The development of the next generation of medical implants involves attaching appropriate biorecognition molecules in the proper orientation and concentration on the surface of an implant, to prevent the cellular activation that leads to the foreign body response and implant encapsulation. Porphyrin molecules are ideal for the development of a uniform monolayer, with controlled, optimal spacing of biorecognition groups. Self-assembled porphyrin monolayers on gold surfaces with three custom synthesized alkylthiol substituted tetraphenylporphyrin molecules have been developed by our group. Several techniques including x-ray photoelectron spectroscopy (XPS), ultraviolet/visible absorption spectroscopy (UV/Vis), scanning tunneling microscopy (STM), and grazing-angle infrared spectroscopy (GAIR) are being used to characterize the monolayers. XPS and GAIR studies to date reveal that the porphyrins are chemisorbed to the surface through a sulfur-gold bond, and that the po rphyrin m olecules are aligned on the gold surface in a side-by-side orientation. GAIR results using a polarized light source indicate that the porphyrin rings are oriented parallel to the gold surface.
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