Role of surface charge in enhancing antibacterial activity of fluorescent carbon dots

Abstract

Herein, different surface charged carbon dots (Cdots) were synthesized by using diethylene glycol as a carbon source with various amine containing surface passivating agents. The synthesis method is very simple and fast microwave oven-based, that results in almost similar sized positive, negative and uncharged fluorescent Cdots which has been confirmed by zeta potential analysis in our case. The formation of Cdots was confirmed by characterization using fluorescence spectroscopy, transmission electron microscopy, XRD, FT-IR, and XPS spectroscopy. To find out relative bactericidal activity of these Cdots, green fluorescence protein expressing recombinant E. coli bacteria were taken as a model system. Time-dependent bacterial growth and FACS study demonstrated that both uncharged Cdots and positively charged Cdots were showing better bactericidal activity as compared to negative charged Cdots. The Cdots caused elevation of reactive oxygen species level, which is possibly leading to bacterial cell death.

Study on novel fluorescent carbon nanomaterials in food analysis

“…Heavy metal ions such as Hg 2+ , Au 3+ , Cr 6+ , Ag + , Fe 2+ , Cu 2+ , and Fe 3+, which are easily accumulated in animals and plants, are a significant factor that contributes to water or environmental a wide basic surface region, regardless of the form they are (Parra et al, 2020;Verma et al, 2020). Various studies on the synthesis and use of carbon quantum dots have been conducted in recent years.…”

Carbon Nanodots in Photodynamic Antimicrobial Therapy: A Review

“…Perhaps more important, however, is that both Gram-negative and -positive bacteria exhibit negative charges on their exterior cell walls, although these properties are different. The zeta potential subsequently provides an important indicator of potential cell/carbon dot electrostatic interactions and resulting APDT efficiency; in fact, a recent study by Verma et al demonstrates using zeta potential analysis that positive/neutrally-charged carbon dots exhibit higher antibacterial activity against Escherichia coli ( E. coli ) than dots carrying a negative potential [ 50 ]. Using this characterization technique, researchers may more effectively tune the surface passivation properties of their carbon dots for expanded applications.…”

Carbon Dots Fabrication: Ocular Imaging and Therapeutic Potential

“…This is facilitated by the small size and higher surface area-to-mass ratio of the NP (Wang et al, 2017). In addition, CDs with neutral or positive charges have a greater antibacterial efficacy than the negatively charged CDs due to the facilitated interactions with the negatively charged lipid membrane of bacterial cells (Verma et al, 2019). The generation of reactive oxygen species (ROS), as a bactericidal mechanism, is greater in uncharged versus positively charged CDs due to the difference in the availability of negatively charged functional groups (Verma et al, 2019).…”

“…In addition, CDs with neutral or positive charges have a greater antibacterial efficacy than the negatively charged CDs due to the facilitated interactions with the negatively charged lipid membrane of bacterial cells (Verma et al, 2019). The generation of reactive oxygen species (ROS), as a bactericidal mechanism, is greater in uncharged versus positively charged CDs due to the difference in the availability of negatively charged functional groups (Verma et al, 2019). For ophthalmic indications, CDs with a positive zeta potential has been shown to better cross the corneal epithelium, resulting in a high bioavailability, something atypical in traditional topical treatments (Jian et al, 2017).…”