@article{13094, abstract = {Endocytosis is a key cellular process involved in the uptake of nutrients, pathogens, or the therapy of diseases. Most studies have focused on spherical objects, whereas biologically relevant shapes can be highly anisotropic. In this letter, we use an experimental model system based on Giant Unilamellar Vesicles (GUVs) and dumbbell-shaped colloidal particles to mimic and investigate the first stage of the passive endocytic process: engulfment of an anisotropic object by the membrane. Our model has specific ligand–receptor interactions realized by mobile receptors on the vesicles and immobile ligands on the particles. Through a series of experiments, theory, and molecular dynamics simulations, we quantify the wrapping process of anisotropic dumbbells by GUVs and identify distinct stages of the wrapping pathway. We find that the strong curvature variation in the neck of the dumbbell as well as membrane tension are crucial in determining both the speed of wrapping and the final states.}, author = {Azadbakht, Ali and Meadowcroft, Billie and Varkevisser, Thijs and Šarić, Anđela and Kraft, Daniela J.}, issn = {1530-6992}, journal = {Nano Letters}, number = {10}, pages = {4267–4273}, publisher = {American Chemical Society}, title = {{Wrapping pathways of anisotropic dumbbell particles by Giant Unilamellar Vesicles}}, doi = {10.1021/acs.nanolett.3c00375}, volume = {23}, year = {2023}, } @article{13996, abstract = {We report the observation of an anomalous nonlinear optical response of the prototypical three-dimensional topological insulator bismuth selenide through the process of high-order harmonic generation. We find that the generation efficiency increases as the laser polarization is changed from linear to elliptical, and it becomes maximum for circular polarization. With the aid of a microscopic theory and a detailed analysis of the measured spectra, we reveal that such anomalous enhancement encodes the characteristic topology of the band structure that originates from the interplay of strong spin–orbit coupling and time-reversal symmetry protection. The implications are in ultrafast probing of topological phase transitions, light-field driven dissipationless electronics, and quantum computation.}, author = {Baykusheva, Denitsa Rangelova and Chacón, Alexis and Lu, Jian and Bailey, Trevor P. and Sobota, Jonathan A. and Soifer, Hadas and Kirchmann, Patrick S. and Rotundu, Costel and Uher, Ctirad and Heinz, Tony F. and Reis, David A. and Ghimire, Shambhu}, issn = {1530-6992}, journal = {Nano Letters}, keywords = {Mechanical Engineering, Condensed Matter Physics, General Materials Science, General Chemistry, Bioengineering}, number = {21}, pages = {8970--8978}, publisher = {American Chemical Society}, title = {{All-optical probe of three-dimensional topological insulators based on high-harmonic generation by circularly polarized laser fields}}, doi = {10.1021/acs.nanolett.1c02145}, volume = {21}, year = {2021}, } @article{10866, abstract = {Recent discoveries have shown that, when two layers of van der Waals (vdW) materials are superimposed with a relative twist angle between them, the electronic properties of the coupled system can be dramatically altered. Here, we demonstrate that a similar concept can be extended to the optics realm, particularly to propagating phonon polaritons–hybrid light-matter interactions. To do this, we fabricate stacks composed of two twisted slabs of a vdW crystal (α-MoO3) supporting anisotropic phonon polaritons (PhPs), and image the propagation of the latter when launched by localized sources. Our images reveal that, under a critical angle, the PhPs isofrequency curve undergoes a topological transition, in which the propagation of PhPs is strongly guided (canalization regime) along predetermined directions without geometric spreading. These results demonstrate a new degree of freedom (twist angle) for controlling the propagation of polaritons at the nanoscale with potential for nanoimaging, (bio)-sensing, or heat management.}, author = {Duan, Jiahua and Capote-Robayna, Nathaniel and Taboada-Gutiérrez, Javier and Álvarez-Pérez, Gonzalo and Prieto Gonzalez, Ivan and Martín-Sánchez, Javier and Nikitin, Alexey Y. and Alonso-González, Pablo}, issn = {1530-6992}, journal = {Nano Letters}, keywords = {Mechanical Engineering, Condensed Matter Physics, General Materials Science, General Chemistry, Bioengineering}, number = {7}, pages = {5323--5329}, publisher = {American Chemical Society}, title = {{Twisted nano-optics: Manipulating light at the nanoscale with twisted phonon polaritonic slabs}}, doi = {10.1021/acs.nanolett.0c01673}, volume = {20}, year = {2020}, } @article{8203, abstract = {Using inelastic cotunneling spectroscopy we observe a zero field splitting within the spin triplet manifold of Ge hut wire quantum dots. The states with spin ±1 in the confinement direction are energetically favored by up to 55 μeV compared to the spin 0 triplet state because of the strong spin–orbit coupling. The reported effect should be observable in a broad class of strongly confined hole quantum-dot systems and might need to be considered when operating hole spin qubits.