查看更多>>摘要：The binding of glucosamine to gold in water solutions of glucosamine hydrochloride mixed with clean colloidal gold nanoparticles obtained by laser ablation in liquid was studied using surface-enhanced Raman scattering (SERS), dynamic light scattering (DLS) and UV-VIS spectroscopy. The purpose of this study was to establish whether the binding of charged aminogroup to gold nanoparticles (AuNPs) is taking place, and if it does, how can it be identified by means of SERS. The average size of dried gold nanoparticles was (20 +/- 4) nm determined by averaging the sizes observed in transmission electron microscopy micrographs, which is smaller than the average size of gold nanoparticles in water solution as determined by DLS: (52 +/- 2) nm. Upon adding the glucosamine solutions to gold colloid, average hydrodynamic diameter of ions was slightly larger for 0.1 mM glucosamine solution (55 +/- 2 nm), while it increased to (105 +/- 22) nm in the case of 1 mM solution, and was (398 +/- 54) nm when 10 mM glucosamine solution was added. Most prominent Raman bands observed both for 0.1 mM and 1 mM glucosamine solutions were located at 1165 cm-1, 1532 and 1586 cm-1 and assigned to C-N coupled with C-C stretching, and C NH3+ deformation angles bending. In SERS spectrum of 1 mM GlcN+ solution, two strong bands at 999 and 1075 cm-1 were found and attributed to C-Oring stretching coupled with C-NH3+ bending (999 cm-1) and to dominantly C-O stretching vibration. The differences in SERS spectra are attributed to different number of glucosamine molecules that attach to gold nanoparticles and their orientation with respect to the metal particle surface, partly due to presence of beta anomers protonated at anomeric oxygen position. The assignment of glucosamine bands was further corroborated by comparison with vibrational spectra of alpha and beta glucose and of polycrystalline powder of glucosamine hydrochloride. For all three sub-stances comprehensive calculation of vibrational density of states was conducted using density func-tional theory. Benchmark bands for polycrystalline glucose anomers distinction are 846 and 915 cm-1 for alpha glucose, and 902 cm-1 for beta glucose. However, the bands observed in SERS spectra of 0.1 mM glucosamine solution at 831, 899, and 946 cm-1 or in 1 mM solution at 934 cm-1 cannot be easily identified as belonging either to alpha or beta glucosamine anomer, due to complexity of atomic motions involved. The identification of vibrational bands associated with -CNH3+ group will aid SERS studies on amino acids, especially in cases when several atomic groups could possibly bind to AuNPs. (c) 2021 Elsevier B.V. All rights reserved.
查看更多>>摘要：A simple and sensitive spectrofluorimetric method has been developed for the estimation of Ivabradine HCl in bulk and the tablet dosage form. Ivabradine HCl in methanol produces fluorescence at 325 nm (A,em) with excitation at 287 nm (A,ex). The linearity range was found to be 100-500 ng/ml with a corre-lation coefficient of 0.999. The limit of detection (LOD) and limit of quantitation (LOQ) for the developed method were found to be 8.38 and 25.39 ng/ml, respectively. The developed method was found to be specific, sensitive, accurate, and precise. It was successfully used for the estimation of Ivabradine HCl in its tablet dosage form. The content of Ivabradine HCl in marketed formulations was found to be 101.25 +/- 1.16 % of label claims. (c) 2021 Elsevier B.V. All rights reserved.
查看更多>>摘要：Biological microenvironment plays a momentous role in the regulation of various vital activities, and its abnormal changes are often closely related to some diseases. Viscosity, as an indispensable part of microenvironment parameters, has always been one of the research hotspots of investigators. Herein, we constructed a new red-emitting fluorescent probe (HVM) to identify the abnormal situation of mitochondria through viscosity changes in the biological microenvironment. Interestingly, HVM has excellent optical properties such as large stokes shift (160 nm), viscosity sensitivity (195-fold), high photostability, and biochemical properties with low cytotoxicity and excellent biocompatibility. For these reasons, the novel probe could successfully be used to identify the normal and inflammatory models via viscosity changes in biological experiments. Therefore, we provided a convenient synthetic route to obtain viscosity sensor HVM with excellent application properties. CO 2021 Published by Elsevier B.V.
