Good as gold​​​

It’s hoped that gold nanocages, paired with artificial antibodies, can be used for a test to detect acute kidney damage.

Gold is one of the world’s best-known precious metals. For thousands of years, it’s been crafted into jewelry, medals and coins. When mixed with alloys, it can take on a white or rose-colored cast, but its natural hue is a deep, rich, unmistakable yellow.

But chopped down in nano-sized bits (nanostructures), the metal becomes a chameleon, turning shades of green, blue, and even red, that can readily be seen with the human eye. The color changes are seen when the size and shape of the particles are changed or there is a change in the immediate environment surrounding the nanostructures.

It’s that color-shifting quality that researchers at Washington University in St. Louis are using to develop new technologies for medical diagnostic assays, and their current objective — to create an easily-utilized test for acute kidney damage that provides rapid results.

Singamaneni

Srikanth Singamaneni, PhD, associate professor of materials science in the School of Engineering & Applied Science, has received a two-year, $411,246 grant from the National Institute of Diabetes and Digestive and Kidney Diseases of the National Institutes of Health (NIH) to design and produce new biosensors that will combine gold nanocages and specifically engineered artificial antibodies to detect biochemical signs of kidney damage.

“Instead of using natural antibodies, which can take months or years to develop, we use artificial antibodies integrated with the gold nanostructures that eliminate the need for stringent storage and shelf-life constraints, and significantly lowers the cost of the biosensors,” Singamaneni said.

The plan is to imprint the nanocages with the artificial antibodies that are designed to mimic three natural antibodies that recognize three proteins usually present when there is acute or chronic kidney damage or injury: neutrophil gelatinase-associated lipocalin (NGAL), kidney injury molecule 1 (KIM-1) and fatty acid binding protein 1 (FABP1).

When present in urine or plasma, the protein biomarkers bind to the artificial antibodies on the gold nanocages, changing their resonance and thus, their color. That resulting color change indicates kidney disease or damage.

Singamaneni has been working for several years with Evan Kharasch, MD, PhD, the Russell & Mary Shelden Professor of Anesthesiology and professor of biochemistry and molecular biology at Washington University School of Medicine in St. Louis; and Jeremiah Morrissey, PhD, professor of anesthesiology at the School of Medicine. The NIH support will help the team design, create and develop a paper-based detection system using the gold nanocages.

“This technology will eventually allow more widespread, point-of-care testing for acute and chronic kidney disease, and enable testing settings such as rural or inner city clinics,” Singamaneni said.