Development of dual crosslinked mumio-based hydrogel dressing for wound healing application: Physico-chemistry and antimicrobial activity.

In this study, an antimicrobial mumio-based hydrogel dressing was developed for wound healing application. The mechanism of gel formation was achieved via a double crosslink network formation between gelatin (GT) and polyvinyl alcohol (PVA) using polyethylene glycol diglycidyl ether (PEGDE) and borax as crosslinking agents. To enhance the mechanical integrity of the hydrogel matrix, bacterial cellulose (BC) was integrated into the GT-PVA hydrogel to produce a composite gel dressing. The obtained hydrogel was characterized by FTIR, SEM, TGA, and XRD. Gel fraction, in vitro swelling and degradation as well as compressive modulus properties of the gel dressing were investigated as a function of change in PVA and BC ratios. By increasing the ratios of PVA and BC, the composite dressing showed lower swelling but higher mechanical strength. Comparing to other formulations, the gel with 4 %w/v PVA and 1 %w/v BC demonstrated to be most suitable in terms of stability and mechanical properties. In vitro cell cytotoxicity by MTT assay on human alveolar basal epithelial (A549) cell lines validated the gels as non-toxic. In addition, the mumio-based gel was compared to other formulations containing different bioactive agents of beeswax and cinnamon oil, which were tested for microbial growth inhibition effects against different bacteria (S. aureus and K. pneumoniae) and fungi (C. albicans and A. niger) strains. Results suggested that the gel dressing containing combinations of mumio, beeswax and cinnamon oil possess promising future in the inhibition of microbial infection supporting its application as a suitable dressing for wound healing.

Self-crosslinked chitosan/dialdehyde xanthan gum blended hypromellose hydrogel for the controlled delivery of ampicillin, minocycline and rifampicin.

The design of improved biopolymeric based hydrogel materials with high load-capacity to serve as biocompatible drug carriers is a challenging task with vital implications in health sciences. In this work, chitosan crosslinked dialdehyde xanthan gum interpenetrated hydroxypropyl methylcellulose gels were developed for the controlled delivery of different antibiotic drugs including ampicillin, minocycline and rifampicin. The prepared hydrogel scaffolds were characterized by rheology method, FTIR, SEM, TGA and compression analysis. In addition, gelation kinetics, swelling, in vitro degradation and drug release rate were studied under simulated gastrointestinal fluid conditions of pH 2.0 and 7.4 at 37 °C. Results demonstrated the gel composition and structure affected drug release kinetics. The release study showed more than 50% cumulative release within 24 h for all investigated antibiotic drugs. In vitro cell cytocompatibility using mouse embryonic fibroblast cell lines depicted ≥80% cell viability, indicating the gels are non-toxic. Finally, the antibacterial activity of loaded gels was evaluated against Gram-negative and positive bacteria (Escherichia coli, Staphylococcus aureus and Klebsiella pneumonia), which correlated well with swelling and drug release results. Overall, the present study demonstrated that the produced hydrogel scaffolds serves as promising material for controlled antibiotic delivery towards microbial growth inhibition.

Effect of Iron-Oxide Nanoparticles Impregnated Bacterial Cellulose on Overall Properties of Alginate/Casein Hydrogels: Potential Injectable Biomaterial for Wound Healing Applications.

In this study we report the preparation of novel multicomponent hydrogels as potential biomaterials for injectable hydrogels comprised of alginate, casein and bacterial cellulose impregnated with iron nanoparticles (BCF). These hydrogels demonstrated amide cross-linking of alginate-casein, ionic cross-linking of alginate and supramolecular interaction due to incorporation of BCF. Incorporation of BCF into the hydrogels based on natural biopolymers was done to reinforce the hydrogels and impart magnetic properties critical for targeted drug delivery. This study aimed to improve overall properties of alginate/casein hydrogels by varying the BCF loading. The physico-chemical properties of gels were characterized via FTIR, XRD, DSC, TGA, VSM and mechanical compression. In addition, swelling, drug release, antibacterial activity and cytotoxicity studies were also conducted on these hydrogels. The results indicated that incorporation of BCF in alginate/casein hydrogels led to mechanically stronger gels with magnetic properties, increased porosity and hence increased swelling. A porous structure, which is essential for migration of cells and biomolecule transportation, was confirmed from microscopic analysis. The porous internal structure promoted cell viability, which was confirmed through MTT assay of fibroblasts. Moreover, a hydrogel can be useful for the delivery of essential drugs or biomolecules in a sustained manner for longer durations. These hydrogels are porous, cell viable and possess mechanical properties that match closely to the native tissue. Collectively, these hybrid alginate-casein hydrogels laden with BCF can be fabricated by a facile approach for potential wound healing applications.

