Synthesis Of Thermo-sensitive Molecularly Imprinted Fluorescent Sensors Based On Carbon Dots And Their Applications In Detection Of Proteins

Proteins play an important physiological role in organisms,and participate in various chemical and physiological reactions.They are sensitive to ambient environment,and degenerate at unsuited temperatures or pH values.Therefore,it is especially important to find a mild,simple,and rapid detection method of proteins.Molecular imprinting technology is a method of specifically identifying target molecules.It has three unique features:structure predictability,recognition specificity,and application popularity.Therefore,it is widely used in separation,sensing,and drug delivery.Carbon dots,as a type of carbon nanomaterials,have been widely used in optical sensors due to their low toxicity,biocompatibility,and other excellent characteristics.In combination of the high selectivity of molecular imprinting technology and the fluorescence sensitivity of carbon dots,the prepared molecularly imprinted fluorescent sensors stand out from numerous detection methods.Based on the above research background,we designed and prepared molecularly imprinted fluorescent sensors for the detection of proteins with carbon dots as a fluorescent signal and N-isopropylacrylamide as a temperature-sensitive monomer.The work was supported financially by the National Science Foundation?Nos.21573058,21303044,21173070?.The main research contents are as follows:1.N-doped carbon dots?N-CDs?were prepared by the hydrothermal method with polyethylene glycol as carbon source,1-allyl-3-methylimidazolium hexafluorophosphate ionic liquid?[AMIm][PF₆]?as surface passivator,and HF generated by[AMIm][PF₆]decomposition as inductive agent.Under ultraviolet lamp,the aqueous solution of N-CDs showed blue-green fluorescence.A variety of characterizations were performed.These results showed that the obtained N-CDs contained three elements of C,O,and N,and the surface contained-OH,-COOH,-NH₂,and C=C.2.Molecularly imprinted polymer?MIP?for bovine serum albumin?BSA?recognition was prepared by surface imprinting method.N-CDs containing C=C were chosen as the fluorescence signal.Graphene oxide was chosen as the supported material,which can enhance mass transfer.N-Isopropyl acrylamide?NIPAAm?was chosen as the temperature-sensitive monomer,which can control the capture or release of BSA.Fluorescence spectra analysis confirmed the removal and capture of BSA.Furthermore,MIP could be used as fluorescent sensor to detect BSA,with a higher specificity and selectivity.3.Molecularly imprinted polymer?MIP?was prepared by surface imprinting method with CDs/SiO₂as the fluorescence signal,NIPAAm as the temperature-sensitive monomer,and lysozyme as the template molecule.MIP showed thermo-sensitive property to lysozyme.Polymer material was able to swell or shrink to realize the capture or release of the template molecule when the temperature changed.The prepared MIP could be used as fluorescent sensor to detect lysozyme,exhibiting wide detection range,low detection limit,and high selectivity.What's more,fluorescence quenching mechanism was explored.The fluorescence quenching might be ascribed to the transfer of electron between MIP and lysozyme.