Diagnostic test strips functionalized with gold nanoparticles have been developed to detect pregnancy as well as tuberculosis and other infectious diseases. Application of this technology to cancer diagnosis is hampered by the minute concentrations of relevant biomarkers in blood. The paper strips aren’t sensitive enough in the presence of these low indicator levels to induce a color change obvious to the human eye.

Michigan Technological University researchers determined that such a simple cancer diagnostic can be achieved By coating nanoparticles in thin layers of platinum, researchers increased the sensitivity of test strips that detect prostate-specific antigen. (Source: Michigan Technological University)by adding a dual function (plasmonics and catalysis) to the nanoparticles with ultra-thin platinum skins. Test sensitivity and accuracy increase with the platinum coating, and color changes are easier to observe.

The team developed a low-sensitivity mode (red color from gold nanoparticle cores) and a high-sensitivity mode (color produced by platinum skins through catalysis) to detect prostate-specific antigen (PSA). The high-sensitivity mode greatly improves test strip visibility; the low-sensitivity mode is on par with commercially available test strips.

The assay reacted to PSA signals measuring mere trillionths of a gram in a single drop of blood. The researchers point out that the use of thin platinum coatings will not markedly impact the cost of current gold nanoparticle test strips. The diagnostic design is deemed compatible with detecting other kinds of cancer biomarkers.