The Preparation Of Nanocomposite And Its Application In The Field Of Electrochemical Research

Biosensor is a very active research and engineering technical field. In recentyears, electrochemical biosensors have been shown to be promising sensors for thespecific detection of protein, DNA and small biomolecules in view of its highsensitivity, simplicity, rapid response, and compatibility with miniaturization. Usingnanomaterials for the construction of biosensing devices becomes one of the mostexciting approaches to improve the sensitivity. Thus, the main work of this paper isfocus on the preparation of various nanomaterials, construction of the electrochemicalbiosensors. This work included a review and a research section. In the review section,biosensors, nanomaterials, proteases and so on were introduced.The research section contained the following subunits：1. This work describes a highly sensitive and rapid biosensor fororganophosphorus pesticide based on immobilization of acetylcholinesterase (AChE)on a platinum nanoparticle/polyaniline/grapheme nanocomposites. We successfullyprepared the grapheme, polyaniline/graphene, platinum/nanoparticle/polyanilinegraphene nanocomposites. The biosensor was investigated using square wavevoltammetry to evaluate the suitability of the new electrode for the determination ofdimethoate. Under the optimal conditions, the inhibition of dimethoate wasproportional to its concentration ranging from0.001to0.025and5to21μ g/mL witha detection limit of0.2n g/mL (S/N=3).2. In this work, we developed a novel multiple-label method and multi-signaloutput for simultaneous detection of multiple proteases. The biosensor main consistedof two different peptide substrates and different distinguishable signal nanoprobes.Firstly, biotinylated peptide1(S1) was associated with biotinylated DNA1viabiotin-streptavidin interaction forming DNA1-S1, whereas biotinylated peptide2(S2)was associated with biotinylated DNA2via biotin-streptavidin interaction formingDNA2-S2. Two distinguishable signal nanoprobes (DNA1′-Au NPs-Thi andDNA2′-Au NPs-Fc) were prepared by initial assembling DNA1′and DNA2′on theAu NPs surface, respectively, and then carrying corresponding thionine (Thi) and6-(Ferrocenyl)hexanethiol (Fc). Then, the above peptide substrates (DNA1-S1andDNA2-S2) were immobilized on the gold electrode surface through the chemicaladsorption of the thiol group of the terminal Cys residue, followed by the assembly ofthe distinguishable signal nanoprobes (DNA1′-Au NPs-Thi and DNA2′-Au NPs-Fc) on the peptide-DNA modified electrode surface through DNA hybridization process.Trypsin and chymotrypsin were used as model proteases to demonstrate this proposal.The targets of trypsin and chymotrypsin can specifically recognize and cleavepeptides with different sequences, releasing DNA1′-Au NPs-Thi and DNA2′-AuNPs-Fc from the electrode surface into solution, and thereby reducing the current ofThi and Fc. Using these two different potential signal nanoprobes current reductionintensities upon the addition of targets trypsin and chymotrypsin, the two proteasescan be simultaneously quantitatively determined. More importantly, this strategy canbe extended easily by designing various proteases-specific peptide substrates andutilizing corresponding electrochemical detectable elements (not limited to electronicmediators) for simultaneous, efficient and accurate multiplex protease assay invarious biosystems.