}, author = {Katsaros, Georgios and Kukucka, Josip and Vukušić, Lada and Watzinger, Hannes and Gao, Fei and Wang, Ting and Zhang, Jian-Jun and Held, Karsten}, issn = {1530-6992}, journal = {Nano Letters}, number = {7}, pages = {5201--5206}, publisher = {American Chemical Society}, title = {{Zero field splitting of heavy-hole states in quantum dots}}, doi = {10.1021/acs.nanolett.0c01466}, volume = {20}, year = {2020}, } @article{7166, abstract = {In the living cell, we encounter a large variety of motile processes such as organelle transport and cytoskeleton remodeling. These processes are driven by motor proteins that generate force by transducing chemical free energy into mechanical work. In many cases, the molecular motors work in teams to collectively generate larger forces. Recent optical trapping experiments on small teams of cytoskeletal motors indicated that the collectively generated force increases with the size of the motor team but that this increase depends on the motor type and on whether the motors are studied in vitro or in vivo. Here, we use the theory of stochastic processes to describe the motion of N motors in a stationary optical trap and to compute the N-dependence of the collectively generated forces. We consider six distinct motor types, two kinesins, two dyneins, and two myosins. We show that the force increases always linearly with N but with a prefactor that depends on the performance of the single motor. Surprisingly, this prefactor increases for weaker motors with a lower stall force. This counter-intuitive behavior reflects the increased probability with which stronger motors detach from the filament during strain generation. Our theoretical results are in quantitative agreement with experimental data on small teams of kinesin-1 motors.}, author = {Ucar, Mehmet C and Lipowsky, Reinhard}, issn = {1530-6992}, journal = {Nano Letters}, number = {1}, pages = {669--676}, publisher = {American Chemical Society}, title = {{Collective force generation by molecular motors is determined by strain-induced unbinding}}, doi = {10.1021/acs.nanolett.9b04445}, volume = {20}, year = {2020}, } @article{13370, abstract = {Efficient isomerization of photochromic molecules often requires conformational freedom and is typically not available under solvent-free conditions. Here, we report a general methodology allowing for reversible switching of such molecules on the surfaces of solid materials. Our method is based on dispersing photochromic compounds within polysilsesquioxane nanowire networks (PNNs), which can be fabricated as transparent, highly porous, micrometer-thick layers on various substrates. We found that azobenzene switching within the PNNs proceeded unusually fast compared with the same molecules in liquid solvents. Efficient isomerization of another photochromic system, spiropyran, from a colorless to a colored form was used to create reversible images in PNN-coated glass. The coloration reaction could be induced with sunlight and is of interest for developing “smart” windows.}, author = {Chu, Zonglin and Klajn, Rafal}, issn = {1530-6992}, journal = {Nano Letters}, keywords = {Mechanical Engineering, Condensed Matter Physics, General Materials Science, General Chemistry, Bioengineering}, number = {10}, pages = {7106--7111}, publisher = {American Chemical Society}, title = {{Polysilsesquioxane nanowire networks as an “Artificial Solvent” for reversible operation of photochromic molecules}}, doi = {10.1021/acs.nanolett.9b02642}, volume = {19}, year = {2019}, } @article{10622, abstract = {We demonstrate a method for manipulating small ensembles of vortices in multiply connected superconducting structures. A micron-size magnetic particle attached to the tip of a silicon cantilever is used to locally apply magnetic flux through the superconducting structure. By scanning the tip over the surface of the device and by utilizing the dynamical coupling between the vortices and the cantilever, a high-resolution spatial map of the different vortex configurations is obtained. Moving the tip to a particular location in the map stabilizes a distinct multivortex configuration. Thus, the scanning of the tip over a particular trajectory in space permits nontrivial operations to be performed, such as braiding of individual vortices within a larger vortex ensemble—a key capability required by many proposals for topological quantum computing.