ABSTRACT
Two inexpensive and simple methods for synthesis of carbon nanodots were applied and compared to each other, namely a hydrothermal and microwave-assisted method. The synthesized carbon nanodots were characterized using transmission electron microscopy (TEM), ultraviolet-visible (UV-Vis), photoluminescence (PL), Fourier transform-infrared spectroscopy (FTIR), and X-ray diffraction (XRD). The synthesized microwave carbon nanodots had smaller particle size and were thus chosen for better electrochemical performance. Therefore, they were used for our modification process. The proposed electrodes performance characteristics were evaluated according to the IUPAC guidelines, showing linear response in the concentration range 10−6–10−2, 10−7–10−2, and 10−8–10−2 M of tobramycin with a Nernstian slope of 52.60, 58.34, and 57.32 mV/decade for the bare, silver nanoparticle and carbon nanodots modified carbon paste electrodes, respectively. This developed potentiometric method was used for quantification of tobramycin in its co-formulated dosage form and spiked human plasma with good recovery percentages and without interference of the co-formulated drug loteprednol etabonate and excipients.
ABSTRACT
The COVID-19 pandemic has increased the usage of personal protective equipment (PPE) all round the world and, in turn, it has also increased the waste caused by disposable PPE. This has exerted a severe environmental impact, so in our work, we propose the utilization of a sustainable electrospun nanofiber based on poly lactic acid (PLA), as it is biobased and conditionally degradable. We optimized the weight percentage of the PLA-precursor solution and found that 19% PLA produces fine nanofibers with good morphology. We also introduced carbon nanodots (CNDs) in the nanofibers and evaluated their antibacterial efficiency. We used 1, 2, 3, and 4% CNDs with 19% PLA and found increased antibacterial activity with increased concentrations of CNDs. Additionally, we also applied a spunbond-nanofiber layered assembly for the medical face masks and found that with the addition of only 0.45 mg/cm2 on the nonwoven sheet, excellent particle filtration efficiency of 96.5% and a differential pressure of 39 Pa/cm2 were achieved, meeting the basic requirements for Type I medical face masks (ASTM-F2100).
ABSTRACT
Localized surface plasmon resonance of Au nanodots array are very sensitive and resonance field disturbance due to 100 nm sized SARS-CoV-2 virus can be detected via resonance wavelength shift. We have proposed Au nanodots (100 nm diameter and 200 nm pitch) array plasmonic biosensing platform for SARS-CoV-2 virus detection. © 2022 The Author(s).
ABSTRACT
The development of DNA-sensing platforms based on new synthetized Methylene Blue functionalized carbon nanodots combined with different shape gold nanostructures (AuNs), as a new pathway to develop a selective and sensitive methodology for SARS-CoV-2 detection is presented. A mixture of gold nanoparticles and gold nanotriangles have been synthetized to modify disposable electrodes that act as an enhanced nanostructured electrochemical surface for DNA probe immobilization. On the other hand, modified carbon nanodots prepared a la carte to contain Methylene Blue (MB-CDs) are used as electrochemical indicators of the hybridization event. These MB-CDs, due to their structure, are able to interact differently with double and single-stranded DNA molecules. Based on this strategy, target sequences of the SARS-CoV-2 virus have been detected in a straightforward way and rapidly with a detection limit of 2.00 aM. Moreover, this platform allows the detection of the SARS-CoV-2 sequence in the presence of other viruses, and also a single nucleotide polymorphism (SNPs). The developed approach has been tested directly on RNA obtained from nasopharyngeal samples from COVID-19 patients, avoiding any amplification process. The results agree well with those obtained by RT-qPCR or reverse transcription quantitative polymerase chain reaction technique.
ABSTRACT
Baicalin, a flavonoid compound extracted from the rhizome of Scutellar iae Baicalensis, plays a vital role in improving liver function after injury, reducing liver disease and treating primary liver cancer, which is also the first SARS-CoV-2 3CLpro virus inhibitor according to the latest research data published in Bio-Rxiv. Therefore, constructing a simple and highly sensitive analytical method for the determination of baicalin is of great significance for the clinical and pharmacy settings. Herein, for the first time, carbon dots are explored for baicalin detection. Using biomass waste grape peels as the organic carbon source, nitrogen-doped fluorescent carbon dots (PT-NCDs) were fabricated, which were synthesized perfectly by a simple, environmentally friendly and one-step solid-phase thermal method without adding any other organic or acid/base reagents. Based on the synergistic effect of photo-induced electron transfer and dynamic quenching, a quenched fluorescence sensor for the determination of baicalin with a good linear range of 0.1-20 mu M and a satisfactory detection limit of 43.8 nM was constructed, which successfully quantified trace amount of baicalin in baicalin capsules, human serum and urine samples. The results indicate that PT-CDs are expected to become potential sensing materials for the real-time monitoring of baicalin in organisms, which is very important for our health. (C) 2021 Elsevier Ltd. All rights reserved.