In the world of medicine, there is heavy emphasis placed on curing diseases. But how can you cure a disease without knowing it’s there?
There are several diseases that are commonly undiagnosed or misdiagnosed due to the medical profession’s current reliance on outdated, unreliable, or altogether absent diagnostic techniques, tests, and devices. While some cases of these diseases would be fairly easy to cure, they continue to evade treatment due to issues in detecting them. Two of these diseases that I am most interested in are sepsis and prostate cancer.
Sepsis is the body’s life-threatening response to bacterial infection. More than 1.5 million people get sepsis every year in the United States alone. One in three of these patients will die in the hospital from the condition – the leading cause of death in hospitals in the U.S. Accurate diagnosis of sepsis and early intervention in the emergency room represent life saving measures. Unfortunately, sepsis is often undetected because current diagnosis procedures primarily rely on physical examination or time-consuming laboratory tests. This time delay can result in septic shock, organ failure, and death.
Prostate cancer is the second most common form of cancer in American men, as well as the second most common cause of cancer-related death. It is crucial to develop ways to detect prostate cancer in its earliest stages, as the likelihood of survival increases with early diagnosis. A prostate specific antigen (PSA) screen is currently used to diagnose prostate cancer. This test is relatively unreliable, as it is associated with a high false-positive rate, since many non-cancerous conditions can contribute to an increase in PSA in the blood.
The research that I do aims to develop devices that can improve the diagnosis of these two diseases, making eventual treatment faster and more reliable. These devices are known as electrochemical biosensors. Through the use of biochemical reactions (similar to the reactions that go on in your body after you eat a delicious meal), these biosensors can measure the level of targeted molecules that result from the reactions. They provide continuous signaling in real time, which means a patient suffering from an illness would not have to wait as long for that illness to be diagnosed and treated.
The two main measures of biosensor performance are sensitivity and selectivity. Sensitivity refers to the sensor’s ability to accurately measure the amount of the targeted molecule. Selectivity, on the other hand, describes how well the sensor can discriminate against interfering substances and measure only the targeted molecule.
In the case of sepsis, a high blood level of the targeted molecule lactate is a reliable indicator of infection and the amount can indicate its severity. Decreasing levels of lactate are associated with better survival prospects. Given this information, a bedside lactate biosensor capable of real-time monitoring of blood lactate levels would represent an impactful diagnostic tool for physicians to provide more immediate, accurate and effective treatment of sepsis.
In the case of prostate cancer, the targeted molecule sarcosine has shown potential as a biomarker for early stage prostate cancer. While sarcosine appears in negligible amounts in the urine of healthy individuals, prostate cancer patients have significantly elevated sarcosine levels in their urine. Importantly, because sarcosine can be detected non-invasively in urine samples, it represents an attractive diagnostic alternative to the current PSA screen for physicians.
For the last three years, I have been doing exactly that – developing these electrochemical biosensors to detect both sepsis and prostate cancer. If you are interested in reading more, see these papers we have published on lactate and sarcosine sensing.
In a few weeks, I’ll be starting medical school, and I know that when I am a doctor, I would hope to have these tools available for diagnosing diseases in my patients. And I would certainly want them if I was the patient!
-Najwa Labban, BMB Major 2019