Publicação
Microencapsulation using alginate systems: spray-coagulation versus superhydrophobic surfaces approach
| Resumo: | The use of biopolymers such as alginate has been growing in the last decades due to properties such as biocompatibility, non-toxicity and biodegradability. In this work the microencapsulation of a hydrophobic (curcumin) and a hydrophilic (safranin), used as model compounds with alginate matrices, was studied by comparing two encapsulation methods (spray coagulation and superhydrophobic surfaces) and by testing three calcium sources (calcium chloride, calcium gluconate and calcium lactate) to promote the alginate ionic crosslinking. The microspheres obtained through the spray/coagulation technique were characterized in terms of load, encapsulation efficiency and rehydration capacity. The release profiles of both active principles were evaluated. The results revealed that when calcium chloride is used a higher encapsulation efficiency was obtained (99.25% and 98.50%, respectively for curcumin and safranin), followed by calcium gluconate (98.45% and 97.55 for curcumin and safranin) and finally calcium lactate (97.91% for curcumin and 97.42 for safranin). Regarding the release profile, a lower release was achieved, for both compounds, when calcium chloride was used (5.70% of curcumin in ethanol medium, and 4.15% of safranin in distilled water), followed by the calcium gluconate crosslinked microspheres (8.3% for curcumin and 4.42% for safranin). Calcium lactate crosslinked microspheres give rise to the systems with higher release (12.1% for curcumin and 4.76% for safranin). The microspheres had a spherical conformation and the larger particle size (volume distribution) was obtained with the calcium gluconate-based systems (131.46, 78.85 and 91.46 μm for curcumin, safranin and empty microspheres, respectively). The calcium chloride-base systems give rise to the smallest ones (91.65, 60.10 and 80.31 μm, respectively for curcumin, safranin and empty microspheres). Through Fourier Transform Infrared Spectroscopy the contribution of the calcium source and the active principle on the microspheres spectra was identified, and thermogravimetric analysis evidenced an increasing of the thermal stability due to the alginate crosslinking effect, particularly when calcium chloride was used. Regarding the comparison of the two microencapsulated systems, the superhydrophobic surfaces showed a good performance having in view the encapsulation with alginate systems, since no loss of the active principle to the surface during the process was observed (qualitative analysis). This constitute an advantage particularly for the case of the hydrophilic active principles. |
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| Autores principais: | Cuma, Diana Francisco |
| Assunto: | Microencapsulation Alginate systems |
| Ano: | 2018 |
| País: | Portugal |
| Tipo de documento: | dissertação de mestrado |
| Tipo de acesso: | acesso aberto |
| Instituição associada: | Instituto Politécnico de Bragança |
| Idioma: | inglês |
| Origem: | Biblioteca Digital do IPB |
| Resumo: | The use of biopolymers such as alginate has been growing in the last decades due to properties such as biocompatibility, non-toxicity and biodegradability. In this work the microencapsulation of a hydrophobic (curcumin) and a hydrophilic (safranin), used as model compounds with alginate matrices, was studied by comparing two encapsulation methods (spray coagulation and superhydrophobic surfaces) and by testing three calcium sources (calcium chloride, calcium gluconate and calcium lactate) to promote the alginate ionic crosslinking. The microspheres obtained through the spray/coagulation technique were characterized in terms of load, encapsulation efficiency and rehydration capacity. The release profiles of both active principles were evaluated. The results revealed that when calcium chloride is used a higher encapsulation efficiency was obtained (99.25% and 98.50%, respectively for curcumin and safranin), followed by calcium gluconate (98.45% and 97.55 for curcumin and safranin) and finally calcium lactate (97.91% for curcumin and 97.42 for safranin). Regarding the release profile, a lower release was achieved, for both compounds, when calcium chloride was used (5.70% of curcumin in ethanol medium, and 4.15% of safranin in distilled water), followed by the calcium gluconate crosslinked microspheres (8.3% for curcumin and 4.42% for safranin). Calcium lactate crosslinked microspheres give rise to the systems with higher release (12.1% for curcumin and 4.76% for safranin). The microspheres had a spherical conformation and the larger particle size (volume distribution) was obtained with the calcium gluconate-based systems (131.46, 78.85 and 91.46 μm for curcumin, safranin and empty microspheres, respectively). The calcium chloride-base systems give rise to the smallest ones (91.65, 60.10 and 80.31 μm, respectively for curcumin, safranin and empty microspheres). Through Fourier Transform Infrared Spectroscopy the contribution of the calcium source and the active principle on the microspheres spectra was identified, and thermogravimetric analysis evidenced an increasing of the thermal stability due to the alginate crosslinking effect, particularly when calcium chloride was used. Regarding the comparison of the two microencapsulated systems, the superhydrophobic surfaces showed a good performance having in view the encapsulation with alginate systems, since no loss of the active principle to the surface during the process was observed (qualitative analysis). This constitute an advantage particularly for the case of the hydrophilic active principles. |
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