The design and formation of a linear assembly of gold nanorods using a biomolecular recognition system are described. Anti-mouse IgG was immobilized on the {111} end faces of gold nanorods through a thioctic acid containing a terminal carboxyl group. The biofunctionalized nanorods can be assembled with the desired length using mouse IgG for biorecognition and binding. The gold nanorods can be assembled to extended nanorod chains, which can be as long as 3 µm. These assembled nanostructures may be used as the precursors for future nanodevices.

In this review, we discuss recent advances of I–III–VI QDs with a major focus on synthesis and biomedical applications; advantages include low toxicity and fluorescent tuning in the biological window.

We report the effect of the initial Ag : In stoichiometry, capping ligand concentration, and reaction temperature on the optical properties (such as photoluminescence [PL] quantum yield, PL full width at half-maximum, and wavelength of maximum PL emission) of AgInS₂ quantum dots (QDs). The fabricated QDs exhibit excellent optical characteristics, including PL quantum yields of up to 22% and the appearance of an excitonic absorption peak. This is the first reported observation of such a well-defined exciton absorption feature in AgInS₂ QDs. Its appearance could indicate a relatively narrow size distribution or minimization of nonradiative recombination at the surface sites of the QDs. Moreover, we report one-pot two-step synthesis of highly luminescent AgInS₂–ZnS QDs by injection of ZnS precursors directly into the same reactor with existing AgInS₂ cores without any purification. In addition, to demonstrate their potential biomedical application, the AgInS₂–ZnS QDs were coated with poly(maleic anhydride-alt-1-octadecene) and further conjugated with folic acid for human liver carcinoma (HepG2) tumor cell labeling. The folate-receptor-mediated cellular uptake of the folic-acid-conjugated AgInS₂–ZnS QDs was confirmed by confocal imaging characterization. Additionally, the small dimensions and high solubility of the folic-acid-conjugated AgInS₂–ZnS QDs were also exploited in prefixed-cell staining; the QDs entered the complex cellular matrix and stained both the nucleoli and cytoplasm of HepG2 cells.