Liquid Mechanical Behavior of Mixed Monolayers of Amino and Alkyl Silanes by Atomic Force Microscopy

Abstract

The adsorption of mixed terminally aminated organosilyl compounds with long-chain n-alkyltrichlorosilanes on silica substrates has been studied by FTIR and AFM to deposit and study DNA. By optimization of deposition conditions, the mixed monolayers were found to be well organized and homogeneous. The amino group was protected to obtain a reproducible grafting and then deprotected after the film formation. In addition, atomic force microscopy (AFM) studies in both dynamical modes, amplitude modulation and frequency modulation, reveal that the layer behaves as a fluid as measured by the tip-cantilever and has a smaller characteristic time than the tip-cantilever. For three amplitudes, the experimental frequency shifts have been modeled for a fluidlike layer crossed by the tip. Finally, we show that this new fluidlike monolayer is suitable for DNA deposition and AFM studies.

Electrochemical Atomic Force Microscopy Using a Tip-Attached Redox Mediator for Topographic and Functional Imaging of Nanosystems

“…Moreover, since the tip solely comes in intermittent contact with the substrate, lateral frictional forces are minimized, which makes this technique ideally suited for imaging fragile biological species and very attractive as a basis for the microscopy we propose to develop. It is also worth noting that in situ tapping mode AFM has proved to be highly suitable for the structural characterization of molecular layers selfassembled onto surfaces 45,46 and was also used in a recent report for studying the compression of surfaceimmobilized PEG chains. 47 Upon mechanical excitation by a dithering piezo, the home-fabricated AFM-SECM probes gave rise to multiple resonance peaks at frequencies ranging from 1 to 10 kHz.…”

Multistep Anchoring Route of Luminescent (5‐Amino‐1,10‐phenanthroline)tris(dibenzoylmethane)europium(III) on Si(100)

“…The main bands at 2926-2927 and 2856-2857 cm -1 are assigned to the ν a (CH 2 ) and ν s (CH 2 ) stretching modes of the undecanoyl backbone, respectively. [26,27] Figure 2 (b) compares the carbonyl stretching of acid-Si and NHS-Si. A shift of the carbonyl stretching from 1721 (for acid-Si) to 1748 cm -1 (for NHS-Si) is evident, as expected for the ester formation.…”

Hybrid Organotin and Tin Oxide-based Thin Films Processed from Alkynylorganotins: Synthesis, Characterization, and Gas Sensing Properties.

“…The energies of the methylene vibrations are known to be a good probe of the conformation and the local organization of the alkyl chains. 69 In self-assembled alkyl monolayers, 70,71 these bands were thus found in the ranges of 2851−2849 and 2921−2917 cm −1 that was typical of fully extended all-trans alkyl chains. 72 As a consequence, the butylene linker within the TF 120 layer showed a close packing with a weak population of the gauche conformers.…”