Intellectual Merit

A method that can enable a rapid, portable, and inexpensive detection of specific pathogens, such as COVID-19, will play an important role in public health, economic stability, and the national security. Currently, the gold standard for detecting COVID-19 is the reverse transcription polymerase chain reaction (RT-PCR), which is time consuming (> 1 hour) and expensive. It also requires trained personnel and lab space. This project has investigated a new method that enables a fast, portable, and inexpensive detection of COVID-19. In our approach, target oligonucleotides (T-oligos) having a COVID-19 sequence are sandwiched between two different types of Au nanoparticles, 50 nm capture Au nanoparticle (C-AuNP) and 30 nm detection Au nanoparticle (D-AuNP). On the C-AuNP and D-AuNP surfaces, capture DNA (C-DNA) and detection DNA (D-DNA) is immobilized, respectively. The sequence of the C-DNA is made complementary to a portion of COVID-19 T-oligo, and the sequence of the D-DNA complementary to the other portion of T-oligo, enabling a specific capture of COVID-19 T-oligos and producing core-satellite nanoparticle conjugates (COVID-19 T-oligo is sandwiched between C-AuNP and D-AuNP). The core-satellite nanostructures are then detected optically or electrically. This approach has enabled a rapid detection of COVID-19 T-oligos, with a total hybridization time only 3 minutes (2-minute hybridization to capture T-oligos by C-AuNPs and 1 minute of T-Oligo/D-AuNP hybridization to form the core-satellite nanostructures). Even including other miscellaneous times (e.g., time for rinsing), our method enables detection of COVID-19 T-oligos in less than 5 minutes. The detection sensitivity of our method is as high as 500 fM; the core-satellite nanostructures can be formed in 3-minute total hybridization time at 500 fM T-oligo concentration. We have also demonstrated that the formed core-satellite nanostructures can be readily identified by UV-VIS spectroscopy, in which the core-satellite nanostructures produce a plasmon resonance peak at ~620 nm. Importantly, our detection of COVID-19 T-oligos is carried out on a very small substrate (6 mm by 9 mm), enabling pathogen detection in the field (e.g., doctor?s office, airport, battlefield). Our detection units are fabricated using widely available microelectronics fabrication technology, allowing mass productions at a very little cost. Our method has a potential to be used as a rapid and inexpensive initial screening of various pathogens in the field.

Broader Impacts

The public health, our economy, and the national security critically depend on well-trained and creative work forces in science and engineering fields. This project has provided graduate and undergraduate students excellent opportunities to develop their technical skills and broaden their knowledge, shaping them as creative scientists and engineers who can lead future innovations. This project has enabled training of two PhD students, three master students, and two undergraduate students. Healthy and diversified workforce would be an important element for global leadership in science and engineering. Aiming for creating diversified scientific leadership, this project has provided trainings for students in the underrepresented minority (URM) group. One URM PhD student and two URM undergraduate students have been trained throughout this project. The research outcomes that this project produced can contribute to preparing for future pandemics. The ability to detect a specific sequence of oligonucleotides in a short time (<5 minutes) in the field and inexpensively produce the detection units on a large scale can contribute to protecting people in health crises, protecting the economy, and ensuring the national security.

Last Modified: 03/30/2023
Modified by: Seong Jin Koh