Chitosan glutamate nanoparticles for protein delivery: development and effect on prolidase stability

Purpose: To evaluate the feasibility of exploiting ultrasonication coupled with ionotropic gelation
in order to prepare tripolyphosphate (TPP)-chitosan glutamate nanoparticles suitable for the delivery
of the enzyme prolidase.
Methods: All the parameters for the preparation of TPP-chitosan nanoparticles in terms of
components weight ratio, ultrasonication conditions and time-saving nanoparticles recovery
conditions were optimized. The best formulation was loaded with the prolidase. All the nanoparticles
were characterized in terms of morphology, size, polydispersity, zeta-potential, yield of the process
and encapsulation efficiency. The in-vitro activity of the prolidase was assessed by capillary
electrophoresis (CE).
Results and conclusions: A TPP to chitosan weight ratio of 0.2:1 combined with one ultrasonication cycle
(4 min using the probe-type sonifier at 75% power) obtained well-formed nanoparticles of spherical
shape, mean size of 365nm (polydispersity index 0.3) and aþ17.94mV zeta potential. A satisfactory
prolidase encapsulation efficiency (43%) was obtained with a yield of the preparation process of 55%.
In vitro study of activity of prolidase, as free enzyme or released from chitosan nanoparticles,
highlighted the ability of chitosan to stabilize the enzyme during all the steps of the preparation process
and to modulate the enzyme activity up to 48 h.