查看更多>>摘要：In this paper, two tetrahydo[5]helicene-based dyes (THH1 and THH2) were studied on their twist intramolecular charge transfer. And the water-soluble blue carbon dots (N-CDs) were synthesized. Considering that their different optical propeties, the ratiometric fluorescence probes N-CDs/THH1 and N-CDs/THH2 were constructed by mixing N-CDs and dyes simply. It was found that N-CDs/THH1 and N-CDs/THH2 could quickly and sensitively detect water content in ethanol, with linear range of 0.500 25.0 vol% and 0.50030.0 vol%, respectively. Whats more, through the actual sample test, it showed that the detection had good accuracy and precision. At the same time, it was found that two ratiometric probes could also be applied to the thermometry with good reversibility based on optical temperature sensors. (c) 2021 Elsevier B.V. All rights reserved.
查看更多>>摘要：The optical sensor with ratiometric and turn-off dual modes is constructed to detect H2O2 and glucose based on blue fluorescent carbon dots (CDs) and MnO2 nanosheets with great ability of fluorescence quenching and scattering. Employing CDs@MnO2 nanosheets nanocomposite as the probe, H2O2 is detected by simultaneously collecting first-order scattering (FOS, 353.5 nm), fluorescence (440 nm), and second-order scattering (SOS, 710 nm) under the excitation of 350 nm. H2O2 with strong oxidation property can etch the lamellar structure of MnO2 nanosheets into nano-fragments, which made the fluorescence of CDs in the system recover and the scattering intensity (FOS and SOS) of the system decrease significantly. Therefore, the optical sensor combined FOS and fluorescence signals in ratiometric mode, and SOS signal in turn-off mode to realize sensitive determination of H2O2. The linear ranges of ratiometric mode and turn-off mode for H2O2 detection were 0.2-40 and 0.2-15 mu M, respectively. And the limits of detection (LODs) of two modes were 73 and 104 nM, respectively. Furthermore, the sensor was also successfully applied to the detection of glucose which can react to produce H2O2. Satisfactorily, the LODs of this sensor for glucose detection were 95 and 113 nM for ratiometric mode and turn-off mode, respectively. This work not only provides a new method for the accurate detection of H2O2 and glucose, but also extends a new idea for the study of the combination of scattering and fluorescence. (C) 2021 Elsevier B.V. All rights reserved.
查看更多>>摘要：Spectral unmixing algorithm is one of the key technologies for spectral flow cytometer in biology, chemistry and medicine. The proposed algorithm can separate the overlapping spectra automatically without the premeasured single stained or un-stained samples as the basic pure spectra. Genetic algorithm is adopted to search the optimal positions and peak sharps of the basic spectra derived from the unknown components, and then the concentration of each component can be estimated simultaneously by least squares method. Compared with conventional methods, the proposed algorithm has a wider application scope, such as the multi-stained samples with unknown components or the samples with auto fluorescence. In the simulation, the convergence rate, accuracy and stability of the proposed algorithm are evaluated under the conditions of completely and partly unknown components. In the experiment, the flow spectra of cyanobacteria are processed, and the results demonstrate the feasibility and effectiveness of the proposed algorithm. (c) 2021 Elsevier B.V. All rights reserved.
Abd El-Aziz, HebaFathy, M. E.El-Enany, N.Aly, F. A....
10页
查看更多>>摘要：For the estimation of some co-administered antimicrobials, two highly accurate and precise spectrofluorimetric methods were developed. Fluconazole (FLZ) is co-administered with either ciprofloxacin (CPR) or ofloxacin (OFX) for the treatment of certain microbial infections. On the other hand, another antimicrobial drug, vancomycin (VNC) is co-administered with ciprofloxacin (CPR) for peritonitis treatment. In method I, conventional spectrofluorimetry has been introduced for the concurrent quantitative estimation of FLZ in presence of OFX or CPR. While in method II, a first derivative synchronous spectrofluorimetric technique was adapted for quantitation of VNC and CPR co-administered combination. Both of them were utilized for estimation of the considered drugs in raw materials, laboratory prepared mixtures, dosage forms, and biological fluids. Method I was relied on simultaneous measuring of the native fluorescence of FLZ and OFX or CPR without any overlapping between the emission spectra of each binary mixture (FLZ / OFX) and (FLZ / CPR). Fluorescence intensities were measured at 283.0, 483.0 and 436.0 nm after excitation at 262.0, 292.0 and 275.0 nm for FLZ, OFX and CPR, respectively. Method II was utilized the synchronous fluorescence intensity of VNC and CPR in methanol at Delta lambda = 40 nm. The first derivative synchronous spectra were calibrated at 297.0 nm for VNC and at 379.5 nm for CPR. Different variables influencing conventional and synchronous fluorescence intensities of the four antimicrobials under investigation were precisely optimized. Both methods were successfully investigated for the determination of the studied drugs in plasma. The linear data analysis for the calibration curves reveals a good relationship in the ranges of 1.0-10.0, 0.25-2.5 and 0.06-0.6 mu g/mL for FLZ, OFX and CPR for method I with limits of detection 0.144, 0.038 and 0.007 mu g/mL and limits of quantitation of 0.437, 0.114 and 0.021 mu g/mL for FLZ, OFX and CPR, respectively. Linearity range for method II was 0.5-10.0 mu g/mL for VNC and CPR with detection limits of 0.127 and 0.110 lg/mL and quantitation limits of 0.380 and 0.334 lg/mL for VNC and CPR, respectively. International Council on Harmonization ICH Q2 (R1) Guidelines were followed in the developed methods validation. The achieved outcomes were statistically compared with those found by the reported ones, and no significant difference was observed. (C) 2021 Published by Elsevier B.V.
