Rapid,High‐Throughput,and Direct Molecular Beacon Delivery to Human Cancer Cells Using a Nanowire‐Incorporated and Pneumatic Pressure‐Driven Microdevice

Tracking and monitoring the intracellular behavior of mRNA is of paramount importance for understanding real‐time gene expression in cell biology. To detect specific mRNA sequences, molecular beacons (MBs) have been widely employed as sensing probes. Although numerous strategies for MB delivery into the target cells have been reported, many issues such as the cytotoxicity of the carriers, dependence on the random probability of MB transfer, and critical cellular damage still need to be overcome. Herein, we have developed a nanowire‐incorporated and pneumatic pressure‐driven microdevice for rapid, high‐throughput, and direct MB delivery to human breast cancer MCF‐7 cells to monitor survivin mRNA expression. The proposed microdevice is composed of three layers: a pump‐associated glass manifold layer, a monolithic polydimethylsiloxane (PDMS) membrane, and a ZnO nanowire‐patterned microchannel layer. The MB is immobilized on the ZnO nanowires by disulfide bonding, and the glass manifold and PDMS membrane serve as a microvalve, so that the cellular attachment and detachment on the MB‐coated nanowire array can be manipulated. The combination of the nanowire‐mediated MB delivery and the microvalve function enable the transfer of MB into the cells in a controllable way with high cell viability and to detect survivin mRNA expression quantitatively after docetaxel treatment.     

Fabrication of Reproducible,Integration‐Compatible Hybrid Molecular/Si Electronics

Reproducible molecular junctions can be integrated within standard CMOS technology. Metal–molecule–semiconductor junctions are fabricated by direct Si–C binding of hexadecane or methyl‐styrene onto oxide‐free H‐Si(111) surfaces, with the lateral size of the junctions defined by an etched SiO₂ well and with evaporated Pb as the top contact. The current density, J, is highly reproducible with a standard deviation in log(J) of 0.2 over a junction diameter change from 3 to 100 μm. Reproducibility over such a large range indicates that transport is truly across the molecules and does not result from artifacts like edge effects or defects in the molecular monolayer. Device fabrication is tested for two n‐Si doping levels. With highly doped Si, transport is dominated by tunneling and reveals sharp conductance onsets at room temperature. Using the temperature dependence of current across medium‐doped n‐Si, the molecular tunneling barrier can be separated from the Si‐Schottky one, which is a 0.47 eV, in agreement with the molecular‐modified surface dipole and quite different from the bare Si–H junction. This indicates that Pb evaporation does not cause significant chemical changes to the molecules. The ability to manufacture reliable devices constitutes important progress toward possible future hybrid Si‐based molecular electronics.     

H/F‐Substitution‐Induced Homochirality for Designing High‐Tc Molecular Perovskite Ferroelectrics

A ferroelectric with a high phase‐transition temperature (T_c) is an indispensable condition for practical applications. Over the past decades, both strain engineering and the isotope effect have been found to effectively improve the T_c within ferroelectric material systems. However, the former strategy seems to prefer working in inorganic ferroelectric thin films, while the latter is also limited to some certain systems, such as hydrogen‐bonded ferroelectrics. It is noted that a mono‐fluorinated molecule is geometrically very similar to its parent molecule and the substitution of H by an F atom can introduce a chiral center on the molecule to template or stabilize polar structures. Significantly, the barrier of rotation of the fluorinated organic molecules is raised, resulting in a remarkable increase in T_c. Herein, by applying the molecular design strategy of H/F substitution to the organic–inorganic perovskite ferroelectric (pyrrolidinium)CdCl₃ with a low T_c of 240 K, two high‐T_c chiral perovskite ferroelectrics, (R)‐ and (S)‐3‐F‐(pyrrolidinium)CdCl₃ are successfully synthesized, for which the T_c reaches 303 K. The significant enhancement of 63 K in T_c extends the ferroelectric working temperature range to room temperature. This finding provides a new effective way to regulate the T_c in ferroelectrics and to design high‐T_c molecular ferroelectrics.     

Molecular Lubricants and Glues for Micro‐ and Nanodevices

Research advances in molecular coatings from functional polymeric and organic molecules designed as molecular lubricants or molecular glues for micro‐ and nanodevices are presented here, with a focus on organized molecular films from amphiphilic molecules, molecules with reactive ends and functional oligomers. The interfacial properties of molecular coatings critical for their lubrication (see Figure) or adhesive performance at the nanoscale are discussed in conjunction with results on molecular structure and morphology of these coatings. Examples of the latest developments in the field of nanocomposite molecular coatings and applications of molecular lubrication concepts for computer hard drives are presented.     

