Spatially Confined Chemistry:  Fabrication of Ge Quantum Dot Arrays

Heath, James R.; Williams, R. Stanley; Shiang, J. J.; Wind, Shalom J.; Chu, Junmei; D’Emic, C.; Chen, W.; Stanis, C.; Bucchignano, J.

doi:10.1021/jp951903v

Cited by 35 publications

(24 citation statements)

References 18 publications

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“…The properties of QDs result from quantum-size confinement, which occurs when metal and semiconductor particles are smaller than their exciton Bohr radii (about 1 to 5 nm) (2)(3)(4). Recent advances have resulted in the large-scale preparation of relatively monodisperse QDs (5-7), the characterization of their lattice structures (4), and the fabrication of QD arrays (8)(9)(10)(11)(12) and lightemitting diodes (13,14). For example, CdSe QDs passivated with a ZnS layer are strongly luminescent (35 to 50% quantum yield) at room temperature, and their emission wavelength can be tuned from the blue to the red wavelengths by changing the particle size (7,15).…”

Section: Quantum Dot Bioconjugates For Ultrasensitive Nonisotopic Detmentioning

confidence: 99%

Quantum Dot Bioconjugates for Ultrasensitive Nonisotopic Detection

Chan

Nie

1998

Science

6,924

4,262

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Highly luminescent semiconductor quantum dots (zinc sulfide-capped cadmium selenide) have been covalently coupled to biomolecules for use in ultrasensitive biological detection. In comparison with organic dyes such as rhodamine, this class of luminescent labels is 20 times as bright, 100 times as stable against photobleaching, and one-third as wide in spectral linewidth. These nanometer-sized conjugates are water-soluble and biocompatible. Quantum dots that were labeled with the protein transferrin underwent receptor-mediated endocytosis in cultured HeLa cells, and those dots that were labeled with immunomolecules recognized specific antibodies or antigens.

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Section: Quantum Dot Bioconjugates For Ultrasensitive Nonisotopic Detmentioning

confidence: 99%

Quantum Dot Bioconjugates for Ultrasensitive Nonisotopic Detection

Chan

Nie

1998

Science

6,924

4,262

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“…21 Ordered nanocrystals have already been assembled into superlattices by techniques such as colloidal crystallization, [54][55][56] macromolecule selfassembly, 11 57-59 complementary interactions, 48 60 61 and patterned etch pits. 62 Ordered biological structural arrays can serve as templates for the further construction of superlattices.…”

Section: General Approaches In Bottom Up Assembly Using Rna As Buildimentioning

confidence: 99%

RNA Nanotechnology: Engineering, Assembly and Applications in Detection, Gene Delivery and Therapy

