Rapid detection of six phosphodiesterase type 5 enzyme inhibitors in healthcare products using thin-layer chromatography and surface enhanced Raman spectroscopy combined with BP neural network

Artificial Intelligence for Surface-Enhanced Raman Spectroscopy

Surface-enhanced Raman spectroscopy (SERS), well acknowledged as a fingerprinting and sensitive analytical technique, has exerted high applicational value in a broad range of fields including biomedicine, environmental protection, food safety among the others. In the endless pursuit of ever-sensitive, robust, and comprehensive sensing and imaging, advancements keep emerging in the whole pipeline of SERS, from the design of SERS substrates and reporter molecules, synthetic route planning, instrument refinement, to data preprocessing and analysis methods. Artificial intelligence (AI), which is created to imitate and eventually exceed human behaviors, has exhibited its power in learning high-level representations and recognizing complicated patterns with exceptional automaticity. Therefore, facing up with the intertwining influential factors and explosive data size, AI has been increasingly leveraged in all the above-mentioned aspects in SERS, presenting elite efficiency in accelerating systematic optimization and deepening understanding about the fundamental physics and spectral data, which far transcends human labors and conventional computations. In this review, the recent progresses in SERS are summarized through the integration of AI, and new insights of the challenges and perspectives are provided in aim to better gear SERS toward the fast track.

Thin layer chromatography coupled with surface enhanced Raman scattering for rapid separation and on-site detection of multi-components

The separation and detection of multi-component mixtures has always been a challenging task. Traditional detection methods often suffer from complex operation, high cost, and low sensitivity. Surface enhanced Raman scattering (SERS) technique is a high sensitivity, powerful and rapid detection tool, which can realize the specific detection of single substance components, but it must solve the problem that multi-component mixtures cannot be accurately determined. Thin layer chromatography (TLC) technology, as a high-throughput separation technology, uses chromatographic plate as the stationary phase, and could select different developing phases for separation experiments. The advantages of TLC technology in short distance and rapid separation are widely used in protein, dye and biomedical fields. However, TLC technology has limitations in detection ability and difficulty in obtaining ideal signal intensity. The combination of TLC technology and SERS technology made the operation procedure simple and the sample size small, which can achieve rapid on-site separation and quantitative detection of mixtures. Due to the rapid development of TLC-SERS technology, it has been widely used in the investigation of various complex systems. This paper reviews the application of TLC-SERS technology in food science, environmental pollution and biomedicine.

Single versus Double Coffee-Ring Effect Patterns in Thin-Layer Chromatography Coupled with Surface-Enhanced Raman Spectroscopic Analysis of Anti-Diabetic Drugs Adulterated in Herbal Products

In thin-layer chromatography coupled with surface-enhanced Raman spectroscopy (TLC-SERS), the coffee ring effect (CRE) describes the formation of a ring-shape spot (blank in the middle and darker on the edge) caused by the aggregation of silver nanoparticles (Ag NPs), alone (single CRE) or with the analytes (double CRE). In this work, the SCRE and DCRE were investigated in two anti-diabetic drugs, hydrophobic glibenclamide (GLB) and more hydrophilic metformin (MET). The SCRE occurred in GLB analysis, as opposed to the DCRE that occurred in MET. It was proven that for optimization of the TLC-SERS analytical procedure, it is necessary to distinguish the CRE patterns of analytes. Additionally, MET and GLB were analyzed with the developed TLC-SERS method and confirmed by another validated method using high-performance liquid chromatography. Four herbal products collected on the market were found to be adulterated with GLB or/and MET; among those, one product was adulterated with both MET and GLB, and two products were adulterated with GLB at a higher concentration than the usual GLB prescription dose. The TLC-SERS method provided a useful tool for the simultaneous detection of adulterated anti-diabetic herbal products, and the comparison of the SCRE and DCRE provided more evidence to predict CRE patterns in TLC-SERS.