Molecular dynamics‐smoothed molecular dynamics (MD‐SMD) adaptive coupling method with seamless transition

Smoothed molecular dynamics (SMD) method is a recently proposed efficient molecular simulation method by introducing one set of background mesh and mapping process into molecular dynamics (MD) flow chart. SMD can sharply enlarge MD time step size while maintaining global accuracy. MD‐SMD coupling method was proposed to improve the capability to describe local atom disorders. The coupling method is greatly improved in this paper in two essential aspects. Firstly, a transition scheme is proposed to avoid artificial wave reflection at the interface of MD and SMD regions. The new transition scheme has simple formulation and high efficiency, and the wave reflection can be well suppressed. Secondly, an adaptive scheme is proposed to automatically identify the regions requiring MD simulation. Two adaptive criteria, the centro‐symmetry parameter criterion and the displacement criterion, are also proposed. It is found that both the two criteria can achieve good accuracy but the efficiency of the displacement criterion is much better. The coupling method does not demand reduction in mesh size near the interface, and a multiple time stepping scheme is adopted to ensure high efficiency. Numerical results including wave propagation, nano‐indentation, and crack propagation validate the method and show nice accuracy. Copyright © 2016 John Wiley & Sons, Ltd.     

High‐Performance Additive‐/Post‐Treatment‐Free Nonfullerene Polymer Solar Cells via Tuning Molecular Weight of Conjugated Polymers

In recent years, rapid advances are achieved in polymer solar cells (PSCs) using nonfullerene small molecular acceptors. However, no research disclosing the influence of molecular weight (M_n) of conjugated polymer on the nonfullerene device performance is reported. In this work, a series of polymers with different M_ns are synthesized to systematically investigate the connection between M_n and performance of nonfullerene devices for the first time. It is found that the device performance improves substantially as the M_n increases from 12 to 38 kDa and a power conversion efficiency (PCE) as high as 10.5% is realized. It has to be noted this PCE is achieved without using any additives and post‐treatments, which is among the top efficiencies of additive‐ and post‐treatment‐free PSCs. Most importantly, the variation trend of the optimal active layer thickness and morphology is significantly different from the device with fullerene as acceptor. The findings clarify the effect of M_n on the performance of nonfullerene PSCs, which would benefit further efficiency improvement of nonfullerene PSCs.     

Rotating‐Electric‐Field‐Induced Carbon‐Nanotube‐Based Nanomotor in Water: A Molecular Dynamics Study

Using molecular dynamics simulations, it is shown that a carbon nanotube (CNT) suspended in water and subjected to a rotating electric field of proper magnitude and angular speed can be rotated with the aid of water dipole orientations. Based on this principle, a rotational nanomotor structure is designed and the system is simulated in water. Use of the fast responsiveness of electric‐field‐induced CNT orientation in water is employed and its operation at ultrahigh‐speed (over 10¹¹ r.p.m.) is shown. To explain the basic mechanism, the behavior of the rotational actuation, originated from the water dipole orientation, is also analyzed . The proposed nanomotor is capable of rotating an attached load (such as CNT) at a precise angle as well as nanogear‐based complex structures. The findings suggest a potential way of using the electric‐field‐induced CNT rotation in polarizable fluids as a novel tool to operate nanodevices and systems.     

3D NIR‐II Molecular Imaging Distinguishes Targeted Organs with High‐Performance NIR‐II Bioconjugates

Greatly reduced scattering in the second near‐infrared (NIR‐II) region (1000–1700 nm) opens up many new exciting avenues of bioimaging research, yet NIR‐II fluorescence imaging is mostly implemented by using nontargeted fluorophores or wide‐field imaging setups, limiting the signal‐to‐background ratio and imaging penetration depth due to poor specific binding and out‐of‐focus signals. A newly developed high‐performance NIR‐II bioconjugate enables targeted imaging of a specific organ in the living body with high quality. Combined with a home‐built NIR‐II confocal set‐up, the enhanced imaging technique allows 900 µm‐deep 3D organ imaging without tissue clearing techniques. Bioconjugation of two hormones to nonoverlapping NIR‐II fluorophores facilitates two‐color imaging of different receptors, demonstrating unprecedented multicolor live molecular imaging across the NIR‐II window. This deep tissue imaging of specific receptors in live animals allows development of noninvasive molecular imaging of multifarious models of normal and neoplastic organs in vivo, beyond the traditional visible to NIR‐I range. The developed NIR‐II fluorescence microscopy will become a powerful imaging technique for deep tissue imaging without any physical sectioning or clearing treatment of the tissue.