Size Of Mesoporous Silica Nanoparticles Research Articles

Low-angle X-ray scattering for the determination of the size of mesoporous silica nanoparticles

In the last two decades, Mesoporous Silica Nanoparticles (MSNs) were given a substantial interest due to their unique properties and wide range of applications. The size is a key feature which determines the use of MSNs. Transmission Electron Microscopy (TEM) is a standard technique for MSNs’ size determination. Despite reliable, yet it has some drawbacks, being time consuming, destructive and requires complex sample preparation. Therefore, this work aims at introducing Low-angle X-ray Scattering (LAXS) as a time-saving, non-destructive and inexpensive tool for the determination of the size of MSNs. Different sizes of MSNs are prepared using different concentrations of ammonium hydroxide (catalyst) and their corresponding LAXS profiles are recorded. LAXS profile parameters (peak position and area under peak) are found to exhibit a strong linear dependence on the size of MSNs determined using the standard TEM technique. Moreover, the pore sizes calculated from LAXS profiles show linear dependence on the size of MSNs. For MSNs in the range from 60 to 170 nm, two mathematical linear fitting equations are introduced for the determination of the size of MSNs by direct substitution using LAXS profile parameters. One more equation is introduced for the calculation of the size of MSNs directly from their pore size.

The pore size of mesoporous silica nanoparticles regulates their antigen delivery efficiency.

Subunit vaccines generally proceed through a 4-step in vivo cascade-the DUMP cascade-to generate potent cell-mediated immune responses: (1) drainage to lymph nodes; (2) uptake by dendritic cells (DCs); (3) maturation of DCs; and (4) Presentation of peptide-MHC I complexes to CD8+ T cells. How the physical properties of vaccine carriers such as mesoporous silica nanoparticles (MSNs) influence this cascade is unclear. We fabricated 80-nm MSNs with different pore sizes (7.8 nm, 10.3 nm, and 12.9 nm) and loaded them with ovalbumin antigen. Results demonstrated these MSNs with different pore sizes were equally effective in the first three steps of the DUMP cascade, but those with larger pores showed higher cross-presentation efficiency (step 4). Consistently, large-pore MSNs loaded with B16F10 tumor antigens yielded the strongest antitumor effects. These results demonstrate the promise of our lymph node-targeting large-pore MSNs as vaccine-delivery vehicles for immune activation and cancer vaccination.

Fabrication and characterization of gemcitabine hydrochloride loaded mesoporous silica nanoparticles as theranostics platform for pancreatic cancer

ABSTRACT The aim of present study was to develop mesoporous silica nanoparticles that have a combination of therapeutic and diagnostic functionalities (theranostics), with the ultimate goal ofcreating smart nanocarriers the therapeutic actions of which are controlled by diagnostic information. Folic acid conjugation was carried out to prevent premature release of cargo and to achieve the goal of targeted therapy. The mesoporous silica was made to absorb gemcitabine hydrochloride, a BCS Class III drug, using a wetness impregnation method. Physicochemical characterization of the preparation was carried out using infrared spectroscopy, particle size analysis, transmission electron microscopy, drug uptake study and fluorescence microscopy. The particle size of Mesoporous silica nanoparticles i.e, SBA-15 was found to be 564.5 nm. The average pore diameter was found to be of 49.88 nm, and the surface area was 120.031 m2/g. The drug-loaded SBA-15 exhibited 47.3% drug release within 10 hours in phosphate buffer of pH 7.4.

Mesoporous silica nanoparticles for efficient rivastigmine hydrogen tartrate delivery into SY5Y cells

Rivastigmine hydrogen tartrate (RT) is a molecule with both hydrophilic and hydrophobic properties used for the treatment of the Alzheimer’s disease. In this work, the larger pore size of mesoporous silica nanoparticles (P1-MSN) was synthesized and then, P1-MSN were functionalized by succinic anhydride (S-P1-MSN) and 3-aminopropyltriethoxysilane (APTES) (AP-CO-P1-MSN) using the grafting and co-condensation methods, respectively. A new method was used for the functionalization of P1-MSN by succinic anhydride at room temperature. Nanoparticles were characterized by special instrumental analysis and loaded by RT. Maximum entrapment efficiency and RT loading percentage into P1-MSN, AP-CO-P1-MSN and S-P1-MSN were respectively obtained as 21.26 and 25.5%, 41.5 and 49.8%, and 11.9 and 14.28% for 24 h. In the simulated gastric and body fluids, the release rate of RT-loaded AP-CO-P1-MSN (AP-CO-P1-MSN-RT) was lower than that of other RT-loaded nanoparticles. In oral pathway, the sustained release of RT was observed in AP-CO-P1-MSN-RT. Moreover, no cytotoxicity effect was observed for P1-MSN, but the cells treated by AP-CO-P1-MSN showed a reduction in SY5Y cell viability due to easy entrance of these nanoparticles and their accumulation in different parts of the cell as observed by TEM.

