In this work, we proposed a novel simple protocol for preparing 1-aminopyrene/graphene (ApG) hybrids for fabricating label-free electrochemical impedance genosensor. Graphene, with the structure of a single-atom-thick sheet of sp2-bonded carbon atoms, was anchored to 1-aminopyrene (1-Ap) with the pyrenyl group via π-stacking interaction. The morphology, conductivity, and interaction of ApG hybrids were characterized by transmission electron microscopy (TEM), cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS), UV-visible (UV-vis) and fluorescence spectra. The amino-substituted oligonucleotide probe was conjugated to 1-Ap by the cross-linker glutaraldehyde. The DNA hybridization reaction of oligonucleotide probe with target DNA was monitored by EIS. Under optimum conditions, the proposed biosensor exhibited high sensitivity and a low detection limit for detecting the complementary oligonucleotide. The target oligonucleotide could be quantified in a wide range of 1.0 × 10−12 to 1.0 × 10−8 M with good linearity (R = 0.9900) and low detection limit of 4.5 × 10−13 M (S/N = 3).
Abstract As a result of their advantages for superparamagnetic properties, good biocompatibility, and high binding capacity, functionalized magnetic materials became widely popular over the past couple of decades, being applied on large scale in various processes of sample preparation for biomedicine. In this work, we perform an in‐depth review on the current progress in the field of magnetic bead separation, discussing in detail the physical basis of this process, various synthesis methods and surface modification strategies. We place special focus of attention as well on the latest applications of magnetic polymer microspheres in cell separation, protein purification, immobilized enzyme, nucleic acid separation, and extraction of bioactive compounds with low molecular weight. Existing problems are highlighted and possible trends of magnetic separation techniques for biomedicine in the future are proposed.
Good faith in paying taxes is an important part of social faith system.Good or bad faith in paying taxes is the result of behavior choice by micro entities,and a basic assumption for studying microeconomic entities is man.Therefore,good faith in paying taxes more reflects the economic essence of good faith.It is the rational behavior adopted by taxpayers after comparing the costs and benefits of good faith and bad faith in paying taxes.Consequently,the key to building an environment for good faith in paying taxes is to satisfy taxpayers' requirement for benefits of good faith in paying taxes,making it a reasonable,legal and rational choice for them.
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