Mussel-Inspired Adhesive Hydrogels Based on Laponite-Confined Dopamine Polymerization as a Transdermal Patch.

Transdermal patch for local drug delivery has attained huge attention as an attractive alternative to existing drug delivery techniques as it is painless and user-friendly. However, most adhesive hydrogels either do not have adequate adhesion with the skin or cause discomfort while being removed from the skin surface due to excessive adhesion. To address this challenge, we developed an adhesive hydrogel based on laponite-confined dopamine polymerization as a transdermal patch. Laponite RDS nanoclay was used to control the hydrogel's viscous behavior and dopamine polymerization. The laponite polymerized polydopamine (l-PDA) was incorporated into poly(vinyl alcohol) (PVA) to make the PVA-l-PDA hydrogel. The laponite-confined polymerization improved the hydrogels' water contact angle and adhesion strength. The adhesion strength of the PVA-l-PDA hydrogel was adequate to adhere to the evaluated goat skin, glass, and polypropylene surfaces. Notably, the PVA-l-PDA hydrogel was easy to peel off from the skin. Further, we evaluated the drug release profile in goat skin using lidocaine as a model drug. We observed the controlled release of lidocaine from the PVA-l-PDA hydrogel compared to the PVA-PDA hydrogel. In addition, the nanoclay-confined adhesive hydrogel did not show any cytotoxic effect in fibroblasts. Altogether, PVA-l-PDA hydrogels offer appropriate adhesive strength, toughness, and biocompatibility. Thus, the PVA-l-PDA hydrogel has the potential to be an efficient transdermal patch.

Silica Release from Silane Cross-Linked Gelatin Based Hybrid Scaffold Affects Cell Proliferation.

Earlier, we had reported the synthesis and characterization of star-shaped poly(d,l-lactide)-b-gelatin (ss-pLG) to improve cell adhesion and proliferation, but the stability of ss-pLG scaffolds remained a persistent issue. Here we show an increase in the stability of ss-pLG using 3-glycidoxypropyl trimethoxysilane (GPTMS) as a covalent cross-linker (h-ss-pLG). The rate of cell proliferation within Hep-G2 cultured h-ss-pLG scaffolds increased until the third day, and afterward it drastically declined. Further, we identified the release of inorganic silica from GPTMS cross-linked h-ss-pLG, which may be associated with the decrease in the rate of HepG2 cell proliferation. However, the cross-linking did not affect red blood cells (RBCs) and they were completely hemocompatible. In addition, our in vivo experiments in female rats showed that the hybrid h-ss-pLG scaffolds were not degraded completely after 4 weeks, as they were covalently cross-linked with silane. These results suggest the significance of the cross-linker selection, which is one of the other key factors, and needs to be considered while designing scaffolds.