TY  - JOUR
A1  - Liebig, Ferenc
A1  - Henning, Ricky
A1  - Sarhan, Radwan Mohamed
A1  - Prietzel, Claudia Christina
A1  - Schmitt, Clemens Nikolaus Zeno
A1  - Bargheer, Matias
A1  - Koetz, Joachim
T1  - A simple one-step procedure to synthesise gold nanostars in concentrated aqueous surfactant solutions
JF  - RSC Advances
N2  - Due to the enhanced electromagnetic field at the tips of metal nanoparticles, the spiked structure of gold nanostars (AuNSs) is promising for surface-enhanced Raman scattering (SERS). Therefore, the challenge is the synthesis of well designed particles with sharp tips. The influence of different surfactants, i.e., dioctyl sodium sulfosuccinate (AOT), sodium dodecyl sulfate (SDS), and benzylhexadecyldimethylammonium chloride (BDAC), as well as the combination of surfactant mixtures on the formation of nanostars in the presence of Ag⁺ ions and ascorbic acid was investigated. By varying the amount of BDAC in mixed micelles the core/spike-shell morphology of the resulting AuNSs can be tuned from small cores to large ones with sharp and large spikes. The concomitant red-shift in the absorption toward the NIR region without losing the SERS enhancement enables their use for biological applications and for time-resolved spectroscopic studies of chemical reactions, which require a permanent supply with a fresh and homogeneous solution. HRTEM micrographs and energy-dispersive X-ray (EDX) experiments allow us to verify the mechanism of nanostar formation according to the silver underpotential deposition on the spike surface in combination with micelle adsorption.
KW  - optical-properties
KW  - nanoparticles
KW  - sers
KW  - ultrafast
KW  - size
KW  - nanotriangles
KW  - nanoflowers
KW  - wavelength
Y1  - 2019
U6  - https://doi.org/10.1039/C9RA02384D
SN  - 2046-2069
VL  - 9
SP  - 23633
EP  - 23641
PB  - RSC Publishing
CY  - London
ER  - 
TY  - JOUR
A1  - Ozcelikay, Goksu
A1  - Kurbanoglu, Sevinc
A1  - Yarman, Aysu
A1  - Scheller, Frieder W.
A1  - Ozkan, Sibel A.
T1  - Au-Pt nanoparticles based molecularly imprinted nanosensor for electrochemical detection of the lipopeptide antibiotic drug Daptomycin
JF  - Sensors and actuators : B, Chemical
N2  - In this work, a novel electrochemical molecularly imprinted polymer (MIP) sensor for the detection of the lipopeptide antibiotic Daptomycin (DAP) is presented which integrates gold decorated platinum nanoparticles (Au-Pt NPs) into the nanocomposite film. The sensor was prepared by electropolymerization of o-phenylenediamine (o-PD) in the presence of DAP using cyclic voltammetry. Cyclic voltammetry and differential pulse voltammetry were applied to follow the changes in the MIP-layer related to rebinding and removal of the target DAP by using the redox marker [Fe(CN)(6)](3-/4-). Under optimized operational conditions, the MIP/Au-Pt NPs/ GCE nanosensor exhibits a linear response in the range of 1-20 pM towards DAP. The limit of detection and limit of quantification were determined to be 0.161pM +/- 0.012 and 0.489pM +/- 0.012, respectively. The sensitivity towards the antibiotics Vancomycin and Erythromycin and the amino acids glycine and tryptophan was below 7 percent as compared with DAP. Moreover, the nanosensor was also successfully used for the detection of DAP in deproteinated human serum samples.
KW  - molecularly imprinted polymer
KW  - Daptomycin
KW  - platinum nanoparticles
KW  - gold
KW  - nanoparticles
KW  - modified electrodes
Y1  - 2020
U6  - https://doi.org/10.1016/j.snb.2020.128285
SN  - 0925-4005
VL  - 320
PB  - Elsevier Science
CY  - Amsterdam
ER  - 
TY  - JOUR
A1  - Gerecke, Christian
A1  - Edlich, Alexander
A1  - Giulbudagian, Michael
A1  - Schumacher, Fabian
A1  - Zhang, Nan
A1  - Said, Andre
A1  - Yealland, Guy
A1  - Lohan, Silke B.
A1  - Neumann, Falko
A1  - Meinke, Martina C.
