Sistemas poliméricos multifuncionais baseados em micropartículas contendo nanocarreadores para liberação colônica da camptotecina
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Data
2022-02-18
Autores
Boni, Fernanda Isadora
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Universidade Estadual Paulista (Unesp)
Resumo
A superexpressão de receptores na superfície das células tumorais representa um potencial alvo para a vetorização de fármacos no tratamento do câncer. O desenvolvimento de nanopartículas com superfície modificada é uma importante estratégia tecnológica para promover a interação específica com as células tumorais, objetivando um tratamento mais seletivo. Nesse trabalho, sistemas para a via oral, baseados em nanocápsulas (NCs) microencapsuladas em matrizes de goma gelana (GG) e pectina (P) ou amido resistente (AR) foram desenvolvidos como plataforma para a vetorização cólon-específica da camptotecina (CPT), como potencial estratégia para o tratamento local do câncer colônico. Primeiramente, micropartículas vazias (MPs) de GG:P ou GG:AR foram obtidas pelo método de geleificação ionotrópica utilizando os Ca2+ e/ou Al3+ . As MPs apresentaram diâmetro na faixa de 889 a 1793 µm e elevada circularidade. As MPs obtidas a partir de GG:P reticuladas com Al3+ apresentaram o menor diâmetro médio (889 µm). Entre as compostas por GG:AR, a reticulação com Ca2+ (GACa) resultou na formação de partículas menores (~ 1607 µm). A capacidade de absorção de líquido das MPs foi elevada em pH 1,2 e 6,8, no entanto, as taxas de absorção do meio ácido foram menores, principalmente para a GACa. A porcentagem de erosão das MPs foi maior em pH 1,2 (20 a 26 %) e aparentemente ocorreu a nível superficial. Em pH 6,8, a porcentagem de erosão foi de2,5 a 22,6 %, ocorrendo de forma homogênea ao longo da matriz. A reticulação com Ca2+ da GG:AR promoveu uma redução expressiva da degradação enzimática (pH 1,2 e 6,8), atributo promissor para a proteção do fármaco contra a degradação gástrica. A capacidade mucoadesiva das MPs foi evidenciada em ensaio ex vivo com mucosa intestinal suína. Com base nas propriedades consideradas promissoras, as partículas GACa e GPCa forma selecionadas para a incorporação das NCs. Na segunda etapa do trabalho, NCs foram obtidas pelo método de emulsificação/evaporação do solvente, e revestidas com quitosana (QS), ftalato de hidroxipropilmetilcelulose (HP) e/ou ácido hialurônico (AH), a fim de modular as propriedades de superfície. Para tal, nanoemulsões aniônicas foram obtidas variando-se a concentração de polissorbato 80 e revestidas com QS, promovendo a inversão do potencial zeta das partículas formadas. As NCs com a proporção de 1,8 e 3,6:1 de lecitina:QS, foram posteriormente revestidas com AH e HP. As NCs com múltiplas camadas de revestimento com diâmetro < 250 nm, PDI de ~0,25 e potencial zeta de -15 a -31 mV, foram selecionadas para a incorporação da CPT. A eficiência de incorporação da CPT foi >94% e a adição do fármaco resultou na redução do diâmetro das partículas. O ensaio de permeação ex vivo demonstrou que a nanoencapsulação reduziu a taxa de permeação da CPT através da mucosa intestinal em até 3,5×, e o revestimento com AH e HP reduziu o percentual de permeação em 2× comparado às NCs revestidas apenas com QS. A capacidade mucoadesiva das NCs foi demonstrada em testes com mucina, simulando o pH gástrico e entérico. A nanoencapsulação não reduziu a atividade antiangiogênica da CPT, em ensaio com a CAM. Para as NCs contendo CPT, observou-se a ação antiangiogênica localizada, provavelmente devido à capacidade muco/biodesiva, sendo um efeito vantajoso para ação local e redução de efeitos adversos sistêmicos. Na terceira etapa do trabalho, as NCs foram microencapsuladas nas MPs obtidas previamente obtidas, apresentando rendimento entre 80 e 89%, e partículas com diâmetro entre 756 e 921 µm. A eficiência de incorporação das NCs variou de 16 a 56 %, sendo a composição do revestimento das NCs e da matriz das MPs fatores que influenciaram significativamente esse parâmetro. Estudos de mucoadesão in vitro e ex vivo evidenciaram a elevada capacidade mucoadesiva dos sistemas em segmentos do intestino delgado, cólon suíno e discos de mucina, comportamento que pode favorecer a imobilização do sistema no órgão alvo. O ensaio de digestão in vitro indicou a susceptibilidade da matriz à ação enzimática em ambiente gástrico, favorecendo a liberação da CPT nesse meio. As NCs apresentaram um conjunto de atributos favoráveis, demonstrando ser uma plataforma promissora para o tratamento local do câncer colônico, explorando uma via indireta de inibição da progressão tumoral.
