@article {729,
	title = {Bacterial adhesion on hybrid cationic nanoparticle-polymer brush surfaces: ionic strength tunes capture from monovalent to multivalent binding.},
	journal = {Colloids Surf B Biointerfaces},
	volume = {87},
	year = {2011},
	month = {2011 Oct 1},
	pages = {109-15},
	abstract = {This paper describes the creation of hybrid surfaces containing cationic nanoparticles and biocompatible PEG (polyethylene glycol) brushes that manipulate bacterial adhesion for potential diagnostic and implant applications. Here, \~{}10 nm cationically functionalized gold nanoparticles are immobilized randomly on negative silica surfaces at tightly controlled surface loadings, and the remaining areas are functionalized with a hydrated PEG brush, using a graft copolymer of poly-l-lysine and PEG (PLL-PEG), containing 2000 molecular weight PEG chains and roughly 30\% functionalization of the PLL. The cationic nanoparticles attract the negative surfaces of suspended Staphylococcus aureus bacteria while the PEG brush exerts a steric repulsion. With the nanoparticle and PEG brush heights on the same lengthscale, variations in ionic strength are demonstrated to profoundly influence the capture of S. aureus on these surfaces. For bacteria captured from gentle flow, a crossover from multivalent to univalent binding is demonstrated as the Debye length is increased from 1 to 4 nm. In the univalent regime, 1 um diameter spherical bacteria are captured and held by single nanoparticles. In the multivalent regime, there is an adhesion threshold in the surface density of nanoparticles needed for bacterial capture. The paper also documents an interesting effect concerning the relaxations in the PLL-PEG brush itself. For brushy surfaces containing no nanoparticles, bacterial adhesion persists on newly formed brushes, but is nearly eliminated after these brushes relax, at constant mass in buffer for 12h. Thus brushy relaxations increase biocompatibility.},
	keywords = {Bacterial Adhesion, Cations, Nanoparticles, Osmolar Concentration, Polyethylene Glycols, Polylysine, Silicon Dioxide, Staphylococcus aureus, Static Electricity, Surface Properties},
	issn = {1873-4367},
	doi = {10.1016/j.colsurfb.2011.05.010},
	author = {Fang, Bing and Gon, Saugata and Park, Myoung and Kumar, Kushi-Nidhi and Rotello, Vincent M and Nusslein, Klaus and Santore, Maria M}
}
@article {732,
	title = {The role of nano-scale heterogeneous electrostatic interactions in initial bacterial adhesion from flow: a case study with Staphylococcus aureus.},
	journal = {Colloids Surf B Biointerfaces},
	volume = {76},
	year = {2010},
	month = {2010 Apr 1},
	pages = {489-95},
	abstract = {This study investigated the initial adhesion of Staphylococcus aureus from flowing buffer onto modified albumin films with the objective of probing the influence of electrostatic heterogeneity on bacterial adhesion. Electrostatic heterogeneity, on the lengthscale of 10-100 nm, was incorporated into the protein film through the irreversible random deposition of small amounts of polycation coils to produce isolated positive "patches" on the otherwise negative albumin surface before exposure to bacteria, which also possess a net negative surface charge. The system was benchmarked against an appropriate analog using 1 microm silica spheres and the same cationic patches on a silica substrate. Bacterial adhesion from flow was measured with the surface oriented vertically to eliminate gravitational forces between the bacteria and collector. In both systems, a threshold in the surface density of polycation patches needed for bacterial (or silica particle) capture indicated multivalent binding: multiple polycation patches were needed to adhere the bacteria (particles). The shifting of the threshold to greater patch concentrations at lower ionic strengths confirmed that the electrostatic interaction area (zone of influence) was a key factor in modulating the interactions. The role of the contact area in this manner is important because it enables a quantitative explanation of counterintuitive bacterial adhesion onto net negative surfaces. The study further revealed a hydrodynamic crossover from a regime where flow aids bacterial adhesion to one where flow impedes adhesion. An explanation is put forth in terms of the relative hydrodynamic and surface forces.},
	keywords = {Adsorption, Bacterial Adhesion, Methacrylates, Nylons, Particle Size, Serum Albumin, Bovine, Silicon Dioxide, Staphylococcus aureus, Static Electricity, Surface Properties},
	issn = {1873-4367},
	doi = {10.1016/j.colsurfb.2009.12.009},
	author = {Kalasin, Surachate and Dabkowski, Jeffrey and N{\"u}sslein, Klaus and Santore, Maria M}
}
