Bio-based amines from renewable resources through catalytic sustainable processes (BIO2BIA)

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Structural Characterization of Microcapsules from Common Bee Pollen for the Development of Delivery Systems

Publication . Ertosun, Seymanur; Aylanc, Volkan; Peixoto, Andreia F.; Santamaria-Echart, Arantzazu; Russo-Almeida, Paulo; Freire, Cristina; Vilas-Boas, Miguel

Exine, 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.

2024Journal article

Open access

Natural sporopollenin microcarriers: Morphological insights into their functional performance for drug encapsulation and release

Publication . Aylanc, Volkan; Peixoto, Andreia F.; Akyuz, Lalehan; Vale, Nuno; Freire, Cristina; Vilas-Boas, Miguel

Natural 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.

2025Journal article

Open access

Cork waste-based adsorbents for glycerol removal from biodiesel: a sustainable alternative to wet washing

Publication . Garção, Maria Isabella Lima; Milani, Eduardo Candido; Camilo, Gabriel Lamino; Diaz De Tuesta, Jose L.; Gomes, Maria Carolina Sérgi; Ribeiro, António E.; Queiroz, Ana; Brito, Paulo

This work aims to use activated carbon from industrial cork waste as a novel method for glycerol removal from crude biodiesel produced using waste cooking oil, combining two residues to obtain both high-quality biodiesel and highly adsorbent activated carbon. The study first optimizes the biodiesel production conditions, achieving the highest ester yield at 30 degrees C, with a 1:9 oil-to-ethanol molar ratio, 1 wt.% NaOH catalyst, and a reaction time of 1 h. Additionally, activated carbons were prepared and characterized from cork waste, showing significantly higher BET surface areas than the raw material. The most promising cork-based materials were then applied to optimize glycerol removal from crude biodiesel through adsorption. A preliminary study identified milled raw cork and its KOH-activated carbon (SBET = 2057 m2/g) as the most effective. Kinetic and equilibrium studies demonstrated that optimal glycerol removal was achieved after 6 h at 25 degrees C using 2 wt.% of KOH-activated cork-based adsorbent, resulting in 88% glycerol removal and a final glycerol content of 0.017 wt.%. These findings demonstrate that cork waste-derived activated carbon is highly effective for biodiesel purification, successfully meeting the quality specifications required by European Standard EN 14214:2012+A2:2019 and offering an innovative solution for waste valorization and sustainable fuel production.

2025Journal article

Open access

Nutritional and Biochemical Assessment of Edible Fruits From Angola's Native Flora

Publication . Rangel, Josefa; Liberal, Ângela; Pires, Tânia C.S.P.; Finimundy, Tiane C.; Barros, Lillian; Monteiro, Filipa; Romeiras, Maria M.; Fernandes, Ângela

Angola's native flora hides a wealth of underexplored edible fruits with significant nutritional and bioactive potential. This study provides a comprehensive evaluation of the physicochemical and bioactive potential of some less explored edible fruits from this country, namely Annona muricata, A. squamosa, A. senegalensis, A. boehmii, Dacryodes edulis, and Strychnos spinosa. Nutritional profiling revealed carbohydrates as the predominant macronutrient, with A. muricata exhibiting the highest concentration (93.3 g/100 g dw). D. edulis, in turn, stood out for its high fat content (40.5 g/100 g dw), while A. senegalensis contained the highest protein levels (15-6 g/100 g dw). Free sugars analysis highlighted A. squamosa for its elevated fructose and glucose levels, contributing to its pronounced characteristic sweetness, whereas D. edulis exhibited minimal sugar content (1.27 g/100 g dw). Organic acid profiling revealed malic acid as dominant. Saturated fatty acids were predominant across most fruits, with A. boehmii showing the highest levels (71.6%), while A. senegalensis was enriched in monounsaturated fatty acids (45.15%). The phenolic analysis revealed a rich profile in bioactive compounds, with A. muricata and A. squamosa exhibiting significant levels of quercetin-3-O-rutinoside, while A. boehmii, S. spinosa, and D. edulis were characterized by distinct major phenolic compounds, such as cyanidin-3-O-glucoside, isorhamnetin-3-O-glucoside, and corilagin, respectively. Antioxidant activity was strongest in D. edulis and A. senegalensis (EC50 = 0.18 and 0.25 mu g/mL, respectively), while A. squamosa exhibited notable antibacterial activity (MIC = 0.3 mg/mL). This study underscores the nutritional and bioactive potential of Angola's native fruits, highlighting their applications in the food, nutraceutical, and pharmaceutical industries.

2025Journal article

Open access