Surfactant mediated optical properties of cytosine capped CdSe quantum dots

This letter demonstrates the use of one of the nucleobases, 'cytosine' as a new capping agent in controlling the size of the nanoparticles. A size dependent blue shift in optical absorption with enhanced luminescence is observed. Since the calculated density of states do not show any change in the band gap of as-prepared quantum dots after capping. the observed blue shift of the absorption peak can solely be attributed to the so-called size-effect whereas the enhancement in luminescence to surfactant mediated defect passivation. It is expected that the observed properties of the cytosine capped CdSe quantum dots would facilitate a better bio-compatibility of tailor-made nanoparticles for bio-imaging applications. (C) 2010 Elsevier B.V. All rights reserved.