CdS quantum dots

Peter LM, Rdey DJ, TuU EJ, Wijayantha KGU (2002) Photosensitization of nanocrystalline Ti02 by self-assembled layers of CdS quantum dots. Chem Commun 10 1030-1031... 

B. Mukhopadhyay, M. B. Martins, R. Karamanska, D. A. Russell, and R. A. Field, Bacterial detection using carbohydrate-functionalised CdS quantum dots A model study exploiting E. coli recognition of mannosides, Tetrahedron Lett., 50 (2009) 886-889. 

Nanomaterials can also be applied to glucose biosensors to enhance the properties of the sensors and, therefore, can lead to smaller sensors with higher signal outputs. Carbon nanotubes have been incorporated in previously developed sensors and seen to increase the peak currents observed by threefold.89 Platinum nanoparticles and single-wall carbon nanotubes have been used in combination to increase sensitivity and stability of the sensor.90,91 CdS quantum dots have also been shown to improve electron transfer from glucose oxidase to the electrode.92,93 Yamato et al. dispersed palladium particles in a polypyrrole/sulfated poly(beta-hydro-xyethers) and obtained an electrode response at 400 mV, compared to 650 mV, at a conventional platinum electrode.94... 

In a representative work, Chen and Rosenzweig34 were able to alter the selectivity of CdS nanoparticles to respond either to Zn2+ or Cu2+ simply by changing the capping layer. They showed that, while polyphosphate-capped CdS QDs responded to almost all mono- and divalent metal cations (thus showing no ion selectivity), luminescence emission from thioglycerol-capped CdS QDs was quenched only by Cu2+ and Fe3+, but was not affected by other ions at similar concentrations. On the other hand, the luminescence emission of L-cysteine-capped CdS quantum dots was enhanced in the presence of zinc ions, but was not affected by cations like Cu2+, Ca2+, and Mg2+. Using this set of QD probes, the authors described the selective detection of zinc and copper in physiological buffered samples, with detection limits of 0.8 pM and 0.1 p,M for Zn2+ and Cu2+, respectively. This was claimed to be the first use of semiconductor nanocrystals as ion probes in aqueous samples. 

Rajh, T. Micic, O. I. Lawless, D. Serpone, N. Semiconductor photophysics. 7. Photoluminescence and picosecondcharge carrier dynamics in CdS quantum dots confined in a silicate glass, J. Phys. Chem. 1992, 96, 4633. 

Kamalov, V. F. Little, R. Logunov, S. L. El-Sayed, M. A. Picosecond electronic relaxation in CdS/HgS/CdS quantum dot quantum well semiconductor nanoparticles, J. Phys. Chem. 1996, 100, 6381. 

Semiconductor nanoclusters (quantum dots) possess chemical and physical properties that differ substantially from those of the analogous bulk solids [36-38]. Quantum dots have been synthesized using hosts such as zeolites [39], porous glass [40], micelles [41], membranes [42], and anionic polymers [43]. The synthesis and characterization of CdS quantum dots in dendrimer hosts have been studied [44-48]. Here, two PAMAM dendrimers are used one is G3.5 with surface carboxyl group and the other is G4 with surface amino group. Mixing solutions of Cd2+ and S2 in pure methanol result in a yellow precipitate of... 

Fig. 3.8. TEM picture of CdS quantum dots capped with octadecanethiol molecules and phase transferred into petroleum ether. The arrows in the figure identify some triangular shaped CdS nanoparticles.

Other than AUNPs, Quantum dots have also been employed in the development of pesticide sensors. Li et al. have synthesized Poly (N-vinyl-2-pyrrolione) (PVP)-capped CdS quantum dots (QCdS-PVP) from CdC and Na2S in the presence of PVP [37], AChE was immobilized onto this QCdS-PVP matrix incorporated GCE surface. The resulting GCE/ QCdS-PVP/AChE sensor was used for the detection of OP pesticides, such as trichlorfon. The enzyme immobilization procedure was described as follows. About 3 ml of QCdS-PVP was deposited on the surface of the GCE and dried in air. Then 3 ml of 0.5 mg ml"1 AChE along with 2.5% GA was deposited on the surface of the QCdS-PVP modified GCE and dried for 1 h at room temperature. TEM results show that, the QCdS-PVP particles were homogeneously distributed and they possess an average size of 2-4 nm (Fig. 9). 

Tachibana Y., Akiyama H. Y., Ohtsuka Y., Torimoto T. and Kuwabata S. (2007), CdS quantum dots sensitized Ti02 sandwich type photoelectrochemical solar cells , Chem. Lett. 36, 88-89. 

Lawless D. (1993), Photophysical studies on ultra-small semiconductor particles CdS quantum dots, doped and undoped Ti02 and silver halides , PhD Thesis, Concordia University, Montreal, Canada. 

A description is proposed for luminescence decay in Mn-doped CdS quantum dots based on a model implying radiative and dispersive n on-radiative decay of excited impurity ions. The model provides an adequate explanation of experimental photoluminescence kinetics in CdS Mn nanociystals. The excited state lifetime evaluated for Mn ions is about 2.3 ms and close to the bulk case. 

Figure 8.7 Captured PbS and CdS quantum dots attached to aptamer-bound proteins are dissolved and detected by electrochemical stripping analysis. The position and size of the corresponding metal peaks (cadmium and lead) reflect the identity of a concentration of the corresponding protein. [From Hansen et al. (2006).]...

Gope, G. Chakdar, D. Avasthi, D.K. Panl, M. Nath, S.S. 2008. Effect of swift heavy ion on CdS quantum dots embedded in PVA matrix and their applications. In Laudon, M. Romanowicz, B. (Eds.). NSTI Nanotech, Nanotechnology Conference andTrade Show, Technical Proceedings, June 1-5, 2008, Boston, MA, Vol. 3, pp. 43 5. 

Chen, Y. and Rosenzweig, Z. 2002. Luminescent CdS quantum dots as selective ion probes. Anal. Chem. 74 5132-5138. 

Esteves ACC, Bombalski L, Trindade T, et al. (2007) Polymer grafting from Cds quantum dots via AGET ATRP in miniemulsion. Small 3 1230-1236... 

Fig. 37 (a) Synthesis of hybrid core-sheU particles doped with CdS quantum dots. Reprinted from [321] with permission of Wiley-VCH. (b) TEM photo of the core microgels. Scale bar. 50 nm. Reprinted from [182] with permission of the American Chemical Society... 

The effects of poly(vinyl alcohol) and CdS quantum dots on the photoluminescence of PPV nanofibers have been assessed [90]. The nanofiber composites were fabricated by coupling a self-assembly method and an electrospinning method. 

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