Multistage Isoelectric Focusing: A Novel On-Chip Bio-Separation Technique

2005 ◽  
Author(s):  
Prashanta Dutta ◽  
Keisuke Horiuchi ◽  
Huanchun Cui ◽  
Cornelius F. Ivory
Keyword(s):  
Isoelectric Focusing ◽  
Microfluidic Chip ◽  
Soft Lithography ◽  
Fluorescent Protein ◽  
Ph Gradient ◽  
Resolving Power ◽  
Protein Species ◽  
Second Stage ◽  
On Chip ◽  
Bonding Technique

This experimental study reports a method to increase the resolving power of isoelectric focusing (IEF) on a polymeric microfluidic chip. Microfluidic chip is formed on poly-di-methyl siloxane (PDMS) using soft lithography and multilayer bonding technique. In this novel bioseparation technique, IEF is staged by first focusing protein species in a straight channel using broad-range ampholytes and then refocusing segments of that first channel into secondary channels that branch out from the first one. Experiments demonstrated that three fluorescent protein species within a segment of pH gradient in the first stage were refocused in the second stage with much higher resolution in a shallower pH gradient. A serially performed two-stage IEF was completed in less than 25 minutes under particularly small electric field strength up to 100 V/cm.

Chromatofocusing and isoelectric focusing in immobilized pH gradients compared for characterization of human hemoglobin variants.

1989 ◽  
Vol 35 (3) ◽  
pp. 425-430 ◽  
Author(s):  
R Paleari ◽  
C Arcelloni ◽  
R Paroni ◽  
I Fermo ◽  
A Mosca
Keyword(s):  
Los Angeles ◽  
Isoelectric Focusing ◽  
Ph Gradient ◽  
Resolving Power ◽  
Human Hemoglobin ◽  
Ph Gradients ◽  
Hemoglobin Variants

Abstract We compared the performance of two highly resolving methods, chromatofocusing (CRF) and isoelectric focusing in immobilized pH gradients (IPGF), for the separation of human hemoglobin variants. Lysates containing 13 different hemoglobins, including variants of clinical and geographical importance, and four electrophoretically "silent" variants (Hb Brockton, Hb Cheverly, Hb Köln, and Hb Waco) were analyzed. Both techniques showed a good intrarun precision (CV = 0.87% for CRF, 0.27% for IPGF) and high and similar resolving power (0.010 pH units, with the pH gradients used in this work). The use of an ultranarrow IPGF range (pH 7.15-7.35; pH gradient = 0.019 pH/cm) allowed the resolution between Hb Brockton, Hb Köln, and Hb A. In some cases (Hb D-Los Angeles, Hb F, Hb Waco), the variants were separated from Hb A in different orders, depending on which technique was used, probably because of the different analytical principles of the two methods. As a second-level test, both procedures are informative for characterization of human hemoglobin variants.

Integrated Microfluidic Flow Sensor for LAB-oN-CHIP and PoINT-oF-CARE Applications

2020 ◽  
Vol 36 (4) ◽  
pp. 112-120
Author(s):  
A.V. Zverev ◽  
M. Andronik ◽  
V.V. Echeistov ◽  
Z.H. Issabayeva ◽  
O.S. Sorokina ◽  
...  
Keyword(s):  
Numerical Simulation ◽  
Flow Rate ◽  
Microfluidic Chip ◽  
Soft Lithography ◽  
Point Of Care ◽  
Flow Sensor ◽  
Oxide Semiconductor ◽  
Dead Volume ◽  
Lab On Chip ◽  
On Chip

The results of the development and manufacture of an integrated membrane-free sensor for the control of accurate dilution of liquid samples on the microfluidic chip are presented. The proposed type of devices is intended for direct precise measurements of liquid flow rate in microchannels of laboratories-on-chip, including point-of-care systems. The sensor topology was optimized based on the numerical simulation results and technological requirements. The main characteristic of the developed sensor is the lack of a membrane in the design while maintaining the sensitivity and accuracy of the device at the level of a commercial membrane analogue. The fully biocompatible sensor was manufactured using standard microelectronics and soft lithography technologies. In order to optimize the sensor design, 32 different topologies of the device were tested. The integration of the flow sensors on the chip allows to significantly reduce the dead volume of the hydrodynamic system and to control the amount of liquid entering the individual reservoirs of the microfluidic chip. The sensor occupies an area of (210 x 140) um2 in the channel and is characterized by a relative error of 5% in the flow rate range of 100-1000 ul/min. microfluidics, lab-on-chip, calorimetric flow sensor, thermoresistive sensor, numerical simulation, hydrodynamics, complementary metal-oxide-semiconductor, microtechnologies Devices were made at the BMSTU Nanofabrication Facility (FMN Laboratory, FMNS REC, ID 74300).

