Nanotailoring of Nanocomposite Hydrogels Containing POSS

Silver functionalized chitosan composite hydrogel with sustained silver release and enhanced antibacterial properties promotes healing of infected wounds

Bacterial infections during wound healing often cause inflammation, which delays the healing process. Therefore, innovative wound dressings are urgently needed to inhibit bacterial infections and promote healing. This study proposes an Ag-functionalized chitosan hydrogel dressing, formed via a Schiff-base reaction between alkynyl Ag substituted chitosan (Ag-CS) and octafunctionalized polyhedral oligomeric silsesquioxane with benzaldehyde-terminated polyethylene glycol (POSS-PEG-CHO), to address the issue of bacterial infection in wounds. The hydrogel demonstrated excellent injectability and self-healing properties. AgNPs and alkynyl Ag, produced by the reducing effect of chitosan and the reversible reaction of alkynyl Ag, delay the release of Ag+. Furthermore, the hydrogel exhibits a broad-spectrum antibacterial effect and effectively inhibits bacterial biofilm formation. The release of Ag+ lasts for 7 days, ensuring sustainable antibacterial properties. In a mouse infected wound model, the composite hydrogel significantly accelerated wound healing. By the eighth day, the wound healing rate reached 99 %, whereas the control group achieved only 91 %. Histological and immunofluorescence staining results indicated that hydrogel-treated wounds had faster re-epithelialization, collagen deposition, and angiogenesis, with reduced inflammation. In conclusion, the Ag-functionalized chitosan hydrogel, with sustained Ag release and enhanced antibacterial properties, shows great potential as a wound dressing for promoting the healing of infected wounds.

Injectable self-healing chitosan-based POSS-PEG hybrid hydrogel as wound dressing to promote diabetic wound healing

Promoting the healing of diabetic wounds remains a major challenge in scientific research today. A star-like eight-arm cross-linker octafunctionalized POSS of benzaldehyde-terminated polyethylene glycol (POSS-PEG-CHO) was synthesized, and crosslinked with hydroxypropyltrimethyl ammonium chloride chitosan (HACC) via Schiff base reaction to obtain Chitosan-based POSS-PEG hybrid hydrogels. The designed composite hydrogels exhibited strong mechanical strength, injectability, excellent self-healing efficiency, good cytocompatibility and antibacterial properties. Furthermore, the composite hydrogels could accelerate cells migration and proliferation, as expected by remarkably promoting wound healing in diabetic mice. The wounds treated with the composite hydrogels displayed faster regeneration of epithelial tissue, fewer inflammatory cells, more collagen deposition and higher expression level of VEGF. Therefore, Chitosan-based POSS-PEG hybrid hydrogel has great application potential as a dressing for promoting the healing of diabetic wounds.

Novel poss reinforced chitosan composite membranes for guided bone tissue regeneration

In this study, novel composites membranes composed of chitosan matrix and polyhedral oligomeric silsesquioxanes (POSS) were fabricated by solvent casting method. The effect of POSS loading on the mechanical, morphological, chemical, thermal and surface properties, and cytocompatibility of composite membranes were investigated and observed by tensile test, atomic force microscopy (AFM), Fourier transform infrared spectroscopy (FTIR), thermal gravimetric analysis (TGA), protein adsorption assay, air/water contact angle analysis and WST-1 respectively. Swelling studies were also performed by water absorption capacity determination. Results showed that incorporation of Octa-TMA POSS^® nanofiller to the chitosan matrix increased the surface roughness, protein adsorption and swelling capacity of membranes. The addition of POSS enhanced significantly the ultimate tensile strength and strain at break of the composite membranes up to 3 wt% POSS loaded samples. An increase of about 76% in tensile strength and of strain at break 1.28% was achieved for 3 wt% POSS loaded nanocomposite membranes compared with chitosan membranes. The presence of POSS filler into polymer matrix increased the plasma protein adsorption on the surface. Maximum protein capacity and swelling was obtained for 10 wt% loaded samples. High cell viability results were obtained with indirect extraction of chitosan/POSS composites. Besides, cell proliferation and ALP activity results showed that POSS incorporation significantly increased the ALP activity of Saos-2 cells cultured on chitosan membranes. This novel composite membranes with tunable properties could be considered as a potential candidate for guided bone regeneration applications.

Injectable shear-thinning hydrogels with enhanced strength and temperature stability based on polyhedral oligomeric silsesquioxane end-group aggregation

A strategy based on the physical association of POSS end-groups was designed to reinforce shear-thinning hydrogels, and their shear-thinning and recovery properties remained unchanged.

Reversible monolayer-to-crystalline phase transition in amphiphilic silsesquioxane at the air-water interface

We report on the counter intuitive reversible crystallisation of two-dimensional monolayer of Trisilanolisobutyl Polyhedral Oligomeric SilSesquioxane (TBPOSS) on water surface using synchrotron x-ray scattering measurements. Amphiphilic TBPOSS form rugged monolayers and Grazing Incidence X-ray Scattering (GIXS) measurements reveal that the in-plane inter-particle correlation peaks, characteristic of two-dimensional system, observed before transition is replaced by intense localized spots after transition. The measured x-ray scattering data of the non-equilibrium crystalline phase on the air-water interface could be explained with a model that assumes periodic stacking of the TBPOSS dimers. These crystalline stacking relaxes upon decompression and the TBPOSS layer retains its initial monolayer state. The existence of these crystals in compressed phase is confirmed by atomic force microscopy measurements by lifting the materials on a solid substrate.

POSS-induced enhancement of mechanical strength in RAFT-made thermoresponsive hydrogels

In this study, covalently cross-linked thermoresponsive hydrogels were prepared with higher mechanical stability by the introduction of polyhedral oligomeric silsesquioxane (POSS) moieties.