Highly-sensitive electrochemiluminescence biosensor for detection of inosine monophosphate in meat based on graphdiyne/AuNPs/luminol nanocomposites

Inosine monophosphate(IMP),as a critical umami substance,is one of the most important indicators for evaluating the quality of meat products.Here,a sensitive electrochemiluminescence(ECL)biosensor based on graphdiyne(GDY)/AuNPs/luminol nanocomposites was constructed to detect IMP.The GDY/AuNPs/luminol nanocomposites were synthesized by using simple one-pot method.GDY utilized its 2D framework to disperse and fix gold nanoparticles,which inhibited the agglomeration of gold nanoparticles and greatly improved its stability and catalytic properties.Importantly,GDY/AuNPs/luminol nanocomposites showed excellent catalytic ability and superior ECL activity towards luminol-H_(2)O_(2) systems due to the synergistic effect of GDY and AuNPs.Under optimal conditions,the prepared biosensor exhibited a wide linear range from 0.01 g/L to 20 g/L,a satisfactory limit detection of 0.0013 g/L,as well as an excellent specificity.Moreover,we carried out the precise analysis of IMP in actual meat samples with acceptable results compared to the liquid chromatography.We believe that this work could offer an efficient ECL platform for accurate and reliable report of IMP levels,which is significant for maintaining food quality and safety.

Electrochemical Biosensor for Multiple Methylation-Locus Analysis Based on DNA-AuNPs and Bienzymatic Dual Signal Amplifications

DNA methylation plays a significant role in various biological events, and its precise determination is vital for the prognosis and treatment of cancer. Here, we proposed an ultrasensitive electrochemical biosensor for the quantitative analysis of multiple methylation-locus in DNA sequence via DNA anchoring the gold nanoparticles (DNA-AuNPs) and bienzyme dual signal amplifications. After the target DNA captured by the DNA-AuNPs of the biosensor, the methyl-CpG binding protein MeCP2 could specifically conjugate to the methylation-loci in the double-stranded DNA. Successively, the glucose oxidase (GOD) and horseradish (HRP) co-labeled antibody captured the His tagged MeCP2, which leads to a cascade enzymatic catalysis of the substrates to yield a detectable electrochemical signal. Both the two strategies, including the high content of DNA-AuNPs and the associated catalysis of bienzyme, dramatically enhanced the sensitivity of the biosensor. The response current elevated with the increasing numbers of methylation-locus, thus the multiple methylated DNA was identified by detecting the corresponding current signals. This method could detect the methylated target as low as 0.1 fM, and showed a wide linear range from 10 - 15 M to 10 - 7 M. Besides, the long-term stability and repeatability of the biosensor were also validated. The prepared electrochemical immunosensor exhibits ultrasensitivity through the bienzyme labeling process, which can be applied for the detection of DNA methylation with low concentration.

A novel amperometric biosensor based on gold nanoparticles-mesoporous silica composite for biosensing glucose

We report a novel bienzyme biosensor based on the assembly of the glucose oxidase (GOD) and horseradish peroxidase (HRP) onto the gold nanoparticles encapsulated mesoporous silica SBA-15 composite (AuNPs-SBA-15). Electrochemical behavior of the bienzyme bioconjugates biosensor is studied by cyclic voltammetry and electrochemical impedance spectroscopy. The results indicate that the presence of mesoporous AuNPs-SBA-15 greatly enhanced the protein loadings, accelerated interfacial electron transfer of HRP and the electroconducting surface, resulting in the realization of direct electrochemistry of HRP. Owing to the electrocatalytic effect of AuNPs-SBA-15 composite, the biosensor exhibits a sensitive response to H2O2 generated from enzymatic reactions. Thus the bienzyme biosensor could be used for the detection of glucose without the addition of any mediator. The detection limit of glucose was 0.5 μM with a linear range from 1 to 48 μM.