No abstract

Chemical derivatization of peptides allows efficient F2 laser single photon ionization (SPI) of Fmoc-derivatized peptides covalently bound to surfaces. Laser desorption photoionization mass spectrometry using 337-nm pulses for desorption and 157.6-nm pulses for threshold SPI forms large ions identified as common peptide fragments bound to either Fmoc or the surface linker. Electronic structure calculations indicate the Fmoc label is behaving as an ionization tag for the entire peptide, lowering the ionization potential of the complex below the 7.87-eV photon energy. This method should allow detection of many molecular species covalently or electrostatically bound to surfaces.

Mechanical load and stress are exerted upon heart muscle tissue in vivo, leading to changes in cellular biochemistry and physiology. Understanding the fundamental mechanisms of mechanical transduction at the cellular level requires the development of physiologically relevant models of cells in vitro. Silicone elastomers are widely used as flexible cell culture substrates for in‐vitro cardiac mechano‐biological studies. We describe here the use of peptide binding to and microfabrication of silicone elastomer membranes. We utilize these chemically and morphologically modified silicone membranes as improved flexible cell culture substrates in studies of cardiac mechano‐biology. We also discuss advances in surface modification and microfabrication that promise further development of improved heart cell cultures.

Long period x-ray standing wave fluorescence (XSW) and x-ray reflectivity techniques are employed to probe the conformation of a Br-polyethylene glycol (PEG)-peptide adsorbate at the hydrated interface of a polystyrene substrate. The Br atom on this Br-PEG-peptide construct serves as a marker atom allowing determination by XSW of its position and distribution with respect to the adsorption surface with angstrom resolution. Adsorption occurs on native or ion beam modified polystyrene films that are spin coated onto a Si substrate and display either nonpolar or polar surfaces, respectively. A compact, oriented monolayer of Br-PEG-peptide can be formed with the peptide end adsorbed onto the polar surface and the PEG end terminating with the Br tag extending into the aqueous phase. The 108 -141 Å distance of the Br atom from the polystyrene surface in this oriented monolayer is similar to the estimated ~150 Å length of the extended Br-PEG-peptide. This Brpolystyrene distance depends upon adsorption time and surface properties prior to adsorption. Incomplete multilayers form on the polar surface after sufficient adsorption time elapses. By contrast, adsorption onto the nonpolar surface is submonolayer, patchy, and highly disordered with an isotropic Br distribution. Overall, this combination of x-ray surface scattering techniques with a novel sample preparation strategy has several advantages as a real space probe of adsorbed or covalently bound biomolecules at the liquid-solid interface.