title: Oligolayer-coated nanoparticles: impact of surface topography at the nanobio interface.
abstract: Layer-by-layer coating of nanoparticles with a layer number in the single-digit range has gained increasing attention in the field of nanomedicinal research. However, the impact of using various polyelectrolytes on oligolayer formation and, more importantly, their influence on the interaction with the biological system has not often been considered in the past. Hence, we investigated the polyelectrolyte deposition profiles and resulting surface topographies of up to three polyelectrolyte layers on a flat gold sensor surface using three different polycations, namely, poly(ethylene imine) (PEI), poly(allylamine hydrochloride) (PAH), and poly(diallylammonium chloride) (PD), each in combination with poly(styrenesulfonate) (PSS). Surface plasmon resonance spectroscopy and atomic force microscopy revealed that the PEI/PSS pair in particular showed a so-called overshoot phenomenon, which is associated with partial polyelectrolyte desorption from the surface. This is also reflected by a significant increase in the surface roughness. Then, after having transferred the oligolayer assembly onto nanoparticles of ∼32 nm, we realized that quite similar surface topographies must have emerged on a curved gold surface. A major finding was that the extent of surface roughness contributes significantly to the fashion by which the oligolayer-coated nanoparticles interact with serum proteins and associate with cells. For example, for the PEI/PSS system, both the surface roughness and protein adsorption increased by a factor of ∼12 from the second to third coating layer and, at the same time, the cell association massively decreased to only one-third. Our study shows that surface roughness, along with other particle properties such as size, shape, zeta potential, and hydrophobicity, is another decisive factor for nanoparticles in a biological context, which has indeed been discussed previously but has not to date been investigated for oligolayers.
authors: †Department for Pharmaceutical Technology, ‡Department for Analytical Chemistry and Biosensors, and ∥Institute of Experimental and Applied Physics, University of Regensburg, Universitätsstrasse 31, 93053 Regensburg, Germany.
authors: Eva-Christina
authors: EC
authors: Wurster
authors: †Department for Pharmaceutical Technology, ‡Department for Analytical Chemistry and Biosensors, and ∥Institute of Experimental and Applied Physics, University of Regensburg, Universitätsstrasse 31, 93053 Regensburg, Germany.
authors: Renate
authors: R
authors: Liebl
authors: †Department for Pharmaceutical Technology, ‡Department for Analytical Chemistry and Biosensors, and ∥Institute of Experimental and Applied Physics, University of Regensburg, Universitätsstrasse 31, 93053 Regensburg, Germany.
authors: Stefanie
authors: S
authors: Michaelis
authors: †Department for Pharmaceutical Technology, ‡Department for Analytical Chemistry and Biosensors, and ∥Institute of Experimental and Applied Physics, University of Regensburg, Universitätsstrasse 31, 93053 Regensburg, Germany.
authors: Rudolf
authors: R
authors: Robelek
authors: †Department for Pharmaceutical Technology, ‡Department for Analytical Chemistry and Biosensors, and ∥Institute of Experimental and Applied Physics, University of Regensburg, Universitätsstrasse 31, 93053 Regensburg, Germany.
authors: Daniel S
authors: DS
authors: Wastl
authors: †Department for Pharmaceutical Technology, ‡Department for Analytical Chemistry and Biosensors, and ∥Institute of Experimental and Applied Physics, University of Regensburg, Universitätsstrasse 31, 93053 Regensburg, Germany.
authors: Franz J
authors: FJ
authors: Giessibl
authors: †Department for Pharmaceutical Technology, ‡Department for Analytical Chemistry and Biosensors, and ∥Institute of Experimental and Applied Physics, University of Regensburg, Universitätsstrasse 31, 93053 Regensburg, Germany.
authors: Achim
authors: A
authors: Goepferich
authors: †Department for Pharmaceutical Technology, ‡Department for Analytical Chemistry and Biosensors, and ∥Institute of Experimental and Applied Physics, University of Regensburg, Universitätsstrasse 31, 93053 Regensburg, Germany.
authors: Miriam
authors: M
authors: Breunig
mesh_terms: D000327:Adsorption; D001798:Blood Proteins / Q000737:chemistry; D002412:Cations; D002462:Cell Membrane / Q000737:chemistry*; D020099:Coated Materials, Biocompatible / Q000138:chemical synthesis*; D006046:Gold / Q000737:chemistry*; D006367:HeLa Cells; D006801:Humans; D008422:Materials Testing; D053768:Metal Nanoparticles / Q000737:chemistry* / Q000648:ultrastructure*; D011108:Polymers / Q000737:chemistry*; D066330:Printing, Three-Dimensional; D013499:Surface Properties
chemical_list: D001798:Blood Proteins; D002412:Cations; D020099:Coated Materials, Biocompatible; D011108:Polymers; D006046:Gold
keywords: AFM; Layer-by-layer; cell association; nanoparticle; planar surface; protein adsorption