Examination of laser microbeam cell lysis in a PDMS microfluidic channel using time-resolved imaging

Abstract

We use time-resolved imaging to examine the lysis dynamics of non-adherent BAF-3 cells within a microfluidic channel produced by the delivery of single highly-focused 540 ps duration laser pulses at λ = 532 nm. Time-resolved bright-field images reveal that the delivery of the pulsed laser microbeam results in the formation of a laser-induced plasma followed by shock wave emission and cavitation bubble formation. The confinement offered by the microfluidic channel constrains substantially the cavitation bubble expansion and results in significant deformation of the PDMS channel walls. To examine the cell lysis and dispersal of the cellular contents, we acquire timeresolved fluorescence images of the process in which the cells were loaded with a fluorescent dye. These fluorescence images reveal cell lysis to occur on the nanosecond to microsecond time scale by the plasma formation and cavitation bubble dynamics. Moreover, the time-resolved fluorescence images show that while the cellular contents are dispersed by the expansion of the laser-induced cavitation bubble, the flow associated with the bubble collapse subsequently re-localizes the cellular contents to a small region. This capacity of pulsed laser microbeam irradiation to achieve rapid cell lysis in microfluidic channels with minimal dilution of the cellular contents has important implications for their use in lab-on-a-chip applications.

A microscopic steam engine implemented in an optical tweezer

“…For example, optical pumps in microfluidic applications 24 , cell poration 21,22 and cell lysis 25 .…”

Shearing flow from transient bubble oscillations in narrow gaps

“…These bubbles can be generated with a focused laser pulse [1][2][3], acoustically excited capillary waves [4], or through spark discharges [5]. Applications of these transient pulsating flows span cell stretching [6,7], liquid pumping [8], switching and sorting [9,10], mixing [11], and droplet generation [12].…”

Microfluidic Platforms for Single-Cell Protein Analysis

“…78,79 Laser photolysis can rapidly lyse cells so that cells are frozen at the moment of photolysis. 37,80 For cellular proteins that cannot be amplified, efficient separation and sensitive detection are desired for identification and analysis. The separation modalities such as chromatography and electrophoresis within microchannels can be incorporated into the same chip to perform high-resolution analysis after efficient sample transfer.…”