Zero-Biased Photoelectrochemical Detection of Cardiac Biomarker Myoglobin Based on CdSeS/ZnS Quantum Dots and Barium Titanate Perovskite

Cardiovascular diseases are considered one of the leading causes of premature mortality of patients worldwide. Therefore, rapid diagnosis of these diseases is crucial to ensure the patient's survival. During a heart attack or severe muscle damage, myoglobin is rapidly released in the body to constitute itself as a precise biomarker of acute myocardial infarction. Thus, we described the photoelectrochemical immunosensor development to detect myoglobin. It was based on fluorine-doped tin oxide modified with CdSeS/ZnSe quantum dots and barium titanate (BTO), designated as CdSeS/ZnSQDS/BTO. It was characterized by scanning electron microscopy (SEM), energy-dispersive spectroscopy (EDX), transmission electron microscopy (TEM), X-ray diffraction (XRD), electrochemical impedance spectroscopy (EIS), and amperometry. The anodic photocurrent at the potential of 0 V (vs. Ag/AgCl) and pH 7.4 was found linearly related to the myoglobin (Mb) concentration from 0.01 to 1000 ng mL^-1. Furthermore, the immunosensor showed an average recovery rate of 95.7-110.7% for the determination of myoglobin.

Current advances in bio-fabricated quantum dots emphasising the study of mechanisms to diversify their catalytic and biomedical applications

Quantum dots (QDs), owing to their single atom-like electronic structure due to quantum confinement, are often referred to as artificial atoms. This unique physical property results in the diverse functions exhibited by QDs. A wide array of applications have been achieved by the surface functionalization of QDs, resulting in exceptional optical, antimicrobial, catalytic, cytotoxic and enzyme inhibition properties. Ordinarily, traditionally prepared QDs are subjected to post synthesis functionalization via a variety of methods, such as ligand exchange or covalent and non-covalent conjugation. Nevertheless, solvent toxicity, combined with the high temperature and pressure conditions during the preparation of QDs and the low product yield due to multiple steps in the functionalization, limit their overall use. This has driven scientists to investigate the development of greener, environmental friendly and cost-effective methods that can circumvent the complexity and strenuousness associated with traditional processes of bio-functionalization. In this review, a detailed analysis of the methods to bio-prepare pre-functionalized QDs, with elucidated mechanisms, and their application in the areas of catalysis and biomedical applications has been conducted. The environmental and health and safety aspects of the bio-derived QDs have been briefly discussed to unveil the future of nano-commercialization.

Microwave-assisted synthesis of PbS nanostructures

The synthesis of PbS nanostructures by microwave irradiation of single source precursor compounds in ethyleneglycol medium is reported. Pb(II) bis(N-ethyl-N-phenyldithiocarbamate) and Pb(II) bis(N-butyl-N-phenyldithiocarbamate) represented as complexes (1) and (2) respectively were utilised. The prepared PbS nanostructures were characterized using X-ray diffraction (XRD), Transmission electron microscopy (TEM), and absorption spectroscopy. The results showed that complex (1) can project the formation of nanorod with (111) basal plane, while (2) project the formation of nanocube with (001) basal plane. The formation of different morphologies in ethylene glycol may also be due to the selective binding to specific crystallite facets of the PbS through the hydroxyl groups of ethylene glycol. In the nanorod, the selective stabilization of the (111) face of PbS, resulted in anisotropic growth along the (100) face. The high resolution TEM images showed distinct lattice fringes which confirmed the crystallinity of the nanostructures. The band gap energies were obtained as 1.10 and 1.12 eV for the nanorods and nanocubes respectively, a significant blue shift from the bulk value (0.4 eV) which could be ascribed to quantum confinement effect. The result established the significant effect of the precursor type on the morphologies of the PbS.

Dual-emission ratiometric fluorescence detection of aspirin in human saliva: onsite naked-eye detection and high stability

A highly stable ratiometric fluorescence probe based on dual-emission QDs was designed for the visual detection of aspirin in human saliva.