Towards single biomolecule handling and characterization by MEMS

Damage-less Handling of Exosomes Using an Ion-depletion Zone in a Microchannel

Exosomes are of increasing research interest because they are integral to cell-cell communication and are implicated in various disease states. Here, we investigated the utility of using an ion-depletion zone in a microfluidic device to concentrate exosomes from the culture media of four types of cell lines. Furthermore, we evaluated the extent of damage to the exosomes following concentration by an ion-depletion zone microchannel device compared with exosomes concentrated by a conventional ultra-centrifugation technique. Our results conclusively demonstrate that significantly less damage is incurred by exosomes following passage through and concentration by the ion-depleted zone microchannel device compared to concentration by ultra-centrifugation. Our findings will help extend the utility of exosomes to various applications.

A Novel Fabrication Technique for Liquid-Tight Microchannels by Combination of a Paraffin Polymer and a Photo-Curable Silicone Elastomer

The development and growth of microfluidics has been mainly based on various novel fabrication techniques for downsizing and integration of the micro/nano components. Especially, an effective fabrication technique of three-dimensional structures still continues to be strongly required in order to improve device performance, functionality, and device packing density because the conventional lamination-based technique for integrating several two-dimensional components is not enough to satisfy the requirement. Although three-dimensional printers have a high potential for becoming an effective tool to fabricate a three-dimensional microstructure, a leak caused by the roughness of a low-precision structure made by a 3D printer is a critical problem when the microfluidic device is composed of several parts. To build a liquid-tight microchannel on such a low-precision structure, we developed a novel assembly technique in which a paraffin polymer was used as a mold for a microchannel of photo-curable silicone elastomer on a rough surface. The shape and roughness of the molded microchannel was in good agreement with the master pattern. Additionally, the seal performance of the microchannel was demonstrated by an experiment of electrophoresis in the microchannel built on a substrate which has a huge roughness and a joint.

Nanometer-level high-accuracy molding using a photo-curable silicone elastomer by suppressing thermal shrinkage

The photocured elastomer presented here provided extremely high replication accuracy due to its thermal shrinkage of less than 0.02%, compared to 2.91% in the heat-cured elastomer.

Microfluidics in macro-biomolecules analysis: macro inside in a nano world

Use of microfluidic devices in the life sciences and medicine has created the possibility of performing investigations at the molecular level. Moreover, microfluidic devices are also part of the technological framework that has enabled a new type of scientific information to be revealed, i.e. that based on intensive screening of complete sets of gene and protein sequences. A deeper bioanalytical perspective may provide quantitative and qualitative tools, enabling study of various diseases and, eventually, may offer support for the development of accurate and reliable methods for clinical assessment. This would open the way to molecule-based diagnostics, i.e. establish accurate diagnosis and disease prognosis based on identification and/or quantification of biomacromolecules, for example proteins or nucleic acids. Finally, the development of disposable and portable devices for molecule-based diagnosis would provide the perfect translation of the science behind life-science research into practical applications dedicated to patients and health practitioners. This review provides an analytical perspective of the impact of microfluidics on the detection and characterization of bio-macromolecules involved in pathological processes. The main features of molecule-based diagnostics and the specific requirements for the diagnostic devices are discussed. Further, the techniques currently used for testing bio-macromolecules for potential diagnostic purposes are identified, emphasizing the newest developments. Subsequently, the challenges of this type of application and the status of commercially available devices are highlighted, and future trends are noted.

Miniaturized thermocontrol devices enable analysis of biomolecular behavior on their timescales, second to millisecond

To establish general-purpose methods and tools for biological experiments on a short time scale is an essential requirement for future research in molecular biology because most of the functions of living organisms at the molecular level take place on a time scale from 1-second to millisecond. Thermal control with on-chip micro-thermodevices is one of the strongest and most useful ways to realize biological experiments at molecular level on these time scales. Novel biological phenomena revealed by the experiments using micro-thermodevices on a 1-second and millisecond time scale will be shown for the proof. Finally, the advantages and impact of this methodology in molecular biology will be discussed.