Investigating the absorbent properties of carboxymethyl cellulose-chitosan‑carbon dots nanocomposite sponge using photoacoustic microscopy.

Recently, sponge biopolymers containing nanoparticles have attracted attention for the preparation of wound-healing products such as wound dressings. Due to the optically non-transparent nature of nanocomposite sponges, only limited microscopic methods have been used to investigate the structural changes caused by adding nanomaterials. The use of various microscopic characterization methods can lead to a better understanding of the performance of nanomaterials in improving the properties of polymer sponges. In this study, photoacoustic microscopy (PAM) imaging was used as a 3D imaging technique to visualize blood penetration and spreading in the fabricated nanocomposite sponges. To form a sponge nanocomposite, carboxymethylcellulose/chitosan (CMC/CS) biopolymers are bonded to green-synthesized carbon dots (CD). The results showed that adding CD to CMC/CS biopolymer and forming CMC/CS/CD nanocomposites caused changes in the cavity structure, resulting in increased porosity and more water absorption and retention, which was better for fluid absorption and therefore more helpful for wound dressing applications. In addition, an investigation of blood penetration and its distribution by PAM showed that by adding CD to composite sponges, blood penetration, diffusion, and absorption increased. Based on these findings, using CD and CMC/CS together can improve the physicochemical properties of sponge nanocomposites, making them ideal for wound dressing.