Electrostatic Interaction on Loading of Therapeutic
Peptide GLP‑1 into Porous Silicon Nanoparticles
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Abstract
Porous silicon (PSi) nanoparticles’
tunable properties are
facilitating their use at highly challenging medical tasks such as
peptide delivery. Because of many different mechanisms that are affecting
the interaction between the peptide and the particle, the drug incorporation
into the mesoporous delivery system is not straightforward. We have
studied the adsorption and loading of incretin hormone glucagon like
peptide 1 (GLP-1) on PSi nanoparticles. The results show that the
highest loading degree can be achieved in pH values near the isoelectric
point of peptide, and the phenomenon is independent of the surface’s
zeta potential. In order to study the interaction between the peptide
and the nanoparticle, we studied the adsorption with lower concentrations
and noticed that also non-Coulombic forces have a big role in adsorption
of GLP-1. Adsorption is effective and pH-independent especially on
low peptide concentrations and onto more hydrophobic nanoparticles.
Reversibility of adsorption was studied as a function of buffer pH.
When the loading is compared to the total mass of the formulation,
the loading degree is 29%, and during desorption experiments 25% is
released in 4 h and can be considered as a reversible loading degree.
Thus, the peptides adsorbed first seem to create irreversibly adsorbed
layer that facilitates reversible adsorption of following peptides