Conventional micro-surgical tools are tethered since they are actuated by electrical or pneumatic signals. As a first step towards the creation of autonomous mobile surgical tools, we have developed "mobile" tetherless microgrippers that were shown to close and excise tissue when exposed to heat or certain biochemicals.

Nanoparticles from novel porphyrinoid compounds have been prepared via a self-assembly process involving a host-guest solvent mixing strategy. The molecular building blocks, called corrolazines, are ring-contracted forms of porphyrins that exhibit intriguing physical properties and chemical behavior.

We use Langmuir-Blodgett deposition and vesicle fusion to form supported bilayer membranes on single crystal silicon. Peptides can be incorporated during LB deposition. Electrochemical impedance spectroscopy is used to characterize the electrical properties of the membranes.

This technique measures the dynamic binding interactions between glycoproteins on a viral envelope and receptors on the surface of the cell. Analysis of the data allows us to map the tensile strengths, lifetimes, and energy barriers of individual intermolecular bonds between CCR5 tropic HIV-1 gp120 and its receptors CD4 and CCR5 or CXCR4 as a function of the interaction time.

This method measures the kinetics and micromechanical properties of individual receptor-ligand bonds formed between two living cells. Using living cells rather than recombinant proteins ensures that the orientation, surface density, and post-translational modifications of the probed receptors are physiological and that their regulated attachment to the cytoskeleton can occur. A cell is tethered to a flexible cantilever and brought into contact with cells adherent to a substratum before being pulled at a controlled retraction velocity. Measurements of bond rupture forces and associated bond loading rates over an extended range of retraction velocities allow us to compute precisely the tensile strength, reactive compliance, lifetime, and dissociation rate of individual intercellular receptor-ligand bonds.

This a method to measure the local and global micromechanical properties of the cytoplasm of single living cells in their physiological milieu and subjected to external stimuli. By tracking spontaneous, Brownian movements of individual nanoparticles of diameter ? 100 nm distributed within the cell with high spatial and temporal resolutions, the local viscoelastic properties of the intracellular milieu can be measured in different locations within the cell.

Mesenchymal cell migrating through a three-dimensional (3-D) matrix typically involves major matrix remodeling. The direction of matrix deformation occurs locally in all 3 dimensions, which cannot be measured by current techniques. To probe the local, 3-D, real-time deformation of a collagen matrix during tumor cell migration, we have developed a new assay where matrix-embedded beads are tracked simultaneously in all 3 directions with high resolution.

We are synthesizing CdSe and CdTe QDs with diameters up to about 10 nm. The addition of a ZnS passivation layer increases the quantum yield. We have developed protocols to transfer the QDs to water and to control the surface coverage of fluorophores and antibodies.

Electrochemically programmed release (EPR) is a tool for release of immobilized molecules (e.g. drugs, proteins, DNA, and viruses) and nanoparticles from an electrode surface in response to a small voltage pulse. Spatial and temporal control can be achieved using microfabrication techniques.