Interplay of structure and photophysics of individualized rod-shaped graphene quantum dots with up to 132 sp² carbon atoms

Sugar Cane (Saccharum officinarum L.) Waste Synthesized Si,N,S-Carbon Quantum Dots as High-Performance Corrosion Inhibitors for Mild Steel in Hydrochloric Acid

This work reports the obtention of Si,N,S-CQDs from sugar cane bagasse and their inhibitory action on the mild steel corrosion in 1 mol L-1 HCl solution. The CQDs were successfully obtained and characterized by X-ray photoelectron spectroscopy, Fourier-transform infrared spectroscopy, Dynamic light scattering, Raman, and UV-vis techniques, also showing endogenous self-doping. The anti-corrosive activity of CQDs was investigated by gravimetric tests, potentiodynamic polarization curves, electrochemical impedance measurements, atomic force microscopy, and scanning electron microscopy. The electrochemical results show that the CQDs present a predominant inhibitory action on the cathodic process, presenting inhibition efficiency of 82, 89, 91, and 94% for 15, 25, 50, and 100 ppm, respectively. Gravimetric tests varying temperature demonstrate that the inhibitor functions through physical adsorption and remains effective for up to 72 h, exhibiting corrosion efficiency of 80.2, 93.2, 96.3, and 97.8% at 15, 25, 50, and 100 ppm concentrations, respectively, after 72 h of immersion. Dynamic light scattering and zeta potential measurements indicate that agglomerations of CQDs play a crucial role in inhibiting corrosion. These results show an excellent alternative for using sugar cane bagasse to produce CQDs and its application as a corrosion inhibitor, valuing agricultural waste and simultaneously solving industry problems.

Harnessing the Potential of Graphene Quantum Dots for Multifunctional Biomedical Applications

The existing and emerging demand for materials for life and health has contributed to the cultivation and development of respective markets. Nevertheless, the current generation of biomedical materials has yet to fully satisfy the clinical requirements of the market, which is still in its relative infancy. Research and development in this area must be prioritized in light of the pivotal role of new life and health materials in the biological field. Among many life and health materials, GQDs, an emerging nanomaterial, exhibit considerable promise in the biomedical field, primarily due to their exceptional properties. Furthermore, the direct preparation and functionalization of GQDs have facilitated the development of specific functional composites based on GQDs. The biological applications of GQDs are undergoing rapid growth, which makes it necessary to publish a review article presenting the latest advances in this field. This review provides an overview of the significant advances in synthesizing GQDs, the techniques employed for structural characterizations, and the properties that have been elucidated. Furthermore, it presents recent findings on applying GQDs in antimicrobial, anticancer, biosensing, drug delivery, and bioimaging applications. Finally, it explores the potential of GQDs in biomedicine and biotechnology, highlighting the current challenges that remain to be addressed.

Future Paths in Cryogenic Single-Molecule Fluorescence Spectroscopy

In the last three decades, cryogenic single-molecule fluorescence spectroscopy has provided average-free understanding of the photophysics and of fundamental interactions at molecular scales. Furthermore, they propose original pathways and applications in the treatment and storage of quantum information. The ultranarrow lifetime-limited zero-phonon line acts as an excellent sensor to local perturbations caused either by intrinsic dynamical degrees of freedom, or by external perturbations, such as those caused by electric fields, elastic and acoustic deformations, or light-induced dynamics. Single aromatic hydrocarbon molecules, being sensitive to nanoscale probing at nanometer scales, are potential miniaturized platforms for integrated quantum photonics. In this Perspective, we look back at some of the past advances in cryogenic optical microscopy and propose some perspectives for future development.