Swapping blood for spit -- for convenient at-home health monitoring

Blood tests provide critical information about a person's health. But they also rely on uncomfortable procedures, ranging from collecting small blood samples through frequent finger pricks to blood draws from a trained phlebotomist. Saliva has been explored as an alternative way to track important biomarkers, including glucose. However, most methods for analyzing saliva samples for small molecules require laboratory equipment. To make the analyses convenient for at-home testing, a simple, yet accurate, sensing platform is needed. One possibility is the electrochemical aptamer-based (E-AB) biosensor, which produces a measurable, electrochemical change when a specially designed piece of DNA or RNA, known as an aptamer, binds to its desired target. This type of device has previously been used on blood samples, but this time, Philippe Dauphin-Ducharme and colleagues adapted E-AB biosensors for saliva samples. The team wanted to measure the concentration of glucose and AMP -- a small molecule biomarker associated with gum disease -- in real saliva specimens.

The team took previously reported DNA aptamers that bound to either AMP or glucose, then re-engineered them to improve their sensitivity. They created their E-AB biosensors by mounting the aptamers on a gold electrode. Saliva samples were collected from a group of participants and pooled together. The sensors were then immersed in the saliva, with no additional preparation steps or reagents needed. This simplicity makes the test easy enough to be performed by a patient in their home. In experiments, the researchers found that their devices returned a result within 30 seconds, remained stable in undiluted saliva for up to three days and retained sensitivity for up to a week, if washed after each use. Additionally, the glucose sensor shows high selectivity towards its target, and both the AMP and glucose sensors are sensitive enough to detect the biomarkers at much lower concentrations than typically found in saliva. The researchers say that this simple technology is the first of its kind to detect glucose in human saliva, and they hope it can make at-home health monitoring less invasive and easier to complete, especially for people with chronic diseases such as diabetes.

The authors acknowledge funding from Colgate-Palmolive Company and the Alliance Grant program of the Natural Sciences and Engineering Research Council of Canada. Some authors are employees of Colgate-Palmolive's Research and Development Center.

The authors have patents pending on this technology.