Cationic telluroviologen derivatives as type-I photosensitizers for tumor photodynamic theranostics

The hypoxia of the tumor microenvironment(TME)seriously restricts the photodynamic therapy(PDT)effect of conventional type-II photosensitizers,which are highly dependent on O_(2).In this work,a new type-I photosensitizer(TPE-TeVPPh3)consisting of a tetraphenylethylene group(TPE)as a bioimaging moiety,triphenyl-phosphine(PPh3)as a mitochondria-targeting group,and telluroviologen(TeV2+)as a reactive oxygen species(O_(2)•−,•OH)generating moiety is developed.The luminescence intensity of TPE-TeV-PPh3 increased significantly after specific oxidation by excess H2O2 in the TME without responding to normal tissues via the formation of Te═O bond,which can be used for monitoring abnormal H2O2,positioning,and imaging of tumors.TPE-TeV-PPh3 with highly reactive radicals generation and stronger hypoxia tolerance realizes efficient cancer cell killing under hypoxic conditions,achieving 88%tumor growth inhibition.Therefore,TPE-TeV-PPh3 with low phototoxicity in normal tissue achieves tumor imaging and effective PDT toward solid tumors in response to high concentrations of H_(2)O_(2)in the TME,which provides a new strategy for the development of type-I photosensitizers.

Fluorine-defects induced solid-state red emission of carbon dots with an excellent thermosensitivity

Up to date,solid-state carbon dots(CDs)with bright red fluorescence have scarcely achieved due to aggregation-caused quenching(ACQ)effect and extremely low quantum yield in deep-red to near infrared region.Here,we report a novel fluorine-defects induced solid-state red fluorescence(λ_(em)=676 nm,the absolute fluorescence quantum yields is 4.17%)in fluorine,nitrogen and sulfur co-doped CDs(F,N,S-CDs),which is the first report of such a long wavelength emission of solid-state CDs.As a control,CDs without fluorine-doping(N,S-CDs)show no fluorescence in solid-state,and the fluorescence quantum yield/emission wavelength of N,S-CDs in solution-state are also lower/shorter than that of F,N,S-CDs,which is mainly due to the F-induced defect traps on the surface/edge of F,N,S-CDs.Moreover,the solid-state F,N,S-CDs exhibit an interesting temperature-sensitive behavior in the range of 80-420 K,with the maximum fluorescence intensity at 120 K,unveiling its potential as the temperature-dependent fluorescent sensor and the solid-state light-emitting device adapted to multiple temperatures.

Kinetics of Catalyzed Thermal Degradation of Polylactide and Its Application as Sacrificial Templates

Polylactide(PLA)is an outstanding sacrificial template material for the manufacture of microchannels in a thermosetting matrix.However,the initial thermal degradation temperature of pure PLA is relatively high(about 280℃),which limits its use as a sacrificial template.In this report,we found that TBD,an organic base catalyst,can significantly reduce the thermal degradation temperature of PLA.TBD has higher catalytic activity for the thermal degradation of PLA compared with Tin(II)oxalate(Sn(Oxa)),one catalyst reported in the literature.Moreover,the gaseous products catalyzed by TBD for PLA thermal degradation are mainly lactide,and the formation temperature of the monomer is lower and the yield is higher,which may have potential value for PLA recycling.A combined catalyst,S8T2,was composed of 80%low activity catalyst Sn(Oxa)and 20%high activity catalyst TBD,which can catalyze the rapid degradation of PLA without greatly damaging the mechanical properties of PLA.PLA-S8T2 sacrificial fibers can form high-precision one-dimensional microchannels in the epoxy resin matrix,and 3D-printed PLA-S8T2 sacrificial templates can be used to form three-dimensional microchannels in a thermosetting matrix by vaporization of sacrificial components process(VaSC).These features highlight the great potential of PLA-S8T2 as sacrificial template material for the preparation of the complicated microchannels in the thermosetting matrix.