Nanoparticle interactions with live cells: Quantitative fluorescence microscopy of nanoparticle size effects

• Li Shang,
• Karin Nienhaus,
• Xiue Jiang,
• Linxiao Yang,
• Katharina Landfester,
• Volker Mailänder,
• Thomas Simmet and
• G. Ulrich Nienhaus

Beilstein J. Nanotechnol. 2014, 5, 2388–2397, doi:10.3762/bjnano.5.248

• ligand densities and the receptor-ligand binding energy. It competes with the energy cost required to bend the membrane, which depends on the membrane tension and the NP curvature and, therefore, on the NP size. If the overall energy balance is equivalent to a localized decrease in the Gibbs free energy

Si/Ge intermixing during Ge Stranski–Krastanov growth

• Alain Portavoce,
• Khalid Hoummada,
• Antoine Ronda,
• Dominique Mangelinck and
• Isabelle Berbezier

Beilstein J. Nanotechnol. 2014, 5, 2374–2382, doi:10.3762/bjnano.5.246

• deposition [34]. Ge islands exhibiting a Ge-rich core were shown to be related to growth conditions promoting far-from-equilibrium states, controlled by kinetic processes, which is more typical for the case of MBE growth [34]. Equilibrium is reached through free energy minimization, taking into account the

Inorganic Janus particles for biomedical applications

• Isabel Schick,
• Steffen Lorenz,
• Dominik Gehrig,
• Stefan Tenzer,
• Wiebke Storck,
• Karl Fischer,
• Dennis Strand,
• Frédéric Laquai and
• Wolfgang Tremel

Beilstein J. Nanotechnol. 2014, 5, 2346–2362, doi:10.3762/bjnano.5.244

• theory of heterogeneous nucleation, this can be achieved by decreasing the concentration of the precursor below supersaturation, at which the homogeneous nucleation would be favourable [61]. Furthermore, the additional term of Gibbs free energy for the adhesive energy at the interface between the seeds

Liquid-phase exfoliated graphene: functionalization, characterization, and applications

• Mildred Quintana,
• Jesús Iván Tapia and
• Maurizio Prato

Beilstein J. Nanotechnol. 2014, 5, 2328–2338, doi:10.3762/bjnano.5.242

• cycloaddition of benzynes were found to be energetically as strong as the attachment of hydrogen atoms, while for the 1,3-dipolar cycloaddition, the free energy of the reaction is slightly smaller [36]. Additionally, carbon atoms which localize at graphene edges are considered to be more reactive than carbon

Anticancer efficacy of a supramolecular complex of a 2-diethylaminoethyl–dextran–MMA graft copolymer and paclitaxel used as an artificial enzyme

• Yasuhiko Onishi,
• Yuki Eshita,
• Rui-Cheng Ji,
• Masayasu Onishi,
• Takashi Kobayashi,
• Masaaki Mizuno,
• Jun Yoshida and
• Naoji Kubota

Beilstein J. Nanotechnol. 2014, 5, 2293–2307, doi:10.3762/bjnano.5.238

• . Therefore, in order for an enzyme–substrate reaction to advance spontaneously, it needs to be set to free energy change: ΔG = ΔH − TΔS < 0, and enthalpy (ΔH) must also decrease greatly with the entropy (enthalpy–entropy compensation or isokinetic theory) [28]. In fact, the change of enthalpy, ΔH‡, will

Effects of surface functionalization on the adsorption of human serum albumin onto nanoparticles – a fluorescence correlation spectroscopy study

• Pauline Maffre,
• Stefan Brandholt,
• Karin Nienhaus,
• Li Shang,
• Wolfgang J. Parak and
• G. Ulrich Nienhaus

Beilstein J. Nanotechnol. 2014, 5, 2036–2047, doi:10.3762/bjnano.5.212

• structural fluctuations of the proteins and/or the polymer shell around the NPs at higher temperatures, which could cause major structural changes forming a free energy-optimized binding interface. In our earlier work, we used NPs with a chemically well-defined, carboxylic acid-functionalized surface to

• denature. In general, a protein molecule interacting with a NP may change and even completely denature if the interaction free energy is comparable or larger than the internal energy needed to stabilize its structure. Notably, proteins consist of typically a few thousand atoms but are stabilized by an

Electronic and electrochemical doping of graphene by surface adsorbates

• Hugo Pinto and
• Alexander Markevich

Beilstein J. Nanotechnol. 2014, 5, 1842–1848, doi:10.3762/bjnano.5.195

• doping of graphene occurs when certain surface adsorbates participate in electrochemical redox reactions in which graphene plays the role of an electrode. Such reactions occur spontaneously if the total Gibbs free energy is negative and the diffusion and reaction barriers are sufficiently low for the

