TY - JOUR

T1 - Assessing the efficiency of SBA-15 as a nanocarrier for diphtheria anatoxin

AU - Rasmussen, Martin Kjærulf

AU - Bordallo, Heloisa N.

AU - Bordenalli, Marcela Aparecida

AU - Akamatsu, Milena Apetito

AU - Trezena, Aryene Goes

AU - Tino-De-Franco, Milene

AU - Sant'Anna, Osvaldo A.

AU - Martins, Tereza da Silva

AU - de Souza Lopes, Jose Luiz

AU - de Abreu Fantini, Marcia Carvalho

AU - Pinto Oliveira, Cristiano Luis

PY - 2021/1

Y1 - 2021/1

N2 - SBA-15 ordered mesoporous silica can be considered a promising inorganic nanocarrier with emerging potential as an oral vaccine adjuvant. In this study, we investigated its application in the encapsulation of the diphtheria anatoxin (dANA). We observed a considerable preservation of dANA secondary and tertiary structures, even after the drying process by means of Circular Dichroism (CD) and fluorescence spectroscopies. Antigen loading was assessed at a number of different ratios of adjuvant-to-antigen using a combination of nitrogen adsorption porosimetry and Small Angle X-ray Scattering (SAXS). Our data showed that the mass ratio of 1:10 (dANA:SBA-15) is recommended for total encapsulation of dANA in the mesopores, considering that at this relative mass concentration antigen clustering was avoided, which is deleterious effect for immunization purposes. dANA release in mimetic intestine fluid, at a pH equal to 6.8, was followed by in-situ SAXS measurements and shown to be slow, being more pronounced after 6 h and continuous up to 35 h. Finally, the immunogenic complex was tested in isogenic Balb C mice by oral and subcutaneous immunization routes, including a comparison with the only permitted adjuvant for human use, aluminum hydroxide. A higher antibody titer was obtained by subcutaneous and oral administration routes using SBA-15 as the vehicle of dANA, compared with the conventional aluminum hydroxide, demonstrating the viability to use this ordered mesoporous silica in the formulation of oral vaccines, as already proved for the Virus Like Particles (VLP) Hepatitis B (HBsAg) case.

AB - SBA-15 ordered mesoporous silica can be considered a promising inorganic nanocarrier with emerging potential as an oral vaccine adjuvant. In this study, we investigated its application in the encapsulation of the diphtheria anatoxin (dANA). We observed a considerable preservation of dANA secondary and tertiary structures, even after the drying process by means of Circular Dichroism (CD) and fluorescence spectroscopies. Antigen loading was assessed at a number of different ratios of adjuvant-to-antigen using a combination of nitrogen adsorption porosimetry and Small Angle X-ray Scattering (SAXS). Our data showed that the mass ratio of 1:10 (dANA:SBA-15) is recommended for total encapsulation of dANA in the mesopores, considering that at this relative mass concentration antigen clustering was avoided, which is deleterious effect for immunization purposes. dANA release in mimetic intestine fluid, at a pH equal to 6.8, was followed by in-situ SAXS measurements and shown to be slow, being more pronounced after 6 h and continuous up to 35 h. Finally, the immunogenic complex was tested in isogenic Balb C mice by oral and subcutaneous immunization routes, including a comparison with the only permitted adjuvant for human use, aluminum hydroxide. A higher antibody titer was obtained by subcutaneous and oral administration routes using SBA-15 as the vehicle of dANA, compared with the conventional aluminum hydroxide, demonstrating the viability to use this ordered mesoporous silica in the formulation of oral vaccines, as already proved for the Virus Like Particles (VLP) Hepatitis B (HBsAg) case.

KW - Diphtheria anatoxin

KW - Ordered mesoporous silica

KW - Oral vaccine

KW - PROTEIN SECONDARY STRUCTURE

KW - MESOPOROUS SILICA

KW - BIOLOGICAL MACROMOLECULES

KW - SOLUTION SCATTERING

KW - IMMUNE-RESPONSE

KW - ORAL DELIVERY

KW - VACCINE

KW - ANTIGEN

KW - ADJUVANT

KW - MUCOSAL

U2 - 10.1016/j.micromeso.2020.110763

DO - 10.1016/j.micromeso.2020.110763

M3 - Journal article

VL - 312

JO - Zeolites

JF - Zeolites

SN - 1387-1811

M1 - 110763

ER -