pH-Triggered release from surface-modified poly(lactic-co-glycolic acid) nanoparticles

• Manuel Häuser,
• Klaus Langer and
• Monika Schönhoff

Beilstein J. Nanotechnol. 2015, 6, 2504–2512, doi:10.3762/bjnano.6.260

• contrast, measurements performed in sodium hydroxide solution (pH 11), show a drastic swelling behaviour for PAA adsorbed at pH 3, but only a slight increase in particle size for PAA adsorbed at pH 5 and pH 7, respectively. This observation can be attributed to different chain conformations of PAA during

• adsorbs in a coiled conformation to yield a thick film. In ultrapure water (pH approx. 6), the degree of dissociation in the outermost PAA layer is increasing, causing a layer swelling due to electrostatic self-repulsion. Particularly noteworthy is the massive increase in hydrodynamic radius by more than

• 100 nm, see Table 1. This implies a significant stretching of single chains after adsorption rather than a swelling of a compact film, as schematically depicted in Figure 1. This behaviour is in agreement with earlier work, where it was shown that particle radii can increase by values on the order of

Nanoscale rippling on polymer surfaces induced by AFM manipulation

• Mario D’Acunto,
• Franco Dinelli and
• Pasqualantonio Pingue

Beilstein J. Nanotechnol. 2015, 6, 2278–2289, doi:10.3762/bjnano.6.234

• residual solvent molecules is responsible for weakening the mechanical properties. This phenomenon is known by the name of ‘plasticization’ [42]. It depends on the fact that solvent molecules are intercalated into the polymer molecules and the final result is a film swelling depending on the amount of

Fabrication of hybrid nanocomposite scaffolds by incorporating ligand-free hydroxyapatite nanoparticles into biodegradable polymer scaffolds and release studies

• Balazs Farkas,
• Marina Rodio,
• Ilaria Romano,
• Alberto Diaspro,
• Romuald Intartaglia and
• Szabolcs Beke

Beilstein J. Nanotechnol. 2015, 6, 2217–2223, doi:10.3762/bjnano.6.227

• illustrates the degradation, the scaffold swelling, and HA NPs release during degradation in Dulbecco's Modified Eagle's Medium (DMEM). In order to test the release of HA NPs from the bulk scaffolds, 20 layer of 3 mm diameter porous (400 μm pore size) scaffolds were fabricated from HA NPs–PPF resins

Nanofibers for drug delivery – incorporation and release of model molecules, influence of molecular weight and polymer structure

• Jakub Hrib,
• Jakub Sirc,
• Radka Hobzova,
• Zuzana Hampejsova,
• Zuzana Bosakova,
• Marcela Munzarova and
• Jiri Michalek

Beilstein J. Nanotechnol. 2015, 6, 1939–1945, doi:10.3762/bjnano.6.198

• variable water content between nanofibers, which is the result of their variable swelling. The release experiments revealed two trends – the release rate depends on the molecular weight of model PEGs as well as on the type of nanofibrous carrier. Although we expected that long molecules will be anchored in

In situ observation of biotite (001) surface dissolution at pH 1 and 9.5 by advanced optical microscopy

• Chiara Cappelli,
• Daniel Lamarca-Irisarri,
• Jordi Camas,
• F. Javier Huertas and
• Alexander E. S. Van Driessche

Beilstein J. Nanotechnol. 2015, 6, 665–673, doi:10.3762/bjnano.6.67

• used to study the mechanisms controlling the biotite (001) surface dissolution at pH 1 (11 and 25 °C) and pH 9.5 (50 °C). Step edges are the preferential sites of dissolution and lead to step retreat, regardless of the solution pH. At pH 1, layer swelling and peeling takes place, whereas at pH 9.5

• visible terrace limits. The darker the outline (i.e., contrast), the higher the step. The same surface reacted for ca. 17 h at pH 1 and 25 °C shows edge retreat, layer swelling and peeling (Figure 1b), the latter processes being a consequence of biotite dissolution. Aldushin et al. [10] suggested that the

• the dissolution rate is similar in all crystallographic directions. Interestingly, new dissolution fronts break away from slower moving step edges (white arrows, Figure 2b), indicating that upper layers move faster than lower ones. Basal plane swelling and a general increase of roughness were also

Conformal SiO₂ coating of sub-100 nm diameter channels of polycarbonate etched ion-track channels by atomic layer deposition