A Comprehensive Review on Analytical Techniques for Determination of Sex Stimulants, PDE5 Inhibitors in Different Matrices with Special Focus on the Electroanalytical Methods

Erectile dysfunction (ED) is one of the most common chronic diseases affecting men and its incidence increases with aging. Due to its substantial influence on the quality of life, phosphodiesterase type-5 (PDE5) inhibitors have been implemented to treat ED by increasing the penile blood flow that results in improving erection. PDE5 inhibitors is a class of drugs that affects many pharmacological sectors, and it is essential to review the different analytical methods described for their determination. Few reviews were published concerning this group of drugs. For this reason, this review article gathers the different analytical methods used to determine PDE5 inhibitors in pharmaceutical and biological samples over the past 20 years. Different analytical techniques were used to analyze these compounds in different matrices such as separation methods (capillary electrophoresis, LC-MS, UPLC-MS/MS, and GC-MS), spectroscopic methods (UV-visible methods, FT-IR spectroscopy and spectrofluorometry) and electrochemical methods (polarography, voltammetry and potentiometry). This review focuses on the different electrochemical methods and their use in analytical determination of PDE5 inhibitors in pharmaceutical dosage forms and biological samples. Moreover, it discusses the different modified electrodes used for their electroanalytical determination and the behavior of the studied drugs at different modified electrodes. Additionally, this review discusses the pharmacokinetics of the studied compounds and their interactions with other co-administered drugs especially the metabolic interactions between the studied compounds and other co-administered drugs in different matrices. This literature survey would provide a beneficial guide for future analytical investigation of PDE5 inhibitors.

Cytochrome P450 3A4-mediated pharmacokinetic interaction study between tadalafil and canagliflozin using high-performance thin-layer chromatography

Diabetes is a known risk factor for sexual dysfunction in men; diabetic men have an increased risk of erectile dysfunction compared to non-diabetic men. Canagliflozin is one of the common antidiabetic drugs that is readily used in the treatment of type-2 diabetes. Concomitantly phosphodiesterase 5 inhibitors, such as tadalafil, can be given to the patient to alleviate erectile dysfunction. Canagliflozin is reported to be one of the cytochrome P450 3A4 enzyme inhibitors, that might seriously influence blood concentration levels of tadalafil but there is no study till now, discussing this interaction. Therefore, a fast, simple, and sensitive high-performance thin-layer chromatographic method was developed, validated, and applied for the simultaneous determination of tadalafil and canagliflozin in spiked and real human plasma. The limit of detection for tadalafil was 0.14 ng/band and for canagliflozin was 0.16 ng/band. The limit of quantitation value for tadalafil was 0.43 ng/band and for canagliflozin was 0.47 ng/band. Tadalafil and canagliflozin were determined simultaneously in real human plasma using the described procedure and the method was applied for in vivo pharmacokinetic drug interaction study between the studied drugs, which proved significant interaction between them when administered simultaneously.

Fluorescence polarisation for high-throughput screening of adulterated food products via phosphodiesterase 5 inhibition assay

The surge in the consumption of food products containing herbal aphrodisiacs has driven their widespread adulteration. A rapid screening strategy is, therefore, warranted to curb this problem. This study established an enzyme inhibition assay to screen phosphodiesterase 5 (PDE5) inhibitors as adulterants in selected food products. Fluorescein-labelled cyclic-3',5'-guanosine monophosphate was utilised as substrates for the PDE5A1 enzyme, aided by the presence of nanoparticle phosphate-binding beads on their fluorescence polarisation. The sample preparation was optimised to improve the enzyme inhibition efficiency and applied to calculate the threshold values of six blank food matrices. The assay was validated using sildenafil, producing an IC₅₀ of 4.2 nM. The applicability of the assay procedure was demonstrated by screening 55 distinct food samples. The results were subsequently verified using confirmatory liquid chromatography-high-resolution mass spectrometry (LC-HRMS) analysis. Altogether, 49 samples inhibited the PDE5 enzyme above the threshold values (75.7%-105.5%) and were registered as potentially adulterated samples. The remaining six samples were marked as nonadulterated with percentage inhibition below the threshold values (-3.3%-18.2%). The LC-HRMS analysis agreed with the assay results for all food products except for the instant coffee premix (ICP) samples. False-positive results were obtained for the ICP samples at 32% (8/25), due to possible PDE5 inhibition by caffeine. Contrarily, all other food samples were found to produce 0% (0/30) false-positive or false-negative results. The broad-based assay, established via a simple mix-incubate-read format, exhibited promising potential for high-throughput screening of PDE5 inhibitors in various food products, except those with naturally occurring phosphodiesterase inhibitors such as caffeine.

