In Situ-Synthesized Gold Nanostructures (issAu) to Minimize Storage Constraints in Sensing Applications

Nanoscale gold (Au) materials have garnered significant attention in chemical and biological analyses owing to their exceptional properties. However, their practical applications in sensing nanotechnologies are remarkably constrained by the inherent and universal drawbacks of nanomaterials. For instance, the poor stability of nanomaterials during storage substantially compromises the test repeatability and accuracy. To date, the lack of standardized protocols for the synthesis and storage of nanomaterials remains a critical barrier to the widespread applications of nanotechnologies. Without the storage, in situ-synthesized nanomaterials might offer a promising solution to overcome these storage-related challenges. In this perspective, Au nanostructures are classified into two categories: presynthesized Au (psAu) and in situ-synthesized Au nanostructures (issAu), respectively. Differing from psAu, issAu refers to protocols in which the preparation of Au nanostructures is simultaneously coupled with their concurrent functional applications. While extensive research has been conducted on psAu strategies, recent studies over the past decade have increasingly focused on issAu nanostructures. The issAu concept has exhibited boosted sensing responses and enhanced anti-interference in chemical and biological analysis. Moreover, issAu nanostructures work as intriguing signal probes, showing high potential in time-saving operation and improved selectivity and sensitivity. This perspective outlines the formation routes of issAu nanostructures and provides a comprehensive review of their unique properties and sensing applications. Additionally, a detailed comparison between psAu and issAu materials is correspondingly presented, underscoring the transformative potential of issAu nanostructures and inspiring broader applications of the in situ-synthesis concept for other vital nanomaterials.