Quantum Dot Biofunctionalization

We have shown the efficacy of Quantum Dots (qdots), nano-scale fluorescent particles made of semi-conductive material, as versatile biologically functional research tools. This functionality depends upon a series of chemical transformations that produce stable, aqueous, biomolecule-bound qdots with high quantum yield. We utilize the metal binding and chelating properties of the amino acid histidine to displace hydrophobic surface ligands and to phase-transfer qdots from organic to aqueous media. The intermediate binding strength of histidine to qdot surface facilitates its exchange with a variety of strongly binding thiolated biomolecules. Ligand profiles are subsequently characterized via FTIR, NMR, and gel electrophoresis. Negatively-charged aqueous qdots are shown to be taken-up and contained within phospholipid liposomes formed via several different protocols. Flexible liposome synthetic procedures allow intercalation of a number of moieties into liposomal membranes, including hydrophobic dyes and hydrophobic qdots. Possible implications for cellular delivery are discusse

Zn(Sn,Ge)N2 : a new double nitride tunable semiconductor family for LED and solar devices

National audienc

Prospective analysis of optoelectronic properties of ZnSnN2 for future tandem solar cells

International audienc

Prospective analysis of optoelectronic properties of ZnSnN2 for future tandem solar cells

International audienc

Standardized and reproducible measurement of decision-making in mice.

Progress in science requires standardized assays whose results can be readily shared, compared, and reproduced across laboratories. Reproducibility, however, has been a concern in neuroscience, particularly for measurements of mouse behavior. Here, we show that a standardized task to probe decision-making in mice produces reproducible results across multiple laboratories. We adopted a task for head-fixed mice that assays perceptual and value-based decision making, and we standardized training protocol and experimental hardware, software, and procedures. We trained 140 mice across seven laboratories in three countries, and we collected 5 million mouse choices into a publicly available database. Learning speed was variable across mice and laboratories, but once training was complete there were no significant differences in behavior across laboratories. Mice in different laboratories adopted similar reliance on visual stimuli, on past successes and failures, and on estimates of stimulus prior probability to guide their choices. These results reveal that a complex mouse behavior can be reproduced across multiple laboratories. They establish a standard for reproducible rodent behavior, and provide an unprecedented dataset and open-access tools to study decision-making in mice. More generally, they indicate a path toward achieving reproducibility in neuroscience through collaborative open-science approaches