| Electrochemiluminescence(ECL)refers to a light emission process in which species generated at the electrode surface undergo exergonic electron transfer reaction to form excited states that emit light.In a sense,ECL is the ideal combination of electrochemical and spectroscopic methods.Therefore,ECL not only holds the sensitivity and wide dynamic range inherited from conventional chemiluminescence(CL)but also exhibits several advantages of electrochemical methods including simplicity,stability,and facility.On the other hand,as a light emission technique,ECL possesses unique superiorities over other light emission methods,such as photoluminescence(PL)and CL.Therefore,ECL has now become a powerful analytical technique and been widely used in a large number of environments,ranging from fundamental studies to practical applications for sensing trace amounts of target molecules.Chemiluminescence,as a powerful analytical technique,possessing the advantages of high sensitivity,wide detection range,low equipment requirements and low background interference,has been widely used in various fields including biotechnology,pharmacology,molecular biology and environmental chemistry.Nano-materials with large surface area,good biocompatibility,and other characteristics have been wildly used in the field of biosensors for sensitive detection.A series of sensitive electrochemical luminescence or chemiluminescence biosensors were constructed using nanometer materials as luminescent materials,or their composite materials to construct sensitive interfaces and signal amplification probes.The main contents of this think are as follows:(1)A CdTe/CdS QDs(with a CdTe core and a CdS shell)amplified electrogenerated chemiluminescence(ECL)of nitrogen functional graphene quantum dots(NGQDs)platform is reported.The utilization of CdTe/CdS QDs could facilitate the production of NGQDs radical,and then,a high yield of NGQDs*was formed due to the interaction of NGQDs radical with O2·-,leading to a?21-fold ECL enhancement.This ECL enhancing system does not require the addition of coreactant and modification of electrode which is carried out in homogeneous solution.Benefiting from the remarkable ECL enhancement effect,a feasible and sensitive ECL sensor was constructed for ascorbic acid(AA)quantification.The proposed method features a detection limit of 70 nM with a linear calibration range from 100 nM to 100?M,and exhibits good stability,practicability,and acceptable fabrication reproducibility,showing promising application in real sample.(2)We presented a novel single luminophor dual-potential ECL system for the fabrication of a convenient ratiometric sensor for Co2+ ion detection.During the cyclic potential scanning,dissolved oxygen changes to O2·-and HO2-which participate in the anodic and cathodic ECL generating process of NGQDs.Co2+ ion is demonstrated to play the catalytic action of the intermediate steps of anodic ECL reactions to amplify the anodic intensity,and decrease the cathodic ECL intensity due to the inhabitation and quenching effects on the excited state of the luminophor.Hence the target Co2+ ion is quantified by the ratio of ECL intensities at two excitation potentials.The constructed ratiometric dual-potential ECL system shows excellent selectivity against common metal ions.The proposed ratiometric ECL sensor was used to detect trace Co2+ ion in real water.The proposed Co2+ ion modulated ECL strategy of NGQDs without extra oxidizing coreactant(such as H2O2,S2O82-)addition would pave a way for Co2+ related biological sensor construction.As a single luminophor,NGQDs possessing multiple-ECL signals is straightforward without labeling,providing more reliable signals in sensing than traditional single ECL signal dependent strategies.Utilizing the dual-potential ECL sensor,the unavoidable uncertainty of single ECL signal could be largely avoided,making the sensing more credible in principle.(3)Since the two ends of coenzyme A(CoA)are free thiol group and adenine,a kind of CoA-Ag complex is synthesized with the interaction of thiol group and Ag+and holds the properties similar to the RNA structure because of the adenine structure at the other end of the coenzyme A.The prepared CoA-Ag complex can easily and effectively bind with GO through its adenine side group caused by ?-? stacking interaction.Moreover,CoA-Ag complex adsorbed on GO modified electrode surface possesses high electrochemical catalytic activity toward H2O2 reduction and significantly enhance cathodic ECL signal of CdTe@CdS QDs.In addition,the degree of ECL enhancement is related to the amount of CoA-Ag complex.Hence,an ECL sensing sensor for CoA detection was constructed based on the relationship between the Co A substrate concentration and the degree of enhancement of ECL signal.HAT p300 catalyzes the transfer of an acetyl group from Ac-CoA to the lysine residue of substrate peptide producing CoA and s-N-acetyl group lysine residue.CoA-Ag complex was formed in the aid of Ag+ and coenzyme A produced from acetyl-CoA catalytic reactions,and able to enhance ELC signal of CdTe@CdS QDs.The activity of p300 HAT was quantitatively measured by monitoring Co A generation during the acetylation.An ECL sensor platform for acetyltransferase p300 activity measuring and inhibitor screening was fabricated.(4)NGQDs was fabricated and demonstrated to generate CL under the direct effects of H2O2.In addition,Cu2+ ion can enlarge the CL intensity of NGQDs 214 times for its catalysis on Fenton-like reaction of H2O2 decomposition,and display unique specificity against other metal ions.Afterward,the mechanisms of Cu2+ ion enhanced chemiluminescence of NGQDs/H2O2 system are discussed in details.Furthermore,the developed Cu2+/NGQDs/H2O2 system emitting persistent light was applied for visual imaging sensing.Finally,an imaging sensing method based on Cu2+/NGQDs/H2O2 CL system is developed for AA detection and applied in real fruit sample.The CL imaging method has high stability and proper sensitivity providing a convenient and visual tool for AA determination. |
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