| Highly photoluminescence （PL） semiconductor nanocrystals （NCs） have wideapplications in optoelectronic conversion, sensor, optical display, and biologicalimaging, etc, due to their quantum size effect. However, NCs prepared in aqueousoften exhibit low quantum yield （QY） and relatively wide size distribution. At thesame time, although the NCs can be directly used in biological imaging, the toxicityproblems have always been bothering people, which hinders their development.Therefore, investigating cytotoxic effect of aqueous NCs is very important. Thecytotoxicity of NCs mainly comes from cadmium ions(Cd2+) released from NCs,which can be reduced by preparing NCs with stable structure or modifying the surfaceof NCs. In this paper, the following work have been developed in order to decreasethe cytotoxicity of NCs:（1）The high quality stable CdHgTe quasi core/shell NCs were prepared viaone-step method. The PL property was further polished and the QY was improved to80%through the variance of the prepared conditions such as the ratio of ligand tometal ion, HTe-to metal ion, pH value and temperature. In addition, the cytotoxiceffects of CdHgTe NCs were systematically studied. The results showed that, forCd0.21Hg0.79Te NCs, its quasi core/shell structure was very stable and little cadmiumions was released. As a result, such NCs showed little cytotoxicity and would findapplications in tissue imaging or detection.（2）Modified NCs with polymers. CdTe NCs synthesized in aqueous media wereincorperated into three kinds of polymers: polyvinyl alcohol （PVA, neutral）, polydiallyl dimethyl ammonium chloride （PDDA, positive charged） and sodiumpolystyrene sulfonate （PSS, negative charged）, respectively. The experimental resultsshowed that QYs of NCs coating with PVA and PDDA decreased while QYs of NCscoating with PSS increased，and all of which can satisfy requirement of fluorencelabel. Further investigation was carried on the toxicity of NCs after coating withpolymer. When the concentration of NCs was10μg mL-1, NCs coating with PVA,PSS and PDDA exhibited lower toxicity than NCs, indicating their potentialapplications in biological imaging and detection. |
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