Interfacial Engineering of High-Performance Upconversion Hydrogels with Orthogonal NIR Photochemistry in Vivo for Synergistic Noninvasive Biofilm Elimination and Tissue Repair

Abstract

NIR-mediated upconversion photochemistry stands as a powerful tool for noninvasive tissue engineering with excellent depth penetration. However, challenges such as low NIR upconversion and photochemical efficiencies, coupled with the moderate mechanical properties of upconversion hydrogels, hinder their advanced applications, particularly in oxygen- and water-rich physiological environments. This study addresses these limitations by strategically considering the interfacial effect and implementing a well-thought-out design for rapid NIR-mediated upconversion photochemistry, thereby developing high-performance upconversion hydrogels in vivo. Leveraging strong hydrophobic and electrostatic interactions at the interface of upconversion nanoparticles and hydrogel matrices enables us to achieve a remarkable 6-fold increase in fluorescent upconversion emission. This strategic enhancement in NIR photochemistry facilitates the rapid one-step formation of hierarchical upconversion hydrogels deep within tissues, significantly reducing fabrication time from approximately 6 min to 45 s. Meanwhile, these stretchable tough upconversion hydrogels experience impressive increases in mechanical properties by 3–10 times. Such rapid and controllable NIR photochemistry is compatible with standard printing techniques, allowing for the remote fabrication of complex structures beneath the skin. Moreover, as-prepared biocompatible upconversion hydrogels exhibit enhanced antimicrobial activity, surpassing typical bacteria, such as Escherichia coli and Staphylococcus aureus. With these notable advantages, the potential of this upconversion photochemistry extends beyond tissue engineering to include synergistic noninvasive biofilm elimination and tissue repair. Its promising applications span diverse fields, encompassing photochemistry, materials, engineering, and information sciences.