CdS nanoparticles composited with carbon nanotubes not only enhances their electrochemiluminescent intensity but also decreases their ECL starting potential; such a property would promote the application of quantum dots in fabricating sensors for chemical and biochemical analysis.
Rapid and simple LFIA strips based on Au NPs provide a preliminary test result for physicians to make the correct diagnosis of SARS-CoV-2 infections along with alternative testing methods.
This work reports on a facile, economical, and green preparative strategy toward water-soluble, fluorescent oxygen-doped, nitrogen-rich, photoluminescent polymer carbon nanoribbons (ONPCRs) with a quantum yield of approximately 25.61% by the hydrothermal process using uric acid as a carbon-nitrogen source for the first time. The as-prepared fluorescent ONPCRs showed paddy leaf-like structure with 80-160 nm length and highly efficient fluorescent quenching ability in the presence of mercury(II) (Hg(2+)) or silver (Ag(+)) ions due to the formed nonfluorescent metal complexes via robust Hg(2+)-O or Ag(+)-N interaction with the O and N of fluorescent ONPCRs, which allowed the analysis of Hg(2+) and Ag(+) ions in a very simple method. By employing this sensor, excellent linear relationships existed between the quenching degree of the ONPCRs and the concentrations of Hg(2+) and Ag(+) ions in the range of 2.0 nM to 60 μM and 5.0 nM to 80 μM, respectively. By using ethylenediaminetetraacetate and ammonia as the masking agent of Hg(2+) and Ag(+) ions, respectively, Hg(2+) or Ag(+) ions were exclusively detected in coexistence with Ag(+) or Hg(2+) ions with high sensitivity, and the detection limits as low as 0.68 and 1.73 nM (3σ) were achieved, respectively, which also provided a reusable detection method for Hg(2+) and Ag(+) ions. Therefore, the easily synthesized fluorescent ONPCRs may have great potential applications in the detection of Hg(2+) and Ag(+) ions for biological assay and environmental protection.
The major goal of this work was to develop a new solid-state electrochemiluminescence (ECL) detector suitable for capillary electrophoresis (CE). The detector was fabricated by coating a sol-gel derived zirconia (ZrO(2))-Nafion composite film on a graphite electrode, then the zirconia-Nafion modified electrode was immersed in tris(2,2'-bipyridyl)ruthenium(II) (Ru(bpy)(3) (2+)) solution to immobilize this active chemiluminescence reagent. The voltammetric and ECL behaviors of the detector were investigated and optimized in tripropylamine solution. The ratio of 53% for zirconia in the zirconia-Nafion composite provided the highest luminescence intensity of immobilized Ru(bpy)(3) (2+). The ECL can maintain its stability very well in the phosphate solution in the period of 5-90 h when the solid-state ECL detector was immersed in the solution all the time. The optimum distance of capillary outlet to the solid-state ECL detector has been found to be ca. 50-80 microm for a 75 microm capillary. The effects of ionic strength and pH of ECL solution on peak height were investigated. The CE with solid-state ECL detector system was successfully used to detect tripropylamine, lidocaine, and proline. The detection limits (S/N = 3) were 5 x 10(-9) mol.L(-1) for tripropylamine, 1 x 10(-8) mol.L(-1) for lidocaine and 5 x 10(-6) mol.L(-1) for proline, and the linear ranges were from 1.0 x 10(-8) to 1.0 x 10(-5) mol.L(-1) for tripropylamine, 5.0 x 10(-7) mol.L(-1) to 1.0 x 10(-5) mol.L(-1) for lidocaine and 1.0 x 10(-5) to 1.0 x 10(-3) mol.L(-1) for proline, respectively.
Sensitive detection of severe fever with thrombocytopenia
syndrome
virus (SFTSV) by a point-of-care assay is of great significance for
promoting clinical diagnosis. In this work, ultrasensitive detection
of SFTSV was achieved by using fluorescent carbon dots/SiO2 nanospheres (CSNs) as reporters for a lateral flow assay. The prepared
CSNs were resistant to extreme environments and had strong stability.
The uniform CSNs with the size of about 200 nm were obtained by differential
centrifugation. Their absolute quantum yields in the aqueous and solid
phases are 56.3 and 36.6%, respectively. The excellent fluorescent
properties of CSNs make the test strips more sensitive and have a
longer assay lifetime. Thus, the visual detection limit of the lateral
flow test strip based on immunofluorescent CSN (iCSN) was as low as
10 pg/mL SFTSV nucleoprotein. The sensitivity of this assay is 2 orders
of magnitude higher than that of the colloidal gold-based lateral
flow test strip. Besides, the assay owns good reproducibility and
high specificity. Then, iCSN-based lateral flow test strips were evaluated
in real samples of human serum of patients with satisfactory results.
Furthermore, this assay has a general prospect for other fluorescent
immunochromatography applications.
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