Tuning pore size of mesoporous silica nanoparticles simply by varying reaction parameters

Mesoporous silica nanoparticles (MSN) with tunable pore size have been proved to be excellent potential in molecular-related applications. Herein, in this study, we designed to synthesize MSN with tunable pore size by varying the n-octadecyltrimethoxysilane (C18TMS)/tetraethylorthosilicate (TEOS) molar ratio or the ethanol (EtOH)/H2O volume ratio in a water-ethanol-ammonia system, where C18TMS acted as structure-directing agent, TEOS as silica source, ammonia as catalyst, EtOH and H2O as solvents. The as-obtained MSN were characterized by the scanning electron microscopy (SEM), transmission electron microscopy (TEM) and N2 adsorption-desorption analysis. The results showed that the as-synthesized MSN possessed spherical morphology with diameter ranging from 100 to 200nm, and the pore size of MSN could be easily tailored from 2.4 to 6.5nm simply by varying the C18TMS/TEOS molar ratio from 0.32 to 0.74 and the EtOH/H2O volume ratio from 3.6 to 7.5. Meanwhile, the pore volume also could be adjusted from 0.6 to 1.0cm3/g by this strategy. These results suggested that our strategy could effectively enlarge and adjust the mesopores of the MSN. We supposed our approach may provide a platform of nanotechnology for preparation of porous silica materials with adjustable mesopores which would be great potential in practical applications where different sizes of molecules were involved.

Tailoring Particle Size of Mesoporous Silica Nanosystem To Antagonize Glioblastoma and Overcome Blood-Brain Barrier.

The blood-brain barrier (BBB) is the main bottleneck to prevent some macromolecular substance entering the cerebral circulation, resulting the failure of chemotherapy in the treatment of glioma. Cancer nanotechnology displays potent applications in glioma therapy owing to their penetration across BBB and accumulation into the tumor core. In this study, we have tailored the particle size of mesoporous silica nanoparticles (MSNs) through controlling the hydrolysis rate and polycondensation degree of reactants, and optimized the nanosystem that could effectively penetrate BBB and target the tumor tissue to achieve enhanced antiglioma efficacy. The nanoparticle was conjugated with cRGD peptide to enhance its cancer targeting effect, and then used to load antineoplastic doxorubicin. Therefore, the functionalized nanosystem (DOX@MSNs) selectively recognizes and binds to the U87 cells with higher expression level of ανβ3 integrin, sequentially enhancing the cellular uptake and inhibition to glioma cells, especially the particle size at 40 nm. This particle could rapidly enter cancer cells and was difficult to excrete outside the cells, thus leading to high drug accumulation. Furthermore, DOX@MSNs exhibited much higher selectivity and anticancer activity than free DOX and induced the glioma cells apoptosis through triggering ROS overproduction. Interestingly, DOX@MSNs at about 40 nm exhibited stronger permeability across the BBB, and could disrupt the VM-capability of glioma cells by regulating the expression of E-cadherin, FAK, and MMP-2, thus achieving satisfactory antiglioblastoma efficacy and avoiding the unwanted toxic side effects to normal brain tissue. Taken together, these results suggest that tailoring the particle size of MSNs nanosystem could be an effective strategy to antagonize glioblastoma and overcome BBB.

Impact of Shape and Pore Size of Mesoporous Silica Nanoparticles on Serum Protein Adsorption and RBCs Hemolysis

With the rapid development of nanotechnology, mesoporous silica nanoparticles (MSNs) with numerous forms and structures have been synthesized and extensively applied in biomedicine in the past decades. However, our knowledge about the biocompatibility of the developed MSNs has not matched their development. Therefore, in this work, we have synthesized sphere-shaped MSNs with different pore scales (s-SPs and l-SPs) and rod-shape (RPs-3) MSNs to evaluate the influence of the morphology and pore size on their interaction with serum proteins and red blood cells (RBCs). The adsorption of human albumin (HSA), globulin (HGG), and fibrinogen (HSF) onto different kinds of MSNs has been analyzed by pseudo second-order kinetic model, and the conformational changes of the adsorbed proteins have been studied by FTIR spectroscopy. We find that the conformation of absorbed HSA and HSF, while not HGG, will be affected by the pore size and morphology of the MSNs. The conformational changes of the adsorbed proteins will further affect their saturated adsorption capacity. However, the initial adsorption rate is only determined by the property of MSNs and proteins. Additional hemolysis assay shows that the pore size and morphology of the MSNs will also affect their hemolytic activity in RBCs which will be extremely depressed by the formation of protein corona. These systematic studies will provide an overall understanding in the blood compatibility of MSNs as well as useful guidelines for fabrication of blood-compatible nanomaterials.

Successfully tailoring the pore size of mesoporous silica nanoparticles: Exploitation of delivery systems for poorly water-soluble drugs

A novel approach was applied to fabricate mesoporous silica nanoparticles (MSNs) with different pore size in this study. The pore size of MSNs can be modulated conveniently from 3 nm to 10nm by controlling the etching time of MSNs with the NaBH(4) solution. The as-synthesized MSNs were investigated as carriers for loading and delivery of the model drug paclitaxel (PTX). The characteristics, drug loading capacity, in vitro drug release behavior, anti-tumor activity and the mechanism of cell uptake were systematically studies. The resultant MSNs showed uniform and mono-dispersed sphere with high drug loading capacity (12-21%). The in vitro drug release exhibited that the released rate of PTX from MSNs could be controlled by the pore size and the larger the pore size, the faster the release rate of PTX. The in vitro anti-tumor studies demonstrated that PTX-loaded MSNs produced higher cytotoxicity than free PTX. Besides, the PTX-loaded MSNs with largest pore size showed the highest anti-tumor activity. These results indicated that these MSNs could provide a promising platform for delivering water-insoluble drugs, controlling the release rate of drugs and increasing the anti-tumor activity.