Myoglobin immobilization on electrodeposited nanometer-scale nickel oxide particles and direct voltammetry

Myoglobin- and Hydroxyapatite-Doped Carbon Nanofiber-Modified Electrodes for Electrochemistry and Electrocatalysis

In this paper, a hydroxyapatite (HAp)-doped carbon nanofiber (CNF)-modified carbon ionic liquid electrode (CILE) was prepared and used for the investigation on the direct electrochemistry and electrocatalysis of myoglobin (Mb). HAp nanoparticles were mixed within a polyacrylonitrile (PAN) solution, and a HAp@PAN nanofiber was synthesized by electrospinning process, which was further controlled by carbonization at 800 °C for 2 h in a nitrogen atmosphere to get a HAp@CNF nanocomposite. Various techniques were used to check the physicochemical properties of HAp@CNF. Mb was mixed with a HAp@CNF dispersion solution and casted on the surface of CILE to obtain an electrochemical sensing platform. The direct electrochemistry of Mb on the modified electrode was checked when a pair of enhanced redox waves appeared, indicating the direct electron transfer of Mb. HAp@CNF exhibited high conductivity, good biocompatibility, and large surface area, which was beneficial for Mb immobilization. The modified electrode showed excellent electrocatalytic activity toward the reduction of trichloroacetic acid and sodium nitrite, which was further used to establish a new electroanalytical method. Real samples were analyzed by the proposed method with satisfactory results.

Electrochemical nitric oxide biosensor based on amine-modified MoS2/graphene oxide/myoglobin hybrid

Nitric oxide (NO) is one of the most important molecules in living things due to its role as a signaling molecule in influencing pathological and physiological mechanisms including neurotransmission. In this study, the electrochemical biosensor based on the amine-modified molybdenum disulfide nanoparticles (MoS₂), graphene oxide (GO) and myoglobin (Mb) hybrid material (amine-modified MoS₂/GO/Mb hybrid) is developed to achieve the accurate detection of NO with electrochemical signal improvement. For the first time, the synthesis of MoS₂ accompanying the amine-modification of the surface of MoS₂ is done to hybridize with GO efficiently through the short linkage. After the amine-modification of MoS₂, it is enclosed with GO directly (amine-modified MoS₂/GO). Then, Mb which can induce the reduction of NO is immobilized on the amine-modified MoS₂/GO to fabricate the amine-modified MoS₂/GO/Mb hybrid for NO detection. The prepared hybrid shows the signal improved redox properties relative to the result of the electrode prepared without hybrid. Furthermore, upon addition of NO, the electrode prepared with hybrid shows the improved amperometric response compared with that of the electrode without hybrid. This amine-modified MoS₂/GO/Mb hybrid can be used in the development of the biosensor platform accompanying the electrochemical signal improvement and accurate detection of target materials.

S, G. R, D. S, P. R, J. W, Rajendran S, Alwarappan S. Cerium doped nickel-oxide nanostructures for riboflavin biosensing and antibacterial applications

Electrochemical detection of riboflavin and antibacterial activities of Ce doped NiO nanostructures synthesized by the mild temperature wet chemistry approach.

Magnetic Fe3O4 carbon aerogel and ionic liquid composite films as an electrochemical interface for accelerated electrochemistry of glucose oxidase and myoglobin

Synthesized magnetic ferroferric oxide carbon aerogel (Fe₃O₄-CA) was characterized by scanning electron microscope (SEM), atomic force microscopy (AFM) and N₂ adsorption–desorption isotherm measurements.

A fluorescent probe for detecting thiamine using the luminescence intensity of nanoparticles

Determination of molecules and biomolecules using nanoparticles is promising in the development of analytical techniques. Modified Eu-doped Y2O3 nanoparticles (Y2O3:Eu NPs) by captopril have been used as a probe for thiamine (vitamin B1) determination. According to the fluorescence enhancement of modified Eu-doped Y2O3 nanoparticles caused by thiamine, a simple and sensitive method were proposed for its detection. The increase in modified Y2O3:Eu NPs fluorescence signal as a function of thiamine concentration was found to be linear in the concentration range of 0-44 μM. The limit of detection (LOD) of thiamine by this method was 0.144 μM. All the measurements were performed in natural pH, at the room temperature under ambient conditions. Possible interaction mechanism was discussed.

Nano-structured nickel oxide based DNA biosensor for detection of visceral leishmaniasis (Kala-azar)

Sol-gel synthesized nickel oxide (NiO) film deposited onto indium tin oxide (ITO) coated glass plate has been utilized for the development of sensitive and stable DNA biosensor and demonstrated for diagnosis of visceral leishmaniasis also known as Kala-azar. Leishmania specific sensor is developed by immobilizing 23mer DNA sequence (oligonucleotide) identified from 18S rRNA gene sequences from Leishmania donovani. Characterization studies like X-Ray Diffraction and Scanning Electron Microscopy revealed the formation of nano-structured NiO, while immobilization of single strand (ss)-DNA of Leishmania was supported by UV-visible, Fourier Transform Infrared Spectroscopy and Scanning Electron Microscopy techniques. Response studies of ss-DNA/NiO/ITO bioelectrode are carried out using differential pulsed voltammetry in presence of methylene blue redox dye as a redox mediator. A linear response is obtained in the wide concentration range of 2 pg ml(-1) to 2 μg ml(-1) of complementary target genomic DNA (disease DNA) within the variation of 10% for 5 sets of studies. The observed results hold promise not only for diagnosis of Kala-azar patients but also hold enormous potential of the nano-NiO based probe for development of stable and sensitive biosensors.

Iron phosphate nanostructures synthesized by microwave method and their applications in biosensing

A fast, simple microwave heating method has been developed for synthesizing iron phosphate (FePO(4)) nanostructures. The nanostructures were characterized and confirmed by transmission electronic microscopy (TEM), scanning electronic microscopy (SEM), energy-dispersive x-ray spectroscopy (EDS), x-ray photoelectron spectroscopy (XPS), x-ray powder diffraction (XRD), Fourier transform infrared (FT-IR), and UV-vis spectroscopy. The morphology and the size of the nanomaterials are significantly influenced by the concentration of the precursors and the kinds of surfactants. The nanostructures have been employed as an electrode substrate to immobilize myoglobin (Mb) and to facilitate the direct electron transfer (DET) reaction of the protein. After being immobilized on the nanomaterials, Mb can keep its natural structure and undergo effective DET reaction with a pair of well-defined redox peaks at - (330 ± 3.0) mV (pH 6.8) and an apparent electron transfer rate constant of 5.54 s(-1). The Mb-FePO(4)/GC electrode displays good features in the electrocatalytic reduction of H(2)O(2), and thus can be used as a biosensor for detecting substrates with a low detection limit (5 ± 1 µM), a wide linear range (0.01-2.5 mM), a high sensitivity (ca. 85 ± 3 µA mM(-1) cm(-2)), as well as good stability and reproducibility. Therefore, FePO(4) nanomaterials can become a simple and effective biosensing platform for the integration of proteins/enzymes and electrodes, which can provide analytical access to a large group of enzymes for a wide range of bioelectrochemical applications.