Can self-assembled hydrogels composed of aromatic amino acid derivatives function as drug delivery carriers?

Abstract

Low molecular weight hydrogelators (LMOHGs) have attracted recent attention due to their diversified applications. In an attempt to artificially imitate their importance in the design of drug delivery carriers, we have synthesized two simple N-terminally protected aromatic amino-acid derivatives that form efficient stable hydrogels at room temperature. The gelation properties of the hydrogels have been thoroughly investigated using various techniques and their strength has been determined by rheological studies. In order to explore the efficacy of the hydrogels as tools for drug delivery, we have developed hydrogel nanoparticles (HNPs) using a surfactant and high-speed homogenization approach. Interestingly, our hydrogel nanoparticles display good entrapment efficiency and release kinetics of the model drug 5-fluoro uracil from the hydrogel matrix. Our experimental results reveal that hydrogel II displays slightly higher efficiency as a drug delivery carrier, which may be due to the presence of an aromatic ring in the backbone in comparison to hydrogel I. This increased strength may be attributed to the increase in π–π interactions when the aromatic residue is present in the backbone. Therefore the nanoparticles generated from hydrogel II may have better hydrogen bonding abilities with drugs in comparison to hydrogel I; thus resulting in a slightly slower release of drug from the hydrogel matrix. This fact may shed some light on the candidature of our hydrogels as future carriers for drug delivery. However, further studies to evaluate the candidature of these novel types of aromatic amino acid hydrogel nanoparticles for nano-medical applications are under investigation.