On June 18, 2024, a team led by Sun Siyu, Sun Guangwei, and Liu Yang from Shengjing Hospital affiliated with China Medical University published a paper titled "Injectable chitosan polyvinylpyrrolidone composite thermosensitive hydrogels with sustained subject lifting for endoscopic subject section" online in the International Journal of Biological Macromolecules. The team developed a high pH chitosan solution (HpHCS) in the early stage, which confirmed that this solution has a high degree of deprotonation and can significantly improve the speed of thermosensitive gelation (European Polymer Journal 2023, 196, 112, 229.). On this basis, this study further constructed a new injectable composite thermosensitive hydrogel system with lower viscosity, better gel integrity and stability - high pH chitosan polyvinylpyrrolidone - β - glycerophosphate sodium (HpHCS-PVP-GP).

The core product of Changguang Chenying HOOKE P300 pro laser confocal Raman spectrometer is lucky to provide a powerful research tool for the analysis of the construction mechanism of the new HpHCS-PVP-GP gel in this study.

Abstract

To develop a submucosal injection material with sustained submucosal lifting for endoscopic submucosal dissection (ESD), this study designed and prepared a novel composite thermosensitive hydrogel system with high pH chitosan-polyvinylpyrrolidone-β-glycerophosphate (HpHCS-PVP-GP). HpHCS improved the injectability of the hydrogels and retained the rapid gelation ability at low concentrations. The modification of PVP significantly improved the stability of low-temperature hydrogel precursor solutions and the integrity of hydrogels formed at 37 °C through hydrogen bonds between PVP and HpHCS. A mathematical model was established using response surface methodology (RSM) to evaluate the synergistic effect of HpHCS, GP, and PVP concentrations on gelation time. This RSM model and submucosal lifting evaluation using in vitro pig esophageal models were used to determine the optimal formula of HpHCS-PVP-GP hydrogels. Although the higher PVP concentration (5 % (w/v)) prolonged gelation time, it improved hydrogel mechanical strength, resulting in better submucosal lifting performance. The experiments of Bama mini pigs showed that the heights of the cushions elevated by the HpHCS-5%PVP-GP hydrogel remained about 80 % 1 h after injection. Repeated injections were avoided, and the hydrogel had no cytotoxicity after electric cutting. Therefore, the HpHCS-PVP-GP thermosensitive hydrogel might be a promising submucosal injection material for ESD.

Keywords: Chitosan; Polyvinylpyrrolidone; Thermosensitive hydrogel.

The paper links：https://www.sciencedirect.com/science/article/abs/pii/S0141813024039709