Microfluidic Digital Isoelectric
Fractionation for
Rapid Multidimensional Glycoprotein Analysis
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Abstract
Here we present an integrated microfluidic device for
rapid and
automated isolation and quantification of glycoprotein biomarkers
directly from biological samples on a multidimensional analysis platform.
In the first dimension, digital isoelectric fractionation (dIEF) uses
discrete pH-specific membranes to separate proteins and their isoforms
into precise bins in a highly flexible spatial arrangement on-chip.
dIEF provides high sample preconcentration factors followed by immediate
high-fidelity transfer of fractions for downstream analysis. We successfully
fractionate isoforms of two potential glycoprotein cancer markers,
fetuin and prostate-specific antigen (PSA), with 10 min run time,
and results are compared qualitatively and quantitatively to conventional
slab gel IEF. In the second dimension, functionalized monolithic columns
are used to capture and detect targeted analytes from each fraction.
We demonstrate rapid two-dimensional fractionation, immunocapture,
and detection of C-reactive protein (CRP) spiked in human serum. This
rapid, flexible, and automated approach is well-suited for glycoprotein
biomarker research and verification studies and represents a practical
avenue for glycoprotein isoform-based diagnostic testing