Early-Stage Lung Cancer Diagnosis by a Point-of-Care Electrochemical Aptamer-Based Sensor of NAP2 in Human Serum

The target neutrophil-activating peptide-2, NAP2, is a potential biomarker for early lung cancer diagnosis, whereas there are currently no precise techniques for differentiating NAP2 from its precursors. To overcome this difficulty, we created an electrochemical aptamer-based sensor (E-AB) consisting of the 33-mer aptamer domain, a 2-bp three-junction region, and two conductive signal reporter stems. Whereas E-AB-AT and E-AB-RAN sensors with two (AT)₆ or N₁₂ stems, respectively, were unable to distinguish between platelet basic protein (PBP) (94 aa) and NAP2 (70 aa). However, in contrast, the E-AB-GC sensor with two (GC)₆ stems could selectively detect NAP2 but hardly recorded PBP. Here, we developed an E-AB-GC point-of-care test (POCT) technique to detect NAP2 away from its precursors in 10 μL of human serum and provide concentration data in 5 min. Interestingly, serum NAP2 levels in human samples, as determined by the E-AB-GC sensor, were roughly 30-50% lower than those obtained by ELISA. Results also showed that E-AB-GC analysis of serum NAP2 in patients in stages I through IV revealed statistical significance and an excellent guiding function in the early diagnosis of lung cancer, particularly for patients in stage I cancer (p = 0.0054, area under the curve, 0.95). Importantly, this E-AB-GC POCT platform has shown potential as an on-site quick diagnostic tool, which can also be used to detect other lung cancer markers. Our research on the impacts of stem sequencing on sensing capabilities might assist in the future development of E-AB biomarker sensors.