@article {19393,
	title = {Engineered natural polymers films: an alternative delivery platform},
	journal = {Term Stem 2017},
	year = {2017},
	month = {2017-11-15 00:00:00},
	address = {Porto},
	abstract = {<p>A renewed interest in the use of natural compounds derived medicinal plants arises due to their composition and intrinsic bioactive properties. Therefore, the beneficial health effects of aloe vera (AV), and its phytocompounds have been demonstrated in the treatment of many diseases. Acemannan (ACE), the main polysaccharide of AV leaves is recognized for its cytocompatibility, wound healing inducer, antibacterial action and immunomodulator activity. This study intends to design films through the combination of ACE with chitosan (CHT) and alginate (ALG). The strong synergistic effects established between these natural polymers is a consequence of the interaction among these polymers and the formation of mixed junction zones. For that purpose, solutions of ACE, ALG and CHT were prepared using water and acetic acid 1\%(v/v), respectively. The blended solutions, defined as CHT/ACE, ALG/ACE or CHT/ALG, were prepared using previously defined volumes of the original solutions. Those were casted in the moulds and left to dry at 37{\textordmasculine}C for 24h. CHT/ALG system act as a comparable model. The films were characterized using different techniques to define their physical features and chemical composition as well as the interaction established between the matrices into the blended formulations. Rheological studies revealed that the studied solutions have a non-newtonian behavior. The storage modulus (G{\textquoteright}) and the loss modulus (G{\textquoteright}{\textquoteright}) increased with frequency, which is attributed to the interactions between the polymeric chains. \&nbsp;At lower frequencies, G{\textquoteright} and G{\textquoteright}{\textquoteright} were almost independent of the frequency, indicating the creation of a network structure formed by the interactions between the polymeric chains. This feature is also confirmed by viscosity increase as a result of polymers combination. Moreover, the ACE release was evaluated at different pHs for pre-determined times. As expected, only when CHT was present, the ACE release and swelling of the films were influenced by the pH of the medium, being favored at most acidic pHs. The XPS spectra of the blended samples, when compared with films of the isolated polymers, presented differences in the N1s, besides the two peaks atributed to amine and amide groups, a third peak representative of the protonated amine appeared, related to the arrangement of the polymers. The findings, obtained until now, suggested, that the ACE-based films could be good candidates as bioactive delivery platforms.</p>},
	keywords = {Blended membranes, natural origin polymers},
	author = {Rodrigues, L.C. and Silva, S. S. and Reis, R. L.}
}
