High-Resolution X-ray Photoelectron Spectroscopy of Mixed Silane Monolayers for DNA Attachment

Abstract

The amine density of 3-aminopropyldimethylethoxysilane (APDMES) films on silica is controlled to determine its effect on DNA probe density and subsequent DNA hybridization. The amine density is tailored by controlling the surface reaction time of (1) APDMES, or (2) n-propyldimethylchlorosilane (PDMCS, which is not amine terminated) and then reacting it with APDMES to form a mixed monolayer. High-resolution X-ray photoelectron spectroscopy (XPS) is used to quantify silane surface coverage of both pure and mixed monolayers on silica; the XPS data demonstrate control of amine density in both pure APDMES and PDMCS/APDMES mixed monolayers. A linear correlation between the atomic concentration of N atoms from the amine and Si atoms from the APDMES in pure APDMES films allows us to calculate the PDMCS/APDMES ratio in the mixed monolayers. Fluorescence from attached DNA probes and from hybridized DNA decreases as the percentage of APDMES in the mixed monolayer is decreased by dilution with PDMCS.

Study on the use of 3‐aminopropyltriethoxysilane and 3‐chloropropyltriethoxysilane to surface biochemical modification of a novel low elastic modulus Ti–Nb–Hf alloy

“…Samples were bombarded with a pulsed Bismuth liquid metal ion source (Bi 3+ ), at energy of 25 keV. The gun was operated with a 20 ns pulse width, 0.3 pA pulsed ion current for a dosage lower than 5x10 11 ions/cm 2 , well below the threshold level of 1x10 13 ions/cm 2 generally accepted for static SIMS conditions…”

“…This problem can be overcome, at least in part, by adding a preliminary activation treatment. For pure titanium, there is a large diversity of examples in the literature suggesting different activation methods to provide reactive groups for covalent immobilization of biomolecules (mainly -OH groups) [2][3][4][5][6][7][8][9][10][11] and organosilanes bearing different functional groups [12][13][14][15][16][17]. Recently, a comparative study between two activation methods frequently used (Oxygen plasma and Piranha solution) was performed by V. Paredes [18].…”

“…Nowadays, organosilane precursors bearing functional groups such as amino [12][13][14][15][16][17][18][19][20][21][22], thiol, carboxyl, phosphate, vinyl [23][24][25], cyanide [26], phenyl [24,27] or sulphhydryl groups are readily available. Despite the wide variety of silane precursors available for surface modification, the majority of studies have employed aminosilanes, in particular 3-aminopropyltriethoxysilane (APTES) [11][12][13][14][15][16][17][18][19][20][21][22]. Nevertheless, the 3-chloropropyltriethoxysilane (CPTES) is also proposed by other authors [2,4,10].…”

Synthesis of novel nucleobase-terminated organosilane and its self-assembly on a substrate

“…Thus, surface functionalizations by the self-assembly of organosilanes have been used to construct bioconjugated devices, such as biosensors and bioseparators. 18,19,22,23 In the standard methods for preparing bioconjugated devices based on the self-assembly of organosilanes, after organosilanes with a functional group such as carboxyl and amino groups are self-assembled on hydroxylated surfaces, biomolecules are covalently attached to the functional groups on the modified surfaces. Thus, in these methods, the preparation of biomolecule-attached surfaces requires several processes.…”

“…For example, thiol-modified DNA oligomers were covalently attached to SAMs formed from organosilanes with a functional group. 18,19 Standard methods for fabricating SAMs and multilayers of nucleic acids and nucleobases require several steps. First, an appropriate substrate is immersed into a solution containing active molecules with a head group for attaching to a substrate and a functional group for binding to nucleic acids and a nucleobase.…”