A1  - Ma, Nan
A1  - Calderon, Marcelo
A1  - Hedtrich, Sarah
A1  - Schaefer-Korting, Monika
A1  - Kleuser, Burkhard
T1  - Biocompatibility and characterization of polyglycerol-based thermoresponsive nanogels designed as novel drug-delivery systems and their intracellular localization in keratinocytes
JF  - Nanotoxicology
N2  - Novel nanogels that possess the capacity to change their physico-chemical properties in response to external stimuli are promising drug-delivery candidates for the treatment of severe skin diseases. As thermoresponsive nanogels (tNGs) are capable of enhancing penetration through biological barriers such as the stratum corneum and are taken up by keratinocytes of human skin, potential adverse consequences of their exposure must be elucidated. In this study, tNGs were synthesized from dendritic polyglycerol (dPG) and two thermoresponsive polymers. tNG_dPG_tPG are the combination of dPG with poly(glycidyl methyl ether-co-ethyl glycidyl ether) (p(GME-co-EGE)) and tNG_dPG_pNIPAM the one with poly(N-isopropylacrylamide) (pNIPAM). Both thermoresponsive nanogels are able to incorporate high amounts of dexamethasone and tacrolimus, drugs used in the treatment of severe skin diseases. Cellular uptake, intracellular localization and the toxicological properties of the tNGs were comprehensively characterized in primary normal human keratinocytes (NHK) and in spontaneously transformed aneuploid immortal keratinocyte cell line from adult human skin (HaCaT). Laser scanning confocal microscopy revealed fluorescently labeled tNGs entered into the cells and localized predominantly within lysosomal compartments. MTT assay, comet assay and carboxy-H2DCFDA assay, demonstrated neither cytotoxic or genotoxic effects, nor any induction of reactive oxygen species of the tNGs in keratinocytes. In addition, both tNGs were devoid of eye irritation potential as shown by bovine corneal opacity and permeability (BCOP) test and red blood cell (RBC) hemolysis assay. Therefore, our study provides evidence that tNGs are locally well tolerated and underlines their potential for cutaneous drug delivery.
KW  - Drug delivery
KW  - nanoparticles
KW  - particle characterization
KW  - keratinocytes
KW  - nanotoxicology
Y1  - 2017
U6  - https://doi.org/10.1080/17435390.2017.1292371
SN  - 1743-5390
SN  - 1743-5404
VL  - 11
SP  - 267
EP  - 277
PB  - Routledge, Taylor & Francis Group
CY  - Abingdon
ER  - 
TY  - JOUR
A1  - Caetano, Daniel L. Z.
A1  - Carvalho, Sidney Jurado de
A1  - Metzler, Ralf
A1  - Cherstvy, Andrey G.
T1  - Critical adsorption of multiple polyelectrolytes onto a nanosphere
BT  - splitting the adsorption-desorption transition boundary
JF  - Interface : journal of the Royal Society
N2  - Employing extensive Monte Carlo computer simulations, we investigate in detail the properties of multichain adsorption of charged flexible polyelectrolytes (PEs) onto oppositely charged spherical nanoparticles (SNPs). We quantify the conditions of critical adsorption-the phase-separation curve between the adsorbed and desorbed states of the PEs-as a function of the SNP surface-charge density and the concentration of added salt. We study the degree of fluctuations of the PE-SNP electrostatic binding energy, which we use to quantify the emergence of the phase subtransitions, including a series of partially adsorbed PE configurations. We demonstrate how the phase-separation adsorption-desorption boundary shifts and splits into multiple subtransitions at low-salt conditions, thereby generalizing and extending the results for critical adsorption of a single PE onto the SNP. The current findings are relevant for finite concentrations of PEs around the attracting SNP, such as the conditions for PE adsorption onto globular proteins carrying opposite electric charges.
KW  - nanoparticles
KW  - polyelectrolytes
KW  - electrostatics
KW  - critical adsorption
KW  - phase-transition boundary
Y1  - 2020
U6  - https://doi.org/10.1098/rsif.2020.0199
SN  - 1742-5689
SN  - 1742-5662
VL  - 17
IS  - 167
PB  - Royal Society
CY  - London
ER  - 
TY  - JOUR
A1  - Taubert, Andreas
A1  - Stange, Franziska
A1  - Li, Zhonghao
A1  - Junginger, Mathias
A1  - Günter, Christina
A1  - Neumann, Mike
A1  - Friedrich, Alwin
T1  - CuO nanoparticles from the Strongly Hydrated Ionic Liquid Precursor (ILP) Tetrabutylammonium Hydroxide evaluation of the Ethanol Sensing Activity
JF  - ACS applied materials & interfaces
N2  - The sensing potential of CuO nanoparticles synthesized via. precipitation from a water/ionic liquid precursor (ILP) mixture was investigated. The particles have a moderate surface area of 66 m(2)/g after synthesis, which decreases upon thermal treatment to below 5 m(2)/g. Transmission electron microscopy confirms crystal growth upon annealing, likely due to sintering effects. The as-synthesized particles can be used for ethanol sensing. The respective sensors show fast response and recovery times of below 10 s and responses greater than 2.3 at 100 ppm of ethanol at 200 degrees C, which is higher than any CuO-based ethanol sensor described so far.
