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Keywords = chiral carbon dots

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17 pages, 6987 KiB  
Review
Colorimetric Visualization of Chirality: From Molecular Sensors to Hierarchical Extension
by Yuji Kubo
Molecules 2025, 30(8), 1748; https://doi.org/10.3390/molecules30081748 - 14 Apr 2025
Viewed by 630
Abstract
The optical sensing of chirality is widely used in many fields, such as pharmaceuticals, agriculture, food, and environmental materials. In this context, the color-based cascade amplification of chirality, coupled with chiral recognition for analytes, provides a low-cost and straightforward detection method that avoids [...] Read more.
The optical sensing of chirality is widely used in many fields, such as pharmaceuticals, agriculture, food, and environmental materials. In this context, the color-based cascade amplification of chirality, coupled with chiral recognition for analytes, provides a low-cost and straightforward detection method that avoids the use of expensive and sophisticated instrumentation. However, the realization of chiral detection using this approach is still challenging because the construction of a three-dimensional optical recognition site is required to easily discern differences in chirality. Therefore, considerable efforts have been dedicated to developing a hierarchical approach based on molecular organization to provide colorimetric sensors for chirality detection. This review covers function-integrated molecular sensors with colorimetric responsive sites based on absorption, fluorescence, and aggregation-induced emission enabled by molecular organization. In line with the hierarchical approach, data-driven chemometrics is a useful method for quantitative and accurate chiral pattern recognition. Finally, colorimetric nanomaterials are discussed, focusing on sensing platforms using noble-metal nanoparticles, carbon dots, and photonic crystal gels. Full article
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19 pages, 10301 KiB  
Article
Biocompatible Carbon Dots/Polyurethane Composites as Potential Agents for Combating Bacterial Biofilms: N-Doped Carbon Quantum Dots/Polyurethane and Gamma Ray-Modified Graphene Quantum Dots/Polyurethane Composites
by Zoran Marković, Sladjana Dorontić, Svetlana Jovanović, Janez Kovač, Dušan Milivojević, Dragana Marinković, Marija Mojsin and Biljana Todorović Marković
Pharmaceutics 2024, 16(12), 1565; https://doi.org/10.3390/pharmaceutics16121565 - 6 Dec 2024
Cited by 3 | Viewed by 1380
Abstract
Background: Pathogen bacteria appear and survive on various surfaces made of steel or glass. The existence of these bacteria in different forms causes significant problems in healthcare facilities and society. Therefore, the surface engineering of highly potent antimicrobial coatings is highly important in [...] Read more.
Background: Pathogen bacteria appear and survive on various surfaces made of steel or glass. The existence of these bacteria in different forms causes significant problems in healthcare facilities and society. Therefore, the surface engineering of highly potent antimicrobial coatings is highly important in the 21st century, a period that began with a series of epidemics. Methods: In this study, we prepared two types of photodynamic polyurethane-based composite films encapsulated by N-doped carbon quantum dots and graphene quantum dots irradiated by gamma rays at a dose of 50 kGy, respectively. Further, we investigated their structural, optical, antibacterial, antibiofouling and biocompatibility properties. Results: Nanoelectrical and nanomechanical microscopy measurements revealed deviations in the structure of these quantum dots and polyurethane films. The Young’s modulus of elasticity of the carbon and graphene quantum dots was several times lower than that for single-walled carbon nanotubes (SWCNTs) with chirality (6,5). The electrical properties of the carbon and graphene quantum dots were quite similar to those of the SWCNTs (6,5). The polyurethane films with carbon quantum dots were much more elastic and smoother than the films with graphene quantum dots. Antibacterial tests indicated excellent antibacterial activities of these films against a wide range of tested bacteria, whereas the antibiofouling activities of both composite films showed the best results against the Staphylococcus aureus and Escherichia coli biofilms. Biocompatibility studies showed that neither composite film exhibited any cytotoxicity or hemolysis. Conclusions: Obtained results indicate that these composite films could be used as antibacterial surfaces in the healthcare facilities. Full article
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23 pages, 11559 KiB  
Review
Carbon Dots in Enantioselective Sensing
by Martina Bortolami, Antonella Curulli, Paola Di Matteo, Rita Petrucci and Marta Feroci
Sensors 2024, 24(12), 3945; https://doi.org/10.3390/s24123945 - 18 Jun 2024
Cited by 3 | Viewed by 1887
Abstract
Chirality has a crucial effect on clinical, chemical and biological research since most bioactive compounds are chiral in the natural world. It is thus important to evaluate the enantiomeric ratio (or the enantiopurity) of the selected chiral analytes. To this purpose, fluorescence and [...] Read more.
