A Paper‐Based Platform for Long‐Term Deposition of Nanoparticles with Exceptional Redispersibility, Stability, and Functionality

Abstract

Although nanoparticles (NPs) can be carefully engineered to have maximal stability and functionality desirable for use in diverse applications, they are generally not suitable for long‐term storage in solution. It is also difficult to store NPs in a dry state because dried NPs generally become aggregated and cannot easily be redispersed. Thus, a new strategy allowing long‐term storage of NPs with high stability, redispersibility, and functionality is highly demanded. By passivating the 13 nm gold nanoparticle (AuNP) surface with stabilizing agents and treating a paper substrate with both bovine serum albumin and sucrose after coating with a hydrophobic polyvinyl butyral layer, it is possible to fully redisperse (≈100%) dried AuNPs with colloidal stability comparable to that of as‐prepared AuNPs. Furthermore, AuNPs physically stabilized with polyvinylpyrrolidone can react with thiol‐containing compounds, such as 1,4‐dithiothreitol (DTT). Taking advantage of the oxidation reaction of hypochlorous acid with DTT, it is possible to demonstrate a paper‐based colorimetric sensor for detection of residual chlorine in water. Since this strategy is applicable to large‐sized AuNPs (30–90 nm), silver NPs, oleic acid‐capped magnetic NPs, and cetrimonium bromide‐passivated gold nanorods, it can be used for diverse NPs requiring long‐term storage for many applications.

Exceptional Mechanical Properties of Phase-Separation-Free Mo3Se3–-Chain-Reinforced Hydrogel Prepared by Polymer Wrapping Process

“…Several approaches have been suggested to modify the surfaces of nanomaterials through covalent and noncovalent modifications. 65 As the covalent modification has been reported to affect the inherent mechanical, electrical, and optical properties of the nanomaterials, 66 in this study, we focused on the noncovalent modification, which could successfully modify the Mo 3 Se 3 − nanowire surface without the formation of chemical bonds. Polymer wrapping of nanoparticles is one of the noncovalent modification methods effective to provide a nanoparticle surface chemically compatible with the polymer matrix.…”

Fabrication, Flow Control, and Applications of Microfluidic Paper-Based Analytical Devices

“…To detect the analytes in these potential areas, suitable transduction techniques need to be developed and optimized. These include colorimetric [135,136,137,138,139], electrochemical [140,141,142], chemiluminescence [143,144,145,146,147], electrochemiluminescence [148,149,150,151,152,153,154], and fluorescence [155,156,157,158,159,160] detection techniques. These techniques permit a simple, reliable, miniaturized, and cost-effective detection for various application areas.…”

“…It involves visually observing the color change during a reaction and using it for either qualitative or quantitative analysis with the help of the naked eye or a visual aid. Colorimetric detection offers the most simple and frequently used detection in the areas of protein analysis [36,161,162,163,164], drug analysis [23,165,166,167], and ion detection [40,42,139,168,169,170,171], covering all the fields from biomedical assay to environmental monitoring as well as food safety discernment (Figure 7A).…”

“…Detection techniques and recent applications of μPADs. ( A ) Colorimetric sensing of HOCl via AuNPs by controlling the concentration of dithiothreitol (reprinted with permission from ref [139]. Copyright 2019, WILEY).…”

Long-Term Stability Monitoring of Printed Proteins on Paper-Based Membranes

“…6,7 There are several careful studies of paper-based sensing membranes that provide a cheap and convenient option for virus/pollutant detection. 8−12 To date, a large number of novel paper-based sensing technologies, including nanoparticle-based and electronic-based sensors, have been developed to increase detection sensitivity. 13−16 However, many of these technologies require a significant amount of detection time, function only under certain storage conditions and are quite often expensive.…”