KW  - ionic liquids
KW  - ionic liquid precursors
KW  - tetrabutylammonium hydroxide
KW  - nanoparticles
KW  - CuO
KW  - gas sensing
Y1  - 2012
U6  - https://doi.org/10.1021/am201427q
SN  - 1944-8244
VL  - 4
IS  - 2
SP  - 791
EP  - 795
PB  - American Chemical Society
CY  - Washington
ER  - 
TY  - JOUR
A1  - Holland-Moritz, Henry
A1  - Graupner, Julia
A1  - Möller, Wolfhard
A1  - Pacholski, Claudia
A1  - Ronning, Carsten
T1  - Dynamics of nanoparticle morphology under low energy ion irradiation
JF  - Nanotechnology
N2  - If nanostructures are irradiated with energetic ions, the mechanism of sputtering becomes important when the ion range matches about the size of the nanoparticle. Gold nanoparticles with diameters of similar to 50 nm on top of silicon substrates with a native oxide layer were irradiated by gallium ions with energies ranging from 1 to 30 keV in a focused ion beam system. High resolution in situ scanning electron microscopy imaging permits detailed insights in the dynamics of the morphology change and sputter yield. Compared to bulk-like structures or thin films, a pronounced shaping and enhanced sputtering in the nanostructures occurs, which enables a specific shaping of these structures using ion beams. This effect depends on the ratio of nanoparticle size and ion energy. In the investigated energy regime, the sputter yield increases at increasing ion energy and shows a distinct dependence on the nanoparticle size. The experimental findings are directly compared to Monte Carlo simulations obtained from iradina and TRI3DYN, where the latter takes into account dynamic morphological and compositional changes of the target.
KW  - ion beam
KW  - nanoparticles
KW  - sputtering
KW  - Monte Carlo
KW  - in situ
Y1  - 2018
U6  - https://doi.org/10.1088/1361-6528/aac36c
SN  - 0957-4484
SN  - 1361-6528
VL  - 29
IS  - 31
PB  - IOP Publ. Ltd.
CY  - Bristol
ER  - 
TY  - JOUR
A1  - Cui, Qianling
A1  - Shen, Guizhi
A1  - Yan, Xuehai
A1  - Li, Lidong
A1  - Moehwald, Helmuth
A1  - Bargheer, Matias
T1  - Fabrication of Au@Pt multibranched nanoparticles and their application to in situ SERS monitoring
JF  - ACS applied materials & interfaces
N2  - Here, we present an Au@Pt core-shell multibranched nanoparticle as a new substrate capable of in situ surface-enhanced Raman scattering (SERS), thereby enabling monitoring of the catalytic reaction on the active surface. By careful control of the amount of Pt deposited bimetallic Au@Pt, nanoparticles with moderate performance both for SERS and catalytic activity were obtained. The Pt-catalyzed reduction of 4-nitrothiophenol by borohydride was chosen as the model reaction. The intermediate during the reaction was captured and clearly identified via SERS spectroscopy. We established in situ SERS spectroscopy as a promising and powerful technique to investigate in situ reactions taking place in heterogeneous catalysis.
KW  - nanoparticles
KW  - gold
KW  - core-shell nanostructure
KW  - surface-enhanced Raman scattering
KW  - heterogeneous catalysis
KW  - bimetallic nanoparticles
Y1  - 2014
U6  - https://doi.org/10.1021/am504709a
SN  - 1944-8244
VL  - 6
IS  - 19
SP  - 17075
EP  - 17081
PB  - American Chemical Society
CY  - Washington
ER  - 
TY  - JOUR
A1  - Cui, Qianling
A1  - Yashchenok, Alexey
A1  - Zhang, Lu
A1  - Li, Lidong
A1  - Masic, Admir
A1  - Wienskol, Gabriele
A1  - Moehwald, Helmuth
A1  - Bargheer, Matias
T1  - Fabrication of Bifunctional Gold/Gelatin Hybrid Nanocomposites and Their Application
JF  - ACS applied materials & interfaces
N2  - Herein, a facile method is presented to integrate large gold nanoflowers (similar to 80 nm) and small gold nanoparticles (2-4 nm) into a single entity, exhibiting both surface-enhanced Raman scattering (SERS) and catalytic activity. The as-prepared gold nanoflowers were coated by a gelatin layer, in which the gold precursor was adsorbed and in situ reduced into small gold nanoparticles. The thickness of the gelatin shell is controlled to less than 10 nm, ensuring that the small gold nanoparticles are still in a SERS-active range of the inner Au core. Therefore, the reaction catalyzed by these nanocomposites can be monitored in situ using label-free SERS spectroscopy. In addition, these bifunctional nanocomposites are also attractive candidates for application in SERS monitoring of bioreactions because of their excellent biocompatibility.
KW  - core-shell nanostructure
KW  - gold
KW  - hybrid material
KW  - gelatin
KW  - nanoparticles
KW  - surface-enhanced Raman scattering
Y1  - 2014
U6  - https://doi.org/10.1021/am5000068
SN  - 1944-8244
VL  - 6
IS  - 3
SP  - 1999
EP  - 2002
PB  - American Chemical Society
CY  - Washington
ER  - 
TY  - JOUR
A1  - Omorogie, Martins O.
