Engineered Bright Blue- and Red-Emitting Carbon Dots Facilitate Synchronous Imaging and Inhibition of Bacterial and Cancer Cell Progression via ¹O₂-Mediated DNA Damage under Photoirradiation

Abstract

The development of biocompatible, widely applicable fluorescent imaging probe, with emission beyond the cellular and tissue autofluorescence interference, is a challenging task. In this regard, a series of 28 different fluorescent carbon dots (CDs) were synthesized using carbohydrates as carbon and cysteine (Cys) and o-phenylenediamine (OPD) as nitrogen source. The screened CDs showed photostability with bright blue (∼505–520 nm) and red (∼588–596 nm) emission and high fluorescence quantum yield (QY = 72.5 ± 4.5%). FTIR and NMR studies suggested presence of carboxylate and ester group for Cys- and OPD-based CDs, respectively. HRTEM results showed particle size of ∼3.3–5.8 nm for all the developed CDs. The antibacterial studies suggested that the developed CDs showed preferential antibacterial activity against Escherichia coli, with IC50 value of ∼200 μg/mL. Cytotoxicity and confocal microscopy studies of HeLa cells reflected that these CDs showed both anticancer activity and imaging ability. Agarose gel electrophoresis, together with SOSG assay and thiol estimation studies, suggested oxidative stress induced DNA degradation to be the primary cause for cell death. These hemocompatible CDs can thus be used as simultaneous imaging probe and photo dynamic therapeutic agent for both antibacterial and anticancer activity.

Nucleolus-Targeted Red Emissive Carbon Dots with Polarity-Sensitive and Excitation-Independent Fluorescence Emission: High-Resolution Cell Imaging and in Vivo Tracking

“…Fluorescent carbon dots (CDs), which are commonly synthesized via hydrothermal and solvothermal methods, − have found numerous applications in bioimaging, − drug delivery, , catalysis, − sensing, − light-emitting devices, , nanomaterial fabrication, , and cancer therapy − due to their characteristics including facile preparation, good biocompatibility, prominent optical properties, and proper surface chemistries. In particular, the red/near-infrared (NIR) emissive CDs have attracted tremendous attention due to their superior properties resulting from their long-wavelength emission, including large tissue penetration depths, low levels of light scattering/absorption, and negligible interference from the background autofluorescence of biological tissues. − To design and fabricate red emissive CDs, heteroatom (usually nitrogen and sulfur) doping has been adopted. − For instance, Jiang et al used three different phenylenediamine isomers to prepare red, green, and blue emissive nitrogen-doped CDs via a solvothermal route for full-color displays and cell imaging . Among them, the CDs made from p -phenylenediamine (pPDA) have red fluorescence emission and display a fluorescence quantum yield (QY) of 26.1% in ethanol solution.…”

Quaternized carbon quantum dots with broad-spectrum antibacterial activity for treatment of wounds infected with mixed bacteria

“…Compared with the reported representative antibacterial carbon nanomaterials (Supplementary Table 6) 6,24,30,33,42,[52][53][54][55] , the mechanism of antibacterial action of the as-synthesized CQDs in this work provided a new way of thinking for studying the antibacterial mechanism of CQDs with broad-spectrum antibacterial activities. This study provides a feasible basis for the research and development of new antibiotics and the application of CQDs in the eld of antibiotics.…”

Water soluble, red emitting, carbon nanoparticles stimulate 3D cell invasion via clathrin-mediated endocytic uptake

“…The number of peaks also shows the complex mixture of crystalline components in the sample solution of CNPs. 18 The peaks at 15.46˚ and 31.4˚ correspond to the precursor material PPDA, revealing some impurities are present due to incomplete carbonization of PPDA as shown in Figure 1e. 19 Raman spectroscopy was also used as a non-destructive way to understand the degree of graphitization of CNPs.…”