Controllable self-assembly of the DNA-linked gold nanoparticle (AuNP) architecture for in vivo biomedical applications remains a key challenge. Here, we describe the use of the programmed DNA tetrahedral structure to control the assembly of three different types of AuNPs (∼20, 10, and 5 nm) by organizing them into defined positioning and arrangement. A DNA-assembled “core–satellite” architecture is built by DNA sequencing where satellite AuNPs (10 and 5 nm) surround a central core AuNP (20 nm). The density and arrangement of the AuNP satellites around the core AuNP were controlled by tuning the size and amount of the DNA tetrahedron functionalized on the core AuNPs, resulting in strong electromagnetic field enhancement derived from hybridized plasmonic coupling effects. By conjugating with the Raman molecule, strong surface-enhanced Raman scattering photoacoustic imaging signals could be generated, which were able to image microRNA-21 and tumor tissues in vivo. These results provided an efficient strategy to build precision plasmonic superstructures in plasmonic-based bioanalysis and imaging.

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Surface plasmon resonance microscopy (SPRM) is a versatile technique for biosensing and imaging that facilitates high-sensitivity, label-free, real-time characterization. To date, SPR technology has been successfully commercialized and its performance has continued to improve. However, this method is inhibited by low spatial resolution and the inability to achieve single-molecule detection. In this report, we present an overview of SPRM research progress in the field of plasma imaging and sensing. A brief review of the technological advances in SPRM is outlined, as well as research progress in important applications. The combination of various new techniques with SPRM is emphasized. Finally, the current challenges and outlook of this technique are discussed.

Plasmonic optical tweezers with the ability to manipulate nano-sized particles or molecules that are beyond the diffraction limit have been developed rapidly in recent years. However, plasmonic heat generation always limits its applications in capturing particles or biomacromolecules that are vulnerable to high temperatures. Here, we propose nanorefrigerative tweezers based on a single refrigerative nanocrystal, which can form a nanometer-sized cold-spot via anti-Stokes fluorescence. Numerical simulations are performed to compute the temperature and velocity fields. The results show that thermo-osmosis and thermophoresis play major roles in nanoparticle manipulation, while natural convection in the nanoscale is negligible. This tweezing scheme not only offers a sub-diffraction-limit way to manipulate nano-objects but also avoids possible thermal damage to the trapped targets. Therefore, it will potentially become a powerful tool in biomedical and biosensing research studies.