RESUMEN
The high consumption of dietary supplements was a fundamental driver for the creation of the regulatory framework by the Brazilian governmental authorities. However, the regulatory agencies lack official low-cost methodologies to evaluate the quality of food supplements. A preliminary screening method by HPLC-DAD was proposed and validated for screening and quantification of adulterants in dietary supplements. The limits of detection and quantification were <0.11 and 0.37 µg.g-1, respectively. The method was applied for the investigation of ten unauthorized substances (spironolactone, hydrochlorothiazide, furosemide, clenbuterol, testosterone, testosterone propionate, yohimbine, vardenafil, tadalafil, and sildenafil) with a time of analysis of <5 min. Sixteen percent of the 44 samples analyzed had at least one adulterant at or above therapeutic concentrations. Subsequently, in vitro evaluations were performed of the potential cytotoxicity to evaluate the cell viability, DNA damage, determination of nitric oxide levels, and quantification of reactive oxygen species. Despite the necessity of further studies, the results indicate a relationship between the presence of adulterants in food supplements and a potential cytotoxic effect.
RESUMEN
The fabrication of microfluidic devices through fused deposition modeling (FDM) 3D printing has faced several challenges, mainly regarding obtaining microchannels with suitable transparency and sizes. Thus, the use of this printing system to fabricate microdevices for analytical and bioanalytical applications is commonly limited when compared to other printing technologies. However, for the first time, this work shows a systematic study to improve the potential of FDM 3D printers for the fabrication of transparent microfluidic devices. Several parameters and printing characteristics were addressed in both theoretical and experimental ways. It was found that the geometry of the printer nozzle plays a significant role in the thermal radiation effect that limits the 3D printing resolution. This drawback was minimized by adapting an airbrush tip (0.2 mm orifice diameter) to a conventional printer nozzle. The influence of the height and width of the extruded layer on the resolution and transparency in 3D-printed microfluidic devices was also addressed. Following the adjustments proposed, microchannels were obtained with an average width of around 70 µm ± 11 µm and approximately 80% visible light transmission (for 640 µm thickness). Therefore, the reproducibility and resolution of FDM 3D printing could be improved, and this achievement can expand the capability of this printing technology for the development of microfluidic devices, particularly for analytical applications.