• reaction proceed at room temperature. The total Gibbs free energy change is given by ΔG + W for p-doping and ΔG − W for n-doping, where ΔG is the free energy for the molecular reaction and W is the work function of graphene. The work function of graphene is expected to be similar to that of graphite, about

• involving H2O/O2 and graphene as in The value of ΔG of this reaction can be calculated from the tables of free energies to be −4.82 eV [19]. Under the assumption that electrons for the above reaction are taken from graphene the total Gibbs free energy change is −4.82 + W or −0.3 eV. Thus, the reaction will

Real-time monitoring of calcium carbonate and cationic peptide deposition on carboxylate-SAM using a microfluidic SAW biosensor

• Anna Pohl and
• Ingrid M. Weiss

Beilstein J. Nanotechnol. 2014, 5, 1823–1835, doi:10.3762/bjnano.5.193

• the sensor to an electrical signal by the direct piezoelectric effect. The ability to easily calibrate the system with high performance [35] is essential to ensure the observed changes in the acoustic wave are indicative of changes in the system free energy which changes as a function of mass transfer

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

• as phenylethyl alcohol [38] or N-methylpyrrolidone (NMP) [39]. Indeed NMP has been demonstrated to enter the bundles during sonication and remain strongly bound to the nanotube surface. This leads to an enthalpy of mixing that is approximately zero conferring to the corresponding free energy of

• demonstrated [69] to wrap the nanotube exposing their polar domains towards the aqueous environments while favoring the contact of their hydrophobic domains with the nanotube surface. The wrapping of the SWCNTs by water-soluble polymers is a thermodynamically driven phenomenon because the free energy cost of

On the structure of grain/interphase boundaries and interfaces

• K. Anantha Padmanabhan and
• Herbert Gleiter

Beilstein J. Nanotechnol. 2014, 5, 1603–1615, doi:10.3762/bjnano.5.172

• experimental conditions are responsible for the development of the structural/basic units. The final atomic configurations within these structural/basic units will be decided by the minimization of total free energy and, depending on experimental conditions, maximization of entropy to the extent possible. The

• structural/basic units that constitute a grain/interphase boundary/interface could be a collection of different ensembles of atoms whose number, size and shape are governed by the well-known free energy equation where U is the internal energy, P the pressure, V the volume, T the absolute temperature, S the

• more than one species is present in a material, i.e., short-range order always exists. This is due to the presence of interatomic (including electronic) attractive and repulsive forces and the drive to decrease the free energy of the system. Equation 1 applies to a cluster of atoms. When it gets

The protein corona protects against size- and dose-dependent toxicity of amorphous silica nanoparticles

• Dominic Docter,
• Christoph Bantz,
• Dana Westmeier,
• Hajo J. Galla,
• Qiangbin Wang,
• James C. Kirkpatrick,
• Peter Nielsen,
• Michael Maskos and
• Roland H. Stauber

Beilstein J. Nanotechnol. 2014, 5, 1380–1392, doi:10.3762/bjnano.5.151

• nanomaterials [8]. Owing to their high surface free energy and their high surface area-to-volume ratio nanoparticles are highly reactive. Such a high reactivity to various biotic and abiotic environments, particularly the interaction of nanomaterials with biological systems and their unique physico-chemical

• understood in detail [19][20][21]. In addition, due to their high surface free energy, nanomaterials, including silica-based NP, adsorb (bio)molecules upon contact with biological or abiotic environments, forming the so-called corona [22][23]. Particularly, the biophysical properties of particles covered by

Restructuring of an Ir(210) electrode surface by potential cycling

• Khaled A. Soliman,
• Dieter M. Kolb,
• Ludwig A. Kibler and
• Timo Jacob

Beilstein J. Nanotechnol. 2014, 5, 1349–1356, doi:10.3762/bjnano.5.148

• in- and outside a UHV chamber. It was found that the presence of oxygen is crucial for the faceting process on Ir(210) [21][22]. Theoretical calculations for the Ir(210) system, based on first principles, provided supportive information. It was shown that, due to the anisotropy in surface free energy

Functionalized nanostructures for enhanced photocatalytic performance under solar light

• Liejin Guo,
• Dengwei Jing,
• Maochang Liu,
• Yubin Chen,
• Shaohua Shen,
• Jinwen Shi and
• Kai Zhang

Beilstein J. Nanotechnol. 2014, 5, 994–1004, doi:10.3762/bjnano.5.113

• hydrogen and oxygen from water splitting has a standard Gibbs free energy (ΔG) of 237 kJ/mol and is therefore an uphill reaction. Energy input is therefore indispensible for this reaction to proceed. In principle, the photocatalytic reaction over semiconductors is triggered by the direct absorption of a

