Solid-phase pink-to-purple chromatic strips utilizing gold probes and nanofibrous membranes combined system for lead (II) assaying

• Simple and low-cost electrospun nanofibers/nets (NFN) membrane-based chromatic strips were developed.
• NFN membranes are applied in interparticle distance-dependent chromatic system for the first time.
• NFN membranes possess unique composition, large specific surface areas, and distinctive weighted Steiner networks structure which facilitates the chromatic determination of Pb2+.
• Chromatic strips displayed a strong anti-disturbance to high concentrations of salts and proteins, with a naked-eye detection limit of 10 μg/dL.

Creating a sensitive and selective method that can provide simple, practical, and high throughput determination of lead ions (Pb2+) has proved extremely challenging. This work responds to this challenge by designing, fabricating, and evaluating a portable sensor strip for naked-eye chromatic assaying of trace amount of Pb2+. The sensor design is then realized utilizing electrospun nylon-6/polyvinylidene fluoride (N6/PVDF) nanofibers/nets (NFN) membranes assemble L-glutathione-conjugated Au nanoparticle probes (Au@GSH), which can aggregate to trigger a vivid color change of pink to purple upon incubation with Pb2+. Benefiting from large surface areas, high porosity, and Steiner tree networks structure of the NFN membranes, the strips exhibited excellent stability, rapid response (10 min), wide detection range (10–500 μg/dL) and low naked-eye detection limit of 10 μg/dL. Additionally, the sensing responses are visualized quantitatively by employing a chromatic framework that translates measured spectra into numeric color values directly related to color perception. Furthermore, the NFN-based strip displayed excellent selectivity to other possible metal cations. The result clearly demonstrated that this is a promising sensing system which could act as a first step toward remediation of lead poisoning in future.