A new type of lab-on-a-chip could make it easier to determine the effectiveness of a promising cancer treatment that combines photosensitive drugs, light, and oxygen.

The treatment, known as photodynamic therapy (PDT), uses a unique type of drug, called a photosensitizer, that generates high-energy oxygen when activated by light, in this case an LED laser.

The oxygen reaction destroys cells locally only in the immediate surrounding area, which in this case is the tumor, without damaging other healthy cells in the rest of the body. PDT may also prompt the patient’s immune system to attack the tumor, whereas without treatment it will likely ignore it.

“PDT is a fairly complicated therapy because it requires light, oxygen, and the drug, all three of which need to be carefully controlled,” says Xia Lou, a postdoctoral fellow at the University of Michigan. “With chemotherapy, for example, you only control how much of the drug is used.”

The biochip can test the interaction of the drug, light, and oxygen simultaneously, generating results in a fraction of the time of current testing practices.

“In cancer research doctors are always looking for better drugs,” adds Lou. “But there has always been a lack in the ability to efficiently test new drugs.

“Researchers are also hoping to get more reliable test results than is the norm. We are providing more precise drug test conditions to insure that the results we are getting will more closely match the actual results from cancer treatment.”


There are two primary challenges in PDT today. One is determining the best treatment plan for the patient, and the other is testing the efficacy of new and existing drugs.

For example, the location of a tumor in the body will determine the amount of light needed to excite the drug, and will impact the amount of drug that is administered. Also, when testing new drugs, it is again important to know the amount of light needed to excite the oxygen reaction, and the strength of the reaction.

This adds a high level of complexity compared to conventional drug testing that only tests one component, the drug itself.

Current PDT testing methods might take more than 24 hours to acquire just 10 data points.

“With our device,” says Lou, “we can finish the testing in 1 hour and have 1,000 data points. The result is a very comprehensive understanding of how the 3 elements need to be manipulated for maximum effect in an individual patient.”

The researchers reported the details of their findings in the journal Lab on a Chip. The NSF Engineering Research Center for Wireless Integrated Microsystems, Thermo Fisher Scientific, and the National Institute of Health supported the project.

Source: University of Michigan


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