Navegando por Autor "Souza, Tiago Marcolino de"

Agora exibindo 1 - 5 de 5

Comparing the nanoscale topography and interface properties of chitosan films containing free and nano-encapsulated copaiba essential oil : an atomic force microscopy (AFM) and fractal geometry study.
(2023) Pinto, Erveton Pinheiro; Menezes, Rodrigo Prioli; Pires, Marcelo Amanajás; Zamora, Robert Ronald Maguiña; Araújo, Raquel Silva; Souza, Tiago Marcolino de
This article compared chitosan films containing copaiba essential oil (CO) and nano-encapsulated CO using nanoscaled topographic characteristics and interface properties. The CO-loaded nanocapsules (CO-NC) were prepared by the polymer nanoprecipitation method, whereas the composite films were produced by the casting method. The films’ surface was evaluated by atomic force microscopy (AFM) and scanning electron microscopy (SEM). Wettability and adhesion were also investigated by measuring the contact angle and AFM. The results suggested that the film’s surface containing CO-NC presented characteristics that favor interface interactions at the nanoscale. Furthermore, these films showed greater interaction with water and superior adhesion force than the control and CO-loaded chitosan films. Thus, considering the surface characteristics and the evaluated properties, CO-NC seems to be a promising alternative for incorporating CO in chitosan films.
Copaiba essential oil loaded-nanocapsules film as a potential candidate for treating skin disorders : preparation, characterization, and antibacterial properties.
(2023) Pinto, Erveton Pinheiro; Menezes, Rodrigo Prioli; Tavares, Walter de Souza; Ferreira, Adriana Maciel; Sousa, Francisco Fábio Oliveira de; Silva, Gabriel Araújo da; Zamora, Robert Ronald Maguiña; Araújo, Raquel Silva; Souza, Tiago Marcolino de
Infections have emerged as a novel target in managing skin and mucosa diseases. Bacterial resistance to anti- microbials and biofilm elimination from surfaces remains a challenge. Because polymeric nanocapsules (NC) can increase antimicrobial activity, this study aimed to produce and characterize NC into chitosan films (CSF). Copaiba essential oil (CO) presents antimicrobial activity and was chosen to load NC. In addition, the antibac- terial activity was evaluated to obtain a new biodegradable polymeric platform system with the potential to treat topical diseases associated with bacterial infections. The CO-NC produced by nanoprecipitation presented par- ticle size lower than 250 nm, negative charge, and encapsulation efficiency higher than 70 %. Direct incorpo- ration of CO into CSF (CO-CSF) by casting method worsened the film’s characteristics. However, incorporating CO-NC into CSF (CO-NC-CSF) avoided these drawbacks demonstrating improved physical, mechanical, morphological, and topographical properties. FTIR results demonstrated possible intermolecular interactions among the polymers and CO. The CO-NC-CSF and CO-CSF presented antibacterial properties against Staphylo- coccus aureus, and Pseudomonas aeruginosa, especially the formulation containing 1 % of CO. These results indicated that CO-NC-CSF is a promising candidate for treating skin disorders.
Lacunarity exponent and Moran index : a complementary methodology to analyze AFM images and its application to chitosan films.
(2021) Pinto, Erveton Pinheiro; Pires, Marcelo Amanajás; Matos, Robert Saraiva; Zamora, Robert Ronald Maguiña; Menezes, Rodrigo Prioli; Araújo, Raquel Silva; Souza, Tiago Marcolino de
In this work, we developed new scripts to calculate the lacunarity exponent and Moran’s index of Atomic Force Microscopy (AFM) images. The lacunarity exponent was estimated by combining the Otsu binarization and gliding-box algorithm, and Moran index was introduced to evaluate the surfaces’ spatial autocorrelation. Developed scripts were first validated using numerical simulation of self-similar fractal and self-affine isotropic surfaces. Then, we successfully synthesized chitosan films with different glycerol con- centrations and used the lacunarity and Moran’s index for a thorough characterization. The validation of the proposed scripts using simulated Sierpinski Carpets and 3D artificial surfaces showed promising potential for analyzing AFM images. Finally, the methodology application to AFM images of chitosan films suggested that lacunarity analysis and Moran index determination could complement thin films’ quality processing control.
Poly-ε-caprolactone nanocapsules loaded with copaiba essential oil reduce inflammation and pain in mice.
