A pH indicating carboxymethyl cellulose/chitosan sponge for visual monitoring of wound healing

A type of carboxymethyl cellulose/chitosan composite sponge that is able to indicate pH changes was prepared and characterized. This sponge, dyed with the natural dye cyanine, showed a rather rapid response by changing from blue to green as the solution pH changed from 4 to 8. This visible color change indicated that the sponge could be a pH sensor with high sensitivity. The carboxymethyl cellulose/chitosan composite sponges exhibited a good air permeability and high porosity because the sponge's pores were all open and interconnected. The porosity, the moisture vapor transmission rate, and the water vapor permeability all increased as the chitosan content increased. The chitosan microparticles added in carboxymethyl cellulose reinforced the composite sponge and improved its antibacterial activity. The cyanine dyed carboxymethyl cellulose/chitosan sponges have substantial potential as wound-healing monitors.