Plasma etched polymer microelectrochemical systems.

This paper presents a novel technique based on plasma etching for the mass production of polymer microchip devices. The method consists of the patterning of a photo-resist by a high resolution printer on a foil composed of three layers (5 microm copper/50 microm polyimide/5 microm copper). After this step, both copper layers are chemically etched in order to serve as a contact mask on the polyimide surface so as to produce the desired microstructure pattern.

Integration of a membrane-based desalting step in a microfabricated disposable polymer injector for mass spectrometric protein analysis.

A simple desalting procedure for the coupling of a polymer microchip injector to mass spectrometry is proposed. The overall process is based on the adsorption of proteins on a poly(vinylidene difluoride) (PVDF) membrane, which are then directly eluted in the spraying solution. This microchip-based approach has been successfully applied to small drugs, peptides and proteins originally diluted in phosphate-buffered saline (PBS).

Theoretical and experimental exploration of the lipophilicity of zwitterionic drugs in the 1,2-dichloroethane/water system.

Purpose: This work examines the lipophilic behavior of various zwitterions and shows how distribution profiles in biphasic systems and ionic partition diagrams may improve our understanding of pH-absorption profiles of drugs.

Methods: The lipophilicity of various zwitterionic drugs was examined by potentiometry and cyclic voltammetry in the 1,2-dichloroethane/water system to study the intramolecular interactions and conformational effects affecting absorption and activity of zwitterions, as well as to draw their theoretical and experimental ionic partition diagrams.

Results: Different theoretical partition diagrams are reported according to the tautomeric constant of the zwitterion.

Lipophilicity and solvation of anionic drugs.

This paper first gives a brief review of the main techniques used to measure the lipophilicity of neutral and ionic drugs, namely the shake-flask method, potentiometry, and cyclic voltammetry at liquid-liquid interfaces. The lipophilicity of 28 acidic compounds with various functional groups was studied by potentiometry and cyclic voltammetry in the n-octanol/water and 1,2-dichloroethane/water systems in order to complement our understanding of the lipophilicity of neutral and ionized acids and to clarify the solvation mechanisms responsible for their partition. The parameter diff (log P(N-A)(dce)) (i.

Microfabricated polymer injector for direct mass spectrometry coupling.

This paper demonstrates the coupling of a plasma etched polymer microfluidic system with an electrospray mass spectrometer by generation of a nanospray. Taking advantage of the microtechnology processes and polymer properties, high volume production with good reproducibility of hydrophobic interfaces could be obtained. The nanospray was directly produced from the outlet of the plastic microfabricated chip positioned in front of the capillary entrance of the mass spectrometer.