Aptamer Based SPREETA Sensor for the Detection of Porphyromonas gingivalis G-Protein.

We have developed an aptamer that specifically binds to Porphyromonas gingivalis to reduce the cellular damage caused by P. gingivalis infection and applied it as a biosensor. P. gingivalis is one of the major pathogens causing destructive periodontal disease among the periodontal microorganisms constituting complex biofilms. Porphyromonas gingivalis G-protein (PGP) known to play an important role in the transmission of germs was used as a target protein for the screening of aptamer. The aptamer that has binds to the G-protein of P. gingivalis, was screened and developed through the Systemic Evolution of Ligands by Exponential Energy (SELEX) method. Modified-Western blot analysis was performed with the aptamer which consisted of 38 single-stranded DNA to confirm the selectivity. ELONA (enzyme linked oligonucleotide assay) used to confirm that the aptamer was sensitive to PGP even at low concentration of 1 µg/ml. For the rapid detection of P. gingivalis, we constructed a surface plasmon resonance biosensor with SPREETA using the PGP aptamer. It was confirmed that PGP could be detected as low concentration as at 0.1 pM, which is the minimum concentration of aptamer sensor within 5 min. Based on these results, we have constructed a SPREETA biosensor based on aptamer that can bind to P. gingivalis G-protein. It can be used as an infection diagnosis system to rapidly diagnose and analyze oral diseases caused by P. gingivalis.

Synergistic effect of Fe and BiOCl in enhancing electrocatalytic performance for oxygen evolution reaction.

Fe was added to bismuth oxychloride (BiOCl) to improve its oxygen evolution reaction(OER) catalytic activity. X-ray diffraction (XRD), field emission scanning electron microscopy (FE-SEM), EDS, and X-ray photoelectron spectroscopy (XPS) were used to analyze the material that was produced. Many electrochemical techniques, including linear sweep voltammetry (LSV), Mott Schottky, and electrochemical impedance spectroscopy (EIS), were used to conduct the electrochemical studies of Fe doped BiOCl. Fe doped BiOCl exhibited enhanced catalytic performance compared to pristine BiOCl. The best performance was observed for 0.75 M Fe doped BiOCl sample. It recorded lowest overpotential of 354 mV @ 10 mA cm-2 and Tafel slope of 167 mV dec-1. The synergistic effect of Fe doping from structural, chemical and catalytic perspective has been analyzed and presented.

Rational La-doped hematite as an anode and hydrous cobalt phosphate as a battery-type electrode for a hybrid supercapacitor.

In recent years, modern appliances require high energy density with a burst power supply. Hybrid supercapacitors show high performance based on high energy density without compromising power density and stability over thousands of charge-discharge cycles. In this work, the optimized hybrid electrodes using lanthanum-doped hematite (lanthanum-doped iron oxide) noted as 7.5%La-HMT as a negative electrode and hydrous cobalt phosphate (CoPO) as a battery-type positive electrode have been successfully fabricated via a simple hydrothermal method and a facile co-precipitation method, respectively. The 7.5%La-HMT showed excellent electrochemical performance due to doping of rare-earth La3+ metal ions, resulting in improvised active sites and reduction in the equivalent resistance. The 7.5%La-HMT operated at a high potential window (0 to -1.2 V) with an ultra-high specific capacitance (Sp) of 1226.7 F g-1 at 1 A g-1 with capacitance retention of 89.3% over 1000 cycles. CoPO could be operated at a high working window (0 to 0.45 V) with a specific capacity of 121.7 mA h g-1 at a current density of 2 A g-1 with capacitance retention of 85.4% over 1000 cycles. The configured CoPO//KOH//10%La-HMT aqueous hybrid capacitor device (Aq-HSC) could be operated at a potential window of 1.6 V and delivered a maximum energy density (E.D) of 83.6 W h kg-1 at a power density (P.D) of 3.2 kW kg-1 with Sp of 235.0 F g-1 at 2 A g-1 and 89.0% Sp retention over 5000 cycles. The simplicity of the synthesis methods for CoPO and 7.5%La-HMT along with their superior super-capacitive properties make them suitable for advanced electrical devices and hybrid vehicles.

High-Precision Continuous-Wave Terahertz Spectroscopy Based on a Photomixing Technique for Identifying Pearls.

