Gregory Jon Sommer

Microfluidic digital isoelectric fractionation for rapid multidimensional glycoprotein analysis.

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.

Lab-on-a-disk immunoassay for ocular diagnostics

Monitoring of angiogenic cytokines in the eyes of patients with diabetic retinopathy (DR) and age-related macular degeneration (AMD) is crucial to confirm efficacy of treatment. We present a novel “lab-on-a-disk” immunoassay for monitoring vascular endothelial growth factor in the eye with potential for deployment at the ophthalmologists office as a point-of-care diagnostic. Using rudimentary sedimentation principles, the immunoassay can be completed in a two-step method within 16-18 minutes. The platform is comparable in sensitivity to conventional ELISA. Adoption of this platform at the point-of-care will facilitate accurate dosing of anti-angiogenic medication used to treat DR and AMD as well as identify non-responders.