A1  - Babalola, Jonathan Oyebamiji
A1  - Unuabonah, Emmanuel I.
A1  - Gong, Jian R.
T1  - Hybrid materials from agro-waste and nanoparticles: implications on the kinetics of the adsorption of inorganic pollutants
JF  - Environmental technology
N2  - This study is a first-hand report of the immobilization of Nauclea diderrichii seed waste biomass (ND) (an agro-waste) with eco-friendly mesoporous silica (MS) and graphene oxide-MS (GO+MS ) nanoparticles, producing two new hybrid materials namely: MND adsorbent for agro-waste modified with MS and GND adsorbent for agro-waste modified with GO+MS nanoparticles showed improved surface area, pore size and pore volume over those of the agro-waste. The abstractive potential of the new hybrid materials was explored for uptake of Cr(III) and Pb(II) ions. Analysis of experimental data from these new hybrid materials showed increased initial sorption rate of Cr(III) and Pb(II) ions uptake. The amounts of Cr(III) and Pb(II) ions adsorbed by MND and GND adsorbents were greater than those of ND. Modification of N. diderrichii seed waste significantly improved its rate of adsorption and diffusion coefficient for Cr(III) and Pb(II) more than its adsorption capacity. The rate of adsorption of the heavy metal ions was higher with GO+MS nanoparticles than for other adsorbents. Kinetic data were found to fit well the pseudo-second-order and the diffusion-chemisorption kinetic models suggesting that the adsorption of Cr(III) and Pb(II) onto these adsorbents is mainly through chemisorption mechanism. Analysis of kinetic data with the homogeneous particle diffusion kinetic model suggests that particle diffusion (diffusion of ions through the adsorbent) is the rate-limiting step for the adsorption process.
KW  - adsorption
KW  - graphene oxide
KW  - nanoparticles
KW  - kinetic models
KW  - hybrid materials
Y1  - 2014
U6  - https://doi.org/10.1080/09593330.2013.839747
SN  - 0959-3330
SN  - 1479-487X
VL  - 35
IS  - 5
SP  - 611
EP  - 619
PB  - Routledge, Taylor & Francis Group
CY  - Abingdon
ER  - 
TY  - JOUR
A1  - Tentschert, Jutta
A1  - Jungnickel, Harald
A1  - Reichardt, Philipp
A1  - Leube, Peter
A1  - Kretzschmar, Bernd
A1  - Taubert, Andreas
A1  - Luch, A.
T1  - Identification of nano clay in composite polymers
JF  - Surface and interface analysis : an international journal devoted to the development and application of techniques for the analysis surfaces, interfaces and thin films
N2  - Industrialized food production is in urgent search for alternative packaging materials, which can serve the requirements of a globalized world in terms of longer product shelf lives, reduced freight weight to decrease transport costs, and better barrier functionality to preserve its freshness. Polymer materials containing organically modified nano clay particles as additives are one example for a new generation of packaging materials with specific barrier functionality to actually hit the market. Clay types used for these applications are aluminosilicates, which belong to the mineral group of phyllosilicates. These consist of nano-scaled thin platelets, which are organically modified with quaternary ammonium compounds acting as spacers between the different clay layers, thereby increasing the hydrophobicity of the mineral additive. A variety of different organically modified clays are already available, and the use as additive for food packaging materials is one important application. To ensure valid risk assessments of emerging nano composite polymers used in the food packaging industry, exact analytical characterization of the organically modified clay within the polymer matrix is of paramount importance. Time-of-flight SIMS in combination with multivariate statistical analysis was used to differentiate modified clay reference materials from another. Time-of-flight SIMS spectra of a reference polymer plate, which contained one specific nano clay composite, were acquired. For each modified clay additive, a set of characteristic diagnostic ions could be identified, which then was used to successfully assign unknown clay additives to the corresponding reference material. Thus, the described methodology could be used to define and characterize nano clay within polymer matrices. Copyright (c) 2014 John Wiley & Sons, Ltd.