Chirality has a crucial effect on clinical, chemical and biological research since most bioactive compounds are chiral in the natural world. It is thus important to evaluate the enantiomeric ratio (or the enantiopurity) of the selected chiral analytes. To this purpose, fluorescence and electrochemical sensors, in which a chiral modifier is present, are reported in the literature. In this review, fluorescence and electrochemical sensors for enantiorecognition, in which chiral carbon dots (CDs) are used, are reported. Chiral CDs are a novel zero-dimensional carbon-based nanomaterial with a graphitic or amorphous carbon core and a chiral surface. They are nanoparticles with a high surface-to-volume ratio and good conductivity. Moreover, they have the advantages of good biocompatibility, multi-color emission, good conductivity and easy surface functionalization. Their exploitation in enantioselective sensing is the object of this review, in which several examples of fluorescent and electrochemical sensors, containing chiral CDs, are analyzed and discussed. A brief introduction to the most common synthetic procedures of chiral CDs is also reported, evidencing strengths and weaknesses. Finally, consideration concerning the potential challenges and future opportunities for the application of chiral CDs to the enantioselective sensing world are outlined. Full article
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23 pages, 6113 KiB  
Article
A Novel Ambroxol-Derived Tetrahydroquinazoline with a Potency against SARS-CoV-2 Proteins
by Alena I. Krysantieva, Julia K. Voronina and Damir A. Safin
Int. J. Mol. Sci. 2023, 24(5), 4660; https://doi.org/10.3390/ijms24054660 - 28 Feb 2023
Cited by 16 | Viewed by 3194
Abstract
We report synthesis of a novel 1,2,3,4-tetrahydroquinazoline derivative, named 2-(6,8-dibromo-3-(4-hydroxycyclohexyl)-1,2,3,4-tetrahydroquinazolin-2-yl)phenol (1), which was obtained from the hydrochloride of 4-((2-amino-3,5-dibromobenzyl)amino)cyclohexan-1-ol (ambroxol hydrochloride) and salicylaldehyde in EtOH. The resulting compound was produced in the form of colorless crystals of the composition 1∙0.5EtOH. [...] Read more.
We report synthesis of a novel 1,2,3,4-tetrahydroquinazoline derivative, named 2-(6,8-dibromo-3-(4-hydroxycyclohexyl)-1,2,3,4-tetrahydroquinazolin-2-yl)phenol (1), which was obtained from the hydrochloride of 4-((2-amino-3,5-dibromobenzyl)amino)cyclohexan-1-ol (ambroxol hydrochloride) and salicylaldehyde in EtOH. The resulting compound was produced in the form of colorless crystals of the composition 1∙0.5EtOH. The formation of the single product was confirmed by the IR and 1H spectroscopy, single-crystal and powder X-ray diffraction, and elemental analysis. The molecule of 1 contains a chiral tertiary carbon of the 1,2,3,4-tetrahydropyrimidine fragment and the crystal structure of 1∙0.5EtOH is a racemate. Optical properties of 1∙0.5EtOH were revealed by UV-vis spectroscopy in MeOH and it was established that the compound absorbs exclusively in the UV region up to about 350 nm. 1∙0.5EtOH in MeOH exhibits dual emission and the emission spectra contains bands at about 340 and 446 nm upon excitation at 300 and 360 nm, respectively. The DFT calculations were performed to verify the structure as well as electronic and optical properties of 1. ADMET properties of the R-isomer of 1 were evaluated using the SwissADME, BOILED-Egg, and ProTox-II tools. As evidenced from the blue dot position in the BOILED-Egg plot, both human blood–brain barrier penetration and gastrointestinal absorption properties are positive with the positive PGP effect on the molecule. Molecular docking was applied to examine the influence of the structures of both R-isomer and S-isomer of 1 on a series of the SARS-CoV-2 proteins. According to the docking analysis results, both isomers of 1 were found to be active against all the applied SARS-CoV-2 proteins with the best binding affinities with Papain-like protease (PLpro) and nonstructural protein 3 (Nsp3_range 207–379-AMP). Ligand efficiency scores for both isomers of 1 inside the binding sites of the applied proteins were also revealed and compared with the initial ligands. Molecular dynamics simulations were also applied to evaluate the stability of complexes of both isomers with Papain-like protease (PLpro) and nonstructural protein 3 (Nsp3_range 207–379-AMP). The complex of the S-isomer with Papain-like protease (PLpro) was found to be highly unstable, while the other complexes are stable. Full article
(This article belongs to the Collection Feature Papers in Molecular Biophysics)
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15 pages, 3666 KiB  
Article
Electrochemical Bottom-Up Synthesis of Chiral Carbon Dots from L-Proline and Their Application as Nano-Organocatalysts in a Stereoselective Aldol Reaction
by Martina Bortolami, Ingrid Izabela Bogles, Cecilia Bombelli, Fabiana Pandolfi, Marta Feroci and Fabrizio Vetica
Molecules 2022, 27(16), 5150; https://doi.org/10.3390/molecules27165150 - 12 Aug 2022
Cited by 29 | Viewed by 4151
Abstract
Chirality is undoubtedly a fundamental property of nature since the different interactions of optically active molecules in a chiral environment are essential for numerous applications. Thus, in the field of asymmetric synthesis, the search for efficient, sustainable, cost-effective and recyclable chiral catalysts is [...] Read more.