On-chip protein isoelectric focusing using a photoimmobilized pH gradient†

2014 ◽  
Vol 37 (21) ◽  
pp. 3174-3180 ◽  
Author(s):  
Lin Xia ◽  
FengMing Lin ◽  
Xin Wu ◽  
Chuanli Liu ◽  
Jianshe Wang ◽  
...  
Keyword(s):  
Isoelectric Focusing ◽  
Ph Gradient ◽  
On Chip

scholarly journals On-chip protein isoelectric focusing using a photo-immobilized pH gradient

2014 ◽  
Vol 37 (21) ◽  
pp. NA-NA
Author(s):  
Lin Xia ◽  
FengMing Lin ◽  
Xin Wu ◽  
Chuanli Liu ◽  
Jianshe Wang ◽  
...  
Keyword(s):  
Isoelectric Focusing ◽  
Ph Gradient ◽  
On Chip

Instability and non-linearity of the pH gradient formed in isoelectric focusing

1979 ◽  
Vol 174 (1) ◽  
pp. 1-11 ◽  
Author(s):  
A. Murel ◽  
I. Kirjanen ◽  
O. Kirret
Keyword(s):  
Isoelectric Focusing ◽  
Ph Gradient

Focusing of Proteins in a Horseshoe Microchannel

2008 ◽  
Author(s):  
Jaesool Shim ◽  
Prashanta Dutta ◽  
Cornelius F. Ivory
Keyword(s):  
Capillary Electrophoresis ◽  
Electric Field ◽  
Isoelectric Focusing ◽  
Ph Gradient ◽  
Complex Geometries ◽  
Electrokinetic Phenomena ◽  
Double Peaks ◽  
Zone Electrophoresis ◽  
Carrier Ampholytes ◽  
Ph Range

Ampholyte based isoelectric focusing (IEF) simulation was conducted to study dispersion of proteins in a horseshoe microchannel. Four model proteins (pls = 6.49, 7.1, 7.93 and 8.6) are focused in a 1 cm long horseshoe channel under an electric field of 300 V/cm. The pH gradient is formed in the presence of 25 biprotic carrier ampholytes (ΔpK = 3.0) within a pH range of 6 to 9. The proteins are focused at 380 sec in a nominal electric field of 300 V/cm. Our numerical results show that the band dispersions of a protein are large during the marching stage, but the dispersions are significantly reduced when the double peaks start to merge. This rearrangement of spreading band is very unique compared to linear electrokinetic phenomena (capillary electrophoresis, zone electrophoresis or electroosmosis) and is independent of channel position and channel shape. Hence, one can perform IEF in complex geometries without incorporating hyperturns.

On-chip cavity-enhanced absorption spectroscopy using a white light-emitting diode and polymer mirrors

Lab on a Chip ◽  
2015 ◽  
Vol 15 (3) ◽  
pp. 711-717 ◽  
Author(s):  
Cathy M. Rushworth ◽  
Gareth Jones ◽  
Martin Fischlechner ◽  
Emma Walton ◽  
Hywel Morgan
Keyword(s):  
Absorption Spectroscopy ◽  
White Light ◽  
Microfluidic Chip ◽  
Path Length ◽  
Light Emitting Diode ◽  
Absorption Path Length ◽  
Light Emitting ◽  
Enhanced Absorption ◽  
Cavity Enhanced Absorption Spectroscopy ◽  
On Chip

We have integrated disposable polymer mirrors within a microfluidic chip to form a multi-pass cell, which increases the absorption path length by a maximum of 28 times, providing micromolar detection limits in a probed volume of 10 nL.

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