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

Abstract

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.

Chondroitin Sulfate-Based Cryogels for Biomedical Applications

“…Fe(II) cheating activity was carried out according to the literature [ 50 ]. A sample solution in DI water in 31.25–1000 µg/mL concentration with a 140 µL volume was put into a 96-well plate.…”

Coumarin-Modified CQDs for Biomedical Applications—Two-Step Synthesis and Characterization

“…The obtained nanomaterials were studied over their fluorescence properties (Figure 8). It is well-known that all carbon dots potentially exhibit very good or excellent luminescent behaviors which depend on the QD type [3][4][5][6][7][8][9][10][11]. PL spectra of the prepared CQDs show that all samples are promising candidates for biomedical optical-based applications.…”

“…Such methods are also often associated with long shelf life of the products. However, not all substances are good candidates for biosensors since some of them may exhibit photobleaching or photoblinking in time which is an undesirable feature [3][4][5][6][7]. In addition, they cannot be used for multicolor detection due to the overlapping emission lines [8].…”

“…One of the most interesting classes of nanomaterials are quantum dots (QDs) defined as particles of size below 10 nm [3]. Importantly, they exhibit some very attractive features like high fluorescence intensity dependable on the excitation wavelength [3][4][5][6][7]. This unique property is related mostly to various quantum effects [9].…”

Poli(Rutin) micro/nanogels for biomedical applications

“…Fe (II) chelating activity was studied according to the literature [24]. RUT and p(RUT) micro/nanogel were prepared at 500 μg/mL concentration in DI water and diluted to 250, 125, 62.5, and 31.125 µg/mL concentrations.…”