Transcript Document

Force Microscopy of
Nonadherent Cells:
A Comparison of Leukemia
Cell Deformability
by Rosenbluth, Lam & Fletcher
Sangjin Ryu
Department of Mechanical Engineering
Background
Better knowledge of mechanical property
changes in leukemia cells
→ Improved understanding of leukemia
 Atomic force microscopy (AFM) to
measure the stiffness of cells
→ Lab module 2: Elastic modulus
 Nonadhesive cells tend to slip from the
cantilever tip under an applied load

How to Fix Leukemia Cells?
Sticky surface
 Trapping within Millipore filters
 Micropipette aspiration
 Microfabricated well

Rosenbuth, Lam & Fletcher 2006 Biophys. J.
Experiments

Cells for investigation
 Acute
myeloid leukemia cell: HL60 cell
 Acute lymphoid leukemia cell: Jurkat cell
 Normal leukocyte: Human neutrophil

Tips for investigation
 Pyramid
AFM tip
 Sphere indenter
Mechanical Models

Hertzian model: Elastic modulus

2
4
F
1


2 
3E tan 


Liquid droplet model: Membrane tension
8TS 2  1 cos  


d 

k  Rc
S 
Results

Hertzian model is better

Stiffness: HL60>Jurkat>Neutrophil