Novel Method Detects Kidney Cancer Biomarkers in Urine

A team of scientists created what they call bioplasmonic paper—filter paper impregnated with gold nanorods linked to antibodies that would bind to aquaporin-1. Gold nanorods respond to light by producing localized surface plasmon resonance (LSPR), a specific type of light emission that involves waves of electrons moving across the surface of metal nanostructures. LSPR is very sensitive to molecular events that occur on or near the surface of the particles, including binding of bimolecules to attached antibodies.

Traditionally, LSPR detection devices are rigid, flat surfaces such as glass, but Dr. Srikanth Singamaneni from the department of mechanical engineering and the Siteman Cancer Center at Washington University (St Louis, MO, USA) and colleagues demonstrated that standard filter paper can also serve as an LSPR substrate. The team found that the sensitivity and limit of detection for the paper-based system is at least as good, if not better, than for conventional rigid substrates. In this case, the limit of detection matched that of the range of aquaporin-1 levels in patients with kidney cancer. Other advantages of using paper include its wicking properties, flexible surface for collection, compatibility with standard ink jet printing technology, low cost, and ease of disposal.

The findings were published online on October 25, 2012, in the journal Analytical Chemistry.

Currently, the technology used clinically to detect specific proteins such as the two kidney cancer biomarkers, known as an enzyme-linked immunosorbent assay (ELISA), is both expensive and time-consuming, and requires a relatively high level of laboratory expertise to produce accurate results.

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