}, author = {Polshyn, Hryhoriy and Naibert, Tyler and Budakian, Raffi}, issn = {1530-6992}, journal = {Nano Letters}, keywords = {mechanical engineering, condensed matter physics, general materials science, general chemistry, bioengineering}, number = {8}, pages = {5476--5482}, publisher = {American Chemical Society}, title = {{Manipulating multivortex states in superconducting structures}}, doi = {10.1021/acs.nanolett.9b01983}, volume = {19}, year = {2019}, } @article{10359, abstract = {Biological membranes typically contain a large number of different components dispersed in small concentrations in the main membrane phase, including proteins, sugars, and lipids of varying geometrical properties. Most of these components do not bind the cargo. Here, we show that such “inert” components can be crucial for the precise control of cross-membrane trafficking. Using a statistical mechanics model and molecular dynamics simulations, we demonstrate that the presence of inert membrane components of small isotropic curvatures dramatically influences cargo endocytosis, even if the total spontaneous curvature of such a membrane remains unchanged. Curved lipids, such as cholesterol, as well as asymmetrically included proteins and tethered sugars can, therefore, actively participate in the control of the membrane trafficking of nanoscopic cargo. We find that even a low-level expression of curved inert membrane components can determine the membrane selectivity toward the cargo size and can be used to selectively target membranes of certain compositions. Our results suggest a robust and general method of controlling cargo trafficking by adjusting the membrane composition without needing to alter the concentration of receptors or the average membrane curvature. This study indicates that cells can prepare for any trafficking event by incorporating curved inert components in either of the membrane leaflets.}, author = {Curk, Tine and Wirnsberger, Peter and Dobnikar, Jure and Frenkel, Daan and Šarić, Anđela}, issn = {1530-6992}, journal = {Nano Letters}, keywords = {mechanical engineering, condensed matter physics}, number = {9}, pages = {5350--5356}, publisher = {American Chemical Society}, title = {{Controlling cargo trafficking in multicomponent membranes}}, doi = {10.1021/acs.nanolett.8b00786}, volume = {18}, year = {2018}, } @article{14303, abstract = {Scaffolded DNA origami enables the fabrication of a variety of complex nanostructures that promise utility in diverse fields of application, ranging from biosensing over advanced therapeutics to metamaterials. The broad applicability of DNA origami as a material beyond the level of proof-of-concept studies critically depends, among other factors, on the availability of large amounts of pure single-stranded scaffold DNA. Here, we present a method for the efficient production of M13 bacteriophage-derived genomic DNA using high-cell-density fermentation of Escherichia coli in stirred-tank bioreactors. We achieve phage titers of up to 1.6 × 1014 plaque-forming units per mL. Downstream processing yields up to 410 mg of high-quality single-stranded DNA per one liter reaction volume, thus upgrading DNA origami-based nanotechnology from the milligram to the gram scale.}, author = {Kick, B and Praetorius, Florian M and Dietz, H and Weuster-Botz, D}, issn = {1530-6992}, journal = {Nano Letters}, number = {7}, pages = {4672--4676}, publisher = {ACS Publications}, title = {{Efficient production of single-stranded phage DNA as scaffolds for DNA origami}}, doi = {10.1021/acs.nanolett.5b01461}, volume = {15}, year = {2015}, } @article{13416, abstract = {The reversible molecular template-directed self-assembly of gold nanoparticles (AuNPs), a process which relies solely on noncovalent bonding interactions, has been demonstrated by high-resolution transmission electron microscopy (HR-TEM). By employing a well-known host−guest binding motif, the AuNPs have been systemized into discrete dimers, trimers, and tetramers. These nanoparticulate twins, triplets, and quadruplets, which can be disassembled and reassembled either chemically or electrochemically, can be coalesced into larger, permanent polygonal structures by thermal treatment using a focused HR-TEM electron beam.}, author = {Olson, Mark A. and Coskun, Ali and Klajn, Rafal and Fang, Lei and Dey, Sanjeev K. and Browne, Kevin P. and Grzybowski, Bartosz A. and Stoddart, J. Fraser}, issn = {1530-6992}, journal = {Nano Letters}, keywords = {Mechanical Engineering, Condensed Matter Physics, General Materials Science, General Chemistry, Bioengineering}, number = {9}, pages = {3185--3190}, publisher = {American Chemical Society}, title = {{Assembly of polygonal nanoparticle clusters directed by reversible noncovalent bonding interactions}}, doi = {10.1021/nl901385c}, volume = {9}, year = {2009}, }