Browsing by Author "Cagide, Fernando"
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- Bonding to Psychedelics: Synthesis of Molecularly Imprinted Polymers Targeting 4-Bromo-2,5-dimethoxyphenethylamine (2C-B)Publication . Martins, Daniel; Fernandes, Carlos; Mendes, Ricardo F.; Cagide, Fernando; Silva, António Fernando; Borges, Fernanda; Garrido, Jorge; Garrido, JorgeThe increasing interest in utilizing psychedelics for therapeutic purposes demands the development of tools capable of efficiently monitoring and accurately identifying these substances, thereby supporting medical interventions. 4-Bromo-2,5-dimethoxyphenethylamine (2C-B) has gained significant popularity as one of the most widely used psychedelic compounds in non-medical settings. In this study, we aimed to create a material with selective recognition of 2C-B by synthesizing a series of molecularly imprinted polymers (MIP) using 2C-B as the template and varying ratios of methacrylic acid (MAA) as the functional monomer (1:2, 1:3, and 1:4). Both thermal and microwave-assisted polymerization processes were employed. The molar ratio between the template molecule (2C-B) and functional monomer (MAA) was 1:4, utilizing a microwave-assisted polymerization process. Isotherm studies revealed a Langmuir’s maximum absorption capacity (Bmax) value of 115.6 μmol·mg−1 and Kd values of 26.7 μM for this material. An imprint factor of 4.2 was determined for this material, against the corresponding non-imprinted polymer. The good selectivity against 14 other new psychoactive substances highlighted the material’s potential for applications requiring selective recognition. These findings can contribute to the development of tailored materials for the detection and analysis of 2C-B, supporting advancements in non-medical use monitoring and potential therapeutic models involving psychedelics.
- Electrochemical sensing of the thyroid hormone thyronamine (T0AM) via molecular imprinted polymers (MIPs)Publication . Pacheco, João; Rebelo, Patrícia; Cagide, Fernando; Gonçalves, Luís Moreira; Borges, Fernanda; Rodrigues, José António; Delerue-Matos, CristinaRecent studies have shown that besides the well-known T3 (triiodothyronine) and T4 (thyroxine) there might be other important thyroid hormones, in particular T0AM (thyronamine) and T1AM (3-iodothyronamine). The absence of a large number of studies showing their precise importance might be explained by the limited number of analytical methodologies available. This work aims to show an electroanalytical alternative making use of electropolymerized molecularly imprinted polymer (MIPs). The MIPs' polymerization is performed on the surface of screen-printed carbon electrodes (SPCEs), using 4-aminobenzoic acid (4-ABA) as the building and functional monomer and the analyte T0AM as the template. The step-by-step construction of the SPCE-MIP sensor was studied by cyclic voltammetry (CV) and by electrochemical impedance spectroscopy (EIS). After optimization, by means of square-wave voltammetry, the SPCE-MIP showed suitable selectivity (in comparison with other thyroid hormones and catechol amines), repeatability (intra-day of 3.9%), a linear range up to 10 μmol L-1 (0.23 × 103 μg dL-1) with an r2 of 0.998 and a limit of detection (LOD) and quantification (LOQ) of 0.081 and 0.27 μmol L-1 (1.9 and 6.2 μg dL-1), respectively.
- Host-guest complexes of phenoxy alkyl acid herbicides and cyclodextrins. MCPA and β-cyclodextrinPublication . Garrido, E. Manuela; Santos, Marcos; Silva, Paulo; Cagide, Fernando; Garrido, J.M.P.J.; Borges, FernandaThe chlorophenoxy herbicideMCPA(4-chloro-2-methylphenoxyacetic acid), widely used for the control of broad-leafweeds primarily in cereal and grass seed crops, still remains one of the most often used herbicides in Portugal. As the formation of inclusion complexes with cyclodextrins can improve its solubility properties, the interaction between the herbicide MCPA and β-cyclodextrin was investigated. The stability constants describing the extent of formation of the complexes have been determined by phase-solubility studies. Different analytical techniques [ultraviolet-visible spectroscopy (UV-Vis), differential scanning calorimetry (DSC), Fourier transform infrared spectroscopy (FTIR), proton nuclear magnetic resonance spectroscopy (1H NMR)] were employed for a thorough investigation of the structural characteristics of the obtained complexes, which exhibited distinct features and properties from both “guest” and “host” molecules. FTIR and 1H NMR data obtained for the MCPA/β-CD complexes gave information about the interaction between MCPA and the nonpolar cyclodextrin cavity. The dramatic change observed in band frequency and proton displacements of OCH2 group and H6 aromatic proton confirmed the inclusion of MCPA in β-CD. The formation of an inclusion complex between MCPA and β-CD increased the aqueous solubility of this herbicide which could be a particularly advantageous property for some specific applications, namely to improve commercial formulation and for environmental protection.
- Microencapsulation of herbicide MCPA with native beta-cyclodextrin and its methyl and hydroxypropyl derivatives: An experimental and theoretical investigationPublication . Garrido, Jorge; Cagide, Fernando; Melle-Franco, Manuel; Borges, Fernanda; Garrido, E. ManuelaWhen a pesticide is released into the environment, most of it is lost before it reaches its target. An effective way to reduce environmental losses of pesticides is by using controlled release technology. Microencapsulation becomes a promising technique for the production of controlled release agricultural formulations. In this work, the microencapsulation of chlorophenoxy herbicide MCPA with native b-cyclodextrin and its methyl and hydroxypropyl derivatives was investigated. The phase solubility study showed that both native and b-CD derivatives increased the water solubility of the herbicide and inclusion complexes are formed in a stoichiometric ratio of 1:1. The stability constants describing the extent of formation of the complexes have been determined by phase solubility studies. 1H NMR experiments were also accomplished for the prepared solid systems and the data gathered confirm the formation of the inclusion complexes. 1H NMR data obtained for the MCPA/CDs complexes disclosed noticeable proton shift displacements for OCH2 group and H6 aromatic proton of MCPA provided clear evidence of inclusion complexation process, suggesting that the phenyl moiety of the herbicide was included in the hydrophobic cavity of CDs. Free energy molecular mechanics calculations confirm all these findings. The gathered results can be regarded as an essential step to the development of controlled release agricultural formulations containing herbicide MCPA.