Analytical Sciences, Talk
Microscale probing and patterning of biological surfaces using nested hydrodynamic flow confinement and recirculation of sub-microliter volumes of liquid
Govind Kaigala1, Julien Autebert1, Julien Cors1, Aditya Kashyap1, Robert Lovchik1, Emmanuel Delamarche1
1IBM Research GmbH
Microscale probing and patterning of biological surfaces plays a significant role in fields ranging from stimulation of adherent cells, microperfusion of brain slices, engineering cellular architectures, modulating stem-cell microenvironments to dispensing chemicals on cells for pharmacology studies [1]. In view of such applications, we developed the microfluidic probe (MFP), which is a non-contact, scanning microfluidic technology to directly operate on microscope slides and Petri dishes without the need for sealed channels/chambers [2]. The MFP is based on the hydrodynamic flow confinement (HFC) of nanoliter volumes of liquids over tens of micrometers of a surface. To exploit the opportunities of HFC, we recently developed nested HFC, wherein multiple layers of liquids are shaped to interact with a surface [3]. In the classical HFC, the asymmetry of injection to aspiration flow rates between two apertures is responsible for the dilution of the liquid of interest (processing liquid) by the immersion liquid, Fig. a. In the nested HFC, we use two extra apertures to “nest” the processing liquid inside a shaping liquid, Fig. b. We illustrated the use of nested HFC by efficiently patterning multiple antibodies on a surface simultaneously, with 5 μm resolution and a 100-fold decrease of reagent consumption compared to microcontact printing, Fig c. Nested HFC not only minimizes the usage of chemicals but also permits efficient retrieval of analytes from a surface, as demonstrated by the minimal dilution (below 2%) of the processing liquid in the inner flow confinement, Fig. d.
We are now developing a strategy to repeatedly use and circulate a defined volume of processing liquid within the MFP head. Combining nested HFC with liquid recirculation allows investigating two critical aspects of microscale surface biochemistry: (a) the efficient removal of analyte, and (b) efficient usage of chemicals on surfaces. In the presentation, we will outline how this new method will allow for new opportunities in microscale surface biochemistry and analytical sciences.
[1] A. Ainla, E. T. Jansson, N. Stepanyants, O. Orwar and A. Jesorka, Anal. Chem., 2010, 82 (11), 4529–4536.
[2] G. V. Kaigala, R. D. Lovchik and E. Delamarche, Angewandte Chemie, 2012, 45, 11224-11240.
[3] J. Autebert, A. Kashyap, R. D. Lovchik, E. Delamarche and G. V. Kaigala, Langmuir, 2014, 30(12), 3640-3645.