Analyte-resolved magnetoplasmonic nanocomposite to enhance SPR signals and dual recognition strategy for detection of BNP in serum samples.

B-type natriuretic peptide (BNP) is a short peptide that is considered to be an important heart failure (HF)-related biomarker. Due to its low concentration in the blood and short half-life, the sensitive detection of BNP is a bottleneck for diagnosing patients at early stages of HF. In this paper, we report a facile surface plasmon resonance (SPR) sensor to measure BNP; the sensor is based on aptamer-functionalized Au nanoparticles (GNPs-Apt) and antibody-modified magnetoplasmonic nanoparticles (MNPs-Ab) to enable dual screening of BNP in complex environments. During sensing, BNP forms MNP-Ab/BNP/GNP-Apt nanoconjugates that can be rapidly separated from the complex sample by a magnet to avoid degradation within the analyte's half-life. The developed SPR biosensor shows high selectivity, a wide dynamic response range of BNP concentrations from 100 fg/mL to 10 ng/mL, and a low detection limit of 28.2 fg/mL (S/N = 3). Using the proposed sensor, BNP was successfully detected in clinical samples. Thus, the designed SPR biosensor provides a novel and sensitive sensing platform for BNP detection with potential applications in clinical practice.