In vitro release of L-phenylalanine from ordered mesoporous materials

The applicability of different types of mesoporous materials as pharmaceutical carriers for L-phenylalanine was evaluated. Silicas, such as SBA-15, SBA-16 and KIT-6 were synthesised by hydrothermal method with tetraethyl orthosilicate as the silica source and triblock copolymer P123 as a template. XRD and TEM studies confirmed an ordered hexagonal structure of SBA-15 and a cubic structure of SBA-16 and KIT-6. The materials are characterised by well-developed specific surface areas and large pore volumes. Adsorption of L-phenylalanine over various mesoporous silicas was studied from solution of different pH (5.6-9.4). The greatest sorption capacity was observed at pH 5.6, which is close to the isoelectric point of L-phenylalanine (pI = 5.48). The amount of L-phenylalanine adsorbed on the mesoporous materials decreases at pH 5.6 in the following sequence: KIT-6 > SBA-15 > SBA-16 that was strongly related to the average pore diameter of the samples. The structural and textural features of the silicas seem to be responsible for the different L-phenylalanine release rate. Additionally, it was found that L-Phe release rate exhibited the pH sensitivity. These phenomena allow control of the experiment according to the needs. (C) 2013 Elsevier Inc. All rights reserved.