Volcano plots in hydrogen electrocatalysis – uses and abuses

• Paola Quaino,
• Fernanda Juarez,
• Elizabeth Santos and
• Wolfgang Schmickler

Beilstein J. Nanotechnol. 2014, 5, 846–854, doi:10.3762/bjnano.5.96

• adsorption energy should be neither too high nor too low. If it is is too high (endothermic), adsorption is slow and limits the overall rate; if it is too low (exothermic), desorption is slow. In terms of hydrogen electrocatalysis it can be stated more precisely: at the equilibrium potential the free energy

• of adsorption of hydrogen from solution should be close to zero. If Sabatier’s principle is the only factor that governs a reaction, a plot of the reaction rate versus the free energy of adsorption of the intermediate results in a volcano curve. Starting from a high, positive (endergonic) energy of

• modern volcano plots is the only metal on the descending branch. There is a parallelism between the concept of volcano plots in catalysis and outer sphere electron transfer reactions. According to Marcus’ theory [6] a plot of the reaction rate versus the reaction free energy ΔG should pass through a

Constant chemical potential approach for quantum chemical calculations in electrocatalysis

• Wolfgang B. Schneider and
• Alexander A. Auer

Beilstein J. Nanotechnol. 2014, 5, 668–676, doi:10.3762/bjnano.5.79

• approximations by the orbital energies. Furthermore, in calculating the free energy of a system, a Fermi–Dirac distribution function is applied to obtain the occupation numbers at a given temperature (“Fermi smearing”). Here, the chemical potential appears as a parameter for the Fermi smearing in the form of the

• energy of a Canonical Ensemble equals the values that are obtained by calculating the grand potential (Equation 5) of the corresponding Grand Canonical Ensemble. Thus, the free energy and the Grand Potential can easily be converted (Equation 6). By calculating the electronic structure of an oxygen atom

• , calculated numerically and approximated by recalculation of the Fock matrix, respectively. Scheme for a potential dependent calculation of the free energy. Convergence of the number of electrons with the SCF iterations for different systems. Note that the calculation for the charge neutral molecules with

One-step synthesis of high quality kesterite Cu₂ZnSnS₄ nanocrystals – a hydrothermal approach

• Vincent Tiing Tiong,
• John Bell and
• Hongxia Wang

Beilstein J. Nanotechnol. 2014, 5, 438–446, doi:10.3762/bjnano.5.51

• will grow up to form larger crystals because the large one has lower surface free energy [30]. TGA molecules which are adsorbed on the nanocrystals surface may restrict the growth of CZTS crystals and slow down the growth process, leading to the formation of monodisperse CZTS nanocrystals. Based on the

The role of oxygen and water on molybdenum nanoclusters for electro catalytic ammonia production

• Jakob G. Howalt and
• Tejs Vegge

Beilstein J. Nanotechnol. 2014, 5, 111–120, doi:10.3762/bjnano.5.11

• theory calculations are used in combination with the computational hydrogen electrode approach to calculate the free energy profile for electrochemical protonation of O and N2 species on cuboctahedral Mo13 nanoclusters. The calculations show that the molybdenum nanocluster will preferentially bind oxygen

• the pH value is set to 0 and the values of the free energy corrections for all the oxygen containing species were found in literature [25], were the ΔEZPE –TΔS corrections for O is 0.05 eV, for OH is 0.35 eV and for H2O is 0.67 eV. A pH of, e.g., 7 would change the energy by 0.41 eV for all the

• , ranging from −0.65 eV to −0.86 eV, and nitrogen molecules are therefore preferred over hydrogen on the surface at neutral bias. At an applied potential of −0.6 V, which is the potential shown to electrochemically produce ammonia on the clean molybdenum nanocluster, the reaction free energy of adsorbing

Some reflections on the understanding of the oxygen reduction reaction at Pt(111)

• Ana M. Gómez-Marín,
• Ruben Rizo and
• Juan M. Feliu

Beilstein J. Nanotechnol. 2013, 4, 956–967, doi:10.3762/bjnano.4.108

• been suggested, with the (111) facet at the top of this curve [13][60][61][62]. Following the same procedure reported in the literature and by employing the reported theoretical ΔGOHads, ΔGOads and ΔGOOHads values [13][33][44][58], we construct the free energy diagram at 0.9 V (vs SHE) for the ORR at

• ). Incidentally, if this were true, this would be bad news for practical applications because small nanoparticles cannot contain wide {111} domains. In this picture, all the electron/transfer steps before Equation 7, or Equation 12, are downhill in terms of free energy. Exceptions are Equation 8 and Equation 9 on

• Pt(111) and Equation 6, or Equation 11, on Pt(110) but in these electrodes the OHads desorption has the largest positive free energy change in the whole mechanism. This simple picture is, however, not sufficient to explain the ORR mechanism, because the coverage of O-containing species at the surface

