Design,Construction And Applications Of Fluorescence Biosensors Based On Functional Nanomaterials

Nanomaterials are widely used in medicine,catalysis,sensing and other fields because of their unique characteristics.In this dissertation,two different fluorescent sensors were constructed by different types of functional nanomaterials for the detection of specific targets.（1）Firstly,a metal nanomaterial,silver nanoclusters（Ag NCs）were used as signals to establish a multi-color biosensor for adenosine triphosphate（ATP）detection.Content of ATP is an essential index in the development of various diseases.Here we report a ratiometric fluorescent biosensor for ATP based on multi-color Ag NCs.This nanosystem contains two core components:a hairpin DNA integrated with an ATP aptamer,an anchor sequence and a special template segment for synthesis of green-emitting Ag NCs;a single-stranded DNA（ss DNA）which is incompletely complementary with the anchor sequence.Upon exposure to the target,formation of the ATP/aptamer complexes opens the hairpin structure and releases the anchor sequence to hybridize with the ss DNA,accompanied by the“turn-off”of the green fluorescence and“turn-on”of the red fluorescence.By measuring the fluorescence intensity ratio of the two signals,we successfully established a ratiometric biosensor which exhibits sensitive and accurate assay performance toward ATP,with the limit of detection（LOD）as low as 0.38μM.Meanwhile,this ratiometric biosensor shows stable recovery in real sample assay,indicating their potential promise in practical applications.（2）Secondly,mesoporous silica nanoparticles（MSNs）were used as solid matrix for a novel Eu（III）functionalized sensor toward levofloxacin（LVFX）.LVFX is an extensively used fluoroquinolone antibiotic,may enter the ecological cycle and cause damage to creatures and environment.Herein,we report an ammoniated MSNs functionalized with Eu（III）to fabricate fluorescent sensor for optical sensor for LVFX,which used Eu³⁺as signal reporter.The luminescence of Eu³⁺@Am-MSNs can be effectively turned on by LVFX via a fluorescent resonant energy transfer process,thus achieving its recognition of LVFX.Significantly,the fabricated platform(Eu³⁺@Am-MSNs)exhibits outstanding performances for rapid qualitative（within 50 s）and quantitive（ppb level）recognition of LVFX in both aqueous solution and milk medium.This is the first attempt using lanthanide ion-functionalized MSNs to construct a luminescent sensor coupling multiple mechanisms in a single interface to determine LVFX.