An amplified voltammetric immunosensor for detection of porcine serum albumin using a self-standing nanohybrid composed of multi-walled carbon nanotubes, polyelectrolytes, and gold nanoparticles

[Display omitted] •A novel self-standing carbon-metal nanohybrid was developed for enhanced voltammetric immunosensing.•Polyelectrolytes enabled precise layer-by-layer assembly of the signal-amplified nanohybrid.•The nanohybrid exhibited excellent dispersion, aiding efficient antibody bioconjugation.•Remarkable sensitivity was achieved with a detection limit of 0.5 pg/mL for porcine serum albumin.•An improvement of two orders of magnitude over the single AuNP-based approach was demonstrated. Here, we introduce an innovative approach for signal amplification of a voltammetric immunosensor platform with nanoporous alumina (NPA) millirods to specifically target porcine serum albumin (PSA). A self-standing nanohybrid was constructed using a layer-by-layer assembly technique, which involved coating multi-walled carbon nanotube (MWCNTs) with polyelectrolytes (PEs) and subsequent attachment of multiple gold nanoparticles (AuNPs). The PEs improved dispersion of the MWCNTs and facilitated attachment to multiple AuNPs for enhanced bioconjugation with anti-PSA detection (α-PSAD) antibodies. The morphology of the nanohybrid was examined using field-emission scanning electron microscopy. The resulting MWCNT/PE/AuNP/α-PSAD-bioconjugated nanohybrid acted as an amplified signaling probe for the PSA-specific, NPA millirod-based voltammetric immunosensor. A current value recorded at +0.68 V (vs. Ag/AgCl reference electrode) in the voltammogram served as the analytical signal for quantification, thereby eliminating the need to analyze peak characteristics. Demonstrating remarkable sensitivity, the nanohybrid achieved a PSA detection limit of 0.5 pg/mL, surpassing the 50 pg/mL limit of an immunosensor using a single AuNP for signaling. The proposed nanohybrid offers a superior solution for highly sensitive detection of PSA in voltammetric immunosensor applications.