| Currently,the morbidity and mortality of various diseases are increasing year by year,especially cancer,which have posed a great threat to our health.For example,both dihydronicotinamide adenine dinucleotide（NADH）and glutathione（GSH）are biomarkers of many diseases of humans.Therefore,the realization of early clinical diagnosis and treatment of various diseases is particularly urgent.However,it is difficult for employing the traditional methods and general devices to detect them accurately in the early stage.Optical and photoelectrochemical biosensors can detect biological substances quickly and accurately,even in real time.They have the advantages of high sensitivity,simple and easy operation of equipment,easy preparation of materials and low noise.The development of high-performance optical or photoelectrochemical sensors mainly involves the preparation of highly efficient luminescent nanomaterials and the selection of electrode materials.Based on these,we carried out the following research:1.All-inorganic perovskite quantum dots（PQDs）have attracted tremendous attention due to their extraordinary optical properties,especially CsPbBr3 QDs with their high stability and photoluminescence efficiency.However,studies of the biosensing capabilities based on PQDs are still limited.Herein,we designed a visible-light-triggered photoelectrochemical（PEC）sensor based on CsPbBr3 QDs for the first time.The immobilized three-dimensional（3D）ZnO inverse opal photonic crystals（IOPCs）were applied to dihydronicotinamide adenine dinucleotide（NADH）sensing.It was found that the CsPbBr3 QDs,as a photoactive material in a PEC sensor,can expand the photocurrent response of the PEC sensor to the visible region,as well as boost its conductivity.This PEC sensor based on a ZnO/CsPbBr3 electrode demonstrates sensitive detection of NADH in phosphate buffer saline solution and serum,with a good linear range from 0.1μM to 250μM and a low detection limit of 0.010μM.2.Compared with perovskite quantum dots,rare earth ions doped upconversion nanocrystals（UCNCs）are a kind of important optical materials in biological applications because of their low energy near-infrared excitation wavelength and large anti-Stokes emission,which can effectively improve the signal-to-noise ratio in biosensors.However,low luminescent intensity/efficiency of UCNCs seriously limits its practical application in biodetection.The surface plasmon modulation based on plasmonic metallic nanostructure is a promising way to largely enhance the luminescent intensity/efficiency of UCNCs.Herein,the silver nanowire AgNW/NaYF4:Yb3+,Tm3+composites film was prepared by the simple drop-casting method.An optimum UCL enhancement as high as28 folds for UC visible emission and 5 folds for down-conversion near infrared emission were realized.Systematic experimental studies indicate that the luminescent enhancement is due to excitation filed enhancement instead of Purcell effect.In addition,we explored its biosensing for GSH with the triggering of a near infrared wavelength.3.Intracellular glutathione（GSH）sensing is important for monitoring many diseases and health of cell.Ti3C2 quantum dots have high stability and biocompatibility,easy to surface functionalization,which is conducive to further improving the sensitivity of glutathione sensor and realizing the intracellular glutathione（GSH）sensor.The surface-functionalized Ti3C2 quantum dots（QDs）with the diameter of 10 nm by the sonication cutting and hydrothermal method were prepared.The bright excitation wavelength dependent blue emission was observed in Ti3C2 QDs,which is attributed to the surface defects and quantum confinement effect.Furthermore,we developed a novel fluorescent sensor to high sensitively detect GSH based on fluorescence resonance energy transfer process from Ti3C2 QDs to GSH,the detection limit is approximately0.02μM,with the linear range from 1μM to 100μM.Furthermore,the real-time detection of GSH in cells based on Ti3C2 QDs was also carried out. |
