Abstract
Carbon dots (CDs) were obtained from medicinal turmeric leaves (Curcuma longa) by a facile one-step hydrothermal method and evaluated for their bactericidal activities against two gram-negative; Escherichia coli, Klebsiella pneumoniae, and two gram-positive counterparts; Staphylococcus aureus, S. epidermidis. The CDs exhibited spherical shapes with a mean size of 2.6 nm. The fluorescence spectra of CDs revealed intense fluorescence at λex/em = 362/429 nm with a bright blue color in an aqueous solution. The CDs showed strong photostability under various environmental conditions (pH, salt, and UV-radiation). The complete bactericidal potency of CDs was 0.25 mg/mL for E.coli and S. aureus after 8 h of exposure, while for K. pneumoniae, and S. epidermidis, the CDs at 0.5 mg/mL good antibacterial effect within 8 h and complete eradication after 24 h of exposure is observed. The release of reactive oxygen species played a crucial role in the death of the bacterial cell. The present study provides a strategy for the preparation of CDs from a medicinal plant and their potential antibacterial activities against four common contagious pathogens.
Highlights
Inspiring by the above biological properties, we extend their antibacterial properties by making Carbon dots (CDs) nanoparticles from turmeric (Curcuma longa) leaves by a one-step green synthetic pathway
The synthesized CDs exhibited the strongest emission at 429 nm with excitation at 362 nm (Figure 1c)
The CDs in aqueous solution appeared as a light yellow color under daylight (Figure 1c, inset), but exhibited bright blue luminescence when irradiated with UV light at
Summary
Luminescent carbon nanodots (CDs, C-dots) were accidentally discovered during the refining of single-walled carbon nanotubes in 2004 [1]. CDs, a new-fangled member of the carbon nanomaterials, have good chemical and photochemical stability together with biocompatibility without intrinsic toxicity. Their unprecedented and unique properties encompass tunable emission, optical properties, biocompatibility, nontoxic, superior quantum yield, water solubility, and up-conversion photoluminescent, etc. Turmeric (Curcuma longa L.) is a major herb mostly cultivated in Asia and widely used as a spice and coloring agent or food additive It has become a popular medicinal plant worldwide, curcumin is one of the major compounds in turmeric and it functions as a drug with antioxidant, anti-bacterial, anti-fungal, anti-parasitic, antiinflammatory, anti-mutagenic, anti-carcinogenic, and detox properties [39]. Their potential applications as an emerging antimicrobial agent against four common bacterial strains are reported in the current manuscript
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