Evaluation of Chemical Interactions between Small Molecules in the Gas Phase Using Chemical Force Microscopy
Jieun Lee,
Soomi Ju,
In Tae Kim,
Sun-Hwa Jung,
Sun-Joon Min,
Chulki Kim,
Sang Jun Sim,
Sang Kyung Kim
Affiliations
Jieun Lee
Center for Biomicrosystems, Korea Institute of Science and Technology (KIST), Hwarangno 14-gil 5, Seongbuk-gu, Seoul 136-791, Korea
Soomi Ju
Center for Biomicrosystems, Korea Institute of Science and Technology (KIST), Hwarangno 14-gil 5, Seongbuk-gu, Seoul 136-791, Korea
In Tae Kim
Center for Biomicrosystems, Korea Institute of Science and Technology (KIST), Hwarangno 14-gil 5, Seongbuk-gu, Seoul 136-791, Korea
Sun-Hwa Jung
Center for Neuro-Medicine, Brain Science Institute, Korea Institute of Science and Technology(KIST), Hwarangno 14-gil 5, Seongbuk-gu, Seoul 136-791, Korea
Sun-Joon Min
Department of Applied Chemistry, Hanyang University, Sangnok-gu, Ansan, Gyeonggi-do 15588, Korea
Chulki Kim
Center for Sensor System Research, Korea Institute of Science and Technology (KIST), Hwarangno 14-gil 5, Seongbuk-gu, Seoul 136-791, Korea
Sang Jun Sim
Department of Chemical and Biological Engineering, Korea University, 5-ga Annam-dong, Seongbuk-gu, Seoul 136-713, Korea
Sang Kyung Kim
Center for Biomicrosystems, Korea Institute of Science and Technology (KIST), Hwarangno 14-gil 5, Seongbuk-gu, Seoul 136-791, Korea
Chemical force microscopy analyzes the interactions between various chemical/biochemical moieties in situ. In this work we examined force-distance curves and lateral force to measure the interaction between modified AFM tips and differently functionalized molecular monolayers. Especially for the measurements in gas phase, we investigated the effect of humidity on the analysis of force-distance curves and the images in lateral force mode. Flat chemical patterns composed of different functional groups were made through micro-contact printing and lateral force mode provided more resolved analysis of the chemical patterns. From the images of 1-octadecanethiol/11-mercapto-1-undecanoic acid patterns, the amine group functionalized tip brought out higher contrast of the patterns than an intact silicon nitride tip owing to the additional chemical interaction between carboxyl and amine groups. For more complex chemical interactions, relative chemical affinities toward specific peptides were assessed on the pattern of 1-octadecanethiol/phenyl-terminated alkanethiol. The lateral image of chemical force microscopy reflected specific preference of a peptide to phenyl group as well as the hydrophobic interaction.
