Light-Induced Caspase-3-Responsive Chimeric Peptide for Effective PDT/Chemo Combination Therapy with Good Compatibility.

Activated doxorubicin (DOX) often has severe systemic toxicity and side effects due to its inability to distinguish tumor cells from normal cells, which seriously affects the prognosis of patients. Here, we synthesized an inactivated a DOX prodrug that could be selectively activated by a light-induced caspase-3 enzyme in the tumor site. In the absence of light, this uniformly dispersed nanoparticle avoided the unnecessary toxicity under physiological conditions. Upon the laser irradiating to the tumor area of interest, the nanoparticles can produce a large amount of reactive oxygen species (ROS) to induce cell apoptosis and activate caspase-3 enzyme to release DOX selectively. Meanwhile, the produced ROS can also combine with activated DOX to cause more potent tumor damage. The experiments demonstrated that the light can effectively activate DOX drug through a series of cascade events and the subsequent synergistic therapy both in vitro and in vivo. This strategy achieved excellent therapeutic outcomes and minimal adverse effects, which should significantly improve the dilemma of traditional chemotherapy.

Tumor-triggered transformation of chimeric peptide for dual-stage-amplified magnetic resonance imaging and precise photodynamic therapy.

Despite the great success in clinical magnetic resonance imaging (MRI), Gd3+-based contrast agents still suffer from low proton relaxation efficiency, rapid metabolic clearance as well as poor sensitivity. In this work, we designed a matrix metalloproteinase-2 (MMP-2) responsive chimeric peptide for dual-stage-amplified MRI and precise photodynamic therapy. Both in vitro and in vivo studies indicated that this chimeric peptide could self-assembly into spherical nanoparticles at physiological condition with r1 value of 28.17 mM-1s-1. Meanwhile, the spherical shape endowed chimeric peptide with efficient tumor accumulation via enhanced penetration and retention (EPR) effect. Importantly, the overexpressed MMP-2 in tumor region could specifically hydrolyze chimeric peptide, leading to sphere-to-fiber transformation. This transformation enhanced both the tumor accumulation and the relaxivity of contrast agent. Consequently, the r1 value was remarkably elevated to 51.52 mM-1s-1, which guided precise photodynamic therapy. This tumor microenvironment-triggered transformable strategy should show great potential for tumor-targeted imaging and phototherapy.