@article {3096,
	title = {Reply to {\textquoteright}Measuring conductivity of living Geobacter sulfurreducens biofilms{\textquoteright}.},
	journal = {Nat Nanotechnol},
	volume = {11},
	year = {2016},
	month = {2016 Nov 08},
	pages = {913-914},
	keywords = {Biofilms, Electric Conductivity, Geobacter},
	issn = {1748-3395},
	doi = {10.1038/nnano.2016.191},
	author = {Malvankar, Nikhil S and Rotello, Vincent M and Tuominen, Mark T and Lovley, Derek R}
}
@article {1416,
	title = {Antimicrobial surfaces containing cationic nanoparticles: how immobilized, clustered, and protruding cationic charge presentation affects killing activity and kinetics.},
	journal = {Colloids Surf B Biointerfaces},
	volume = {125},
	year = {2015},
	month = {2015 Jan 1},
	pages = {255-63},
	abstract = {<p>This work examines how the antimicrobial (killing) activity of net-negative surfaces depends on the presentation of antimicrobial cationic functionality: distributed versus clustered, and flat clusters versus raised clusters. Specifically, the ability to kill Staphylococcus aureus by sparsely distributed 10 nm cationic nanoparticles, immobilized on a negative surface and backfilled with a PEG (polyethylene glycol) brush, was compared with that for a dense layer of the same immobilized nanoparticles. Additionally, sparsely distributed 10 nm poly-L-lysine (PLL) coils, adsorbed to a surface to produce flat cationic \&quot;patches\&quot; and backfilled with a PEG brush were compared to a saturated adsorbed layer of PLL. The latter resembled classical uniformly cationic antimicrobial surfaces. The protrusion of the cationic clusters substantially influenced killing but the surface concentration of the clusters had minor impact, as long as bacteria adhered. When surfaces were functionalized at the minimum nanoparticle and patch densities needed for bacterial adhesion, killing activity was substantial within 30 min and nearly complete within 2 h. Essentially identical killing was observed on more densely functionalized surfaces. Surfaces containing protruding (by about 8 nm) nanoparticles accomplished rapid killing (at 30 min) compared with surfaces containing similarly cationic but flat features (PLL patches). Importantly, the overall surface density of cationic functionality within the clusters was lower than reported thresholds for antimicrobial action. Also surprising, the nanoparticles were far more deadly when surface-immobilized compared with free in solution. These findings support a killing mechanism involving interfacial stress.</p>
},
	issn = {1873-4367},
	doi = {10.1016/j.colsurfb.2014.10.043},
	author = {Fang, Bing and Jiang, Ying and N{\"u}sslein, Klaus and Rotello, Vincent M and Santore, Maria M}
}
@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 {725,
	title = {Using flow to switch the valency of bacterial capture on engineered surfaces containing immobilized nanoparticles.},
	journal = {Langmuir},
	volume = {28},
	year = {2012},
	month = {2012 May 22},
	pages = {7803-10},
	abstract = {Toward an understanding of nanoparticle-bacterial interactions and the development of sensors and other substrates for controlled bacterial adhesion, this article describes the influence of flow on the initial stages of bacterial capture (Staphylococcus aureus) on surfaces containing cationic nanoparticles. A PEG (poly(ethylene glycol)) brush on the surface around the nanoparticles sterically repels the bacteria. Variations in ionic strength tune the Debye length from 1 to 4 nm, increasing the strength and range of the nanoparticle attractions toward the bacteria. At relatively high ionic strengths (physiological conditions), bacterial capture requires several nanoparticle-bacterial contacts, termed "multivalent capture". At low ionic strength and gentle wall shear rates (on the order of 10 s(-1)), individual bacteria can be captured and held by single surface-immobilized nanoparticles. Increasing the flow rate to 50 s(-1) causes a shift from monovalent to divalent capture. A comparison of experimental capture efficiencies with statistically determined capture probabilities reveals the initial area of bacteria-surface interaction, here about 50 nm in diameter for a Debye length κ(-1) of 4 nm. Additionally, for κ(-1) = 4 nm, the net per nanoparticle binding energies are strong but highly shear-sensitive, as is the case for biological ligand-receptor interactions. Although these results have been obtained for a specific system, they represent a regime of behavior that could be achieved with different bacteria and different materials, presenting an opportunity for further tuning of selective interactions. These finding suggest the use of surface elements to manipulate individual bacteria and nonfouling designs with precise but finite bacterial interactions.},
	issn = {1520-5827},
	doi = {10.1021/la205080y},
	author = {Fang, Bing and Gon, Saugata and Park, Myoung-Hwan and Kumar, Kushi-Nidhi and Rotello, Vincent M and N{\"u}sslein, Klaus and Santore, Maria M}
}
@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 {418,
	title = {Tunable metallic-like conductivity in microbial nanowire networks.},
	journal = {Nat Nanotechnol},
	volume = {6},
	year = {2011},
	month = {2011 Sep},
	pages = {573-9},
	abstract = {Electronic nanostructures made from natural amino acids are attractive because of their relatively low cost, facile processing and absence of toxicity. However, most materials derived from natural amino acids are electronically insulating. Here, we report metallic-like conductivity in films of the bacterium Geobacter sulfurreducens and also in pilin nanofilaments (known as microbial nanowires) extracted from these bacteria. These materials have electronic conductivities of \~{}5~mS~cm(-1), which are comparable to those of synthetic metallic nanostructures. They can also conduct over distances on the centimetre scale, which is thousands of times the size of a bacterium. Moreover, the conductivity of the biofilm can be tuned by regulating gene expression, and also by varying the gate voltage in a transistor configuration. The conductivity of the nanofilaments has a temperature dependence similar to that of a disordered metal, and the conductivity could be increased by processing.},
	keywords = {Electric Conductivity, Geobacter, Nanowires, Transistors, Electronic},
	issn = {1748-3395},
	doi = {10.1038/nnano.2011.119},
	author = {Malvankar, Nikhil S and Vargas, Madeline and Nevin, Kelly P and Franks, Ashley E and Leang, Ching and Kim, Byoung-Chan and Inoue, Kengo and Mester, T{\"u}nde and Covalla, Sean F and Johnson, Jessica P and Rotello, Vincent M and Tuominen, Mark T and Lovley, Derek R}
}
@article {487,
	title = {Electricity generation by Geobacter sulfurreducens attached to gold electrodes.},
	journal = {Langmuir},
	volume = {24},
	year = {2008},
	month = {2008 Apr 15},
	pages = {4376-9},
	abstract = {The versatility of gold for electrode manufacture suggests that it could be an ideal material for some microbial fuel cell applications. However, previous studies have suggested that microorganisms that readily transfer electrons to graphite do not transfer electrons to gold. Investigations with Geobacter sulfurreducens demonstrated that it could grow on gold anodes producing current nearly as effectively as with graphite anodes. Current production was associated with the development of G. sulfurreducens biofilms up to 40 microm thick. No current was produced if pilA, the gene for the structural protein of the conductive pili of G. sulfurreducens, was deleted. The finding that gold is a suitable anode material for microbial fuel cells offers expanded possibilities for the construction of microbial fuel cells and the electrochemical analysis of microbe-electrode interactions.},
	keywords = {Electrodes, Electrons, Geobacter, Gold, Microscopy, Confocal, Microscopy, Electron, Scanning, Surface Properties},
	issn = {0743-7463},
	doi = {10.1021/la703469y},
	author = {Richter, Hanno and McCarthy, Kevin and Nevin, Kelly P and Johnson, Jessica P and Rotello, Vincent M and Lovley, Derek R}
}