Chirality is undoubtedly a fundamental property of nature since the different interactions of optically active molecules in a chiral environment are essential for numerous applications. Thus, in the field of asymmetric synthesis, the search for efficient, sustainable, cost-effective and recyclable chiral catalysts is still the main challenge in organic chemistry. The field of carbon dots (CDs) has experienced tremendous development in the last 15 years, including their applications as achiral catalysts. Thus, understanding the implications of chirality in CDs chemistry could be of utmost importance to achieving sustainable and biocompatible chiral nanocatalysts. An efficient and cost-effective electrochemical synthetic methodology for the synthesis of L-Proline-based chiral carbon dots (CCDs) and EtOH-derived L-Proline-based chiral carbon dots (CCDs) is herein reported. The electrochemical set-up and reaction conditions have been thoroughly optimised and their effects on CCDs size, photoluminescence, as well as catalytic activity have been investigated. The obtained CCDs have been successfully employed to catalyze an asymmetric aldol reaction, showing excellent results in terms of yield, diastereo- and enantioselectivity. Moreover, the sustainable nature of the CCDs was demonstrated by recycling the catalysts for up to 3 cycles without any loss of reactivity or stereoselectivity. Full article
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10 pages, 2313 KiB  
Communication
Bacterial Cellulose: A Versatile Chiral Host for Circularly Polarized Luminescence
by Chen Zou, Dan Qu, Haijing Jiang, Di Lu, Xiaoting Ma, Ziyi Zhao and Yan Xu
Molecules 2019, 24(6), 1008; https://doi.org/10.3390/molecules24061008 - 13 Mar 2019
Cited by 27 | Viewed by 5005
Abstract
Materials capable of circularly polarized luminescence (CPL) have attracted considerable attention for their promising potential applications. Bacterial cellulose (BC) was characterized as having a stable right-handed twist, which makes it a potential chiral host to endow luminophores with CPL. Then, the CPL-active BC [...] Read more.
Materials capable of circularly polarized luminescence (CPL) have attracted considerable attention for their promising potential applications. Bacterial cellulose (BC) was characterized as having a stable right-handed twist, which makes it a potential chiral host to endow luminophores with CPL. Then, the CPL-active BC composite film was constructed by simply impregnating bacterial cellulose pellicles with dilute aqueous solutions of luminophores (rhodamine B, carbon dots, polymer dots) and drying under ambient conditions. Simple encapsulation of luminophores renders BC with circularly polarized luminescence with a dissymmetry factor of up to 0.03. The multiple chiral centers of bacterial cellulose provide a primary asymmetric environment that can be further modulated by supramolecular chemistry, which is responsible for its circular polarization ability. We further demonstrate that commercial grade paper may endow luminophores with CPL activity, which reifies the universality of the method. Full article
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16 pages, 4078 KiB  
Article
Novel N-Doped Carbon Dots/β-Cyclodextrin Nanocomposites for Enantioselective Recognition of Tryptophan Enantiomers
by Qi Xiao, Shuangyan Lu, Chusheng Huang, Wei Su and Shan Huang
Sensors 2016, 16(11), 1874; https://doi.org/10.3390/s16111874 - 9 Nov 2016
Cited by 42 | Viewed by 8263
Abstract
Based on N-doped carbon dots/β-cyclodextrin nanocomposites modified glassy carbon electrodes (N-CDs/β-CD/GCE), an effective electrochemical sensor for enantioselective recognition of tryptophan (Trp) enantiomers was developed by differential pulse voltammograms (DPVs). Fluorescent N-CDs were synthesized through a hydrothermal method and characterized by spectroscopic approaches. The [...] Read more.
Based on N-doped carbon dots/β-cyclodextrin nanocomposites modified glassy carbon electrodes (N-CDs/β-CD/GCE), an effective electrochemical sensor for enantioselective recognition of tryptophan (Trp) enantiomers was developed by differential pulse voltammograms (DPVs). Fluorescent N-CDs were synthesized through a hydrothermal method and characterized by spectroscopic approaches. The N-CDs/β-CD nanocomposites were efficiently electrodeposited on the surface of GCE through C–N bond formation between N-CDs and electrode. The obtained N-CDs/β-CD/GCE was characterized by multispectroscopic and electrochemical methods. Such N-CDs/β-CD/GCE generated a significantly lower Ip and more negative Ep in the presence of l-Trp in DPVs, which was used for the enantioselective recognition of Trp enantiomers. The N-CDs/β-CD nanocomposites showed different binding constants for tryptophan enantiomers, and they further selectively bonded with l-Trp to form inclusion complexes. This N-CDs/β-CD/GCE combined advantages of N-CDs with strong C–N binding ability and β-CD with specific recognition of Trp enantiomers to fabricate a novel sensing platform for enantioselective recognition of Trp enantiomers. This strategy provided the possibility of using a nanostructured sensor to discriminate the chiral molecules in bio-electroanalytical applications. Full article
(This article belongs to the Special Issue Nanobiosensing for Sensors)
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