title: Introducing cymantrene labels into scattering scanning near-field infrared microscopy.
abstract: In this paper we investigate metal-organic compounds as infrared (IR) active labels by scattering scanning near-field infrared microscopy (IR s-SNOM, often also abbreviated as s-SNIM) with a lateral resolution of 90 × 90 nm(2). Tailor-made IR spectroscopic probes based on cymantrene (CpMn(CO)(3) with Cp = η(5)-C(5)H(5)) conjugated to a cysteine-modified pseudoneurotensin (pNT-Cys-OH) peptide were prepared by automated microwave-assisted solid phase peptide synthesis (SPPS) and characterized by HPLC, ESI-MS and IR. Well-defined patterned self-assembled monolayers on a gold surface were prepared by microcontact printing of 1-octadecanethiol (ODT) followed by additional incubation in ethanolic solution of the cymantrene-peptide derivative. The self-assembled monolayers have been evidenced by infrared reflection absorption spectroscopy (IRRAS) and AFM. CO laser source radiation was tuned (1944, 1900, 1798 and 1658 cm(-1)) for imaging contrast with good matching correlation between spectroscopic and topographic patterns at specific characteristic metal carbonyl and amide bands (1944 cm(-1) (λ = 5.14 μm) and 1658 cm(-1) (λ = 6.03 μm)). Cymantrene probes provide an attractive method to tag a unique spectroscopic feature on any bio(macro)molecule. Introducing such probes into super-resolution IR s-SNOM will enable molecular tracking and distribution studies even in complex biological systems.
authors.affiliation: Physical Chemistry II, Ruhr-University Bochum, Bochum, Germany. Ilona.Kopf@rub.de
authors.forename: Ilona
authors.initials: I
authors.lastname: Kopf
authors.forename: Harmel W Peindy
authors.initials: HW
authors.lastname: N'Dongo
authors.forename: Fouad
authors.initials: F
authors.lastname: Ballout
authors.forename: Ulrich
authors.initials: U
authors.lastname: Schatzschneider
authors.forename: Erik
authors.initials: E
authors.lastname: Bründermann
authors.forename: Martina
authors.initials: M
authors.lastname: Havenith
mesh_terms: D000595:Amino Acid Sequence; D007259:Infrared Rays; D008853:Microscopy / Q000379:methods*; D009842:Oligopeptides / Q000737:chemistry; D009942:Organometallic Compounds / Q000737:chemistry*
chemical_list: D009842:Oligopeptides; D009942:Organometallic Compounds; C044679:manganese cyclopentadienyl tricarbonyl