Nanoparticle imaging and diagnostic of Caenorhabditis elegans intracellular pH.

A novel diagnostic tool has been developed for the characterization of intracellular pH (pHi) in the model organism Caenorhabditis elegans. This tool exploits the chemical stability of colloidal silica and the pH sensitivity of certain fluorescent dyes. Once ingested, the fluorescent colloidal dispersion yields a reliable visual indication of pH without the use of chemical fixatives or damaging the nematode.

Development of encoded particle-polymer arrays for the accelerated screening of antifouling layers.

A multiplexed screening methodology for the rapid development of antifouling polymer surfaces is presented. An array of protein resistant polymer layers with high grafting (>100 mg m(-2)) were polymerized on optically encoded particles. Multiplexed analysis showed a 97% reduction in nonspecific protein adsorption for all polymer layers created.

Effect of poly(ethylene glycol) (PEG) spacers on the conformational properties of small peptides: a molecular dynamics study.

Poly(ethylene glycol) (PEG) is used as an inert spacer in a wide range of biotechnological applications such as to display peptides and proteins on surfaces for diagnostic purposes. In such applications it is critical that the peptide is accessible to solvent and that the PEG does not affect the conformational properties of the peptide to which it is attached. Using molecular dynamics (MD) simulation techniques, we have investigated the influence of a commonly used PEG spacer on the conformation properties of a series of five peptides with differing physical-chemical properties (YGSLPQ, VFVVFV, GSGGSG, EEGEEG, and KKGKKG).

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.

Improving the signal-to-noise performance of molecular diagnostics with PEG-lysine copolymer dendrons.

The synthesis, characterization, and use of dendron-like poly(ethylene glycol)-lysine (PEG-Lys) copolymers as an intermediate layer for biomolecular diagnostic signal enhancement is presented. Solid phase Fmoc-peptide synthesis was used to synthesize polymers with one, two, and three PEG-Lys comonomer units in both a linear and first and second-generation dendronic structure directly onto organosilica microspheres. The microsphere surface loadings (number of free amine sites) were modified and quantified through an innovative use of the protecting groups of coupled amino acids.

Flow cytometric detection of proteolysis in peptide libraries synthesised on optically encoded supports.

The concept of optically encoding particles for solid phase organic synthesis has existed in the literature for several years. However, there remains a significant challenge to producing particles that are capable of withstanding harsh solvents and reagents whilst maintaining the integrity and range of the optical encoding. In this study, a new generation of fluorescently encoded support particles was used for both solid phase peptide synthesis and on-particle analysis of proteolysis in a multiplexed, flow cytometric assay.

Tailoring surface properties to build colloidal diagnostic devices: controlling interparticle associations.

The ability to control the surface properties and subsequent colloidal stability of dispersed particles has widespread applicability in many fields. Sub-micrometer fluorescent silica particles (reporters) can be used to actively encode the combinatorial synthesis of peptide libraries through interparticle association. To achieve these associations, the surface chemistry of the small fluorescent silica reporters is tailored to encourage robust adhesion to large silica microparticles onto which the peptides are synthesized.

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.

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.