A novel type of graphene-like quantum dots, synthesized by oxidation and cage-opening of C buckminsterfullerene, has been studied as a fluorescent and absorptive probe for heavy-metal ions. The lattice structure of such unfolded fullerene quantum dots (UFQDs) is distinct from that of graphene since it includes both carbon hexagons and pentagons. The basic optical properties, however, are similar to those of regular graphene oxide quantum dots. On the other hand, UFQDs behave quite differently in the presence of heavy-metal ions, in that multiple sensitivity to Cu, Pb and As(III) was observed through comparable quenching of the fluorescent emission and different variations of the transmittance spectrum. By dynamic light scattering measurements and transmission electron microscope (TEM) images we confirmed, for the first time in metal sensing, that this response is due to multiple complexation and subsequent aggregation of UFQDs. Nonetheless, the explanation of the distinct behaviour of transmittance in the presence of As(III) and the formation of precipitate with Pb require further studies. These differences, however, also make it possible to discriminate between the three metal ions in view of the implementation of a selective multiple sensor.
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http://dx.doi.org/10.3390/s17112614 | DOI Listing |
Langmuir
December 2024
Department of Chemistry, University of Washington, Seattle, Washington 98195, United States.
Circular dichroism (CD) spectroscopy has emerged as a potent tool for probing chiral small-molecule ligand exchange on natively achiral quantum dots (QDs). In this study, we report a novel approach to identifying QD-biomolecule interactions by inducing chirality in CdS QDs using thermoresponsive elastin-like polypeptides (ELPs) engineered with C-terminal cysteine residues. Our method is based on a versatile two-step ligand exchange process starting from monodisperse oleate-capped QDs in nonpolar media and proceeding through an easily accessed achiral glycine-capped QD intermediate.
View Article and Find Full Text PDFChem Biomed Imaging
December 2024
College of Chemistry and Materials Science, Jinan University, Guangzhou, Guangdong 510632, China.
The large-scale preparation of fluorescent nanomaterials with laboratory-relevant chemical and optical properties will greatly forward their consumer market applications; however, it still remains challenging. In this work, a universal strategy was developed for the rapid and large-scale synthesis of fluorescent sulfur quantum dots that recently has drawn great attention because of their unique optical characteristics. From the fact that empty 3d orbitals of sulfide species are able to bind with lone-pair π electrons of the heteroatomic groups, many amino-group containing compounds, such as amino acid and polyethylenimine molecules, were exploited to synthesize sulfur quantum dots.
View Article and Find Full Text PDFACS Appl Electron Mater
December 2024
Institute of Semiconductor and Solid State Physics, Johannes Kepler University Linz, Altenberger Straße 69, 4040, Linz, Austria.
Germanium (Ge), the next-in-line group-IV material, bears great potential to add functionality and performance to next-generation nanoelectronics and solid-state quantum transport based on silicon (Si) technology. Here, we investigate the direct epitaxial growth of two-dimensional high-quality crystalline Ge layers on Si deposited at ultralow growth temperatures ( = 100-350 °C) and pristine growth pressures (≲10 mbar). First, we show that a decreasing does not degrade the crystal quality of homoepitaxial Ge/Ge(001) by comparing the point defect density using positron annihilation lifetime spectroscopy.
View Article and Find Full Text PDFInt J Nanomedicine
December 2024
Shanxi Medical University School and Hospital of Stomatology; Shanxi Province Key Laboratory of Oral Diseases Prevention and New Materials, Taiyuan, Shanxi, 030001, People's Republic of China.
Purpose: During fixed orthodontic treatment, oral hygiene is difficult to ensure and can easily lead to an imbalance in the oral micro-ecological balance. In this study, based on the adhesive properties of polydopamine (PDA) and the good antimicrobial and remineralization properties of carboxymethyl chitosan (CMC) and xylitol (Xy), new nanocomposites with both antimicrobial and remineralization capabilities were prepared to coat on orthodontic brackets.
Methods: Composite carbon dots (CDs) were synthesized using carboxymethyl chitosan and xylitol, we characterized them and the antimicrobial properties of the CMC-Xy-CDs were investigated by co-cultivation with S.
Sci Rep
December 2024
Department of Urology, Urological Science Institute, Yonsei University College of Medicine, 50-1 Yonsei-Ro, Seodaemun-gu, Seoul, 03722, South Korea.
Carbon dots (CDs) are versatile nanomaterials that are considered ideal for application in bioimaging, drug delivery, sensing, and optoelectronics owing to their excellent photoluminescence, biocompatibility, and chemical stability features. Nitrogen doping enhances the fluorescence of CDs, alters their electronic properties, and improves their functional versatility. N-doped CDs can be synthesized via solvothermal treatment of carbon sources with nitrogen-rich precursors; however, systematic investigations of their synthesis mechanisms have been rarely reported.
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