Development of poly(3-octylthiophene) thin films for regulating osteoblast growth

The investigation of electrically conducting polymers (CPs) for use in biomedical applications has expanded greatly since the discovery in the 1980s that these materials are compatible with many biological molecules. CPs are able, via electrical stimulation, to modulate the behavior of certain electrically responsive cells (i.e., nerve, muscle, bone, and cardiac cells). CPs such as polypyrrole, polyaniline, and polythiophene have a conjugated structure that upon doping allows interchain hopping of electrons. In addition, most CPs have numerous attractive properties for biomedical applications, including the ability to transfer charges, to entrap and release biological molecules, and the potential to vary their chemical, electrical, and physical properties. Even though there has been significant progress, many biomedical issues remain unexplored, especially the interaction between different cell types (e.g., neurons, fibroblasts, and osteoblasts) and substituted polythiophenes (PTs) in both the undoped and doped states. PTs are one of the most widely studied CPs, therefore ample knowledge exists on their chemical, electrical, and physical properties. They also have great potential for biomedical applications as they have been used as biosensors, molecular actuators, and cell support substrates.;The overall objective of this work is to assess the suitability of poly(3-octylthiophene) (P3OT) to sustain MC3T3-E1 osteoblast attachment and growth. The central hypothesis is that specific P3OT film properties (e.g., thickness, film preparation conditions, and level of doping) are able to regulate osteoblast functions (e.g., attachment and proliferation). Discrete and combinatorial techniques were utilized in this work to prepare and characterize thin films of P3OT, a semiconductor in its undoped state, and to study its interaction with MC3T3-E1 osteoblasts. The MC3T3-E1 cell line was chosen because it is well understood, is known to exhibit a developmental sequence analogous to osteoblasts in bone tissue, and because of previous success in regulating proliferation and attachment using conducting substrates.;In this work we demonstrate that P3OT is a suitable surface to sustain MC3T3-E1 attachment and proliferation with no observed cytotoxicity. We show that P3OT has an effect on MC3T3-E1 attachment and proliferation as area, circularity, and proliferation ratio are significantly different for P3OT compared to control surfaces. We also demonstrate that P3OT doping and film preparation conditions have an effect on osteoblast attachment and proliferation but that thickness over a low and high range does not affect osteoblast functions.;This work is significant because it contributes to the growing area of conducting polymers in biomedical applications and establishes P3OT as a potential cell substrate that sustains MC3T3-E1 attachment and promotes high levels of cell proliferation.