S-layer based biomolecular imprinting

Abstract

This work describes the development of molecularly imprinted polymer (MIP) thin films by using reassembled S-layer protein arrays as templates. Crystalline bacterial cell surface layer (S-layer) proteins are among the most abundant biopolymers on earth and form the outermost cell envelope component in a broad range of bacteria and archaea. The unique feature of S-layer based imprints is the crystalline character of the reassembled S-layer protein lattice leading to a precisely controllable periodicity of surface functional groups and topographical features. By determining the Young (elastic) modulus of the S-layer protein with respect to that of the polymer at its gel point, the feasibility of the S-layer based biomolecular imprinting was confirmed. After imprinting the polymer with an S-layer coated silicon stamp, the sensitivity of the imprints and their selectivity in relation to various other proteins were investigated by quartz crystal microbalance (QCM) studies. Furtheron, polycationic ferritin (PCF) was bound in a dense packing on the S-layer and subsequently used for stamping. Successful rebinding of PCF proved that the S-layer lattice can be used as a template for making imprints of densely packed and, probably, perfectly oriented biologically functional molecules, a concept that can in principle be extended to a wide range of other biomolecules (e.g. antibodies).

Metal ion binding and tolerance of bacteria cells in view of sensor applications

“…For YCl 3 concentrations below 1.67 × 10 −5 mol L −1 no color change was visible due to the repulsive Coulomb interactions of the positively charged surface of S-layer-functionalized AuNPs (Lakatos et al, 2015). An increase of the YCl 3 concentration induces the cross-linkage and aggregation of the S-layer-functionalized AuNPs, as indicated by the color change.…”

“…This can be explained by the increasing number of free Y ions and a saturation of all binding sites on the S-layer proteins. The mechanism of cross-linkage between the particles does not take place (Lakatos et al, 2015).…”

“…L. sphaericus JG-A12 can bind Au 3+ , Cu 2+ , Pd 2+ , Pt 2+ and U 4+ Merroun et al, 2005;Pollmann et al, 2006;Raff et al 2003), whereas L. sphaericus JG-B53 is known to bind Eu 3+ , Au 3+ , Pd 2+ and Pt 2+ with a higher affinity to Pd 2+ and Au 3+ (Suhr et al, 2014). Other concepts are based on the use of the purified S-layer proteins of these bacteria for immobilization matrices, the attachment of fusion proteins or the detection of molecules like Pt(II) porphyrin (Ladenhauf et al, 2015;Mateu et al, 2014;Neubauer et al, 1993Neubauer et al, , 1994Scheicher et al, 2009;Weinert et al, 2015).…”

“…One example is the detection of uranyl in real time by using low-frequency impedance spectroscopy (Conroy et al, 2010). Another more recent approach is the use of Slayer proteins of L. sphaericus JG-A12 to functionalize gold nanoparticles (AuNPs) and the establishment of a colorimetric sensor based on the color change by particle agglomeration in the presence of As(V) ions (Lakatos et al, 2015).…”

Ambient atomic resolution atomic force microscopy with qPlus sensors: Part 1

“…Modifications of core shell nanoparticles to create patterned hydrophilic or hydrophobic shells, need characterization of their properties in the nanometer regime (Wurster et al, ). Resolving hydrophilic and hydrophobic patterns, and the sensing of functional groups or water layer structure at the molecular scale can be realized using new developed techniques for biological samples, for example, in self‐assembled protein (s‐layer proteins) (Ladenhauf et al, ) layers in air (Wastl et al, ).…”