Percorrer por autor "Castanheira, Elisabete M.S."
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- Magnetoliposomes as carriers for promising antitumor thieno[3,2-b]pyridin-7-arylamines: photophysical and biological studiesPublication . Rodrigues, Ana Rita O.; Almeida, Bernardo G.; Rodrigues, Juliana M.; Queiroz, Maria João R.P.; Calhelha, Ricardo C.; Ferreira, Isabel C.F.R.; Pires, A.; Pereira, André M.; Araújo, José Pedro; Coutinho, Paulo J.G.; Castanheira, Elisabete M.S.Magnetoliposomes containing superparamagnetic manganese ferrite nanoparticles were tested as nanocarriers for two new promising antitumor drugs, a N-(3-methoxyphenyl)thieno[3,2-b]pyridin-7-amine (1) and a N-(2-methoxy-phenyl)thieno[3,2-b] pyridin-7-amine (2). The fluorescence emission of both compounds was studied in different polar and non-polar media, evidencing a strong intramolecular charge transfer character of the excited state of both compounds. These in vitro potent antitumor thienopyridine derivatives were successfully incorporated in both aqueous and solid magnetoliposomes, with encapsulation efficiencies higher than 75%. The magnetic properties of magnetoliposomes containing manganese ferrite nanoparticles were measured for the first time, proving a superparamagnetic behaviour. Growth inhibition assays on several human tumor cell lines showed very low GI 50 values for drug-loaded aqueous magnetoliposomes, comparing in most cell lines with the ones previously obtained using the neat compounds. These results are important for future drug delivery applications using magnetoliposomes in oncology, through a dual therapeutic approach (simultaneous chemotherapy and magnetic hyperthermia).
- Magnetoliposomes based on magnetic/plasmonic nanoparticles loaded with tricyclic lactones for combined cancer therapyPublication . Rio, Irina S.R.; Rodrigues, Ana Rita O.; Rodrigues, Juliana M.; Queiroz, Maria João R.P.; Calhelha, Ricardo C.; Ferreira, Isabel C.F.R.; Almeida, Bernardo G.; Pires, Ana; Pereira, André M.; Araújo, João Paulo; Castanheira, Elisabete M.S.; Coutinho, Paulo J.G.Liposome-like nanoarchitectures containing manganese ferrite nanoparticles covered or decorated with gold were developed for application in dual cancer therapy, combining chemotherapy and photothermia. The magnetic/plasmonic nanoparticles were characterized using XRD, UV/Visible absorption, HR-TEM, and SQUID, exhibiting superparamagnetic behavior at room temperature. The average size of the gold-decorated nanoparticles was 26.7 nm for MnFe2 O4 with 5–7 nm gold nanospheres. The average size of the core/shell nanoparticles was 28.8 nm for the magnetic core and around 4 nm for the gold shell. Two new potential antitumor fluorescent drugs, tricyclic lactones derivatives of thienopyridine, were loaded in these nanosystems with very high encapsulation efficiencies (higher than 98%). Assays in human tumor cell lines demonstrate that the nanocarriers do not release the antitumor compounds in the absence of irradiation. Moreover, the nanosystems do not cause any effect on the growth of primary (non-tumor) cells (with or without irradiation). The drug-loaded systems containing the core/shell magnetic/plasmonic nanoparticles efficiently inhibit the growth of tumor cells when irradiated with red light, making them suitable for a triggered release promoted by irradiation.
- Magnetoliposomes containing calcium ferrite nanoparticles for applications in breast cancer therapyPublication . Pereira, Daniela S.M.; Cardoso, Beatriz D.; Rodrigues, Ana Rita O.; Amorim, Carlos O.; Amaral, Vítor S.; Almeida, Bernardo G.; Queiroz, Maria João R.P.; Martinho, Olga; Baltazar, Fátima; Calhelha, Ricardo C.; Ferreira, Isabel C.F.R.; Coutinho, Paulo J.G.; Castanheira, Elisabete M.S.Magnetoliposomes containing calcium ferrite (CaFe2O4) nanoparticles were developed and characterized for the first time. CaFe2O4 nanoparticles were covered by a lipid bilayer or entrapped in liposomes forming, respectively, solid or aqueous magnetoliposomes as nanocarriers for new antitumor drugs. The magnetic nanoparticles were characterized by UV/Visible absorption, XRD, HR-TEM, and SQUID, exhibiting sizes of 5.2 +/- 1.2 nm (from TEM) and a superparamagnetic behavior. The magnetoliposomes were characterized by DLS and TEM. The incorporation of two new potential antitumor drugs (thienopyridine derivatives) specifically active against breast cancer in these nanosystems was investigated by fluorescence emission and anisotropy. Aqueous magnetoliposomes, with hydrodynamic diameters around 130 nm, and solid magnetoliposomes with sizes of ca. 170 nm, interact with biomembranes by fusion and are able to transport the antitumor drugs with generally high encapsulation effciencies (>=70%). These fully biocompatible drug-loaded magnetoliposomes can be promising as therapeutic agents in future applications of combined breast cancer therapy.
- Properties and applications of PDMS for biomedical engineering: a reviewPublication . Miranda, Inês; Souza, Andrews Victor Almeida; Sousa, Paulo; Ribeiro, J.E.; Castanheira, Elisabete M.S.; Lima, Rui A.; Minas, GraçaPolydimethylsiloxane (PDMS) is an elastomer with excellent optical, electrical and mechanical properties, which makes it well-suitable for several applications such as microfluidic and pho-tonics in several areas. Due to its biocompatible feature, PDMS is widely used for biomedical purposes. This widespread led also to the massification of the soft-lithography technique, intro-duced for facilitating the rapid prototyping of micro and nanostructures using elastomeric ma-terials, most notably PDMS. This technique allowed advances on microfluidic, electronic and biomedical fields. In this review an overview of the PDMS properties and some of its commonly used treatments, aiming the suitability to those fields’ needs, are presented. Applications such as microchips in biomedical field, replication of cardiovascular flow and medical implants are also reviewed.
- Synthesis of the first thieno-δ-carboline. Fluorescence studies in solution and in lipid vesiclesPublication . Queiroz, Maria João R.P.; Castanheira, Elisabete M.S.; Pinto, Ana M.R.; Ferreira, Isabel C.F.R.; Begouin, Agathe; Kirsch, GilbertThe first thieno-δ-carboline (6,8,9-trimethyl-5H-pyrido[3,2-b]thieno[3,2-f]indole) was prepared in good yield (70%) by intramolecular palladium-assisted cyclization of an ortho-chlorodiarylamine. The latter was in turn selectively synthesized in high yield (90%) by C–N palladiumcatalyzed cross-coupling of 3-bromo-2-chloropyridine with, the also prepared, 6-amino-2,3,7-trimethylbenzo[b]thiophene. Fluorescence studies in solution show that thieno-δ-carboline has a solvatochromic behaviour. Despite the low fluorescence quantum yields in solution, studies of its incorporation in lipid vesicles of DPPC, DOPE and DODAB indicate that thienocarboline is located mainly inside the lipid bilayer, exhibiting different behaviours in gel or liquid-crystalline phases. Our studies are useful for the incorporation of thienocarboline in liposomes and for controlled drug release assays, due to its biological activity.