On-Line two dimensional liquid chromatography based on skeleton type molecularly imprinted column for selective determination of sulfonylurea additive in Chinese patent medicines or functional foods

Dummy-template Pickering emulsion imprinted microspheres online pretreatment and analysis for the estrogens in cosmetics

Estrogens are a class of steroid hormone with strong physiological activity. Due to the pronounced beauty effect, such drugs are highly susceptible to illegal addition and cause other adverse effects. To avoid template leakage and the negative impacts on the environment caused by the estrogens, diosgenin was selected as the dummy template due to its similar skeleton structure. The Pickering emulsion polymerization was used to obtain the dummy-template molecularly imprinted polymers (dt-MIPs). Scanning electron microscopy, optical microscopy, specific surface area testing, Fourier transform infrared spectroscopy and adsorption experiments were used to characterize the apparent morphology and the recognition performance of the microspheres. Then, the prepared microspheres and commercial fillers were used to construct an on-line solid phase extraction (on-line SPE) analytical system coupled with HPLC via a two-position switching valve. On-line solid phase extraction-HPLC analytical methods were established and verified, for the simultaneous determination of four estrogens in cosmetic samples. The accuracy and precision RSDs for the established methods using the imprinted sorbents were 92.00-104.02% and less than 9.12%, respectively. All four estrogens exhibited good linearity in the range of 0.05 to 5 µg/mL with a coefficient of determination R² greater than 0.9810. The method comparison results suggest that the established analytical method is simple in pre-treatment, easy to automate, and has excellent sensitivity to meet the analytical requirements of complex samples.

Complementary Strategy Enhancing Broad-Specificity for Multiplexed Immunoassay of Adulterant Sulfonylureas in Functional Food

Sulfonylureas, a family of anti-diabetic drugs widely used in the clinical treatment of type 2 diabetes, have recently emerged as an illegal adulterant in functional foods, to enhance the claimed anti-diabetic activity. To establish a screening assay method against their adulteration, with the aid of molecular simulation of hapten, two antibodies were raised and complementarily used to enhance the broad-specificity of an enzyme-linked immunosorbent assay (ELISA), which demonstrated simultaneous detection capability to 6 sulfonylureas; the detection limits ranged from 0.02 to 1.0 ng/mL, and recoveries were between 78.3% to 104.5%. Liquid chromatography with tandem mass spectrometry (LC-MS/MS) confirmed the reliability of the proposed ELISA, based on real samples. These results suggest that the proposed ELISA could be an ideal method for screening to monitor for illicit adulteration of sulfonylureas in functional pill products.

Broad-specific immunochromatography for simultaneous detection of various sulfonylureas in adulterated multi-herbal tea

Sulfonylureas (SUs) are a series of anti-diabetic drugs widely used for type 2 diabetes mellitus for clinic treat. However, it is often illegally adulterated in multi-herbal tea to improve the claimed anti-diabetic activity in recent years. In this study, a novel hapten was rationally designed, and a broad-specific monoclonal antibody (anti-SUs mAb) recognizing nine SUs was developed. This mAb was used to develop a colloidal gold lateral flow immunochromatographic assay (CG-LFIA). The anti-SUs mAb demonstrated half inhibitory concentration (IC₅₀) ranged from 0.15 ng/mL to 3.25 ng/ mL for nine SUs by ELISA. The cut-off value of developed CG-LFIA for nine SUs was from 3 to 100 ng/ mL for the spiked samples. LC-MS/MS confirmed the reliability of the new CG-LFIA. The results indicated that the proposed CG-LFIA could be an ideal method in on-site screening surveillance assay for SUs illegally adulterated in multi-herbal tea products.

