(13d) Development Of Semi-Conductor Biomaterials For Regulating Cell Growth

Surfaces and interfaces play a very important role in biomaterials and medicine since most biological reactions occur here. Investigating cellular response to biomaterials is of great interest, particularly the interaction with biomaterials that incorporate stimulatory cues, such as electric signals, to regulate cell functions. Such biomaterials could also be engineered to respond to cellular behavior, thus being potentially applicable as diagnostic sensors. It has been demonstrated that osteoblasts (bone-forming cells) respond to electrical stimulation and surface energy.

It was shown recently that thickness has a strong effect on the surface energy of poly(3-octylthiophene-2,5-diyl) (P3OT), a semiconductor in its undoped state. With this in mind, the overall objective of this research was to determine the effect of P3OT thickness on attachment and proliferation of osteoblasts. For rapid screening, we developed thickness gradient libraries (120 ? 200 nm) of P3OT for regulating proliferation in osteoblasts. We demonstrate that P3OT thickness has an effect on MC3T3-E1 cell proliferation. Higher proliferation is observed between 120 - 130 nm for cells cultured for a period of one day. The proliferation ratio is significantly higher on P3OT after one day compared to tissue culture polystyrene controls. We also demonstrate that cell attachment after a period of 4 hours is not affected by changes in thickness over the low range: P3OT thicknesses (10 ? 60 nm). However, cell circularity and area are significantly higher for cells cultured on bare silicon wafers when compared to cells cultured on P3OT thin films. This suggests that surface chemistry has an effect on osteoblast attachment and that a film as thin as 10nm is sufficient to screen the silicon chemistry and VDW forces.

We intend to investigate attachment at the higher thickness range (120 ? 200 nm) and proliferation at the lower thickness range (10 ? 60 nm) to determine if there is a correlation between functions. We also intend to study other functions such as protein expression and mineralization.