Trapping and release of NIR-active dye in porous silicon as a theranostic strategy for ROS photothermal monitoring and chronic wound management

Reactive oxygen species (ROS)-sensitive theranostics hold great promise for personalized treatment of various diseases. However, most current theranostics rely on luminescence techniques with complex probe design, high background signals and bulky instruments. Herein, we propose a novel thermal signal-based theranostic for ROS monitoring by detecting the photothermal signal change of near-infrared (NIR)-active dye (IR820) that released from the porous silicon (PSi)-based carrier and demonstrate its application for synergistic theranostics of chronic wounds. Owing to the reduced energy level caused by J-aggregate formation and the improved non-radiative decay pathway, trapping of IR820 in calcium ion sealed PSi (I-CaPSi) exhibits significantly enhanced photothermal capability compared to free IR820. With the degradation of PSi induced by ROS, the trapped and aggregated IR820 is released to be dispersed and free state. Therefore, the decrease of photothermal signal in response to ROS stimuli can be recorded in real time. Using a portable smartphone equipped with a thermal camera, ROS levels at wounds can be monitored non-invasively and conveniently to indicate exacerbation or healing conditions. Moreover, the NIR-triggered smart delivery platform also triggers photothermal and photodynamic therapy to inhibit bacterial growth and exhibits bioactivity to promote cell migration and angiogenesis via the Si ions released from PSi. With the synergistic advantages of ROS-responsive property, pro-healing ability, anti-infection effect and excellent biosafety, the NIR-activated theranostic platform achieves convenient diagnosis and effective treatment in diabetic wound infection models in vivo. Overall, this work demonstrates a promising paradigm of I-CaPSi smart delivery platform with great clinical translation potential for home-based chronic wound theranostics.