基礎講座 電気泳動(Electrophoresis)

Fundamental and applied research in chemistry and biology benefits from opportunities provided by droplet-based microfluidic systems. These systems enable the miniaturization of reactions by compartmentalizing reactions in droplets of femoliter to microliter volumes. Compartmentalization in droplets provides rapid mixing of reagents, control of the timing of reactions on timescales from milliseconds to months, control of interfacial properties, and the ability to synthesize and transport solid reagents and products. Droplet-based microfluidics can help to enhance and accelerate chemical and biochemical screening, protein crystallization, enzymatic kinetics, and assays. Moreover, the control provided by droplets in microfluidic devices can lead to new scientific methods and insights.

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Reactions in Droplets in Microfluidic Channels

Micro total analysis systems. Latest advancements and trends.

In recent years, tools for the development of new drugs have been dramatically improved. These include genomic and proteomic research, numerous biophysical methods, combinatorial chemistry and screening technologies. In addition, early ADMET studies are employed in order to significantly reduce the failure rate in the development of drug candidates. As a consequence, the lead finding, lead optimization and development process has gained marked enhancement in speed and efficiency. In parallel to this development, major pharma companies are increasingly outsourcing many components of drug discovery research to biotech companies. All these measures are designed to address the need for a faster time to market. New screening methodologies have contributed significantly to the efficiency of the drug discovery process. The conventional screening of single compounds or compound libraries has been dramatically accelerated by high throughput screening methods. In addition, in silico screening methods allow the evaluation of virtual compounds. A wide range of new lead finding and lead optimization opportunities result from novel screening methods by NMR, which are the topic of this review article.

Drug Discovery Today

The field of cantilever-based sensing emerged in the mid-1990s and is today a well-known technology for label-free sensing which holds promise as a technique for cheap, portable, sensitive and highly parallel analysis systems. The research in sensor realization as well as sensor applications has increased significantly over the past 10 years. In this review we will present the basic modes of operation in cantilever-like micromechanical sensors and discuss optical and electrical means for signal transduction. The fundamental processes for realizing miniaturized cantilevers are described with focus on silicon- and polymer-based technologies. Examples of recent sensor applications are given covering such diverse fields as drug discovery, food diagnostics, material characterizations and explosives detection.

http://iopscience.iop.org/article/10.1088/0034-4885/74/3/036101/pdf

Cantilever-like micromechanical sensors

This paper describes a simple method for the microfabrication of mechanically compliant, magnetically-responsive microstructures. These microstructures were fabricated in one step by using a ferromagnetic photoresist, which, in turn, was prepared by suspending nickel nanospheres in a negative photosensitive epoxy (SU8). The nominal diameter of the nickel nanospheres was 80–150 nm, that is, much smaller than the wavelength of the UV light (365 and 405 nm) used to expose the photoresist. Diffraction and scattering of light from the nanospheres allowed for full exposure of the photoresist, even after the incorporation of nanospheres at levels at which it became opaque. The ferromagnetic photoresist was cross-linked after exposure and development, and yielded a stable, compliant, ferromagnetic pattern. The paper characterizes the effect of the weight density of the nickel nanospheres on the transmittance of films made by this technique at wavelengths from 330 nm to 610 nm. It also describes a number of microstructures made with the photoresist: examples include lines, posts and meshes. As a demonstration, the procedure was applied to the microfabrication of a set of magnetically-actuated micromirrors. These micromirrors achieved large deflections: deflection at the tip of a 12 mm long, 250 µ mw ide and 70 µm thick cantilever of the ferromagnetic photoresist exceeded 1.4 mm, when actuated by a NbFeB permanent magnet with field strength ∼120 mT. The cantilever maintained its mechanical properties after cycling ∼10 6 times. S This article has online supplementary material

https://iopscience.iop.org/article/10.1088/0960-1317/15/1/005/pdf

Composite ferromagnetic photoresist for the fabrication of microelectromechanical systems

This work describes a simple optical method for obtaining, in a single still-capture image, the continuous absorbance spectra of samples at multiple locations of microsystems. This technique uses an unmodified bright-field microscope, an array of microlenses, and a diffraction grating to disperse the light transmitted by samples of 10- to 500-μm dimensions. By analyzing in a single image the first-order diffracted light, it is possible to collect the full and continuous absorbance spectra of samples at multiple locations (to a spatial resolution of ≈8 μm) in microwells and microchannels to examine dynamic chemical events (to a time resolution of <10 ms). This article also discusses the optical basis of this method. The simultaneous resolution of wavelength, time, and space at a scale <10 μm provides additional capabilities for chemical and biological analysis.

https://www.pnas.org/content/pnas/102/29/10035.full.pdf

Nicolae Damean

Papers

Composite ferromagnetic photoresist for the fabrication of microelectromechanical systems

Space- and time-resolved spectrophotometry in microsystems