SBA-15 WITH EXPANDED PORE FOR PROTEIN IMMOBILIZATION

Ordered mesoporous silicas (OMS), such as SBA-15, have been studied as protein and medicine carriers for therapeutic applications, including vaccines. SBA-15 features needle-shaped particles with a mesoporous average diameter of approximately 10 nm. Its composition and two-dimensional hexagonal symmetry (resembling a honeycomb) and tunable surface functionalization are important features that contribute to the development of controlled release systems and improve the biocompatibility of the particles. In this work, the synthesis conditions were adjusted to expand the average mesopore diameter, enabling the encapsulation of larger protein structures or the co-loading of different proteins. The material’s structure was characterized using small-angle X-ray scattering (SAXS), nitrogen adsorption isotherms (NAI), and scanning and transmission electron microscopy (SEM and TEM). The results showed mesopores expanded to three times the diameter of conventional ones, organized into two distinct phases within the material: regions that maintain hexagonal order, and predominant regions with a significant loss of order, attributed to changes in pore arrangement and accessibility. The influence of this heterogeneous structural profile will be explored in the context of controlled protein release under physiological conditions, where the presence of both ordered and disordered pore regions may offer distinct diffusion pathways. Nevertheless, the observed increases in average pore diameter (from 10 to about 30 nm) and total pore volume (from 1.1 to 1.9 cm³/g) are promising indicators, as larger mesopores can accommodate bulky proteins, thereby mitigating conformational stress that could lead to significant structural changes in the adsorbed proteins.

This work was supported by grants #158984/2022-6 from CNPq-Brazil and #2017/17844-8 and #2022/01951-8 from São Paulo Research Foundation (FAPESP)-Brazil.