@article{garcía-lópez_chen_nilewski_duret_aliyan_kolomeisky_robinson_wang_pal_tour_2017, title={Molecular machines open cell membranes}, volume={548}, ISSN={0028-0836 1476-4687}, url={http://dx.doi.org/10.1038/NATURE23657}, DOI={10.1038/nature23657}, abstractNote={Beyond the more common chemical delivery strategies, several physical techniques are used to open the lipid bilayers of cellular membranes. These include using electric and magnetic fields, temperature, ultrasound or light to introduce compounds into cells, to release molecular species from cells or to selectively induce programmed cell death (apoptosis) or uncontrolled cell death (necrosis). More recently, molecular motors and switches that can change their conformation in a controlled manner in response to external stimuli have been used to produce mechanical actions on tissue for biomedical applications. Here we show that molecular machines can drill through cellular bilayers using their molecular-scale actuation, specifically nanomechanical action. Upon physical adsorption of the molecular motors onto lipid bilayers and subsequent activation of the motors using ultraviolet light, holes are drilled in the cell membranes. We designed molecular motors and complementary experimental protocols that use nanomechanical action to induce the diffusion of chemical species out of synthetic vesicles, to enhance the diffusion of traceable molecular machines into and within live cells, to induce necrosis and to introduce chemical species into live cells. We also show that, by using molecular machines that bear short peptide addends, nanomechanical action can selectively target specific cell-surface recognition sites. Beyond the in vitro applications demonstrated here, we expect that molecular machines could also be used in vivo, especially as their design progresses to allow two-photon, near-infrared and radio-frequency activation.}, number={7669}, journal={Nature}, publisher={Springer Science and Business Media LLC}, author={García-López, Víctor and Chen, Fang and Nilewski, Lizanne G. and Duret, Guillaume and Aliyan, Amir and Kolomeisky, Anatoly B. and Robinson, Jacob T. and Wang, Gufeng and Pal, Robert and Tour, James M.}, year={2017}, month={Aug}, pages={567–572} }
 @article{jin_garcia-lopez_chen_tour_wang_2016, title={Imaging Single Molecular Machines Attached with Two BODIPY Dyes at the Air-Solid Interface: High Probability of Single-Step-Like Photobleaching and Nonscaling Intensity}, volume={120}, ISSN={["1932-7447"]}, DOI={10.1021/acs.jpcc.6b07518}, abstractNote={Single-molecule fluorescence microscopy (SMFM) is a powerful technique in monitoring single molecular machine actions at ambient conditions. To improve the fluorescence intensity and photostability, one strategy is to attach multiple dyes to the same single molecular machine. However, it is unclear how the fluorescence property of the dyes will change when multiple dyes are compacted into the same molecule within a distance between them of ∼2 nm. In this study, we investigated the photophysics of two types of single molecular machines that are each equipped with two BODIPY dyes with different distances. We found that at the air–glass interface, single molecules attached with two dyes have a high tendency to show a single-step-like photobleaching, making them to appear like a single dye. We propose that the product of the first photobleaching event, possibly a superoxide anion radical, is involved in the destruction of the neighboring dye. In addition, the fluorescence intensity of the two-dye system does ...}, number={46}, journal={JOURNAL OF PHYSICAL CHEMISTRY C}, author={Jin, Tao and Garcia-Lopez, Victor and Chen, Fang and Tour, James and Wang, Gufeng}, year={2016}, month={Nov}, pages={26522–26531} }
 @article{chen_neupane_li_su_wang_2016, title={Investigating axial diffusion in cylindrical pores using confocal single-particle fluorescence correlation spectroscopy}, volume={37}, ISSN={["1522-2683"]}, DOI={10.1002/elps.201600158}, abstractNote={We explored the feasibility of using confocal fluorescence correlation spectroscopy to study small nanoparticle diffusion in hundred‐nanometer‐sized cylindrical pores. By modeling single particle diffusion in tube‐like confined three‐dimensional space aligned parallel to the confocal optical axis, we showed that two diffusion dynamics can be observed in both original intensity traces and the autocorrelation functions (ACFs): the confined two‐dimensional lateral diffusion and the unconfined one‐dimensional (1D) axial diffusion. The separation of the axial and confined lateral diffusion dynamics provides an opportunity to study diffusions in different dimensions separately. We further experimentally studied 45 nm carboxylated polystyrene particles diffusing in 300 nm alumina pores. The experimental data showed consistency with the simulation. To extract the accurate axial diffusion coefficient, we found that a 1D diffusion model with a Lorentzian axial collection profile needs to be used to analyze the experimental ACFs. The diffusion of the 45 nm nanoparticles in polyethyleneglycol‐passivated 300 nm pores slowed down by a factor of ∼2, which can be satisfactorily explained by hydrodynamic frictions.}, number={15-16}, journal={ELECTROPHORESIS}, author={Chen, Fang and Neupane, Bhanu and Li, Peiyuan and Su, Wei and Wang, Gufeng}, year={2016}, month={Aug}, pages={2129–2138} }
