Preparation and in-vitro evaluation of mesoporous biogenic silica nanoparticles obtained from rice and wheat husk as a biocompatible carrier for anti-cancer drug delivery

•Biogenic silica nanoparticles could be extracted from agricultural wastes and converted to the sodium silicate solution as mesoporous silica nanoparticles (MSNs) precursors.•The physicochemical properties and drug delivery potential of bio-silica nanoparticles were improved by converted them to MSNs.•The sodium silicate solution adding method to reaction mixture, can be in continuous or discrete forms which affect the MSNs crystallinity, surface area, pore volume, pore diameter and particle size which affects the drug delivery potential.•All of the samples are biocompatible.•MSNs which synthesis by discrete precursors adding form, have higher accumulative released drug and toxicity on MCF-7 cell line. In this study, mesoporous silica nanocarriers were synthesized from natural sources such as rice and wheat husk for drug delivery application. First, the biogenic silica in cereals husk was extracted by acid leaching and then converted to sodium silicate as a silica precursor. Mesoporous silica nanoparticles were then synthesized by adding sodium silicate to the template mixture by continuous and discrete modes during the sol-gel process. The effects of natural sources type and precursor addition method on nanocarriers‘ morphological and physicochemical properties were investigated by XRD, FT-IR, BET and SEM analysis. Our results showed rice husk-based spherical nanocarriers were more crystalline with slit-shaped pores, while wheat husk-based nanocarriers had been composed of spherical nanoparticles with narrow cylindrical pores. The results also showed that by adding the precursor discretely, their hydrophilicity, particle size and pore size increased compared with the continuous mode, probably due to the high initial concentration of the precursor in the reaction mixture. Doxorubicin (Dox), as a model anticancer drug was loaded into the nanocarriers, and the drug release behavior was studied at two different pH values (7.4 and 5.4). In general, the accumulated released drug at pH 5.4 was approximately twice as much as pH 7.4 due to the higher solubility of doxorubicin at acidic environment. Also, the accumulated released drug at pH 5.4 for nanocarriers which had been synthesized by discrete mode, was higher than continuous mode, due to the larger pore diameter of them. The biocompatibility and cytotoxicity of nanocarriers and Dox-loaded nanocarriers were also investigated on the HFF-2 and MCF-7 cell lines, respectively. Moreover, apoptosis, as the mechanis