RII Track-4: The Integration of Plasmonic Nanoantenna and Super-hydrophobic Surface for Ultrasensitive Fluorescence CRISPR Biosensing

Early diagnosis provides significant and unprecedented benefits since patients diagnosed at an early stage of diseases often have a good chance for cure and functional outcomes. In addition, rapid testing is crucial to combat the pandemic as exemplified by the ongoing COVID-19 pandemic. This project aims to design a direct Clustered Regularly Interspaced Short Palindromic Repeats (CRISPR) based point of care diagnostic system without pre-amplification of viral genomes. It will allow ultralow and ultrasensitive detection of many diseases (e.g., cardiovascular diseases, cancer, and infectious diseases) at an early stage when the concentration of viral genomes in body fluids (i.e., urine, blood, saliva) is still very low and not sufficient to be detected by existing technologies. This NSF EPSCoR RII Track-4 fellowship provides the opportunity to collaborate with a renowned expert in point-of-care diagnostics for infectious diseases in the Department of Biomedical Engineering at the University of Connecticut to achieve this goal. The successful completion of this project will lead to noninvasive, inexpensive, mass-producible systems for early detection, treatment outcome evaluation of diseases, greatly improving patient morbidity and reducing healthcare cost, particularly important to Nevada, which consistently ranks near the bottom in terms of higher rates of the 12 leading causes of death.The objectives of the project are to (1) integrate nanoantenna with super-hydrophobic surfaces for enhancing the CRISPR/Cas12a detection sensitivity without pre-amplification; (2) integrate the designed enhanced CRISPR/Cas12a fluorescence detection module with microfluidics for viral detection in the blood sample. Although CRISPR based point of care diagnostic system has emerged as a popular technology and a powerful tool for rapid screening due to its simplicity and flexibility, it still has many limitations such as low stability in complex biological samples. One promising solution is to explore the nanoantenna technique to trigger the enhanced Localized surface plasmon. However, the nanoantenna technique is still far from being routinely implemented in biomedical fields due to a major obstacle not from plasmonics but from the mass transport: Most nanoantennas typically rely on diffusion to capture target molecules, which makes the detection time impractically long. This project integrates the nanoantenna with the superhydrophobic surface to address this diffusion limit. Droplets over super-hydrophobic surfaces maintain quasi spheres during evaporation and do not wet the surface. Therefore, the droplet evaporation replaces the diffusion and concentrates molecules onto the sensitive regions of the nanoantenna, becoming the dominant mechanism of mass transfer. The droplet evaporation time is not only much shorter than the diffusion time but also can be actively controlled, which is an additional benefit. The combination of plasmonics and super-hydrophobic surfaces offers a unique solution to the aforementioned key challenge and holds the promising for ultralow and ultrasensitive biosensing platforms enabled by CRISPR. The training and research experience provided by this RII Track-4 fellowship will allow the PI to successfully transition from the background of material science and engineering to a biomedical researcher.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.