A facile route to CdTe nanoparticles and their use in bio-labelling

Abstract

A simple synthetic route to highly luminescent, water-soluble CdTe nanoparticles and their use in biological imaging is presented. The new synthetic pathway utilises a simply-prepared, watersoluble tellurium precursor which is easily handled and stored and the resulting growth processes are discussed.

A Facile One-Pot Synthesis of MSe (M = Cd or Zn) Nanoparticles Using Biopolymer as Passivating Agent

“…This suggested that the emission originated from a higher energy state than the band gap, in total contrast to other reports of CdSe nanomaterials. However similar observation has been reported recently for aqueous synthesis of cysteine-capped CdTe by Green et al, (2007).…”

“…All the particles emit in the blue region without any significant change in the emission maxima, which is at 406 nm. The observed blue shift in the emission spectra in relation to the absorption suggested that the emission originated from a higher energy state than the band gap (Green et al, 2007). This can be attributed to the shrinkage of the CdSe emitting core due to the interaction between the CdSe particles and the polymer.…”

“…The blue shift in the emission spectra and the appearance of the distinct excitonic shoulder at 5 and 24 h indicates the presence of smaller particles. This type of atypical optical spectra as the reaction time increases has been reported recently and was attributed to digestive ripening (Green et al, 2007). According to Green et al, digestive ripening is essentially the opposite of Ostwald ripening.…”

“…The emission maxima appeared at the same position through out the reaction time and are blue shifted in relation to the absorption band edge. This blue shift in the emission spectra in relation to the absorption has been attributed to emission from a higher energy state than the band gap (Green et al, 2007) due to the shrinkage of the CdSe emitting as a result of the interaction between the CdSe particles and the polymer. Since this atypical trend in the position of the absorption and emission spectra was reported for all the polymer capped CdSe nanoparticles under this synthetic route, it will be good to study the reaction earlier, i.e.…”

“…It usually involves the breaking of particles into smaller fragments or digestion of a layer at a time. Several factors such as ligands (Prasad et al2002), solvent (Hines & Scholes, 2003) and surfactant (Green et al, 2007;Samia et al, 2005), have been reported as the driving force for this mode of particle growth. The digestive ripening reported here is possibly a contribution from both the ligand and reaction medium.…”