Broad-Spectrum Antibacterial Activity of Synthesized Carbon Nanodots from d-Glucose

Abstract

Carbon nanodots, a class of carbon nano-allotropes, have been synthesized through different routes and methods from a wide range of precursors. The selected precursor, synthetic method, and conditions can strongly alter the physicochemical properties of the resulting material and their intended applications. Herein, carbon nanodots (CNDs) have been synthesized from d-glucose by combining pyrolysis and chemical oxidation methods. The effect of the pyrolysis temperature, equivalents of oxidizing agent, and refluxing time were studied on the product and quantum yield. In the optimum conditions (pyrolysis temperature of 300 °C, 4.41 equiv of H2O2, 90 min of reflux) CNDs were obtained with 40% and 3.6% of product and quantum yields, respectively. The obtained CNDs are negatively charged (ζ-potential = −32 mV), excellently dispersed in water, with average diameter of 2.2 nm. Furthermore, ammonium hydroxide (NH4OH) was introduced as dehydrating and/or passivation agent during CNDs synthesis resulting in significant improvement of both product and quantum yields of about 1.5 and 3.76-fold, respectively. The synthesized CNDs showed a broad spectrum of antibacterial activities toward different Gram-positive and Gram-negative bacteria strains. Both synthesized CNDs caused highly colony forming unit reduction (CFU), ranging from 98% to 99.99% for most of the tested bacterial strains. However, CNDs synthesized in the absence of NH4OH, due to a negatively charged surface enriched in oxygenated groups, performed better in zone inhibition and minimum inhibitory concentration. The elevated antibacterial activity of high-oxygen-containing carbon nanodots is directly correlated to their ROS formation ability.

Surface and bulk defect formation during hydrothermal synthesis of LiCoPO4 crystals and their electrochemical implications

“…2(e)) was fitted with multiple peaks at different binding energies: sp 2 C–C at 284.48 eV, sp 3 C–C at 285.48 eV, C–O group at 286.38 eV, and OC–O group at 289.08 eV, respectively. 68–70 By comparing the relative atomic ratios of sp 2 (88.92%) and sp 3 (11.02%), sp 2 representing C–C bonding is found to be dominant in the carbon layer on HT-PM-C-LCP over sp 3 , which indicates C–H bonding. The XPS result is consistent with the I D / I G in Raman analysis.…”

Green synthesis of fluorescent carbon nanodots from sage leaves for selective anticancer activity on 2D liver cancer cells and 3D multicellular tumor spheroids

“…83 Due to its abundance in cancer cells it can be used as an indicator of the cellular oxidative stress generated by carbon nanomaterials. 36,79 Herein, we utilized Ellman's assay to evaluate the percentage of glutathione activity loss (GSH%) upon incubation with the synthesized CNDs. 84 As can be observed in Fig.…”

“…CNDs have been synthesized from various resources, such as man-made 28–31 and natural resources, 32–36 and they have also been synthesized from various herbs and plants and have been used in different biomedical applications. 37,38…”

“…17 In "bottom-up", methods such as microwaveassisted polymerization, pyrolysis, [18][19][20][21][22][23] hydrothermal/solvothermal, 24 and carbonization are used to convert small organic molecules contained in the precursor to carbon nanodots. [25][26][27] CNDs have been synthesized from various resources, such as man-made [28][29][30][31] and natural resources, [32][33][34][35][36] and they have also been synthesized from various herbs and plants and have been used in different biomedical applications. 37,38 One of the reasons that make CNDs good candidates for medical applications, especially as an anticancer agent, is their properties that caught and attracted the researcher's attention such as biocompatibility, 39 water dispersibility, 40 cytotoxicity, 41 good conductivity, 42 quantum yield and small size, 43 and uorescence emission.…”

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

“…The key is that the design of nanostructures confers unique functions and properties on NP. As depicted in figure 1, metal nanoparticles (MNPs) [8,9], metal oxide nanoparticles (MONPs) [10,11], and inorganic non-metallic NPs [12][13][14], constitute the majority of NPs with antibacterial effects at present. These nanomaterials have large specific surface areas and can interact with microorganisms through multivalent interactions.…”