Biomolecular Interfaces

Ruiz-Taylor, L.A., Martin, T.L., Zaugg, F.G., Indermuhle, R, Nock, S., and Wagner, R, Monolayers of derivatized poly(L-lysine)-grafted poly(ethylene glycol) on metal oxides as a class of biomolecular interfaces, Proc. Natl. Acad. Sci. USA, 98, 852-857, 2001. 

Biochemical and biophysical activity often occurs at the interfaces of biomolecules and various types of assemblies of such molecules/ Several biomolecular interfaces considered are listed in Table 13. 

One of the typical examples of such biomolecular interfaces is a membrane , a two-dimensional molecular array which forms the boundary of biological cells. These membranes are composed of lipids and proteins. Of these, the lipid molecules which are amphipathic (a molecule consisting of two parts, each of which has an affinity for a different phase), are considered to be responsible for maintaining the two-dimensional molecular structure the protein molecules, which perform a variety of biochemical functions, are often associated with (in/on) these lipid bilayer membranes (Figure 16). 

King MR (ed) (2006) Principles of Cellular Engineering Understanding the Biomolecular Interface. Academic, San Diego Cai L, Friedman N, Xie XS (2006) Stochastic protein expression in individual cells at the single molecule level. Nature 440(04599) 358-362... 

Wang, X., E. C. Landris, R. Franking, and R. J. Hamers. Surface chemistry for stable and smart molecular and biomolecular interfaces via photochemical grafting of alkenes. Acc. Chem. Res. 43, 2010 1205-1215. 

To decipher the interaction mechanisms of small and large anions with biomolecular interfaces, it is at least initially advantageous to look at a simplified system that captures the essential physics. With the risk of dismaying readers with a biochemical background, we will now construct an artificial bio-colloid — a simple nano-sphere with distributed cationic surface charges (see Fig. 4). While we do not claim that this toy-model is an adequate proxy for a real protein, it has some appealing advantages in that... 

In this chapter we describe the basic principles involved in the controlled production and modification of two-dimensional protein crystals. These are synthesized in nature as the outermost cell surface layer (S-layer) of prokaryotic organisms and have been successfully applied as basic building blocks in a biomolecular construction kit. Most importantly, the constituent subunits of the S-layer lattices have the capability to recrystallize into iso-porous closed monolayers in suspension, at liquid-surface interfaces, on lipid films, on liposomes, and on solid supports (e.g., silicon wafers, metals, and polymers). The self-assembled monomolecular lattices have been utilized for the immobilization of functional biomolecules in an ordered fashion and for their controlled confinement in defined areas of nanometer dimension. Thus, S-layers fulfill key requirements for the development of new supramolecular materials and enable the design of a broad spectrum of nanoscale devices, as required in molecular nanotechnology, nanobiotechnology, and biomimetics [1-3]. 

Particularly attractive for numerous bioanalytical applications are colloidal metal (e.g., gold) and semiconductor quantum dot nanoparticles. The conductivity and catalytic properties of such systems have been employed for developing electrochemical gas sensors, electrochemical sensors based on molecular- or polymer-functionalized nanoparticle sensing interfaces, and for the construction of different biosensors including enzyme-based electrodes, immunosensors, and DNA sensors. Advances in the application of molecular and biomolecular functionalized metal, semiconductor, and magnetic particles for electroanalytical and bio-electroanalytical applications have been reviewed by Katz et al. [142]. 

Weissbuch, L, Zepik, H., Bolbach, G., et al. (2003). Homochiral oligopeptides by chiral amplification within two-dimensional crystalline self-assemblies at the air-water interface relevance to biomolecular handedness. Chemistry, 9 (8), 1782-94. 

Li, Z., Lazaridis, T. (2007) Water at biomolecular binding interfaces. Phys Chem ChemPhys9, 573-581. 

Electrospray ionization (ESI), a very powerful MS ionization mode, has been coupled with liquid chromatography becoming a popular tool in biomolecular analysis and drug analysis applications [1], Use of HPLC or ultra performance liquid chromatography (UPLC) combined with a mass spectrometry through the interface—ESI has become a powerful and routinely used analytical tool for many fields in scientific research, pharma industry, healthcare, and clinical diagnostic applications. 

Department of Biomolecular Systems, Max Planck Institute of Colloids and Interfaces, Potsdam, Germany... 

The versatility of the SPR technique has been shown by a vast amount of publications in the past decades the method has matured into a well-accepted analytical tool for the characterization of interfaces and thin films as well as for the sensitive detection of interfacial biomolecular interaction. With a significant input from engineering, SPR has reached a decent signal-to-noise level with a lower limit for a reliable signal detection corresponding to an effective layer of about 0.3 A [6], which is sufficient for most thin film studies. However, the intrinsic label-free characteristic of SPR detection technique still imposes limitation on further sensitivity improvement, especially if the analysis involves small molecules. 

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