Three Kinds Of Novel Electrobiosensors Based On Nanomaterials And Ionic Liquids

Electrochemistry biosensor is a kind of analytical devices with many advantages such as convenient, simply, cheap and fast, which employ biomaterials (such as biomolecules, cells, tissue and organs) as the identification module, electrodes as the transducer and electrochemistry responses (such as current, impedance and capacitance) as the detection signal. In this paper, three kinds of novel biosensors combined the nanomaterials and ionic liquids were fabricated. Direct electrochemistry and electrocatalysis of myoglobin (Mb) and hemoglobin (Hb) was studied on two kinds of metal nanoparticles modified carbon ionic liquid electrode (CILE). Moreover a novel electrochemiscal DNA biosensor was prepared based on V₂O₅ nanobelts-multiwalled carbon nanotubes (MWCNTs)-chitosan (CTS) composite modified CILE. The main contributions are summrized as below:I. The electrochemical deposition of Co nanoparticles on CILE was described and further used as the platform to construct a Mb electrochemical biosensor. CILE was prepared by mixing a certain ratio of carbon powder, 1-ethyl-3-methylimidazolium tetrafluoroborate (EMIMBF4) and liquid paraffin together. A layer of Co nanoparticles was deposited on the surface of CILE with the average diameter of 300 nm after the cyclic voltammetic scan in the CoCl2 solution. Mb molecules were further cast on the surface of Co/CILE and immobilized with Nafion film and the formed Co/CILE was used as a new basal electrode for the investigation on the direct electrochemistry of protein. The Mb electrochemical biosensor showed good electrocatalytic activity to the reduction of hydrogen peroxide (H₂O₂) and trichloroacetic acid (TCA).II. A carbon ionic liquid electrode (CILE) was fabricated by using ionic liquid 1-ethyl-3-methylimidazolium ethylsulfate (EMIMEtOSO₃) as modifier and further gold nanoparticles were in situ electrodeposited on the surface of CILE. The fabricated Au/CILE was used as a new platform for the immobilization of Hb with the help of a Nafion film. Electrochemical experimental results indicated that direct electron transfer of Hb was realized on the surface of Au/CILE with a pair of well-defined quasi-reversible redox peaks appeared. The fabricated Nafion/Hb/Au/CILE showed excellent electrocatalytic activity to the reduction of trichloroacetic acid (TCA). The proposed electrode showed good stability and reproducibility, and it had the potential application as a new third-generation electrochemical biosensor.III. A new electrochemical DNA biosensor was fabricated by using a V₂O₅ nanobelts (nano-V₂O₅), multiwalled carbon nanotubes (MWCNTs) and chitosan (CTS) nanocomposite materials modified carbon ionic liquid electrode (CILE) as the working electrode. The CILE was prepared by using N-hexylpyridinium hexafluorophosphate (HPPF6) as the binder with the graphite powder. The CTS-V₂O₅-MWCNTs/CILE was used as the basal electrode for the immobilization of the single-stranded DNA (ssDNA) probe. After the hybridization with the target ssDNA sequence, the electrochemical indicator of methylene blue (MB) was used to monitor the hybridization reaction. Experimental data indicated that the synergistic effect of nano-V₂O₅ and MWCNTs increased the amounts of ssDNA adsorbed on the electrode surface and resulted in the corresponding increase of the electrochemical responses. This DNA biosensor combined the advantages such as the biocompatibility of V₂O₅ nanobelt, the excellent electron transfer ability of MWCNTs, the good film-forming ability of CTS and the high conductivity of CILE. The DNA biosensor showed good stability and discrimination ability to the one-base and three-base mismatched ssDNA sequence. The loop-mediated isothermal amplification (LAMP) product of Yersinia enterocolitica gene sequence in pork meat was detected by the proposed method with satisfactory result, suggesting that the CTS-V₂O₅-MWCNTs/CILE had the potential for the sensitive detection of specific gene sequence.