Browsing by Subject "Controlled release"

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Open Access
Controlled enzymatic stability and release characteristics of supramolecular chiral peptide amphiphile nanofiber gels
(Elsevier B.V., 2017) Zengin, A.; Cinar, G.; Güler, Mustafa O.
Supramolecular bioarchitectures formed by assembly of achiral or chiral building blocks play important roles in various biochemical processes. Stereochemistry of amino acids is important for structural organization of peptide and protein assemblies and structure-microenvironment interactions. In this study, oppositely charged peptide amphiphile (PA) molecules with L-, D- and mixture of L- and D-amino acid conformations are coassembled into supramolecular nanofibers and formed self-supporting gels at pH 7.4 in water. The enzymatic stability of the PA nanofiber gels was studied in the presence of proteinase K enzyme, which digest a broad spectrum of proteins and peptides. The structural changes on the chiral PA nanofibers were also analyzed at different time periods in the presence of enzymatic activity. Controlled release of a model cargo molecule through the chiral PA nanofiber gels was monitored. The diffusivity parameters were measured for all gel systems. Release characteristics and the enzymatic stability of the peptide nanofiber gels were modulated depending on organization of the chiral PA molecules within the supramolecular assemblies.
Open Access
Enzymatic degradation of self-assembled peptide nanofiber gels
(2016-02) Zengin, Aygül
The self-assembled peptide nano ber gels have received enormous attention because of their inherent biocompatible, biodegradable and functional properties. They provide a smart platform for a range of applications such as tissue engineering, drug delivery and wound healing. These gels are formed through noncovalent interactions such as hydrogen bonding, hydrophobic interactions and electrostatic interactions among the peptide amphiphile molecules at physiological conditions. In order to understand the stability of these gels in the presence of proteases in natural conditions, we studied degradation behavior of the gels with proteinase K, which is a non-speci c protease cleaving the peptide bonds. Degradation process was studied by measuring weight measurement and TEM imaging. In addition, sustained release of Rhodamine B from these gels was also studied in the presence of proteases. The results clearly demonstrated that presence of D- amino acids in the peptide nano ber network signi cantly improves their stability against enzymatic degradation and change the release pro le of the encapsulated molecules in the gels. These ndings are interesting for biomedical applications of these materials due to their tunable degradation and controlled release behavior.