and processing, and film-forming ability under near-physiological conditions. Chitosan membranes assembled by flows in microfluidics are freestanding, robust, semipermeable, and well-aligned in microstructure, and show high affinity to bioactive reagents and biological components (e.g. biomolecules, nanoparticles, or cells) that provide facile biological functionalization of microdevices. Here, we discuss the recent developments and optimizations in the flow-assembly of chitosan membranes and chitosan-based membranes in microfluidics. Furthermore, we recapitulate the applications of the chitosan membrane-integrated microfluidic platforms dedicated to biology, biochemistry, and drug release fields, and envision the future developments of this important platform with versatile functions.

Restructuring thin film composite membrane interfaces using biopolymer as a sustainable alternative to prevent organic fouling

Replacing polyamide (PA) layer in commercially successful thin film composite (TFC) membranes prepared via interfacial polymerization has been challenging task. Lately, PA is under scrutiny due to its increasing fouling propensity for highly contaminated waters. To mitigate the bio and organic fouling on PA layer in nanofiltration (NF) membranes in a long run, present study attempts to create a new interfacial thin film asymmetric structure using biopolymer chitosan as sustainable alternative. Herein, the effect of chitosan-silver on porous support structure and filtration performance were systematically investigated. Further, the membranes were characterized for their functionality and surface characteristics using ATR-IR, FESEM, AFM, UV-vis spectroscopy and contact angle measurements, respectively. New asymmetric membrane performances in cross flow process were evaluated in terms of pure water flux, NaCl (∼40 %), red brown/organic dye (>98 %) and tannery wastewater flux and rejection (>98 %). With a higher pure water flux (>100 L m^-2 h^-1) compared to control (40 L m^-2 h^-1) at 4 bar, membrane showed exceptional antifouling behaviors in comparison to commercial PA membrane. Further, surface characteristics of the membranes before and after rigorous testing were evaluated using AFM micrographs and SEM imaging.

Preliminary Evaluation of 3D Printed Chitosan/Pectin Constructs for Biomedical Applications

In the present study, chitosan (CS) and pectin (PEC) were utilized for the preparation of 3D printable inks through pneumatic extrusion for biomedical applications. CS is a polysaccharide with beneficial properties; however, its printing behavior is not satisfying, rendering the addition of a thickening agent necessary, i.e., PEC. The influence of PEC in the prepared inks was assessed through rheological measurements, altering the viscosity of the inks to be suitable for 3D printing. 3D printing conditions were optimized and the effect of different drying procedures, along with the presence or absence of a gelating agent on the CS-PEC printed scaffolds were assessed. The mean pore size along with the average filament diameter were measured through SEM micrographs. Interactions among the characteristic groups of the two polymers were evident through FTIR spectra. Swelling and hydrolysis measurements confirmed the influence of gelation and drying procedure on the subsequent behavior of the scaffolds. Ascribed to the beneficial pore size and swelling behavior, fibroblasts were able to survive upon exposure to the ungelated scaffolds.

Dual ionic liquid-based crosslinked chitosan for fine-tuning of antifouling, water throughput, and denitrification performance of polysulfone membrane

This study aimed to design a facile and efficient protocol for upgrading the performance indices of polysulfone (PS) membrane (porosity, hydrophilicity, pure water flux (PWF), surface charge, and fouling-resistance) by blending with newly synthesized poly(ionic) crosslinked chitosan Schiff bases (PICCSBs). The PS-PICCSBs mixed-matrix membranes (MMMs) have successfully fabricated and characterized based on spectral and microscopic analyses, porosity, zeta potential, water contact angle, and water uptake (wettability) measurements. The PWF, fouling-resistance against bovine serum albumin (BSA), as well as ion exchange capacity (IEC) against nitrate anion were studied. The wettability, hydrophilicity and overall porosity of new MMMs have greatly increased, in comparison to a pristine PS membrane (M₀). In addition, blending of PS with PICCSBs resulted in switching its surface from negatively- to positively-charged. The PWF of MMMs has increased to reach a maximum value of 238.6 L/m² h for MMM₁ (9.3-fold higher than M₀). Meanwhile, BSA rejection has declined from 96.62% for M₀ to 41.9% for MMM₁. The fouling parameters results of MMMs indicated their low fouling propensity. The IEC of nitrate anions revealed that the nitrate uptake by MMM₁ is higher than that for M₀ and MMM₂ by 34% and 14%, respectively.

Characterization of a Bioresorbable Magnesium-Reinforced PLA-Integrated GTR/GBR Membrane as Dental Applications

Inferior mechanical properties have always been a limitation of the bioresorbable membranes in GBR/GTR. This study is aimed at fabricating a bioresorbable magnesium-reinforced polylactic acid- (PLA-) integrated membrane and investigating its mechanical properties, degradation rate, and biocompatibility. The uncoated and fluoride-coated magnesium alloys, AZ91, were made into strips. Then, magnesium-reinforced PLA-integrated membrane was made through integration. PLA strips were used in the control group instead of magnesium strips. Specimens were cut into rectangular shape and immersed in Hank's Balanced Salt Solution (HBSS) at 37°C for 4, 8, and 12 d. The weight loss of the AZ91 strips was measured. Three-point bending tests were conducted before and after the immersion to determine the maximum load on specimens. Potentiodynamic polarization (PDP), electrochemical impedance spectroscopy (EIS), scanning electron microscopy (SEM), and energy-dispersive spectroscopy (EDS) were conducted on coated and uncoated AZ91 plates to examine corrosion resistance. Murine fibroblast and osteoblast cells were cultured on circular specimens and titanium disks for 1, 3, and 5 d. Thereafter, WST test was performed to examine cell proliferation. As a result, the coated and uncoated groups showed higher maximum loads than the control group at all time points. The weight loss of AZ91 strips used in the coated group was lower than that in the uncoated group. PDP, EIS, SEM, and EDS showed that the coated AZ91 had a better corrosion resistance than the uncoated AZ91. The cell proliferation test showed that the addition of AZ91 did not have an adverse effect on osteoblast cells. Conclusively, the magnesium-reinforced PLA-integrated membrane has excellent load capacity, corrosion resistance, cell affinity, and proper degradation rate. Moreover, it has great potential as a bioresorbable membrane in the GBR/GTR application.

Alkaline Phosphatase Immobilization on New Chitosan Membranes with Mg2+ for Biomedical Applications

In this paper, we present the fabrication and characterization of new chitosan-based membranes while using a new biotechnology for immobilizing alkaline phosphatase (ALP). This technology involved metal ions incorporation to develop new biopolymeric supports. The chemical structure and morphological characteristics of proposed membranes were evaluated by infrared spectroscopy (FT-IR) and the scanning electron microscopy technique (SEM). The inductively coupled plasma mass spectrometry (ICP-MS) evidenced the metal ion release in time. Moreover, the effect of Mg²⁺ on the enzymatic activity and the antibacterial investigations while using Gram-negative Escherichia coli and Gram-positive Staphylococcus aureus bacteria, hemolysis, and biocompatibility behavior were studied. Immobilizing ALP into the chitosan membranes composition followed by the incorporation of Mg²⁺ led to polymeric supports with enhanced cellular viability when comparing to chitosan-based membranes without Mg²⁺. The results obtained evidenced promising performance in biomedical applications for the new biopolymeric supports that are based on chitosan, ALP, and metal ions.