Characterization of insulin-loaded alginate nanoparticles produced by ionotropic pre-gelation through DSC and FTIR studies - Analytical Methods & Tools for Lyophilization

Characterization of insulin-loaded alginate nanoparticles produced by ionotropic pre-gelation through DSC and FTIR studies
Received 17 January 2006; revised 10 February 2006; accepted 10 February 2006. Available online 31 March 2006.
Bruno Sarmentoa, , , Domingos Ferreiraa, Francisco Veigab and Ant?nio Ribeiroc
Carbohydrate Polymers
Volume 66, Issue 1 , 5 October 2006,
ScienceDirect
Copyright ? 2006 Elsevier Ltd All rights reserved.
aDepartment of Pharmaceutical Technology, Faculty of Pharmacy University of Porto, Porto, Portugal
bDepartment of Pharmaceutical Technology, Faculty of Pharmacy University of Coimbra, Coimbra, Portugal
cDepartment of Pharmaceutical Technology, Instituto Superior de Ci?ncias da Sa?de-Norte, Gandra, Portugal
Abstract
Insulin-loaded nanoparticles were prepared by ionotropic pre-gelation of alginate with calcium chloride followed by complexation between alginate and chitosan. The influence of the pH and stoichiometry relationship between polyelectrolytes providing individual particles with a nano-scale size was assessed by photon correlation spectroscopy (PCS) and scanning electron microscopy (SEM). Insulin?polyelectrolyte interactions at varying pH and polyelectrolytes stoichiometry were assessed by differential scanning calorimetry (DSC) and Fourier-transform infrared (FTIR) studies. Individual and smaller sizing nanoparticles, around 800 nm, were obtained at pH 4.7 with an alginate:chitosan mass ratio of 6:1. Thermograms of insulin-loaded nanoparticles originated shifts on same unloaded nanoparticle peaks and suggested polyelectrolytes?protein interactions at pH around 4.5?5.0. FTIR spectra of insulin-loaded nanoparticles showed amide absorption bands characteristic of protein spectra and revealed the formation of new chemical entities.
Keywords: Alginate; Chitosan; DSC; FTIR; Insulin; Nanoparticles

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