Photodynamic therapy-triggered on-demand drug release from ROS-responsive core-cross-linked micelles toward synergistic anti-cancer treatment

Polymeric micelles have demonstrated wide utility for chemodrug delivery,which however,still suffer from shortcomings such as undesired drug loading,disassembly upon dilution,pre-leakage of drug cargoes during systemic circulation,and lack of cancer-selective drug release.Herein,a poly(ethylene glycol)(PEG)-polyphosphoester-based,reactive oxygen species (ROS)-responsive,core-cross-linked (CCL) micellar system was developed to encapsulate both chemodrug (doxorubicin,Dox) and photosensitizer (chlorin e6,Ce6).The hydrophobic core of the micelles was cross-linked via a thioketal (TK)-containing linker,which notably enhanced the drug loading and micelle stability.In tumor cells,far-red light irradiation of Ce6 generated ROS to cleave the TK linkers and disrupt the micelle cores.As such,micelles were destabilized and Dox release was promoted,which thereafter imparted synergistic anti-cancer effect with ROS-mediated photodynamic therapy.This study provides an effective approach to realize the precise control over drug loading,formulation stability,and cancer-selective drug release using polymeric micelles,and would render promising utilities for the programmed anti-cancer combination therapy.

Cardiomyocyte-targeted anti-inflammatory nanotherapeutics against myocardial ischemia reperfusion (IR) injury

Myocardial ischemia reperfusion(IR)injury is closely related to the overwhelming inflammation in the myocardium.Herein,cardiomyocyte-targeted nanotherapeutics were developed for the reactive oxygen species(ROS)-ultrasensitive co-delivery of dexamethasone(Dex)and RAGE small interfering RNA(siRAGE)to attenuate myocardial inflammation.PPTP,a ROSdegradable polycation based on PGE2-modified,PEGylated,ditellurium-crosslinked polyethylenimine(PEI)was developed to surface-decorate the Dex-encapsulated mesoporous silica nanoparticles(MSNs),which simultaneously condensed siRAGE and gated the MSNs to prevent the Dex pre-leakage.Upon intravenous injection to IR-injured rats,the nanotherapeutics could be efficiently transported into the inflamed cardiomyocytes via PGE2-assisted recognition of over-expressed E-series of prostaglandin(EP)receptors on the cell membranes.Intracellularly,the over-produced ROS degraded PPTP into small segments,promoting the release of siRAGE and Dex to mediate effective RAGE silencing(72%)and cooperative antiinflammatory effect.As a consequence,the nanotherapeutics notably suppressed the myocardial fibrosis and apoptosis,ultimately recovering the systolic function.Therefore,the current nanotherapeutics represent an effective example for the codelivery and on-demand release of nucleic acid and chemodrug payloads,and might find promising utilities toward the synergistic management of myocardial inflammation.