Green fluorescent carbon dots as targeting probes for LED‐dependent bacterial killing

Abstract

The emergence of antimicrobial resistance (AMR) represents a significant health and economic challenge worldwide. The slow pace of antibacterial discovery necessitates strategies for optimal use of existing agents, including effective diagnostics able to drive informed prescribing; and development of alternative therapeutic strategies that go beyond traditional small-molecule approaches. Thus, the development of novel probes able to target bacteria for detection and killing, and that can pave the way to effective theranostic strategies, is of great importance.Here we demonstrate that metal-free green-emitting fluorescent carbon dots (FCDs) synthesized from glucosamine⋅HCl and m-phenylenediamine, and featuring 2,5-deoxyfructosazine on a robust amorphous core, can label both Grampositive (Staphylococcus aureus) and Gram-negative (Escherichia coli, Klebsiella pneumoniae, Pseudomonas aeruginosa) bacterial pathogens within 10 minutes of exposure. Moreover, effective killing of Gram-positive and -negative bacteria can be induced by combining FCD treatment with irradiation by LED light in the visible range. Cell-based, electron microscopy and tandem mass tag (TMT) proteomic experiments indicate that FCD administration in combination with LED exposure gives rise to local heating, ROS production, and membrane-and DNA-damage, suggesting multiple routes to FCD-mediated bacterial killing. Our data identify FCDs as materials that combine facile synthesis from low-cost precursors with labeling and light-dependent killing of clinically important bacterial species, and that thus warrant further exploration as the potential bases for novel theranostics.

Carbon dots: Types, preparation, and their boosted antibacterial activity by photoactivation. Current status and future perspectives

“…Likewise, in the research of Samphire et al (2022), green‐emitting fluorescent CDs were synthesized by microwave‐assisted route, and their antibacterial ability was evaluated against Escherichia coli and Staphylococcus aureus . The authors photoactivated the CDs (200 μg mL −1 ) with blue‐light‐emitting diodes (460 nm), demonstrating a complete bacterium killing after 4 hours of irradiation, but previously, after just 1.5 h of phototreatment, significant bacteria destruction was observed (>95%).…”

Biofilm Inhibition on Medical Devices and Implants Using Carbon Dots: An Updated Review

“…Irradiation of the CDs activated them with the generation of ROS species that effectively killed bacterial cells at a concentration of merely 200 μg/mL. The CDs served as excellent labeling agents due to their green fluorescent nature which did not interfere with the microbial autofluorescence emission . CDs prepared from vitamin C precursor electrochemically were studied for bactericidal activity against S. aureus , B. subtilis , and E. coli .…”

Carbon-based glyco-nanoplatforms: towards the next generation of glycan-based multivalent probes

“…CDs have emerged as a promising class of nanomaterials for the detection and inactivation of different bacterial species, the general bacteriostatic or bactericidal activity of CDs is attributed to physical bacterial membrane damage, cell wall destruction, inactivation via PTT and direct or light promoted generation of ROS, and DNA and protein damage through the PDT. 142,143 The specific interaction between the carbohydrate receptor expressed on the surface of bacterial cells and glycan-coated CDs represent a strategic opportunity to enhance the interaction and specificity of CDs with bacteria. Lai et al 144 reported an improved synthetic approach for the preparation of mannose-CDs to interact with the FimH mannose binding lectin present on E. coli cell surface.…”

“…CDs have emerged as a promising class of nanomaterials for the detection and inactivation of different bacterial species, the general bacteriostatic or bactericidal activity of CDs is attributed to physical bacterial membrane damage, cell wall destruction, inactivation via PTT and direct or light promoted generation of ROS, and DNA and protein damage through the PDT. 142,143…”