We have investigated the hybridization properties of DNA-gold nanoparticle conjugates and have discovered that the hybridization properties are dramatically affected by controlling various synthetic and environmental conditions. We have further demonstrated that moderate DNA loading instead of high loading per nanoparticle significantly enhances the hybridization rates of DNA-gold nanoparticle conjugates, which allows one to precisely design their hybridization properties to distinguish a single-nucleotide polymorphism (SNP). A diagnostic application for the colorimetric detection of an SNP associated with a mutation in the breast cancer gene BRCA1 has been carefully designed and demonstrated.

We employ a combinatorial library approach to control the shape of the silver nanostructures by regulating the structure of their seeds. Twenty-four polymers are investigated in detail with respect to their functionalities, chemical structures, molecular weights, and charges, each of which turns out to play significant roles in synthesizing high-quality silver nanoplates at room temperature in a fast manner. A mechanism depicting the exceptionally stable seed structures ‘stitched’ by polymer threads is proposed, which clearly explains the experimental observations.

We present the cooperative dehybridisation of DNA-gold nanoparticle conjugate (DNA-AuNP) assemblies induced by reduced salt concentration ([salt]), which can be precisely controlled by various conditions. The detection of Ag(+) based upon the [salt]-induced dehybridisation of DNA-AuNP assemblies is five times more sensitive than that achieved under conventional thermal melting conditions.

The recent synthetic development of a variety of nanoparticles has led to their widespread application in diagnostics and therapeutics. In particular, the controlled size and shape of nanoparticles precisely determine their unique chemical and physical properties, which is highly attractive for accurate analysis of given systems. In addition to efforts toward controlling the synthesis and properties of nanoparticles, the surface functionalization of nanoparticles with biomolecules has been intensively investigated since the mid-1990s. The complicated yet programmable properties of biomolecules have proved to substantially enhance and enrich the novel functions of nanoparticles to achieve "smart" nanoparticle materials. In this review, the advances in chemical functionalization of four types of representative nanoparticle with DNA and protein molecules in the past five years are critically reviewed, and their future trends are predicted.

We synthesized highly monodisperse gold microparticles (AuMPs) using a deep eutectic solvent (DES) which composed of choline chloride and malonic acid as both a reaction medium and structure-directing agent. These microparticles exhibit distinctive surface nanoroughness and highly defined diameters that can be precisely controlled over a range of a few micrometers under different reductive conditions. The internal and external structures of the particles are thoroughly investigated by electron microscopy, which is further analyzed in association with their optical properties. We also investigate the gold microparticle concentration-dependent catalytic property employing a reductive reaction of 4-nitrophenol to 4-aminopenol as a model system. Importantly, the gold microparticles are densely functionalized with DNA and reversibly assemble with DNA-gold nanoparticle conjugate probes for the colorimetric detection of target DNA sequences, demonstrating that these novel structures can be utilized as platforms that quickly regulate the optical properties of plasmonic nanoparticles for diagnostic applications.