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).

Effects of amyloid-β-mimicking peptide hydrogel matrix on neuronal progenitor cell phenotype.

Self-assembling peptide-based hydrogels have become a highly attractive scaffold for three-dimensional (3D) in vitro disease modeling as they provide a way to create tunable matrices that can resemble the extracellular matrix (ECM) of various microenvironments. Alzheimer's disease (AD) is an exceptionally complex neurodegenerative condition; however, our understanding has advanced due to the transition from two-dimensional (2D) to 3D in vitro modeling. Nonetheless, there is a current gap in knowledge regarding the role of amyloid structures, and previously developed models found long-term difficulty in creating an appropriate model involving the ECM and amyloid aggregates.

Divalent metal ion modulation of a simple peptide-based hydrogel: self-assembly and viscoelastic properties.

Peptide self-assembly has been highly studied to understand the pathways in forming higher order structures along with the development and application of resulting hydrogel materials. Driven by noncovalent interactions, peptide hydrogels are stimuli-responsive to any addition to its gelling conditions. Here, a Phe-His based peptide, C-FH(Trt)-OH, was synthesized and characterized with H NMR, FT-IR, MS, UV-vis spectroscopies and elemental analysis.

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).

Palladium-Copper Bimetallic Aerogel as New Modifier for Highly Sensitive Determination of Bisphenol A in Real Samples.

In this study, a bimetallic palladium-copper aerogel was synthesized and used for modification of a graphite paste electrode (Pd-Cu/GPE), allowing the sensitive determination of bisphenol A (BPA). Different techniques, such as SEM, TEM, XPS, and AFM, were used for characterization of the Pd-Cu aerogel. To elucidate the properties of the Pd-Cu/GPE, the electrochemistry methods such as differential pulse voltammetry (DPV) and electrochemical impedance spectroscopy were used.

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.

Peptide Hydrogels as Immunomaterials and Their Use in Cancer Immunotherapy Delivery.

Peptide-based hydrogel biomaterials have emerged as an excellent strategy for immune system modulation. Peptide-based hydrogels are supramolecular materials that self-assemble into various nanostructures through various interactive forces (i.e.

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.

Microencapsulation of Probiotic LAB813.

Probiotics are living microorganisms that confer a health benefit on the host when administered in adequate amounts. , a commensal bacterium found in the oral cavity, has been shown to secrete antimicrobial peptides and can be used as probiotics. This study aimed to develop a delivery system for the probiotic LAB813, a novel strain first identified in the laboratory.

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).

Development of a Bacterial Enzyme-Based Biosensor for the Detection and Quantification of Selenate.

An enzymatic biosensor has been developed for the determination of selenate (SeO ), in which selenate reductase (SeR) is chemically attached to a gold disk electrode by lipoic acid N-hydroxysuccinimide ester as linker, allowing the catalytic reduction of the SeO to SeO . Modification of the gold electrode was characterized by X-ray photoelectron spectroscopy (XPS), time-of-flight secondary ion mass spectroscopy (ToF-SIMS), and electrochemistry. Cyclic voltammetry (CV) and differential pulse voltammetry (DPV) measurements were performed in different buffers for selenate determination.

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.

Peptide-Polydopamine Nanocomposite Hydrogel for a Laser-Controlled Hydrophobic Drug Delivery.

Smart antibacterial systems, delivering antimicrobials in a highly controlled manner, are one strategy toward fighting the rise of antibiotic-resistant pathogens. Here, we engineer a laser-responsive antimicrobial nanocomposite hydrogel combining a peptide amphiphile and a photothermally active polydopamine nanoparticle (PDNP) to entrap the hydrophobic rifampicin within the hydrophilic hydrogel matrix. We show that the ability of the gelator to interact and retain rifampicin within the gel induced structural changes in its nanofiber network and mechanical properties.

Metal-dependent electrochemical discrimination of DNA quadruplex sequences.

Films of four different DNA quadruplex-forming (G4) sequences (c-KIT, c-MYC, HTelo, and BCL2) on gold surfaces were investigated by electrochemical impedance spectroscopy (EIS) to evaluate whether they evoke unique electrochemical responses that can be used for their identification. This could render EIS an alternative means for the determination of G4 sequences of unknown structure. Towards, this end, cation-dependent topology changes in the presence of either K, K in combination with Li, or Pb in the presence of Li were first evaluated by circular dichroism (CD) spectroscopy, and electrochemical studies were performed subsequently.

