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ACS Nano

Stefan Borsley, Scott L Cockroft
Monitoring current flow through a single nanopore has proved to be a powerful technique for the in situ detection of molecular structure, binding and reactivity. Transmembrane proteins, such as α-hemolysin, provide particularly attractive platforms for nanopore sensing applications due to their atomically precise structures. However, many nanopore applications require the introduction of functional groups to tune selectivity. To date, such modifications have required genetic modification of the protein prior to functionalization...
December 15, 2017: ACS Nano
Robert Walder, William J Van Patten, Ayush Adhikari, Thomas T Perkins
Single-molecule force spectroscopy (SMFS) is a powerful technique to characterize the energy landscape of individual proteins, the mechanical properties of nucleic acids, and the strength of receptor-ligand interactions. Atomic-force-microscopy (AFM)-based SMFS benefits from ongoing progress in improving the precision and stability of cantilevers and the AFM itself. Underappreciated is that the accuracy of such AFM studies remains hindered by inadvertently stretching molecules at an angle while measuring only the vertical component of the force and extension, degrading both measurements...
December 15, 2017: ACS Nano
Akash Gupta, Riddha Das, Gulen Yesilbag Tonga, Tsukasa Mizuhara, Vincent M Rotello
Early detection of biofilms is crucial for limiting infection-based damage. Imaging these biofilms is challenging: conventional imaging agents are unable to penetrate the dense matrix of the biofilm, and many imaging agents are susceptible to false positive/negative responses due to phenotypical mutations of the constituent microbes. We report the creation of pH-responsive nanoparticles with embedded transition metal catalysts (nanozymes) that effectively target the acidic microenvironment of biofilms. These pH-switchable nanozymes generate imaging agents through bio-orthogonal activation of pro-fluorophores inside biofilms...
December 15, 2017: ACS Nano
Stefan Braun, Šárka Pokorná, Radek Šachl, Martin Hof, Heiko Heerklotz, Maria Hoernke
The mode of action of membrane-active molecules such as antimicrobial, anticancer, cell penetrating, and fusion peptides and their synthetic mimics, transfection agents and drug permeation enhancers, biological signaling molecules (e.g., quorum sensing), involves either the general or local destabilization of the target membrane or the formation of defined, rather stable pores. Some effects aim at killing the cell, others need to be limited in space and time to avoid serious damage. Biological tests reveal translocation of compounds and cell death but do not provide a detailed, mechanistic, and quantitative understanding of the modes of action and their molecular basis...
December 15, 2017: ACS Nano
Wei Liu, Mani Ulaganathan, Ibrahim Abdelwahab, Xin Luo, Zhongxin Chen, Sherman Jun Rong Tan, Xiaowei Wang, Yanpeng Liu, Dechao Geng, Yang Bao, Jianyi Chen, Kian Ping Loh
Two-dimensional (2-D) polymer has properties that are attractive for energy storage applications because of its combination of heteroatoms, porosities and layered structure, which provides redox chemistry and ion diffusion routes through the 2-D planes and 1-D channels. Here, conjugated aromatic polymers (CAPs) were synthesized in quantitative yield via solid-state polymerization of phenazine-based precursor crystals. By choosing flat molecules (2-TBTBP and 3-TBQP) with different positions of bromine substituents on a phenazine-derived scaffold, C-C cross coupling was induced following thermal debromination...
December 15, 2017: ACS Nano
Jie Chen, Honglin Luo, Yan Liu, Wei Zhang, Hongxue Li, Tao Luo, Kun Zhang, Yongxiang Zhao, Junjie Liu
Hypoxia as one characteristic hallmark of solid tumors has been demonstrated to be involved in cancer metastasis and progression, induce severe resistance to oxygen-dependent therapies, and hamper the transportation of theranostic agents. To address these issues, an oxygen-self-produced sonodynamic therapy (SDT) nanoplatform involving a modified fluorocarbon (FC)-chain-mediated oxygen delivery protocol has been established to realize highly efficient SDT against hypoxic pancreatic cancer. In this nanoplatform, mesopores and FC chains of FC-chain-functionalized hollow mesoporous organosilica nanoparticle carriers can provide sufficient storage capacity and binding sites for sonosensitizers (IR780) and oxygen, respectively...
December 15, 2017: ACS Nano
Aditya Kulkarni, Wiel H Evers, Stanko Tomic, Matthew C Beard, Daniël Vanmaekelbergh, Laurens D A Siebbeles
Carrier multiplication (CM) is a process in which a single photon excites two or more electrons. CM is of interest to enhance the efficiency of a solar cell. Until now, CM in thin films and solar cells of semiconductor nanocrystals (NCs) has been found at photon energies well above the minimum required energy of twice the band gap. The high threshold of CM strongly limits the benefits for solar cell applications. We show that CM is more efficient in a percolative network of directly connected PbSe NCs. The CM threshold is at twice the band gap and increases in a step-like fashion with photon energy...