Guo

2005

j nanosci nanotechnol

159

135

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Biological macromolecules including DNA, RNA, and proteins, have intrinsic features that make them potential building blocks for the bottom-up fabrication of nanodevices. RNA is unique in nanoscale fabrication due to its amazing diversity of function and structure. RNA molecules can be designed and manipulated with a level of simplicity characteristic of DNA while possessing versatility in structure and function similar to that of proteins. RNA molecules typically contain a large variety of single stranded loops suitable for inter-and intra-molecular interaction. These loops can serve as mounting dovetails obviating the need for external linking dowels in fabrication and assembly.The self-assembly of nanoparticles from RNA involves cooperative interaction of individual RNA molecules that spontaneously assemble in a predefined manner to form a larger two-or threedimensional structure. Within the realm of self-assembly there are two main categories, namely template and non-template. Template assembly involves interaction of RNA molecules under the influence of specific external sequence, forces, or spatial constraints such as RNA transcription, hybridization, replication, annealing, molding, or replicas. In contrast, non-template assembly involves formation of a larger structure by individual components without the influence of external forces. Examples of non-template assembly are ligation, chemical conjugation, covalent linkage, and loop/loop interaction of RNA, especially the formation of RNA multimeric complexes. The best characterized RNA multiplier and the first to be described in RNA nanotechnological application is the motor pRNA of bacteriophage phi29 which form dimers, trimers, and hexamers, via hand-in-hand interaction. phi29 pRNA can be redesigned to form a variety of structures and shapes including twins, tetramers, rods, triangles, and 3D arrays several microns in size via interaction of programmed helical regions and loops. 3D RNA array formation requires a defined nucleotide number for twisting and a palindromic sequence. Such arrays are unusually stable and resistant to a wide range of temperatures, salt concentrations, and pH. Both the therapeutic siRNA or ribozyme and a receptorbinding RNA aptamer or other ligands have been engineered into individual pRNAs. Individual chimeric RNA building blocks harboring siRNA or other therapeutic molecules have been fabricated subsequently into a trimer through hand-in-hand interaction of the engineered right and left interlocking RNA loops. The incubation of these particles containing the receptor-binding aptamer or other ligands results in the binding and co-entry of trivalent therapeutic particles into cells. Such particles were subsequently shown to modulate the apoptosis of cancer cells in both cell cultures and animal trials. The use of such antigen-free 20-40 nm particles holds promise for the repeated long-term treatment of chronic diseases. Other potentially useful RNA molecules that form multimers include HIV RNA that contain kissing loop to form di...

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“…[1][2][3][4][5][6][7][8][9][10][11][12][13][14][15][16] One interesting feature of nanoparticles is that their electronic, magnetic and optical properties can be dependent on particle size, shape, surface characteristics, and crystal structure. It is, therefore, possible in principle to manipulate the properties of the nanomaterials for specific applications of interest by carefully designing and controlling the parameters that affect their properties.…”

Section: Introductionmentioning

confidence: 99%

Synthesis, Optical Spectroscopy and Ultrafast Electron Dynamics of PbS Nanoparticles with Different Surface Capping

et al. 2000

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Lead sulfide, PbS, nanoparticles have been synthesized using a number of surface capping agents including poly(vinyl-alcohol) (PVA), poly(vinyl-pyrrolidone) PVP, gelatin, DNA, polystyrene (PS), and poly(methylmethacrylate) (PMMA). The electronic absorption spectra and particle shapes have been found to depend on the capping molecules used. An excitonic feature at 580 nm was observed for capping with PVA and DNA, while no such excitonic feature was observed for PVP, PS or PMMA. A weak excitonic feature was observed for gelatin. The particle shape varied from cubic, needle to spherical as controlled by the capping agents. For the DNA-capped PbS nanocrystals, HRTEM demonstrated the presence of oval crystals with a diameter of 3-8 nm. Powder X-ray diffraction of the PbS-DNA nanocrystals showed the characteristic peaks for PbS at 2.97, 3.43, and 2.10 Å. The XRD suggested the size of the nanoparticles to be approximately 4 nm. The dynamics of photoinduced electrons in PbS nanoparticles have been determined using femtosecond laser spectroscopy. For all the samples studied the electronic relaxation has been found to be very similar and follow a double exponential decay with time constants of 1.2 and 45 ps. The fast decay can be attributed to trapping from the conduction band to shallow traps or from shallow traps to deep traps while the slower decay is most likely due to electron-hole recombination mediated by a high density of surface trap states that lie within the band gap. The decay profiles are independent of particle size, shape, surface capping, probe wavelength, and excitation intensity. The results seem to indicate a high density of surface states, consistent with no detectable fluorescence signal at room temperature.

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Spatially Confined Chemistry: Fabrication of Ge Quantum Dot Arrays

Cited by 35 publications

References 18 publications

Quantum Dot Bioconjugates for Ultrasensitive Nonisotopic Detection

Quantum Dot Bioconjugates for Ultrasensitive Nonisotopic Detection

RNA Nanotechnology: Engineering, Assembly and Applications in Detection, Gene Delivery and Therapy

Synthesis, Optical Spectroscopy and Ultrafast Electron Dynamics of PbS Nanoparticles with Different Surface Capping

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