Cancer-targeting siRNA delivery from porous silicon nanoparticles.

Aims: Porous silicon nanoparticles (pSiNPs) with tunable pore size are biocompatible and biodegradable, suggesting that they are suitable biomaterials as vehicles for drug delivery. Loading of small interfering RNA (siRNA) into the pores of pSiNPs can protect siRNA from degradation as well as improve the cellular uptake. We aimed to deliver MRP1 siRNA loaded into pSiNPs to glioblastoma cells, and to demonstrate downregulation of MRP1 at the mRNA and protein levels.

Nanoporous alumina-based interferometric transducers ennobled.

A high fidelity interferometric transducer is designed based on platinum-coated nanoporous alumina films. The ultrathin metal coating significantly improves fidelity of the interferometric fringe patterns in aqueous solution and increases the signal-to-noise ratio. The performance of this transducer is tested with respect to refractive index unit (RIU) sensitivity measured as a change in effective optical thickness (EOT) in response to a solvent change and compared to porous silicon based transducers.

Porous silicon biosensors on the advance.

Biosensor research is a rapidly expanding field with an immense market potential spanning a broad spectrum of applications including biomedical diagnostics, environmental monitoring, veterinary and food quality control. Porous silicon (pSi) is a nanostructured material poised to take centre stage in the biosensor development effort. This can be ascribed to the ease and speed of fabrication, remarkable optical and morphological properties of the material (including tuneable pore size and porosity), large internal surface area and the versatile surface chemistry.

Self-assembly of electro-active protein architectures on electrodes for the construction of biomimetic signal chains.

The layer-by-layer adsorption technique based on the consecutive deposition of oppositely charged species is suitable for the preparation of protein multilayers with fully electro-active protein molecules. The methodology was established with cytochrome c and the polyelectrolyte sulfonated polyaniline (PASA). The technique is also useful for the construction of bi-protein architectures confining protein-protein communication to an electrode.

Electrocatalytic sulfite biosensor with human sulfite oxidase co-immobilized with cytochrome c in a polyelectrolyte-containing multilayer.

An efficient electrocatalytic biosensor for sulfite detection was developed by co-immobilizing sulfite oxidase and cytochrome c with polyaniline sulfonic acid in a layer-by-layer assembly. QCM, UV-Vis spectroscopy and cyclic voltammetry revealed increasing loading of electrochemically active protein with the formation of multilayers. The sensor operates reagentless at low working potential.

Self-assembly of S-layer-enveloped cytochrome c polyelectrolyte multilayers.

We report a study of the electrostatic layer-by-layer self-assembly of electroactive polyelectrolyte multilayers incorporating the redox protein cytochrome c (cyt c) combined with recrystallization of the bacterial cell wall surface layer from Bacillus sphaericus CCM 2177 SbpA (S-layer). The polyelectrolyte multilayer assembly was prepared on flat gold electrodes with a nanometer-scale roughness that allowed monitoring of the film formation throughout all the assembly stages by atomic force microscopy measurements in liquid with respect to topography and forces. The deposition of alternating layers of sulfonated polyaniline and cyt c was carried out by adsorption from the corresponding solutions on a cyt c monolayer electrode.

Electrocatalytically functional multilayer assembly of sulfite oxidase and cytochrome c.

An electrocatalytically functional multilayer has been designed using two proteins, cytochrome c and sulfite oxidase, and a polyelectrolyte (polyaniline sulfonate). The two proteins were co-immobilized on the surface of a gold electrode in alternating layers by electrostatic interactions using the layer-by-layer technique. The formation of this fully electro-active multilayer is characterized by quartz crystal microbalance and electrochemical experiments.

Electron transfer in SAM/cytochrome/polyelectrolyte hybrid systems on electrodes: a time-resolved surface-enhanced resonance Raman study.

Silver electrodes were covered with mixed self-assembled monolayers (SAMs) of 11-mercaptoundecanoic acid (MUA) and 11-mercaptoundecanol (MU) and subsequently coated with alternating layers of cytochrome c (Cyt) and poly(anilinesulfonic acid) (PASA). The immobilized protein is electroactive and retains its native structure. Compared to the case of systems on gold electrodes, the stability of the assembly was found to be decreased.