Challenges in realizing ultraflat materials surfaces

• Takashi Yatsui,
• Wataru Nomura,
• Fabrice Stehlin,
• Olivier Soppera,
• Makoto Naruse and
• Motoichi Ohtsu

Beilstein J. Nanotechnol. 2013, 4, 875–885, doi:10.3762/bjnano.4.99

• ]. In this study, radio frequency (RF) sputtering was used to deposit Al2O3 nanoparticles on an alumina substrate. In the case of conventional RF sputtering, the migration length of the Al2O3 nanoparticles on the substrate surface depends on the Schwöbel barrier [48] in the free energy profile. The

Large-scale atomistic and quantum-mechanical simulations of a Nafion membrane: Morphology, proton solvation and charge transport

• Pavel V. Komarov,
• Pavel G. Khalatur and
• Alexei R. Khokhlov

Beilstein J. Nanotechnol. 2013, 4, 567–587, doi:10.3762/bjnano.4.65

• +–(r) is identified with the free energy F as a function of interionic separation r at a given temperature T. The results discussed in this subsection were obtained from the simulations of our smallest (65,608-atom) system at a hydration level of 10, and the temperature ranged from 200 K to 500 K. From

• solvation shell for the ions (Figure 7). As the temperature is subsequently increased, the minimum for the contact ion pairs and solvent-separated ion pairs becomes deeper. More importantly, the main contribution to the free energy of contact ion pairs seems to be dominated by the entropy gain, not the

• potential energy contribution. To demonstrate this, we performed a thermodynamic decomposition of the potential of mean force. If the standard state for free energy is defined as that for the infinitely separated cation and anion, r→∞, then one can write where W+–(∞) = 0 and ΔS = –∂W+–(r)/∂T. The entropic

Nanoglasses: a new kind of noncrystalline materials

• Herbert Gleiter

Beilstein J. Nanotechnol. 2013, 4, 517–533, doi:10.3762/bjnano.4.61

• structure of lower stability and higher free energy. Structural model of nanoglasses In summary the structural model of metallic nanoglasses that emerges from these observations is as follows (Figure 15). Nanoglasses are noncrystalline solids consisting of the following two regions. There are regions (red

Molecular dynamics simulations of mechanical failure in polymorphic arrangements of amyloid fibrils containing structural defects

• Hlengisizwe Ndlovu,
• Alison E. Ashcroft,
• Sheena E. Radford and
• Sarah A. Harris

Beilstein J. Nanotechnol. 2013, 4, 429–440, doi:10.3762/bjnano.4.50

• binding free energy of the intersheet interface and also the enthalpy of the fibril complex devoid of solvent molecules. The three polymorphs of SNNFGAILSS sequence fibrils in the Class1-P (red), Class2-P (green) and Class6-AP (blue) symmetry-packing classes. (a) Models before the molecular dynamics

Nanoscopic surfactant behavior of the porin MspA in aqueous media

• Ayomi S. Perera,
• Hongwang Wang,
• Tej B. Shrestha,
• Deryl L. Troyer and
• Stefan H. Bossmann

Beilstein J. Nanotechnol. 2013, 4, 278–284, doi:10.3762/bjnano.4.30

• Figure 2. The hydrophobic effect is responsible for vesicle formation by MspA We describe the self-assembly process by the free energy model originally developed by C. Tanford [27] and we assume that the residual contact of the water with the hydrophobic constriction zone is negligible after vesicle

Influence of the solvent on the stability of bis(terpyridine) structures on graphite

• Daniela Künzel and
• Axel Groß

Beilstein J. Nanotechnol. 2013, 4, 269–277, doi:10.3762/bjnano.4.29

• computationally expensive statistical averages have to be performed in order to evaluate free-energy differences. Although electronic structure calculations based on density functional theory can reproduce the properties of planar arrangements of aromatic molecules satisfactorily [15][16][17][18], the large size

• a consideration of the free energies and free-energy differences. Typically, free energy differences are determined by performing constrained MD simulations using either umbrella sampling schemes [27][28], free-energy perturbation methods [29] or some other appropriate thermodynamic integration

• structures was found. Thermodynamically, the stability of the adsorbate structures is governed by the free energy. Neglecting entropic effects, the free energy of adsorption can be expressed as [13][32] where Eads is the adsorption energy per molecule in a given structure and ρ is the density of molecules

Characterization and properties of micro- and nanowires of controlled size, composition, and geometry fabricated by electrodeposition and ion-track technology

• Maria Eugenia Toimil-Molares

Beilstein J. Nanotechnol. 2012, 3, 860–883, doi:10.3762/bjnano.3.97