Andrea Cecilia Dorion Rodas

This study examined the effect of graphene oxide (GO) film coatings, obtained via surface acoustic wave (SAW) atomization, on in vitro fibroblast proliferation on glass and gold-coated glass substrates, compared with optimal reference conditions in tissue culture-treated (TC-treated) plates. Fibroblast monolayers (FM) were cultured on GO-modified and unmodified substrates. Proliferation curves were analyzed using a linear approximation of the logistic equation (LE) over the time interval following initial adhesion. This approach enables quantitative evaluation of proliferation kinetics in the low-density regime, focusing on substrate-cell interactions where collective effects may be treated as a small parameter. The growth rate and carrying capacity of the logistic growth were determined for the reference condition, glass and gold substrates, and thin and thick GO films. TC-treated plates exhibited the highest initial cell density, whereas bare substrates showed reduced values. GO deposition systematically enhanced cell attachment, with thicker films restoring the growth rate and carrying capacity to near-reference levels. Thinner GO films and bare substrates showed reduced proliferation. Carrying capacity was highest for the reference condition and thicker GO films, indicating negligible growth limitation within the experimental timeframe, and lower for thinner films and bare substrates, consistent with inhibitory effects of mechanically stressed microenvironments. GO films, obtained via SAW atomization, effectively passivate glass and gold surfaces, enhancing substrate biocompatibility by increasing surface hydrophilicity, enabling their use in lab-on-chip platforms and related microfabricated biological devices. The proposed linear model successfully captures early-stage proliferation kinetics and isolates substrate-mediated effects, providing more precise values for the growth rate parameter.

Plinia edulis, popularly known as ‘cambucá’, is used in Brazilian folk medicine to treat several conditions. The aim of this study was to evaluate the mutagenicity and cytotoxicity of cambucá leaf extract, as well as its antioxidant activity. The ‘Ames’ test and Orac assay were used to evaluate the mutagenicity and antioxidant activity, respectively, and the phytochemical analysis of the ethanol leaf extract (LE) was performed by chromatographic and spectrometric methods. The in vitro cytotoxicity was tested on CHO (Chinese Hamster Ovary) cells and on nine human tumor cell lines. Phytochemical analysis of LE has revealed the presence of triterpenes and flavonoids. The LE did not show mutagenicity at the concentration of 20 mg plate-1 and exhibited high antioxidant activity, with Orac value of 3948 µmol TE g-1. The LE and its fractions (ethyl acetate; methanol) showed antiproliferative activity against cancer cell lines and proliferative activity in normal cells. The ethyl acetate fraction was the most active extract, presenting antiproliferative activity against strains of breast cancer, prostate cancer, colon cancer, lung cancer, melanoma and leukemia (GI50 0.01-8.57 µg mL-1), being more effective than the reference drug (doxorubicin) against human breast adenocarcinoma MCF-7 cell line. These results suggest P. edulis as a potential adjuvant in cancer therapy and chemoprevention.

RESUMO Os hidrogéis, redes poliméricas reticuladas capazes de absorver e reter uma grande quantidade de água devido à sua natureza hidrofílica, chamam a atenção para aplicações na Engenharia Tecidual. Ainda, esses materiais oferecem o potencial de projetar arcabouços partindo do seu comportamento pseudoplástico, o que é fundamental para impressão tridimensional (3D) baseada em extrusão. A adição de Laponita, um nanosilicato bidimensional em forma de disco, permite modificar o comportamento reológico de alguns géis, criando uma condição otimizada. Neste estudo, foi realizada a caracterização reológica do hidrogel compósito PEG-Laponita-alginato (PL-Alg) e de seu gel precursor PEG-Laponita (PL), visando futuramente a bioimpressão 3D. Inicialmente, foi avaliado o comportamento reológico de diferentes concentrações de Laponita no compósito PL. Verificou-se que a viscosidade da solução de PEG aumentou drasticamente como uma função da adição de Laponita, de modo que se observou um comportamento reológico não-Newtoniano fortemente pseudoplástico. O efeito dos diferentes teores de Laponita também pode ser notado para o compósito (PL-Alg), mantendo-se fixa a concentração de PEG e alginato, sendo este último adicionado com o intuito de ser um segundo precursor de rede para reticular o hidrogel de PEG-Laponita. Ainda, todos os compósitos apresentaram uma recuperação parcial da viscosidade em função do tempo, após a aplicação de cisalhamento, parâmetro a ser considerado no desenvolvimento de biotintas. Os arcabouços de PL-Alg foram impressos contendo até 10 camadas e colocados em uma solução de CaCl2 para a reticulação das cadeias do alginato. Posteriormente, testes in vitro foram realizados, mostrando que a dissolução da rede do hidrogel compósito foi mais crítica para a amostra com 5% de Laponita. Em conclusão, para trabalhos futuros deverá ser considerada a maneira mais apropriada de reticulação da cadeia de PEG, para melhorar as propriedades mecânicas e a resistência à degradação, viabilizando a utilização do sistema PEG-Laponita-alginato para aplicações em bioimpressão 3D.

Proceedings of the 2nd (ICAIC) International Conference for Academia and Industry Co-operation & 2nd (IMMSEM) International Meeting in Materials Science and Engineering of Maranhão (978-65-5941-476-5) - Síntese De Pós Biocerâmicos Dos Sistemas Cao-Mgo-Sio2 E Sio2-Zro2 Por Sol-Gel E Coprecipitação