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One of the most exciting applications of porous silicon is that of a sensing material for a whole range of different analyte classes (bio- and chemical sensing). While initially the photoluminescence emission was used as the transduction event, new approaches exploiting other properties of the nanocrystalline architecture of the material are especially promising, such as electrochemical strategy (potentiometric and capacitance). Advances in techniques of chemical functionalization of porous silicon have increased the material stability and introduced new ways of organic molecules grafting to silicon via stable and covalent bonds. Hydride terminated porous silicon surfaces are reactive enough to allow for a wide range of chemistry, thus a variety of functional groups can be anchored to the surface upon demand. On the other hand, amino acids are known to be usable as recognition elements for electrochemical metal ion sensing. In this work, we report a three-step route to Glycine and Glycine ester grafting onto the porous silicon surface. The first step consists in thermal hydrosilylation of undecylenic acid with hydrogen terminated porous silicon surface at 150°C. It yields an organic monolayer covalently attached to the surface through Si-C bonds. The reaction takes place at the terminal C=C double bond of the molecule and the acid terminal groups remain intact. In the second step, the carboxylic-acid terminated monolayer was transformed to a succinimidyl ester. This activation was achieved using N-hydroxysuccinimide (NHS) and N-ethyl-N’-(3-dimethylaminopropyl)carbodiimide (EDC) as a coupling reagent. Finally, the amino acid was attached to the monolayer, by reacting with the activated ester. The reaction efficiency at each stage of the functionalization was confirmed using FTIR measurements. SIMS depth profiling showed a consistent level of carbon incorporation throughout the porous silicon. Electrochemical behaviour of the Glycine modified porous silicon in the presence of copper ions was studied by means of cyclic voltammetry measurements. |