研究目的
Investigating the assembly rates and interparticle spacings of DNA-directed gold nanoparticle assemblies in solution using in-situ liquid-cell scanning transmission electron microscopy and fluorescence correlation spectroscopy.
研究成果
The study demonstrated that bridged DNA-directed gold nanoparticle assemblies formed larger aggregates more quickly than hybrid assemblies, with longer DNA linkage lengths accelerating the assembly process. The combined use of LC-STEM and FCS provided detailed information on assembly sizes, morphologies, and interparticle spacings, offering advantages over bulk characterization methods.
研究不足
The study was limited by the manual measurement of interparticle distances in LC-STEM images, which could be time-consuming and prone to human error. Additionally, the FCS technique, while rapid, may not be widely available for routine characterization.
1:Experimental Design and Method Selection
The study utilized in-situ liquid-cell scanning transmission electron microscopy (LC-STEM) and fluorescence correlation spectroscopy (FCS) to characterize DNA-directed gold nanoparticle assemblies. The LC-STEM provided high-resolution imaging of the assemblies in their native environment, while FCS measured the bulk volume fraction of large and small assemblies.
2:Sample Selection and Data Sources
Gold nanoparticles (Au NPs) functionalized with single-stranded DNA (ssDNA) were used to form two types of assemblies: hybrid and bridged. The hybrid assemblies involved two complementary ssDNA linkages, while the bridged assemblies involved a bridging ssDNA component that was double the length of the complementary ssDNA on the Au NPs.
3:List of Experimental Equipment and Materials
Equipment included an FEI Tecnai G2 F30 STEM, a Gatan Imaging Filter Tridiem, and a non-commercial microscope for FCS. Materials included maleimide-conjugated Au NPs, ssDNA sequences, Tris(2-carboxyethyl)phosphine (TCEP), and poly(ethylenimine) (PEI).
4:Experimental Procedures and Operational Workflow
Au NPs were functionalized with ssDNA and assembled into hybrid or bridged architectures. LC-STEM imaging was performed at 0, 24, 48, and 72 hours to measure interparticle distances. FCS measurements were taken to determine the diffusion coefficients of the assemblies.
5:Data Analysis Methods
Interparticle distances from LC-STEM images were measured manually. FCS data was analyzed using MATLAB to calculate diffusion coefficients and determine the fraction of large and small assemblies.
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