Facile wound dressing replacement: Carbon dots for dissolving alginate hydrogels via competitive complexation

Dissolvable hydrogels have shown great potentials in removing the exudes and alleviating pain during wound dressing replacement. Herein, a series of carbon dots (CDs) composing high complexation ability with Cu2+ were prepared for capturing Cu2+ from Cu2+-alginate hydrogels. CDs were prepared using biocompatible lysine as the main starting material, while ethylenediamine was chosen as the other starting material for its extremely high complexation ability with Cu2+. The complexation ability increased with the increasing amount of ethylenediamine, while the cell viability decreased. When the mass ratio of ethylenediamine to lysine in CDs was above 1/4, six-coordinate copper centers could be formed. CD1/4 at the concentration of 90 mg/mL could dissolve Cu2+-alginate hydrogels within 16 min, which was about twice faster than lysine. In vivo results showed the replaced hydrogels could ameliorate hypoxic conditions, alleviate local inflammatory reactions and promote the healing speed of burn wounds. Thus, the above results suggested the competitive complexation of CDs with Cu2+ could effectively dissolve Cu2+-alginate hydrogels, which have much potential in realizing facile wound dressing replacement.