Colorimetric measurement of Fe3+ using a functional paper-based sensor based on catalytic oxidation of gold nanoparticles

Direct detection of Fe 3+ ions is of significant importance in view of both clinical and environmental applications. In the present study, we presented the construction of a paper-based colorimetric sensor by alternative modification of commercial cellulose paper with TiO 2 membrane as intermediate layer, hydrophobic/hydrophilic coating to obtain uniform diffusion, and decoration of –NH 2 and –SH groups for gold nanoparticles (AuNPs) immobilization. After optimization of fabrication and detection conditions, the colorimetric sensor showed a linear concentration-dependent colorimetric response (ΔG) in the presence of Fe 3+ concentrations ranging from 1.0 to 37   μM (R 2   >   0.98). The detection limit was calculated to be 0.85   μM (3δ) with good selectivity. Besides, the sensor also showed high resistance to AuNPs leaking in aqueous solutions, and demonstrated consistent measurement of Fe 3+ in serum samples. Those results suggested that as-prepared sensor strip is potential useful for Fe 3+ ion determination in clinical and environmental samples.