One-pot preparation of Au-Pt bimetallic single-atom nanozymes with efficient peroxidase-like activity using chitosan and l-tyrosine as carriers for visual and colorimetric detection of quercetin.

An one-pot method was used to prepare bimetallic nanozymes, with chitosan (CS) and l-tyrosine (L-Tyr) as stabilized dispersed colloidal solutions and a carrier for gold-platinum single atoms (Au-Pt SAs), which exhibited excellent peroxidase activity. A colorimetric method based on CS/L-Tyr/Au-Pt SAs nanozymes was constructed for the colorimetric detection of quercetin (QR) in human serum and orange juice. The synthesized bimetallic nanozymes were characterized by SEM, TEM, HAADF-STEM, FT-IR, XRD and XPS techniques to demonstrate the successful synthesis of CS/L-Tyr/Au-Pt SAs nanozymes.

3D printed electrochemical sensor and microfluidic system for the detection of L-tryptophan using degradable material.

Herein, we constructed an integrated system for L-tryptophan (L-Trp) detection by assembling an electrochemical sensor and a microfluidic platform. Amongst, the sensor was printed using conductive polymer filaments and then chemically activated to expose porous nanostructure on the surface. A calibration curve was established between 31.

Construction and evaluation of AuNPs enhanced electrochemical immunosensors with [Fe(CN)] and PPy probe for highly sensitive detection of human chorionic gonadotropin.

Human chorionic gonadotropin (HCG), a vital protein for pregnancy determination and a marker for trophoblastic diseases, finds application in monitoring early pregnancy and ectopic pregnancy. This study presents an innovative approach employing electrochemical immunosensors for enhanced HCG detection, utilizing Anti-HCG antibodies and gold nanoparticles (AuNPs) in the sensor platform. Two sensor configurations were optimized: BSA/Anti-HCG/c-AuNPs/MEL/e-AuNPs/SPCE with [Fe(CN)] as a redox probe (1) and BSA/Anti-HCG/PPy/e-AuNPs/SPCE using polypyrrole (PPy) as a redox probe (2).

Electrochemical immuno-biosensors for the detection of the tumor marker alpha-fetoprotein: A review.

Alpha-fetoprotein (AFP) is a glycoprotein that has many important physiological functions, including transportation, immunosuppression, and induction of apoptosis by T lymphocytes. AFP is closely related to the development of hepatocellular carcinoma and many kinds of tumors, all of which can show high concentrations, so it is used as a positive test indicator for many kinds of tumors. This paper reviews recent advances in the detection of the tumor marker AFP based on three immuno-biosensors: electrochemical (EC), photoelectrochemical (PEC), and electrochemical luminescence (ECL).

A simple synthesis of a core-shell structure PPy-Au nanocomposite for immunosensing of C-reactive protein.

High-sensitivity C-reactive protein (hs-CRP) is an inflammatory biomarker and can accurately predict the development of cardiovascular disease (CVD). We synthesized a core-shell structure PPy-Au nanocomposite in situ by chemically oxidizing pyrrole (Py) with HAuCl and the produced Au nanoparticles realized the doping in the polymerization. Analysis of morphology and energy spectrum as well as electrochemical characterization confirmed the successful one-pot synthesis.

Electrochemical sensor for ultrasensitive sensing of biotin based on heme conjugated with gold nanoparticles and its electrooxidation mechanism.

We report the fabrication of a facile sensor using heme conjugated with gold nanoparticles (AuNPs) in situ on a glass carbon electrode (GCE) for the ultrasensitive determination of biotin without antibody or streptavidin. The use of heme and AuNPs as dual amplifiers allows a very broad detection range from 0.0050 to 50.

A facile indole probe for ultrasensitive immunosensor fabrication toward C-reactive protein sensing.

C-reactive protein (CRP) is a protein biomarker for acute phase response. Herein, we fabricate a highly sensitive electrochemical immunosensor for CRP on a screen-printed carbon electrode (SPCE) with indole as a novel electrochemical probe and Au nanoparticles for signal amplification. Amongst, indole appeared as transparent nanofilms on the electrode surface, and underwent a one-electron and one-proton transfer to form oxindole during the oxidation process.

