Colorimetric sensor strips for lead (II) assay utilizing nanogold probes immobilized polyamide-6/nitrocellulose nano-fibers/nets

A facile, ultrasensitive, reproductive and selective sensor strip utilizing electrospun polyamide-6/nitrocellulose (PA-6/NC) nano-fibers/nets (NFN) membranes assemble bovine serum albumin decorated Au nanoparticles (BAu probe) for naked-eye colorimetric assay of Pb 2+ has successfully prepared through dual-component alternate distribution multifluidic electrospinning technique . Benefiting from the extremely large specific surface areas and high porosity of NFN membranes, the stability of BAu probe dramatically increased and the strips presented a significant absorbance decreasing band at 546   nm which induce the visual color changes from deep pink to white after incubated in Pb 2+ liquor with a low detection limit of 0.2   μM without any assistance of equipment. Upon exposure to a series of metal ions , only Pb 2+ could induce a pink-to-white color change, which clearly exhibited that BAu probe immobilized PA-6/NC membranes could act as highly selective strips to detect Pb 2+ with little interference from other metal ions. Additionally, the colorimetric responses are represented in visualized quantitative by calculated color difference from L ⁎ a ⁎ b ⁎ coordinates which are presented with lightness and chrome values. Furthermore, the sensitivity of NFN membrane-based strips is much higher than that of film-based ones. The results indicate that this promising cost-effective sensing system could potentially allow for assaying of Pb 2+ in human urine or blood as preliminary screening of lead poisoning.