Heterostructural core–shell quantum dots (hetero-QDs) have garnered a copious amount of research effort for not only scientific advances but also a range of technological applications. Particularly, controlling the heteroshell deposition, which in turn determines the particle morphology, is vital in regulating the photophysical properties and the application potential of the hetero-QDs. In this work, we present the first report on a synthesis of pyramidal shaped (i.e., hexagonal pyramid, HP, and hexagonal bipyramid, HBP) CdSe-CdS hetero-QDs with high morphological uniformity and epitaxial crystallinity through a two-step shell growth method. The stabilization of the exposed (0002) and {101̅1} facets by octadecylphosphonic acid and oleic acid ligands, respectively, is the key for the formation of pyramidal particle shapes. High photoluminescence quantum yield (94%, HP-QDs and 73%, HBP-QDs), minimal inhomogeneous PL line width broadening, and significantly suppressed single-QD blinking are observed. Specifically, the “giant” HBP-QDs showed an average “On” time fraction of 96% with more than 50% of measured particles completely nonblinking. Additionally, high multiexciton emission, prolonged ensemble and single-QD PL lifetimes as compared to their spherical counterparts are also reported. Finally, the HBP-QDs have been successfully transferred into an aqueous solution without aggregation. High cellular uptakes associated with low cytotoxicity render these water-soluble HBP-QDs an excellent candidate for intracellular imaging and labeling.

This review discusses various synthetic methods of Au–Cu alloy nanoparticles and their plasmonic, catalytic and photothermal properties.

The forms of inorganic mercury (HgII) taken up and methylated by bacteria in sediments still remain largely unknown. From pure cultures studies, it has been suggested that dissolved organic matter (DOM) may facilitate the uptake either by acting as a shuttle molecule, transporting the HgII atom to divalent metal transporters, or by binding HgII and then being transported into the cell as a carbon source. Enhanced availability of Hg complexed to DOM has however not yet been demonstrated in natural systems. Here, we show that HgII complexed with DOM of marine origin was up to 2.7 times more available for methylation in sediments than HgII added as a dissolved inorganic complex (HgII(aq)). We argue that the DOM used to complex HgII directly facilitated the bacterial uptake of HgII whereas the inorganic dissolved HgII-complex adsorbed to the sediment matrix before forming bioavailable dissolved HgII complexes. We further demonstrate that differences in net methylation in sediments with high and low organic carbon content may be explained by differences in the availability of carbon to stimulate the activity of Hg methylating bacteria rather than, as previously proposed, be due to differences in HgII binding capacities between sediments.

In this work, we develop a simple method to produce highly uniform localized surface plasmon resonance (LSPR) substrates based on self-assembly of colloidal gold nanoparticles onto pretreated glass substrates. The LSPR wavelength of the gold nanoparticle arrays is blue-shifted from that of the gold nanoparticles in solution and the single gold nanoparticles on glass substrate. The LSPR width is narrower than that of the single gold nanoparticles. The blue-shifted LSPR is due to the long-range dipole coupling in the gold nanoparticle random arrays indicated from simulations using the T-matrix method. In addition to the popularly used LSPR wavelength dependence on the dielectric environment, we have found that the LSPR width of the gold nanoparticle random arrays is also sensitive to the change in the dielectric environment. The LSPR substrates are reproducible, uniform, and robust with potential applications in LSPR sensing and imaging.

This work reports a general wet-chemistry method to produce Au–Cu–X (X = Pt, Pd, and Ag) trimetallic nanorods using galvanic replacement reaction with Au–Cu nanorods as the templates.