The currently established DNA nanoprobes for detection of mycotoxin from beverages have been limited by complicated sample pretreatment and uncontrollable nanoparticle flocculation in complex systems. We develop a rapid colorimetric...

Anisotropic nanoparticles possess high sensitivity to environmental refractive index that is strongly dependent on their active facets. As a polyhedron exclusively enclosed by active facets, Au nano-rhombic dodecahedrons (AuNRDs) with...

Increasing the applications of disposable nanomaterials yet with potential environmental risk and the resulting nanowastes have become a problem of public concern worldwide. However, efficient recovery of useful materials from nanowastes is currently limited by their tiny size, high physicochemical activity, and unpredictable aggregation. We have developed a conceptually new strategy for recycling nanoprobes by alcoholic solvent “refreshing”. In specific, DNA-functionalized gold nanoparticles and nanorods are employed as colorimetric nanoprobes for Hg(II) and Ag(I) ions, respectively, both of which rely upon target-induced DNA terminal base pairing and the subsequent base pair stacking assembly of the nanoprobes. Upon the introduction of isopropanol to the “waste” aggregates, however, the DNAs are denaturalized to release heavy metal ions, leading to restoration of individual nanoprobes. The fine modulation of DNA hybridization not only affords sensitive detection but also addresses the recycling of the nanoprobes with high efficiency (>80%) while preserving the detection performance irrespective of the nanoprobe shape and surface-grafted DNA sequence. We further demonstrate the use of the recycled nanoprobes in the detection of Hg(II) species from salmon muscle tissue. With the generality of the recovering method and the combined features of the renewable nanoprobes, including high recycling efficiency and retained functionality, sustainable sensing nanomaterials are within reach.

DNA-functionalized gold nanoparticles (DNA-AuNPs) have become a popular science theme since their invention in 1990s. They impact our daily lives by playing key roles in rapidly identifying and quantifying important analytes, and are a well-suited chemistry course content for beginners of chemical research. While the salt-aging method represents the most commonly used for preparation of DNA-AuNPs, it is unfortunate that it necessitates elaborative operation and long-time (1–2 days) reaction. Introduction of a simple yet efficient functionalization approach to students may inspire their interest in DNA-AuNPs, giving a good start to their research careers. We carried out an investigation into fast (2 h) preparation of DNA-AuNPs by freezing, and demonstrate the applicability of the resultant DNA-AuNPs in colorimetric Hg2+ detection. Although students initially suspected a slower reaction in the frozen mixture, each student could smoothly accomplish the preparation of DNA-AuNPs eventually using the freezing method, with a large number of DNA functionalized per AuNP. Theoretical calculation of DNA number per AuNP and the detection application further convinced the students of the success in DNA functionalization of the AuNPs, providing a valuable research experience for the students. Given the robustness of the magic method for preparation of DNA-AuNPs, we have presented an exceptional example that improves students’ view of the chemical reaction, and inspires their creative thinking and interest in nanoprobes.