Organosilica Microspheres Research Articles

Modification and optimization of organosilica microspheres for peptide synthesis and microsphere-based immunoassays

A new generation of optically encoded organosilica microspheres, suitable for both solid phase synthesis and multiplexed microsphere-based assays, has recently been described. One of the challenges of producing this type of dual-purpose solid support is that the particles must maintain their morphology as well as their encoding during exposure to the solvents used for solid phase synthesis. In this article, organosilica microspheres are subjected to ammonia treatment methods for enhancing the condensation of the silica matrix and their subsequent resilience toward organic solvents and peptide synthesis reagents is described. The instability of the untreated supports toward organic synthesis reagents was found to be associated with the swelling and permeability of these microspheres in organic solvents. Post-synthesis ammonia treatment resulted in reduced permeability, as demonstrated by dye uptake studies. The treated microspheres exhibited enhanced stability against organic synthesis conditions and were characterized via a variety of techniques including electron microscopy, (29)Si-nuclear magnetic resonance (NMR) and optical microscopy. The ammonia-treated supports were subjected to an Fmoc peptide synthesis procedure and successfully applied in a model microsphere-based flow cytometric immunoassay.

Mesoporous maghemite–organosilica microspheres: a promising route towards multifunctional platforms for smart diagnosis and therapy

We report facile fabrication of advanced hybrid silica–spinel iron oxide (maghemite) composite microspheres built with both superparamagnetic nanoparticles for MR imaging, hyperthermia, and a hybrid mesoporous matrix enabling the transport of bioactive molecules for in vivo biomedical applications. Elaboration of such multifunctional platforms is performed by spray drying a sol of tunable composition that allows one to control the size and amount of magnetic particles embedded in the matrix, without aggregation, and to adjust the size and the surface chemical properties of the porous silica cavities. The resulting nanocomposites (γ-Fe2O3 8 nm particles in silica matrices from TEOS templated by CTAB or P123, without or with functionalisation with –Ph, –SH or –NH2) were characterised by chemical analysis, XRD, TEM, BET, FTIR and magnetisation measurements. Tests of the materials both as MRI T2-contrast agents and as heating sources of hyperthermia are presented in support of potential applications in diagnosis and therapy.

Functionalized Organosilica Microspheres via a Novel Emulsion-Based Route

Thiol-functionalized organosilica microspheres were synthesized via a two-step process: (1) acid-catalyzed hydrolysis and condensation of 3-mercaptopropyltrimethoxysilane (MPTMS), followed by (2) base-catalyzed condensation, which led to the rapid formation of emulsion droplets with a narrow size distribution. These droplets continued to condense to form solid microspheres. Solution (29)Si NMR and optical microscopy were applied to study the mechanism of this novel synthetic route. Solid-state (29)Si NMR, SEM, zeta potential titration, and Coulter counter measurements were used to study the bulk and surface properties and to determine the particle size distributions of the final microspheres. Compared to conventional Stöber silica particles, these microspheres were shown to have a lower degree of cross-linking (average degree of condensation, r = 1.25), a larger average size (up to 6 microm), and a higher isoelectric point (pH = 4.4). Confocal microscopy of dye-labeled microspheres showed an even distribution of dye molecules throughout the interior, characteristic of a readily accessible and permeable organosilica network. These findings have implications for the production of functionalized solid supports for use in catalysis and biological applications, such as optically encoded carriers for combinatorial synthesis.

Biomolecular screening with novel organosilica microspheres

Organosilica microspheres synthesised via a novel surfactant-free emulsion-based method show applicability towards optical encoding, solid-phase synthesis and high-throughput screening of bound oligonucleotide and peptide sequences.

Synthesis of super-microporous organosilica microspheres through in situ self-assembly of nanoparticles

Super-microporous organosilica microspheres have been first synthesized using polyoxyethylene (23) lauryl ether (Brij-35) as the template and 1,2-bis(trimethoxysilyl)ethane (BTME) as the organosilica source through a salt-assisted self-assembly method under static and acid conditions.