• Nicolas Sobel,
• Christian Hess,
• Manuela Lukas,
• Anne Spende,
• Bernd Stühn,
• M. E. Toimil-Molares and
• Christina Trautmann

Beilstein J. Nanotechnol. 2015, 6, 472–479, doi:10.3762/bjnano.6.48

• properties such as diameter and conformation variations due to dangling bonds, swelling, or surface charge variations from pH changes of the solution, are to a large extent unknown but can influence ion transport and the control of surface modification steps in a crucial manner. A homogeneous conformal

Multifunctional layered magnetic composites

• Maria Siglreitmeier,
• Baohu Wu,
• Tina Kollmann,
• Martin Neubauer,
• Gergely Nagy,
• Dietmar Schwahn,
• Vitaliy Pipich,
• Damien Faivre,
• Dirk Zahn,
• Andreas Fery and
• Helmut Cölfen

Beilstein J. Nanotechnol. 2015, 6, 134–148, doi:10.3762/bjnano.6.13

• protocol to the layered organic matrix does not affect the magnetic nature of the material. Swelling studies In order to probe structural changes of the nanocomposite during gelatin infiltration as well as during magnetite synthesis, swelling studies were performed. The swelling capacity of the insoluble

• nacre matrix, the gelatin infiltrated chitin matrix and the magnetic nanocomposite are shown in Figure 8. The swelling degree, Sd, is defined as: where Ws stands for the weight of the swollen sample after swelling equilibrium was reached and Wd stands for the dry weight before water uptake. In the case

• of nacre matrix infiltrated with gelatin a distinct increase in swelling can be observed as compared to the insoluble matrix alone. This effect is not surprising as gelatin alone shows a higher swelling capacity as the insoluble organic matrix. The gravimetric water uptake of the gelatin–chitin

Materials and characterization techniques for high-temperature polymer electrolyte membrane fuel cells

• Roswitha Zeis

Beilstein J. Nanotechnol. 2015, 6, 68–83, doi:10.3762/bjnano.6.8

• further increase in current density to 300 mA/cm2 and 500 mA/cm2 did not lead to a significant additional swelling of the membrane. After returning to zero current, the membrane thickness was restored to the original value before the load cycle. The swelling of the membrane can be explained by hydration

Intake of silica nanoparticles by giant lipid vesicles: influence of particle size and thermodynamic membrane state

• Florian G. Strobl,
• Florian Seitz,
• Christoph Westerhausen,
• Armin Reller,
• Adriano A. Torrano,
• Christoph Bräuchle,
• Achim Wixforth and
• Matthias F. Schneider

Beilstein J. Nanotechnol. 2014, 5, 2468–2478, doi:10.3762/bjnano.5.256

• Angelova et al. [55]. In short, lipids in the desired ratio and 0.05 mol % of the fluorescent marker DiOC14 were mixed in chloroform and spread onto indium tin oxide (ITO)-coated glass slides. The solvent is thoroughly removed through vacuum evaporation. For the swelling procedure, a chamber was assembled

Functionalized polystyrene nanoparticles as a platform for studying bio–nano interactions

• Cornelia Loos,
• Tatiana Syrovets,
• Anna Musyanovych,
• Volker Mailänder,
• Katharina Landfester,
• G. Ulrich Nienhaus and
• Thomas Simmet

Beilstein J. Nanotechnol. 2014, 5, 2403–2412, doi:10.3762/bjnano.5.250

• show signs of apoptosis at this time point [41]. These data are in agreement with the previously proposed ‘‘proton-sponge’’ hypothesis, which refers to a continuous activation of the lysosomal proton pump, lysosomal swelling and rupture by particles carrying amino groups on their surface [20][41][50

Imaging the intracellular degradation of biodegradable polymer nanoparticles

• Anne-Kathrin Barthel,
• Martin Dass,
• Melanie Dröge,
• Jens-Michael Cramer,
• Daniela Baumann,
• Markus Urban,
• Katharina Landfester,
• Volker Mailänder and
• Ingo Lieberwirth

Beilstein J. Nanotechnol. 2014, 5, 1905–1917, doi:10.3762/bjnano.5.201

• with residence time compared to the pristine particles (Figure 8A). However, for the largest residence time (336 h = 14 days), the mean PLLA diameter increased to a value way above the average pristine value. Any explanation for this is highly speculative. Swelling of the PLLA nanoparticles due to the

Experimental techniques for the characterization of carbon nanoparticles – a brief overview