December 14, 2017: ACS Nano
Swatantra Pratap Singh, Yilun Li, Jibo Zhang, James M Tour, Christopher J Arnusch
Graphene based materials have profoundly impacted research in nanotechnology and this has significantly advanced biomedical, electronics, energy, and environmental applications. Laser-induced graphene (LIG) is made photothermally and has enabled a rapid route for graphene layers on polyimide surfaces. However, polysulfone (PSU), polyethersulfone (PES), and polyphenylsulfone (PPSU) are highly used in numerous applications including medical, energy and water treatment and they are critical components of polymer membranes...
December 14, 2017: ACS Nano
En-Li Lin, Wei-Lun Hsu, Yeo-Wan Chiang
In theory, gyroid photonic crystals in butterfly wings exhibit advanced optical properties as a result of their highly interconnected microstructures. Because of the difficulties in synthesizing artificial gyroid materials having periodicity corresponding to visible wavelengths, human-made visible gyroid photonic crystals are still unachievable by self-assembly. In this study, we develop a physical approach-trapping of structural coloration (TOSC)-through which the visible structural coloration of an expanded gyroid lattice in a solvated state can be preserved in the solid state, thereby allowing the fabrication of visible-wavelength gyroid photonic crystals...
December 14, 2017: ACS Nano
Qian Wu, Li-Xiu Gong, Yang Li, Cheng-Fei Cao, Long-Cheng Tang, Lianbin Wu, Li Zhao, Guo-Dong Zhang, Shi-Neng Li, Jiefeng Gao, Yongjin Li, Yiu-Wing Mai
Design and development of smart sensors for rapid flame detection in post-combustion and early fire warning in pre-combustion situations are critically needed to improve the fire safety of combustible materials in many applications. Herein, we describe the fabrication of hierarchical coatings created by assembling a multi-layered graphene oxide (GO)/silicone structure onto different combustible substrate materials. The resulting coatings exhibit distinct temperature-response electrical resistance change as efficient early-warning sensors for detecting abnormal high environmental temperature, thus enabling fire prevention below the ignition temperature of combustible materials...
December 14, 2017: ACS Nano
Zonglin Gu, Leigh D Plant, Xuanyu Meng, Jose Manuel Perez-Aguilar, Zegao Wang, Mingdong Dong, Diomedes E Logothetis, Ruhong Zhou
Molybdenum disulfide (MoS2) nanomaterial has recently found various applications in the biomedical field mainly due to its outstanding physicochemical properties. However, little is known about its interactions with biological systems at the atomic level, which intimately relates to the biocompatibility of the material. To provide insights into the effects of MoS2 in biological entities, we investigated the interactions of MoS2 with proteins from a functionally important membrane family, the ubiquitous potassium (K+) channels...
December 13, 2017: ACS Nano
Anh T Ngo, Timur Skeini, Violeta Iancu, Paul C Redfern, Larry A Curtiss, Saw Wai Hla
Carotenoids and chlorophyll are essential parts of plant leaves and are involved in photosynthesis; a vital biological process responsible for the origin of life on Earth. Here, we investigate how β-carotene and chlorophyll-a form mixed molecular phases on a Au(111) surface using low temperature scanning tunneling microscopy and molecular manipulation at the single molecule level supported by density functional theory calculations. By isolating individual molecules from nanoscale molecular clusters with a scanning tunneling microscope tip, we are able to identify five β-carotene conformations including a structure exhibiting a 3-dimensional conformation...
December 13, 2017: ACS Nano
Qi Zhang, Fumiaki Matsuoka, Hyo Seon Suh, Peter A Beaucage, Shisheng Xiong, Detlef-M Smilgies, Kwan Wee Tan, Jörg G Werner, Paul F Nealey, Ulrich B Wiesner
Three-dimensional (3D) mesoporous thin films with sub-100 nm periodic lattices are of increasing interest as templates for a number of nanotechnology applications yet are hard to achieve with conventional top-down fabrication methods. Block copolymer self-assembly derived mesoscale structures provide a toolbox for such 3D template formation. In this work, single (alternating) gyroidal and double gyroidal mesoporous thin film structures are achieved via solvent vapor annealing assisted co-assembly of poly(isoprene-block-styrene-block-ethylene oxide) (PI-b-PS-b-PEO, ISO) and resorcinol/phenol formaldehyde resols...
