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The protein corona of mesoporous silica particles is significantly affected by their morphology, pore structure and size. High aspect ratio particles with large 12 nm pores have a high proportion of low molecular weight proteins in comparison to spherical particles with 5 nm pores, which show a homogenous protein coating which is generally constant in protein composition after long incubation times in serum. The pre-formation of a protein corona prior to incubation with microglia cells enhances the cellular uptake of spherical particles but not facetted or high aspect ratio particles.

Mesoporous silica particles (MSPs) enhance the release kinetics of poorly soluble compound probucol (PB) under the influence of a pore-blocking protein corona, prepared with lysozyme protein adsorption. In vivo oral administration experiments show a prolongation in the time to reach maximum systemic concentration and half-life of PB released from the lysozyme-MSP complex in comparison to the MSP alone. Specific hard protein corona complexes can act as functional diffusion barriers for the controlled release of drugs from MSP based formulations.

The protein corona of nanoparticles is becoming a tool to understand the relation between intrinsic physicochemical properties and extrinsic biological behaviour. A diverse set of characterisation techniques such as transmission electron microscopy, mass spectrometry, dynamic light scattering, zeta-potential measurements and surface enhanced Raman spectroscopy are used to determine the composition and physical properties of the soft and hard corona formed around spherical gold nanoparticles. Advanced characterisation via small angle X-ray scattering and cryo-transmission electron microscopy suggests the presence of a thin hard corona of a few nm on 50 nm gold nanoparticles. The protein corona does not cause changes in cell viability, but inhibits the generation of reactive oxygen species in microglia cells. When a pre-incubated layer of fibrinogen, a protein with high affinity for the gold surface, is present around the nanoparticles before a protein corona is formed in bovine serum, the cellular uptake is significantly increased with an inhibition of ROS. The selective sequential pre-formation of protein complexes prior to incubation in cells is demonstrated as a viable method to alter the biological behaviour of nanoparticles.

Nanodiamonds form a dynamic protein corona independent of the type of surface functional group. Proteomics data suggest that the top 30 proteins of nanodiamonds that are incubated in fetal bovine serum are similar in terms of abundance and function, despite differences in the nanodiamond surface properties. Surprisingly, the most abundant serum protein, albumin, is not one of the most abundant corona proteins, with low molecular weight proteins below 20 kDa being favoured. The pre-incubation of a protein corona on nanodiamonds significantly decreases the production of reactive oxygen species, increasing the cell viability of macrophages after incubation with the nanodiamonds for 48 hours. However, this effect was only observed for protein coronas on nanodiamonds with a negative surface charge and not when they were functionalised with positive surface charges, such as amine groups. This work highlights the role of the protein corona in colloidal stability and its effect on the biological behaviour of diamond nanoparticles.

The mesoporous solid SBA-2, prepared at room temperature in alkaline pH using the gemini surfactant [CH3(CH2)15N(CH3)2(CH2)3N(CH3)3]2+ can adopt hollow sphere (ca. 100 μm diameter), flat plate (50 μm across) and small sphere (1–2 μm diameter) morphologies. Plates appear to be formed directly by fracturing of the hollow spheres. The nanostructure of these materials is consistent with templating around close packed micelles. X-Ray diffraction and high resolution imaging show that the structure of these preparations ranges from mainly hexagonal to mainly cubic close packing.

The release of the hydrophobic cancer drug dasatinib from two mesoporous silica materials as drug delivery vehicles has been studied. One material is a reference 2D-hexagonal SBA-15 with the typical bimodal pore system with ordered primary mesopores and disordered intrawall pores. The other material is a modified version of the same material where the intrawall porosity in the micropore regime has been selectively removed. Material characterization shows that, with the exception of the difference in intrawall porosity, the materials have identical properties. The drug dasatinib, a tyrosine kinase inhibitor, has been loaded, to the same extent, into the pores of both materials. The two materials give rise to very different release profiles of the drug. The presence of micropores leads to desired release properties: a high initial release of the drug, which is maintained over time. The lack of micropores also leads to a high initial release but followed by a rapid drop in the concentration of released drug, a consequence of its low solubility and hence crystallisation. We suggest that the presence of micropores in the carrier material, and the resultant kinetic release profile, leads to a stabilization of dasatinib in solution and to a sustained supersaturated level of the released drug. Our findings suggest that by controlling the mesoporous host with small variation in the textural properties, the kinetic release and crystallization behaviour of a drug can be altered. It is thus potentially possible to influence the drug post-release and thereby its bioavailability.

An in-depth study of the synthesis and growth of bicontinuous cubic mesoporous AMS-6 material in the presence of polymeric dispersant P123 is presented, resulting in controlled particle shape attainable over a small range of synthesis conditions. Unlike previous syntheses a remarkable effect on facet formation of the Iad silica particles with cubic morphologies is observed. Trapezoidal icositetrahedra, spherical and elongated morphologies have been prepared with increased faceting on addition of higher concentration of dispersant. Particles are characterised extensively by powder X-ray diffraction, transmission electron microscopy, scanning electron microscopy and nitrogen sorption isotherms. Mesoporous materials produced in this study show textural features suggesting a secondary porous network formed on the external surface of the particle and the origin of this secondary porosity is discussed. Based on the reduced dynamics generated by the presence of the P123 dispersant, we suggest possible growth models for the formation of mainly two different morphologies—the thermodynamically favoured trapezoidal icositetrahedron and elongated particles, the latter not following the expected point group symmetry, mm.