Design, Synthesis, and Application of Carbon Dots With Synergistic Antibacterial Activity

Abstract

The diversity of bacteria and their ability to acquire drug resistance lead to many challenges in traditional antibacterial methods. Photothermal therapies that convert light energy into localized physical heat to kill target microorganisms do not induce resistance and provide an alternative for antibacterial treatment. However, many photothermal materials cannot specifically target bacteria, which can lead to thermal damage to normal tissues, thus seriously affecting their biological applications. Here, we designed and synthesized bacteria-affinitive photothermal carbon dots (BAPTCDs) targeting MurD ligase that catalyzes the synthesis of peptidoglycan (PG) in bacteria. BAPTCDs presented specific recognition ability and excellent photothermal properties. BAPTCDs can bind to bacteria very tightly due to their chiral structure and inhibit enzyme activity by competing with D-glutamic acid to bind to MurD ligases, thus inhibiting the synthesis of bacterial walls. It also improves the accuracy of bacteria treatment by laser irradiation. Through the synergy of biochemical and physical effects, the material offers outstanding antibacterial effects and potentially contributes to tackling the spread of antibiotic resistance and facilitation of antibiotic stewardship.

Biogenic Synthesis of Fluorescent Carbon Dots (CDs) and Their Application in Bioimaging of Agricultural Crops

“…A simple and facile one-pot synthesis of the fluorescent CDs from orange waste peels was performed using the hydrothermal carbonization method at a mild temperature (180 °C). Likewise, in the present study, the biogenic synthesis of the CDs in the aqueous system results in a lesser yield, as mentioned in the results Section 3.1 , i.e., 83 mg per 1 g equating to nearly 8%, however, is more economical than other organic solvents like PEG (polyethylene glycol) used in the synthesis of CDs reported earlier in several studies [ 23 , 32 , 35 , 61 , 68 ]. The QY analysis demonstrated a lesser QY, that might be an attribute of larger CDs and a broad size distribution.…”

“…The presence of N-H stretches, and bends was confirmed in the FT-IR spectrum. Other reported studies on the quantum yield of the CDs derived from various precursors showed a vast range of QY from 7.8% [ 45 ] to 85% [ 23 , 46 , 58 ].…”

“…It was also found that the excitation wavelength for the CDs was between 270 nm and 370 nm, and the fluorescence peak for the CDs was between 420 nm and 500 nm. This indicated the emission of a blue or green fluorescence [ 23 , 72 , 73 ]. In the NTA, we observed individual nanoparticles in motion and their size distribution, which could be used to estimate the number of particles mL −1 in the solution.…”

“…There are several fluorescent nanomaterials (NMs) such as fluorescently doped silica and sol-gels [ 8 ], hydrophilic polymers (hydrogels) [ 9 , 10 ], semiconducting polymer dots [ 11 ], quantum dots, carbon dots [ 12 ], other carbonaceous nanomaterials, hydrophobic organic polymers [ 13 , 14 ], up-conversion NPs [ 15 ], various other nanomaterials like noble metal NPs (mainly gold and silver) [ 16 , 17 , 18 ], and dendrimers [ 19 ] that have been reported for their application in bioimaging [ 20 , 21 ]. Other applications of CDs include heavy metal sensing and antimicrobials [ 22 , 23 ]; antibiotic carriers; and fluorescent probes [ 24 ]. Despite all of their advantages, they are not without limitations.…”

Inorganic nanomaterials for intelligent photothermal antibacterial applications

“…At a small dose, it can effectively kill most E. coli and S. aureus within 5 min (Robby et al, 2021). Qie et al (2022) functionalized CQD with chiral biomolecules to prepare a bacterial affinity photothermal carbon point (BAPYCDs) for MurD ligase, and combined 808 nm 1.5 W cm −2 NIR laser with BAPYCDs. In 10 min, the BAPYCDs temperature of 200 μg ml −1 can be raised to 70.3 °C.…”