Synthesis of quaternised guar gum using Taguchi L(16) orthogonal array

Self-healing hydrogels based on biological macromolecules in wound healing: A review

The complete healing of skin wounds has been a challenge in clinical treatment. Self-healing hydrogels are special hydrogels formed by distinctive physicochemically reversible bonds, and they are considered promising biomaterials in the biomedical field owing to their inherently good drug-carrying capacity as well as self-healing and repair abilities. Moreover, natural polymeric materials have received considerable attention in skin tissue engineering owing to their low cytotoxicity, low immunogenicity, and excellent biodegradation rates. In this paper, we review recent advances in the design of self-healing hydrogels based on natural polymers for skin-wound healing applications. First, we outline a variety of natural polymers that can be used to construct self-healing hydrogel systems and highlight the advantages and disadvantages of different natural polymers. We then describe the principle of self-healing hydrogels in terms of two different crosslinking mechanisms-physical and chemical-and dissect their performance characteristics based on the practical needs of skin-trauma applications. Next, we outline the biological mechanisms involved in the healing of skin wounds and describe the current application strategies for self-healing hydrogels based on these mechanisms. Finally, we analyze and summarize the challenges and prospects of natural-material-based self-healing hydrogels for skin applications.

New Quaternary Ammonium Derivatives Based on Citrus Pectin

New citrus pectin derivatives carrying pendant N,N-dimethyl-N-alkyl-N-(2-hydroxy propyl) ammonium chloride groups were achieved via polysaccharide derivatization with a mixture of N,N-dimethyl-N-alkyl amine (alkyl = ethyl, butyl, benzyl, octyl, dodecyl) and epichlorohydrin in aqueous solution. The structural characteristics of the polymers were examined via elemental analysis, conductometric titration, Fourier Transform Infrared spectroscopy (FTIR) and 1D (1H and 13C) nuclear magnetic resonance (NMR). Capillary viscosity measurements allowed for the study of viscometric behavior as well as the determination of viscosity-average molar mass for pristine polysaccharide and intrinsic viscosity ([η]) values for pectin and its derivatives. Dynamic light scattering measurements (DLS) showed that pectin-based polymers formed aggregates in aqueous solution with a unimodal distribution. Critical aggregation concentration (cac) for the hydrophobic pectin derivatives were determined using fluorescence spectroscopy. Atom force microscopy (AFM) images allowed for the investigation of the morphology of polymeric populations obtained in aqueous solution, consisting of flocs and aggregates for crude pectin and its hydrophilic derivatives and well-organized aggregates for lipophilic pectin derivatives. Antimicrobial activity, examined using the disc diffusion method, proved that all polymers were active against Staphylococcus aureus bacterium and Candida albicans yeast.

Enzymatically mediated Gleditsia sinensis galactomannan based hydrogel inspired by wound healing process

The self-healing property based on metal-ligand physical coordination is particularly interesting in bio-hydrogel science due to its allowance for multiple local healing events to process. As the most abundant renewable green resource in nature, Gleditsia sinensis galactomannan has great potential as a starting material for functional materials. In this study, the biocompatible Gleditsia sinensis galactomannan and cellulose were firstly chemically modified and then taken as the main constituent for constructing the metal-ligand coordination through an enzyme-regulated strategy. The hydrogel could quickly gelatinize in the surrounding environment, corresponding to the violent exothermic phenomenon, and exhibit extraordinary self-healing behavior. The molecular dynamics simulation of the hydrogel confirmed the more stable coordinated configuration from Fe(III)-chelates than Fe(II)-chelates. The morphology, mechanical property, antibacterial, and cytotoxicity of the prepared hydrogel were also studied. Our results indicated that galactomannan hydrogel based on the metal-ligand networks could balance the kinetic stability and intrinsic healability through the enzyme-induced route, which provide a new perspective in the field of biomaterial applications.

Oral delivery of curcumin via multi-bioresponsive polyvinyl alcohol and guar gum based double-membrane microgels for ulcerative colitis therapy

Anti-inflammatory drugs for ulcerative colitis (UC) treatment should specifically penetrate and accumulate in the colon tissue. Herein, a multi-bioresponsive anti-inflammatory drug (curcumin, CUR)-loaded heterogeneous double-membrane microgels (CUR@microgels) for oral administration was fabricated in this study, in which the inner core was derived from polyvinyl alcohol (PVA) and guar gum (GG) and the outer gel was decoration with alginate and chitosan by polyelectrolyte interactions. The structure and morphology of microgels were characterized. In vitro, the formulation exhibited good bio-responses at different pH conditions and sustained-release properties in simulated colon fluid with a drug-release rate of 84.6 % over 34 h. With the assistance of the outlayer gels, the microgels effectively delayed the premature drug release of CUR in the upper gastrointestinal tract. In vivo studies revealed that CUR@microgels specifically accumulated in the colon tissue for 24 h, which suggest that the interlayer gels were apt to reach colon lesion. As expected, the oral administration of microgels remarkably alleviated the symptoms of UC and protected the colon tissue in DSS-induced UC mice. The above results indicated that these facilely fabricated microgels which exhibited excellent biocompatibility and multi-bioresponsive drug release, had an apparent effect on the treatment of UC, which represents a promising drug delivery strategy for CUR in a clinical application.

