Development of a nitric oxide sensor for in vitro evaluation of the capsaicin's anti-inflammatory activity

An integrated nitric oxide (NO) sensor was developed based on a three-dimensional cell culture system. The anti-inflammatory activity of capsaicin was evaluated by monitoring NO levels in the supernatant under three operational modes, where lipopolysaccharide (LPS) induced NO production in cells, and capsaicin suppressed this production. The sensor employs methacryloylated gelatin hydrogel to encapsulate RAW264.7 cells, which serve as the bioactive component, and incorporates an ionic liquid film/antimony tetroxide/reduced graphene oxide (DDAB-RTIL/Sb₂O₄/rGO) onto a screen-printed carbon electrode. This system demonstrates enhanced selectivity for NO. Under optimized experimental conditions, NO was specifically detected using differential pulse voltammetry (DPV), which exhibited a linear range of 3.14-42.58 μmol/L and a detection limit of 0.77 µmol/L. Following LPS-induced treatment at 1 µg/mL, the DPV peak current reached 100%, while treatment with 5 µM capsaicin resulted in a peak current of I₅. The co-treatment mode (58.8%) exhibited a higher peak current than both the therapeutic mode (74.5%) and the preventive mode (91.9%). This study offers a practical method for in vitro evaluation of capsaicin's anti-inflammatory activity.