Surface imaging was obtained in non-contact mode using silicon/aluminium-coated cantilevers (PPP-NCHR 10 M, Park Systems, Suwon, South Korea) 125 mm long with a resonance frequency of 200 to 400 kHz and nominal force constant of 42 N/m. The scan frequency was typically 1 Hz per line. The scan area in surface analysis was 1 μm × 1 μm. Spectroscopic reflectometry click here Reflectivity spectra of PSi optical structures

were obtained by a simple experimental setup: a white light was sent on PSi samples through a Y optical fibre (Avantes, Apeldoorn, The Netherlands). The same fibre was used to guide the output signal to an optical spectrum analyser (Ando AQ6315A, Tokyo, Japan). The spectra were acquired at normal incidence over the range 600 to 1,200 nm with a resolution of 5 nm. The reflectivity spectra shown in the graphs are the average of

three measurements for each sample. High-performance liquid chromatography The purification and control of the synthesized ONs was carried out using a Jasco PU2089 PLUS HPLC system (Easton, MD, USA) equipped with an anion exchange column (1000-8/46, 4.4 × 50 mm, 5 μm, Macherey-Nagel, Düren, Germany) using selleck chemical a linear gradient from 0% to 100% B in 30 min, flow rate = 1 mL/min and detection at 260 nm (buffer A: 20 mM NaH2PO4 aq. solution, pH 7.0, containing 20% (v/v) CH3CN; buffer B: 20 mM NaH2PO4 aq. solution, pH 7.0, containing 1 M NaCl and 20% (v/v) CH3CN). Results and discussion In our previous work [16], we investigated the passivation ability of oxidized PSi multilayered structures by two aminosilane compounds

(APTES and APDMES) used for the in situ synthesis of a 13-mer the polythymine ON strand. We successfully demonstrated that even using the less aggressive carbonate/methanol solution as the ON deprotection system, hybridization with the complementary ON target took place, thus confirming that ONs can be synthesized and deprotected on the PSi surface. However, the synthesis of mixed-sequence ONs using the carbonate/methanol solution in the final ON deprotection step would require the use of highly expensive AP26113 research buy ultra-mild nucleobase-protected phosphoramidites characterized by having non-standard very labile protecting groups. In the present paper, we describe the results of alternative PSi-friendly ON deprotection conditions during the in situ synthesis of mixed-sequence ONs on PSi supports by using standard phosphoramidite nucleoside monomers, without using ultra-mild reagents. Measurement of optical spectra by spectroscopic reflectometry is very useful since both the position of resonance wavelength and the shape of lateral fringes give quantitative information about PSi corrosion or stability: the peak wavelengths of each PSi-Ma-h microcavity before and after silanization are reported in Table 2.