Achieving high-purity colloidal gold nanoprisms and their application as biosensing platforms

Gold nanoprisms with average edge size of ∼140 nm and thickness of ∼8 nm were achieved in high-purity (∼97%) by exploiting the electrostatic aggregation and shape effects through a modified seed-mediated approach. The proposed strategy lies in the dramatically different stability and aggregation potential between the produced gold nanoprisms and spherical gold nanoparticles, which can be modulated by varying the anion concentration in the reaction solution. Hence, the gold nanoprisms spontaneously aggregated into precipitate whereas most of the spherical ones were still kept in the solution. Moreover, this strategy is also flexible enough that ultra-small gold nanoprisms with average width less than 50 nm can be collected in good-purity. The structure and optical properties of these nanoprisms have been studied by TEM, SAED, XRD and UV–vis–NIR spectroscopy, respectively. These high-purity colloidal gold nanoprisms exhibit remarkably enhanced surface plasmon resonance (SPR) as well as strong near-infrared absorption. Furthermore, we have also investigated their potential for biosensing based on the sensitive changes of SPR band induced by the antibody–antigen recognition events. The experimental results clearly suggest that gold nanoprisms can be a promising nanostructured system for plasmonic sensor applications.

Graphical abstractHigh-purity colloidal gold nanoprisms (∼97%) were achieved by exploiting the electrostatic aggregation and shape effects through a seed-mediated, iodide ion- and CTABr-assisted synthetic system and used for biosensing in solution.Figure optionsDownload full-size imageDownload high-quality image (50 K)Download as PowerPoint slide