Diffraction-Based Cell Detection Using a Microcontact Printed Antibody Grating

Abstract

An optical detector has been fabricated that is specific for targeted bacterial cells, by stamping an antibody grating pattern on a silicon surface. The antibody grating alone produces insignificant optical diffraction, but upon immunocapture of cells, the optical phase change produces a diffraction pattern. This technique eliminates much of the surface modifications and the secondary immunochemical or enzyme-linked steps that are common in immunoassays. Microcontact printing provides an alternative to previously reported photolithographic-mediated antibody patterning processes and uses a photolithographic process simply to produce the elastomeric stamp. We have stamped antibodies directly onto clean native oxide silicon substrates with no other chemical surface treatments. Direct binding of the antibodies to the silicon occurs in a way that still allows them to function and selectively bind antigen. The performance of the sensor was evaluated by capturing Escherichia coli O157:H7 cells on the antibody-stamped lines and measuring the intensity of the first-order diffraction beam resulting from the attachment of cells. The diffraction intensity increases in proportion to the cell density bound on the surface.

Interferometric Methods for Label-Free Molecular Interaction Studies

“…Early studies by St. John et al demonstrated that diffraction optics can be used to detect whole bacteria cells captured using an antibody grating stamped on a silicon surface. 42 In 2005, Goh et al demonstrated the ability of diffraction optics to measure two different binding interactions simultaneously without the use of labels. To achieve this, receptor molecules mouse IgG and rabbit IgG were immobilized in two different patterns via PDMS stamping on the same 2D surface.…”

Investigation of the operating mechanism of a diffraction-based sensor

“…Diffraction-based sensors (DBSs) are a novel new class of biodiagnostic sensing devices that are inexpensive, easy to operate and capable of quantifying biological analyte concentrations for a variety of systems [1][2][3][4][5]. The basic operating principle of the DBS is that biological "target" molecules are patterned onto a substrate surface in the form of a diffraction grating.…”

Diffraction-based assay for detecting multiple analytes

“…Diffraction is an old concept, and its use in the detection of analytes has recently been investigated [1,2,3]. Diffraction occurs due to the wave nature of light: when light hits a non-random pattern of obstacles, the resulting constructive and destructive interference will result in a clear diffraction image.…”