Cysteine-Derived Chiral Carbon Quantum Dots: A Fibrinolytic Activity Regulator for Plasmin to Target the Human Islet Amyloid Polypeptide for Type 2 Diabetes Mellitus

Inhibition and disaggregation effect of flavonoid-derived carbonized polymer dots on protein amyloid aggregation

In this research, four water-insoluble flavonoid compounds were utilized and reacted with arginine to prepare four carbonized polymer dots with good water-solubility in a hydrothermal reactor. Structural characterization demonstrated that the prepared carbonized polymer dots were classic core-shell structure. Effect of the prepared carbonized polymer dots on protein amyloid aggregation was further investigated using hen egg white lysozyme and human lysozyme as model protein in aqueous solution. All of the prepared carbonized polymer dots could retard the amyloid aggregation of hen egg white lysozyme and human lysozyme in a dose-depended manner. All measurements displayed that the inhibition ratio of luteolin-derived carbonized polymer dots (CPDs-1) was higher than that of the other three carbonized polymer dots under the same dosage. This result may be interpreted by the highest content of phenolic hydroxyl groups on the periphery. The inhibition ratio of CPDs-1 on hen egg white lysozyme and human lysozyme reached 88 % and 83 % at the concentration of 0.5 mg/mL, respectively. CPDs-1 also could disaggregate the formed mature amyloid fibrils into short aggregates.

Colloidal Chiral Carbon Dots: An Emerging System for Chiroptical Applications

Chiral CDots (c-CDots) not only inherit those merits from CDots but also exhibit chiral effects in optical, electric, and bio-properties. Therefore, c-CDots have received significant interest from a wide range of research communities including chemistry, physics, biology, and device engineers. They have already made decent progress in terms of synthesis, together with the exploration of their optical properties and applications. In this review, the chiroptical properties and chirality origin in extinction circular dichroism (ECD) and circularly polarized luminescence (CPL) of c-CDots is briefly discussed. Then, the synthetic strategies of c-CDots is summarized, including one-pot synthesis, post-functionalization of CDots with chiral ligands, and assembly of CDots into chiral architectures with soft chiral templates. Afterward, the chiral effects on the applications of c-CDots are elaborated. Research domains such as drug delivery, bio- or chemical sensing, regulation of enzyme-like catalysis, and others are covered. Finally, the perspective on the challenges associated with the synthetic strategies, understanding the origin of chirality, and potential applications is provided. This review not only discusses the latest developments of c-CDots but also helps toward a better understanding of the structure-property relationship along with their respective applications.

Carbon quantum dots of ginsenoside Rb1 for application in a mouse model of intracerebral Hemorrhage

After intracerebral hemorrhage (ICH) occurs, the overproduction of reactive oxygen species (ROS) and iron ion overload are the leading causes of secondary damage. Removing excess iron ions and ROS in the meningeal system can effectively alleviate the secondary damage after ICH. This study synthesized ginsenoside Rb1 carbon quantum dots (RBCQDs) using ginsenoside Rb1 and ethylenediamine via a hydrothermal method. RBCQDs exhibit potent capabilities in scavenging ABTS + free radicals and iron ions in solution. After intrathecal injection, the distribution of RBCQDs is predominantly localized in the subarachnoid space. RBCQDs can eliminate ROS and chelate iron ions within the meningeal system. Treatment with RBCQDs significantly improves blood flow in the meningeal system, effectively protecting dying neurons, improving neurological function, and providing a new therapeutic approach for the clinical treatment of ICH.

Chiral nanomaterial-based approaches for diagnosis and treatment of protein-aggregated neurodiseases: current status and future opportunities