Silk nano-discs: A natural material for cancer therapy.

The article demonstrates the crystalline silk nano-discs (CSNs), with well-controlled morphology, which upon magnetization, yields magnetic crystalline silk nano-discs, making both prominent alternatives for replacing metal templates such as gold, silver, and so on in therapeutics and implants. The isolated ß-sheet-rich discotic CSNs have ~50 nm diameter, high crystallinity (> 90%), and are insoluble but provide good dispersibility and stability in aqueous solutions. The melt blending-cum-electrospinning of functionalized CSN with poly(lactic acid) results in biocompatible nanofiber-based scaffolds having in vitro cell cytocompatibility with improved cell adhesion and proliferation. The assessment of release behavior of curcumin, a naturally occurring anticancer drug, shows sustained release over 25 days exhibiting effective cytotoxicity against human cervical cancer cells. Further, combined effect of curcumin and hyperthermia reduced the cell growth by ~63%. Alignment of CSN-derived magnetic nanoparticles due to effective fiber drawing process during electrospinning could improve cytocompatibility against BHK-21 cells, and therefore efficacy for cancer therapy.

Recycling of poly (lactic acid)/silk based bionanocomposites films and its influence on thermal stability, crystallization kinetics, solution and melt rheology.

In this study, the effect of silk nanocrystals (SNCs) on the thermal and rheological properties of poly (lactic acid) (PLA) under repetitive extrusion process is investigated. The presence of SNCs facilitates the crystallization process and delaying the thermal degradation of PLA matrix. This leads to the reduction in cold crystallization peak temperature with lower crystallization half-time and higher growth rate. The substantial improvement in nucleation density observed through Polarized Optical Microscope (POM) proves the nucleating effect of SNC in all processing cycles. Moreover, the rheological investigation (complex viscosity, storage and loss modules values) revealed the stabilizing effect of SNC and the drastic degradation of neat PLA (NPLA) in third and fourth cycle is observed to be fortified by the presence of SNC. Cole-Cole plot and cross over frequencies have been correlated with the molar mass distribution of PLA and PLA-Silk composite during processing, which is further supported by the intrinsic viscosity measurement and acid value analysis. This investigation suggests that the melt viscosity and thermal properties of PLA can be stabilized by addition of silk nanocrystals.

Nanosilk-Grafted Poly(lactic acid) Films: Influence of Cross-Linking on Rheology and Thermal Stability.

This article reports a novel fabrication of branched cum cross-linked poly(lactic acid) (PLA) with nanosilk fibroin with graft chain topology by reactive extrusion process. It could be possible by the addition of a small amount of radical initiator (dicumyl peroxide (DCP)). Grafting of silk nanocrystals (SNCs) on PLA macromolecules that provides remarkable improvement in the rheological and thermal properties of the latter are confirmed by 1H NMR and Fourier transform infrared investigation. Significant improvement is observed in zero shear viscosities, and the crossover point shifts to lower frequencies as compared to the branched and cross-linked PLA system. Along with SNC grafting, the crystallization process is also enhanced and stable crystals appeared during cooling, which results in a single melting peak. The rate of crystallization of PLA has been improved although the percentage crystallinity reduces with DCP content, as higher grafting and cross-linking restricts the chain segmental motion, which is critical for crystallization process. Furthermore, SNC grafting increases the reprocessability performance of PLA and provides higher rheological properties as compared to the branched and cross-linked PLA at all reprocessing cycles.