An activatable photoacoustic probe for imaging upregulation of hydrogen sulfide in inflammation

Inflammation is a response to traumatic, infectious, toxic, or autoimmune injury, and uncontrolled inflammation can lead to diseases such as cardiovascular and cerebrovascular disease, fibrosis, and cancer. Hydrogen sulfide (H2S) acts as an extremely important mediator of inflammation. As photoacoustic (PA) imaging can conduct high spatial resolution imaging while maintaining high contrast of optical imaging, it has shown great potential for clinical applications in disease microenvironment imaging, tumor imaging, and real-time drug imaging. However, the activatable PA probes for imaging of H2S levels in mice to detect inflammatory mediators have not yet developed. Herein, we have designed a novel activatable near-infrared (NIR) photoacoustic probe (PAP-H2S) with a specific response H2S, where the PA signal is turned on at 715 nm and the absorption wavelength is redshifted up to 165 nm. Meanwhile, it could be observed that PAP-H2S shows a 9.2-fold PA signal enhancement after being activated by H2S. Significantly, PAP-H2S was the first probe to monitor H2S levels in a mouse air pouch inflammation model by PA imaging technology. We expect PAP-H2S to become an effective tool for the diagnosis and monitoring of related diseases due to the development of inflammation in vivo.