Science1 publisher2 min readPublished
A chemistry student's iPhone video shows metal nanoparticles forming from merging clusters
Carnegie Mellon senior Nivedita Shyamsundar tracked colour changes in iPhone video frame by frame to show metal nanoparticles form from merging clusters. Her program lets a lab time the fast early stages of such reactions with a camera it already owns.
The Scientist · Science desk
What happened
- Researchers making new metal nanoparticles in Jill Millstone's University of Pittsburgh lab could capture only the final stages of formation with their instruments.
- Shyamsundar filmed a reaction on her iPhone and checked the colour-change timings she read from the footage against the lab's own data.
- Millstone said her lab continues to use the analysis program Shyamsundar wrote.
- The work appears in the American Chemical Society journal Langmuir, with Shyamsundar as second author.
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Why it matters
- constraint The technique reads formation from colour, so only reactions that visibly change colour as their particles form can be timed this way.
- decision Chemists trying to steer how these metal particles grow now have to work with cluster merging, the route the video found, in place of the atom-by-atom growth the classical picture assumes.
- constraint Applying the method to drug- or vaccine-delivery particles, such as the lipid nanoparticles Shyamsundar studied at Moderna, would first need its own check against instrument data.
"The formation was happening way too fast to capture with typical lab technologies," Shyamsundar said [4]. "I wanted to come up with a more accessible way to see some of the kinetics of the nanoparticle formation," she said [5].
The raw signal was something the researchers had already noticed by eye: the solution changes colour as the particles form [6]. Video turns that into a time series. Each frame carries a timestamp, and the colour of the solution in that frame is the reading [7]. Checking those readings against the lab's data [7] tested the phone on the late part of the reaction the instruments could record, before it was relied on for the early part they could not [3].
Once the approach was written into a program [8], the team used it to work out how the particles form [9]. "We found out the formation mechanism wasn't the classical one of metal atoms coming together one by one," Shyamsundar said [10]. "It was actually clusters of metal atoms coalescing." [11] The result covers the new metal nanoparticles that lab was making [2]. The phys.org account does not name the metal, give the camera's frame rate or say how long the reaction ran [7].
Shyamsundar's own interest is particles for medicine. Her current project anchors a ligand shell to a nanoparticle core, so that the shell hides a chemotherapy drug around healthy cells and releases it in the acidic environment near tumours [14]. "Changing ligand shell behavior has the potential to make a big impact on how the drug releases," she said [16]. During an internship at Moderna, she studied factors affecting the formation of lipid nanoparticles for vaccine delivery [15].
In the account, the camera program belongs to the metal-particle work in the Millstone lab, where it is still in use [2][13].
What to watch
- Whether the Langmuir paper reports the video's time resolution and how closely its colour timings matched the lab's instrument data.
- Whether groups outside the Millstone lab adopt the program, particularly for lipid or other delivery nanoparticles.
- Whether cluster coalescence also appears when the method is used on other metals or reaction conditions.