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- An Electrochemical Outlook on Tamoxifen Biotransformation: Current and Future ProspectsPublication . Garrido, Jorge; Garrido, E. Manuela; Oliveira-Brett, Ana Maria; Borges, FernandaTamoxifen is a nonsteroidal antiestrogen that is currently and widely used in the treatment of breast cancer in all of its stages, in adjuvant therapy as a long-term suppressant of tumor recurrence and also as a chemopreventive agent in women that are in high risk of developing this type of estrogen-dependent cancer. From a toxicological and (bio)analytical point of view the knowledge of the metabolic pathways of a drug is found to be extremely important. So, in the present work the most important tamoxifen biotransformation steps were reviewed in the light of recent pharmacological data. This overview also includes the current controversy concerning tamoxifen DNA-damaging (genotoxic) versus non-genotoxic mechanisms. A special focus will be given to the putative application of electrochemical methods as a modern and reliable analytical tool for determination of tamoxifen and its metabolites. Moreover, the potential of DNA electrochemical sensors for detection of structural damage to DNA as a basis for toxicity screening is highlighted. Future prospects looking for the importance of developing new analytical methodologies are also discussed.
- Carbon nanotube β-cyclodextrin-modified electrode for quantification of cocaine in seized street samplesPublication . Garrido, Jorge; Borges, F.; Brett, C. M. A.; Garrido, E. ManuelaDetection and quantification of cocaine is a key tool in fields such as police apprehensions and the fight against drug trafficking. Thus, a simple, fast and inexpensive electroanalytical methodology for the determination of cocaine in seized street samples has been developed, employing linear sweep voltammetry. The method is based on the use of a glassy carbon (GC) electrode modified by a combination of multi-walled carbon nanotubes (MWCNT) with β- cyclodextrin (β-CD) incorporated in a polyaniline film. The proposed method shows high reproducibility, repeatability and specificity. Under optimal conditions, the β-CD/ MWCNT-modified GC electrode gives a detection limit of 1.02 μM cocaine. The results obtained are in good agreement with those obtained by the high-performance liquid chromatography reference method. The new methodology proposed has excellent potential as the basis of a portable analytical sensor for on-site screening of cocaine in seized street samples.