Boosting phototherapy efficacy of NIR-absorbing ruthenium (II) complex via supramolecular engineering

Molecular aggregation of a well-designed photosensitizer has the potential to minimize its energy gap (ΔEST), thereby promoting the intersystem crossing rate, as well as singlet oxygen (1O2) generation. In light of this characteristic, a supramolecular photosensitizer (RuFF-NPs) has been fabricated through the noncovalent interaction of a Ru(II)-based complex (RuTP) and diphenylalanine peptide (FF). In contrast to the monomer of RuTP, RuFF-NPs showed excellent water dispersity, aggregation-enhanced 1O2 generation, remarkable red-shifted absorption, improved biocompatibility, and efficient dual phototherapeutic performance, which are highly desired characteristics for phototherapy. In cancer phototherapy, RuFF-NPs exhibited a much high tumor growth inhibition rate of 95.3% in vivo. Conspicuously, the tumor penetration and spatial distribution of RuFF-NPs with time were visually imaged at the molecular level, and the potential biochemical response was demonstrated, providing valuable information for elucidating the underlying anticancer mechanisms of phototherapy.