Facile bimetallic co-amplified electrochemical sensor for folic acid sensing based on CoNPs and CuNPs.

Folic acid (FA) is essential for human health, particularly for pregnant women and infants. In this work, a glassy carbon electrode (GCE) was modified by a bimetallic layer of Cu/Co nanoparticles (CuNPs/CoNPs) as a synergistic amplification element by simple step-by-step electrodeposition, and was used for sensitive detection of FA. The proposed CuNPs/CoNPs/GCE sensor was characterized by differential pulse voltammetry (DPV), electrochemical impedance spectroscopy (EIS) and field emission scanning electron microscopy (FESEM).

Enzyme-free glucose sensors with efficient synergistic electro-catalysis based on a ferrocene derivative and two metal nanoparticles.

Gold electrodes (GE) were modified by the deposition of copper nanoparticles (CuNPs) and cobalt nanoparticles (CoNPs), followed by drop-casting of the ferrocene derivative FcCO-Glu-Cys-Gly-OH (Fc-ECG), resulting in two enzyme-free electrochemical sensors Fc-ECG/CuNPs/GE and Fc-ECG/CuNPs/GE. The ferrocene-peptide conjugate acts as an effective redox mediator for glucose oxidation, while metal nanoparticles acted as non-biological sites for glucose oxidation. Field emission scanning electron microscopy (FESEM), cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) were carried out for characterization, while differential pulse voltammetry (DPV) was used for glucose quantification.

One step construction of an electrochemical sensor for melamine detection in milk towards an integrated portable system.

Excessive intake of melamine (MEL) can be harmful to human health, and it is important to establish a rapid and accurate MEL detection method. As the electrochemical activity of MEL is very low, ferrocenylglutathione (Fc-ECG) was used as an electron transfer mediator to assist with the detection of MEL using screen-printed carbon electrode (SPCE). This modified electrode (MEL/Fc-ECG/SPCE) was prepared by stepwise drop-casting and was fully characterized.

Convenient Heme Nanorod Modified Electrode for Quercetin Sensing by Two Common Electrochemical Methods.

Quercetin (Qu) is one of the most abundant flavonoids in the human diet. High concentrations of Qu can easily cause adverse effects and induce inflammation, joint pain and stiffness. In this study, Heme was used as a sensitive element and deposited and formed nanorods on a glassy carbon electrode (GCE) for the detection of Qu.

infection with atrophic gastritis: An independent risk factor for colorectal adenomas.

Background: The significance of () infection and atrophic gastritis (AG) in the prevalence of colorectal adenomas has been examined in a limited number of studies. However, these studies reported disputed conclusions.

Aim: To investigate whether infection, AG, and -related AG increase the risk of colorectal adenomas.

The construction of a simple sensor for the simultaneous detection of nitrite and thiosulfate by heme catalysis.

Several simple sensors were fabricated through a one-step method. By depositing electro-active compounds, such as β-cyclodextrins (β-CD), heme, dopamine (DA), or Fc-ECG, onto a screen-printed electrode (SPE), the successful simultaneous detection of nitrite (NO ) and thiosulfate (SO ) ions was observed. Under optimal operating conditions, the notable electrocatalytic abilities of a Heme/SPE sensor were detected for the oxidation of NO and SO , with remarkable peak potential differences, after characterization SEM, CV, and DPV.

Real-Time Electrochemical Detection of Uric Acid, Dopamine and Ascorbic Acid by Heme Directly Modified Carbon Electrode.

Several simple electrochemical sensors were designed for three analytes, uric acid (UA), dopamine (DA) and ascorbic acid (AA) detection via electrolytic deposition of three functional materials heme, Fc(Cys)₂ and Fc-ECG onto glassy carbon electrodes (GCEs) without other medium. Characterization of the modified GCEs was conducted using SEM, TEM and DPV methods. Results showed that the heme/GCE demonstrated notable electro-catalytic capabilities, towards DA, AA, and UA oxidation in a solution of phosphate buffer.

A Facile Electrochemical Sensor Labeled by Ferrocenoyl Cysteine Conjugate for the Detection of Nitrite in Pickle Juice.

