A high-sensitive amperometric hydrogen peroxide biosensor based on the immobilization of hemoglobin on gold colloid/l-cysteine/gold colloid/nanoparticles Pt–chitosan composite film-modified platinum disk electrode

Design of a label-free aptasensor for electrochemical determination of hemoglobin: investigation of the peroxidase-like activity of hemoglobin for the sensing of different substrates

The unbalanced hemoglobin level in biological fluids can cause several diseases; hence it can be used as a biomarker for diagnosis. We aim, in the present study, to construct a label-free electrochemical aptasensor for the quantification of hemoglobin. For that, a conjugate of L-cysteine and gold nanoparticles was used for the aptamer immobilization on screen printed carbon electrodes. Using square wave voltammetry, the calibration plot was obtained and it was linear in the range of 50 ng ml^-1 to 36 000 ng ml^-1 while the detection limit was 1.2 ng ml^-1. After the binding of Hb on the modified screen-printed carbon electrode surface, the peroxidase-like activity of the bound hemoglobin was explored in the quantification of different substrates. Hydrogen peroxide and nitrite were chosen as model analytes. Amperometric measurements showed wide linear ranges: 0.2 μM-7.7 mM and 3.6 nM-1.3 mM for H₂O₂ and nitrite, respectively, with detection limits of 0.044 μM and 0.55 nM. In the proposed strategy, the aptamer provides excellent orientation and a biocompatible environment for hemoglobin whose catalytic activity plays a key role in H₂O₂ and nitrite analysis.

Synthesis of honeycomb Ag@CuO nanoparticles and their application as a highly sensitive and electrocatalytically active hydrogen peroxide sensor material

Copper acetate/silver nitrate/polyvinylpyrrolidone was first prepared into nano-hybrid silver-doped copper oxide by electrospinning, and then nano-honeycomb particles were produced through heat-treatment. For the first time, honeycomb Ag@CuO nanoparticles were prepared by electrospinning, and a H₂O₂ sensor was constructed by modifying the carbon paste electrode (CPE) with the honeycomb Ag@CuO nanoparticles. This work performed the structural, morphological, and phase analysis of the Ag@CuO nanoparticles by scanning electron microscopy (SEM) and X-ray diffraction (XRD). The results indicated the synthesis of Ag@CuO hybrid nanoparticles with high purity, and cyclic voltammetry and amperometry show that the Ag@CuO modified electrode has high electrocatalytic performances with fast voltammetric responses and a notably decreased overpotential compared to that of even the CuO modified CPE. In addition, the Ag/CuO-CPE based H₂O₂ sensor has the highest sensitivity of 1982.14 μA (mmol L^-1)^-1 cm^-2, the lowest detection limit of 0.01 μmol L^-1 ((S/N) = 3), and the measured linear response for H₂O₂ oxidation ranged from 0.05 μmol L^-1 to 100 μmol L^-1 and 100 μmol L^-1 to 1.5 mmol L^-1. The proposed method was applied to the determination of H₂O₂ in coconut fruit samples from canned coconut, and the satisfactory results confirmed the applicability of this sensor in practical analysis.

Immobilization of hemoglobin on MnCO3 sphere-loaded Au nanoparticles as highly efficient sensing platform towards hydrogen peroxide

In this paper, we report the synthesis of MnCO₃-Au hybrid microspheres and their application on the electrochemical biosensing of hydrogen peroxide (H₂O₂) based on the immobilization of hemoglobin (Hb). The characterization of MnCO₃-Au microspheres revealed that an abundance of Au nanoparticles (AuNPs) has been absorbed on the surface of the spherical MnCO₃ by the electrostatic assembly. The combined unique properties of MnCO₃-Au microspheres are beneficial for the realization of the direct electron transfer of Hb. Hb immobilized on the microspheres maintained its biological activity, showing a surface-controlled process with the heterogeneous electron transfer rate constant (k _s) of 2.63 s^-1. The fabricated biosensor displayed an excellent performance for the electrocatalytic reduction of H₂O₂. The linear range for the determination of H₂O₂ was from 0.06-40.0 μM with a detection limit of 0.015 µM (S/N = 3). The biosensor also exhibited high selectivity, good repeatability and long-term stability, which offers great potential for H₂O₂ detection in real sample analysis.

Double Biocatalysis Signal Amplification Glucose Biosensor Based on Porous Graphene

Controllable preparation of nanopores to promote the performance of electrochemical biosensing interfaces has become one of the researching frontiers in biosensing. A double biocatalysis signal amplification of glucose biosensor for the study of electrochemical behaviors of glucose oxidase (GOx) was proposed by using horseradish peroxidase biosynthesized porous graphene (PGR) as the platform for the biocatalytic deposition of gold nanoparticles (AuNPs). The biosensor showed a linear range from 0.25 to 27.5 μM with a detection limit of 0.05 μM (S/N = 3) towards glucose. Furthermore, the proposed AuNPs/GOx–PGR modified glassy carbon electrode (AuNPs/GOx–PGR/GCE) achieved direct electron transfer of GOx.

