'Micro-Rocket' Drug Delivery System Shows Promise

In a study published in SMALL, researchers developed microscopic silk swimming devices for drug delivery that are both biodegradable and safe for a biological system.

The approach shows potential for future use in humans as a form of drug delivery and locating cancer cells. These micro-rockets are made of safe, non-toxic material that will not cause any harm or injury to living tissue or biological environment.

The rockets are 300 microns in length and 100 microns in diameter, which is equivalent to the thickness of a single strand of human hair. The rockets also have the ability to create their own thrust that allows them to swim through any bio-fluid that contains this fuel.

The rockets were produced for the first time using an innovative 3D inkjet printing method that involves using a solution of dissolved silk mixed with an enzyme. The solution is placed into the printer and builds up layers of ink to create a column of the rocket.

Methanol is printed on top of the printed solution, triggering a reaction that forms a rigid rocket shape that traps the enzyme within a silk lattice structure. The enzyme then acts as a catalyst reacting with the fuel molecules to produce bubbles that push the rocket forward.

“By using a natural enzyme like catalyst and silk which are fully biodegradable, our devices are far more biocompatible than earlier swimming devices,” said researcher Xiubo Zhao. “The inkjet printing technique also allows us to digitally define the shape of a rocket before it's produced. This makes it a lot easier to optimize the shape in order to control the way the device swims.”