Surface wettability, measured via water contact angle (WCA) measurements, is an essential parameter in evaluating the characteristics of sensor surfaces in plasmonic biosensing, particularly in Kretschmann-based surface plasmon resonance (K-SPR). This study investigates plasma polymerized heptylamine (ppHA) coatings for enhancing Au K-SPR biosensors. The WCA results, ranging from 58° to 82°, confirm that a hydrophilic surface promotes biomolecule immobilization. The red shift of the SPR curve at 785 nm wavelength yields a refractive index sensitivity of 60°/RIU, with a good correlation coefficient (R² = 0.7584) between plasma power and WCA. The findings demonstrate that Au-ppHA coatings successfully optimize wettability and sensitivity, thereby improving SPR biosensor performance. Furthermore, the developed biosensor was successfully functionalized for creatinine detection, a key biomarker for kidney waste. The sensor demonstrated a high sensitivity of 1.1918 °/mM, confirming that ppHA coatings are an effective platform for developing high-performance K-SPR biosensors for medical diagnostics.
Jamil et al. (Mon,) studied this question.