Researchers develop new raspberry-shaped nanoparticle for precision drug delivery

A newly discovered technique, reported in the journal Nanoscale, offers a low-cost way to enhance the effectiveness of existing drugs.

“If you take sand and heat it to 500 degrees Celsius, nothing changes,” said Bradley Smith, the Emil T. Hofman Professor of Science at the University of Notre Dame. So Smith, who is also the director of Notre Dame’s Integrated Imaging Facility, was puzzled when Canjia Zhai and Cassandra Shaffer, two doctoral students in the Department of Chemistry and Biochemistry who were working in his lab, discovered they had changed the structure of particles of silica — the main component of sand — at 80 degrees Celsius, a temperature similar to that of a cup of coffee.

The discovery happened by accident. The particles were microscopically small — a thousandth the diameter of a human hair. But like their larger counterparts marked “silica gel” in packages attached to new articles of clothing, these particles were porous and could retain a chemical. In this case, that chemical was a blue dye used to detect tumors in mice.

The new dye, which had been developed in Smith’s lab, was taking a long time to enter the narrow pores in the particles. So, to make the molecules move more quickly, Shaffer and Zhai warmed the mixture to just under boiling and left it overnight. When they returned the next day, they could see that the particles had turned blue.

To confirm that the dye had fully infused, Shaffer and Zhai enlisted the help of Tatyana Orlova and Maksym Zhukovskyi, microscopy experts at the Notre Dame Integrated Imaging Facility.

Orlova and Zhukovskyi produced high-resolution electron microscopy images that showed that not only had the dye infused, the silica particles themselves had changed shape. The original particles were solitary spheres lightly dotted with pores like the skin of an orange. The new structures were spherical and were composed of smaller dye-filled globules. They also had small openings here and there that revealed a hollow core inside. The overall unit resembled a hollow raspberry.

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