InsightChips had a successful product demo with Dr. Paricash Moradifar and PhD candidate Amy McKeown-Green from the Dionne Lab at Stanford University. Interesting experiments took place with galvanic replacement on gold nanorods, enabled by the latest advancements in Nano Channel Chip fabrication by our industrial PhD candidate, Niccolò Bottauscio.
The experiment utilized Insight Chips’ Nano Channel Chips with traps – a way to confine nano channels even further, effectively filtering particles that otherwise would have flowed through the channels.
The trap chips encapsulate the liquid in the same way as all our Nano Channel Chips. The difference with these chips is that an ~80 nm liquid layer is confined even further to a 5-10 nm liquid layer. The particles in this experiment had a thickness of more than 30 nm and therefore could not pass through this narrow region.
While being able to trap particles very effectively, the chips are still equipped with four inlets/outlets, making it possible to flush in new liquids while the chip is inside the TEM. That’s what made it possible in this case to do the galvanic replacement while recording the event!
A water-based solution of 30 x 80 nm gold nanorods was prepared for the chips by simply pipetting a <1 µL droplet onto one of the four inlets in the chip. Capillary forces pull in this liquid, and as it flows through the nano channels, particles are filtered and left behind in the traps.
When the holderwas inserted into the TEM, the particles are immediately spotted in the traps:
With the particles clearly imaged, two liquids could be introduced into the nano channels to initiate the galvanic replacement.
The liquids, in this case, were H2PdCl4 and AgNO3: Here, palladium ions replace gold on the nanorods due to differing redox potentials.
The difference before and after is clearly seen in these two images:
Zooming infurther on the gold rods clearly shows shells forming around the particles:
In thefuture, we hope to do more liquid cell experiments with Dr. Pari and Amy. For now, we thank you for the opportunity to come and showcase our technology with you.
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