Protein misfolding and its aggregation, known as amyloid aggregates (Aβ), are some of the major causes of more than 20 diseases such as Parkinson's disease, Alzheimer's disease, and type 2 diabetes. The process of Aβ formation involves an energy-driven oligomerization of Aβ monomers, leading to polymerization and eventual aggregation into fibrils. Aβ fibrils exhibit multilevel chirality arising from its amino acid residues and the arrangement of folded polypeptide chains; thus, a chirality-driven approach can be utilized for the detection and inhibition of Aβ fibrils. In this regard, chiral nanomaterials have recently opened new possibilities for various biomedical applications owing to their stereoselective interaction with biological systems. Leveraging this chirality-driven approach with chiral nanomaterials against protein-aggregated diseases could yield promising results, particularly in the early detection of Aβ forms and the inhibition of Aβ aggregate formation via specific and strong "chiral-chiral interaction." Despite the advantages, the development of advanced theranostic systems using chiral nanomaterials against protein-aggregated diseases has received limited attention so far because of considerably limited formulations for chiral nanomaterials and lack of information of their chiroptical behavior. This review aims to present the current status of chiral nanomaterials explored for detecting and inhibiting Aβ forms. This review covers the origin of chirality in amyloid fibrils and nanomaterials and different chiral detection methods; furthermore, different chiral nanosystems such as chiral plasmonic nanomaterials, chiral carbon-based nanomaterials, and chiral nanosurfaces, which have been used so far for different therapeutic applications against protein-aggregated diseases, are discussed in detail. The findings from this review may pave the way for the development of novel approaches using chiral nanomaterials to combat diseases resulting from protein misfolding and can further be extended to other disease forms.

Multi-component determination based on high quantum yield "on-off-on" carbon quantum dots sensor

The nitrogen(N)-sulfur(S)-sodium(Na(I)) co-doped carbon quantum dots (CQDs) were synthesized via a one-step hydrothermal method, which exhibited a remarkably high fluorescence quantum yield (24.58%) and exceptional optical properties. The fluorescence "on-off-on" sensor was constructed. The fluorescence of CQDs was rapidly quenched with Fe(III) and the fluorescence recovered by ascorbic acid (Asc) partially and arginine (Arg)/histidine (His) completely. The CQDs fluorescence sensor demonstrated rapid response, exceptional sensitivity, excellent stability, remarkable selectivity, and robust anti-interference performance, which was feasible to simultaneously determine the concentrations of multiple analytes in the sample with satisfactory recovery rates. The "on-off-on" fluorescence mechanism of CQDs was investigated, revealing the significant potential of carbon nano-functionalized materials in the field of drug detection through fluorescence sensing.

Nonlinear and Emissive {[MIII(CN)6]3-···Polyresorcinol} (M = Fe, Co, Cr) Cocrystals Exhibiting an Ultralow Frequency Raman Response

Optically active functional noncentrosymmetric architectures might be achieved through the combination of molecules with inscribed optical responses and species of dedicated tectonic character. Herein, we present the new series of noncentrosymmetric cocrystal salt solvates (PPh4)3[M(CN)6](L)n·msolv (M = Cr(III), Fe(III), Co(III); L = polyresorcinol coformers, multiple hydrogen bond donors: 3,3',5,5'-tetrahydroxy-1,19-biphenyl, DiR, n = 2, or 5'-(3,5-dihydroxyphenyl)-3,3″,5,5″-tetrahydroxy-1,19:3',1″-terphenyl, TriRB, n = 1) denoted as MDiR and MTriRB, respectively. The hydrogen-bonded subnetworks {[M(CN)6]3-;Ln}∞ of dmp, neb, or dia topology are formed through structural matching between building blocks within supramolecular cis-bis(chelate)-like {[M(CN)6]3-;(H2L)2(HL)2} or tris(chelate)-like {[M(CN)6]3-;(H2L)3} fragments. The quantum-chemical analysis demonstrates the mixed electrostatic and covalent character of these interactions, with their strength clearly enhanced due to the negative charge of the hydrogen bond acceptor metal complex. The corresponding interaction energy is also dependent on the geometry of the contact and size matching of its components, rotational degree of freedom and extent of the π-electron system of the coformer, and overall fit to the molecular surroundings. Symmetry of the crystal lattices is correlated with the local symmetry of coformers and {complex;(coformer)n} hydrogen-bonded motifs characterized by the absence of the inversion center and mirror plane. All compounds reveal second-harmonic generation activity and photoluminescence diversified by individual UV-vis spectral characteristics of the components, and interesting low-frequency Raman scattering spectra within the subterahertz spectroscopic domain. Vibrational (infrared/Raman), UV-vis electronic absorption (experimental and calculated), and 57Fe Mössbauer spectra together with electrospray ionization mass spectrometry (ESI-MS) data are provided for the complete description of our systems.

