PORTLAND, Ore. -- Thin-films are enabling implantable pharmacies-on-a-chip that use electric fields to dispense drugs on-demand, rather than depend on patients remembering to take their meds. The implants could also be located directly at the site where they are needed; for instance, automatically dispensing cancer drugs at a surgery site when active circuitry on the chip senses that an excised tumor starts to regrow.
"Our thin films are addressed directly with an applied electrical field," said Professor Paula Hammond at the Massachusetts Institute of Technology (Cambridge). "Dispensing what is needed, exactly when and where it's needed."
The 150-nanometer-thick films are constructed from alternating layers of a negatively charged pigment and positively charged drug molecules (or a neutral drug wrapped in a positively charged carrier molecule). When an external electrical field is applied to the film, the negatively charged pigment layer loses its polarity causing it to dissolve, thereby releasing the drug beneath it. By using a precisely timed alternating current, the amount of drug dispensed can be precisely controlled, according to Hammond.
In the doctor's office, the electric field could be directly applied with a handheld instrument, or, at home, radio signals could be used to remotely deliver drug doses. The researchers are also working on sensors that can sense the conditions under which a drug should be dispensed, such as dispensing insulin whenever a diabetic has high blood sugar.
So far, the researchers have only fabricated passive pharmacies-on-a-chip and demonstrated that they can release test-molecules when an external electrical field is applied. Next, the researchers plan to design complete implants with active electronic components and loaded with real drugs that can be tested on animals in clinical trials. Hammond estimates that it will take at least five years before human trials could begin.
Hammond performed the work with MIT doctoral candidate Daniel Schmidt, postdoctoral associate Kris Wood at the Broad Institute of MIT and Harvard, and postdoctoral associate Nicole Zacharia at the University of Toronto.