Smart pH-Sensing Chitosan-Carbon Quantum Dot Hydrogel and Microneedle for Wound Diagnostic Application

Abstract Inspired by the wound healing challenges, we reported a chitosan(CS)-derived hydrogel integrated with carbon quantum dots (CQDs) focusing on a biochemical−mechanical regulation synergistic strategy. The modification of CS’s hydrogel matrix by optimized CQD concentration brings a platform with balanced swelling property, mechanical flexibility, and surface properties. CQDs act as interstitial nanofillers that aid in shrinking the CS pore size from ∼160 μm to ∼37 μm, which makes them ideal to prevent leaching and ensure controlled release of bioactive agents. The incorporation of CQDs in the hydrogel matrix improves the tensile strength up to 1.2-fold, increases the swelling by 5-fold, and enhances the spreading ability to 9.12°/min. It also upgrades Young’s modulus to 2.11 MPa while recovering a high stretchability of 81%. The molecular architecture and its dynamic behavior were analyzed using computation, which highlights the role of hydrogen bonds. The IC50 values for the CQD-assisted system against HDF cell lines range from 105 to 135 μg/mL, indicating cytocompatibility. We observed a high cell migration rate of 25.6 μm/h with HDF fibroblast migration, which is four-fold higher than that of pure CS (6.6 μm/h) through the scratch assay. Further, the formulation demonstrates good antibacterial activity against both Gram-positive bacteria (Staphylococcus aureus; ∼71%) and Gram-negative bacteria (Escherichia coli; ∼73%), compared to the positive control ciprofloxacin. It enhances cell proliferation and accelerates regeneration in an optimal moist environment at the wound site, creating a protective and bioactive environment that is biocompatible and antimicrobial. Furthermore, we demonstrated, quantitatively, the pH responsiveness of the hydrogel and pH sensing applications of microneedles. The smart alkaline-triggered sensing behavior will be effective in building a diagnostic system for microbial colonization and wound healing application.