“Green” gas-generation strategy to combine cancer phototherapy for remarkably enhanced efficacy

Abstract

Phototherapy, which mainly includes photodynamic therapy (PDT) and photothermal therapy (PTT), has made considerable progress in the field of cancer treatment by generating reactive oxygen species or hyperthermia under photorespiration to selectively damage cancer cells. However, PDT or PTT monotherapy still needs to overcome the respective limitations for biosafety and efficacy improvement. Gas therapy, especially guided by photoacoustic imaging, is an emerging therapeutic approach that destroys cancer cells by increasing the levels of certain gases at the tumor site, wherein some gas molecules can not only increase the O₂ level by cellular respiration inhibition and nanoparticles accumulation by controlled release but also inhibit HSP expression and hyperthermia-induced inflammation. Hence, combining various gases with phototherapy and hyperthermia-induced photoacoustic imaging to achieve superlatively superimposed therapeutic outcomes has received increasing attention due to its unique biological functions. In this review, gas molecular monotherapy is initially summarized, followed by a comprehensive overview of the latest research advances in gas-assisted phototherapy or photoacoustic imaging, finally exploring the prospects and challenges of gas therapy to fight cancer. Recent research advances are summarized, providing innovative perspectives on the design of cancer phototherapy or photoacoustic imaging combined with gas therapy to further improve the therapeutic outlook.