Tuning the size and concentration of functional molecules coated onto mesoporous silica nanoparticles for efficient therapeutic protein delivery

Abstract

In this work, the importance of the size and concentration of binding sites in mesoporous nanostructures on their performance for protein delivery is reported. Various types of carboxyl-functionalized mesoporous silica (MS) nanoparticles, i.e., SA(x)-MS, PA1(x)-MS and PA2(x)-MS, where x = 5, 10, 15, 20 and 30 mg, were synthesized by using succinic anhydride (SA) and polyacrylic acid with two molecular weights (i.e., 1800 (PA1) and 100,000 (PA2)), respectively. The particles were thoroughly characterized by TGA, FTIR, STEM and zeta potential measurement techniques and then, their biomedical performance was investigated by using a model therapeutic protein, lysozyme. The carboxyl functional molecules concentration (CCOOH) on the particles was increased as a function of the functional molecules type and quantity in the synthesis reaction environment. The maximum CCOOH values were recorded for SA(10)-MS, PA1(15)-MS and PA2(15)-MS, being 827, 1662 and 2137 µmol.g−1, respectively. However, SA(10)-MS, PA1(15)-MS and PA2(10)-MS particles led to the highest lysozyme loading yield values of 63.1%, 90.0% and 71.5% as well as the loading capacities of 631, 900 and 715 mg.g−1, respectively. The controlled lysozyme release rate and some protein conformational changes favored the in vitro antibacterial activity of lysozyme molecules carried by the particles, which followed the order of PA1(15)-MS > PA2(10)-MS > SA(10)-MS.