Electroluminescence and Photocatalytic Hydrogen Evolution of S,N Co-doped Graphene Oxide Quantum Dots

A facile hydrothermal route to synthesize S,N co-doped graphene oxide quantum dots (S,N-GOQDs) with stable electroluminescence, photoluminescence, and photocatalytic properties was demonstrated. The synthesized S,N-GOQDs show high yield and excitation–independent...

Enhancing chlorine resistance in polyamide membranes with surface & structure modification strategies

Higher efficient reverse osmosis (RO) membrane development is a significant issue due to the payoff among salt rejection and water flux and permissive chlorine attacking and fouling potential. Weak chlorine resistance is a distinctive challenge for composite polyamide thin-film reverse osmosis membranes. A commercial aromatic membrane was modified by grafting nitrogen-doped graphene oxide quantum dots (N-GOQDs) to enhance chlorine resistance, embedding two-dimensional MXene Ti3C2Tx, introducing synthetically reductive thioether units and oxidized graphitic carbon nitride (OGCN). In this work, salt rejection, chlorine resistance, and water flux increased compared to the pristine membrane. Comprehensive arrangement of desalination performance and chlorine resistance achieved by varying time and concentrations of prepared chemicals. For instance, improved chlorine resistance, after 12 hours of grafting time by N-GOQDs dopped membrane was 32.8%, after 6 hours of exposure time by MXene Ti3C2Tx membrane was 27.4%, after 1 hour of exposure time by thioether membrane was 28.1% and after 40 hours of doping time by OGCN membrane was 31.3%. N-GOQDs dopped membrane showed a good chlorine resistant property, but on the other hand, thioether nano units showed other properties more effectively, including water flux, salt rejection, and less reaction time.

Detection of Heavy Metals in Water Using Graphene Oxide Quantum Dots: An Experimental and Theoretical Study

In this work, we investigate by ab initio calculations and optical experiments the sensitivity of graphene quantum dots in their use as devices to measure the presence, and concentration, of heavy metals in water. We demonstrate that the quenching or enhancement in the optical response (absorption, emission) depends on the metallic ion considered. In particular, two cases of opposite behaviour are considered in detail: Cd2+, where we observe an increase in the emission optical response for increasing concentration, and Pb2+ whose emission spectra, vice versa, are quenched along the concentration rise. The experimental trends reported comply nicely with the different hydration patterns suggested by the models that are also capable of reproducing the minor quenching/enhancing effects observed in other ions. We envisage that quantum dots of graphene may be routinely used as cheap detectors to measure the degree of poisoning ions in water.

Synthesis of Nanocrystalline Reduced Graphene Oxide Quantum Dots

Reduced graphene oxide quantum dots (rGOQDTs) play a vital role in a variety of biological, optoelectronics, and environmental applications. The quality of 0D nanodots is compromised when they are cut from big 2D nanosheets. As a result, it is necessary to maintain a balance between quality and yield. Here, we developed a two-step hydrothermal process for producing nanocrystalline rGOQDTs by employing graphene oxide (GO) as an initial precursor. UV-Visible spectroscopy was used to explore the optical properties of rGOQDTs. XRD, Raman, and FTIR spectroscopic experiments were performed to better understand the crystalline and chemical properties and composition of rGOQDTs. The nanocrystalline rGOQDTs have an average crystallite size of 1.67[Formula: see text]nm. Using GO as an initial precursor implies a simple two-step approach for producing nanocrystalline rGOQDTs in a low-cost, highly efficient, and scalable manner.

Integrated mRNA and microRNA transcriptomic analysis reveals the common and individual responses of zebrafish embryos exposed to four types of graphene quantum dots (GQDs)

Background: Graphene quantum dots (GQDs) have great potential for bioimaging, biosensor, drug carrier, theranostics, and are recently reported as therapeutic agents to treat amylosis and inflammation. Most types of GQDs have proven low toxicity in previous studies, but data about the transcriptomic responses of in vivo systems exposed to various GQDs remains largely unknown. Results: We examined the mRNA and microRNA (miRNA) expression changes of zebrafish embryos exposed to four types of GQDs at a safe concentration (100 µg/mL), respectively as raw graphene quantum dots (R-GQDs), graphene oxide quantum dots (GOQDs), carboxyl GQDs (C-GQDs), and aminated GQDs (A-GQDs). The four GQDs elicited the number of differentially expressed genes (DEGs) in a decreasing order of A-GQDs, GOQDs, C-GQDs and R-GQDs to act on protein folding, potassium (K+) and calcium (Ca2+) channels, and spliceosome to varying degrees. Among the four GQDs, A-GQDs caused more genotoxic effects associated with lipid and hormone metabolism, MAPK signaling pathway, complement system, and ferropotosis. miRNA-seq data revealed that GOQDs aroused more differentially expressed miRNAs (DEMs), far exceed the total number of DEMs induced by the other three GQDs. dre-miR-735-5p and its potentially interactive gene-myogenin (myog) were identified as the only negatively-correlated miRNA-target gene pair shared by the four GQDs treatments. Conclusion: Taken together, this study provided substantial data underlying the common and specific transcriptomic responses of in vivo systems exposed to various types of GQDs, and also indicated the potential medicinal values of GQDs for ion antagonists and spliceosome-targeted therapies.