Johny P. Monteiro

Preparation and cytotoxicity of N,N,N-trimethyl chitosan/alginate beads containing gold nanoparticles

Polyelectrolyte complex beads based on N,N,N-trimethyl chitosan (TMC) and sodium alginate (ALG) were obtained. This biomaterial was characterised by FTIR, TGA/DTG, DSC and SEM analysis. The good properties of polyelectrolyte complex hydrogel beads were associated, for the first time, with gold nanoparticles (AuNPs). Through a straightforward methodology, AuNPs were encapsulated into the beads. The in vitro cytotoxicity assays on the Caco-2 colon cancer cells and healthy VERO cells showed that the beads presented good biocompatibility on both cell lines, whereas the beads loaded with gold nanoparticles (beads/AuNPs) was slightly cytotoxic on the Caco-2 and VERO cells.

Preparation and cytotoxicity of N-modified chitosan nanoparticles applied in curcumin delivery.

Nanoparticles (NPs) based on N,N-dimethyl chitosan (DMC) and N,N,N-trimethyl chitosan (TMC), physical crosslinked with sodium tripolyphosphate (TPP) were successful obtained, using water/benzyl alcohol emulsion system. NPs morphologies were evaluated by Scanning Electron Microscopy and Transmission Electron Microscopy. NPs were characterized by Infrared Spectroscopy (FTIR), Thermogravimetric Analysis, Zeta Potential, Differential Scanning Calorimetry and Wide-angle X-ray Scattering. Curcumin (CUR) was loaded onto NPs and controlled release studies were evaluated in simulated intestinal fluid and in simulated gastric fluid. Cytotoxicity assays showed only loaded TMC/TPP particles containing CUR were slightly cytotoxic on human cervical tumor cells (SiHa cells), concerning unloaded TMC/TPP particles. Conversely, loaded NPs (TMC/TPP/CUR and DMC/TPP/CUR), especially TMC/TPP/CUR sample presented greater biocompatibility toward healthy VERO cells than unloaded NPs (TMC/TPP and DMC/TPP).

Polyelectrolyte complex containing silver nanoparticles with antitumor property on Caco-2 colon cancer cells.

Polyelectrolyte complex (beads) based on N,N,N-trimethyl chitosan/alginate was successful obtained and silver nanoparticles (AgNPs) were loaded within beads. In vitro cytotoxicity assays using beads/silver nanoparticles (beads/AgNPs) provided results, indicating that this material significantly inhibited the growth of colon cancer cells (Caco-2). In vitro release studies showed that the beads stabilized AgNPs and repressed Ag(0) oxidation under gastric conditions (pH 2.0). On the other hand, at physiological condition (pH 7.4) the beads/AgNPs released 3.3 μg of Ag(+) per each beads milligram. These studies showed that the concentration of Ag(+) released (3.3 μg) was cytotoxic for the Caco-2 cells and was not cytotoxic on healthy VERO cells. This result opens new perspectives for the manufacture of biomaterials based on beads/AgNPs with anti-tumor properties.

Quantification of EPA and DHA in seafood of the south coast of Brazil

Purpose – The increase in seafood trade in recent years motivates more detailed studies of different species, as well as evaluation of the nutritional quality of their lipid content. Thus, the purpose of this paper is to evaluate the fatty acid composition, especially the concentrations and fractionation of omega‐3 essential fatty acid in classes of mussels (male and female), oysters, squid, and octopus captured on the south coast of Brazil.Design/methodology/approach – Fatty acid methyl esters were prepared by methylation of total lipids and were separated by gas chromatography. Quantification of LNA, AA, EPA, and DHA was done against tricosanoic acid methyl ester as an internal standard. Total lipids were fractionated into neutral lipids and polar lipids by classical column chromatography.Findings – The results of this study were as follows: the female mussel had the highest lipid content (3.52 per cent), followed by the male mussel (2.70 per cent), squid (1.05 per cent), octopus (0.79 per cent), and oy...

Incorporation of conjugated fatty acids into Nile tilapia (Oreochromis niloticus)

BACKGROUND The aim of this work was to improve the nutritional quality of Nile tilapia meat through enriched diets with conjugated isomers of linolenic acid from tung oil. The transfer process of conjugated fatty acids (CFAs) into fish muscle tissue was evaluated by gas chromatography-flame ionization detection (GC-FID) and easy ambient sonic-spray ionization mass spectrometry (EASI-MS). RESULTS The results showed that conjugated fatty acids were transferred from enriched diet for muscle tissue of Nile tilapia. Conjugated linoleic acids biosynthesis from conjugated linolenic acids was also observed after 10 days. Other important fatty acids such as docosahexaenoic (DHA), eicosapentaenoic (EPA) and arachidonic (AA) acids were also identified over time; however, DHA showed the highest concentration when compared with EPA and AA compounds. CONCLUSION Therefore, the nutritional quality of Nile tilapia was improved through feeding with enriched diets. The ingestion of these fish may contribute to reaching adequate levels of daily CFA consumption. Furthermore, other important substances which play an important role in human metabolism, such as EPA, DHA and AA, can also be ingested together with CFA.

Smart hydrogel beads with potential therapeutic target in Caco-2 colon cancer cells.

drug. An initial burst effect of the free DFOwas observed with a second burst of the encapsulated drug after the addition of a hyperthermic pulse. Hence, this formulation could circumvent the off-target effects of systemic delivery, while enabling facile control of sustainable release in a minimally invasive manner. Precisely controlling drug release in this way may enhance efficacy at the target site with minimal side effects.

Síntese e caracterização de nanobastões de ouro para aplicação em biossensores plasmônicos

Nanoparticulas de ouro (AuNPs) apresentam efeito de ressonância de plasmon de superficie localizado (LSPR), fenomeno gerado sobre o ouro nanoestruturado por meio da incidencia de luz em uma interface metal/dieletrico. Por consequencia disso as AuNPs vem sendo amplamente empregadas no desenvolvimento de biossensores as quais apresentam inumeras vantagens quando comparados aos metodos convencionais de bionalise, como rapidez, simplicidade e portabilidade. E possivel obter nanoparticulas de ouro em diferentes formas geometricas as quais podem propiciar o desenvolvimento de biossensores com caracteristicas distintas em termos de desempenho e aplicabilidade. Neste contexto, o presente trabalho visou a sintese e caracterizacao nanobastoes de ouro (AuNRs) utilizando o metodo de crescimento mediado por sementes. Para isto aplicou-se diferentes volumes de solucoes de AgNO 3 e acido ascorbico (AA) durante a sintese, com o proposito de avaliar a influencia destes nas caracteristicas dos AuNRs produzidos. Alem disso, foi realizada a imobilizacao de AuNRs sobre substrato de vidro por meio da ativacao da sua superficie com (3mercaptopropil)trimetoxisilane. O intuito foi obter uma camada de nanobastoes sobre um substrato plano e transparente para posterior aplicacao como dispositivo plasmonico. Analises opticas e microscopicas foram usadas a fim de avaliar os materiais obtidos. Espectros de absorcao e imagens eletronicas mostraram que o melhor material foi produzido com uma sintese utilizando 100 µL de solucao 0,01 mol L -1 de AgNO3 e 30 µL de solucao 0,1 mol L -1 de AA. Nessas, foram obtidas morfologias de bastao mais homogenea e bandas de absorcao melhores definidas (caracteristicas requeridas para aplicacao em dispositivos plasmonicos).