A Method for Simultaneous Polishing and Hydrophobization of Polycarbonate for Microfluidic Applications.

Here we present a new methodology for chemical polishing of microchannels in polycarbonate (PC). Tuning the time of exposition and the concentration of ammonia, the roughness arising from the micromachining process can be significantly reduced or completely removed while preserving the structure of microchannels. Besides smoothing out the surface, our method modifies the wettability of the surface, rendering it hydrophobic.

An FEP Microfluidic Reactor for Photochemical Reactions.

Organic syntheses based on photochemical reactions play an important role in the medical, pharmaceutical, and polymeric chemistry. For years, photochemistry was performed using high-pressure mercury lamps and immersion-wells. However, due to excellent yield, control of temperature, selectivity, low consumption of reagents and safety, the microreactors made of fluorinated ethylene propylene (FEP) tubings have recently been used more frequently.

Polyethyleneimine coating renders polycarbonate resistant to organic solvents.

We propose a method for the modification of surfaces of microchannels in chips fabricated in polycarbonate (PC) that makes the devices resistant to a range of organic solvents. Coating of PC with branched polyethyleneimine (BPEI) with the use of trimethylpropane triglycidyl ether (TTE) as a linker renders the devices resistant to toluene, benzene, acetonitrile, tetrahydrofuran, dioxane and ethylene dichloride. The optimized procedure of modification allows for continuous operation of the chips for several hours without dissolution of PC.

Hydrophobic modification of polycarbonate for reproducible and stable formation of biocompatible microparticles.

We propose a simple and effective scheme for the modification of the walls of microfluidic channels fabricated in polycarbonate (PC) after the device has been bonded. The method prevents both static and dynamic wetting of PC by aqueous solutions including viscous, non-Newtonian solutions of polymers as e.g.

An automated potentiometric assay for acid phosphatase.

Two flow injection systems for detection of acid phosphatase (ACP) activity have been investigated. In both systems, monofluorophosphate (MFP) as a specific and inexpensive substrate for ACP and LaF(3) membrane-based ion-selective electrode as a potentiometric detector of fluoride ions released in the course of the biocatalytic hydrolysis of MFP were applied. The continuous-flow mode was modified to include a stopped-flow segment, with separate valve control, to increase reaction time and minimize dispersion while increasing system throughput.

Potentiometric flow-injection system for determination of alkaline phosphatase in human serum.

A flow-injection system for detection of alkaline phosphatase (ALP) activity in human serum samples has been developed. As a specific and inexpensive ALP substrate for this kinetic assay monofluorophosphate (MFP) was applied. For detection of fluoride ions, generated in the course of the biocatalytic hydrolysis of MFP, conventional fluoride ion-selective electrode based on LaF(3)-crystalline membrane was applied.