Nanoparticles can transport a variety of molecules, including antibodies, drugs and catalysts, thanks to their large surface-to-volume ratio. Such applications are limited, however, because most nanoparticles disintegrate or bunch together when exposed to high temperatures and certain chemicals. Nanoparticles made from borosilicate glass instead of silica glass or polymers would overcome these limitations but it has been difficult to make such particles until now because the boron oxide precursor materials are unstable.
Martin Gijs, Virendra Parashar and co-workers began by preparing a borosilicate solution from tetraethylorthosilicate and trimethoxy boroxine using formic acid as a catalyst and dichloromethane and isopropanol as solvents. Next, the researchers exposed a drop of this solution to water, which led to a dynamic reaction, causing solid nanoparticles to "burst out" of solution. The particles were around 100–500 nm in size.
"These nanoparticles could replace the conventionally used silica particles in high-end applications where stability is required," Parashar told nanotechweb.org. Aside from biomedicine (drug delivery and medical imaging), such applications include photonic bandgap devices, contrast agents for ultrasonic microscopy and filtration membranes.
The team would now like to be able to control the size and production yield of the particles. Both parameters are difficult to manage because of the fast surface reaction involved.
The work was published in Nature Nanotechnology.