A self-healing and injectable oxidized quaternized guar gum/carboxymethyl chitosan hydrogel with efficient hemostatic and antibacterial properties for wound dressing

Multifunctional wound dressings urgently need to be developed to meet the various needs of wound healing. In this work, we first proposed a new method about modifying the guar gum (GG) by performing a quaternization graft reaction and then oxidation. The obtained oxidized quaternized guar gum (OQGG) not only has antibacterial function due to the introduction of quaternary ammonium groups, but also can become one of the components of Schiff base hydrogels due to the presence of aldehyde groups. Therefore, we used it and carboxymethyl chitosan (CMCS) to design a hydrogel with antibacterial, hemostatic, self-repairing and injectable properties. We characterized the structure of OQGG and OQGG@CMCS hydrogels, but also evaluated the performance of the hydrogels. The results showed that GG was successfully modified to OQGG and OQGG@CMCS hydrogel was successfully prepared, and the obtained OQGG@CMCS hydrogel showed excellent antibacterial and hemostatic properties, and exhibited self-healing and injectability. In addition, cytotoxicity tests demonstrated that the OQGG@CMCS hydrogels presented good cytocompatibility. Further, the OQGG@CMCS hydrogel significantly promoted wound healing in an S. aureus-infected rat wound model. Therefore, the hydrogel has the potential to be applied as a wound dressing.

Synthesis, characterization, and selective dye adsorption by pH- and ion-sensitive polyelectrolyte galactomannan-based hydrogels

Three novel polyelectrolyte galactomannan hydrogels (PGHs) were fabricated by chemically crosslinking quaternary ammonium galactomannan (QAG) and carboxymethyl galactomannan (CMG), and employed for the removal of Congo Red (CR) and Methylene Blue (MB). Physicochemical characterization revealed that the PGHs are chemically and physically crosslinked. The PGHs are pH- and ion-sensitive, and their physical crosslinking can be destroyed by artificial urine; water swelling capacity (100.6-321.9 g/g dry gel) and artificial urine swelling capacity (35.9-80.5 g/g dry gel). The adsorption of CR and MB was studied and found to be pH-dependent and selective. The maximum adsorption capacities of CR and MB on the QAG and CMG gels are 1441 and 94.52 mg/g, respectively, and their adsorption kinetics and isotherm behavior obey the pseudo-second-order kinetics model and Langmuir isotherm model, respectively. The adsorption mechanism is dominated by electrostatic interactions and hydrogen bonding. Further, the PGHs have excellent salt resistance and are reusable.

The Experimental Process Design of Artificial Lightweight Aggregates Using an Orthogonal Array Table and Analysis by Machine Learning

The purpose of this study is to experimentally design the drying, calcination, and sintering processes of artificial lightweight aggregates through the orthogonal array, to expand the data using the results, and to model the manufacturing process of lightweight aggregates through machine-learning techniques. The experimental design of the process consisted of L₁₈(3⁶6¹), which means that 3⁶ × 6¹ data can be obtained in 18 experiments using an orthogonal array design. After the experiment, the data were expanded to 486 instances and trained by several machine-learning techniques such as linear regression, random forest, and support vector regression (SVR). We evaluated the predictive performance of machine-learning models by comparing predicted and actual values. As a result, the SVR showed the best performance for predicting measured values. This model also worked well for predictions of untested cases.

Thermal, spectroscopic, SEM and rheological datasets of native and quaternized guar gum

The manuscript reports TGA, DTA, SEM and NMR datasets of native and quaternized guar gum as a tool for their characterization. The TGA and DTA data was acquired in temperature range 35–500 °C. Based on the TGA experimental values, activation energy plots were drawn to study the stability of native and quaternized polysaccharides (Cai and Bi, 2008 [1]). The data demonstrates the thermal behaviour of quaternized guar gum vis-a-vis native guar gum. The surface morphology of native and quaternized galactomannan was represented by SEM imaging. The ¹H–¹H COSY was acquired to understand structural changes by quaternization. The rheological measurements of native and modified products were carried out to obtain the viscosity profile of the respective samples. The datasets support the research article ‘Synthesis of quaternized guar gum using Taguchi L (16) orthogonal array’ (Tyagi et al., 2020 [2]).