Synthesis Of Fluorescent Carbon Materials And The Application In Biological Thiol Detection

Biosensor has become an important technology in the field of analytical detection.It is widely used in life science,medicine,environmental testing,food engineering and military,which has several advantages,such as high sensitivity,fast detection,easy operation,low cost and continuous dynamic monitoring.Among them,the fluorescent sensors are established by the organic combination of molecular recognition and fluorescence technology.The corresponding fluorescent signal transmission mechanism makes the molecular combinative information into detectable fluorescent signal,realizing real-time detection in situ at the single molecule level.Thiols play an important role in the physiological activities and the concentration closely relate to all kinds of diseases.Therefore,it attracted scientists' attention and interest that the small and medium-sized molecular biological thiols detection research in environmental samples.Around the synthesis of inorganic nanomaterials and phenyl acetylene organic materials,this paper established fluorescent sensors with a variety of different fluorescent signal transmission mechanism.It was successful to accomplish the detection of biological thiols.The concrete research is as follows:1.A fluorescent sensor based on CDs-MnO2 nanocomposites FRET for GSH detection.The carbon dots?CDs?were synthesized by using organosilane as a coordinating solvent,which had a highly luminescent quantum yield.CDs–MnO2 nanocomposites were synthesized with nanoflower-like MnO2 through a facile one-step method.As a result of fluorescence resonance energy transfer?FRET?from CDs to the MnO2,the fluorescence of CDs can be quenched by MnO2.However,when GSH was introduced into the system,the quenched fluorescence could be restored because MnO2 was reduced to Mn2+by GSH,which led to the elimination of FRET.Compared with other electrolytes and biomolecules,we find that the chemical response of the CDs–MnO2 nanocomposites exhibited good selectivity toward GSH.Under the optimal conditions,the proposed immunosensor was successfully performed with a linear range of 0.03–974.1 ?mol.L-1,with a detection limit of 0.015 ?mol.L-1.In addition,the proposed fluorescence sensor has several merits,such as low cost,good selectivity and great biocompatibility.2.A fluorescent sensor based on-C₃N₄ nanosheets-CP IFE for GSH detection.Wesynthesized ultrathin g-C₃N₄ nanosheets by hydrothermal method and a newly designed thiols-specific chromogenic probe?CP?.It is operated on the inner filter effect?IFE?.To construct an efficient IFE system,the CP molecules were adsorbed on the surface of g-C₃N₄ nanosheets via ?-? stacking interaction.When the biothiol introduced the systems,the weak fluorescence would be restored because the “IFE off”.The novel IFE sensor was established to detect GSH as a model target analyte.The IFE sensor has a sensitive response to GSH in a linear range of 0.05 ?M.L-1-1.0 ?M.L-1with a detection limit of 0.01 ?M.L-1.The sensor was successfully applied for the quantitative detection of biothiols in human serum.Additionally,the proposed sensor shows high specificity and sensitivity.3.A fluorescent probe based on P-acid-aldehyde PET for Cys and Hcy detection.The probe is designed and synthesized by incorporating the specific functional group aldehyde group for thiols into a stable ?-conjugated material 4,4'-?2,5-dimethoxy-1,4-phenylene?bis?ethyne-2,1-diyl?dibenzoic acid?P-acid?.The probe fluorescence is quenched through donor photoinduced electron transfer?d-PET?between the fluorophore?P-acid?and the recognition group?aldehyde group?.In the presence of thiols,Cys and Hcy can selectively react with aldehyde group of the probe because the inhibition of d-PET between fluorophore and recognition group.Therefore,a turn-on fluorescent sensor was established for the fluorescence recovery.Under the optimized conditions,the liner range of Cys is 4-95 nM.L-1,with a detection limit 3.0 nM.L-1.In addition,the sensing system exhibits good selectively toward Cys and Hcy.It has been successfully applied for bioimaging of Cys and Hcy in living cells with low cell toxicity.