Detection Of Prostate Specific Antigen With Nanomechanical Resonators

Main Category: Prostate / Prostate Cancer
Also Included In: Urology / Nephrology;  Cancer / Oncology
Article Date: 30 Dec 2009 - 0:00 PDT

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UroToday.com - Detection of PSA with increasing sensitivity may enhance several aspects of disease monitoring. Micro- and nanoelectromechanical systems (MEMS and NEMS) are new devices for detection of infectious agents and disease biomarkers. These systems are of small size and high sensitivity making them good candidates for miniaturized sensor systems and amenable to multiplexed detection through the use of arrays of devices that could be uniquely functionalized and have on-chip redundancy for detection of each analyte. The sample can induce a surface stress causing a tip deflection in the case of static mode sensors or a change in the mechanical properties or the mass of the devices resulting in a resonant frequency shift for dynamic mode sensors.

The paper addresses detection of PSA by new biotechnology. Detection of an analyte from serum is confounded by the non-specific binding of other background proteins or biomolecules to the sensor surface. This can physically block the binding and detection of the desired analyte. This study used a sandwich assay-based, secondary mass labeling technique to detect PSA. Arrays of trampoline resonators were functionalized with capture antibodies specific to PSA and a second antibody was used to specifically tether nanoparticle mass labels to PSA molecules attached to the devices. PSA was detected from undiluted serum at concentrations ranging from 50ng/ml down to 50fg/ml, or 1.5 fM.

Preliminary experiments demonstrated that blocking and washing procedures were effective to detect PSA in the presence of serum and did not strongly affect the frequency responses due to nanoparticle labels. The 50fg/ml frequency shift was found to be significantly different from a null shift using a one-tailed, Student's t-test. Also, shifts for all concentrations were different from neighboring concentrations. Scanning electron micrographs show nanoparticles bound to the resonators with increasing amounts bound at increasing PSA concentrations. The flexibility of the sensors used in this assay was limited only by the availability of specific biorecognition layers and functionalization techniques.

Waggoner PS, Varshney M, Craighead HG

Lab Chip. 2009 Nov 7;9(21):3095-9
10.1039/b907309b

Written by UroToday.com Contributing Editor Christopher P. Evans, MD, FACS

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