• Wojciech Kempiński,
• Szymon Łoś,
• Mateusz Kempiński and
• Damian Markowski

Beilstein J. Nanotechnol. 2014, 5, 1760–1766, doi:10.3762/bjnano.5.186

• pure ACFs) to 3.33 Å and 3.30 Å for CCl4- and water-filled fibers, respectively. Such significant changes appear due to the so-called quasi-high pressure effect, which appear in confined liquids (e.g., adsorbed inside small pores). This causes swelling of pores of a certain width due to the decrease of

Non-covalent and reversible functionalization of carbon nanotubes

• Antonello Di Crescenzo,
• Valeria Ettorre and
• Antonella Fontana

Beilstein J. Nanotechnol. 2014, 5, 1675–1690, doi:10.3762/bjnano.5.178

• , makes CNTs bundles precipitation more difficult, dehydrate the CNT interface and reduce water ordering around the CNTs [71] (see Figure 4). Unlikely, in none of our simulations we have observed hydrophilic chains extending and swelling in the aqueous environment. Nevertheless, our simulations considered

Liquid fuel cells

• Grigorii L. Soloveichik

Beilstein J. Nanotechnol. 2014, 5, 1399–1418, doi:10.3762/bjnano.5.153

• current densities (10 mA/cm2) [91]. The crossover of neat IPA through the SPEEK PEM was about the same as for the 1 M solution due to lower swelling [91]. A similar LFC operating on 2 M IPA at 90 °C exhibited a high OCV (0.86 V) and achieved a peak power density of 128 mW/cm2 [89]. The cell voltage was ca

Surface topography and contact mechanics of dry and wet human skin

• Alexander E. Kovalev,
• Kirstin Dening,
• Bo N. J. Persson and
• Stanislav N. Gorb

Beilstein J. Nanotechnol. 2014, 5, 1341–1348, doi:10.3762/bjnano.5.147

• cellulose fibers. In fact, cellulose fibers exhibit elastoplastic properties very similar to the stratum corneum: Both absorb water strongly and swell by wetting, both have elastic moduli of the order of 10 MPa in the wet state and of the order of 1 GPa in the dry state [11]. The swelling (and elastic

Model systems for studying cell adhesion and biomimetic actin networks

• Dorothea Brüggemann,
• Johannes P. Frohnmayer and
• Joachim P. Spatz

Beilstein J. Nanotechnol. 2014, 5, 1193–1202, doi:10.3762/bjnano.5.131

• bilayers, which are only 4 nm thick [46]. For the preparation of GUVs several methods exist, amongst which are electroformation on platinum wires or indium tin oxide (ITO) electrodes as well as spontaneous swelling. The specifics of GUVs, their detailed preparation methods and wide ranging applications are

• embedded into GUV membranes either by mixing protein-reconstituted liposomes of 0.1 to 0.2 μm diameter with a lipid-containing oil phase (lipid cosolvent method) [49] or by swelling of a tissue-like giant vesicle film [50]. For the first time, Dezi et al. recently incorporated different transmembrane

• [55]. Sackmann and co-workers later studied GUVs with enclosed actin networks, which were formed by spontaneous swelling in a buffer containing actin monomers. They also observed shape transitions in these model cells following actin polymerisation, but osmotic effects due to the addition of MgCl2

Manipulation of isolated brain nerve terminals by an external magnetic field using D-mannose-coated γ-Fe₂O₃ nano-sized particles and assessment of their effects on glutamate transport

• Tatiana Borisova,
• Natalia Krisanova,
• Arsenii Borуsov,
• Roman Sivko,
• Ludmila Ostapchenko,
• Michal Babic and
• Daniel Horak

Beilstein J. Nanotechnol. 2014, 5, 778–788, doi:10.3762/bjnano.5.90

• through swelling-activated anion channels, cysteine/glutamate exchange, trans-membrane diffusion and volume-sensitive Cl− channels [19][20][21]. In this set of experiments, the extracellular level and unstimulated release of glutamate from nerve terminals in the presence of D-mannose-coated γ-Fe2O3

Fabrication of carbon nanomembranes by helium ion beam lithography

• Xianghui Zhang,
• Henning Vieker,
• André Beyer and
• Armin Gölzhäuser

Beilstein J. Nanotechnol. 2014, 5, 188–194, doi:10.3762/bjnano.5.20

• that an excessive exposure to He+ ions (>4000 µC/cm2) leads to a damage of the CNMs, which is attributed to the swelling of the Au substrate from ion implantation [24]. A complete cross-linking of NBPT SAMs by He+ ion irradiation requires an exposure dose of approximately 850 µC/cm2, which is roughly