Simple and facile electrochemical sensors for nitrite detection were fabricated by directly depositing ferrocenoyl cysteine conjugates Fc[CO-Cys(Trt)-OMe]₂ [Fc(Cys)₂] or Fc[CO-Glu-Cys-Gly-OH] [Fc-ECG] on screen-printed electrodes (SPEs). The modified carbon electrodes were characterized by scanning electron microscopy (SEM), cyclic voltammetry (CV) and differential pulse voltammetry (DPV). Results indicated that Fc-ECG/SPE sensor showed enhanced current response and a lower overpotential than Fc(Cys)₂/SPE sensor for nitrite detection.

The Effects of Group-Based versus Individual-Based Tai Chi Training on Nonmotor Symptoms in Patients with Mild to Moderate Parkinson's Disease: A Randomized Controlled Pilot Trial.

Objective: To compare the effects of group-based and individual-based Tai Chi training on nonmotor symptoms in patients with mild to moderate Parkinson's disease.

Design: Randomized controlled pilot study.

Methods: 36 community-dwelling patients with Parkinson's disease (PD) were randomly assigned to either group-based training group ( = 19) or individual-based group ( = 17).

A sensitive and selective electrochemical biosensor for the determination of beta-amyloid oligomer by inhibiting the peptide-triggered in situ assembly of silver nanoparticles.

Soluble beta-amyloid (Aβ) oligomer is believed to be the most important toxic species in the brain of Alzheimer's disease (AD) patients. Thus, it is critical to develop a simple method for the selective detection of Aβ oligomer with low cost and high sensitivity. In this paper, we report an electrochemical method for the detection of Aβ oligomer with a peptide as the bioreceptor and silver nanoparticle (AgNP) aggregates as the redox reporters.

Interaction Study of Ferrocene Derivatives and Heme by UV-Vis Spectroscopy.

The interaction between ferrocene derivatives, such as Fc(COOH)2(λmax=286 nm), Fc(OBt)2(λmax=305 nm), Fc(Cys)(λmax=289 nm) and heme(λmax=386 nm) were studied by UV-Vis spectroscopy, respectively. The results show that, when the concentration of heme is fixed, the absorbance of heme increases with the increase of Fc(COOH)2 and Fc(Cys) concentration, the absorbance of heme almost keep the same when Fc(OBt)2 concentration increases; when the concentration of ferrocene derivatives are fixed, the absorbance of Fc(COOH)2 and Fc(Cys) also increases with the increase of heme concentration, the absorbance of Fc(OBt)2 almost keep the same when heme concentration increase. It is demonstrated that the hydrogen bonding interactions happen between Fc(COOH)2, Fc(Cys) and heme, none of Fc(OBt)2, the formation of hydrogen bonding lead to the growth of molecular chain, the bigger molecule can absorb more energy and increase the absorbance.

Determination of Residual Solvents in Linezolid by Static Headspace GC.

A headspace gas chromatographic method was developed for the determination of residual solvents in linezolid active substances. The solvents include petroleum ether (60-90°C), acetone, tetrahydrofuran, ethyl acetate, methanol, dichloromethane (DCM) and pyridine. The method showed the possibility to detect the tested solvents with a linear determination correlation coefficient (r) greater than 0.

Polymorphism of flucloxacillin sodium.

The polymorphism of flucloxacillin sodium has not been discussed sufficiently so far. Flucloxacillin sodium which was crystallized with different solvents, was found to exist in amorphism and three crystal forms (I, II, III). This results were confirmed by infra-red (IR) spectra, thermogravimetry (TG), X-ray diffraction analysis (XRD) and equilibrium solubility.

{2-[(3,5-Dichloro-2-oxidobenzyl-idene)amino-κN,O]-3-methyl-penta-noato-κO}(N,N'-dimethyl-formamide-κO)copper(II).

In the title compound, [Cu(C(13)H(13)Cl(2)NO(3))(C(3)H(7)NO)], the Cu(II) atom is coordinated in a slightly distorted square-planar geometry by two O atoms and one N atom from the tridentate chiral ligand 2-[(3,5-dichloro-2-oxidobenzyl-idene)amino]-3-methyl-penta-noate and by one O atom from dimethyl-formamide. In the crystal structure, the Cu atom forms contacts with Cl and O atoms of two units (Cu⋯Cl and Cu⋯O = 3.401 and 2.