Double-wavelength overlapping resonance Rayleigh scattering technique for the simultaneous quantitative analysis of three β-adrenergic blockade

Antibody-labeled gold nanoparticle based resonance Rayleigh scattering detection of S100B

Traumatic brain injury (TBI) is a sudden brain injury due to an external force that causes a large number of deaths and permanent disabilities every year. S100B has been recognized as a potential objective quantitative biomarker for screening the prognosis of TBI and severe head injury. In this article, an anti-S100B monoclonal antibody was immobilized on cysteamine (Cy) functionalized gold nanoparticles (AuNPs) by EDC-NHS chemistry, which enabled S100B resonance Rayleigh scattering (RRS) detection based on antibody-labeled gold nanoparticles. The prepared conjugates were characterized by ultraviolet-visible spectroscopy (UV-vis), transmission electron microscopy (TEM), Fourier transform infrared spectroscopy (FTIR), dynamic light scattering (DLS) and sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE). Based on the specific binding of the antibody and antigen, the RRS intensities at 381 nm and 541 nm wavelengths were significantly enhanced, and thus a dual wavelength overlapping resonance Rayleigh scattering (DWO-RRS) method was established. The scattering intensity of the two overlapping peaks was proportional to the concentration of S100B in the range of 0.05-4.5 ng mL-1 with a detection limit of 0.002 ng mL-1. The proposed DWO-RRS method is time-saving, simple, sensitive, and can be used to determine the concentration of S100B in human serum with satisfactory results, which has a promising application in the early diagnosis of TBI.

Application of Gelatin Decorated with Allura Red as Resonance Rayleigh Scattering Sensor to Detect Chito-Oligosaccharides

A convenient and sensitive triple-wavelength overlapping resonance Rayleigh scattering (TWO-RRS) method for the detection of chito-oligosaccharides (COS) was proposed based on enhancing the rigid surface of porous reticular spatial structure of gelatin and COS by introducing allura red AC (AR). The interaction and resultant porous reticular spatial structure were characterized with transmission electron microscopy (TEM), RRS, and UV-Vis spectroscopy. The results indicated that gelatin and COS formed porous reticular spatial structure with an average diameter of 1.5-2.0 μm, and the RRS value of COS-AR-gelatin ternary system with gelatin participation was significantly higher than that of COS-AR binary system. Under the optimal conditions, the enhanced TWO-RRS intensity of the system was linearly proportional to COS concentration in the range of 0.30-2.50 μg/mL, and the regression equation was ΔI = 4933.2c-446.21 with R2 = 0.9980. The limit of detection was 0.0478 μg/mL. So, a new method for the detection of COS was established and verified in the health products with satisfactory results.

Spectrofluorimetric Determination of Atenolol and Carvedilol in Pharmaceutical Preparations after Optimization of Parameters using Response Surface Methodology

Background: The present work is aimed to study the effect of different parameters on the fluorescence intensity of atenolol (ATE) and carvedilol (CAR) and optimization by response surface methodology (RSM) to provide a simple analytical method for their quantification in pharmaceutical formulations. Methods: Various parameters affecting the fluorescence intensity, i.e., sodium dodecyl sulfate (SDS) concentration, pH, volume fraction of solvents were optimized using RSM. Then, the optimized parameters were applied to the validation of a method for fluorimetric determination of β-blockers in their pharmaceutical preparations. Results: It is obtained that under the optimum conditions for determination of ATE, the method provided a linear range between 130 to 750 ng/mL with a coefficient of correlation (r) of 0.9996. Also, the limit of detection and limit of quantification (LOD and LOQ) were 40 ng/mL and 130 ng/mL, respectively. Moreover, it is observed that, the linearity of method for determination of CAR was between 0.37 to 4.0 ng/mL and LOD and LOQ of method were 0.11 ng/mL and 0.37 ng/mL, respectively. Conclusion: An accurate, sensitive and reliable spectrofluorimetric method was developed anf successfully used to determine the (ATE) and carvedilol (CAR) in their pharmaceutical preparations.

The triple-wavelength overlapping resonance Rayleigh scattering method and the fluorescence quenching method for the determination of chitooligosaccharides using trisodium-8-hydroxypyrene-1,3,6-trisulfonate as a probe

In this assay, the triple-wavelength overlapping resonance Rayleigh scattering (TWO-RRS) method and the fluorescence quenching method for the quantitative detection of chitooligosaccharides (COS) were developed. In the weakly Britton-Robinson buffer solution, COS interacted with Trisodium-8-hydroxypyrene-1,3,6-trisulfonate (HPTS) to form an ion-association complex of HPTS-COS, which increased the RRS intensities at 321 nm, 430 nm and 511 nm and decreased the fluorescence intensities of the system at 512 nm. And the changes in the intensities of both methods were related to the changes in the concentration of COS. Moreover, for the TWO-RRS method, OP-10 made the RRS intensities increased stronger, finally, the three peaks' total was linear to the concentration of COS in the range of 1.00-8.00 μg/mL and the limit of detection (LOD) was 0.247 μg/mL, and for the fluorescence quenching method, the linear range was 0.50-3.50 μg/mL with the LOD of 0.108 μg/mL. Based on these, two new and fast spectral methods with high sensitivity and simplicity for the determination of trace COS had been established. The generation mechanism of the TWO-RRS and the fluorescence quenching was studied. At the same time, the two methods were applied to the determination of COS in health products with satisfactory results.

