Date of Award:

5-2015

Document Type:

Thesis

Degree Name:

Master of Science (MS)

Department:

Biological and Irrigation Engineering

Advisor/Chair:

Anhong Zhou

Abstract

In this thesis the effect of mechanical stimuli on A549 lung cancer cells is studied. Modifications of polydimethylsiloxane (PDMS) surfaces are employed to alter the mechanical stimuli applied to the cells. Flat substrates are first studied and then micropillared substrates are designed, fabricated, and tested as a method to alter the mechanical properties of the PDMS surfaces.

Molds with micro-pillars are designed then fabricated from silicon using deep reactive ion etching. From these molds, a negative then a positive replicate is made using PDMS. The pillared PDMS substrates are fabricated in 10 geometries and used for experiments. A549 cells are cultured on these surfaces then analyzed using fluorescence microscopy and atomic force microscopy (AFM). Fluorescence microscopy images processed by ImageJ software measure the cell spreading area (m2) while AFM quantifies the cell stiffness (kPa).

For flat substrates, the cell stiffness and spreading area increase with increasing substrate stiffness. Further, results on pillared substrates show a similar trend based on pillar geometry changes. For pillared substrates, the A549 cell stiffness and spreading area increase as the height decreases, yet there is decreased cell stiffness and spreading area as the diameter and spacing decreases. The experiments show that changes in surface properties and only mechanical stimuli alter cellular morphology and biomechanics

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