One‐Step Synthesis of Fluorescent Carbon Dots for Bio‐Labeling Assay

Abstract

Luminescent carbon dots, a newcomer in the domain of nanolights and nanomaterials have been studied extensively since past few years due to their fascinating properties of sensor design, biocompatibility, cell tracking, or fluorescence based live cell assays, medical diagnosis, photocatalysts, and also being potential building blocks for nanodevices. In this study, one‐pot green synthesis of water dispersible fluorescent carbon dots have been synthesized by using roasted gram shells. The structural and optical properties of the as‐prepared carbon dots are characterized by TEM, FTIR, UV‐vis absorption, photoluminescence spectra. The carbon dots showed greenish blue fluorescence under UV irradiation, excitation dependent emission, upconverted emission, high pH tolerance, and good biocompatibility. The carbon dots labeled Escherichia coli (E. coli) unveiled multicolor emission behavior under different excitation wavelength. These carbon dots showed their superiority with respect to commercially available synthetic dyes which have severe limitations including photobleaching effect, high cost, etc. The incorporation of carbon dots in the bacterial culture medium does not show any kind of growth delay of the bacterium up to 400 mg mL−1. The goal is to establish this carbon dots in bio‐labeling assay with its physicochemical features (small particle size, high luminescence efficiency, good biocompatibility, low toxicity) against various environments such as wide range of pH, high ionic medium. Concisely, this work bestows an innovative aspect to the commercialization of carbon dots as a potent alternative to synthetic organic dyes for multicolor emitting probes for cell‐labeling gram negative bacteria E. coli.

Carbon Dots for Heavy-Metal Sensing, pH-Sensitive Cargo Delivery, and Antibacterial Applications

“…This excitation-dependent emission behavior was in accordance with previous reports, which occurred because of the surface-emissive trap and size effect influencing the band gap of CDs. 27,50 The fluorescence emission spectra of JB-CDs were found to be dependent on the concentration. It was clearly observed from Figure 3d that the fluorescent signal first increased with increasing concentration (up to 50−100 mg/100 mL) and later (300−700 mg/ 100 mL) a decreased signal was obtained at high concentrations.…”

Dansyl-modified carbon dots with dual-emission for pH sensing, Fe3+ ion detection and fluorescent ink

“…1d. The three absorption peaks at 210 nm, 242 nm and 310 nm were ascribed to the p-p* transition of the C]C bond, the p-p* transition of aromatic sp 2 hybridization, and n-p* transition of the C]O bond, 44,45 respectively. CSCDs (red) had two absorption peaks at 210 nm and 310 nm.…”

Microwave-Synthesized Polysaccharide-Derived Carbon Dots as Therapeutic Cargoes and Toughening Agents for Elastomeric Gels

“…The bottom-up approach is a chemical method by virtue of which molecular precursors are getting covalently coupled to each other, resulting in fluorescent CDs. Some bottom-up approaches include pyrolysis, oxidation, dehydration, and microwave irradiation. − There are many biopolymers like hemicellulose, lignin, chitosan, and other polysaccharides that were used as primary precursor materials for CD synthesis . However, due to the high carbon content, these CDs show hydrophobicity that restricts the application of this material in aqueous systems .…”