Yanyan Huang

Graphitic carbon nitride (g-C3 N4 ) has been used as photosensitizer to generate reactive oxygen species (ROS) for photodynamic therapy (PDT). However, its therapeutic efficiency was far from satisfactory. One of the major obstacles was the overexpression of glutathione (GSH) in cancer cells, which could diminish the amount of generated ROS before their arrival at the target site. Herein, we report that the integration of Cu(2+) and g-C3 N4 nanosheets (Cu(2+) -g-C3 N4 ) led to enhanced light-triggered ROS generation as well as the depletion of intracellular GSH levels. Consequently, the ROS generated under light irradiation could be consumed less by reduced GSH, and efficiency was improved. Importantly, redox-active species Cu(+) -g-C3 N4 could catalyze the reduction of molecular oxygen to the superoxide anion or hydrogen peroxide to the hydroxyl radical, both of which facilitated the generation of ROS. This synergy of improved ROS generation and GSH depletion could enhance the efficiency of PDT for cancer therapy.

A new red-emissive bioprobe TPE-red-2AP2H was developed by taking advantage of the unique emission feature of tetraphenylethylene and a cancer cell-specific peptide. By responding to the target protein and the acidic microenvironment of tumor cells, activated fluorescence bioimaging was achieved with high signal-to-noise ratio and without involving mutiple washing steps. Apart from targeting the membrane-anchored LAPTM4B proteins, TPE-red-2AP2H was successfully utilized to trace the intracellular movement of LAPTM4B protein. The generation of (1)O2 under visible light irradiation makes this bioprobe also promising for targeted-photodynamic therapy. By discriminating the expression level of the target protein, TPE-red-2AP2H can respond to the progression status of tumors with different photodynamic therapy effect.

Prodrug activation, by exogenously administered enzymes, for cancer therapy is an approach to achieve better selectivity and less systemic toxicity than conventional chemotherapy. However, the short half-lives of the activating enzymes in the bloodstream has limited its success. Demonstrated here is that a tyrosinase-MOF nanoreactor activates the prodrug paracetamol in cancer cells in a long-lasting manner. By generating reactive oxygen species (ROS) and depleting glutathione (GSH), the product of the enzymatic conversion of paracetamol is toxic to drug-resistant cancer cells. Tyrosinase-MOF nanoreactors cause significant cell death in the presence of paracetamol for up to three days after being internalized by cells, while free enzymes totally lose activity in a few hours. Thus, enzyme-MOF nanocomposites are envisioned to be novel persistent platforms for various biomedical applications.

For the development of multistimuli responsive organogels, the new organic gelator LMWG 1, featuring electroactive TTF and photoresponsive azobenzene groups, was designed and studied. By manipulating the redox state of the TTF group in LMWG 1, the gel−sol transition for organogels with the LMWG 1 can be reversibly tuned by either chemical or electrochemical oxidation/reduction reactions. Alternatively, the photoisomerization of the azobenzene group in LMWG 1 can also trigger the gel−sol transition. Therefore, organogels with LMWG 1 respond not only to thermal stimuli but also to redox reactions and light irradiation.

Herein, a new fluorescence turn-on chemosensor 2-(4-(1,2,2-triphenylvinyl)phenoxy)acetic acid (TPE-COOH) specific for Al(3+) was presented by combining the aggregation-induced-emission (AIE) effect of tertaphenylethylene and the complexation capability of carboxyl. The introduction of carboxylic group provides the probe with good water-solubility which is important for analyzing biological samples. The recognition toward Al(3+) induced the molecular aggregation and activated the blue fluorescence of the TPE core. The high selectivity of the probe was demonstrated by discriminating Al(3+) over a variety of metal ions in a complex mixture. A detection limit down to 21.6 nM was determined for Al(3+) quantitation. Furthermore, benefiting from its good water solubility and biocompatibility, imaging detection and real-time monitoring of Al(3+) in living HeLa cells were successfully achieved. The AIE effect of the probe enables high signal-to-noise ratio for bioimaging even without multiple washing steps. These superiorities make this probe a great potential for the functional study and analysis of Al(3+) in complex biosystems.