Development of novel poly(1,4-benzenedithiol) nanoparticles@AuNPs lateral flow immunochromatographic test strips†

In this study, we successfully developed a novel lateral flow immunochromatography (LFIA) strip that utilizes poly(1,4-benzenedithiol) (PBDT) nanoparticles loaded with gold nanoparticles (PBDT@AuNPs), characterized by a particle size of 147 nm and a spherical morphology, as labeling materials to enhance the sensitivity of colloidal gold. PBDT@AuNPs exhibit a higher loading capacity and molar extinction coefficient compared to traditional markers, with an approximately 22-fold increase in molar extinction coefficient relative to colloidal gold immunochromatography, significantly improving detection sensitivity. Cardiac troponin I (cTnI) was employed as a model to assess the detection efficiency and reliability of PBDT@AuNPs LFIA strips. A calibration curve was established using a four-parameter logistic function to fit the relationship between colloidal gold colorimetric strength and cTnI concentration, covering a range of 0.06 to 500 ng mL⁻¹, with a detection limit of 0.03 ng mL⁻¹ as calculated by the International Union of Pure and Applied Chemistry (IUPAC). A chemical comparison of various cTnI concentrations in human serum samples, conducted using Passing–Bablok regression, confirmed the equivalence of the PBDT@AuNPs LFIA strips with a commercial fluorescent cTnI LFIA kit, revealing no significant systematic or proportional bias. The spike recovery ranged from 91.92% to 108.70%, and the relative standard deviation (RSD) ranged from 5.29% to 5.85%, underscoring the high precision of the PBDT@AuNPs LFIA strips in quantifying cTnI in human serum samples.