We present the accurate terahertz spectra of between imitation and cultured pearls using continuous-wave terahertz (CW-THz) spectroscopy. Using Fourier transform infrared (FT-IR) spectroscopy and optical coherence tomography (OCT) measurements, cultured pearls can be distinguished from imitation pearls by observing distinct absorption peaks and discriminative boundaries. The THz absorption spectra up to 0.3 THz obtained from CW-THz spectroscopy show several absorption peaks at specific frequencies with the cultured pearls but no peaks with the imitation pearls, which results from the existence of the nacre polymorph of cultured pearls. Hence, it is expected that the CW-THz system proposed herein will be applicable to fast, nondestructive spectrum analysis including pearl identification.

Facile synthesis of hierarchical mesoporous weirds-like morphological MnO2 thin films on carbon cloth for high performance supercapacitor application.

The mesoporous nanostructured metal oxides have a lot of capabilities to upsurge the energy storing capacity of the supercapacitor. In present work, different nanostructured morphologies of MnO2 have been successfully fabricated on flexible carbon cloth by simple but capable hydrothermal method at different deposition temperatures. The deposition temperature has strong influence on reaction kinetics, which subsequently alters the morphology and electrochemical performance. Among different nanostructured MnO2 thin films, the mesoporous weirds composed thin film obtained at temperature of 453K exhibits excellent physical and electrochemical features for supercapacitor application. The weirds composed MnO2 thin film exhibits specific surface area of 109m2g-1, high specific capacitance of 595Fg-1 with areal capacitance of 4.16Fcm-2 at a scan rate of 5mVs-1 and high specific energy of 56.32Whkg-1. In addition to this, MnO2 weirds attain capacity retention of 87 % over 2000 CV cycles, representing better cycling stability. The enhanced electrochemical performance could be ascribed to direct growth of highly porous MnO2 weirds on carbon cloth which provide more pathways for easy diffusion of electrolyte into the interior of electroactive material. The as-fabricated electrode with improved performance could be ascribed as a potential electrode material for energy storage devices.

Enhanced electrochemical performance of monoclinic WO3 thin film with redox additive aqueous electrolyte.

To achieve the highest electrochemical performance for supercapacitor, it is very essential to find out a suitable pair of an active electrode material and an electrolyte. In the present work, a simple approach is employed to enhance the supercapacitor performance of WO3 thin film. The WO3 thin film is prepared by a simple and cost effective chemical bath deposition method and its electrochemical performance is tested in conventional (H2SO4) and redox additive [H2SO4+hydroquinone (HQ)] electrolytes. Two-fold increment in electrochemical performance for WO3 thin film is observed in redox additive aqueous electrolyte compared to conventional electrolyte. WO3 thin film showed maximum specific capacitance of 725Fg(-1), energy density of 25.18Whkg(-1) at current density of 7mAcm(-2) with better cycling stability in redox electrolyte. This strategy provides the versatile way for designing the high performance energy storage devices.

Detection of Organic Compounds in Water by an Optical Absorbance Method.

This paper proposes an optical method which allows determination of the organic compound concentration in water by measurement of the UV (ultraviolet) absorption at a wavelength of 250 nm~300 nm. The UV absorbance was analyzed by means of a multiple linear regression model for estimation of the total organic carbon contents in water, which showed a close correlation with the UV absorbance, demonstrating a high adjusted coefficient of determination, 0.997. The comparison of the TOC (total organic carbon) concentrations for real samples (tab water, sea, and river) calculated from the UV absorbance spectra, and those measured by a conventional TOC analyzer indicates that the higher the TOC value the better the agreement. This UV absorbance method can be easily configured for real-time monitoring water pollution, and built into a compact system applicable to industry areas.

Protein biosensors based on polymer nanowires, carbon nanotubes and zinc oxide nanorods.

The development of biosensors using electrochemical methods is a promising application in the field of biotechnology. High sensitivity sensors for the bio-detection of proteins have been developed using several kinds of nanomaterials. The performance of the sensors depends on the type of nanostructures with which the biomaterials interact. One dimensional (1-D) structures such as nanowires, nanotubes and nanorods are proven to have high potential for bio-applications. In this paper we review these three different kinds of nanostructures that have attracted much attention at recent times with their great performance as biosensors. Materials such as polymers, carbon and zinc oxide have been widely used for the fabrication of nanostructures because of their enhanced performance in terms of sensitivity, biocompatibility, and ease of preparation. Thus we consider polymer nanowires, carbon nanotubes and zinc oxide nanorods for discussion in this paper. We consider three stages in the development of biosensors: (a) fabrication of biomaterials into nanostructures, (b) alignment of the nanostructures and (c) immobilization of proteins. Two different methods by which the biosensors can be developed at each stage for all the three nanostructures are examined. Finally, we conclude by mentioning some of the major challenges faced by many researchers who seek to fabricate biosensors for real time applications.