An electrochemiluminescent-supramolecular approach to sarcosine detection for early diagnosis of prostate cancer.

Monitoring Prostate Cancer (PCa) biomarkers is an efficient way to the early diagnosis of this disease, since it improves therapeutic success rate and suppress PCa patients mortality: for this reason a powerful analytical technique such as Electrochemiluminescence (ECL) is already used for this application, but its widespread usability is still hampered by the high cost of commercial ECL equipment. We describe an innovative approach for the selective and sensitive detection of the PCa biomarker sarcosine, obtained by a synergistic ECL-supramolecular approach, in which the free base form of sarcosine acts as co-reagent in a Ru(bpy)3 2+-ECL process. We used magnetic micro-beads decorated with a supramolecular tetraphosphonate cavitand (Tiiii) for the selective capture of sarcosine hydrochloride in a complex matrix like urine. Sarcosine determination was then obtained with ECL measurements thanks to the complexation proprieties of Tiiii, with a protocol involving simple pH changes - to drive the capturing-releasing process of sarcosine from the receptor - and magnetic micro-beads technology. With this approach we were able to measure sarcosine in the μM-mM window, a concentration range that encompasses the diagnostic urinary value of sarcosine in healthy subject and PCa patients, respectively. These results indicate how this ECL-supramolecular approach is extremely promising for the detection of sarcosine and for PCa diagnosis and monitoring, and toward the development of portable and more affordable devices.