Sprecher
Beschreibung
Continuous biosensors rely on affinity-based nanoswitches that undergo target-induced conformational changes and as such enable real-time biomarker detection in healthcare and biotechnology applications1. However, developing sensitive and fully reversible affinity-based nanoswitches for continuous biosensing is hindered by limited understanding of their mechanism of action.
We recently developed a fiber optic surface plasmon resonance (FO-SPR) biosensor using affinity-based DNA nanoswitches with AuNPs for sensitive target detection via competitive DNA hybridization2. To deepen our understanding of nanoswitches’ behavior, in this work we demonstrate a novel approach of imaging AuNPs tethered to the gold-coated surface of an optical fiber. By exciting localized surface plasmons on the AuNPs via propagating plasmons on the gold film, we resolved 40 nm AuNPs with high signal-to-noise ratio and low background scattering. This single particle (SP) method established a robust toolbox for analyzing nanoswitches’ behavior by enabling simultaneous, nanoscale tracking of the distance of AuNPs from the surface through intensity changes, as well as their XY motion at the nanoscale over time.
Our SP tracking approach offered previously inaccessible insight into the nanoswitch heterogeneity, providing spatial and temporal information about their behavior. Additionally, it visually confirmed that the bulk signal originates from the spatial redistribution of AuNPs upon target binding.
In conclusion, we believe these SP measurements pave the way for advancing mechanistic understanding of nanoswitches’ behavior, promoting the design and development of novel nanoswitches. This platform will provide quantitative insight into the influence of key parameters such as AuNP-film spacing and the affinities among different bioassay components (e.g., the capture probe, competitor, and target) on nanoswitch performance.
[1] Dillen, Lammertyn, Analyst 2022, 147, 1006–1023.
[2] Dillen et al., ACS Sensors 2023, 8 (2), 811-821.
