Acidic ionic liquid catalyzed crosslinking of oxycellulose with chitosan for advanced biocomposites

Injectable multifunctional carboxymethyl chitosan/hyaluronic acid hydrogel for drug delivery systems

Injectable hydrogels with notable mechanical properties and self-healing ability are promising carriers for use as a drug delivery system. Here, adipic acid dihydrazide (ADH) and calcium ions (Ca2+) were introduced into quaternary ammonium carboxymethyl chitosan and aldehyde-modified hyaluronic acid hydrogels (QCS + OHA). The hydrogels were synthesized through the interaction of the Schiff bases (imine bonds, acylhydrazone bonds) and coordination bonds via a facile one-step approach. The gelation time (∼54 s) ensured excellent injectability. The QCS + OHA + ADH + Ca2+ hydrogel had notable mechanical properties (compressive stress up to 896.30 KPa), good self-healing ability (up to 94 %), good pH responsiveness, and excellent antibacterial properties. In addition, the QCS + OHA + ADH + Ca2+ hydrogel had a high drug loading capacity (121.3 mg/g) and sustained drug release behaviour (≥120 h). The results of cytotoxicity tests showed a high cell proliferation rate (up to 98 %) and good cytocompatibility. In summary, this work presents an injectable and self-healing pH-responsive hydrogel that can be used as a carrier for drug delivery systems.

Green Chemistry Principles for Nano- and Micro-Sized Hydrogel Synthesis

The growing demand for drug carriers and green-technology-based tissue engineering materials has enabled the fabrication of different types of micro- and nano-assemblies. Hydrogels are a type of material that have been extensively investigated in recent decades. Their physical and chemical properties, such as hydrophilicity, resemblance to living systems, swelling ability and modifiability, make them suitable to be exploited for many pharmaceutical and bioengineering applications. This review deals with a brief account of green-manufactured hydrogels, their characteristics, preparations, importance in the field of green biomedical technology and their future perspectives. Only hydrogels based on biopolymers, and primarily on polysaccharides, are considered. Particular attention is given to the processes of extracting such biopolymers from natural sources and the various emerging problems for their processing, such as solubility. Hydrogels are catalogued according to the main biopolymer on which they are based and, for each type, the chemical reactions and the processes that enable their assembly are identified. The economic and environmental sustainability of these processes are commented on. The possibility of large-scale processing in the production of the investigated hydrogels are framed in the context of an economy aimed at waste reduction and resource recycling.

Structure and properties of oxycellulose fabric crosslinked with soy protein

Cotton is an important renewable biopolymer with extensive applications in various fields including textiles. In the current study a soy protein (SP) crosslinked cotton fabric (SPCCF) was prepared through the reaction of carboxyl cotton fabric with soy protein without using crosslinking agents. FTIR analysis of SPCCF samples indicated that carboxyl groups in oxycellulose fabric have reacted with amino groups of SP to give the corresponding C-N bond, that was also reconfirmed by XPS spectra and TGA/DTG analyses of the grafted fabrics. The resulting SPCCF fabrics acquired under the optimized conditions exhibited the improved tensile strength and capillary effect as compared to the oxidized cotton fabric. The ungrafted and grafted fabrics were further evaluated for dyeing property, as a result, the SPCCF fabrics showed markedly improved colour strength when dyed with acid dyes. The fastness properties of dyeability for the dyed SPCCF fabrics were also good compared with that of ungrafted fabrics by dyeing. Shikonin as a kind of Chinese medicine was found to immobilize on the SPCCF fabric through treatment with shikonin aqueous solution, such fabric displayed effective antibacterial activities against both gram-positive and gram-negative bacteria with durability of 30 washes. These results suggest that the SPCCF can be suitable for medical protective textiles by immobilizing drugs.

Interfacial structure and property of eco-friendly carboxymethyl cellulose/poly(3-hydroxybutyrate-co-3-hydroxyvalerate) biocomposites

This paper investigates the interface bonding of the novel carboxymethyl cellulose (CMC)/poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV) biocomposites, and the influence of coupling agents on the structure and properties of the biocomposites. The chemical structure, crystallisation behaviour and microstructure of the untreated and coupling agent treated biocomposites were examined by using FTIR, XRD and SEM respectively. The results suggested that maleic anhydride (MA) and vinyltrimethoxysilane (VTMS) covalently bonded to both CMC and PHBV macromolecules owing to their intrinsic multifunctionality, and promoted the distribution and embedment of the CMC in PHBV matrix, leading to a superior interfacial bonding of the resulted biocomposites. The enhanced interfacial bonding between the CMC and PHBV gave rise to a significant increase of tensile and flexural properties (i.e. tensile and flexural stress increased by up to 71% and 117% respectively, Young's and flexural modulus increased by up to 17% and 18% respectively) as well as thermal stability of the biocomposites.

Chitosan Derivatives: Introducing New Functionalities with a Controlled Molecular Architecture for Innovative Materials

The functionalization of polymeric substances is of great interest for the development of innovative materials for advanced applications. For many decades, the functionalization of chitosan has been a convenient way to improve its properties with the aim of preparing new materials with specialized characteristics. In the present review, we summarize the latest methods for the modification and derivatization of chitin and chitosan under experimental conditions, which allow a control over the macromolecular architecture. This is because an understanding of the interdependence between chemical structure and properties is an important condition for proposing innovative materials. New advances in methods and strategies of functionalization such as the click chemistry approach, grafting onto copolymerization, coupling with cyclodextrins, and reactions in ionic liquids are discussed.