Voltammetric immunoassay based on MWCNTs@Nd(OH)₃-BSA-antibody platform for sensitive BSA detection

An electrochemical approach is presented based on multiwall carbon nanotubes (MWCNTs) and neodymium(III) hydroxide (Nd(OH)₃) nanoflakes for detection of bovine serum albumin (BSA). The materials were characterized morphologically (XRPD, SEM, and HR-TEM) and electrochemically (DPV, EIS). The MWCNTs@Nd(OH)₃ composite was used as support for bovine serum albumin polyclonal antibody (anti-BSA). After the antibody immobilization on the electrochemical platform and antigen/antibody binding time (optimum 60 min), the proposed approach shows a linear voltammetric response toward BSA concentration in the range 0.066 to 6.010 ng mL^-1 at maximum peak potential of 0.13 V (vs. Ag/AgCl). Limit of detection (LOD) and limit of quantification (LOQ) were 18 pg mL^-1 and 61 pg mL^-1, respectively. The precision of the method calculated as relative standard deviation (RSD) of five independent measurements was better 3%. The selectivity of the optimized method regarding structurally similar proteins (human serum albumin and human hemoglobin), ions (Na⁺, K⁺, Ca²⁺, and NO₂^-), or compounds (glucose, ascorbic acid, dopamine, uric acid, paracetamol, and glycine) was found to be satisfactory, with the current changes of less than 5% in the presence of up to 1 × 10⁵ times higher concentrations (depending on the compound) of the listed potential interfering compounds. Practical applicability of immunosensor for BSA determination in cow whey sample, with recovery values in the range 97 to 103%, shows that the developed method has high potential for precise and accurate detection of BSA, as well as exceptional miniaturization possibilities for on-site and equipment-free sensing.