Meng Wang

Determining intracellular temperature at single-cell level by a novel thermocouple method.

Living cells can change their intramembranous temperature during cell activities such as division, gene expression, enzyme reaction, and metabolism [1, 2]. Moreover, under external stimuli, such as drugs or other signals, cells may quickly change their metabolic activities, leading to acute variation of intracellular temperatures from the normal state [3, 4]. However, such temperature change inside cells is usually at a small scale and is of transient nature due to the thermo-influence by the extracellular environment, rendering it rather difficult to measure using the conventional temperature detection methods. Thus, a more precise and faster-response thermometer is needed to measure single-cell temperature changes in real time, which may constitute a new layer of cellular information for studies of cellular signaling, and even clinical diagnosis and therapy. Fluorescent nanogel has been previously applied to detect changes in intracellular temperature [4]. Cells were first allowed to take up a fluorescence material and the average intracellular temperature change under a certain treatment was then determined through measuring the distinct fluorescent light intensity before and after the treatment. Such a fluorescent nanogel-based method has a number of disadvantages, including potential toxicity to cells, limit of measurement resolution (generally in the range of 0.29 °C-0.50 °C), and limit of time-scale resolution (at the scale of minutes). Thermocouple (TC) is widely used in settings that require detection of temperature changes. The TC-based detection method has a number of advantages, including the capacity for achieving high precision and rapid response. To adapt the TC method for temperature measurement at the single-cell level, one would need to develop a micro-sized TC probe (at sub-micrometer scale). The thin film method is a common approach to producing two-dimensional microor even nano-TCs for use in electronics industry [5]. However, such two-dimensional TCs that rely on the support of silicon chips cannot be readily used for measuring intracellular temperature. In npg Cell Research (2011) 21:1517-1519.

Magnetically Enhanced Dielectrophoretic Assembly of Horseradish Peroxidase Molecules: Chaining and Molecular Monolayers

Recently, interest in the controlled assembly of colloids has increased due to its scientific importance and widespread applications in nanoscience and nanotechnology. Electric and magnetic fields are common tools to direct the self-assembly process under which nanoparticles often form one-dimensional ensembles. Resulting from high-order damping with particulate size, the electromagnetic force is traditionally considered too weak to assemble very small objects. Although there are recent reports on electromagnetically controlled colloidal aggregation, showing the possibility that an electromagnetic field can manipulate nanoparticle aggregates, the electromagnetically mediated assembly of several-nanometres-sized biological macromolecules has remained unexplored. This is mainly due to the small size of biological molecules and the possible destructive effect caused by planar lithographic electrodes. However, there are at least two driving forces in studying the field-controlled assembly of biological macromolecules. Firstly, proteins are greatly involved in many problems concerning life and health. Thus, the controlled assembly of proteins may well play an important role in fundamental research and clinical therapy. Secondly, biological macromolecules are also considered as promising components and elementary frameworks in next-generation bioelectronics and devices. The controllable assembly of biological macromolecules may be employed as a fabrication method of these components. Herein, we show a novel experimental design to assemble horseradish peroxidase (HRP) molecules without using lithographical electrodes. Our design is able to generate a magnetostatic field and an alternating electric field simultaneously. The HRP molecules form linear assemblies in the synergistic presence of the magnetostatic and alternating electric fields. More interestingly, the enzyme molecules aggregate into a molecular monolayer on the substrate and their catalytic activity is scarcely deactivated after electromagnetic treatment. Our results demonstrate that the electromagnetic force is also capable of manipulating biological objects smaller than 10 nm without deactivation of biological function. An alternating electric field was extensively employed in colloidal assembly, often called dielectrophoresis. The dielectrophoretic force can be expressed by Equation (1):

Efficient charge pump by pure mechanical resonators in graphene

Graphene is an ideal two-dimensional nanoelectromechanical material due to its outstanding elastic properties and superior electro-mechanical coupling. We study a graphene-based charge pump by two mechanical resonators out of phase. It is found that in the adiabatic limit, the pumped charge per mode is quantized in a pumping cycle and the electro-mechanical conversion efficiency is maximally saturated, as long as the mechanical lattice deformations produce a transport gap for massless Dirac electrons. The efficient charge pump originates from the definite chirality of Dirac electrons as well as the possible topological interface state forming in the evanescent modes. Our findings might shed light on enhancing the electro-mechanical conversion efficiency of graphene-based devices.

Study of fabricating functional nanostructure through combined with molecular assembly

In any way, it is difficult to fabricate a functional nanostructure, especially for the research and development of devices. Arranging atoms, molecules to establish a device structure, named the way of bottom-up, represents a direction along which might be with the advantages of low-cost, easy to control and flexible for forming the structure. At present molecular assembly has been found the very important role in the way of bottom-up. The combination of molecular assembly and other fabrication techniques, e.g., lithography, is the first stage of the bottom-up to fabricate the functional structures of devices. Herein we present our efforts to make the electrodes with the feature of nanogap, the preliminary results of the arrangement of nanoparticles within the gap of the electrodes and the assembly of biomolecules on the surface of the electrode.