cqds  (Molecular Dynamics Inc)

Journal: RSC Advances

Article Title: Green spectrofluorimetric determination of clemastine using nitrogen and phosphorus Co-doped carbon quantum dots with face-centered design optimization and sustainability assessment

doi: 10.1039/d6ra01896c

Figure Lengend Snippet: Physicochemical and optical characterization of nitrogen and phosphorus co-doped carbon quantum dots (N,P-CQDs). (A) Transmission electron microscopy image showing quasi-spherical morphology and uniform size distribution. (B) Fourier-transform infrared spectrum displaying characteristic functional groups including O–H/N–H stretching, C O stretching, and P O stretching vibrations, confirming successful nitrogen and phosphorus co-doping and surface functionalization. (C) UV-visible absorption spectrum showing characteristic absorption maximum attributed to n → π* transitions. (D) Fluorescence emission spectrum exhibiting bright blue luminescence with substantial Stokes shift between excitation and emission wavelengths.

Article Snippet: The N,P-CQDs were synthesized via a rapid, energy-efficient microwave approach, yielding nanoprobes with excellent quantum yield (47.2 ± 2.3%), uniform size distribution (3.2 ± 0.9 nm), and strong blue fluorescence emission.

Techniques: Transmission Assay, Electron Microscopy, Fourier Transform Infrared Spectroscopy, Functional Assay, Fluorescence

Journal: RSC Advances

Article Title: Green spectrofluorimetric determination of clemastine using nitrogen and phosphorus Co-doped carbon quantum dots with face-centered design optimization and sustainability assessment

doi: 10.1039/d6ra01896c

Figure Lengend Snippet: Fluorescence quenching mechanism and thermodynamic characterization of N,P-CQD-clemastine interaction. (A) Progressive fluorescence quenching of N,P-CQDs upon incremental addition of clemastine, demonstrating concentration-dependent quenching behavior. (B) Stern–Volmer plots at three temperatures showing linear relationships with temperature-dependent slopes for mechanism identification. (C) Modified Stern–Volmer plots for determination of association constants ( K a ) at different temperatures. (D) Van't Hoff plot (ln K a versus 1/ T ) for thermodynamic parameter calculation including enthalpy change (Δ H °) and entropy change (Δ S °).

Article Snippet: The N,P-CQDs were synthesized via a rapid, energy-efficient microwave approach, yielding nanoprobes with excellent quantum yield (47.2 ± 2.3%), uniform size distribution (3.2 ± 0.9 nm), and strong blue fluorescence emission.

Techniques: Fluorescence, Concentration Assay, Modification

Journal: RSC Advances

Article Title: Green spectrofluorimetric determination of clemastine using nitrogen and phosphorus Co-doped carbon quantum dots with face-centered design optimization and sustainability assessment

doi: 10.1039/d6ra01896c

Figure Lengend Snippet: Fluorescence quenching mechanism and thermodynamic characterization of N,P-CQD-clemastine interaction. (A) Progressive fluorescence quenching of N,P-CQDs upon incremental addition of clemastine, demonstrating concentration-dependent quenching behavior. (B) Stern–Volmer plots at three temperatures showing linear relationships with temperature-dependent slopes for mechanism identification. (C) Modified Stern–Volmer plots for determination of association constants ( K a ) at different temperatures. (D) Van't Hoff plot (ln K a versus 1/ T ) for thermodynamic parameter calculation including enthalpy change (Δ H °) and entropy change (Δ S °).

Article Snippet: As a preliminary control, clemastine alone (4.0 μg mL −1 ) exhibited negligible intrinsic fluorescence across the 375–625 nm emission range (Fig. S4), confirming that all observed quenching responses originate exclusively from the N,P-CQD nanoprobes.

Techniques: Fluorescence, Concentration Assay, Modification

Journal: RSC Advances

Article Title: Green spectrofluorimetric determination of clemastine using nitrogen and phosphorus Co-doped carbon quantum dots with face-centered design optimization and sustainability assessment

doi: 10.1039/d6ra01896c

Figure Lengend Snippet: Individual factor effect plots from face-centered central composite design showing the influence of experimental parameters on fluorescence quenching efficiency. (A) Effect of buffer pH on analytical response. (B) Effect of buffer volume on quenching behavior. (C) Effect of N,P-CQD concentration on fluorescence response. (D) Effect of incubation time on quenching kinetics, demonstrating rapid complex formation consistent with static quenching mechanism.

Article Snippet: As a preliminary control, clemastine alone (4.0 μg mL −1 ) exhibited negligible intrinsic fluorescence across the 375–625 nm emission range (Fig. S4), confirming that all observed quenching responses originate exclusively from the N,P-CQD nanoprobes.

Techniques: Fluorescence, Concentration Assay, Incubation

Journal: RSC Advances

Article Title: Green spectrofluorimetric determination of clemastine using nitrogen and phosphorus Co-doped carbon quantum dots with face-centered design optimization and sustainability assessment

doi: 10.1039/d6ra01896c

Figure Lengend Snippet: Two-dimensional interaction plots and three-dimensional response surface visualizations showing significant interaction effects identified by face-centered central composite design. (A) Two-dimensional interaction plot of pH-buffer volume interaction showing interaction curves at different factor levels. (B) Two-dimensional interaction plot of pH-N,P-CQD concentration interaction demonstrating pH-dependent optimal nanoprobe requirements. (C) Three-dimensional response surface of pH-buffer volume interaction providing spatial visualization of synergistic effects on fluorescence quenching efficiency. (D) Three-dimensional response surface of pH-N,P-CQD concentration interaction showing curvature and optimal response region. Color gradients (green to yellow to orange-red) represent fluorescence quenching efficiency ( F 0 / F ratio values), with warmer colors indicating higher analytical response.

