We demonstrate a simple method for coupling alkynes to alkynes. The method involves tandem azide-alkyne cycloaddition reactions ("click" chemistry) for the immobilization of 1-alkyne species onto an alkyne modified surface in a one-pot procedure. In the case presented, these reactions take place on a nonoxidized Si(100) surface although the approach is general for linking alkynes to alkynes. The applicability of the method in the preparation of electrically well-behaved functionalized surfaces is demonstrated by coupling an alkyne-tagged ferrocene species onto alkyne-terminated Si(100) surfaces. The utility of the approach in biotechnology is shown by constructing a DNA sensing interface by derivatization of the acetylenyl surface with commercially available alkyne-tagged oligonucleotides. Cyclic voltametry, electrochemical impedance spectroscopy, X-ray photoelectron spectroscopy, and X-ray reflectometry are used to characterize the coupling reactions and performance of the final modified surfaces. These data show that this synthetic protocol gives chemically well-defined, electronically well-behaved, and robust (bio)functionalized monolayers on silicon semiconducting surfaces.

Two different interfaces prepared via UV-hydrosilylation of undecylenic acid and 1,8-nonadiyne on silicon(111) have been explored to develop a robust electrochemical DNA sensor. Electrodes modified with undecylenic acid were found to stably immobilise DNA but could not resist the growth of insulating oxides, whereas 1,8-nonadiyne modified electrodes satisfy both requirements.

Electrochemical impedance spectroscopy was used to differentiate between different target DNA sequences without the use of a redox label or application of large bias voltages. This method relies on the formation of a mixed self-assembled monolayer (SAMs) composed of single-stranded DNA and a diluent, mercaptoethanol. Recognition of the DNA analytes was achieved through the significant increase in conductance for the double stranded DNA, as compared to single-stranded DNA. Non-complementary and single base-pair mismatches were also able to be differentiated. 2010 IEEE.

Dedicated to Prof.D r. Wolfgang Schuhmann on the occasiono fh is 60 th birthday type silicon, i.e.h oles.T his effecti senhanced by the formation of double-stranded (ds)DNA molecules and hence is the premise to label-free detectiono ft he DNA hybridization.O verall, our studies provide apromising alternative to design ab iosensor to detect the hybridization of DNAm oleculeso nthesilicon surface.