Protein chips fabrication

Camarero JA, Kwon Y, Coleman MA. Chemoselective attachment of biologically active proteins to surfaces by expressed protein Ugation and its appUcation for protein chip fabrication. J. Am. Chem. Soc. 2004 126(45) 14730-14731. 

K.Y. Park, M.S. Kim, and S.Y. Choi, Fabrication and characteristics of MOSFET protein chip for detection of ribosomal protein. Biosens. Bioelectron. 20, 2111-2115 (2005). 

Other early work includes that of Moody et al. (2001) who spotted anticytokine monoclonals onto the bottom of polystyrene microtiter plates (Max-isorp, Nalge Nunc) and measured cytokine levels in stimulated peripheral blood mononuclear cells. Finally, although not strictly a microarray, the microwell array system developed by Michael Snyder s group at Yale University to measure kinase activity is a simple and elegant approach (Zhu et al., 2000). The "protein chip" is comprised of microwells fabricated in a flexible elastomer of PDMS [poly(dimethylsiloxane)] substrate by a molding process. 

More recent trends aim in the direction of fabricating electrochemical protein array systems (for detecting multiple protein targets) and miniaturization of such immunoassays. These include an electrochemical protein chip with an array of 36 platinum electrodes on a glass substrate (64) and electrical immunoassays using microcavity formats down to the zmol antigen level (65). 

The application of polymer monoliths in 2D separations, however, is very attractive in that polymer-based packing materials can provide a high performance, chemically stable stationary phase, and better recovery of biological molecules, namely proteins and peptides, even in comparison with C18 phases on silica particles with wide mesopores (Tanaka et al., 1990). Microchip fabrication for 2D HPLC has been disclosed in a recent patent, based on polymer monoliths (Corso et al., 2003). This separation system consists of stacked separation blocks, namely, the first block for ion exchange (strong cation exchange) and the second block for reversed-phase separation. This layered separation chip device also contains an electrospray interface microfabricated on chip (a polymer monolith/... 

In contrast to high density arrays low density arrays are made by deposition of pre-synthesized oligonucleotides or proteins on activated surfaces. There are several printing techniques for fabricating microarrays Non-contact biochip arrayers, commonly based on the piezoelectric effect, can apply controlled sub-nanoliter probe volumes to pre-specified locations on the chip surface. Due to the fact that the dispenser does not touch the surface, a non-contact arrayer provides low risk of contamination and is most suitable for printing on soft materials such as hydrogels. 

A number of different types of ESI sources, known as nanospray sources, have been designed that can operate at lower sample flow rates (10-200 nL min ). These generate smaller droplets and improve the signal intensity of the protein-ligand noncovalent complexes further, with the added benefit of reducing protein consumption up to 100-fold compared to standard ESI flow rates. Nanospray has also been reported to be more tolerant to nonvolatile cations in solution [37]. Recently, an automated fabricated chip nanospray source has been developed. This chip-based device has improved the ease-of-use for nanospray, while the design eliminates carryover effects as the spray is produced directly from an orifice on each sample well of the chip [38]. 

We further addressed the use of the nucleic acids as biopolymers for the formation of supramolecular structures that enable the electronic or electrochemical detection of DNA. Specifically, we discussed the use of aptamer/low-molecular-weight molecules or aptamer/protein supramolecular complexes for the electrical analysis of the guest substrates in these complexes. Also, nucleic acid-NPs hybrid systems hold a great promise as sensing matrices for the electrical detection of DNA in composite three-dimensional assemblies. While sensitive and selective electrochemical sensors for DNA were fabricated, the integration of these sensor configurations in array formats (DNA chips) for the multiplexed analysis of many DNAs can also be envisaged. 

S. Ferko, V. A. VanderNoot, J. A. A. West, R. Crocker, B. Wiedenman, D. Yee, and J. A. Fruetel, Hand-Held Microanalytical Instrument for Chip-Based Electrophoretic Separations of Proteins, Anal. Chem. 2005, 77, 435 J. G. E. Gardeniers and A. van den Berg, Lab-on-a-Chip Systems for Biomedical and Environmental Monitoring, Anal. Bioanal. Chem 2004,378, 1700 J. C. McDonald and G. M. Whitesides, Poly(dimethylsiloxane) as a Material for Fabricating Microfluidic Devices, Acc. Chem. Res. 2002,35, 491 Y. Huang,... 

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