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(Reference retrieved automatically from Web of Science through information on FAPESP grant and its corresponding number as mentioned in the publication by the authors.)

Diphtheria toxoid conformation in the context of its nanoencapsulation within liposomal particles sandwiched by chitosan

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Author(s):
Rescia, Vanessa C. [1, 2] ; Ramos, Henrique R. [3] ; Takata, Celia S. [4] ; de Araujo, Pedro S. [5] ; da Costa, Maria H. B. [1]
Total Authors: 5
Affiliation:
[1] Ctr Biotecnol, Lab Microesferas & Lipossomas, BR-05503900 Sao Paulo - Brazil
[2] Univ Fed Sao Paulo, Dept Med, Disciplina Clin Med, Sao Paulo - Brazil
[3] Ctr Biotecnol, Lab Biotecnol Mol, BR-05503900 Sao Paulo - Brazil
[4] Div Desenvolvimento Tecnol & Prod, Sao Paulo - Brazil
[5] Univ Sao Paulo, Inst Quim, Dept Bioquim, BR-01498 Sao Paulo - Brazil
Total Affiliations: 5
Document type: Journal article
Source: Journal of Liposome Research; v. 21, n. 2, p. 116-123, JUN 2011.
Web of Science Citations: 1
Abstract

Chitosan (alpha alpha-(1-4)-amino-2-deoxy-beta beta-D-glucan) is a deacetylated form of chitin, a polysaccharide from crustacean shells. Its unique characteristics, such as positive charge, biodegradability, biocompatibility, nontoxicity, and rigid structure, make this macromolecule ideal for an oral vaccine delivery system. We prepared reverse-phase evaporation vesicles (REVs) sandwiched by chitosan (Chi) and polyvinylic alcohol (PVA). However, in this method, there are still some problems to be circumvented related to protein stabilization. During the inverted micelle phase of protein nanoencapsulation, hydrophobic interfaces are expanded, leading to interfacial adsorption, followed by protein unfolding and aggregation. Here, spectroscopic and immunological techniques were used to ascertain the effects of the Hoffmeister series ions on diphtheria toxoid (Dtxd) stability during the inverted micelle phase. A correlation was established between the salts used in aqueous solutions and the changes in Dtxd solubility and conformation. Dtxd alpha alpha-helical content was quite stable, which led us to conclude that encapsulation occurred without protein aggregation or without exposition of hydrophobic residues. Dtxd aggregation was 98% avoided by the kosmotropic, PO<SU2--</SU(4). This ion was used to prepare a stable Dtxd and immunologically recognized REV-Chi-PVA formulation in the presence of 50 mM of PO<SU2--</SU(4). Under these conditions, the Dtxd retained its immunological identity. Therefore, we could obtain the maximum Dtxd solubility and stability after contact with CH(3)CO(2)C(2)H(5) to begin its nanoencapsulation within ideal conditions. This was a technological breakthrough, because a simple solution, such as salt, addition avoided heterologous protein use.</. (AU)