A 2-D microcantilever array for multiplexed biomolecular analysis

An accurate, rapid, and quantitative method for analyzing variety of biomolecules, such as DNA and proteins, is necessary in many biomedical applications and could help address several scientific issues in molecular biology. Recent experiments have shown that when specific biological reactions occur on one surface of a microcantilever beam, the resulting changes in surface stress deflect the cantilever beam. To exploit this phenomenon for high-throughput label-free biomolecular analysis, we have developed a chip containing a two-dimensional (2-D) array of silicon nitride cantilevers with a thin gold coating on one surface. Integration of microfluid cells on the chip allows for individual functionalization of each cantilever of the array, which is designed to respond specifically to a target analyte. An optical system to readout deflections of multiple cantilevers was also developed. The cantilevers exhibited thermomechanical sensitivity with a standard deviation of seven percent, and were found to fall into two categories-those whose deflections tracked each other in response to external stimuli, and those whose did not due to drift. The best performance of two "tracking" cantilevers showed a maximum difference of 4 nm in their deflections. Although "nontracking" cantilevers exhibited large differences in their drift behavior, an upper bound of their time-dependent drift was determined, which could allow for rapid bioassays. Using the differential deflection signal between tracking cantilevers, immobilization of 25mer thiolated single-stranded DNA (ssDNA) on gold surfaces produced repeatable deflections of 80 nm or so on 0.5-/spl mu/m-thick and 200-/spl mu/m-long cantilevers.

[1]  M. Bittner,et al.  Expression profiling using cDNA microarrays , 1999, Nature Genetics.

[2]  A. Steckenborn,et al.  Determination of Young's moduli of micromechanical thin films using the resonance method , 1992 .

[3]  Anja Boisen,et al.  Adsorption kinetics and mechanical properties of thiol-modified DNA-oligos on gold investigated by microcantilever sensors. , 2002, Ultramicroscopy.

[4]  T. Thundat,et al.  Bioassay of prostate-specific antigen (PSA) using microcantilevers , 2001, Nature Biotechnology.

[5]  A K Chakraborty,et al.  Origin of nanomechanical cantilever motion generated from biomolecular interactions. , 2001, Proceedings of the National Academy of Sciences of the United States of America.

[6]  M. Fujihira,et al.  Calibration of surface stress measurements with atomic force microscopy , 1997 .

[7]  J. K. Gimzewski,et al.  Photothermal spectroscopy with femtojoule sensitivity using a micromechanical device , 1994, Nature.

[8]  H. Rothuizen,et al.  Translating biomolecular recognition into nanomechanics. , 2000, Science.

[9]  G. Stoney.  The Tension of Metallic Films Deposited by Electrolysis , 1909 .

[10]  James K. Gimzewski,et al.  Surface stress in the self-assembly of alkanethiols on gold , 1997 .

[11]  R. Horowitz,et al.  Optomechanical uncooled infrared imaging system: design, microfabrication, and performance , 2002 .

[12]  Arun Majumdar,et al.  Optimization and performance of high-resolution micro-optomechanical thermal sensors , 1997 .

[13]  T. Thundat,et al.  Cantilever-based optical deflection assay for discrimination of DNA single-nucleotide mismatches. , 2001, Analytical chemistry.

[14]  R. Davis.  Old world archeology: central Asia. , 1985, Science.

[15]  Arun Majumdar,et al.  Nanomechanical Forces Generated by Surface Grafted DNA , 2002 .

[16]  Chong H. Ahn,et al.  Simulation of Flow in Structurally Programmable Microfluidic Channels , 2001 .

[17]  H. Lang,et al.  Multiple label-free biodetection and quantitative DNA-binding assays on a nanomechanical cantilever array , 2002, Proceedings of the National Academy of Sciences of the United States of America.