Single-Base Detection of DNA with Simplified Steps on InGaN Quantum Wells

DNA testing is a powerful tool to evaluate an individual's risk for genetic disorders or certain illnesses. Completing the test quickly and accurately is the key to preventing many deadly diseases. However, the work is usually a tedious process as it entails multiple steps of molecular modification. To address the challenge, we present a simplified DNA detection tactic, skipping surface functionalization, fluorescent labeling, and probe immobilization. In addition, we show that a wide-field (9 × 9 μm²) submicron image of dilute DNA (1 × 10^-9 M) can be captured in a 3.5 min single laser exposure. The task is accomplished by surface-enhanced Raman spectroscopy (SERS) built with InGaN quantum wells covered by Al nanospheres. This unique biochip makes the nucleotide fully exposed to the SERS hot surface, catching the single-base DNA signal with single-molecule sensitivity.