Synergy of light-controlled Pd nanozymes with NO therapy for biofilm elimination and diabetic wound treatment acceleration

The presence of bacteria, existing as highly organized biofilm communities, in chronic non-healing wounds has been identified as a significant impediment for wound healing. Nanozymes, with unique antimicrobial mechanisms, as a new alternative for antibiotics, have the potential to synergize with nitric oxide (NO) with enhanced antibacterial and antibiofilm ability. However, the always-on state of nanozymes and the reactivity of NO limit their clinical applications. In this context, an intelligent and multifunctional Pd-MOF@PAzo@SNP nanoplatform was fabricated using UiO-66 as a palladium (Pd) nanozyme-loading vehicle, then a surface modification with photosensitive polyazobenzene (PAzo), and the adsorption of the NO donor sodium nitroprusside (SNP) via a host-guest interaction between β-cyclodextrin-modified hyaluronic acid (β-CD-HA) and azobenzene. The activity of Pd-nanozyme was easily controlled via ultraviolet (UV) light, and its photosensitivity was regulated by changing the side-chain unit length of PAzo. Furthermore, NO was released in response to the UV irradiation and played a synergistic role with the peroxidase activity of Pd nanozyme, exhibiting excellent antibacterial and antibiofilm activity in the presence of 0.01 mM hydrogen peroxide (H2O2). In vivo, Pd-MOF@PAzo@SNP accelerated the healing of a biofilm-infected diabetic wound by dispersing the biofilm, reducing bacterial burden, and promoting angiogenesis and collagen deposition. Overall, the nanoplatform provides a reliable and highly efficient strategy to develop an intelligent nanozyme synergy with NO therapy in chronic wound management.