@article {1418,
	title = {Easy come easy go: surfaces containing immobilized nanoparticles or isolated polycation chains facilitate removal of captured Staphylococcus aureus by retarding bacterial bond maturation.},
	journal = {ACS Nano},
	volume = {8},
	year = {2014},
	month = {2014 Feb 25},
	pages = {1180-90},
	abstract = {<p>Adhesion of bacteria is a key step in the functioning of antimicrobial surfaces or certain types of on-line sensors. The subsequent removal of these bacteria, within a \&sim; 10-30 min time frame, is equally important but complicated by the tendency of bacterial adhesion to strengthen within minutes of initial capture. This study uses Staphylococcus aureus as a model bacterium to demonstrate the general strategy of clustering adhesive surface functionality (at length scales smaller than the bacteria themselves) on otherwise nonadhesive surfaces to capture and retain bacteria (easy come) while limiting the progressive strengthening of adhesion. The loose attachment facilitates bacteria removal by moderate shearing flow (easy go). This strategy is demonstrated using surfaces containing sparsely and randomly arranged immobilized amine-functionalized nanoparticles or poly-l-lysine chains, about 10 nm in size. The rest of the surface is backfilled with a nonadhesive polyethylene glycol (PEG) brush that, by itself, repels S. aureus. The nanoparticles or polymer chains cluster cationic functionality, providing small regions that attract negatively charged S. aureus cells. Compared with surfaces of nearly uniform cationic character where S. aureus adhesion quickly becomes strong (on a time scale less than 5 min), placement of cationic charge in small clusters retards or prevents processes that increase bacteria adhesion on a time scale of \&sim; 30 min, providing \&quot;easy go\&quot; surfaces.</p>
},
	keywords = {Nanoparticles, Polyamines, Staphylococcus aureus, Surface Properties},
	issn = {1936-086X},
	doi = {10.1021/nn405845y},
	author = {Fang, Bing and Jiang, Ying and Rotello, Vincent M and N{\"u}sslein, 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}
}
@article {734,
	title = {"Doubly selective" antimicrobial polymers: how do they differentiate between bacteria?},
	journal = {Chemistry},
	volume = {15},
	year = {2009},
	month = {2009 Nov 2},
	pages = {11710-4},
	abstract = {We have investigated how doubly selective synthetic mimics of antimicrobial peptides (SMAMPs), which can differentiate not only between bacteria and mammalian cells, but also between Gram-negative and Gram-positive bacteria, make the latter distinction. By dye-leakage experiments on model vesicles and complementary experiments on bacteria, we were able to relate the Gram selectivity to structural differences of these bacteria types. We showed that the double membrane of E. coli rather than the difference in lipid composition between E. coli and S. aureus was responsible for Gram selectivity. The molecular-weight-dependent antimicrobial activity of the SMAMPs was shown to be a sieving effect: while the 3000 g mol(-1) SMAMP was able to penetrate the peptidoglycan layer of the Gram-positive S. aureus bacteria, the 50000 g mol(-1) SMAMP got stuck and consequently did not have antimicrobial activity.},
	keywords = {Anti-Infective Agents, Biomimetic Materials, Escherichia coli, Microbial Sensitivity Tests, Peptidoglycan, Polymers, Staphylococcus aureus},
	issn = {1521-3765},
	doi = {10.1002/chem.200802558},
	author = {Lienkamp, Karen and Kumar, Kushi-Nidhi and Som, Abhigyan and N{\"u}sslein, Klaus and Tew, Gregory N}
}
@article {742,
	title = {Antimicrobial polymers prepared by ROMP with unprecedented selectivity: a molecular construction kit approach.},
	journal = {J Am Chem Soc},
	volume = {130},
	year = {2008},
	month = {2008 Jul 30},
	pages = {9836-43},
	abstract = {Synthetic Mimics of Antimicrobial Peptides (SMAMPs) imitate natural host-defense peptides, a vital component of the body{\textquoteright}s immune system. This work presents a molecular construction kit that allows the easy and versatile synthesis of a broad variety of facially amphiphilic oxanorbornene-derived monomers. Their ring-opening metathesis polymerization (ROMP) and deprotection provide several series of SMAMPs. Using amphiphilicity, monomer feed ratio, and molecular weight as parameters, polymers with 533 times higher selectivitiy (selecitviy = hemolytic concentration/minimum inhibitory concentration) for bacteria over mammalian cells were discovered. Some of these polymers were 50 times more selective for Gram-positive over Gram-negative bacteria while other polymers surprisingly showed the opposite preference. This kind of "double selectivity" (bacteria over mammalian and one bacterial type over another) is unprecedented in other polymer systems and is attributed to the monomer{\textquoteright}s facial amphiphilicity.},
	keywords = {Anti-Infective Agents, Antimicrobial Cationic Peptides, Biomimetic Materials, Erythrocytes, Escherichia coli, Hemolysis, Humans, Hydrophobic and Hydrophilic Interactions, Microbial Sensitivity Tests, Molecular Weight, Norbornanes, Polymers, Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization, Staphylococcus aureus, Structure-Activity Relationship},
	issn = {1520-5126},
	doi = {10.1021/ja801662y},
	author = {Lienkamp, Karen and Madkour, Ahmad E and Musante, Ashlan and Nelson, Christopher F and N{\"u}sslein, Klaus and Tew, Gregory N}
}
@article {741,
	title = {Investigating the effect of increasing charge density on the hemolytic activity of synthetic antimicrobial polymers.},
	journal = {Biomacromolecules},
	volume = {9},
	year = {2008},
	month = {2008 Oct},
	pages = {2805-10},
	abstract = {The current study is aimed at investigating the effect of fine-tuning the cationic character of synthetic mimics of antimicrobial peptides (SMAMPs) on the hemolytic and antibacterial activities. A series of novel norbornene monomers that carry one, two, or three Boc-protected amine functionalities was prepared. Ring-opening metathesis polymerization (ROMP) of the monomers, followed by deprotection of the amine groups resulted in cationic antimicrobial polynorbornenes that carry one, two, and three charges per monomer repeat unit. Increasing the number of amine groups on the most hydrophobic polymer reduced its hemolytic activity significantly. To understand the membrane activity of these polymers, we conducted dye leakage experiments on lipid vesicles that mimic bacteria and red blood cell membranes, and these results showed a strong correlation with the hemolysis data.},
	keywords = {Amines, Anti-Infective Agents, Antimicrobial Cationic Peptides, Chemistry, Pharmaceutical, Drug Design, Erythrocytes, Escherichia coli, Hemolysis, Humans, Lipids, Magnetic Resonance Spectroscopy, Models, Chemical, Peptides, Polymers, Staphylococcus aureus},
	issn = {1526-4602},
	doi = {10.1021/bm800569x},
	author = {Al-Badri, Zoha M and Som, Abhigyan and Lyon, Sarah and Nelson, Christopher F and N{\"u}sslein, Klaus and Tew, Gregory N}
}
