Biomedical subjects

Merugu Srinivas

Publications and source records attributed to Merugu Srinivas.

3 recordsLinked to original sources

PubMed2006

Effect of carrier ionic strength in microscale cyclical electrical field-flow fractionation.

Recent work with cyclical electrical field-flow fractionation systems has shown promise for the technique as a separation and analysis tool, but little is understood about how the carrier composition in the system affects its capabilities. The electrical properties of microscale CyElFFF systems change when the carrier ionic conditions are altered, and it is well known that the effects of increasing ionic strength carriers on retention in normal ElFFF systems are severe. Specifically, retention levels fall significantly. Accordingly, this work seeks to understand the effect that increasing carrier ionic strength in CyElFFF has on nanoparticle retention in the channels. The retention of polystyrene particles in the CyElFFF microsystem is reported at various ionic strengths of ammonium carbonate and at a variety of pH levels. The experiments are compared to the theory of CyElFFF available in the literature. The results indicate that the ionic strength of the carrier has a significant impact on retention and that high ionic strength carrier solutions lead to poor performance of the CyElFFF system. These results have significant impact on the possible uses of the technique and its applications, especially in the biomedical arena.

Journal Article↗

PubMed2006

Characterization of a microscale cyclical electrical field flow fractionation system.

A microscale cyclical electrical field flow fractionation (CyElFFF) channel is characterized with regard to the effect of various operating parameters and comparison made to recent theoretical developments. Challenges associated with various operating conditions are reported along with some of the optimized operating parameters. The effect of retention wall choice, an offset voltage, relaxation steps, and flow rates, along with the basic operating parameters of voltage, frequency, and electrophoretic mobility are reported. Retention of polystyrene nanoparticle standards is accomplished and the first separations using this technique in a microscale system are also demonstrated. Relaxation steps and offset voltages are found to be effective in eliminating early peaks and in improving plate heights. Plate heights were also found to decrease with increasing flow rates, which is the opposite of the behavior seen in most existing chromatographic systems. The experimental results are compared to the analytical and empirical models of CyElFFF and found to be compatible. Suggestions are made for improving the separation and analysis methods used with CyElFFF.

Journal Article↗

PubMed2005

Cyclical electrical field flow fractionation.

Cyclical electrical field flow fractionation (Cy/ElFFF) is demonstrated in a standard electrical field flow fractionation (ElFFF) channel for the first time. Motivation for the use of alternating current (AC) fields in a traditionally direct current (DC) technique are discussed. The function of the system over a wide range of operating conditions is explored and challenges associated with various operating conditions reported. Retention of polystyrene nanoparticle standards is accomplished and the effect of varying parameters of the applied field, such as voltage and frequency, are explored. The first separations using this technique are demonstrated. The experimental results are compared to analytical models previously reported in the literature. The general trend of the experimental results is similar to those predicted in theoretical models and possible reasons for discrepancies are elucidated. Suggestions are made for improving the separation and analysis method, and possible applications explored.

Electrophoresis↗