Nanoporous Gold for the Miniaturization of In Vivo Electrochemical Aptamer-Based Sensors.

Electrochemical aptamer-based sensors enable real-time molecular measurements in the living body. The spatial resolution of these measurements and ability to perform measurements in targeted locations, however, is limited by the length and width of the device's working electrode. Historically, achieving good signal to noise in the complex, noisy in vivo environment has required working electrode lengths of 3-6 mm.

Development of a novel label-free impedimetric electrochemical sensor based on hydrogel/chitosan for the detection of ochratoxin A.

Ochratoxin A (OTA) is one of the most abundant mycotoxins that contaminate various food products. Herein, we propose a novel label-free impedimetric electrochemical sensor consisting of chitosan/dipeptide nanofibrous hydrogel and immobilized DNA probes with OTA aptamer for the detection of OTA. The thin film of chitosan/dipeptide nanofibrous hydrogel was used as sensing interface and carrier for hybridization chain reaction (HCR) of OTA aptamer and DNA2 strand to form DNA concatemer.

Consecutive Silver(I) Ion Incorporation into Oligonucleotides containing Cytosine-Cytosine Mispairs.

Invited for this month's cover is the group of Prof. Heinz-Bernhard Kraatz from the University of Toronto, Canada. The cover picture shows the consecutive incorporation of Ag ions into a DNA duplex containing adjacent C-C mispairs.

A novel electrochemical immunosensor for hepatitis B surface antigen based on FeO nanoflowers and heterogeneous chain reaction signal amplification strategy.

Herein, a novel sandwich-type electrochemical immunosensor was fabricated based on FeO nanoflowers (FeO NFs) and heterogeneous chain reaction (HCR) signal amplification strategy for the sensitive detection of hepatitis B surface antigen (HBsAg). The aldehyde-functionalized FeO NFs are used as a supporting matrix to immobilize the hepatitis B surface antibody 1 (HBsAb1). The biotin-modified single-strand DNA (biotin-S0) was connected onto the biotin-HBsAb2 via linkage of streptavidin (SA), followed by addition of methylene blue (MB) modified single strand DNA1 (MB-S1) and DNA2 (MB-S2) for HCR signal amplification.

Homogeneous and heterogeneous molecular catalysts for electrochemical reduction of carbon dioxide.

Carbon dioxide (CO) is a greenhouse gas whose presence in the atmosphere significantly contributes to climate change. Developing sustainable, cost-effective pathways to convert CO into higher value chemicals is essential to curb its atmospheric presence. Electrochemical CO reduction to value-added chemicals using molecular catalysis currently attracts a lot of attention, since it provides an efficient and promising way to increase CO utilization.

Consecutive Silver(I) Ion Incorporation into Oligonucleotides containing Cytosine-Cytosine Mispairs.

Herein, the consecutive incorporation of Ag ion into the dsDNA containing adjacent C-C mispairs is demonstrated. The melting temperature (T ) was 8  C higher for DNA containing three C-C mispairs upon the addition of three Ag ions as compared to the Ag -free DNA, and no T was obtained in the presence of excess Ag ion, indicating a stable bridging of C-Ag -C upon the incorporation of the stoichiometric amount of Ag per C-C mispair. The circular dichroism (CD) spectra of the dsDNA showed a negative peak at ∼270 nm in the presence of excess Ag , implying that significant structural changes and a potential aggregation of DNA occurred.

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.

Electrochemical Reduction of CO at Coinage Metal Nanodendrites in Aqueous Ethanolamine.

Electrocatalytic reduction of CO into usable chemicals is a promising path to address climate change and energy challenges. Herein, we demonstrate the synthesis of unique coinage metal (Cu, Ag, and Au) nanodendrites (NDs) via a facile galvanic replacement reaction (GRR), which can be effective electrocatalysts for the reduction of CO in an ethanolamine (EA) solution. Each metal ND surface was directly grown on glassy-carbon (GC) substrates from a mixture of Zn dust and the respective precursor solution.

Multi-component peptide hydrogels - a systematic study incorporating biomolecules for the exploration of diverse, tuneable biomaterials.

Peptide-based supramolecular gels can be designed to be functional "smart" materials that have applications in drug delivery, tissue engineering, and supramolecular chemistry. Although many multi-component gel systems have been designed and reported, many of these applications still rely solely on single-component gel systems which limits the functionalities of the materials. Multi-component self-assembly leads to the formation of highly ordered and complex architectures while offering the possibility to generate hydrogels with interesting properties including functional complexity and diverse morphologies.