Ultrasonication-assisted synthesis of sphere-like strontium cerate nanoparticles (SrCeO3 NPs) for the selective electrochemical detection of calcium channel antagonists nifedipine

In this work, strontium cerate nanoparticles (SrCeO₃ NPs, SC NPs) were developed through facile synthetic techniques (Ultrasound-Assisted (UA) and Stirring-Assisted (SA) synthesis) and utilized as an electrocatalyst for the selective and sensitive electrochemical detection of calcium channel blocker nifedipine (NDF). The as-prepared UASC NPs and SASC NPs were characterized using XRD, Raman, TEM, EDS, mapping, XPS and BET analysis which exposed the formation of SC NPs in the form of spherical in shape and well crystalline in nature. BET studies reveal that UASC NPs have maximum surface area than that of SASC NPs. Further, the use of the as-developed UASC NPs and SASC NPs as an electrocatalyst for the detection of NDF. Interestingly, the UASC NPs modified screen printed carbon electrode (UASC NPs/SPCE) exhibited an excellent electrocatalytic activity in terms of lower reduction potential and enhanced reduction peak current when compared to SASC NPs and unmodified SPCE. Moreover, as-prepared UASC NPs/SPCE displayed wide linear response range (LR, 0.02-174 µM), lower detection limit (LOD, 5 nM) and good sensitivity (1.31 µA µM^-1 cm^-2) than that of SASC NPs (LR = 0.02-157 µM, LOD = 6.4 nM, sensitivity - 1.27 µA µM^-1cm^-2). Furthermore, UASC NPs/SPCE showed an excellent selectivity even in the existence of potentially co-interfering compounds such as similar functional group containing drugs, pollutants, biological substances and some common cations/anions. The developed sensor was successfully employed for the determination of NDF in real lake water, commercial NDF tablet and urine samples with acceptable recovery.

A novel spectral method for determination of trace malathion using EryB as light scattering probe by resonance Rayleigh scattering technique

A convenient and sensitive spectrophotometric methods was proposed for determination of Malathion (Mala) using Erythrosin B (EryB) as a probe through the Resonance Rayleigh scattering (RRS) technique. The interaction between EryB, Pd²⁺and malathion in the system was investigated by fluorescence, RRS and UV-Vis spectroscopy. Under the optimum conditions, the RRS intensity of EryB, Pd²⁺ and malathion was weak when exist in alone or any two kinds, however, the RRS intensity of the EryB-Pd²⁺-Mala system had an obvious enhancement due to Pd²⁺ could interact with the hydrolysis products of Mala and EryB each other form a new complexes. At the same time, the fluorescence intensity of EryB was decreased significantly in the presence of Pd²⁺, and the fluorescence intensity of EryB-Pd²⁺ system further decreased when Mala added, interestingly. So it was further proved that there was a forming complex in EryB-Pd²⁺-Mala system. Under the optimal conditions, the RRS enhanced intensity of the system was linearly proportional to the Mala's concentration in the range of 0.012-0.8 μg/mL, and the LOD was 1.7 ng/mL, with the correlation coefficient was R² = 0.9960. So, a new method for determination of Mala was established and this method has been demonstrated in real sample with satisfactory results.

The fluorescence and resonance Rayleigh scattering spectra study on the interactions of palladium (II)-Nootropic chelate with Congo red and their analytical applications

A highly sensitive detection approach of resonance Rayleigh scattering spectra (RRS) is firstly applied to analyzing nootropic drugs including piracetam (PIR) and oxiracetam (OXI). In HCl-NaAc buffer solution (pH=3.0), the OXI chelated with palladium (II) to form the chelate cation [Pd₂·OXI]²⁺, and then reacted with Congo red (CGR) by virtue of electrostatic attraction and hydrophobic force to form binary complex [Pd₂·OXI]. CGR₂, which could result in the great enhancement of RRS. The resonance Rayleigh scattering signal was recorded at λ_ex=λ_em=375nm. This mixture complex not only has higher RRS, but also makes contribution to significant increase of fluorescence, and the same phenomena also were discovered in PIR. The enhanced RRS intensity is in proportion to the PIR and OXI concentration in the range of 0.03-3.0μgmL^-1, and the detection limit (DL) of RRS method for PIR and OXI is 2.3ngmL^-1 and 9.7ngmL^-1. In addition, the DL of fluorescence method for PIR and OXI is 8.4μgmL^-1 and 19.5μgmL^-1. Obviously, the RRS is the highly sensitive method, and the recoveries of the two kinds of nootropic drugs were range from 100.4% to 101.8.0% with RSD (n=5) from 1.1% to 3.1% by RRS method. This paper not only investigated the optimum conditions for detecting nootropics with using RRS method, but also focused on the reasons for enhancing RRS intensity and the reaction mechanism, which in order to firm and contract the resultant. Finally, The RRS method has been applied to detect nootropic drugs in human urine samples with satisfactory results.