Article Snippet: As a preliminary control, clemastine alone (4.0 μg mL −1 ) exhibited negligible intrinsic fluorescence across the 375–625 nm emission range (Fig. S4), confirming that all observed quenching responses originate exclusively from the N,P-CQD nanoprobes.

Techniques: Concentration Assay, Fluorescence

Journal: International Journal of Nanomedicine

Article Title: Dendrocin ZM1 Nanoconjugates with Carbon Quantum Dots: A ROS-Generating Platform for Combating Multidrug-Resistant Bacteria

doi: 10.2147/IJN.S565719

Figure Lengend Snippet: Hemolytic effect, cytotoxic effect, and stability of Dendrocin ZM1–CQDs. ( a ) Hemolytic activity of Dendrocin ZM1–CQDs on human red blood cells (RBCs) at increasing concentrations corresponding to 1×, 2×, and 4× MIC values. The conjugated form demonstrated significantly reduced hemolytic activity compared to Dendrocin ZM1 alone. ( b ) Cytotoxicity of Dendrocin ZM1–CQDs on HEK-293 cells at increasing concentrations (2–128 µg/mL). Cell death was determined after 24 h of exposure. The conjugated peptide exhibited lower toxicity compared to Dendrocin ZM1 alone, particularly at higher concentrations. Data represent mean ± SD of three independent replicates.

Article Snippet: CQDs, Carbon quantum dots; MDR, Multidrug-resistant; MIC, Minimum inhibitory concentration; ROS, Reactive oxygen species; AMPs, Antimicrobial peptides; ZnO, Zinc oxide; CuO, copper oxide; Ag, Silver; TiO 2 , Titanium oxide; NPs, Nanoparticles; FTIR, Fourier transform infrared spectroscopy; DLS, Dynamic light-scattering; PL, Photoluminescence; XPS, X-ray Photoelectron Spectroscopy; TEM, Transmission electron microscopy; RP-HPLC, Reverse phase-high performance liquid chromatography; MD, Molecular Dynamics; PBC, Periodic boundary conditions; LINCS, Linear Constraint Solver.

Techniques: Activity Assay

Journal: International Journal of Nanomedicine

Article Title: Dendrocin ZM1 Nanoconjugates with Carbon Quantum Dots: A ROS-Generating Platform for Combating Multidrug-Resistant Bacteria

doi: 10.2147/IJN.S565719

Figure Lengend Snippet: ROS generation kinetics and scavenger effects in S. aureus ATCC 25923 and E. coli ATCC 25922. ( a and b ) Time-dependent intracellular ROS levels in S. aureus and E. coli treated with Dendrocin ZM1–CQDs (2× MIC), Dendrocin ZM1, CQDs, or untreated controls, measured using DCFH-DA fluorescence. Dendrocin ZM1–CQDs induced a rapid and sustained ROS burst peaking at 30–45 min, with significantly higher fold-changes compared with all controls (**p < 0.001, two-way ANOVA with Tukey’s post-hoc test). ( c and d ) Effect of ROS scavengers (NAC, thiourea, catalase) on Dendrocin ZM1–CQDs induced ROS levels at 45 min. Pre-incubation with scavengers markedly reduced ROS production and restored bacterial viability in both S. aureus and E. coli (**p < 0.001 vs Dendrocin ZM1–CQDs), confirming the causal role of oxidative stress in antibacterial activity. Data are presented as mean ± SD from three independent experiments performed in triplicate.

Article Snippet: CQDs, Carbon quantum dots; MDR, Multidrug-resistant; MIC, Minimum inhibitory concentration; ROS, Reactive oxygen species; AMPs, Antimicrobial peptides; ZnO, Zinc oxide; CuO, copper oxide; Ag, Silver; TiO 2 , Titanium oxide; NPs, Nanoparticles; FTIR, Fourier transform infrared spectroscopy; DLS, Dynamic light-scattering; PL, Photoluminescence; XPS, X-ray Photoelectron Spectroscopy; TEM, Transmission electron microscopy; RP-HPLC, Reverse phase-high performance liquid chromatography; MD, Molecular Dynamics; PBC, Periodic boundary conditions; LINCS, Linear Constraint Solver.

Techniques: Fluorescence, Incubation, Activity Assay

Journal: International Journal of Molecular Sciences

Article Title: Functionalized Carbon Dots from Bio-Based Precursors as Promising Fluorescent Probes for Cancer Cell Imaging

doi: 10.3390/ijms262412185

Figure Lengend Snippet: General concept of application of CQDs for CTC detection (blood sample collection, blood incubation with fluorescent CQDs, and in vitro imaging using microscope with epifluorescence adapter).

Article Snippet: Transmission electron microscopy (TEM) images of the carbon quantum dots (CQDs) were acquired using a JEOL JEM 2100 transmission electron microscope (JEOL Ltd., Tokyo, Japan) with a magnification of 30,000×.

Techniques: Incubation, In Vitro, Imaging, Microscopy

Journal: International Journal of Molecular Sciences

Article Title: Functionalized Carbon Dots from Bio-Based Precursors as Promising Fluorescent Probes for Cancer Cell Imaging

doi: 10.3390/ijms262412185

Figure Lengend Snippet: TEM microphotograph of the CQDs-8 and CQDs-9 sample.

Article Snippet: Transmission electron microscopy (TEM) images of the carbon quantum dots (CQDs) were acquired using a JEOL JEM 2100 transmission electron microscope (JEOL Ltd., Tokyo, Japan) with a magnification of 30,000×.

Techniques: