Exploiting the Anti-Aggregation of Gold Nanostars for Rapid Detection of Hand, Foot, and Mouth Disease Causing Enterovirus 71 Using Surface-Enhanced Raman Spectroscopy

Enterovirus 71 (EV71) is a major public health threat that requires rapid point-of-care detection. Here, we developed a surface-enhanced Raman spectroscopy (SERS)-based scheme that utilized protein-induced aggregation of colloidal gold nanostars (AuNS) to rapidly detect EV71 without the need for fabricating a solid substrate, Raman labels or complicated sample handling. We used AuNS (hydrodynamic diameter, D H of 105.12 ± 1.13 nm) conjugated to recombinant scavenger receptor class B, member 2 (SCARB2) protein with known affinity to EV71. In the absence of EV71, AuNS-SCARB2 aggregated in biological media and produced four enhanced Raman peaks at 390, 510, 670, and 910 cm –1 . In the presence of EV71, the three peaks at 510, 670, and 910 cm –1 disappeared, while the peak at 390 cm –1 diminished in intensity as the virus bound to AuNS-SCARB2 and prevented them from aggregation. These three peaks (510, 670, and 910 cm –1 ) were potential markers for specific detection of EV71 as their disappearance was not observable with a different dengue virus (DENV) as our control. Furthermore, the Raman measurements from colloidal SERS were more sensitive in probing the aggregation of AuNS-SCARB2 for detecting the presence of EV71 in protein-rich samples compared to UV–vis spectrum measurements. With this facile “anti-aggregation” approach, we were able to detect EV71 in protein-rich biological medium within 15 min with reasonable sensitivity of 10 7 pfu/mL and minimal sample preparation, making this translatable for point-of-care applications.