An AFM determination of the effects on surface roughness caused by cleaning of fused silica and glass substrates in the process of optical biosensor preparation.
The covalent attachment of organic films and of biological molecules to fused silica and glass substrates is important for many applications. For applications such as biosensor development, it is desired that the immobilised molecules be assembled in a uniform layer on the surface so as to provide for reproducibility and speed of surface interactions. For optimal derivatisation the surface must be appropriately cleaned to remove contamination, to create surface attachment sites such as hydroxyl groups, and to control surface roughness. The irregularity of the surface can be significant in defining the integrity and density of immobilised films. Numerous cleaning methods exist for fused silica and glass substrates and these include gas plasmas, and combinations of acids, bases and organic solvents that are allowed to react at varying temperatures. For many years, we have used a well established method based on a combination of washing with basic peroxide followed by acidic peroxide to clean and hydroxylate the surface of fused silica and glass substrates before oligonucleotide immobilisation. Atomic force microscopy (AFM) has been used to evaluate the effect of cleaning on surface roughness for various fused silica and glass samples. The results indicate that surface roughness remains substantial after use of this common cleaning routine, and can provide a surface area that is more than 10% but less than 30% larger than anticipated from geometric considerations of a planar surface.
Henke
Lisa
L
Chemical Sensors Group, Department of Chemistry, University of Toronto at Mississauga, Erindale Campus, Room 4060, 3359 Mississauga Road North, Mississauga, Ont., L5L 1C6, Canada.
Nagy
Noemi
N
Krull
Ulrich J
UJ
D015374:Biosensing Techniques / Q000295:instrumentation / Q000379:methods; D005898:Glass / Q000737:chemistry*; D008422:Materials Testing / Q000295:instrumentation / Q000379:methods*; D018625:Microscopy, Atomic Force / Q000379:methods; D008962:Models, Theoretical; D055095:Optics and Photonics / Q000295:instrumentation; D010545:Peroxides / Q000737:chemistry*; D011786:Quality Control; D012680:Sensitivity and Specificity; D012822:Silicon Dioxide / Q000737:chemistry*; D013499:Surface Properties
D010545:Peroxides; D012822:Silicon Dioxide