Luminescent Imaging And Visual Biosensors Based On Porous Silicon

Luminescent porous silicon(LuPSi)is a promising material for biomedical applications owing to its tunable porosity and surface chemistry,as well as its biocompatibility and degradability into nontoxic orthosilicic acid.The luminescence of LuPSi could be quenched under oxidation process.These properties have led to the application of LuPSi as optical biosensors for bio-imaging and drug delivery.This work is based on the luminescence,drug loading and biocompatibility characters of porous silicon.It mainly includes the following two parts:(1)The p type luminescent porous Si can quench the loaded luminescent dye due to fluorescence resonance energy transfer(FRET)effect.However,when the PSi is oxidized by oxidation species,the fluorescence of PSi could be quenched because of the elimination of quantum-confined Si domains,and the FL of dye will recover since the generated SiO2 layers block FRET effect.It can be a ratiometric FL intensity change under oxidation process.Herein,we loaded CIP into LuPSi to construct a dual-fluorescence system(CIP-PSi).Furthermore,we integrated CIP-PSi particles into polyurethane(PU)membrane as a smart bandage for wound monitoring and wound cure.The visual color change from red to blue of smart bandage in the wound environment helped us to distinguish between infected wounds and acute wounds.In the meantime,the released CIP killed the S.aureus(ATCC 25923)in the infected wounds and improved wound cure.(2)The quick oxidation of n type porous silicon under irradiation by oxidation species(O2?H2O2)can cause irreversible fluorescence quenching.It is because of the defect energy levels of SiO2 and the elimination of quantum-confined Si domains.Herein,we developed an exposure quenching imaging technology for two mainly applications.One is mask imaging for anti-counterfeit label,the other is spatial distribution of H2O2 for ROS analysis in plant tissue.