At present, there is an urgent need to design sensitive substrates for the Raman analysis system to detect potential substances that have major ramifications for health care and the ecological environment. In this work, CoFe2O4/Ag nanostructures with two different morphologies were successfully synthesized as surface-enhanced Raman scattering (SERS) substrates. The as-prepared strawberry-like CoFe2O4@SiO2@Ag and snowman-like CoFe2O4-Ag Janus not only displayed high sensitivity due to the surface plasma resonance (SPR) of Ag nanoparticles and special micro-nano structure but also showed good stability, which was determined by Raman measurement and enhancement factor calculation. Moreover, excellent magnetic response ensured that the composites could be separated rapidly and reused effectively. It was demonstrated that the as-synthesized CoFe2O4@SiO2@Ag and CoFe2O4-Ag Janus composites had great potential as separable, reusable, and active SERS substrates.
Mercuric ion (Hg 2+ ) is one toxic metal ion existed in aquatic ecosystems which would seriously damage human central nervous system and other organs. So developing an approach to sensitively detect Hg 2+ in our living environment is urgent and important. In this work, a novel surface enhancement Raman spectrum(SERS) sensor is fabricated for high selective and ultrasensitive detection of Hg 2+ in aqueous solution, based on a stable thymine-Hg 2+ -thymine (T-Hg 2+ -T) structure and the π - π interaction between single-stranded DNA (ssDNA) and single walled carbon nanotubes (SWCNTs). Herein, SWCNTs act as Raman labels to produce characteristic Raman peaks which can be a beacon to quantitative detect Hg 2+ . In the presence of Hg 2+ , the ssDNA can capture Hg 2+ forming T-Hg 2+ -T structure, which makes SWCNTs leave the hot spots of the SERS-based biosensor. With this design, the Raman intensity of SWCNTs decreased with the increasing concentration of Hg 2+ . At the same time, CoFe 2 O 4 @Ag as active SERS substrates can effectively enhance sensitivity and uniformity of the biosensor through aggregation by magnet. Under optimal conditions, this proposed biosensor can detect Hg 2+ at a range from 1 pM to 100 nM with a detection limit of 0.84 pM. With the advantages of good sensitivity, selectivity, simplicity and rapidity, the biosensor is potentially suitable for monitoring of Hg 2+ in environmental applications.
Xiao Wang,Mei Wu,Chulei Zhao,Xiaochen Liao,Mengmeng Zhang,Lisha Mei,XiuWen Qiao,Chenglin Hong
Using Ag-CoFe 2 O 4 -GO nanocomposite as biosensor interface, a novel unlabelled electrochemical immunosensor was designed to detect tumour marker carcinoembryonic antigen. Here, Ag-CoFe2O4-GO was synthesized by one-pot method as an immunological probe. They have the following advantages: (1) Silver nanoparticles have a strong redox capacity under applied voltage and good biocompatibility, so they can bind more antibodies; (2) GO has a large specific surface area, which can load more Ag NPs and CoFe 2 O 4 nanoparticles, and has excellent conductivity; (3) CoFe 2 O 4 is widely favoured by researchers due to its advantages such as low production cost and simple preparation process, The prepared Ag-CoFe 2 O 4 -GO nanocomposite can amplify the electrochemical signal; (4) The presence of GO can effectively prevent the agglomeration of Ag NPs nanoparticles and CoFe 2 O 4 nanoparticles, promote the formation of electron transfer network, and contribute to the electron transfer of sensors. Under optimal condition, the current signal and the concentration of carcinoembryonic antigen were linear in the range of 1 pg mL < sp > −1 < /sp > ∼ 80 ng mL < sp > −1 < /sp , > and the detection limit was 0.3 pg mL < sp > −1 < /sp > (S/N = 3). Under certain conditions, the manufactured immunosensor has good reproducibility, selectivity and excellent stability. Thus it has certain clinical value for the detection of carcinoembryonic antigen.
危险品化学品经营许可证（带存储）