| Electrochemiluminescence(ECL)analysis is based on the light signal generated by the excitation of electrodes;it is,in fact,a method combining electrochemistry and chemiluminescence.ECL analysis has been widely used in environmental,biological,medical and other analysis fields due to its excellent performance such as low background noise,high sensitivity,and fast and convenient detection.Luminescent materials are the cores of ECL technology which determine the sensitivity and selectivity of analytical methods.Traditional luminescent materials include luminol and Ru(bpy)32+and their various derivatives.In recent years,with the continuous research and development of new materials,semiconductor quantum dots with excellent optoelectronic properties have also attracted widespread attention.Many of these metal sulfide quantum dots exhibit good ECL performance,but most of them contain toxic metals,such as Cd,Pb,etc.,which limit their applications.Compared with metal quantum dots,carbon dots have been favored by various parties due to their low toxicity and low harm,less harmful to the environment and simple preparation.At present,ECL research on carbon dots mainly focuses on:1.Selecting appropriate carbon sources and methods to synthesize carbon dots with good ECL performance;2.Modifying carbon dots by doping or functional group modification to improve their luminous efficiency and selective response.Boronic acid is a specially structured acid that can covalently interact with cis-1,2-or 1,3-diol to form five-or six-membered cyclic esters.The process is reversible.This effect is highly dependent on p H and is generally carried out under alkaline conditions.This effect is called boric acid affinity.With boronic acid affinity as the main driving force in the molecular recognition process,the constructed sensor has high selectivity and good stability.Combining some advanced materials and technologies(such as nanomaterials,molecular imprinting technology,ECL,etc.)to design new ECL sensors for target molecules has unique advantages and broad prospects.In this paper,We selected phenylboronic acid as the precursor to synthesize boronic acid-functionalized carbon dots(B-CDs)by a one-step hydrothermal method.Three different ECL sensors were constructed using B-CDs as a luminescent material,which were successfully applied to the detection of related substances.The specific work is as follows:1.Synthesis and electrochemiluminescence properties of the boronic acid functionalized carbon dots(B-CDs)Using phenylboronic acid as the only precursor,the carbon dots with boric acid structure on the surface were synthesized by one-step hydrothermal method,and the synthesis conditions were optimized with the ECL performance as the index.The morphology,surface composition and spectral characteristics of the B-CDs were detailedly analyzed by transmission electron microscopy(TEM),X-ray photoelectron spectroscopy(XPS),UV-vis spectra(UV-vis),Fluorescence spectra(FL),and Fourier transform infrared spectroscopy(FT-IR),and its ability to recognize cis-diols were tested.The experimental results showed that the synthesized B-CDs had a good ECL performance and showed strong selective recognition for cis-diols substances.2.An ECL sensor based on boronic acid-functionalized carbon dots(B-CDs)for sensitive detection of glucoseGlucose is a typical cis-diol substances with two pairs of cis-diols in its molecular structure,which can undergo esterification with boronic acid.In this work,we immobilized B-CDs on the electrode by the good film-forming properties of chitosan to construct an ECL sensor.The sensitive detection of glucose was realized by the interaction of B-CDs on the sensor surface with glucose.The experimental results showed that the ECL sensor exhibited a good linear response to the glucose concentration in the range of 1.0×10-10?1.0×10-6mol·L-1,and the detection limit was2.3×10-11mol·L-1(S/N=3).3.Molecularly imprinted electroluminescence(MIP-ECL)sensor with a dual recognition effect for detection of dopamineDopamine(DA)is an important neurotransmitter that affects various motivations and behaviors in animals.The precise determination of DA has very important clinical significance in biological systems.The DA molecule contains a cis-diol structure,which can react with boronic acid on the surface of B-CDs,thereby realizing the detection of DA.However,there are a variety of cis-diols substances in biological samples,such as glucose,epinephrine,etc.,which all react with B-CDs and interfere with the detection of DA.In order to solve this problem,we introduced a molecularly imprinted polymeric(MIP)membrane with specific recognition of DA when constructing the sensor,and used the MIP and boronic acid structure to double-recognize DA to achieve highly selective detection of DA.The experimental results showed that the MIP-ECL sensor exhibited a good linear response with the DA concentration(1.0×10-9?1.0×10-5mol·L-1),and the detection limit was 2.1×10-10mol·L-1(S/N=3).4.An ECL turn on sensor for sensitive detection of fluoride ionsThe recognition of cis-diol by B-CDs is based on the formation of cyclic ester between boronic acid and cis-diol,and the detection of cis-diol substances is realized due to the change of ECL signal of B-CDs caused by the formation of cyclic ester.We know that there is a strong interaction between fluorine(F)and boron(B).When F-exists in the solution,it will compete for B in the cyclic ester and the ester ring structure will be destroyed.Taking advantage of this feature,we design a method to detect F-with an ECL turn on sensor.First,B-CDs were loaded on the electrode,and then inserted into the solution containing DA,the ECL signal was quenched due to the interaction between DA and B-CDs on the electrode surface,and then the electrode was inserted into the solution containing F-,it would competing for B in the cyclic ester unraveled the ester ring structure and released DA,and the ECL signal was recovered.The degree of recovery showed a linear response to the concentration of F-.The response range is 1.0×10-10?1.0×10-7mol·L-1,and the detection limit is2.1×10-11mol·L-1(S/N=3). |
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