Broad-Spectrum Bactericidal Multifunctional Tiny Silicon-Based Nanoparticles Modified with Tannic Acid for Healing Infected Diabetic Wounds

Infected chronic wounds, in particular, diabetic wounds, are hard to heal, posing a global health concern with high morbidity and mortality rates. Diabetic full-thickness wounds infected with E. coli belong to the most difficult to heal chronic infected wounds. Here, we introduced tannic acid-modified silicon-based nanoparticles (TA-SiNPs) with broad-spectrum bactericidal activity that bacteria develop minimal resistance to, and they can effectively treat full-thickness wounds in diabetic mice infected with E. coli. Our findings indicate that these TA-SiNPs could achieve 100% antibacterial efficiency against S. aureus and 99.83% against E. coli, underlied by a positive surface charge and tannic acid groups facilitating bacterial membrane chemical composition depletion and depolarization of the membrane. In addition, we showed that spraying TA-SiNPs onto the skin wound of diabetic mice infected with E. coli resulted in wound healing with 98% closure after 12 days, in stark contrast to 49% of the control (PBS) and 68% of the one treated with Ofloxacin. Along with infection inhibition and ROS scavenging, we identified cell proliferation stimulation, inflammatory cytokine downregulation, and healing cytokine upregulation in the lesion, favoring the healing process. This study not only demonstrates the feasibility of employing silicon-based nanoparticles in diabetic wound healing for the first time, but also reports the first broad-spectrum bactericidal silicon nanodots. Furthermore, this provides novel insights into the mechanism of tannin-based nanoparticles disrupting bacterial membranes by depleting their chemical constituents. Our results highlighted that the developed TA-SiNPs are an effective nanomaterial for treating the infected chronic wounds.