How Advancing are Mesoporous Silica Nanoparticles? A Comprehensive Review of the Literature.

The application of mesoporous silica nanoparticles (MSNs) is ubiquitous in various sciences. MSNs possess unique features, including the diversity in manufacturing by different synthesis methods and from different sources, structure controllability, pore design capabilities, pore size tunability, nanoparticle size distribution adjustment, and the ability to create diverse functional groups on their surface. These characteristics have led to various types of MSNs as a unique system for drug delivery. In this review, first, the synthesis of MSNs by different methods via using different sources were studied. Then, the parameters affecting their physicochemical properties and functionalization have been discussed. Finally, the last decade's novel strategies, including surface functionalization, drug delivery, and cancer treatment, based on the MSNs in drug delivery and cancer therapy have been addressed.

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.

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 mechanism of cell death, was evaluated by morphological study of the MCF-7 cells. Within acceptable toxicity limits and apoptosis induction, the Dox-loaded nanocarriers, especially discrete mode synthesized nanocarriers, exhibited high-efficiency anticancer effect on the MCF-7 cell line.

CO2 reforming of CH4 over CeO2-doped Ni/Al2O3 nanocatalyst treated by non-thermal plasma.

Ni/Al2O3 and Ni/Al2O3-CeO2 nanocatalysts have been prepared with impregnation method, treated with non-thermal plasma, characterized and tested for dry reforming of methane. For catalyst characterization, the following techniques have been used: XRD, FESEM, TEM, EDX dot mapping, BET, FTIR, TG-DTG, and XPS techniques. According to XRD and XPS, Ni in all catalysts exists as NiO and NiAl2O4 that existence of NiAl2O4 reveals strong interaction between active phase and support. Catalyst particles had smaller average particle size in plasma treated Ni/Al2O3-CeO2 nanocatalyst with less agglomeration. Homogenous dispersion of active phase, narrower particle size distribution, and uniform morphology has been observed in ceria containing plasma treated catalyst. The plasma treated Ni/Al2O3-CeO2 nanocatalyst showed bigger NiAl2O4/NiO ratio in XPS analysis that is indicative of stronger interaction between Ni and Al2O3 in the presence of CeO2. The dry reforming of methane was carried out at 550-850 degrees C using a mixture of CH4:CO2 (0.5:2). Improved morphology of the plasma treated Ni/Al2O3-CeO2 nanocatalyst, resulted from both CeO2 and plasma treatment, caused higher ability of catalyst in H2 and CO production. Product yield decreased at higher GHSVs, due to the fact that mass transport limitations will be more severe at low residence time, but this reduction would be less noticeable in the plasma treated Ni/Al2O3-CeO2 nanocatalyst. In addition, the plasma treated Ni/Al2O3-CeO2 nanocatalyst can keep the reactivity without deactivation for either CH4 or CO2 conversion better than other investigated catalysts.