Exploring the structure of sol-gel-derived hybrids for immobilization of RNA: Influence of RNA content

In this work, RNA oligonucleotides (yeast) were immobilized in silica (SiO₂)/polyethylene glycol (PEG) hybrid particles. Two different particulate hybrids containing 55 and 110 μg RNA per g of SiO₂ precursor were prepared using hydrous sol-gel route at room temperature. The molar PEG:TEOS ratio was kept at 0.65. The structural development in RNA-immobilized hybrids was characterized using X-ray diffraction (XRD), gas adsorption (N₂), scanning electron microscopy (SEM), Fourier-transform infrared (FTIR), and X-ray photoelectron (XPS) spectroscopy techniques. RNA oligonucleotides were immobilized in pores close to surface; however, they were immobilized in interior structure when PEG hybridization was performed. Along with structural differences that occurred by increasing the RNA load, RNA immobilization in the hybrid silica/PEG network could be performed without phase separation. Doubling the RNA content resulted in plate-like particle formation. In the overall, results indicate that oligonucleotides could be effectively shielded in the interior mesopores of the silica/PEG hybrids. They did not leak out of particles into the tris-EDTA buffer up to 48 h. This work indicated that RNA-immobilized silica/PEG matrices are promising candidates for use in stationary biological tools that require maximized level of oligo-loading capacity.