查看更多>>摘要：Enhanced 'Antenna effect' of a suitably designed ternary complex of Eu(III), Tetracycline hydrochloride (TC) and globular proteins viz bovine serum albumin (BSA), human serum albumin (HSA) and beta-lactoglobulin A (BLGA) in aqueous medium is employed to characterize the different partially unfolded states along with investigation of the micro- heterogeneous environment of the proteins during their stepwise unfolding. The zone-wise perturbation for the proteins upon denaturation by Urea and Guanidine hydrochloride (Gdn. HCl) is followed by the emission of Eu(III) through 'Antenna Effect' and that of the tryptophan (Trp) residues of the proteins as a function of denaturants both by steady state and time resolved emission study. With Gdn. HCl as denaturant, both BSA and BLGA show quenching of Eu(III) emission compared to pure protein while HSA exhibits an enhancement of antenna effect during unfolding as compared to that in its absence. In the presence of Urea, HSA and BSA show enhancement of antenna effect accompanied by Stark splitting of the D-5(0) -> F-7(2) transition of Eu(III) although BLGA follows the similar pattern of quenching of Eu(III) emission as observed with Gdn. HCl without any Stark splitting. The proteins exhibit a two state transition with Delta G(D) values of similar to 2-3 kcal mol(-1). Thus the use of Eu(III) emission as an efficient probe is advocating here to rationalize the microenvironment of the proteins during their stepwise unfolding. (C) 2021 Published by Elsevier B.V.
查看更多>>摘要：As a main extracellular metabolite of dopamine, 3-methoxytyramine (3-MT) is considered a potential biomarker of pheochromocytomas and paragangliomas. Therefore, the determination of 3-MT is of great significance in the early diagnosis of disease. However, it remains challenging for detecting 3-MT in consideration of sensitivity and accuracy. Here, a luminescent Eu3+ functionalized metal-organic frameworks (Eu3+@AI-MOF) with ultra-high chemical stability was constructed based on postsynthetic modification. Such a rational design greatly enhances the fluorescence signal of Eu3+@AI-MOF and it is endowed with excellent properties as a luminescent sensor to detect 3-MT in urine system. Intriguingly, the strong red emitting derived from antenna effect was significantly interdicted upon addition of 3-MT through the interaction between 3-MT and the ligand. The proposed sensing system exhibited many appealing analytical performances, such as excellent selectivity, high sensitivity and quick response. Remarkably, the developed paper-based sensor not only provides a portable and reliable strategy for direct detection of 3-MT but also expands the application of visual analysis tools. This work represents the first effort in designing a luminescent sensor to determine the metabolite biomarker 3-MT level and provides a new method for biomedical analysis. (C) 2021 Elsevier B.V. All rights reserved.
查看更多>>摘要：In this study, a facile nanoparticle catalytic sensor for resonance Rayleigh scattering quantification of mercury (II) ion was developed. The developed approach is relied on the selective inhibition of the peroxidase-like activity of polyvinylpyrrolidone-stabilized silver nanoparticles (PVP-Ag-NPs) by mercury (II) ions. The synthesized PVP-Ag-NPs oxidize the aqueous solution of O-Phenylenediamine (colorless) to 2,3-phenazinediamine (bright yellow) and their resonance Rayleigh scattering (RRS) activity was com-pletely suppressed. When mercury (II) was introduced, the RRS activity of PVP-Ag-NPs was turned on combined with a reduction of the intensity of the yellow color. The enhancement in the RRS intensity was related to the concentration of mercury (II) in the linear range of 10-2000 nM. The smaller size (4.5 nm), the large surface area and the uniform size (PDI = 0.379) of the synthesized PVP-Ag-NPs offered a higher chance for interaction between mercury (II) and PVP-Ag-NPs with the advantages of high sen-sitivity (LOD = 4 nM) and excellent selectivity for mercury (II) detection over several metals and anions. (c) 2021 Elsevier B.V. All rights reserved.
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