Artificial-enzyme gel membrane-based biosurveillance sensor with high reproducibility and long-term storage stability

We propose that the most sophisticated strategy for primary biosurveillance is to exploit structural commonality through the detection of biologically relevant phosphoric substances. A novel assay, an artificial-enzyme membrane was designed and synthesized for sensor fabrication. This artificial-enzyme catalyzes the hydrolysis of the diphosphoric acid anhydride structure. This structure-selective, albeit not molecule-selective, catalytic hydrolysis was successfully coupled with amperometric detection. Since the catalytic reaction produces a dephosphorylation product (PO43−), it can be reduced by an electrode potential of −250 mV vs. Ag/AgCl. Owing to the structural selectivity of the artificial-enzyme membrane, the sensor can detect biological phosphoric substances comprehensively that have the diphosphoric acid anhydride structure. The sensor successfully determined various biological phosphoric substances at concentrations in the micromolar (µM) to millimolar (mM) range, and it showed good functional stability and reproducibility in terms of sensor responses. This sensor was used to detect Escherichia coli lysed by heat treatment, and the response increased with increasing bacterial numbers. This unique technique for analyzing molecular commonality can be applied to the surveillance of biocontaminants, e.g. microorganisms, spores and viruses. Artificial-enzyme-based detection is a novel strategy for practical biosurveillance in the front line

Post-Synapse Model Cell for Synaptic Glutamate Receptor (GluR)-Based Biosensing: Strategy and Engineering to Maximize Ligand-Gated Ion-Flux Achieving High Signal-to-Noise Ratio

Peer reviewe

Photoelectrochemical reduction of CO2 using a TiO2 photoanode and a gas diffusion electrode modified with a metal phthalocyanine catalyst

The mass transport limitations encountered in classical H-cells for electrochemical CO2 reduction reaction (CO2RR) have spurred research in gas diffusion electrode (GDE) systems. However, current reports on CO2RR required large biases (anode potential vs. cathode potential > -2.0 V) for high current efficiencies. In this work, we combined a TiO2 photoanode and a GDE modified with a Co, Ni or Sn metal phthalocyanine (MPc) catalyst to reduce the external bias requirement for CO2RR. We found the Faradaic efficiencies and the selectivity of the photoelectrolysis products were influenced by (i) the metal cation (Ni, Co or Sn) coordinated to the phthalocyanine, (ii) the electrolyte temperature and concentration and (iii) the magnitude of the applied bias. In addition, analyzes of the voltage distributions between the TiO2 photoanode and the MPc-GDE revealed the current efficiency of the TiO2/MPc-GDE cell was limited predominantly by a high ohmic polarization loss at the TiO2 photoanode due to an excessive thickness of the TiO2 layer. The cathodic process at the MPc-GDE was governed by the activation energy of the electrode. The thickness of the TiO2 photoanode was subsequently optimized for higher current efficiency. The highest Faradaic efficiency for PEC CO2RR was obtained when a NiPc catalyst was utilized as the CO2RR catalyst and the optimum cell conditions were as follows: (i) a GDE electrolyte temperature of 1 M aq. Na2SO4 electrolyte solution and (iii) a TiO2 oxidation time of 3 h. Using these optimized cell conditions and under UV illumination, the as-prepared TiO2/NiPc-GDE cell shows a notably high CO2RR Faradaic efficiency and selectivity for CO (at 98%) and at a lowest reported cell bias of 0.8 V (anode potential vs cathode potential). This work provides an improved understanding of the cell designs of a vapor-fed CO2RR reactor based on a TiO2/MPc-GDE photoelectrochemical system

Ordered nano-structure of a stamped self-organized protein layer on a HOPG surface using a HFB carrier

金沢大学理工研究域バイオＡＦＭ先端研究センターA groundbreaking method for ordered molecular layer preparation on a solid surface employing the drop-stamp method has been developed by us taking advantage of the characteristics of the HFB molecule as a self-organizer/adsorption carrier. It is a smart method which can be used to prepare a self-organized protein layer on a solid surface without unspecific adsorption or defects. In our previous report, we clarified the self-organizing nature of HFB-tagged protein molecules on a surface of a solution droplet. In this report, a protein layer was prepared on a HOPG surface by using the drop-stamp method with a maltose binding protein (MBP)-tagged HFBII molecule. The structure of the stamped protein layer was investigated using frequency modulation atomic force microscopy (FM-AFM) in a liquid condition. The FM-AFM images show that the drop-stamp method can prepare an ordered protein layer on a solid surface smartly. The drop-stamp method using a HFB carrier is a practical method which can be used to prepare an ordered protein layer on a solid substrate surface without unspecific adsorption defects. © 2011 Elsevier B.V

Gold Nanoparticles Functionalized with Peptides for Specific Affinity Aggregation Assays of Estrogen Receptors and Their Agonists

Nuclear receptors regulate the transcription of genes and various functions such as development, differentiation, homeostasis, and behavior by formation of complexes with ligand and co-activator. Recent findings have shown that agonists of a ligand may have a toxic effect on cellular/tissular function through improper activation of nuclear receptors. In this study, a simple assay system of hetero-complexes of three different molecules (estrogen receptor, ligand, and co-activator peptide) has been developed. This assay system employs functionalized gold nanoparticles (GNPs: 15 nm in diameter). The surfaces of the GNPs were modified by a 12- or 20-amino-acid peptide that contains the sequence of co-activator for activating nuclear receptor by an agonist ligand. Owing to the affinity of the peptide, the functionalized GNPs aggregate faster when the nuclear receptor and the agonist ligand are also present. The aggregation of GNPs can be identified by shifts in adsorption spectrum, which give information about the specificity of agonist ligands. Similarly, this spectrum shift can measure concentration of known agonist ligand. This simple agonist screening will be employed as high through-put analysis (HTA) in the discovery of drugs that act through nuclear receptors

Ordered nano-structure of a stamped self-organized protein layer on a HOPG surface using a HFB carrier

A groundbreaking method for ordered molecular layer preparation on a solid surface employing the drop-stamp method has been developed by us taking advantage of the characteristics of the HFB molecule as a self-organizer/adsorption carrier. It is a smart method which can be used to prepare a self-organized protein layer on a solid surface without unspecific adsorption or defects. In our previous report, we clarified the self-organizing nature of HFB-tagged protein molecules on a surface of a solution droplet. In this report, a protein layer was prepared on a HOPG surface by using the drop-stamp method with a maltose binding protein (MBP)-tagged HFBII molecule. The structure of the stamped protein layer was investigated using frequency modulation atomic force microscopy (FM-AFM) in a liquid condition. The FM-AFM images show that the drop-stamp method can prepare an ordered protein layer on a solid surface smartly. The drop-stamp method using a HFB carrier is a practical method which can be used to prepare an ordered protein layer on a solid substrate surface without unspecific adsorption defects

Boost protein expression through co-expression of LEA-like peptide in Escherichia coli.

The boost protein expression has been done successfully by simple co-expression with a late embryogenesis abundant (LEA)-like peptide in Escherichia coli. Frequently, overexpression of a recombinant protein fails to provide an adequate yield. In the study, we developed a simple and efficient system for overexpressing transgenic proteins in bacteria by co-expression with an LEA-like peptide. The design of this peptide was based on part of the primary structure of an LEA protein that is known hydrophilic protein to suppress aggregation of other protein molecules. In our system, the expression of the target protein was increased remarkably by co-expression with an LEA-like peptide consisting of only 11 amino acid residues. This could provide a practical method for producing recombinant proteins efficiently