The overexpression of receptors on the surface of tumor cells represents a potential target for drug delivery in the treatment of cancer. The development of surface-modified nanoparticles is an important technological strategy to promote specific interaction with neoplastic cells, aiming at a more selective treatment. In this work, oral systems based on nanocapsules (NCs) microencapsulated in matrices of gellan gum (GG) and pectin (P) or resistant starch (AR) were developed as a platform for colon-specific target of camptothecin (CPT), as a potential strategy for the local treatment of colon cancer. First, empty microparticles (MPs) of GG:P or GG:AR were obtained by the ionotropic gelation method using Ca2+ and/or Al3+. The MPs presented diameter in the range of 889 to 1793 µm and high circularity. The MPs obtained from GG:P crosslinked with Al3+ had the smallest mean diameter (889 µm). Among those, the composed of GG:AR, crosslinking with Ca2+ (GACa) resulted in the formation of smaller particles (~ 1607 µm). The liquid absorption capacity of MPs was high at pH 1.2 and 6.8, however, the absorption rates of acid medium were lower, mainly for GACa. The percentage of MPs erosion was higher at pH 1.2 (20 to 26%) and apparently occurred at the surface level. At pH 6.8, the percentage of erosion ranged from 2.5 to 22.6%, occurring homogeneously along the matrix. Crosslinking with Ca2+ of GG:AR blend promoted an expressive reduction of enzymatic degradation (pH 1.2 and 6.8), a promising attribute for the protection of the drug against gastric degradation. The mucoadhesive capacity of MPs was evidenced in an ex vivo assay with porcine intestinal mucosa. Based on the properties considered promising, GACa and GPCa particles were selected for the incorporation of NCs. In the second stage of the work, NCs were obtained by the emulsification/solvent evaporation method, and coated with chitosan (QS), hypromellosee phthalate (HP) and/or hyaluronic acid (HA), in order to modulate the surface properties. For this, anionic nanoemulsions were obtained by varying the concentration of polysorbate 80 and, coated with QS, promoting the inversion of the zeta potential of the particles. The NCs with the ratio of 1.8 and 3.6:1 of lecithin:QS, were later coated with HA and HP. NCs with multiple coating layers with diameter < 250 nm, PDI of ~0.25 and zeta potential of -15 to -31 mV, were selected for CPT incorporation. The incorporation efficiency was >94% and the drug addition resulted in particle diameter reduction. The ex vivo permeation assay showed that nanoencapsulation reduced the permeation rate of CPT through the intestinal mucosa by up to 3.5×, and coating with HA and HP reduced the permeation percentage by 2× compared to NCs coated with QS alone. The mucoadhesive capacity of NCs was demonstrated in mucin tests, simulating gastric and enteric pH. Nanoencapsulation did not reduce the antiangiogenic activity of CPT in an assay with CAM. For NCs containing CPT, localized antiangiogenic action was observed, probably due to the mucus/biodesive capacity, which is an advantageous effect for local action and reduction of systemic adverse effects. In the third stage of the work, the NCs were microencapsulated in the previously obtained MPs, presenting a yield between 80 and 89%, and particles with a diameter between 756 and 921 µm. The NCs incorporation efficiency ranged from 16 to 56%, and the composition of the NC coating and the MPs matrix were factors that significantly influenced this parameter. In vitro and ex vivo mucoadhesion studies showed the high mucoadhesive capacity of the systems in segments of porcine small intestine, colon and mucin discs, a behavior that may favor the immobilization of the system in the target organ. The in vitro digestion assay indicated the susceptibility of the matrix to enzymatic action in the gastric environment, favoring the release of CPT in this medium. NCs showed a set of favorable attributes, proving to be a promising platform for the local treatment of colonic cancer, exploring an indirect pathway of tumor progression inhibition.