A critical review on the availability of substandard and falsified medicines online: Incidence, challenges and perspectives

Simultaneous expansion of the Internet and increased globalisation of the pharmaceutical industry have meant medication can be accessed transnationally from both legal and illicit sources. This has coincided with the rise of substandard and falsified medicines (SFMs) online. These products fail to meet regulatory or quality standards and/or are constituted with substandard ingredients, causing undesired pharmacological effects, including possible injury and death. This review aimed to identify original research studies that examined characteristics of SFM online sales, attitudes towards purchasing medicines online and strategies to address this drug safety challenge. Keywords of ‘Substandard’ and ‘Falsified’/‘Counterfeit’ and ‘Medicines’/‘Drugs’ and ‘Online’/‘Internet’ were searched using Web of Knowledge and PubMed databases. Resulting literature, which satisfied the study’s inclusion criteria, was included in the review, and the findings from each paper were assessed. From an initial 185 literature articles, 7 were eligible according to the inclusion criteria to be reviewed. These articles identified studies testing SFMs purchased online, surveys of attitudes and knowledge about SFMs online, and website content analysis to detect illegal online sales. Challenges identified were lack of knowledge and awareness among consumers and physicians, in addition to the use of direct-to-consumer-advertising, via Internet platforms and social media, providing easy access to SFMs. Despite this, medicine authentication technology, website verification approaches and new detection methods were identified as potential solutions specific to online SFM sales. To address online sales of SFMs, more robust research, greater awareness/educational programmes, analytical detection methods and more stringent online global governance are required.

Preparation of polydopamine-coated, graphene oxide/Fe3 O4 - imprinted nanoparticles for selective removal of sulfonylurea herbicides in cereals

BACKGROUND

Sulfonylureas are potentially toxic broad-spectrum herbicides. They pose a persistent threat to food safety and the environment. It is therefore important to develop a rapid and efficient pretreatment and detection method to prevent their harmful effects on human health.

RESULTS

In the present work, a novel and highly selective absorbent for chlorosulfuron (CS) detection was prepared by the simple self-polymerization of dopamine on the surface of magnetic graphene oxide using a CS template. The resultant imprinted nanoparticles (MGO@PDA-MIPs) were characterized by transmission electron microscopy, X-ray diffraction, vibrating-sample magnetometry, thermogravimetric analysis, and nitrogen adsorption-desorption. The adsorption experiments demonstrated that the MGO@PDA-MIPs have excellent selectivity with regard to CS, with a high imprinting factor of 3.41 compared with a non-imprinted polymer. The nanoparticles rapidly achieve adsorption equilibrium and efficient desorption because there are numerous binding sites on the thin polydopamine imprinting layer. Under optimized conditions, the MGO@PDA-MIPs can be used to detect sulfonylurea residues in cereal samples by magnetic solid phase extraction coupled with high performance liquid chromatography (HPLC). The nanoparticles have a satisfactory recovery rate (80.65-101.01%) with a relative standard deviation (RSD) of less than 7.15%, and a limit of detection with regard to CS of 1.61 μg kg^-1 (S/N = 3). They can also be re-used at least seven times.

CONCLUSION

The MGO@PDA-MIPs have outstanding recognition performance, and can be prepared by a facile, single-step, and environmentally friendly process. They therefore have excellent potential for the recognition and separation of trace sulfonylurea herbicides in complex matrices. © 2020 Society of Chemical Industry.

Rapid detection of aflatoxin B1 by dummy template molecularly imprinted polymer capped CdTe quantum dots

A novel and sensitive fluorescent sensor was synthesized for the rapid and specific recognition of aflatoxin B₁ (AFB1) by our combining molecular imprinting techniques with quantum dot technology. Molecularly imprinted polymers coated CdTe quantum dots (MIP@CdTe QDs) were prepared through the Stöber method with 5,7-dimethoxycoumarin as a dummy template. 3-Aminopropyltriethoxysilane was selected as the functional monomer, and tetraethyl orthosilicate was used as the cross-linking agent. The best molar ratio of 5,7-dimethoxycoumarin to functional monomer to cross-linker was 4:20:15. The MIP@CdTe QD composites were characterized by Fourier transform infrared spectroscopy, transmission electron microscopy, and fluorescence spectroscopy. Under the optimum conditions, the relative fluorescence intensity of the MIP@CdTe QDs showed adequate linearity with AFB1 concentration over the range from 80 to 400 ng/g. The detection limit is 4 ng/g, according to 3s/K. Finally, the method was successfully applied to the quantitative determination of AFB1 in real samples. The spike recoveries at different spiking levels ranged from 99.20% to 101.78%, which were consistent with those measured by ultrahigh-performance liquid chromatography-mass spectrometry. The method developed for AFB1 detection lays the foundation for rapid detection of trace amounts of other exogenous harmful substances in a complicated matrix.