Organic light-emitting diode-based fluorescence sensing system for DNA detection

Conventional fluorescence sensing equipment for disease detection is expensive and bulky, restricting access of patients to accurate diagnosis. Organic light-emitting diodes (OLEDs) have the potential to enable compact fluorescence sensing compatible with point-of-care (POC) testing. However, the limited brightness and broad emission spectra of OLEDs can be a challenge for achieving good sensitivity. Here, co-host microcavity OLEDs with narrowed spectra, high conductivity, and high brightness are developed for fluorescence sensing. The OLEDs are driven in pulsed mode for achieving higher brightness and stable light output. To sense the presence of single-stranded DNA (ssDNA), two complementary ssDNA labelled with Cyanine dyes – Cy3 (ssDNA-Cy3) or Cy5 (ssDNA-Cy5) are used to form a Förster resonance energy transfer (FRET) pair when the DNA hybridized. The dye-labelled DNA is then excited by the OLED at the Cy3 excitation wavelength, and the fluorescence is detected at the emission wavelength of Cy5. As a result, the device shows a very high sensitivity that can detect as low as 1 × 10⁻⁹ m of ssDNA-Cy5 in fetal bovine serum (FBS). This work shows a simple approach to highly sensitive fluorescence sensing with OLED light sources that is promising for use in POC diagnostics.