Monitoring human health needs frequent biochemical logging, but low-cost ultrasensitive sensors do not yet exist. Our team exploits metal nanostructures that vastly amplify signals from small molecules controlling metabolism, such as neurotransmitters. Vibrational spectroscopy called surface-enhanced Raman scattering (SERS) previously failed because of irreproducibility, fouling, and degradation. Our new ‘plasmonic’ devices give uniform intense signals, can be recleaned, giving many applications.
Current work:
Monolayer aggregates for SERS sensing
We have developed a way to glue gold nanoparticles (50-200nm diameter) into close-packed sheets (MLaggs), by using a binding molecule to self-assemble them at the interface between two immiscible liquids. This makes precision nanogaps only 0.9nm wide that trap light, massively enhancing SERS signals of analytes that wash over the MLaggs. This robust scalable and low-cost assembly with precision nanogaps opens up a wide range of possibilities. [1]
SERSbot for automated sensing
Essential for progress is to compare different protocols for SERS, and how they can be used quantitatively and reproducibly. We have built a SERSbot to show signals can be repeatable within a few %, and also how molecules compete for binding sites. [2,3]
Cleaning and reuse of SERS using MLaggs
We have devised a way to remove all organic molecules from nanogaps, by oxidising the top three atomic monolayers of Au, and then rescaffolding the gap while reducing the AuO. This allows us to cycle the devices hundreds of times, and sense a wide range of analytes, including neurotransmitters. [4,5]
Key papers:
- Controlling atomic-scale restructuring and cleaning of gold nanogap multilayers for SERS Sensing, ACS Sensors (2023); DOI 10.1021/acssensors.3c00967
- Eliminating irreproducibility in SERS substrates, J.Raman Spectroscopy 52, 412 (2020); DOI: 10.1002/jrs.6008
- SERSbot: Revealing the Details of SERS Multianalyte Sensing Using Full Automation, ACS Sensors (2021); DOI: 10.1021/acssensors.1c02116
- In situ electrochemical regeneration of nanogap hotspots for continuously reusable ultrathin SERS sensors, Nature Comm. (2024); DOI: 10.1038/s41467-024-46097-y
- SERS sensing of dopamine with Fe(III)-sensitised nanogaps in recleanable AuNP monolayer films, Small (2023); DOI 10.1002/smll.202302531
Current people involved:
JJB, Sarah Sibug-Torres, Elle Wyatt, Tabby Jones, Nicolas Spiesshofer, Ibrahim Kanber, James Beattie, Marika Niihori