Microfluidic electrochemical multiplex detection of bladder cancer DNA markers

- Porphyrin tagged DNA is shown to be a superior electrochemical sensor for DNA detection in microfluidic systems.
- DNA sequences associated with bladder cancer were reliably detected within 2 min.
- A microchannel device with 20 sensors simultaneously detects different DNA sequences with a detection limit of 250 fM.

Bladder cancer (BC) is one of the most difficult cancers to diagnose, and is reportedly the most expensive cancer to treat and monitor due to the lack of accurate chemical sensors; only limited methods are available, which usually are restricted to cytology and cystoscopy. Thus a system is urgently needed to detect biomarkers that give an unambiguous diagnosis on BC, as it currently is among the top five cancers occurring. Here we present a multi-sensor microchip array which efficiently detects three specific bladder cancer DNA markers simultaneously with a detection limit of 250 fM, which is well below the amount of DNA markers found in urine samples. The detection is based on the electrochemical response of a free-base porphyrin marker which is embedded in a molecular beacon; this system can easily be adapted to detect other DNA markers and developed for field applications, including point-of-care diagnostics, and gives an unambiguous readout within 20 min.