KW  - ToF-SIMS
KW  - nanoparticles
KW  - nano clay
KW  - polymer
KW  - food contact material
Y1  - 2014
U6  - https://doi.org/10.1002/sia.5546
SN  - 0142-2421
SN  - 1096-9918
VL  - 46
SP  - 334
EP  - 336
PB  - Wiley-Blackwell
CY  - Hoboken
ER  - 
TY  - JOUR
A1  - Wagner, Tom
A1  - Lazar, Jaroslav
A1  - Schnakenberg, Uwe
A1  - Böker, Alexander
T1  - In situ Electrothemical Impedance Spectroscopy of Electrostatically Driven Selective Gold Nanoparticle Adsorption on Block Copolymer Lamellae
JF  - Trials
N2  - Electrostatic attraction between charged nano particles and oppositely charged nanopatterned polymeric films enables tailored structuring of functional nanoscopic surfaces. The bottom-up fabrication of organic/inorganic composites for example bears promising potential toward cheap fabrication of catalysts, optical sensors, and the manufacture of miniaturized electric circuitry. However, only little is known about the time-dependent adsorption behavior and the electronic or ionic charge transfer in the film bulk and at interfaces during nanoparticle assembly via electrostatic interactions. In situ electrochemical impedance spectroscopy (EIS) in combination with a microfluidic system for fast and reproducible liquid delivery was thus applied to monitor the selective deposition of negatively charged gold nanoparticles on top of positively charged poly(2-vinylpyridinium) (qP2VP) domains of phase separated lamellar poly(styrene)-block-poly(2-vinylpyridinium) (PS-b-qP2VP) diblock copolymer thin films. The acquired impedance data delivered information with respect to interfacial charge alteration, ionic diffusion, and the charge dependent nanoparticle adsorption kinetics, considering this yet unexplored system. We demonstrate that the selective adsorption of negatively charged gold nanoparticles (AuNPs) on positively charged qP2VP domains of lamellar PS-b-qP2VP thin films can indeed be tracked by EIS. Moreover, we show that the nanoparticle adsorption kinetics and the nanoparticle packing density are functions of the charge density in the qP2VP domains.
KW  - impedance spectroscopy
KW  - block copolymers
KW  - nanoparticles
KW  - electrostatics
KW  - adsorption kinetics
Y1  - 2016
U6  - https://doi.org/10.1021/acsami.6b07708
SN  - 1944-8244
VL  - 8
SP  - 27282
EP  - 27290
PB  - American Chemical Society
CY  - Washington
ER  - 
TY  - JOUR
A1  - Gu, Sasa
A1  - Risse, Sebastian
A1  - Lu, Yan
A1  - Ballauff, Matthias
T1  - Mechanism of the oxidation of 3,3′,5,5′-tetramethylbenzidine catalyzed by peroxidase-like Pt nanoparticles immobilized in spherical polyelectrolyte brushes
BT  - a kinetic study
JF  - ChemPhysChem
N2  - Experimental and kinetic modelling studies are presented to investigate the mechanism of 3,3 ',5,5 '-tetramethylbenzidine (TMB) oxidation by hydrogen peroxide (H2O2) catalyzed by peroxidase-like Pt nanoparticles immobilized in spherical polyelectrolyte brushes (SPB-Pt). Due to the high stability of SPB-Pt colloidal, this reaction can be monitored precisely in situ by UV/VIS spectroscopy. The time-dependent concentration of the blue-colored oxidation product of TMB expressed by different kinetic models was used to simulate the experimental data by a genetic fitting algorithm. After falsifying the models with abundant experimental data, it is found that both H2O2 and TMB adsorb on the surface of Pt nanoparticles to react, indicating that the reaction follows the Langmuir-Hinshelwood mechanism. A true rate constant k, characterizing the rate-determining step of the reaction and which is independent on the amount of catalysts used, is obtained for the first time. Furthermore, it is found that the product adsorbes strongly on the surface of nanoparticles, thus inhibiting the reaction. The entire analysis provides a new perspective to study the catalytic mechanism and evaluate the catalytic activity of the peroxidase-like nanoparticles.
KW  - kinetics
KW  - nanoparticles
KW  - reaction mechanisms
KW  - spherical polyelectrolyte
KW  - brushes
KW  - UV
KW  - vis spectroscopy
Y1  - 2019
U6  - https://doi.org/10.1002/cphc.201901087
SN  - 1439-4235
SN  - 1439-7641
VL  - 21
IS  - 5
SP  - 450
EP  - 458
PB  - Wiley-VCH
CY  - Weinheim
ER  - 
TY  - JOUR
A1  - Keckeis, Philipp
A1  - Zeller, Enriko
A1  - Jung, Carina
A1  - Besirske, Patricia
A1  - Kirner, Felizitas
A1  - Ruiz-Agudo, Cristina
A1  - Schlaad, Helmut
A1  - Cölfen, Helmut
T1  - Modular toolkit of multifunctional block copoly(2-oxazoline)s for the synthesis of nanoparticles
JF  - Chemistry - a European journal
N2  - Post-polymerization modification provides an elegant way to introduce chemical functionalities onto macromolecules to produce tailor-made materials with superior properties. This concept was adapted to well-defined block copolymers of the poly(2-oxazoline) family and demonstrated the large potential of these macromolecules as universal toolkit for numerous applications. Triblock copolymers with separated water-soluble, alkyne- and alkene-containing segments were synthesized and orthogonally modified with various low-molecular weight functional molecules by copper(I)-catalyzed azide-alkyne cycloaddition (CuAAC) and thiol-ene (TE) click reactions, respectively. Representative toolkit polymers were used for the synthesis of gold, iron oxide and silica nanoparticles.
