Reviews in Molecular Biotechnology最新文献

In this paper, we describe the fabrication technologies necessary for the production of polymer-based micro-fluidic devices. These technologies include hot embossing as a micro-structuring method as well as so-called back-end processes to complete the micro-devices. Applications such as capillary electrophoresis, micro-mixers and nanowell plates are presented.

Miniaturization has grown to be a driving force in modern chemical and biochemical laboratories. Combinatorial explosion demands for new pathways for the synthesis and screening of new substances which can act as leads in drug discovery. Highly parallelized automata that can handle the smallest amounts of substances are needed. However, the development is not always straightforward since new problems also arise in miniaturization, e.g. increasing importance of surface properties of utilized devices and evaporation of liquids. This paper reports on recent developments on the field of miniaturized reaction vessels called nanotiterplates. A survey on fabrication technologies as well as applications of nanotiterplates is given. Special emphasis is given to results of the development of an automaton for miniaturized synthesis and screening. Besides the mere fabrication of nanotiterplates with integrated microsieve bottom membranes, examples of applications in chemical synthesis and bio-assays are given. Further topics are the characterization and specific adaption of surface properties and investigations on the evaporation of solvents and measures for prevention.

In this review we describe aspects of interactions between bioreactors and analytical systems including microsystems. Principles of bioprocess monitoring are summarized, before we focus on the miniaturization of sampling systems guaranteeing bioprocess sterility and providing analytical systems with a liquid sample. The application of negative dielectrophoresis as a new principle for cell retention in a sampling system is described followed by theoretical aspects and results. Properties of micromachined silicon membranes as filters for sampling systems and for biosensor protection are discussed.

The miniaturization of analytical devices by micromachining technology is destined to have a major impact on medical and bioanalytical fields. To meet the current demands for rapid DNA amplification, various instruments and innovative technologies have been introduced by several groups in recent years. The development of the devices was extended in different directions and adapted to corresponding applications. In this review the development of a variety of devices and components for performing DNA amplification as well as the comparison of batch-process thermocyclers with reaction chambers and flow-through devices for different purposes are discussed. The main attention is turned to a flow device concept for thermocycling using microfabricated elements for local heat flow management, for which simulations and considerations for further improvement regarding design, material choice and applied technology were performed. The present review article mainly discusses and compares thermocycling devices for rapid thermocycling made of silicon or of silicon and glass with a short excursion to the possibility of plastic chip devices. In order to perform polymerase chain reactions (PCRs) in the microreactors, special attention must be paid to the conditions of the internal surfaces. For microchips, surface effects are generally pronounced because the surface to volume ratio increases upon miniaturization. Solutions for solving this problem are presented. We propose an overview of layouts for batch-process thermocyclers with different parallelization of reaction chambers and also of different designs of continuous flow thermocycling chips, paying particular attention to the parameters which influence the efficiency of such chip devices. Finally we point out some recent issues for applications in the field of clinical diagnostics.

The investigation of bio-molecules has entered a new age since the development of methodologies capable of studies at the level of single molecules. In biology, most molecules show a complex dynamical behavior, with individual motions and transitions between different states, occurring as highly correlated in space and time within an arrangement of various elements. In order to resolve such dynamical changes in ensemble average techniques, one would have to synchronize all molecules, which is hard to achieve and might interfere with important system properties. Single molecule studies, in contrast, do not require pretreatment of the system and resume, therefore, much less invasive methodologies. Here, we review recent employments for the investigation of bio-molecules on surfaces, in which the high local and temporal resolution of two complementary techniques, atomic force microscopy and single molecule fluorescence microscopy, is used to address single molecules. Novel methodologies for the characterization of biologically relevant parameters, functions and dynamical aspects of individual molecules are described.

Active transport in cells, utilizing molecular motors like kinesin and myosin, provides the inspiration for the integration of active transport into synthetic devices. Hybrid devices, employing motor proteins in a synthetic environment, are the first prototypes of molecular shuttles. Here the basic characteristics of motor proteins are discussed from an engineering point of view, and the experiments aimed at incorporating motor proteins, such as myosins and kinesins, into devices are reviewed. The key problems for the construction of a molecular shuttle are: guiding the direction of motion, controlling the speed, and loading and unloading of cargo. Various techniques, relying on surface topography and chemistry as well as flow fields and electric fields, have been developed to guide the movement of molecular shuttles on surfaces. The control of ATP concentration, acting as a fuel supply, can serve as a means to control the speed of movement. The loading process requires the coupling of cargo to the shuttle, ideally by a strong and specific link. Applications of molecular shuttles can be envisioned, e.g. in the field of nano-electro-mechanical systems (NEMS), where scaling laws favor active transport over fluid flow, and in the bottom-up assembly of novel materials.

The study of single molecules opens a new dimension in understanding nature down to its finest ramifications. While much progress was achieved in the last decade concerning the detection techniques, suitable techniques for manipulating and handling the biomolecules still bear a challenge. Primarily, the task is keeping an individual, active molecule of a certain lifespan in the spot. Here, we will focus on techniques for the functional immobilization of (single) molecules on surfaces to enable their observation at one position over a time period. Presenting the main methods of reversible immobilization we will accentuate the chelator lipid concept as combining all features prerequisite for functional, reversible and well-defined immobilization. This will also show that single molecule research in principle is the synthesis of an insight into the function of nature and nano-biotechnology (manipulation): thus of analytics, construction, and back.

Semi-synthetic conjugates of nucleic acids and proteins can be generated by either covalent coupling chemistry, or else by non-covalent biomolecular recognition systems, such as receptor–ligands of complementary nucleic acids. These nucleic acid–protein conjugates are versatile molecular tools which can be applied, for instance, in the self-assembly of high-affinity reagents for immunological detection assays, the fabrication of laterally microstructured biochips containing functional biological groups, and the biomimetic ‘bottom–up’ synthesis of nanostructured supramolecular devices. This review summarizes the current state-of-the-art synthesis and characterization methods of artificial nucleic acid–protein conjugates, as well as applications and perspectives for future developments of such hybrid biomolecular components in life sciences and nanobiotechnology.