Multifunctionalized Biocompatible Microspheres for Sensing

Abstract

We present our achievements in the synthesis and application of multifunctionalized, cross-linked, polystyrene microspheres, which remarkably and quite generally are taken up by all cell types studied to date. Importantly, the nature of these synthetic beads allows multistep solid-phase chemistry and the ability to bind essentially any molecule/sensor/nucleic acid to them. These microspheres have a number of advantages over other cellular delivery approaches. First, a diverse range of compounds can be attached to the microspheres, and we have demonstrated that these materials are effectively delivered into cells; second, the cellular cargo can be modulated through modification of bead loading; third, they are large enough to be visualized using standard microscopy techniques; and fourth, their cargos are not diluted within the cell. Populations of cells containing beads can be readily sorted from other cells for subsequent analysis with very high, but controllable, uptake rates, which can be modulated through modulation of the bead size and incubation time. Recent work has focused on the development of these microspheres as sensors for intracellular calcium and pH.

Allosteric inhibition of individual enzyme molecules trapped in lipid vesicles

“…In contrast, we discovered that molecules of the product resorufin cannot cross the phospholipid bilayer at neutral pH due to their negative charge (45), which leads to their accumulation in the vesicle interior. Product generation by individual enzyme molecules could, therefore, be determined by monitoring the increase in fluorescence as the reaction progressed, following its initiation by adding Amplex Red and the cosubstrate H 2 O 2 to surface-tethered vesicles.…”

Porous Silicon Microcavities Based Photonic Barcodes

“…In the last years a great interest has been paid to the development of micro-and nanometer size particles and systems able to act as photonic sensors, [ 15 , 21-22 ] and encoders [ 16 , 23 ] for medicine [ 24 ] and biology. Some very promising approaches are based on different materials as polystyrene [ 22 ] and silica beads, [ 25 , 26 ] or plasmonic [ 27 , 28 ] nanoparticles, doped with either luminescent organic dyes [ 21 ] or semiconducting quantum dots (QD) as CdSe. [ 29 ] The use of dye doped particles has the advantage of a large luminescent quantum yield.…”

Porous silicon microcavities: synthesis, characterization, and application to photonic barcode devices

“…In the last years, great interest has been paid to the development of micro- and nanometer-sized particles and systems able to act as photonic sensors [15,22,23] for medicine [24] and biology. As porous silicon-based sensors are biocompatible [15], stable [25], and biodegradable [26], photonic barcodes are envisaged for being used in the fields of biology and medicine.…”