Three-dimensional optical force field on a Chinese hamster ovary cell in a fiber-optical dual-beam trap

We used a fiber-optical dual-beam trap (single-mode fiber, lambda = 532nm, trapping power ~ 22mW, the distance between the two fiber end-faces = 125mum) to capture a Chinese hamster ovary (CHO) cell with a diameter of approximately 15mum and tracked its three-dimensional Brownian motion via a pair of orthogonal quadrant photodiodes. By analyzing the Brownian motion of the trapped CHO cell, we determined the force constants of the optical force field on the CHO cell to be k(x)=6.75 pN/mum, k(y)=5.53 pN/mum, k(z)=1.96 pN/mum, and k(x)=2.91 pN/mum, k(y)=2.7 pN/mum, k(z)=0.79 pN/mum, respectively, before and after the CHO cell was treated with latrunculin, a toxic drug known to disrupt the cytoskeleton of the cell.