KW  - block copolymers
KW  - click chemistry
KW  - nanoparticles
KW  - ring-opening
KW  - polymerization
KW  - surfactants
Y1  - 2021
U6  - https://doi.org/10.1002/chem.202101327
SN  - 0947-6539
SN  - 1521-3765
VL  - 27
IS  - 32
SP  - 8283
EP  - 8287
PB  - Wiley-VCH
CY  - Weinheim
ER  - 
TY  - JOUR
A1  - Dey, Pradip
A1  - Bergmann, Tobias
A1  - Cuellar-Camacho, Jose Luis
A1  - Ehrmann, Svenja
A1  - Chowdhury, Mohammad Suman
A1  - Zhang, Minze
A1  - Dahmani, Ismail
A1  - Haag, Rainer
A1  - Azad, Walid
T1  - Multivalent flexible nanogels exhibit broad-spectrum antiviral activity by blocking virus entry
JF  - ACS nano
N2  - The entry process of viruses into host cells is complex and involves stable but transient multivalent interactions with different cell surface receptors. The initial contact of several viruses begins with attachment to heparan sulfate (HS) proteoglycans on the cell surface, which results in a cascade of events that end up with virus entry. The development of antiviral agents based on multivalent interactions to shield virus particles and block initial interactions with cellular receptors has attracted attention in antiviral research. Here, we designed nanogels with different degrees of flexibility based on dendritic polyglycerol sulfate to mimic cellular HS. The designed nanogels are nontoxic and broad-spectrum, can multivalently interact with viral glycoproteins, shield virus surfaces, and efficiently block infection. We also visualized virus-nanogel interactions as well as the uptake of nanogels by the cells through clathrin-mediated endocytosis using confocal microscopy. As many human viruses attach to the cells through HS moieties, we introduce our flexible nanogels as robust inhibitors for these viruses.
KW  - multivalent
KW  - herpes simplex virus
KW  - heparan sulfate
KW  - nanoparticles
KW  - click chemistry
KW  - polyglycerol
Y1  - 2018
U6  - https://doi.org/10.1021/acsnano.8b01616
SN  - 1936-0851
SN  - 1936-086X
VL  - 12
IS  - 7
SP  - 6429
EP  - 6442
PB  - American Chemical Society
CY  - Washington
ER  - 
TY  - JOUR
A1  - Hass, Roland
A1  - Reich, Oliver
T1  - Photon density wave spectroscopy for dilution-free sizing of highly concentrated nanoparticles during starved-feed polymerization
JF  - ChemPhysChem : a European journal of chemical physics and physical chemistry
KW  - analytical methods
KW  - fiber-optical spectroscopy
KW  - nanoparticles
KW  - photon density wave spectroscopy
KW  - polymerization
Y1  - 2011
U6  - https://doi.org/10.1002/cphc.201100323
SN  - 1439-4235
VL  - 12
IS  - 14
SP  - 2572
EP  - 2575
PB  - Wiley-Blackwell
CY  - Malden
ER  - 
TY  - JOUR
A1  - Dai, Xiaolin
A1  - Mate, Diana M.
A1  - Glebe, Ulrich
A1  - Garakani, Tayebeh Mirzaei
A1  - Körner, Andrea
A1  - Schwaneberg, Ulrich
A1  - Böker, Alexander
T1  - Sortase-mediated ligation of purely artificial building blocks
JF  - Polymers
N2  - Sortase A (SrtA) from Staphylococcus aureus has been often used for ligating a protein with other natural or synthetic compounds in recent years. Here we show that SrtA-mediated ligation (SML) is universally applicable for the linkage of two purely artificial building blocks. Silica nanoparticles (NPs), poly(ethylene glycol) and poly(N-isopropyl acrylamide) are chosen as synthetic building blocks. As a proof of concept, NP-polymer, NP-NP, and polymer-polymer structures are formed by SrtA catalysis. Therefore, the building blocks are equipped with the recognition sequence needed for SrtA reaction-the conserved peptide LPETG-and a pentaglycine motif. The successful formation of the reaction products is shown by means of transmission electron microscopy (TEM), matrix assisted laser desorption ionization-time of flight mass spectrometry (MALDI-ToF MS), and dynamic light scattering (DLS). The sortase catalyzed linkage of artificial building blocks sets the stage for the development of a new approach to link synthetic structures in cases where their synthesis by established chemical methods is complicated.
