Rapid determination of marbofloxacin by surface-enhanced Raman spectroscopy of silver nanoparticles modified by β-cyclodextrin

Boric acid-functionalized silver nanoparticles as SERS substrate for sensitive and rapid detection of fructose in artificial urine

The accurate detection of fructose in human urine can help prevent and screen for diseases such as fructokinase deficiency and hereditary fructose intolerance. Surface-enhanced Raman spectroscopy (SERS) is an analytical technique with selectivity and high sensitivity, which has been widely applied to the detection of targets with complex backgrounds. In this work, 4-mercaptophenylboronic acid (4-MPBA) was modified on the surface of silver nanoparticles (AgNPs) under mild conditions to obtain a boronic acid-functionalized SERS substrate for the detection of fructose in artificial urine. The detection mechanism was based on the deboronization reaction of 4-MPBA on the surface of AgNPs, which was induced by fructose, and the Raman signal of the generated thiophenol (TP) molecules was significantly enhanced by the silver nanoparticles, with a linear increase in SERS peak intensity at 1570 cm^-1. We achieved the detection limits of 0.084 µmol/L in water and 0.535 µmol/L in urine by this method. The relative standard deviation (RSD) in the recovery experiments of urine ranged from 1.01 % to 2.22 %, and the whole detection time was less than 10 min, which indicated that this method is highly reliable for fructose detection and has a good prospect in bioassay and clinical medicine.

Utility of Silver-nanoparticles for Nano-fluorimetric Determination of Vancomycin Hydrochloride in Pharmaceutical Formulation and Biological Fluids: Greenness Assessment

Vancomycin hydrochloride (VANH) is a glycopeptide antibiotic commonly employed in the prophylaxis and therapy of various gram-positive bacterial life-threatening infections. Due to the narrow therapeutic window of VANH, its serum levels should be well-monitored to avoid its toxicity and to optimize its therapy. Herein, an innovative silver-nanoparticles enhanced fluorescence technique was designed for VANH rapid analysis in its pharmaceutical formulation and biological fluids. This technique is based on reinforcement of VANH fluorescence intensity with silver-nanoparticles that were synthesized by a redox reaction between VANH and silver nitrate in NaOH alkaline medium using polyvinylpyrrolidone as a stabilizer. The produced silver-nanoparticles were characterized by using UV-visible spectroscopy where they have an intense absorption maximum at 415 nm and transmission electron microscope (TEM) micrograph where they are spherical in shape with smooth surface morphology and size of 10.74 ± 2.44 nm. The fluorescence intensity was measured at 394 nm after excitation at 259 nm. Under optimum conditions, a good linear relationship was accomplished between the VANH concentration and the fluorescence intensity in a range of (1-36) ng/mL with a limit of detection of 0.29 ng/mL. Greenness assessment was performed using two assessment tools namely; eco-scale scoring and green analytical procedure index revealing excellent greenness of the proposed technique. The proposed technique was validated according to the International Conference on Harmonisation (ICH) recommendations and statistically compared with the reported HPLC method revealing no significant difference concerning accuracy and precision at p = 0.05. The proposed technique depended primarily on water as a cheap and eco-friendly solvent.

An Overview of Analytical Methods for the Quantification of Marbofloxacin in Pharmaceutical, Biological and Food Matrices

BACKGROUND

Marbofloxacin (MAR), a second-generation fluoroquinolone, is used in veterinary medicine in the form of tablets. It has a broad spectrum of action, low toxicity, and limited development of bacterial resistance. The analytical methods available in the literature become more important since MAR in tablets does not have a monograph in official compendiums.

OBJECTIVE

Thus, the purpose of this review is to display them according to the analyzed matrix and place them according to the conditions used in the scope of green analytical chemistry, in addition to discussing possible gaps and opportunities for the development of new methods.

RESULTS

MAR, being an antimicrobial, presents both physical-chemical (93%) and microbiological (7%) methods in the literature. Among the methods found, 53% are for analysis of food matrices using preferably HPLC and TLC-MS. 27% are for analysis of biological matrices and 20% are for analysis of pharmaceutical matrices, and in both HPLC is preferably used.

CONCLUSIONS

Therefore, there is still a gap in the literature in relation to other options of analytical methods for the analysis of MAR, which are faster, such as microbiological turbidimetry, sustainable, such as miniaturized methods, and ecologically correct, such as those that do not usetoxic organic solvents.

HIGHLIGHTS

A review of the status of analytical methods available in the literature for assessing the quality of MAR and MAR-based products were exhibited and discussed, as well as new opportunities for analysis according to green analytical chemistry.

