A potential-resolved ratiometric electrochemiluminescence immunosensor with N-(4-aminobutyl)-N-ethylisoluminol-functionalized sulfur quantum dots for sensitive detection of neuron-specific enolase.

BACKGROUND

Neuron-specific enolase (NSE) is a key tumor marker for distinguishing and diagnosing both small cell and non-small cell lung cancers. Therefore, developing a sensitive, accurate, rapid, and broadly linear strategy for detecting NSE in serum is crucial. Electrochemiluminescence (ECL) exhibits high sensitivity, a wide linear range, and low background signal. However, ECL can also produce false positives and false negatives, which can impact the accuracy of test results. To enhance the analytical performance of detection methods, exploring multiple potential-resolved ECL (PRECL) peaks or colors and developing novel ratio strategies are crucial.

RESULTS

The novel N-(4-aminobutyl)-N-ethylisoluminol (ABEI)-functionalized sulfur quantum dots (ABEI-SQDs) were synthesized through a room-temperature stirring reaction. With KSO as a co-reactant, ABEI-SQDs exhibited three ECL signals. Notably, ECL-1 displayed a peak at 675 nm, while both ECL-2 and ECL-3 featured peaks at 450 nm. These ECL peaks corresponded to peak potentials of -1.75, -0.64, and +0.70 V, which were attributed to ECL emissions from SQDs, ABEI, and ABEI within ABEI-SQDs, respectively. According to these properties, we developed a potential-resolved ratio ECL immunosensor for NSE detection. Under optimized experimental conditions, the sensor demonstrated a linear response to NSE concentrations ranging from 1 × 10 to 100 ng/mL, with a detection limit of 2.7 fg/mL (signal-to-noise ratio of 3).

SIGNIFICANCE

This sensor incorporated two emitters, ABEI and SQDs, within ABEI-SQDs for self-correction, thereby effectively mitigating errors and enhancing both the stability and accuracy of NSE detection. This study presents a novel approach for detecting NSE and identifying other biomarkers. Additionally, the research provides avenues for exploring new nanoluminescent groups with diverse PRECL luminescence properties, thereby expanding the applications of PRECL technology in biomarker detection.