Penn State-led researchers have used nanomaterials' heterostructures to develop the first rapid test for mpox, commonly known as monkeypox.
The technique, published recently in Advanced Functional Materials, uses gold nanoparticles and hafnium disulfide nanoplatelets as building blocks to create a platform for detecting trace amounts of genetic material.
Human mpox was first identified in the Democratic Republic of Congo in the 1970s and was considered endemic only in parts of Africa. However, since 2022, mpox has spread to 100 countries, causing over 86,900 infections worldwide; approximately 33% are concentrated in the U.S.
Transmitted primarily through close physical contact, mpox causes symptoms similar to smallpox, although less severe. While current caseloads are low, warmer weather and increased human activity could cause cases to spike as they did last summer. People can spread mpox days before symptoms appear, making early detection critical to mitigating spread.
Current tests require skilled healthcare providers to swab lesions and send samples to labs for testing, which in turn requires several days and expensive instrumentation for polymerase chain reaction (PCR) -- currently the only type of U.S. Food and Drug Administration (FDA)-approved mpox test. Given these limitations, PCR testing, plus the two-dose vaccine, have been insufficient at stopping contagion. By contrast, a non-PCR test that detects the virus within minutes could dramatically slow the virus’s transmission.
To meet this challenge, the researchers employed plasmonics, the manipulation of light flow using tiny metallic nanoparticles whose size and shape provide unique optical properties. They layered spherical gold nanoparticles, refined to a zero-dimensional scale, with hafnium disulfide, an inorganic, two-dimensional compound a few atoms thick. The gold nanoparticles and hafnium nanoplatelets interacted to form heterostructures that functioned as highly accurate sensors, with optical properties that changed dramatically in the presence of external signals.
In this case, the signal came from trace amounts of viral DNA, specifically the conserved region of the mpox virus genome not subject to mutations. Adding mpox viral DNA to the nanocomposite surface increased the agglomeration between gold nanoparticles and decreased the π-stacking distance between the hafnium nanoplatelets.
The researchers say that they hope their technique could in the future facilitate simple, rapid, selective mpox diagnosis, preventing future spread. Since the technique is adaptable for future mutations and emerging pathogens, they are testing their system against other pathogens to confirm its broad applicability. If the system and tests can be validated, they will seek commercial partners to market the technology.
“We were interested in developing a sensitive detection method for pathogens generally, and also wanted to apply the concept to an emerging pathogen like mpox, because there is a real-world urgency for this rapid nucleic acid test,” Dipanjan Pan, study leader and Penn State nanomedicine professor, said in a statement.