Sandra Rivero; Maria A. Garcia; Adriana Pinotti
Abstract
The influence of natural antioxidants incorporated to biodegradable materials has become a focus of attention in the current food packaging research and development. Chitosan is a functional natural polymer extensively used for tailoring systems or matrices for a different active compound delivery. This ...
Read More
The influence of natural antioxidants incorporated to biodegradable materials has become a focus of attention in the current food packaging research and development. Chitosan is a functional natural polymer extensively used for tailoring systems or matrices for a different active compound delivery. This work was focused on studying the changes undergone by the chitosan matrix because of the addition of ferulic acid as an antioxidant. Thus, both microstructure and physical properties such as solubility, thermal stability, mechanical and barrier properties were monitored. The addition of ferulic acid caused a decrease in both the moisture content and water vapor permeability, an increase in resistance and a change at the structural level evidenced by TEM. Through FTIR spectra and their relationship with chitosan-based film properties, it was demonstrated that ferulic acid was effectively incorporated in the polymer matrix. The amount of the bioactive compound released from the chitosan matrix to a liquid medium was determined. The delivery profile suggested that the release of the antioxidant agent was controlled by two parallel mechanisms, one Fickian-type and the other associated to the high swelling of the matrix. The antioxidant and UV-barrier properties induced by the addition of ferulic acid turned the chitosan films into a potentially active material to be applied on high-fat foods.
Songjun Lia; Ashutosh Tiwari; Yi Gec; Dan Fei
Abstract
A new type of insulin delivery system capable of better self-regulating the release of insulin was reported in this study. This insulin delivery system was made of a low crosslinked insulin-imprinted hydrogel that exhibited pH-dependent interpolymer interactions between poly(methacrylic acid) (PMAA) ...
Read More
A new type of insulin delivery system capable of better self-regulating the release of insulin was reported in this study. This insulin delivery system was made of a low crosslinked insulin-imprinted hydrogel that exhibited pH-dependent interpolymer interactions between poly(methacrylic acid) (PMAA) and poly(ethylene glycol) (PEG). At acidic conditions (such as pH 3.5), this delivery system resembled a highly crosslinked imprinted hydrogel and demonstrated a relatively slow release due to the formation of the PMAA-PEG complexes, which significantly increased physical crosslinking within the hydrogel interior and largely fixed the imprinted networks. On the contrary, at neutral or basic conditions (such as pH 7.4), this delivery system was comparable to a non-imprinted hydrogel and caused a rapid release resulting from the dissociation of the PMAA-PEG complexes. Unlike previously reported non-imprinted hydrogels and highly crosslinked imprinted polymers, which lack either molecular recognition ability or switchable imprinted networks, this unique insulin delivery system was composed of tunable and low crosslinked imprinted networks, which thereby enabled better self-regulation of insulin delivery.
