Superhydrophobic titania nanoparticles for fabrication of paper-based analytical devices: An example of heavy metals assays

Abstract

A new strategy has been introduced to successfully fabricate the hydrophobic barriers of PADs by using organofluorine-modified superhydrophobic TiO2 NPs. Superhydrophobic TiO2-140 NPs with high-photoactivity can be converted to hydrophilicity by self-degradation of surface organic moieties under full spectrum light irradiation. Superhydrophobic TiO2-RT NPs with low-photoactivity exhibits good hydrophobic stability under light irradiation. Thus, combining these features, the PADs have been designed and constructed by photo-induced fabrication of hydrophobic barriers on the surface of the paper. To demonstrate the effectiveness of the constructed PADs, colorimetric detections have been displayed for Fe3+ and Ni2+ ions. The synchronous multi-component detections based on the “multi-channel” PADs and the intuitive detections based on the “chemical-symbol-style” PADs are rapid and feasible. A detection range of Fe3+ and Ni2+ ions based on the “circle-array” PAD is applicable and reliable in 0.2–6.0 mM and 0.4–4.0 mM, respectively. Thus, these results make it to be believed that this new strategy provides an alternative way to effectively construct the PADs.