Digging gold: keV He⁺ ion interaction with Au

• Vasilisa Veligura,
• Gregor Hlawacek,
• Robin P. Berkelaar,
• Raoul van Gastel,
• Harold J. W. Zandvliet and
• Bene Poelsema

Beilstein J. Nanotechnol. 2013, 4, 453–460, doi:10.3762/bjnano.4.53

• swelling of several materials (Er, Nb and Ni) under helium irradiation is compared. The general trend of the expansion is similar to the one described in this work. The initial linear expansion was found to be energy-independent as well. In the work of Terreault et al. [31], the authors studied helium

Directed deposition of silicon nanowires using neopentasilane as precursor and gold as catalyst

• Britta Kämpken,
• Verena Wulf,
• Norbert Auner,
• Marcel Winhold,
• Michael Huth,
• Daniel Rhinow and
• Andreas Terfort

Beilstein J. Nanotechnol. 2012, 3, 535–545, doi:10.3762/bjnano.3.62

• deposition of polymer films is microcontact printing [47], which is generally considered advantageous since it is an “additive” method. In this particular case the need for dichloromethane or a similar solvent makes this process unsuitable due to the well-known swelling of the stamp material with these

Micro- and mesoporous solids: From science to application

• Jörg J. Schneider

Beilstein J. Nanotechnol. 2011, 2, 774–775, doi:10.3762/bjnano.2.85

• adsorption sites and dynamics, a theoretical understanding, e.g., employing state of the art theoretical modeling techniques, is certainly necessary. The development of synthetic concepts for the formation of two-dimensional, layered, porous structures, e.g., by swelling and delamination followed by film

Dynamics of capillary infiltration of liquids into a highly aligned multi-walled carbon nanotube film

• Sławomir Boncel,
• Krzysztof Z. Walczak and
• Krzysztof K. K. Koziol

Beilstein J. Nanotechnol. 2011, 2, 311–317, doi:10.3762/bjnano.2.36

• specify the Hildebrand solubility parameter (δ) as crucial towards convenient three-modal classification: dispersion, swelling or precipitation [15][16][17][18]. For evaluation of wettability of HACNT arrays, an approach based on the direct measurement of contact angle between interfaces of nanotube film

Single-pass Kelvin force microscopy and dC/dZ measurements in the intermittent contact: applications to polymer materials

• Sergei Magonov and
• John Alexander

Beilstein J. Nanotechnol. 2011, 2, 15–27, doi:10.3762/bjnano.2.2

• selective swelling of components. Keywords: atomic force microscopy; fluoroalkanes; Kelvin force microscopy; surface potential; Introduction Atomic force microscopy (AFM) applications include high-resolution imaging, probing of local materials properties and compositional mapping of heterogeneous

• compositional mapping of organic materials and polymers. In the intermittent contact operation, proximity of the conducting probe to a sample helps in avoiding screening the sample’s electrical response by a water layer when measurements are performed at high humidity. A selective swelling of individual

• topography and surface potential changes of a thin PMMA film, Figure 7B. The study of swelling of PMMA film by different organic vapors [22] showed that methanol has a strong effect as shown by AFM. Indeed, swelling of PMMA with methanol induced changes not only in topography but also in surface potential

Sensing surface PEGylation with microcantilevers

• Natalija Backmann,
• Natascha Kappeler,
• Thomas Braun,
• François Huber,
• Hans-Peter Lang,
• Christoph Gerber and
• Roderick Y. H. Lim

Beilstein J. Nanotechnol. 2010, 1, 3–13, doi:10.3762/bjnano.1.2

• authors to study the in situ swelling and collapse of poly(methyl methacrylate) brushes, the kinetics of brush formation could not be monitored in real-time. The driving impetus behind this work is to apply microcantilever sensors operated in static mode to study in real-time (1) the kinetic aspects of

• chains into their swelling state. Discussion We have studied the behavior of 20 kDa mPEG–SH “grafted to” Au surfaces using a microcantilever array-based sensor. Consistent with XPS [8], ellipsometry [8][34], QCM [35] and AFM [36] polymer “grafting to” studies, we find that the adsorption profile of mPEG

• -swelling) is described by a reproducible tensile surface stress change with a deflection of ~110–150 nm which equates into a generated stress of ~35–45 mN/m. These results were reproducible with respect to both in situ and external references, as well as surfaces consisting of either bare Au or a Au