title: Single cell isolation process with laser induced forward transfer.
abstract: BACKGROUND
  A viable single cell is crucial for studies of single cell biology. In this paper, laser-induced forward transfer (LIFT) was used to isolate individual cell with a closed chamber designed to avoid contamination and maintain humidity. Hela cells were used to study the impact of laser pulse energy, laser spot size, sacrificed layer thickness and working distance. The size distribution, number and proliferation ratio of separated cells were statistically evaluated. Glycerol was used to increase the viscosity of the medium and alginate were introduced to soften the landing process.
  
  
  RESULTS
  The role of laser pulse energy, the spot size and the thickness of titanium in energy absorption in LIFT process was theoretically analyzed with Lambert-Beer and a thermal conductive model. After comprehensive analysis, mechanical damage was found to be the dominant factor affecting the size and proliferation ratio of the isolated cells. An orthogonal experiment was conducted, and the optimal conditions were determined as: laser pulse energy, 9 μJ; spot size, 60 μm; thickness of titanium, 12 nm; working distance, 700 μm;, glycerol, 2% and alginate depth, greater than 1 μm. With these conditions, along with continuous incubation, a single cell could be transferred by the LIFT with one shot, with limited effect on cell size and viability.
  
  
  CONCLUSIONS
  LIFT conducted in a closed chamber under optimized condition is a promising method for reliably isolating single cells.
authors.affiliation: School of Electromechanical Engineering, Guangdong University of Technology, Guangzhou, 510006 China ; Microsystems Laboratory, STI-LMIS, Ecole Polytechnique Federale de Lausanne, CH-1015 Lausanne, Switzerland ; Guangdong Provincial Key Laboratory of Functional Soft Condensed Matter, Guangzhou, 510006 China.
authors.forename: Yu
authors.initials: Y
authors.lastname: Deng
authors.affiliation: Microsystems Laboratory, STI-LMIS, Ecole Polytechnique Federale de Lausanne, CH-1015 Lausanne, Switzerland.
authors.forename: Philippe
authors.initials: P
authors.lastname: Renaud
authors.affiliation: School of Electromechanical Engineering, Guangdong University of Technology, Guangzhou, 510006 China.
authors.forename: Zhongning
authors.initials: Z
authors.lastname: Guo
authors.affiliation: School of Electromechanical Engineering, Guangdong University of Technology, Guangzhou, 510006 China.
authors.forename: Zhigang
authors.initials: Z
authors.lastname: Huang
authors.affiliation: Guangdong Provincial Key Laboratory of Functional Soft Condensed Matter, Guangzhou, 510006 China.
authors.forename: Ying
authors.initials: Y
authors.lastname: Chen
keywords: Cell damage; Laser induced forward transfer; Mechanical stress; Proliferation; Single cell isolation