Spectrophotometric determination of norfloxacin using bromophenol blue

Novel Flavonol Derivatives Containing Quinoxaline: Insights into the Antifungal Mechanism against Sclerotinia sclerotiorum

In this study, 12 pairs of tautomeric flavonol derivatives containing quinoxaline were synthesized. The results of antifungal activity showed that in the enol-keto tautomerism, the target compounds containing keto (YB series) had better inhibitory activity against Sclerotinia sclerotiorum (S.s.) than compounds containing enol (YA series). YB9 showed the strongest antifungal activity against S.s., and the median effective concentration (EC50) value was 1.0 μg/mL, which was better than azoxystrobin (Az, 35.3 μg/mL). In vivo fungal inhibition experiments showed that the protective activity of YB9 against rape leaves was 83.4% at 200 μg/mL, which was superior to that of Az (70.2%). The activity of succinate dehydrogenase and molecular docking results showed that YB9 had a stronger antifungal effect than YA9. The results of oxalic acid content determination showed that YB9 could reduce the pathogenic ability of S.s. Then, the inhibitory effect of YB9 against S.s. was further verified by scanning electron microscopy, fluorescence microscopy, cell membrane permeability, cell content leakage, and malondialdehyde content.

A cutting-edge electrochemical sensing platform for the simultaneous determination of the residues of antimicrobial drugs, rifampicin and norfloxacin, in water samples

BACKGROUND

The widespread use and abuse of antibiotics has resulted in the pollution of water sources with antibiotic residues, posing a threat to human health, the environment, and the economy. Therefore, a highly sensitive and selective method is required for their detection in water samples. Herein, advanced ultrasensitive electrochemical sensor platform was developed by integrating gold-silver alloy nanocoral clusters (Au-Ag-ANCCs) with functionalized multi-walled carbon nanotube-carbon paste electrode (f-MWCNT-CPE) and choline chloride (ChCl) nanocomposites for simultaneously determining the residues of antimicrobial drugs, rifampicin (RAMP) and norfloxacin (NFX), in water samples.

RESULTS

The developed sensor (Au-Ag-ANCCs/f-MWCNTs-CPE/ChCl) was extensively characterized using several analytical (UV-Vis, FT-IR, XRD, SEM, and EDX) and electrochemical (EIS, CV, and SWV) techniques. It exhibited outstanding performance in a wide linear range, from 14 pM to 115 μM for RAMP, and from 0.9 nM to 200 μM for NFX, with a limit of detection (LOD, 3σ/m, S/N = 3, n = 5) and a limit of quantification (LOQ, 10σ/m, S/N = 3, n = 5) values of 2.7 pM and 8.85 pM for RAMP, and 0.14 nM and 0.47 nM for NFX, respectively. The sensor also exhibited exceptional reproducibility, stability, and resistance to interference.

SIGNIFICANCE

The developed sensor was effectively utilized to determine RAMP and NFX residues in hospital wastewater, river, and tap water samples, yielding recoveries within the range of 96.8-103 % and relative standard deviations below 5 %. Generally, the proposed sensor demonstrated remarkable performance in detecting the target analytes, making it an ideal tool and the first of its kind for addressing global antibiotic residue pollutants in water sources.

Multifunctional Portable System Based on Digital Images for In-Situ Detecting of Environmental and Food Samples

The development of a portable device created by 3D printing for colorimetric and fluorometric measurements is an efficient tool for analytical applications in situ or in the laboratory presenting a wide field of applications in the environmental and food field. This device uses a light-emitting diode (LED) as radiation source and a webcam as a detector. Digital images obtained by the interaction between the radiation source and the sample were analyzed using a programming language developed in Matlab (Mathworks Inc., Natick, MA, USA), which builds the calibration curves in real-time using the RGB colour model. In addition, the entire system is connected to a notebook which serves as an LED and detector power supply without the need for any additional power source. The proposed device was used for the determination in situ of norfloxacin, allura red, and quinine in water and beverages samples, respectively. For the validation of the developed system, the results obtained were compared with a conventional spectrophotometer and spectrofluorometer respectively with a t-test at a 95% confidence level, which provides satisfactory precision and accuracy values.

Facile synthesis of surface functionalized Pd2+@P-CDP/COFs for highly sensitive detection of norfloxacin drug based on the host-guest interaction

In this work, β-cyclodextrin porous polymers (P-CDPs) functionalized novel covalent organic frameworks (P-CDPs/COFs) were synthesized by a simple and facile method. After combined with Pd²⁺ via electrostatic interaction, the Pd²⁺@P-CDPs/COFs nanocomposites were prepared and utilized as novel electrode materials to fabricate the non-enzyme electrochemical sensors for high-sensitivity detection of Norfloxacin (NF). Due to the host-guest recognition, excellent adsorption performance and catalytic performance of Pd²⁺@P-CDPs/COFs, the prepared sensor exhibited excellent electrochemical performance for detecting NF under the optimum conditions, which showed two linear ranges of 0.08-7.0 μM and 7.0-100.0 μM with a low detection limit of 0.031 μM (S/N = 3). Additionally, the obtained sensor has also been successfully applied to measure NF with satisfactory results in the real medicinal samples of NF eye-drops. Our findings paved the way for the development of COFs-based sensing platform in drug analysis and testing for human health, food security and the quality control of drugs.

Algae-induced photodegradation of antibiotics: A review

Antibiotics are a typical group of pharmaceutical and personal care products (PPCPs) with emerging pollutant effects. The presence of residual antibiotics in the environment is a prominent issue owing to their potential hazards, toxic effects, and persistence. Several treatments have been carried out in aquatic environments in order to eliminate antibiotic residues. Among these, photodegradation is regarded as an environmentally-friendly and efficient option. Indirect photodegradation is the main pathway for the degradation of residual antibiotics in natural water, as opposed to direct photodegradation. Algae, working as photosensitizers, play an important role in the indirect photolysis of residual antibiotics in natural water bodies. They promote this reaction by secreting extracellular organic matters (EOMs) and inducing the generation of active species. In order to provide a thorough understanding of the effects of algae on residual antibiotic degradation in the environment, this paper comprehensively reviews the latest research regarding algae-induced antibiotic photodegradation. The summary of the different pathways and photosensitive mechanisms involved in this process show that EOMs are indispensable to antibiotic photodegradation. The influencing factors of algae-induced photodegradation are also discussed here: these include algae species, antibiotic types, and environmental variables such as light source, ferric ion presence, temperature, and ultrasound treatment. Based on the review of existing literature, this paper also considers several pathways for the future study of algae-induced antibiotic photodegradation.