Green and Red Emissive N,O-Doped Chiral Carbon Dots Functionalized with l-Cysteine

Although chirality plays an important role in the natural world, it has also attracted much scientific attention in nanotechnology, in particular, spintronics and bioapplications. Chiral carbon dots (CDs) are promising nanoparticles for sensing and bioimaging since they are biocompatible, ecofriendly, and free from toxic elements. Herein, green and red emissive chiral CDs are fabricated via surface modification treatment of achiral CDs at room temperature. After modification with l-cysteine molecules, the treated CDs demonstrate an intense chiral signal in the region of 200-300 nm with a dissymmetry factor up to 2.3 × 10-4 and high photoluminescence quantum yields of 19% and 15% for green and red emission bands, respectively. These CDs preserve their chiral signal in different ion systems, such as those with pH changes or in the presence of metal ions, along with remarkably low cytotoxicity, making them potential candidates for use as photoluminescent labels for biological objects.

Preparation of Chiral Carbon Quantum Dots and its Application

Chiral carbon quantum dots (cCQDs) , as a new type of carbon nano-functional material with tunable emission wavelength, superior photostability, low toxicity, biocompatibility and chirality, are playing an increasingly important role in the fields of chemistry, biology and medicine. This paper reviews the preparation methods (one-step and two-step), optical properties (UV, fluorescence, chirality) and applications in chiral catalysis, chiral recognition, targeted imaging as well as other fields, while lists some of the issues and challenges in the research of chiral carbon quantum dots. Finally, due to its good fluorescence and other properties, it is expected that chiral carbon quantum dots will have broad commercial prospects in future applications.

One-step hydrothermal preparation of chiral carbon quantum dots and enantioselective sensing of glutamine enantiomeric isomers

A novel method for chiral identification of glutamine enantiomers based on chiral carbon quantum dots (cCQDs) fluorescent probes. cCQDs were prepared using a one-step hydrothermal method with L-tryptophan as the carbon source and chiral source, producing spherical nanoparticles exhibiting a blue colour luminescence. The fluorescence intensity (F) of cCQDs was enhanced or quenched following the addition of chiral enantiomeric glutamine (L/D-Gln), and therefore cCQDs, as a fluorescence probe, could be used for enantioselective sensing of the L/D-Gln. The fluorescence enhancement value (∆FE ) exhibited good linearity with L-Gln concentration in the range 0.23-10.00 mM, and the limit of detection was 0.14 mM. The fluorescence quenching value (∆FQ ) showed a good linear relationship with D-Gln concentration in the range 0.29-10.00 mM, and the detection limit was 0.18 mM. The mechanism of fluorescence enhancement/quenching was explored by molecular modelling and the type of quenching. The method was applied to the determination of L-Gln content in real samples, and the recovery rate was satisfactory. This study provided a novel approach for the synthesis of cCQDs and the recognition of amino acid enantiomers.

Chiral Carbon Dots and Chiral Carbon Dots with Circularly Polarized Luminescence: Synthesis, Mechanistic Investigation and Applications

Chiral carbon dots (CCDs) can be widely used in various fields such as chiral recognition, chiral catalysis and biomedicine because of their unique optical properties, low toxicity and good biocompatibility. In addition, CCDs with circularly polarized luminescence (CPL) can be synthesized, thus broadening the prospects of CCDs applications. Since the research on CCDs is still in its infancy, this paper reviews the chiral origin, formation mechanism, chiral evolution, synthesis and emerging applications of CCDs, with a special focus on CCDs with CPL activity. It is hoped that it will provide some reference to solve the current problems faced by CCDs. Finally, the opportunities and challenges of the current research on CCDs are described, and their future development trends have also been prospected.

Recent Progress on Chiral Carbon Dots: Synthetic Strategies and Biomedical Applications

The discovery of chiral carbon dots (Ch-CDs) has opened up an exciting new research direction in the field of carbon dots. It not only retains the chirality of the precursor and exhibits highly symmetric chiral optical properties but also has properties such as chemical stability, antibacterial and antitumor properties, and good biocompatibility of carbon dots. Based on these advantages, the application of Ch-CDs in the biomedical field has attracted significant interest among researchers. However, a comprehensive review of the selection of precursors for Ch-CDs, preparation methods, and applications in biomedical fields is still lacking. Here, we summarize their precursor selection and preparation methods based on recent reports on Ch-CDs and provide the first comprehensive review for specific applications in biomedical engineering, such as biosensing, bioimaging, drug carriers, antibacterial and antibiofilm, and enzyme activity modulation. Finally, we discuss application prospects and challenges that need to be overcome. We hope this review will provide valuable guidance for researchers to prepare novel Ch-CDs and facilitate their application in biomedical engineering.