Characteristics of synthesized CdSe, CdSe/ZnS, and amphiphilic polymer-coated QDs (PQDs). (a) The absorbance and emission spectra of synthesized QDs. The green and red groups of lines represent absorbance (the curves from upper left to lower-middle part) and the photoluminescence (the curves with obvious protrusive shape) of the QDs at emission peaks of 526 and 644 nm, respectively. The solid line, dashed line, and dash-dot line indicate the core QDs, the core-shell structure QDs, and PQDs, respectively. (b) TEM image of CdSe cores. (c) TEM image of CdSe/ZnS core-shell prepared from CdSe. (d) TEM image of amphiphilic polymer-coated CdSe/ZnS core-shell QDs counterstained with 1% phosphotungstic acid solution. Insets in (b) and (c) showed the HRTEM images of the core and core-shell QD. (b,c,d represent red-colored QDs).