KW  - sortase-mediated ligation
KW  - enzymes
KW  - block copolymers
KW  - nanoparticles
Y1  - 2018
U6  - https://doi.org/10.3390/polym10020151
SN  - 2073-4360
VL  - 10
IS  - 2
PB  - MDPI
CY  - Basel
ER  - 
TY  - JOUR
A1  - Metzler, Ralf
T1  - Superstatistics and non-Gaussian diffusion
JF  - The European physical journal special topics
N2  - Brownian motion and viscoelastic anomalous diffusion in homogeneous environments are intrinsically Gaussian processes. In a growing number of systems, however, non-Gaussian displacement distributions of these processes are being reported. The physical cause of the non-Gaussianity is typically seen in different forms of disorder. These include, for instance, imperfect "ensembles" of tracer particles, the presence of local variations of the tracer mobility in heteroegenous environments, or cases in which the speed or persistence of moving nematodes or cells are distributed. From a theoretical point of view stochastic descriptions based on distributed ("superstatistical") transport coefficients as well as time-dependent generalisations based on stochastic transport parameters with built-in finite correlation time are invoked. After a brief review of the history of Brownian motion and the famed Gaussian displacement distribution, we here provide a brief introduction to the phenomenon of non-Gaussianity and the stochastic modelling in terms of superstatistical and diffusing-diffusivity approaches.
KW  - Brownian diffusion
KW  - anomalous diffusion
KW  - dynamics
KW  - kinetic-theory
KW  - models
KW  - motion
KW  - nanoparticles
KW  - nonergodicity
KW  - statistics
KW  - subdiffusion
Y1  - 2020
U6  - https://doi.org/10.1140/epjst/e2020-900210-x
SN  - 1951-6355
SN  - 1951-6401
VL  - 229
IS  - 5
SP  - 711
EP  - 728
PB  - Springer
CY  - Heidelberg
ER  - 
TY  - JOUR
A1  - Sarhan, Radwan Mohamed
A1  - Koopman, Wouter-Willem Adriaan
A1  - Schuetz, Roman
A1  - Schmid, Thomas
A1  - Liebig, Ferenc
A1  - Koetz, Joachim
A1  - Bargheer, Matias
T1  - The importance of plasmonic heating for the plasmondriven photodimerization of 4-nitrothiophenol
JF  - Scientific Reports
N2  - Metal nanoparticles form potent nanoreactors, driven by the optical generation of energetic electrons and nanoscale heat. The relative influence of these two factors on nanoscale chemistry is strongly debated. This article discusses the temperature dependence of the dimerization of 4-nitrothiophenol (4-NTP) into 4,4′-dimercaptoazobenzene (DMAB) adsorbed on gold nanoflowers by Surface-Enhanced Raman Scattering (SERS). Raman thermometry shows a significant optical heating of the particles. The ratio of the Stokes and the anti-Stokes Raman signal moreover demonstrates that the molecular temperature during the reaction rises beyond the average crystal lattice temperature of the plasmonic particles. The product bands have an even higher temperature than reactant bands, which suggests that the reaction proceeds preferentially at thermal hot spots. In addition, kinetic measurements of the reaction during external heating of the reaction environment yield a considerable rise of the reaction rate with temperature. Despite this significant heating effects, a comparison of SERS spectra recorded after heating the sample by an external heater to spectra recorded after prolonged illumination shows that the reaction is strictly photo-driven. While in both cases the temperature increase is comparable, the dimerization occurs only in the presence of light. Intensity dependent measurements at fixed temperatures confirm this finding.
KW  - enhanced raman-scattering
KW  - charge-transfer
KW  - metal
KW  - nanoparticles
KW  - catalysis
KW  - AU
KW  - 4-nitrobenzenethiol
KW  - aminothiophenol
KW  - photocatalysis
KW  - wavelength
Y1  - 2019
U6  - https://doi.org/10.1038/s41598-019-38627-2
SN  - 2045-2322
VL  - 9
PB  - Macmillan Publishers Limited
CY  - London
ER  - 
TY  - JOUR
A1  - Zou, Hua
A1  - Schlaad, Helmut
T1  - Thermoresponsive PNIPAM/Silica Nanoparticles by Direct Photopolymerization in Aqueous Media
JF  - Journal of polymer science : A, Polymer chemistry
N2  - This article presents a simple and facile method to fabricate thermoresponsive polymer-grafted silica particles by direct surface-initiated photopolymerization of N-isopropylacrylamide (NIPAM). This method is based on silica particles bearing thiol functionalities, which are transformed into thiyl radicals by irradiation with UV light to initiate the polymerization of NIPAM in aqueous media at room temperature. The photopolymerization of NIPAM could be applied to smaller thiol-functionalized particles (approximate to 48 nm) as well as to larger particles (approximate to 692 nm). Hollow poly(NIPAM) capsules could be formed after etching away the silica cores from the composite particles. It is possible to produce tailor-made composite particles or capsules for particular applications by extending this approach to other vinyl monomers. (c) 2015 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 2015, 53, 1260-1267
KW  - nanocomposites
KW  - nanoparticles
KW  - photopolymerization
KW  - silica nanoparticles
KW  - surface-initiated photopolymerization
KW  - thermoresponsive
KW  - thiol
Y1  - 2015
U6  - https://doi.org/10.1002/pola.27593
SN  - 0887-624X
SN  - 1099-0518
VL  - 53
IS  - 10
SP  - 1260
EP  - 1267
PB  - Wiley-Blackwell
CY  - Hoboken
ER  - 
TY  - JOUR
A1  - Draude, F.