December 13, 2017: ACS Nano
Luis Ruiz Pestana, Lisa E Felberg, Teresa Head-Gordon
Flexible nanoscale confinement is critical to understanding the role that bending fluctuations play on biological processes where soft interfaces are ubiquitous, or to exploit confinement effects in engineered systems where inherently flexible 2D materials are pervasively employed. Here, using molecular dynamics simulations, we compare the phase behavior of water confined between flexible and rigid graphene sheets as a function of the in-plane density, ρ_2D. We find that both cases show commensurate mono-, bi-, and tri-layered states, however the water phase in those states and the transitions between them are qualitatively different for the rigid and flexible cases...
December 13, 2017: ACS Nano
Kyu-Man Hwang, Jun-Young Park, Hagyoul Bae, Seung-Wook Lee, Choong-Ki Kim, Myungsoo Seo, Hwon Im, Do-Hyun Kim, Seong-Yeon Kim, Geon-Beom Lee, Yang-Kyu Choi
A physical unclonable function (PUF) device using a nano-electromechanical (NEM) switch was demonstrated. The most important feature of the NEM-switch-based PUF is its use of stiction. Stiction is one of the chronic problems associated with micro- and nano-electromechanical system (MEMS/NEMS) devices; however, here, it was utilized to intentionally implement a PUF for hardware-based security. The stiction is caused by capillary and van der Waals forces, producing strong adhesion, which can be utilized to design a highly robust and stable PUF...
December 13, 2017: ACS Nano
Xingshu Li, Sungsook Yu, Dayoung Lee, Gyoungmi Kim, Buhyun Lee, Yejin Cho, Bi-Yuan Zheng, Mei-Rong Ke, Jian-Dong Huang, Ki Taek Nam, Xiaoyuan Chen, Juyoung Yoon
Supramolecular chemistry provides a "bottom-up" method to fabricate nanostructures for biomedical applications. Herein, we report a facile strategy to directly assemble a phthalocyanine photosensitizer (PcS) with an anticancer drug mitoxantrone (MA) to form uniform nanostructures (PcS-MA), which not only display nanoscale optical properties but also have the capability of undergoing nucleic acid-responsive disassembly. These supramolecular assemblies possess activatable fluorescence emission and singlet oxygen generation associated with the formation of free PcS, mild photothermal heating, and a concomitant chemotherapeutic effect associated with the formation of free MA...
December 12, 2017: ACS Nano
Dominic W Malcolm, Jomy J Varghese, Janet E Sorrells, Catherine E Ovitt, Danielle S W Benoit
Nanoparticles (NP) interact with complex protein milieus in biological fluids, and these interactions have profound effects on NP physicochemical properties and function. Surprisingly, most studies neglect the impact of these interactions, especially with respect to NP-mediated siRNA delivery. Here, the effects of serum on colloidal stability and siRNA delivery of a pH-responsive micellar NP delivery system were characterized. Results show cationic NP-siRNA complexes aggregate in  2% serum in buffer, but are stable in serum-free media...
December 12, 2017: ACS Nano
Li-Juan Zhang, Li Xia, Shu-Lin Liu, En-Ze Sun, Qiu-Mei Wu, Li Wen, Zhi-Ling Zhang, Dai-Wen Pang
When infecting host cells, influenza virus must move on microfilaments (MFs) at the cell periphery and then move along microtubules (MTs) through the cytosol to reach the perinuclear region for genome release. But how viruses switch from the actin roadway to the microtubule highway remains obscure. To settle this issue, we systematically dissected the role of related motor proteins in the transport of influenza virus between cytoskeletal filaments in situ and in real-time using quantum dot (QD)-based single-virus tracking (SVT) and multicolor imaging...
December 12, 2017: ACS Nano
Cheng Jin, Xiaojing Liu, Huarong Bai, Ruowen Wang, Jie Tan, Xuehui Peng, Weihong Tan
Because of their facile preparation, small size (<100 nm), programmable design and biocompatibility, lipid-based DNA micelles show enormous potential as a tool to monitor biological events and treat human diseases. However, their structural stability in biological matrices suffers from spatiotemporal variability, thus limiting their in vivo use. Herein, we have engineered stability-tunable DNA micelleflares using photocontrollable dissociation of intermolecular G-quadruplexes, which confers DNA micelleflares with robust structural stability against disruption by serum albumin...
December 12, 2017: ACS Nano
Jingjing Chen, Zhiyong Mao, Lexi Zhang, Dajian Wang, Ran Xu, Lijian Bie, Bradley D Fahlman
Graphitic carbon nitride (g-C3N4) behaving as a layered feature with graphite was indexed as a high-content nitrogen-doping carbon material, attracting increasing attention for application in energy storage devices. However, poor conductivity and resulting serious irreversible capacity loss were pronounced for g-C3N4 material due to its high nitrogen content. In this work, magnesiothermic denitriding technology is demonstrated to reduce the nitrogen content of g-C3N4 (especially graphitic nitrogen) for enhanced lithium storage properties as lithium ion battery anodes...
December 12, 2017: ACS Nano
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