Biomedical subjects

Melissa S Hasenbank

Publications and source records attributed to Melissa S Hasenbank.

3 recordsLinked to original sources

PubMed2006

Lateral spread of an amplification signal using an enzymatic system on a conductive surface.

In this letter, we report a novel signal amplification phenomenon that rapidly and dramatically increases both the magnitude and the lateral extent of the original signal. This phenomenon utilizes an enzyme immobilized on a conductive surface to generate amplified signals at locations remote from the original site of enzyme activity. The result is demonstrated on a microfluidic platform using the established precipitating enzyme-substrate system of horseradish peroxidase (HRP) and 3,3',5,5'-tetramethylbenzidine (TMB) on a surface plasmon resonance (SPR) imaging system.

Electric Conductivity↗

PubMed2005

Diffusion based analysis in a sheath flow microchannel: the sheath flow T-sensor.

This paper describes a microfluidic channel that allows for diffusion-based analysis of adsorbing species without passivation of the channel surfaces. The sheath flow configuration was used to measure the diffusion coefficient of fluorescently labeled species from their spatial distribution within the microchannel by analyzing the derivative of the intensity profile at the interface between two distinct core fluids. Measurements for both a small molecule (rhodamine B) and an intermediate-sized protein (wheat germ agglutinin) were made, demonstrating the utility of the sheath flow T-sensor.

Diffusion↗

PubMed2004

Suppression of non-specific adsorption using sheath flow.

The use of a confining sheath fluid within a microfluidic channel in order prevent non-specific adsorption of analytes to the walls of microchannels is demonstrated. A sheath-flow channel fabricated using laser cutting of Mylar films is developed. Numerical simulations of convective and diffusive mass transport within the channel are presented. The device is characterized experimentally using epifluorescence microscopy. It is demonstrated that the device is capable of preventing the adsorption of Rhodamine B to the walls of the channel for a period that would allow for adsorption-free T-sensor measurements to be made within the core of the flow channel. Generalized scaling rules based on the diffusion coefficient, sheath thickness and affinity of the potential adsorbant for the surface material are discussed. The controlled adsorption of the protein bovine serum albumin (BSA) to a gold surface is also demonstrated using SPR microscopy.

Adsorption↗