High-throughput and combinatorial gene expression on a chip for metabolism-induced toxicology screening.

Differential expression of various drug-metabolizing enzymes (DMEs) in the human liver may cause deviations of pharmacokinetic profiles, resulting in interindividual variability of drug toxicity and/or efficacy. Here, we present the 'Transfected Enzyme and Metabolism Chip' (TeamChip), which predicts potential metabolism-induced drug or drug-candidate toxicity. The TeamChip is prepared by delivering genes into miniaturized three-dimensional cellular microarrays on a micropillar chip using recombinant adenoviruses in a complementary microwell chip.

Regulation of stem cell signaling by nanoparticle-mediated intracellular protein delivery.

Intracellular delivery of specific proteins and peptides may be used to influence signaling pathways and manipulate cell function, including stem cell fate. Herein, we describe the delivery of proteins attached to hydrophobically modified 15-nm silica nanoparticles to manipulate specifically targeted cell signaling proteins. We designed a chimeric protein, GFP-FRATtide, wherein GFP acts as a biomarker for fluorescence detection, and FRATtide binds to and blocks the active site of glycogen synthase kinase-3β (GSK-3β) - a protein kinase involved in Wnt signaling.

A GFP complementation system for monitoring and directing nanomaterial mediated protein delivery to human cellular organelles.

Protein-based therapeutics are gaining importance for their biocompatibility and activity toward specific targets. When these targets are intracellular, it is critical to deliver biomolecules to sites in the cell cytoplasm while retaining biomolecule activity in the complex cellular milieu. However, intracellular protein delivery is not viable unless accompanied by an active uptake mechanism or carrier mediated delivery.

Nanoparticle-mediated cytoplasmic delivery of proteins to target cellular machinery.

Despite recent advances in nanomaterial-based delivery systems, their applicability as carriers of cargo, especially proteins for targeting cellular components and manipulating cell function, is not well-understood. Herein, we demonstrate the ability of hydrophobic silica nanoparticles to deliver proteins, including enzymes and antibodies, to a diverse set of mammalian cells, including human cancer cells and rat stem cells, while preserving the activity of the biomolecule post-delivery. Specifically, we have explored the delivery and cytosolic activity of hydrophobically functionalized silica nanoparticle-protein conjugates in a human breast cancer cell line (MCF-7) and rat neural stem cells (NSCs) and elucidated the mechanism of cytosolic transport.

Structure, function, and stability of enzymes covalently attached to single-walled carbon nanotubes.

We describe the structure, activity, and stability of enzymes covalently attached to single-walled carbon nanotubes (SWNTs). Conjugates of SWNTs with three functionally unrelated enzymes-horseradish peroxidase, subtilisin Carlsberg, and chicken egg white lysozyme-were found to be soluble in aqueous solutions. Furthermore, characterization of the secondary and tertiary structure of the immobilized proteins by circular dichroism and fluorescence spectroscopies, respectively, and determination of enzyme kinetics revealed that the enzymes retained a high fraction of their native structure and activity upon attachment to SWNTs.