A novel hydrogel-coated chest drain based on ropivacaine-glycerol-alginate hydrogel with construction and application to postoperative thoracic rehabilitation

<b>Study objectives:</b> We aimed to develop a drug-loaded hydrogel-encapsulated chest drain to improve postoperative comfort and recovery in thoracic surgery patients. <b>Methods:</b> The hydrogel was modified with different ratios of glycerol and alginate, then mixed with varying concentrations of ropivacaine and fixed on a simulated chest drain tube using a mould and calcium chloride solution. The morphology, degradation, and slow-release properties of the hydrogel were assessed to identify the most suitable formulation. A bacteriostatic test was conducted using bacterial smear plates. The new chest drain was then implanted in rats using the seldinger method. Pathological changes were observed with imaging techniques such as chest ultrasound and radiographs, while lung function was assessed to evaluate the analgesic effect. After the animal experiments, hematoxylin and eosin (H&E) and Masson staining were performed on relevant tissues to analyze inflammation, and SOD activity was measured to assess oxidative stress levels. <b>Results:</b> The optimal drug-loaded hydrogel for chest drains contained 2% sodium alginate, 10% glycerol, and ropivacaine concentrations between 0.25% and 0.75%. This formulation showed superior morphological characteristics, degradation, and sustained-release properties. It also exhibited excellent bacteriostatic effects. The low-concentration (0.25%) drug-loaded hydrogel demonstrated better analgesic, anti-inflammatory, and oxidative stress-inhibitory effects in animal studies. <b>Conclusions:</b> The modified ropivacaine-alginate hydrogel-encapsulated chest drain offers a promising local slow-release strategy and may contribute to rapid rehabilitation in thoracic surgery.