Cyclodextrin-assisted surface-enhanced Raman spectroscopy: a critical review

Numerous approaches have been proposed to overcome the intrinsically low selectivity of surface-enhanced Raman spectroscopy (SERS), and the modification of SERS substrates with diverse recognition molecules is one of such approaches. In contrast to the use of antibodies, aptamers, and molecularly imprinted polymers, application of cyclodextrins (CDs) is still developing with less than 100 papers since 1993. Therefore, the main goal of this review is the critical analysis of all available papers on the use of CDs in SERS analysis, including physicochemical studies of CD complexation and the effect of CD presence on the Raman enhancement. The results of the review reveal that there is controversial information about CD efficiency and further experimental investigations have to be done in order to estimate the real potential of CDs in SERS-based analysis.

Surface-enhanced Raman spectroscopywith gold nanorods modified by sodium citrate and liquid-liquid interface self-extraction for detection of deoxynivalenol in Fusarium head blight-infected wheat kernels coupled with a fully convolution network

Surface-enhanced Raman spectroscopy (SERS) and deep learning network were adopted to develop a detection method for deoxynivalenol (DON) residues in Fusarium head blight (FHB)-infected wheat kernels. First, the liquid-liquid interface self-extraction was conducted for the rapid separation of DON in samples. Then, the gold nanorods modified with sodium citrate (Cit-AuNRs) were prepared as substrate for a gigantic enhancement of SERS signal. Results showed that the spectral characteristic peaks for DON residues of 99.5-0.5 mg/L were discernible with the relative standard deviation of 4.2%, with the limit of detection of 0.11 mg/L. Meanwhile, the fully convolutional network for the spectra of matrix input form was developed and obtained the optimal quantitative performance, with a root-mean-square error of prediction of 4.41 mg/L and coefficient of determination of prediction of 0.9827. Thus, the proposed method provides a simple, sensitive, and intelligent detection for DON in FHB-infected wheat kernels.

Assessment on the binding characteristics of residual marbofloxacin in animal-derived food to bovine/human serum albumin by spectroscopy and molecular modelling

To assess the toxicity of residual marbofloxacin from animal-derived food, the interaction characteristics of marbofloxacin to bovine/human serum albumins (BSA/HSA) were explored using spectroscopic methods combined with molecular modelling. According to fluorescence spectra and time-resolved fluorescence spectra measurements, quenching of BSA/HSA fluorescence induced by marbofloxacin was characterized as static quenching. A 1:1 ground-state complex of marbofloxacin to BSA/HSA was formed with binding constant (K_a ) 1.66 × 10⁴ /9.74 × 10³ M^-1 at 291 K. The location of marbofloxacin binding at site I within BSA/HSA was clarified by site marker competitive experiments. Molecular modelling demonstrated that the binding region for marbofloxacin to BSA and HSA were at site I with the lowest binding free energies of -22.86 and -21.60 kJ mol^-1 , respectively. Hydrogen bonds and van der Waals forces were dominantly involved in the spontaneous binding. Nonradiation energy transferred from BSA and HSA to marbofloxacin, due to the close distance (r₀ ) between marbofloxacin and Trp residues of BSA (4.28 nm) and HSA (3.34 nm). As explained by circular dichroism (CD) spectra, an increased BSA/HSA α-helix structure was observed after binding to marbofloxacin. Ultraviolet-visible (UV-vis) and Fourier transform infrared (FT-IR) spectra suggested that conformation of the two proteins was altered by marbofloxacin.

Development of affinity between target analytes and substrates in surface enhanced Raman spectroscopy for environmental pollutant detection

Environmental pollution has long been a social concern due to the variety of pollutants and their wide distribution, persistence and being detrimental to health. It is therefore necessary to develop rapid and sensitive strategies to trace and detect these compounds. Among various detection methodologies, surface enhanced Raman spectroscopy (SERS) has become an attractive option as it enables accurate analyte identification, simple sample preparation, rapid detection and ultra-high sensitivity without any interference from water. For SERS detection, an essential yet challenging step is the effective capture of target analytes onto the surface of metal nanostructures with a high intensity of enhanced electromagnetic field. This review has systematically summarized recent advances in developing affinity between targets and the surface of SERS substrates via direct adsorption, hydrophobic functional groups, boronate affinity, metal organic frameworks (MOFs), DNA aptamers and molecularly imprinted polymers (MIPs). At the end of this review, technical limitations and outlook have been provided, with suggestions on optimizing SERS techniques for real-world applications in environmental pollutant detection.