Facile one-step synthesis of quaternary AgInZnS quantum dots and their applications for causing bioeffects and detecting Cu2

Biosynthesis of Quantum Dots and Their Therapeutic Applications in the Diagnosis and Treatment of Cancer and SARS-CoV-2

Quantum dots (QDs) are semiconductor materials that range from 2 nm to 10 nm. These nanomaterials (NMs) are smaller and have more unique properties compared to conventional nanoparticles (NPs). One of the unique properties of QDs is their special optoelectronic properties, making it possible to apply these NMs in bioimaging. Different size and shape QDs, which are used in various fields such as bioimaging, biosensing, cancer therapy, and drug delivery, have so far been produced by chemical methods. However, chemical synthesis provides expensive routes and causes serious environmental and health issues. Therefore, various biological systems such as bacteria, fungi, yeasts, algae, and plants are considered as potent eco-friendly green nanofactories for the biosynthesis of QDs, which are both economic and environmentally safe. The review aims to provide a descriptive overview of the various microbial agents for the synthesis of QDs and their biomedical applications for the diagnosis and treatment of cancer and SARS-CoV-2.

High selectivity and fluorescence reversible Eu3+ sensor based on GSH-capped AgZnInS QDs

Fluorescence sensors for trivalent europium ions (Eu³⁺) are seldom reported. We study the synthesis of water-soluble quaternary quantum dots (QDs) and investigate their fluorescence sensor application for detecting Eu³⁺ The as-synthesized glutathione (GSH)-capped AgZnInS (AZIS) QDs show great sensitivity and selectivity to Eu³⁺among 12 different metal cations. Detailed experimental results indicate that the fluorescence response of the AZIS QDs to increasing concentration of Eu³⁺ ([Eu³⁺]) include intensity quenching and peak wavelength blueshift. With the addition of OH-, the fluorescence response reverses. Electron transfer is considered to be the mechanism for the fluorescence quenching and peak wavelength blueshift of the GSH-capped AZIS QDs. Our work provides a new, to the best of our knowledge, method for the detection of Eu³⁺.

Pb2+ Responsive Cu-In-Zn-S Quantum Dots With Low Cytotoxicity

Water-soluble Cu-In-Zn-S quantum dots (CIZS QDs) with orange fluorescence have been synthesized with a glutathione (GSH) as stabilizer via facile a one-step hydrothermal method. The optimal reaction conditions of CIZS QDs including temperature, time, pH, and the molar ratios of precursors were studied. TEM results indicate that the aqueous-dispersible CIZS QDs are quasi-spherical, and the average diameters are 3.76 nm with excellent fluorescent stability. Furthermore, the cytotoxicity of CIZS QDs was investigated by the microcalorimetry combining with TEM and the IC50 was 10.2 μM. CIZS QDs showed a promising perspective in applications such as a fluorescent probe for bioimaging and biolabeling due to the low cytotoxicity and good biocompatibility. Moreover, the CIZS QDs can distinguish Pb2+ ion from other ions, offering great potentials in lead ion determination in drinking water. According to the results of UV, XRD, FL, PL, and ITC methods, the mechanism of CIZS QDs-Pb2+ assay is due to hydrogen bonding or van der Waals forces in the formation of Pb2+ and CIZS QDs.

A review on I–III–VI ternary quantum dots for fluorescence detection of heavy metals ions in water: optical properties, synthesis and application

Ternary I–III–VI quantum dots used in the fluorescence detection of heavy metals ions in water.

A fluorometric assay for α-glucosidase activity based on quaternary AgInZnS QDs

A sensitive fluorescence strategy was constructed for the detection of α-glucosidase activity based on AgInZnS QDs. The AIZS QDs which were synthesized by hydrothermal method have a fluorescence emission wavelength of 554 nm. Ce⁴⁺ was able to oxidize p-phenylenediamine (PPD) to generate oxPPD, which can quench the fluorescence of AIZS QDs through dynamic quenching. When α-glucosidase was introduced into the system, L-ascorbic acid-2-O-α-D-glucopyranosyl (AAG) could be hydrolyzed to form ascorbic acid (AA), which can reduce Ce⁴⁺ and prevent the oxidation of PPD. Thus, the dynamic quenching process was blocked accompanying with the fluorescence recovery of AIZS QDs. The developed detection system for α-glucosidase displayed a good linear relationship between 0.01 and 0.16 U·mL^-1 with a detection limit of 0.0073 U·mL^-1. The sensing platform with high feasibility and anti-interference is a competitive alternative applied to α-glucosidase-related diagnostics.

Biosensors Based on Advanced Sulfur-Containing Nanomaterials

In recent years, sulfur-containing nanomaterials and their derivatives/composites have attracted much attention because of their important role in the field of biosensor, biolabeling, drug delivery and diagnostic imaging technology, which inspires us to compile this review. To focus on the relationships between advanced biomaterials and biosensors, this review describes the applications of various types of sulfur-containing nanomaterials in biosensors. We bring two types of sulfur-containing nanomaterials including metallic sulfide nanomaterials and sulfur-containing quantum dots, to discuss and summarize the possibility and application as biosensors based on the sulfur-containing nanomaterials. Finally, future perspective and challenges of biosensors based on sulfur-containing nanomaterials are briefly rendered.