A1  - Galla, S.
A1  - Pelster, Axel
A1  - Tentschert, J.
A1  - Jungnickel, H.
A1  - Haase, Alfred
A1  - Mantion, Alexandre
A1  - Thuenemann, Andreas F.
A1  - Taubert, Andreas
A1  - Luch, A.
A1  - Arlinghaus, H. F.
T1  - ToF-SIMS and Laser-SNMS analysis of macrophages after exposure to silver nanoparticles
JF  - Surface and interface analysis : an international journal devoted to the development and application of techniques for the analysis surfaces, interfaces and thin films
N2  - Silver nanoparticles (SNPs) are among the most commercialized nanoparticles because of their antibacterial effects. Besides being employed, e. g. as a coatingmaterial for sterile surfaces in household articles and appliances, the particles are also used in a broad range of medical applications. Their antibacterial properties make SNPs especially useful for wound disinfection or as a coating material for prostheses and surgical instruments. Because of their optical characteristics, the particles are of increasing interest in biodetection as well. Despite the widespread use of SNPs, there is little knowledge of their toxicity. Time-of-flight secondary ion mass spectrometry (ToF-SIMS) and laser post-ionization secondary neutral mass spectrometry (Laser-SNMS) were used to investigate the effects of SNPs on human macrophages derived from THP-1 cells in vitro. For this purpose, macrophages were exposed to SNPs. The SNP concentration ranges were chosen with regard to functional impairments of the macrophages. To optimize the analysis of the macrophages, a special silicon wafer sandwich preparation technique was employed; ToF-SIMS was employed to characterize fragments originating from macrophage cell membranes. With the use of this optimized sample preparation method, the SNP-exposed macrophages were analyzed with ToF-SIMS and with Laser-SNMS. With Laser-SNMS, the three-dimensional distribution of SNPs in cells could be readily detected with very high efficiency, sensitivity, and submicron lateral resolution. We found an accumulation of SNPs directly beneath the cell membrane in a nanoparticular state as well as agglomerations of SNPs inside the cells.
KW  - Laser-SNMS
KW  - ToF-SIMS
KW  - life sciences
KW  - imaging
KW  - nanoparticles
KW  - three-dimensional depth profiling
Y1  - 2013
U6  - https://doi.org/10.1002/sia.4902
SN  - 0142-2421
VL  - 45
IS  - 1
SP  - 286
EP  - 289
PB  - Wiley-Blackwell
CY  - Hoboken
ER  - 
TY  - JOUR
A1  - Koshkina, Olga
A1  - Westmeier, Dana
A1  - Lang, Thomas
A1  - Bantz, Christoph
A1  - Hahlbrock, Angelina
A1  - Würth, Christian
A1  - Resch-Genger, Ute
A1  - Braun, Ulrike
A1  - Thiermann, Raphael
A1  - Weise, Christoph
A1  - Eravci, Murat
A1  - Mohr, Benjamin
A1  - Schlaad, Helmut
A1  - Stauber, Roland H.
A1  - Docter, Dominic
A1  - Bertin, Annabelle
A1  - Maskos, Michael
T1  - Tuning the Surface of Nanoparticles: Impact of Poly(2-ethyl-2-oxazoline) on Protein Adsorption in Serum and Cellular Uptake
JF  - Macromolecular bioscience
N2  - Due to the adsorption of biomolecules, the control of the biodistribution of nanoparticles is still one of the major challenges of nanomedicine. Poly(2-ethyl-2-oxazoline) (PEtOx) for surface modification of nanoparticles is applied and both protein adsorption and cellular uptake of PEtOxylated nanoparticles versus nanoparticles coated with poly(ethylene glycol) (PEG) and non-coated positively and negatively charged nanoparticles are compared. Therefore, fluorescent poly(organosiloxane) nanoparticles of 15 nm radius are synthesized, which are used as a scaffold for surface modification in a grafting onto approach. With multi-angle dynamic light scattering, asymmetrical flow field-flow fractionation, gel electrophoresis, and liquid chromatography-mass spectrometry, it is demonstrated that protein adsorption on PEtOxylated nanoparticles is extremely low, similar as on PEGylated nanoparticles. Moreover, quantitative microscopy reveals that PEtOxylation significantly reduces the non-specific cellular uptake, particularly by macrophage-like cells. Collectively, studies demonstrate that PEtOx is a very effective alternative to PEG for stealth modification of the surface of nanoparticles.
KW  - cellular uptake
KW  - nanoparticles
KW  - poly(2-ethyl-2oxazoline)
KW  - poly(ethylene glycol)
KW  - protein adsorption
Y1  - 2016
U6  - https://doi.org/10.1002/mabi.201600074
SN  - 1616-5187
SN  - 1616-5195
VL  - 16
SP  - 1287
EP  - 1300
PB  - Wiley-VCH
CY  - Weinheim
ER  -