Accidents & Violence, Technology / 18.09.2015
Nanotechnology Can Improve PSA Sensitivity and Efficiency
MedicalResearch.com Interview with:
Dr. Xiaohu Xia Ph.D.
Assistant Professor
Department of Chemistry
Michigan Technological University
Houghton, MI 49931
Medical Research: What is the background for this study? What are the main findings?
Dr. Xia: Peroxidases, a family of enzymes that catalyze the oxidation of certain compounds with peroxides, have found widespread use in areas such as biomedicine and environmental protection. Over the past several years, researchers have found that certain inorganic nanomaterials (such as nanoparticles made of metal, metal oxides, and carbon) possess intrinsic peroxidase-like activities. As the major advantage over their natural counterparts, these peroxidase mimics are much more stable because they are less vulnerable to denaturation and protease digestion. In spite of the superior stability of the mimics, improvement in their catalytic efficiency has been met with limited success. The catalytic efficiencies for most of the previously reported peroxidase mimics with sizes 1-100 nm are limited to the range of 101-104 s-1 in terms of catalytic constant (Kcat, which measures the maximum number of chemical conversions of substrate molecules per second per enzyme/mimic).
Our research team have recently developed a new type of peroxidase mimic with a record high efficiency that was engineered by coating ~18 nm palladium (Pd) nanocubes with ultrathin iridium (Ir) skins of a few atomic layers (i.e., Pd-Ir core-shell cubes, see Figure). The catalytic efficiency of our Pd-Ir cubes could reach a level of Kcat = 106 s-1.
In view of the substantially enhanced efficiency, we applied our Pd-Ir cubes to the colorimetric enzyme-linked immunosorbent assay (ELISA) of human prostate surface antigen (PSA) by functionalizing their surface with antibodies. The detection limit of the Pd-Ir cubes-based ELISA of PSA was determined to be 0.67 pg/mL, which is over 100-fold lower than that of the conventional horseradish peroxidase(HRP)-based ELISA using the same set of antibodies and the same procedure (see Figure).
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