Brewster Angle Microscopic Study of Mixed Lipid-Protein Monolayer at the Air-Water Interface and Its Application In Biosensing (original) (raw)
Related papers
Nano Convergence
In this research, we developed electrochemical biosensor which was composed of hemoglobin (Hb)-DNA conjugate on nanoporous gold thin film (NPGF) for hydrogen peroxide (H 2 O 2) detection. For the first time, Hb and DNA was conjugated as a sensing platform for uniform orientation of Hb on electrode. The newly developed Hb-DNA conjugate was designed to prevent Hb from aggregation on electrode. DNA hybridization of Hb-DNA conjugate and complementary DNA (cDNA) on NPGF electrode induced uniformly assembled biosensor. Furthermore, NPGF electrode fabrication method was introduced to the increment of the surface area. To confirm the conjugation of Hb-DNA conjugate, sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE) and ultraviolet-visible spectroscopy (UV-VIS) were used. Formation of the NPGF electrode was verified by scanning electron microscope (SEM). Atomic force microscopy (AFM) was operated for the confirmation of Hb-DNA immobilization on electrode. The electrochemical property of fabricated electrode was investigated by cyclic voltammetry (CV). Also, H 2 O 2 sensing performance of fabricated electrode was investigated by amperometric it curve technique. This sensor showed a wide linear range from 0.00025 to 5.00 mM and a correlation coefficient of R 2 = 0.9986. The detection limit was 250 nM. Proposed biosensor can be utilized as a sensing platform for development of biosensor.
Thin Solid Films, 2012
In order to develop a sensitive label-free impedimetric immunosensor for a cardiac marker, heart-type fatty acid-binding protein (hFABP) detection, electrochemical impedance spectroscopy was used to monitor each step of the gold surface functionalization. The gold electrode was functionalized with homogeneous self-assembled monolayer (hSAM) by using 11 mercaptoundecanoic acid (MUA), versus mixed SAM (mSAM) for which a mixture of MUA and 3 mercaptopropanol was used. A comparative study regarding, both the insulating properties of the hSAM and mSAM and the evaluation of the effect of steric hindrance of the hSAM in the anti hFABP antibody binding efficiency, was performed with cyclic voltammetry and impedance spectroscopy. Also, in order to optimize the surface functionalization, the SAMs (self-assembled monolayers) forming was evaluated for different immobilization times of the alkanethiols. The modified gold surface was activated with 1-Ethyl-3-[3-dimethylaminopropyl] carbodiimide hydrochloride and N-hydroxysuccinimide, followed by the covalent immobilization of anti hFABP antibody. Bovine serum albumin was used to block the non-specific sites. A good correlation between the impedance change and the range of hFABP antigen concentration of 98 pg.ml −1-100 ng.ml −1 was observed for the mSAM modified gold electrode, with detection limit of 117 pg.ml −1 .
The effect of lipid bilayer manipulation on the response of the glucose oxidase-liposome electrode
Biosensors and Bioelectronics, 1997
The use of lipids in the construction of membranes for biosensors has been well documented. They have been used on electrode surfaces to reduce interferences from electroactive species such as ascorbate, while lipid bilayers have been used to immobilize enzymes. Recently, liposomes have been used to encapsulate glucose oxidase and these iiposomes have been immobilized on a Rank electrode polarized to measure the production of hydrogen peroxide. In this case liposomes were used as a diffusion limiting membrane to reduce the exposure of the oxidase to glucose and therefore increase the linear range of the enzyme to a level of clinical use (0--40 mM). The original method of liposome production (reverse phase evaporation) was altered to a method of vesicle extrusion to provide more reproducible results. Liposomal electrodes from this system showed an extended K m of over 100 mM and a slow response time of 5 min. This paper describes research undertaken on the manipulation of the lipid bilayer of the iiposome. By varying the composition of the lipids in the bilayer the response size, time and apparent Km can all be altered.