Interpol review of controlled substances 2016-2019

This review paper covers the forensic-relevant literature in controlled substances from 2016 to 2019 as a part of the 19th Interpol International Forensic Science Managers Symposium. The review papers are also available at the Interpol website at: https://www.interpol.int/content/download/14458/file/Interpol%20Review%20Papers%202019.pdf.

Thin-layer chromatography combined with surface-enhanced Raman scattering for rapid detection of benzidine and 4-aminobiphenyl in migration from food contact materials based on gold nanoparticle doped metal-organic framework

In this work, a rapid and sensitive thin-layer chromatography combined with surface-enhanced Raman spectroscopy method was established for rapid detection of benzidine and 4-aminobiphenyl in migration from food contact materials based on Au nanoparticle doped metal-organic framework. Benzidine and 4-aminobiphenyl were firstly separated by thin-layer chromatography to solve the limitation of their overlapping Raman peaks. Then the target molecules were monitored by adding AuNPs/MIL-101(Cr) on the sample spots. Under the optimum conditions, the concentration of benzidine and 4-aminobiphenyl can be quantitatively measured in the range of 2.0-20.0 and1.0-15.0 μg/L, respectively with good linear relationship, and the limits of detection were 0.21 and 0.23 μg/L, respectively. Furthermore, the developed method was applied to analyze benzidine and 4-aminobiphenyl in migration of different food contact materials. The recoveries of benzidine and 4-aminobiphenyl for migration of food contact materials, including paper cups, polypropylene food containers, and polyethylene glycol terephthalate bottles, were 80.6-116.0 and 80.7-118% with relative standard deviations of 1.1-9.1 and 3.1-9.9%, respectively. Surface-enhanced Raman scattering detection was performed conveniently in the on-plate mode without additional elution process. The method shows great potential in rapid monitoring of hazardous substances with overlapping characteristic Raman peaks in food contact materials.

Simultaneous analysis of 23 illegal adulterated aphrodisiac chemical ingredients in health foods and Chinese traditional patent medicines by ultrahigh performance liquid chromatography coupled with quadrupole time-of-flight mass spectrometry

This paper presents an application of ultra high-performance liquid-chromatography-quadrupole-TOF high resolution mass spectrometry (UHPLC-Q-TOF HRMS) for simultaneous analysis of 23 illegal adulterated aphrodisiac type chemical ingredients in health foods and Chinese Traditional Patent Medicines (CTPMs). The mass spectrometer was operated in Information Dependent Acquisition (IDA) mode, which provides crucial information for the elemental composition analysis, structure elucidation and quantitative analysis simultaneously. Quantitative analysis was performed using the peak areas of the precursor ions in the XICs. The method validation included assessment of selectivity, sensitivity, calibration curve, accuracy, precision, recovery, matrix effect and stability. The results show good linear relationship with the concentrations of the analytes over wide concentration ranges (e.g., 0.05–10 μg/g for sildenafil) as all the fitting coefficients of determination r² are >0.9984. The detection limits (LODs) were in the range of 0.002–0.1 μg/g. The recoveries were able to reach 82.5–103.6%, while the matrix effects ranged from 87.7 to 109.3%. The intra- and inter-day accuracies were in the range of 82.3–113.8%, while the intra- and inter-day precision ranged from 0.4 to 13.6%. Among 40 batches of health foods and 32 batches of CTPMs (including 28 capsules, 32 tablets, 10 liquid and 2 pills) samples, 28 batches of heath foods were positive. The detected chemical ingredients involved sildenafil, tadalafil, aildenafil and sulfoaildenafil. This method can be used for the screening, identification and quantification of illegal adulterated aphrodisiac chemical ingredients in health foods and CTPMs. Moreover, the LC-Q-TOF MS is very useful to structural elucidation of unknown compound.

Rapid detection of hexamethylenetetramine based on the substrate UC@SiO2@Au@Ag using SERS

UC@SiO₂@Au@Ag was employed for the first time as a SERS substrate to detect HMT.