Ready-to-use 3D-printed electrochemical cell for in situ voltammetry of immobilized microparticles and Raman spectroscopy.

We report in this communication a ready-to-use fused deposition modeling (FDM) based 3D-printed spectroelectrochemical cell to perform for the first time voltammetry of immobilized microparticles (VIMP) and Raman spectroscopy in situ using acrylonitrile butadiene styrene (ABS) as the filament material for printing. The 3D-printed cell was applied to evaluate solid state electrochemical behavior of tadalafil as a proof-of-concept. Several advantages were achieved in the use of the developed device, such as less manipulation of the working electrode, monitoring the same region of the solid microparticles before and after electrochemical measurements, better control of the laser incidence, low-cost and low-time production. Furthermore, the device was printed in a single-step, without handling to assembly and it has an estimated material cost of approximately 2 $. The use of 3D-printing technology was significantly important to integrate Raman spectroscopic method with VIMP measurements and to support mechanism elucidation and characterization of the compounds with less manipulation of the working electrode, avoiding loss of solid products formed from electrochemical reactions.

Microchip Electrophoresis Containing Electrodes for Integrated Electrochemical Detection.

Microchip electrophoresis is a versatile separation technique. Electrochemical detection is suitable to apply to microdevices due to its easy integration to the fabrication process and good sensitivity and selectivity. Here we describe the procedures to prepare Pt band electrodes deposited on glass to couple to polydimethylsiloxane (PDMS) microchips aiming the separation and detection of nitrite using an isolated potentiostat.

Some triterpenic compounds in extracts of Cecropia and Bauhinia species for different sampling years

ABSTRACT The aim of this paper is to provide an overview on the chemical composition of triterpenes in widespread used folk medicine species, through the development and validation of eleven compounds using HPLC-UV detection. The compounds were separated using isocratic elution, on a reverse phase column (Kinetex C18, 250 mm × 4.6 mm, 5 µm) with mobile phase consisted of acetonitrile:tetrahydrofuran (90:10, v/v), flow-rate of 0.5 ml/min and detection in 210 nm. Diverse validation parameters were successfully evaluated. The samples of Bauhinia variegata L., B. variegata var. candida Voigt, Fabaceae, Cecropia palmata Willd. and C. obtusa Trécul, Urticaceae, collected in 2012, 2013 and 2014 from Amazon were treated with two different solvents (ethyl acetate and chloroform) and analyzed by the proposed method. Stigmasterol, lupeol, β-sitosterol, β-amirin and α-amirin were found in all the studied plants. Highlighting the presence of oleanolic acid, maslinic acid in C. obtusa and C. palmata extracts, erythrodiol only in C. palmata, stigmasteol in B. variegata and α-amirin in B. variegata var. candida. Overall, ethyl acetate showed better performance as the extractor solvent than chloroform. Moreover, it could be used for the quality control of medicinal plants and to assess potential marker compounds.

Methionine stimulates motor impairment and cerebellar mercury deposition in methylmercury-exposed mice.

Methylmercury (MeHg) is a highly toxic environmental contaminant that produces neurological and developmental impairments in animals and humans. Although its neurotoxic properties have been widely reported, the molecular mechanisms by which MeHg enters the cells and exerts toxicity are not yet completely understood. Taking into account that MeHg is found mostly bound to sulfhydryl-containing molecules such as cysteine in the environment and based on the fact that the MeHg-cysteine complex (MeHg-S-Cys) can be transported via the L-type neutral amino acid carrier transport (LAT) system, the potential beneficial effects of L-methionine (L-Met, a well known LAT substrate) against MeHg (administrated as MeHg-S-Cys)-induced neurotoxicity in mice were investigated. Mice were exposed to MeHg (daily subcutaneous injections of MeHg-S-Cys, 10 mg Hg/kg) and/or L-Met (daily intraperitoneal injections, 250 mg/kg) for 10 consecutive days. After treatments, the measured hallmarks of toxicity were mostly based on behavioral parameters related to motor performance, as well as biochemical parameters related to the cerebellar antioxidant glutathione (GSH) system. MeHg significantly decreased motor activity (open-field test) and impaired motor performance (rota-rod task) compared with controls, as well as producing disturbances in the cerebellar antioxidant GSH system. Interestingly, L-Met administration did not protect against MeHg-induced behavioral and cerebellar changes, but rather increased motor impairments in animals exposed to MeHg. In agreement with this observation, cerebellar levels of mercury (Hg) were higher in animals exposed to MeHg plus L-Met compared to those only exposed to MeHg. However, this event was not observed in kidney and liver. These results are the first to demonstrate that L-Met enhances cerebellar deposition of Hg in mice exposed to MeHg and that this higher deposition may be responsible for the greater motor impairment observed in mice simultaneously exposed to MeHg and L-Met.