Nitrogen (N)-doped arginine carbon dots (Arg CD) were successfully synthesized using arginine as the amine source and citric acid as the carbon source via a one-pot green synthesis microwave-assisted technique in 2 min. Ag and Cu nanoparticles (NP) were generated within N-doped Arg CDs as composite Arg-Ag CDs and Arg-Cu CDs to render enhanced antibacterial properties. TEM analysis revealed that Arg CDs are in graphitic structures with d spacing ranging from 0.5 nm to 10 nm. The minimum inhibition concentration (MIC) values of Arg CDs with 6.250 mg/mL were decreased by about 100-fold for Arg-Ag CDs and ten-fold for Arg-Cu CDs with 0.062 and 0.625 mg/mL MIC values against Staphylococcus aureus (S. aureus). The highest antibacterial susceptibility was observed for the Arg-Ag CD composite with 0.125 and 0.312 mg/mL minimum bactericidal concentration (MBC) values against Gram negative S. aureus and Gram positive Escherichia coli (E. coli) bacteria strains, respectively. It was found that the metal NPs within Arg CDs significantly increased the antibacterial properties of CDs making them available in the treatment of infections caused by different bacterial species. Furthermore, Arg-Ag CD and Arg-Cu CD composites were tested for Acetylcholinesterase (AChE, E.C. 3.1.1.7) that break down acetylcholine (ACh) into choline and acetic acid leading to the loss of ACh which plays an essential role as neurotransmitter in Alzheimer disease. It was found that Arg-Cu CDs inhibited 74.9 ± 0.8% and Arg-Ag CDs inhibited 52.1 ± 3.8% of AChE at a 1.82 mg/mL concentration versus no inhibition for Arg-CD. Moreover, the chelating activity of Arg-Cu CDs and Arg-Ag CDs were tested for Fe(II) and it was found that almost 100% chelating was attained at 116 μg composites versus no measurable chelation for bare Arg CDs, suggesting the potential neurodegenerative disease treatment properties of these composite CDs in the brain.

https://www.mdpi.com/2311-5629/6/3/58/pdf

Nitrogen-Doped Arginine Carbon Dots and Its Metal Nanoparticle Composites as Antibacterial Agent

Novel yellow solid-state fluorescent-emitting carbon dots with high quantum yield for white light-emitting diodes.

Exploring sensory systems from metal ion receptors enables the continuous development of ion sensing technologies. Herein we report the synthesis of carbon quantum dots (CQDs) from 5,10,15,20-tetrakis(4-sulfophenyl)porphyrin (TSPP) and additional carbon source, and its application in Cu2+ imaging and quantifying in living cells. The CQDs are synthesized via a hydrothermal method in a successive polymerization and carbonization process. Due to the surface traps introduced by TSPP residue, the CQDs are featured with dual-emissive property of green (505 nm) and red (682 nm) fluorescence. Moreover, the red-to-green fluorescence ratio is readily customizable by tuning the molar fraction of TSPP. Benefited from Cu2+ complexation induced red fluorescence quenching, the CQDs can be served as the ratiometric fluorescent nanosensor for Cu2+ detection with ultra-high sensitivity and excellent specificity. The nanosensor is demonstrated to linearly detect Cu2+ in the range of 0−50 nM, with an extremely low limit of detection (LOD) of 37 pM. More importantly, interference from other biological compositions, especially Fe3+, is successfully excluded via the site-selective coordination and specific electron transfer path. Based on the excellent analytical performance of the nanosensor, quantifying Cu2+ in living cells is realized according to the linear correlation between fluorescence ratio and intracellular Cu2+ content, which is parallelly detected by inductively coupled plasma mass spectrometry (ICP-MS). To demonstrate its practicality, the nanosensor is challenged to measure Cu2+ uptake kinetics for cell lines derived from different tissues.

Porphyrin derived dual-emissive carbon quantum dots: Customizable synthesis and application for intracellular Cu2+ quantification

Carbon dots (CDs) are versatile nanoparticles with great potential for biological and environmental applications. CDs have unique characteristics such as high photostability, low cytotoxicity, size below 10 nm, rapid synthesis, and easy functionalization. These nanoparticles are promising for the development of fluorescent probes and the inactivation of microorganisms, especially viruses. This review covers several topics involving CDs, including synthesis methods, precursors, characterization techniques, sensitivity mechanisms, fluorescence origin, functionalization, and an overview of applications as nanosensors and virucidal agents. In addition, for the first time an economic analysis of the production of CDs from biomass using the Activity-Based Costing method was suggested. Finally, the main advances, gaps and future directions regarding the CDs were carefully analyzed.

Are carbon dots effective for ion sensing and antiviral applications? A state-of-the-art description from synthesis methods to cost evaluation

Quasi-solid, bio-renewable supercapacitor with high specific capacitance and energy density based on rice electrolytes and rice straw-derived carbon dots as novel electrolyte additives

Orange-red, green, and blue fluorescence carbon dots for white light emitting diodes

The invention discloses high-temperature metal drawing powder with a function of in-situ film formation and a preparation method of the powder and belongs to the field of metal drawing and lubricatingmaterials. The high-temperature metal drawing powder with the function of in-situ film formation is prepared from components in parts by weight as follows: 10-50 parts of tall oil, 8-20 parts of emulsified oil, 5-15 parts of caustic soda powder, 5-10 parts of nano silica powder, 2-5 parts of a coalescing emulsion, 5-10 parts of low-melting-point micropowder, 10-25 parts of lubrication assisting filler, 5-20 parts of an extreme pressure agent and 1-5 parts of an anticorrosion and antirust agent. The prepared high-temperature metal drawing powder has high lubrication and very low frictional coefficient, can be widely applied to drawing treatment of various steel wires, metal plated wires and other materials; the high-temperature metal drawing powder has the function of in-situ film formation, so that the utilization efficiency is greatly improved, the high-temperature metal drawing powder is environment-friendly, non-toxic and easy to store; meanwhile, the high-temperature metal drawingpowder is easy to treat after use, has excellent anticorrosion performance, temperature-resistant and pressure-resistant, the metal drawing service life is effectively prolonged and wear and deterioration are prevented.

Hongbin Qiao

Papers

Orange-red, green, and blue fluorescence carbon dots for white light emitting diodes

High-temperature metal drawing powder with function of in-situ film formation and preparation method of powder