HPTLC sequentially coupled to UV and SERS: A cost-effective tool for confirmative identification and quantitation of sildenafil in falsified herbal products.

The detection of falsified drugs usually requires multi-disciplinary analysis for confirmative identification. Among hyphenated techniques with high specificity detection, thin-layer chromatography coupled with surface-enhanced Raman spectroscopy (TLC-SERS) is an efficient choice, especially for herbal products with diversified matrix. In this study, HPTLC was coupled to two detection techniques: UV absorption and Raman scattering with silver colloid enhancement for the analysis of sildenafil adulterated in herbal products.

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.

Detection of sildenafil adulterated in herbal products using thin layer chromatography combined with surface enhanced Raman spectroscopy: "Double coffee-ring effect" based enhancement.

Sildenafil is an inhibitor of the phosphodiesterase type 5 which is commonly adulterated in herbal health products. In this study, a rapid, sensitive and selective method using thin layer chromatography (TLC) combined with surface-enhanced Raman spectroscopy (SERS) was developed for identification of sildenafil adulteration in herbal drugs and dietary supplements. TLC separation method was developed and different SERS factors were investigated: nanosilver colloid preparation, concentration and volume, and coffee-ring effect (CRE) enhancement for SERS measurement.

Development of FeO/Ag core/shell-based multifunctional immunomagnetic nanoparticles for isolation and detection of CD34+ stem cells.

FeO/Ag core/shell nanoparticles functionalized with the free amino (NH) functional groups (FeO/Ag-NH) were conjugated with fluorescent electron coupled dye (ECD)-antiCD34 antibody using the 1-ethyl-3-(3'-dimethyl-aminopropyl) carbodiimide (EDC) catalyst (ECD - Electron Coupled Dye or R Phycoerythrin-Texas Red is a fluorescent organic dye attached to the antibody). The characteristic fluorescence of ECD in the antibody was investigated and was used as a good indicator for estimating the percentage of the antibodies that were successfully conjugated with the nanoparticles. The conjugation efficiency was found to increase depending on the V:V ratio, where V and V are the volumes of the nanoparticle solution (concentration of 50 ppm) and the as-purchased antibody solution, respectively.

Fabrication and vibration characterization of curcumin extracted from turmeric (Curcuma longa) rhizomes of the northern Vietnam.

In this report, we present the research results on using the conventional method and microwave technology to extract curcuminoid from turmeric roots originated in different regions of Northern Vietnam. This method is simple, yet economical, non-toxic and still able to achieve high extraction performance to get curcuminoid from turmeric roots. The detailed results on the Raman vibration spectra combined with X-ray powder diffraction and high-performance liquid chromatography/mass spectrometry allowed the evaluation of each batch of curcumin crystalline powder sample received, under the conditions of applied fabrication technology.