An electrochemical immunosensor based on reduced graphene oxide/multiwalled carbon nanotubes/thionine/gold nanoparticle nanocomposites for the sensitive testing of follicle-stimulating hormone

An ultrasensitive unlabeled electrochemical immunosensor for the detection of cardiac troponin I based on Pt/Au-B,S,N-rGO as the signal amplification platform

In this study, an ultrasensitive unlabeled electrochemical immunosensor for the detection of cardiac troponin I (cTnI) was developed based on Pt/Au modified B,S,N co-doped reduced graphene oxide (Pt/Au-B,S,N-rGO) as a signal amplification platform. First-principles calculations were employed to analyze the electron density of states of Pt/Au-B,S,N-rGO, revealing an increase in the electron density of the graphene oxide (GO) states. Furthermore, scanning electron microscopy (SEM), X-ray photoelectron diffraction spectroscopy (XPS), and electrochemical detection were used to successfully construct and analyze Pt/Au-B,S,N-rGO. The results showed that B,S,N-rGO exhibited good electrochemical activity, and the Au/Pt NPs demonstrated excellent catalytic properties, which provided a strong foundation for achieving high-sensitivity detection. Moreover, the constructed unlabeled electrochemical immunosensor had an ideal linear range (0.1 pg/mL∼50 ng/mL) and detection limit (0.082 pg/mL). In human serum detection, the results of this immunosensor were essentially similar to the ELISA results for the same samples, which suggested that the immunosensor had a promising clinical application prospect for the detection of cTnI.

Effects of nanotubes on semen quality and fertility in humans: A systematic review of literature

BACKGROUND

In the medical field, it is increasingly common to observe the use of nanotubes, for example, in the administration of drugs. However, nanotubes raise concerns for male fertility due to potential effects on hormone levels and sperm quality observed in animal studies. In addition, animal exposure to multi-walled carbon nanotube models found alterations in hormone levels, sperm motility, and sperm count. Limited evidence in humans suggests no adverse effects, but further research is needed. This study aimed to perform a systematic review to assess the in vitro effects of nanotubes on semen and fertility in humans.

METHODS

We included all published in vitro studies about semen or sperm or male fertility and nanotubes in humans. A search was conducted in LILACS, PubMed, and SCOPUS as of May 2023. The risk of bias was assessed using the QUIN tool.

RESULTS

Four studies using nanotubes on human sperm were included, nanotubes exposure appears not to affect sperm viability; however, some alterations to motility, velocity and production of reactive oxygen species were reported. Limited evidence is provided because of the small quantity of publications.

CONCLUSIONS

Nanotubes appear to have no adverse effects on human sperm.

Carbon Nanomaterials-Based Screen-Printed Electrodes for Sensing Applications

Electrochemical sensors consisting of screen-printed electrodes (SPEs) are recurrent devices in the recent literature for applications in different fields of interest and contribute to the expanding electroanalytical chemistry field. This is due to inherent characteristics that can be better (or only) achieved with the use of SPEs, including miniaturization, cost reduction, lower sample consumption, compatibility with portable equipment, and disposability. SPEs are also quite versatile; they can be manufactured using different formulations of conductive inks and substrates, and are of varied designs. Naturally, the analytical performance of SPEs is directly affected by the quality of the material used for printing and modifying the electrodes. In this sense, the most varied carbon nanomaterials have been explored for the preparation and modification of SPEs, providing devices with an enhanced electrochemical response and greater sensitivity, in addition to functionalized surfaces that can immobilize biological agents for the manufacture of biosensors. Considering the relevance and timeliness of the topic, this review aimed to provide an overview of the current scenario of the use of carbonaceous nanomaterials in the context of making electrochemical SPE sensors, from which different approaches will be presented, exploring materials traditionally investigated in electrochemistry, such as graphene, carbon nanotubes, carbon black, and those more recently investigated for this (carbon quantum dots, graphitic carbon nitride, and biochar). Perspectives on the use and expansion of these devices are also considered.

Advances on Hormones and Steroids Determination: A Review of Voltammetric Methods since 2000

This article presents advances in the electrochemical determination of hormones and steroids since 2000. A wide spectrum of techniques and working electrodes have been involved in the reported measurements in order to obtain the lowest possible limits of detection. The voltammetric and polarographic techniques, due to their sensitivity and easiness, could be used as alternatives to other, more complicated, analytical assays. Still, growing interest in designing a new construction of the working electrodes enables us to prepare new measurement procedures and obtain lower limits of detection. A brief description of the measured compounds has been presented, along with a comparison of the obtained results.

An Innovative Sandwich Type Biosensor towards Sensitive and Selective Monitoring of 2-Arachidonoylglycerol in Human Plasma Samples Using P(β-CD)-AuNPs-DDT as Amplificant Agent: A New Immuno-Platform for the Recognition of Endocannabinoids in Real Samples

In this work, 2-AG was successfully detected in human plasma samples using a new sandwich-type electrochemical immune device based on poly-β-cyclodextrin P(β-CD) functionalized with AuNPs-DDT and toluidine blue. The P(β-CD) ensured the bioactivity and stability of the immobilized 2-AG antibody by providing a broad surface for the efficient immobilization of the biotinylated antibody. To complete the top section of the immunosensor (reporter), an HRP-conjugated antibody of 2-AG (secondary antibody (Ab2)) was attached to the surface of a glassy carbon electrode (GCE) modified by P(β-CD), as well as a primarily biotinylated antibody (Ab1). The biosensor fabrication process was monitored using field-emission scanning electron microscope (FE-SEM) and EDS methods. Using the differential pulse voltammetry technique, the immunosensor was utilized for detection of 2-AG in real samples. The suggested interface increased the surface area, which allowed for the immobilization of a large quantity of anti-2-AG antibody while also improving biocompatibility, stability, and electrical conductivity. Finally, the suggested immunosensor’s limit of quantitation was determined to be 0.0078 ng/L, with a linear range of 0.0078 to 1.0 ng/L. The results showed that the suggested bioassay can be utilized for diagnosis of 2-AG in clinical samples as a unique and ultrasensitive electrochemical biodevice.

Dual-template molecularly imprinted electrochemical biosensor for IgG-IgM combined assay based on a dual-signal strategy

Detection of immunoglobulins (Igs) is of clinical significance for early diagnosis and timely treatment of diseases. Herein, a dual-template molecularly imprinted (DTMI) electrochemical biosensor was developed for IgG-IgM combined assay. In this DTMI electrochemical biosensor, Prussian blue (PB) and thionine (TH) decorated on graphene oxide (GO) and multi-walled carbon nanotubes (MWCNTs), respectively, were utilized as the dual-signal probes, and Au nanoparticles (AuNPs) were used for Igs anchoring and signal amplification. Polypyrrole (PPy) was electrodeposited on the biosensor surface and acted as the molecularly imprinted polymers (MIPs). After the removal of the IgG and IgM templates, the resultant DTMI electrochemical biosensor was used for IgG-IgM combined assay, and the concentrations of IgG and IgM could be indicated by the changes in the peak currents of PB (ΔI_PB) and TH (ΔI_TH), respectively. The DTMI electrochemical biosensor displayed a wide linear range and a low limit of detection (LOD) for both IgG (28.80 pg mL^-1) and IgM (0.58 pg mL^-1). Finally, the developed DTMI biosensor was used for IgG-IgM combined assay in clinical serum samples, and the results were comparable to those obtained by conventional immunoturbidimetry, implying its great potential in clinical diagnosis.