Screening of Chitosan Derivatives-Carbon Dots Based on Antibacterial Activity and Application in Anti-Staphylococcus aureus Biofilm

Abstract

Introduction Pathogenic bacteria, especially the ones with highly organized, systematic aggregating bacteria biofilm, would cause great harm to human health. The development of highly efficient antibacterial and antibiofilm functional fluorescent nanomaterial would be of great significance. Methods This paper reports the preparation of a series of antibacterial functional carbon dots (CDs) with chitosan (CS) and its derivatives as raw materials through one-step route, and the impact of various experiment parameters upon the optical properties and the antibacterial abilities have been explored, including the structures of the raw materials, excipients, and solvents. Results The CDs prepared by quaternary ammonium salt of chitosan (QCS) and ethylenediamine (EDA) exhibit multiple antibacterial effects through membrane breaking, DNA and protein destroying, and the production of singlet oxygen. The CDs showed excellent broad-spectrum inhibitory activity against a variety of bacteria (Gram-positive and negative bacteria), in particular, to the biofilm of Staphylococcus aureus with minimum inhibitory concentration at 10 µg/mL, showing great potential in killing bacteria and biofilms. The biocompatibility experiments proved that QCS-EDA-CDs are non-toxic to human normal hepatocytes and have low haemolytic effect. Furthermore, the prepared QCS-EDA-CDs have been successfully used in bacterial and biofilm imaging thanks to their excellent optical properties. Conclusion This paper explored the preparation and application of functional CDs, which can be used as the visual probe and therapeutic agents in the treatment of infections caused by bacteria and biofilm.

Quaternary Ammonium Salts: Insights into Synthesis and New Directions in Antibacterial Applications

“…The abovementioned analysis shows that the main reason for bacterial resistance is that the action mechanism of antibiotics is targeted, but the bactericidal mechanism of QASs is completely different from that of antibiotics, and there is no targeting effect. Therefore, the probability of bacterial resistance is greatly reduced by QASs compared with antibiotics, and they can be regarded as a promising substitute for antibiotics …”

“…Therefore, the probability of bacterial resistance is greatly reduced by QASs compared with antibiotics, and they can be regarded as a promising substitute for antibiotics. 175…”

Synthesis, properties and mechanism of carbon dots-based nano-antibacterial materials

“…Zhao et al, utilized chitosan-chitosan quaternary ammonium salts and ethylenediamine (EDA) as raw materials to prepare antibacterial functionalized CDs using a onestep hydrothermal process. These CDs demonstrated excellent broad-spectrum inhibitory activity against a variety of bacteria, especially S. aureus biofilms, as well as potent antibacterial and antibiofilm activity [56].…”

“…Zhao et al, prepared CDs from chitosan (CS) and its derivatives [carboxymethyl chitosan (CMCs) and oligo-chitosan quaternary ammonium salts (QCS)] to investigate the effect of carbon source domains on the antibacterial activity of the prepared products. QCS-CD was selected as a target for additional antibacterial research due to its superior water solubility and enhanced antibacterial activity compared to other prepared CDs [56]. Many cheap, renewable, and multi-component biomass precursors, such as figs [51], garlic [57], Artemisia argyi leaves, [58] pomegranate peel [59] and Panax ginseng Meyer [60], contain vitamins, amino acids, proteins, aromatic and phenolic substances.…”

Antibacterial and antibiofilm mechanisms of carbon dots: a review

“…The results showed that they could destroy the mature biofilms of S. aureus and E. coli in a short time and the removal effect appears to be dose dependent. Zhao et al 99 prepared a series of QCS-EDA-CDs using chitosan and its derivatives as precursors with excellent broad-spectrum inhibitory activity against bacterial biofilm formation, especially to S. aureus with a minimum inhibitory concentration of 10 μg mL −1 . The QCS-EDA-CDs achieve their antimicrobial activity by disrupting the cell membrane and decomposing EPS.…”