Biocompatibility of atomic layer-deposited alumina thin films

Presented in this paper is a study of the biocompatibility of an atomic layer-deposited (ALD) alumina (Al2O3) thin film and in ALD hydrophobic coating oil standard glass cover slips, The pure ALD alumina coating exhibited, a water contact angle of 55' +/- 5 degrees attributed, in part, to a high concentration of -OH group on the surface. In contrast, the hydrophobic coating (tridecafluoro-1,1,2,2-tetrahydro-octyl-methyl-bis(dimethylamino)silane)1 had a water contact amble of 108 degrees +/- 2 degrees. Observations using differential interference contrast microscopy on human coronary artery smooth muscle Cells showed normal cell proliferation on both the ALD alumina and hydrophobic coatings when compared to cells grown on control substrates. These observations sugested good biocompatibility over a period of 7 days in vitro. Using a colorimetric assay technique to assess cell viability, the cellular response between the three substrates can be differentiated to show that the ALD alumina coating is more biocompatible and that the hydrophobic coating is less biocompatible when compared to the control. These results suggest that patterning a substrate with hydrophilic and hydrophobic groups can control cell growth. This patterning can further enhance the known advantages of ALD alumina, such as conformality and excellent dielectric properties for bio- micro electro mechanical systems (Bio-MEMS) in sensors, actuators, and microfluidics devices. (C) 2007 Wiley Periodicals, Inc.