Percorrer por autor "Peixoto, Andreia F."
A mostrar 1 - 4 de 4
Resultados por página
Opções de ordenação
- Development of natural sporopollenin microcapsules: from bee pollen to versatile biomaterialsPublication . Aylanc, Volkan; Ertosun, Seymanur; Peixoto, Andreia F.; Santamaria-Echart, Arantzazu; Russo-Almeida, Paulo; Vale, Nuno; Freire, Cristina; Vilas-Boas, MiguelThe outer layer of the pollen grain, which plays a crucial role in the continuity of terrestrial plant life, has received significant attention due to its robustness, chemical inertness, and biocompatible structure made of sporopollenin. Herein, we present a straightforward method for producing high-purity (up to 97%) polymeric sporopollenin biocapsules (S-BioCaps) from bee pollen, exploring new plant sources for S-BioCaps, and diversifying the available morphologies to broaden the applications of pollen-based microcapsules. Following a purification process involving defatting, acidolysis, and several washing steps, we removed the inner components of the pollen grains and reduced the protein content to 2%. Confocal laser scanning and scanning electron microscopy images showed that the hollow and 3D S-BioCaps microstructure were preserved, while laser diffraction particle size analysis validated their monodisperse distribution across each pollen type within the size range of 15 to 24 μm. S-BioCaps tended to exhibit hydrophobic behavior when assessed through water dispersion and water marble analysis. Moreover, we sought to figure out the chemical changes occurring in specimens through Fourier-transform infrared analysis, and findings were consistent with simultaneous thermal analysis, where the thermal decomposition of sporopollenin biopolymer reached up to 457 °C. Overall, this work demonstrates a straightforward approach for utilizing pollen grains from Echium sp., Jasione sp., Papaver sp., Amaranthaceae, and Helianthemum sp., collected with the assistance of honeybees, to produce stable S-BioCaps with diverse morphologies, thereby broadening their potential applications as drug delivery microcarriers.
- Natural sporopollenin microcarriers: Morphological insights into their functional performance for drug encapsulation and releasePublication . Aylanc, Volkan; Peixoto, Andreia F.; Akyuz, Lalehan; Vale, Nuno; Freire, Cristina; Vilas-Boas, MiguelNatural sporopollenin microcapsules (SMCs) derived from pollen offer versatility and efficiency for different applications, from environmental remediation to food and therapeutics delivery. A critical gap remains in understanding the relationship between SMCs morphologies and their effectiveness in drug loading and delivery. Herein, we encapsulated 5-Fluorouracil (5-FU), a model anticancer drug, into SMCs derived from seven bee monofloral pollens, each exhibiting distinct morphological features, and examined how their loading and release performance correlated with their morphology. Microscopic and particle size analyses revealed that the chemically purified SMCs were hollow, with sizes ranging from 11.0 to 35.6 μm, without significant size changes after drug loading. Encapsulation efficiency achieved through vacuum-assisted loading (18–28 %) generally surpassed that of passive and compression loading techniques. Moreover, there was a trend of increasing encapsulation efficiency with larger SMC sizes, albeit with some exceptions. In a sequential release environment simulating the in vitro gastrointestinal tract and colonic fermentation, smaller SMCs exhibited a faster release profile, whereas larger ones demonstrated a slower sustained release. The quantity and shape of apertures on SMCs walls significantly impacted their drug-loading capacity and release characteristics. Additionally, natural SMCs remained structurally intact even in the presence of digestive enzymes, varying pH levels, and colonic bacteria, indicating minimal degradation under these conditions. Overall, the findings highlight the significant influence of SMCs morphologies on their functional performance and provide a list of SMCs-based microstructures to guide drug release applications.
- Sporopollenin-based bio-microcapsules as green carriers for controlled delivery of pharmaceutical drugsPublication . Aylanc, Volkan; Peixoto, Andreia F.; Vale, Nuno; Freire, Cristina; Vilas-Boas, MiguelThe production and design of innovative in-body microcarrier platforms for the controlled delivery of bioactive substances to predefined sites continue to hold substantial promise for biotechnology and medicine by increasing their therapeutic benefits. In this scope, plant pollen-based biocapsules, sporopollenin structures, have emerged as an alternative to synthetic ones due to their low-cost, highly uniform size distribution, resistance to physical and chemical conditions, and renewable green sources. Sporopollenin-based microcarriers, acting as a cargo and protective system, can be engineered to tune the biodistribution and therapeutic efficacy of encapsulated pharmaceuticals. Despite these benefits, the attained biocapsules directly from the plant, which have been the subject of research for nearly two decades, face several challenges and limitations, such as their availability without disrupting their layer integrity for all pollen species, dosage tuning, and the exact control of their responses on the immune system. Recent reports of successful oral administration seem, nevertheless, to bring them one step closer to clinical applications. Herein, we discuss the challenges, possible solutions for broadening natural resources and access to pollen, their further development towards the improvement of controlled release and prolonging the residence time in the intestinal lumen, and promising applications in the in vivo models and clinical trials, focusing on progress in biocapsule technology and the main events occurring along the way.
- Structural Characterization of Microcapsules from Common Bee Pollen for the Development of Delivery SystemsPublication . Ertosun, Seymanur; Aylanc, Volkan; Peixoto, Andreia F.; Santamaria-Echart, Arantzazu; Russo-Almeida, Paulo; Freire, Cristina; Vilas-Boas, MiguelExine, in the form of a natural microcapsule, refers to the outermost layer of the pollen grains and is composed of a complex mixture of sporopollenin, a highly resistant polymer, which makes it durable and able to withstand harsh conditions. Distinctive features of sporopollenin have attracted interest in the encapsulation of bioactive substances. Herein, we describe the pathway to producing sporopollenin microcapsules (SMCs) by exploiting bees and trapping common bee pollen pellets, offering a simple approach to acquiring substantial amounts of pollen grains for industrial application. Palynological results showed that separating bee pollen pellets by colour could lead to almost pure products ranging from 90 to 96%, depending on the pollen species. Subsequently, a single extraction technique removed around 82– 86% of the proteinaceous content, which could cause potential allergic reactions in humans. Detailed morphological analysis by scanning electron microscope (SEM), confocal laser scanning microscopy (CLSM), atomic force microscopy (AFM), and laser diffraction particle size (LDPS) analysis proved that the purified SMCs retained their 3D micro-structures, besides being hollow and uniform micron-scale size. Fourier-transform infrared spectroscopy (FTIR) findings point out that the sporopollenin biopolymer structure of the pollen grain comprises distinct aliphatic and aromatic domains, and the purification of the SMCs resulted in the loss of nitrogen-related peaks. The hydrophobic/hydrophilic properties of the SMCs, evaluated by contact angle measurements, showed variability between pollen, depending on the specificities of their chemical structure. Simultaneous thermal analysis (STA) confirmed SMCs thermal stability up to 451 °C. Altogether, we showed that green microcapsules with various morphological properties could be produced by simply processing Castanea spp., Cistus spp., Erica spp., Olea spp, and Rubus spp, all common bee pollen pellets available in large quantities in the northeast of Portugal, but also many other countries. These microcarriers promise applicability to various fields, from pharmaceuticals to the food industry.