 @article{zhao_zhong_wei_ortiz_chen_wang_2016, title={Microscopic Movement of Slow-Diffusing Nanoparticles in Cylindrical Nanopores Studied with Three-Dimensional Tracking}, volume={88}, ISSN={["1520-6882"]}, DOI={10.1021/acs.analchem.5b04944}, abstractNote={To study slow mass transport in confined environments, we developed a three-dimensional (3D) single-particle localization technique to track their microscopic movements in cylindrical nanopores. Under two model conditions, particles are retained much longer inside the pores: (1) increased solvent viscosity, which slows down the particle throughout the whole pore, and (2) increased pore wall affinity, which slows down the particle only at the wall. In viscous solvents, the particle steps decrease proportionally to the increment of the viscosity, leading to macroscopically slow diffusion. As a contrast, the particles in sticky pores are microscopically active by showing limited reduction of step sizes. A restricted diffusion mode, possibly caused by the heterogeneous environment in sticky pores, is the main reason for macroscopically slow diffusion. This study shows that it is possible to differentiate slow diffusion in confined environments caused by different mechanisms.}, number={10}, journal={ANALYTICAL CHEMISTRY}, author={Zhao, Luyang and Zhong, Yaning and Wei, Yanli and Ortiz, Nathalia and Chen, Fang and Wang, Gufeng}, year={2016}, month={May}, pages={5122–5130} }
 @article{chen_garcia-lopez_jin_neupane_chu_tour_wang_2016, title={Moving Kinetics of Nanocars with Hydrophobic Wheels on Solid Surfaces at Ambient Conditions}, volume={120}, ISSN={["1932-7447"]}, DOI={10.1021/acs.jpcc.6b01249}, abstractNote={Motivated by “driving” nanoscopic nanocars on solid substrate surfaces at ambient conditions, we studied the moving kinetics of nanocars on differently modified surfaces. Single molecule fluorescence imaging was used to track the nanocar movement so that the molecules were minimally perturbed. On freshly cleaned, hydroxylated glass surfaces, nanocars with hydrophobic adamantane wheels can diffuse with a relatively large diffusion coefficient of 7.6 × 10–16 m2/s. Both the number of moving molecules and the mobility of the moving molecules decreased over time when the sample was exposed in the air. Similar declinations in movement were observed on a poly(ethylene glycol) (PEG)-modified glass surface, but the declination rate was lowered. The slowing of molecular surface diffusion is correlated to the hydrophobicity of the surface and is likely caused by the adsorption of hydrophobic molecules from the air. A proposed sticky-spots model explains the decreasing apparent diffusion coefficient of the hydrophobi...}, number={20}, journal={JOURNAL OF PHYSICAL CHEMISTRY C}, author={Chen, Fang and Garcia-Lopez, Victor and Jin, Tao and Neupane, Bhanu and Chu, Pin-Lei E. and Tour, James and Wang, Gufeng}, year={2016}, month={May}, pages={10887–10894} }
 @article{neupane_chen_wei_fang_ligler_wang_2016, title={Nanosecond Time-Resolution Study of Gold Nanorod Rotation at the Liquid-Solid Interface}, volume={17}, ISSN={["1439-7641"]}, DOI={10.1002/cphc.201600174}, abstractNote={Abstract}, number={14}, journal={CHEMPHYSCHEM}, author={Neupane, Bhanu and Chen, Fang and Wei, Yanli and Fang, Ning and Ligler, Frances S. and Wang, Gufeng}, year={2016}, month={Jul}, pages={2218–2224} }
 @article{garcia-lopez_chiang_chen_ruan_marti_kolomeisky_wang_tour_2015, title={Unimolecular Submersible Nanomachines. Synthesis, Actuation, and Monitoring}, volume={15}, ISSN={["1530-6992"]}, DOI={10.1021/acs.nanolett.5b03764}, abstractNote={Unimolecular submersible nanomachines (USNs) bearing light-driven motors and fluorophores are synthesized. NMR experiments demonstrate that the rotation of the motor is not quenched by the fluorophore and that the motor behaves in the same manner as the corresponding motor without attached fluorophores. No photo or thermal decomposition is observed. Through careful design of control molecules with no motor and with a slow motor, we found using single molecule fluorescence correlation spectroscopy that only the molecules with fast rotating speed (MHz range) show an enhancement in diffusion by 26% when the motor is fully activated by UV light. This suggests that the USN molecules give ∼9 nm steps upon each motor actuation. A non-unidirectional rotating motor also results in a smaller, 10%, increase in diffusion. This study gives new insight into the light actuation of motorized molecules in solution.}, number={12}, journal={NANO LETTERS}, author={Garcia-Lopez, Victor and Chiang, Pinn-Tsong and Chen, Fang and Ruan, Gedeng and Marti, Angel A. and Kolomeisky, Anatoly B. and Wang, Gufeng and Tour, James M.}, year={2015}, month={Dec}, pages={8229–8239} }
 @article{neupane_chen_sun_chiu_wang_2013, title={Tuning donut profile for spatial resolution in stimulated emission depletion microscopy}, volume={84}, number={4}, journal={Review of Scientific Instruments}, author={Neupane, B. and Chen, F. and Sun, W. and Chiu, D. T. and Wang, G. F.}, year={2013} }