A recently published study looked at a biosensor able to non-invasively detect the brain-derived neurotrophic factor (BDNF) in human saliva.
“The ultralow levels of BDNF in saliva is directly associated with major depressive disorder (MDD), also known as depression,” study author Paulo A. Raymundo-Pereira told us. “I didn’t expect to discover anything. I simply used my expertise in chemistry and biotechnology and we worked hard to optimize the disposable device to selectively detect ultra-low concentrations of BDNF in saliva without interference.”
According to data from the World Health Organization (WHO), more than one billion people live with mental disorders, with anxiety and depression being the most prevalent conditions. According to the organization’s reports, including the Mental Health Atlas 2024, these disorders have increased in prevalence in all countries, affecting people of all ages and income levels.
“Depression affects approximately 17% of the global population at some point in their lives, resulting in major social and economic consequences,” Raymundo-Pereira told us. “Indeed, depression currently affects 280 million people worldwide, according to WHO estimates, being a leading cause of disability.”
It is different from habitual mood fluctuations and short-lived emotional responses to the challenges of everyday life. Most episodes of depression are classified as moderate or severe and may lead to a great loss of quality of life and productive years. More than 700,000 people globally die by suicide every year, making it the third leading cause of death in young people aged 15 to 29 globally in 2021 according to WHO.
“We present a cost-effective and disposable electrochemical immunosensing strip for rapid, decentralized detection of brain-derived neurotrophic factor (BDNF), one of the major neurotrophins (NTs) associated with neurological and psychiatric disorders in human saliva,” Raymundo-Pereira told us. “The salivary BDNF immunosensor strip is made on a screen-printed carbon electrode functionalized with carbon spherical shells (CSSs), polyethylenimine (PEI), and glutaraldehyde to enhance sensitivity.”
The BDNF immunosensor demonstrated high selectivity, reproducibility, robustness, stability, and long-term storage capability. At a cost of less than US$ 2.19 per unit, the disposable sensor also enabled rapid BDNF detection in saliva samples collected from healthy volunteers without interference from other salivary constituents.
“This device provides a rapid, efficient, cost-effective, and reliable method for the decentralized, noninvasive salivary analysis of BDNF, enabling broader applications in healthcare, wellness monitoring, and medical diagnostics related to the neurotrophin family of biomarkers,” Raymundo-Pereira told us. “The results were surprising mainly with regard to the wide BDNF detection range that the sensor was able to reliably track. Our biosensor showed the largest linear range detectable in the world.”
Raymundo-Pereira explained that their technology is exciting and forms part of the personalized care offering that will revolutionize how patients are helped and become increasingly proactive in their own health journey.
“Physicians will be able to use the sensor to aid in clinical diagnosis and also to manage the disease with drug treatments,” Raymundo-Pereira told us. « If the patient responds positively to the medications prescribed by the doctor, BDNF levels will tend to increase, otherwise, BDNF levels will remain low. This will lead to a decrease in side effects from the medications and will also reduce the abandonment of treatment by patients due to side effects.”