Multimarker Cellular Screening Using Variable Cross-Section Pores

Multimarker Cellular Screening Using Variable Cross-Section Pores

 

Karthik Balakrishnan,^a Trong Nguyen^b, and Lydia Sohn^a*

a, Dept. of Mech. Engineering, Univ. of California, Berkeley, CA, 94720, United States.

b, Dept. of Engineering Physics, Univ. of California, Berkeley, CA, 94720, United States.

 

 

 

Multimarker screening is a useful tool for disease diagnosis, as cell characterization is essential for understanding and dealing with pathologic conditions.  Existing techniques suffer from drawbacks as they require advanced preparation, including labeling cells, which increases time for incubation steps and can change cellular properties.  This presents issues if cells are to be used for post-screening analysis.  Microfluidic pores have emerged as versatile tools capable of probing the properties of proteins and nucleic acids.^1,2 Recent work^3,4 has shown that pore functionalization can result in slower translocation rates of a particle due to particle-pore interactions, thereby providing chemical specificity for detection of single molecules and cells.  Because functionalization with only one type of organic species limits the effectiveness of these pores, we have developed a novel pore device that can characterize multiple surface markers of a cell in a single measurement.

Our novel device utilizes standard photolithography to define a single pore into variable cross-section regions.  Individual transit times within the pore are easily extracted, providing a means to determine transient binding events within each region of the pore.⁵  By functionalizing different regions of the pore with different antibodies and by comparing transit times with controls, we are able to determine the presence of different markers on the surface of a cell in a single measurement.  Our screening method is label-free, as the labels (i.e. antibodies) are incorporated in the device directly. Furthermore, our variable cross-section pores can be used to create unique electronic signatures that can improve real-time analysis capabilities. 

References

1. H. Baley, Current Opinion in Chemical Biology, 2006, 10, 628-637.

2.  J. J. Kasianowicz, E. Brandin, D. Branton, D. W. Deamer, Proc. Natl. Acad. Sci., 1996, 93, 13770-13773.

3. M. Wanunu and A. Meller, Nano Letters, 2007, 7, 1580-1585.

4.  A. Carbonaro, S. K. Mohanty, H. Huang, L.A. Godley, L. L. Sohn, Lab Chip, 2008, 8, 1478-1785.

5.  K. Balakrishnan, T. Nguyen, G. Anwar, M. Chapman, A. Kesavaraju, L. L. Sohn, in preparation.