Sensing Immobilized Molecules of Streptavidin on a Silicon Surface by Maldi-Tof Mass Spectrometry and Fluorescence Microscopy

Abstract

A hydrogen-terminated Si (111) surface was modified to form an aminoterminated monolayer for immobilization of streptavidin. Cleavage of an N-(ω-undecylenyl)-phthalimide covered surface using hidrazine yields an amino group-modified surface, which serves as a substrate for the attachment of biotin and subsequently streptavidin. We used surface analytical techniques to characterize the surface and to control the course of functionalization before the immobilization of streptavidin. To confirm the presence of the streptavidin Texas red on the surface two powerful techniques available in a standard biochemical laboratory are used, Fluorescence Microscopy and MALDI-TOF that allow us to detect and determine the immobilized streptavidin. This work provides an avenue for the development of devices in which the exquisite binding specificity of biomolecular recognition is directly coupled to a biosensor. In addition, we have demonstrated that MALDI-TOF and fluorescence microscopy are useful techniques for the characterization of silicon functionalized surfaces.

Strategies for the surface biofunctionalization of sulfur-based chalcogenide infrared optical glasses

“…On the other hand, small particles were observed in the substrates functionalized with Mal-EG 3 -biotin (RMS: 1.3 ± 0.2 nm), DBCO-EG 4 -biotin (RMS: 1.0 ± 0.3 nm) and, to a much lesser extent, on Mal-hydrazine-biotin (RMS: 0.89 ± 0.06 nm). The height range of these particles, 3-6 nm, corresponds to previously reported AFM measurements of Streptavidin 8,34 supporting ATR results regarding the presence of the protein on the functionalized surfaces. Finally, almost none of such particles were observed on the pristine substrate exposed to Streptavidin-Cy5, this possibly due to the effectiveness of Tween ® 20 in limiting non-specific adsorption.…”

Strategies for Chalcogenide Thin Film Functionalization

“…The literature, over the last 30 years, provided a number of AFM studies on STV-modified surfaces. 29 Some authors estimated the size of streptavidin interacting with biotin to be more elongated with dimensions of 3 × 10 nm 2 (CED of 13 nm), 34 others reported heights of 4.5 nm, 35 while full coverage with STV of porous biotinylated silicon was also reported. 17 These studies are in accordance with our results, indicating successful STV capture by our functionalized Ge−Se−Te substrates.…”