Nanotechnology is leading the way toward another solution for an expensive, energy-consuming process: this time, it's doctors in remote areas who need to send lab specimens for testing to hospitals that can often be hundreds of miles away.

Traditionally, it's been necessary to preserve the quality of long-distance-traveling samples, such as blood or urine, through refrigeration. But a team of researchers at Washington University in St. Louis has eliminated that need by developing a new low-cost technique that creates a protective shield around protein biomarkers in the sample — and maintains up to 95 percent of their purity.

The team used a nanoporous material to essentially "shrink-wrap" those protein biomarkers by growing crystals around the molecules. They then transferred the shrink-wrapped molecules onto standard lab filter paper; once dry, the paper can be shipped to a lab for testing without concern for maintaining a given temperature. At the lab, the molecules are extracted from the paper back into liquid, and specimen integrity is maintained.

The success of the technique draws upon the properties of an emerging class of nanomaterials known as metal-organic frameworks. The same team has previously published research on growing these nanomaterials to eliminate the need for refrigeration in the storage of biodiagnostic chips.

“We asked: Why we couldn’t apply the same technology to preserve the biospecimen, instead of preserving the biosensor?” says Srikanth Singamaneni, an associate professor of mechanical engineering and materials science.

To test the technique, the researchers used artificial urine samples spiked with a biomarker for acute kidney injury and blood samples spiked with a biomarker for ovarian cancer. Samples were mixed with precursors of the nanoporous material ZIF-8, then left to dry at room temperature. Bioanalytical techniques were used to gauge biomarker preservation levels between 85-95 percent. Similar results were seen with a real-world test in which the researchers sent the paper with dried samples on a 10-day round trip through the postal mail.

The researchers believe the method has wide applicability — including use in developing countries with limited access to health care and electricity, and deployment in emergency situations with scarce resources. The team has worked with the university technology management office to patent the technology, and plans to develop it into a product available to the health-care industry. Ultimately, they envision a biopreservation "kit" that would include the ZIF-8 precursors, paper strips and other materials needed, enabling patients in underserved areas to prepare their own blood or urine samples and send them to hospitals or labs.

The study is published in the journal Chemistry of Materials.