Intellectual modifying a bare glassy carbon electrode to fabricate a novel and ultrasensitive electrochemical biosensor: Application to determination of acrylamide in food samples

Acrylamide (AA) is a neurotoxin and carcinogen which is mainly formed in foods containing large quantities of starch processed at high temperatures and its determination is very important to control the quality of foods. In this work, a novel electrochemical biosensor based on hemoglobin-dimethyldioctadecylammonium bromide (HG-DDAB)/platinum-gold-palladium three metallic alloy nanoparticles (PtAuPd NPs)/chitosan-1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide (Ch-IL)/multiwalled carbon nanotubes-IL (MWCNTs-IL)/glassy carbon electrode (GCE) is proposed for ultrasensitive determination of AA in food samples. Development of the biosensor is based on forming an adduct by the reaction of AA with α-NH₂ group of N-terminal valine of HG which decreases the peak current of HG-Fe⁺³ reduction. The modifications were characterized by electrochemical impedance spectroscopy (EIS), cyclic voltammetry (CV), energy dispersive X-ray spectroscopic (EDS) and scanning electron microscopy (SEM). Under optimized conditions, the biosensor detected AA by square wave voltammetry (SWV) in two linear concentration ranges of 0.03-39.0nM and 39.0-150.0nM with a limit of detection (LOD) of 0.01nM. The biosensor was able to selective detection of AA even in the presence of high concentrations of common interferents which confirmed that the biosensor is highly selective. Also, the results obtained from further studies confirmed that the proposed biosensor has a short response time (less than 8s), good sensitivity, long term stability, repeatability, and reproducibility. Finally, the proposed biosensor was successfully applied to determine AA in potato chips and its results were comparable to those obtained by gas chromatography-mass spectrometry (GC-MS) as reference method.

Natural polyhydroxyalkanoate-gold nanocomposite based biosensor for detection of antimalarial drug artemisinin

The worrisome trend of antimalarial resistance has already highlighted the importance of artemisinin as a potent antimalarial agent. The current investigation aimed at fabricating a biosensor based on natural polymer polyhydroxyalkanoate-gold nanoparticle composite mounting on an indium-tin oxide glass plate for the analysis of artemisinin. The biosensor was fabricated using an adsorbing horse-radish peroxidase enzyme on the electrode surface for which cyclic voltammetry was used to monitor the electro-catalytic reduction of artemisinin under diffusion controlled conditions. Electrochemical interfacial properties and immobilization of enzyme onto a polyhydroxyalkanoate-gold nanoparticle film were evaluated, and confirmed by cyclic voltammetry, electrochemical impedance spectroscopy and scanning electron microscopy. The differential pulse voltammetric peak current for artemisinin was increased linearly (concentration range of 0.01-0.08μg mL(-1)) with sensitivity of 0.26μAμg mL(-1). The greater sensitivity of the fabricated biosensor to artemisinin (optimum limits of detection were 0.0035μg mL(-1) and 0.0036μg mL(-1) in bulk and spiked human serum, respectively) could be of much aid in medical diagnosis.

Horseradish Peroxidase Immobilization on Amine Functionalized Carbon Nano Tubes: Direct Electrochemistry and Bioelectrocatalysis

Horseradish peroxidase (HRP) was successfully immobilized on amine functionalized TiO2-coated multiwalled carbon nanotubes (NH2 TiO2 CNTs) by a convenient and efficient method. Electrochemical impedance spectroscopy, cyclic voltammetry and amperometry were applied to characterize the HRP/NH2- TiO2 - CNT nano-composite. These techniques showed that the NH2 TiO2CNTs greatly enhance the electron transfer between HRP and the modified electrode. Owing to the redox reaction of the electroactive centre of HRP, the HRP/NH2-TiO2-CNTs modified electrode exhibited a pair of quasi-reversible peaks with a peak-to-peak separation (Δ Ep) of 70.6 m V and a formal potential ( E°’) of - 367.65 m V (versus Ag/AgCl) in phosphate buffer solution. The charge transfer coefficient (a) and the apparent charge transfer rate constant (ks) were found to be 0.34 and 2.08 s-1 respectively. The prepared biosensor responded to H2O2 with a linear range, detection limit, sensitivity and response time of 1.0 × 10−9 to 1.0 × 10 −7 M, 0.786nM, 28.4 μA A nM−1 and 3 s, respectively.

[Sensor systems for medical application based on hemoproteins and nanocomposite materials]

Recent advances in nanotechnologies stimulate the development of sensor systems based on nanocomposite materials. This review discusses the prospects and challenges of sensors coupled with functionally important for medicine hemoproteins and nanoscale materials. Authors summarized their own experimental results and literature data on hemoprotein-based sensor systems. Mechanisms and the main function principles of electrochemical nanosensors are also discussed.

Direct electrochemistry and bioelectrocatalysis of horseradish peroxidase based on gold nano-seeds dotted TiO2 nanocomposite

Gold nano-seeds (GNSs) (capital EF, Cyrillic=2-5 nm) were dotted in TiO(2) colloids and the horseradish peroxidase (HRP) was successfully immobilized on the as-made GNSs-TiO(2) nanocomposite by a convenient and effective method. The matrix integrates the merits of both GNSs and TiO(2), which provides a favorable microenvironment for the immobilization of HRP. The cyclic votammetric results demonstrated that the entrapped HRP achieves direct electron transfer at glassy carbon electrode (GCE). A pair of stable and quasi-reversible redox peaks with a small peak-to-peak separation of 43 mV was observed in phosphate buffer solution. The GNSs stabilized by TiO(2) colloids acted sufficiently as the conducting tunnel to promote the electron transfer. As a result, the electrochemical behaviors were improved in virtue of the synergic effect of TiO(2) and GNSs. The Nafion/HRP-GNSs-TiO(2)/GCE displayed an excellent and rapid electrocatalytic response to the reduction of H(2)O(2). The proposed biosensor exhibited a good linear response in the range from 4.1 x 10(-5) to 6.3 x 10(-4) mol L(-1), with a detection limit of 5.9 x 10(-6) mol L(-1) (at the ration of signal to noise, S/N=3). The apparent Michaelis-Menten constant was estimated to be 0.63 mmol L(-1). Furthermore, the biosensor possesses satisfactory stability and good reproducibility.