(2023) Pinto, Erveton Pinheiro; Costa, Sarah Olivia Alves Mendes da; D’Haese, Cecile; Nysten, Bernard; Machado, Francisco Paiva; Rocha, Leandro Machado; Souza, Tiago Marcolino de; Beloqui, Ana; Machado, Renes Resende; Araújo, Raquel Silva
Diverse drugs have been used for the management of inflammation disorders and pain. However, they present many side effects and stimulate the search for new pharmacotherapeutic alternatives. Plant-derived products such as copaiba essential oil (CO) offer beneficial pharmacological effects. On the other hand, essential oil’s low water solubility and physical instability hinder its in vivo application. Thus, poly-ε-caprolactone (PCL)-based nanocarriers have been used to increase their stability and efficacy. This work aimed to encapsulate CO in PCL nanocapsules and evaluate their effect on inflammation models and pain. The polymeric nanocapsules loading CO (CO-NC) were prepared by nanoprecipitation technique, characterized, and analyzed for their anti- inflammatory effect in vitro and in vivo. The results showed that CO-NC presented a spherical shape, 229.3 ± 1.5 nm diameter, and a negative zeta potential (approximately − 23 mV). CO and CO-NC presented anti- inflammatory and antioxidant effects by LPS-activated macrophages (J774 cells). In addition, CO-NC signifi- cantly reduced TNF-α secretion (3-fold) compared to CO. In vivo, pre-treatment with CO or CO-NC (50, 100, 200 mg/kg, intraperitoneal; i.p) reduced the mechanical allodynia, paw edema, and pro-inflammatory cytokines induced by intraplantar (i.pl) injection of carrageenan in mice. Specifically, CO-NC (200 mg/kg; i.p.) reduced the production of TNF-α similar to the control group. Our results support using polymeric nanocapsules for CO delivery in inflammatory conditions.
Simulação de propriedades magnéticas de filmes de ZnO:Mn e ZnO:Co.
(Programa de Pós-Graduação em Engenharia de Materiais. Rede Temática em Engenharia de Materiais, Pró-Reitoria de Pesquisa e Pós-Graduação, Universidade Federal de Ouro Preto., 2008) Souza, Tiago Marcolino de; Boselli, Marco Aurélio
Neste trabalho investigamos as propriedades magnéticas de filmes de semicondutores magnéticos diluídos dos sistemas ZnO:Mn e ZnO:Co através de simulação Monte Carlo. Nas simulações consideramos a interação de superexchange e a interação RKKY (mediada por elétrons ou buracos eletrônicos). Utilizamos concentrações dos íons Mn2+ e Co2+ iguais a 3%, 5%, 10% e 20% e concentrações de elétrons e buracos eletrônicos iguais a 1 × 1016cm−3, 1 × 1017cm−3, 1 × 1018cm−3, 1 × 1019cm−3 e 1 × 1020cm−3. O cálculo da estrutura eletrônica, das interações RKKY e finalmente a simulação das propriedades magnéticas foram realizados de acordo com o modelo [Boselli et al., Phys. Rev. B 62, 8895 (2000); Phys. Rev. B 68, 85319 (2003)], que se trata da aproximação para uma banda de buracos pesados para o cálculo da estrutura eletrônica spin-polarizada através de um modelo de interação RKKY confinado com polarização de portadores. Para os sistemas ZnO:Mn e ZnO:Co com condução do tipo p observamos um aumento da temperatura de Curie à medida que aumentamos a concentração de dopante e a concentração de buracos eletrônicos. As amostras com concentrações de portadores iguais a 1×1016cm−3 e 1×1017cm−3 apresentaram comportamento paramagnético. Para concentração de portadores igual a 1×1018cm−3 os filmes apresentaram comportamento paramagnético para concentrações de dopante iguais a 3%, 5% e 10% e comportamento parcialmente ferromagnético para concentração de dopante igual a 20%. Os filmes com concentração de buracos igual a 1 × 1019cm−3 apresentaram comportamento parcialmente ferromagnético para concentração de dopante igual a 3% e comportamento ferromagnético para concentrações de dopante iguais a 5%, 10% e 20%. Todas as amostras com concentração de buracos igual a 1×1020cm−3 apresentaram comportamento parcialmente ferromagnético. As temperaturas de Curie obtidas variam de 56K a 430K para o sistema ZnO:Mn e de » 13K a 193K para o sistema ZnO:Co. Os filmes com condução do tipo n para os dois sistemas apresentaram comportamento paramagnético em todos os intervalos de concentração de dopante e portadores de carga estudados.