An amperometric H2O2biosensor based on hemoglobin nanoparticles immobilized onto a gold electrode
Bioscience reports, 2017
The nanoparticles (NPs) of hemoglobin (Hb) were prepared by desolvation method and characterized by transmission electron microscopy (TEM), ultraviolet (UV) spectroscopy and Fourier-transform infrared spectroscopy (FTIR). An amperometric H2O2 biosensor was constructed by immobilizing HbNPs covalently onto a polycrystalline Au electrode (AuE). HbNPs/AuE was characterized by scanning electron microscopy (SEM), cyclic voltammetry (CV) and electrochemical impedance spectra (EIS) before and after immobilization of HbNPs. The HbNPs/Au electrode showed optimum response within 2.5s at pH 6.5 in 0.1M sodium phosphate buffer containing 100μM H2O2 and 30⁰C, when operated at -0.2V against Ag/AgCl. The HbNPs/AuE exhibited Vmax of 5.161±0.1 μA cm(-2) with Michaelis-Menten constant (Km) of 0.1±0.01mM. The biosensor showed lower detection limit (1.0μM), high sensitivity (129±0.25μA cm(-2) mM(-1)) and wider linear range (1.0-1200μM) for H2O2 as compared to earlier biosensors. The analytical recoveri...
Hydrogen Peroxide-Sensitive Electrode Based on Supported Bilayer Lipid Membrane
1993
Electrodes are described based on horseradish perosidase (HRP) modified platinized carbon particles which are capable of reducing hydrogen peroxide at 0.0 V (vs. SCE). The HRP was covalently attached to the surface of the carbon particles via cyanuric chloride. Energ-dispersive X-ray analysis confirmed the presence of cyanuric chloride on the surface of the carbon. Electrochemical studies on these electrodes indicated that they were stable for extended periods and that she bound HRP was capable of mediating the electrocatalytic reduction of hydrogen peroxide.
Enzyme-immobilized Langmuir-Blodgett film for a biosensor
Thin Solid Films, 1988
A lipid-protein monolayer for a biosensor was prepared utilizing a Langmuir-Blodgett technique. The enzyme glucose oxidase was used as the protein. Three types of lipid were chosen to change the surface charge of the polar group. The enzyme was immobilized on the lipid monolayer by adsorption from the subphase solution onto the lipid monolayer on the air/water interface. It was found that the lipid-enzyme interaction was dominated by electrostatic forces, and the characteristics of the film can be controlled by expansion and recompression of the adsorbed monolayer. Finally, a glucose sensor was fabricated by depositing the film onto a hydrogen peroxide electrode.
Journal of Electroanalytical Chemistry, 2008
Different immobilization procedures for horseradish peroxidase (HRP) were investigated using, as support matrices, self-assembled monolayers (SAM) formed on gold electrodes. The influences of these immobilization processes in the biosensor performance were also evaluated. For this, monolayers were prepared from thiols with different structures, carbon chain sizes and terminal groups. It was shown that the thiol carbon chain size influences especially in monolayer coverage and, consequently, in the biomolecule immobilization efficiency. From the studies carried out for SAM characterization on the electrode surface it was verified that thiols with shorter chains (n < 9) tend to form monolayers with a considerable amount of defects on the gold surface that lead to a lower coverage. However, thiols with a longer carbon chain present a higher coverage degree, which are not suited as substrate to the development of electrochemical biosensors, because they passivate the transduction interface, making difficult the electron transfer and, consequently, reducing electrode sensitivity. In relation to the enzyme immobilization on gold electrodes, it was verified, using different techniques, that monolayers that possess-NH 2 terminal groups provided the best results, probably due to the use of glutaraldeyde as ligand during the immobilization process. Analyzing biosensor performances for hydrogen peroxide, it was verified that SAM formed by cysteamine is the most adequate for HRP immobilization, because it provides better efficiency for enzyme immobilization associated to high sensitivity for H 2 O 2 .