The overexpression of receptors on the surface of tumor cells represents a potential target for drug delivery in the treatment of cancer. The development of surface-modified nanoparticles is an important technological strategy to promote specific interaction with neoplastic cells, aiming at a more selective treatment. In this work, oral systems based on nanocapsules (NCs) microencapsulated in matrices of gellan gum (GG) and pectin (P) or resistant starch (AR) were developed as a platform for colon-specific target of camptothecin (CPT), as a potential strategy for the local treatment of colon cancer. First, empty microparticles (MPs) of GG:P or GG:AR were obtained by the ionotropic gelation method using Ca2+ and/or Al3+. The MPs presented diameter in the range of 889 to 1793 µm and high circularity. The MPs obtained from GG:P crosslinked with Al3+ had the smallest mean diameter (889 µm). Among those, the composed of GG:AR, crosslinking with Ca2+ (GACa) resulted in the formation of smaller particles (~ 1607 µm). The liquid absorption capacity of MPs was high at pH 1.2 and 6.8, however, the absorption rates of acid medium were lower, mainly for GACa. The percentage of MPs erosion was higher at pH 1.2 (20 to 26%) and apparently occurred at the surface level. At pH 6.8, the percentage of erosion ranged from 2.5 to 22.6%, occurring homogeneously along the matrix. Crosslinking with Ca2+ of GG:AR blend promoted an expressive reduction of enzymatic degradation (pH 1.2 and 6.8), a promising attribute for the protection of the drug against gastric degradation. The mucoadhesive capacity of MPs was evidenced in an ex vivo assay with porcine intestinal mucosa. Based on the properties considered promising, GACa and GPCa particles were selected for the incorporation of NCs. In the second stage of the work, NCs were obtained by the emulsification/solvent evaporation method, and coated with chitosan (QS), hypromellosee phthalate (HP) and/or hyaluronic acid (HA), in order to modulate the surface properties. For this, anionic nanoemulsions were obtained by varying the concentration of polysorbate 80 and, coated with QS, promoting the inversion of the zeta potential of the particles. The NCs with the ratio of 1.8 and 3.6:1 of lecithin:QS, were later coated with HA and HP. NCs with multiple coating layers with diameter < 250 nm, PDI of ~0.25 and zeta potential of -15 to -31 mV, were selected for CPT incorporation. The incorporation efficiency was >94% and the drug addition resulted in particle diameter reduction. The ex vivo permeation assay showed that nanoencapsulation reduced the permeation rate of CPT through the intestinal mucosa by up to 3.5×, and coating with HA and HP reduced the permeation percentage by 2× compared to NCs coated with QS alone. The mucoadhesive capacity of NCs was demonstrated in mucin tests, simulating gastric and enteric pH. Nanoencapsulation did not reduce the antiangiogenic activity of CPT in an assay with CAM. For NCs containing CPT, localized antiangiogenic action was observed, probably due to the mucus/biodesive capacity, which is an advantageous effect for local action and reduction of systemic adverse effects. In the third stage of the work, the NCs were microencapsulated in the previously obtained MPs, presenting a yield between 80 and 89%, and particles with a diameter between 756 and 921 µm. The NCs incorporation efficiency ranged from 16 to 56%, and the composition of the NC coating and the MPs matrix were factors that significantly influenced this parameter. In vitro and ex vivo mucoadhesion studies showed the high mucoadhesive capacity of the systems in segments of porcine small intestine, colon and mucin discs, a behavior that may favor the immobilization of the system in the target organ. The in vitro digestion assay indicated the susceptibility of the matrix to enzymatic action in the gastric environment, favoring the release of CPT in this medium. NCs showed a set of favorable attributes, proving to be a promising platform for the local treatment of colonic cancer, exploring an indirect pathway of tumor progression inhibition.
Descrição
Palavras-chave
quitosana, goma gelana, ácido hialurônico, nanocápsulas, angiogênese, mucoadesão