Hierarchical anatase TiO(2) nanoplates with tunable shell structure were developed as the novel planar scattering layer in dye-sensitized solar cells, showing improved cell performance due to the enhanced light harvesting capability.

A seeded heteroepitaxial growth of ZnO nanorods selectively on TiO 2 nanorod tips was achieved by restricting crystal growth on highly hydrophobic TiO 2 nanorod film surfaces. Intriguing light harvesting performance and efficient charge transport efficiency has been found, which suggest potential applications in photovoltaics and optoelectronics.Recently, branched nanowires (NWs) have attracted much interest due to their special tree-like structures offering greatly enhanced surface area and a direct conduction pathway for the rapid collection of photogenerated electrons, 1 and therefore promise very attractive potential applications in optoelectronics, photocatalysis, photovoltaics and sensing.1d,2 One of the key remaining issues in the field is the development of singlecrystal nanobranches with an epitaxial relation to the trunk to diminish the possibility of charge recombination during interparticle percolation. 3 Although there have been a few reports on the formation of branched NWs with different inorganic components fused together, 2b,4 these systems impose interfaces between materials with large lattice mismatch, with the formation of a large quantity of defects at grain boundaries as trapping sites, adversely affecting charge migration. 5ZnO and TiO 2 are the most investigated semiconductor materials for optoelectronic applications. ZnO is a direct band gap semiconductor with a wide band gap (E g = 3.37 eV) and large binding energy, high electrical conductivity and transparency in the visible region. After coupling with TiO 2 to form a ZnO-TiO 2 heterostructure, faster electron transport with reduced recombination loss can be expected because the electron mobility of ZnO is higher by 2-3 orders of magnitude than that of TiO 2 . 1c,6 In this communication, a heteroepitaxial growth of ZnO nanorods selectively on the tips of TiO 2 nanorods to form special dandelion-like heterostructures was achieved by restricting the seed planting and the following crystal growth on the film surface, based on the highly hydrophobic property of the TiO 2 nanorod film. Selective growth of metal or semiconductor dots on the secondary structure is of particular importance because of the strong coupling of electronic states and unusual properties. 7 This strategy is an effective and simple attempt for the selective growth of nanostructures with controlled density and location on the secondary component by taking advantage of the macroscopic wettability of materials. Arising from this special branched structure with heteroepitaxial interfaces, intriguing light harvesting performance and better electron transport efficiencies are exhibited, which imply potential applications in the fields of photovoltaics and optoelectronics.A key step enabling our design is to realize the selective deposition of a seed layer on the nanorod tips and prevent the precursor solution penetrating the grooves during the following crystal growth process. A hydrothermally derived rutile TiO 2 nanorod film 8 with rod length of B1.3 mm and diameter of B...

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A novel immobilized enzyme system supported by poly(acrylic acid/N,N'-methylene-bisacryl-amide) hydrogel microspheres was prepared. This system exhibited characteristics of reversible pH-triggered release. The morphology, size, and chemical structure were examined through optical microscopy, particle size analyzer, and Fourier transform infrared spectrometer. Immobilization and release features were further investigated under different conditions, including pH, time, and microsphere quantity. Results showed the microspheres were regularly spherical with 3.8 approximately 6.6 microm diameter. Loading efficiencies of bovine serum albumin immobilized by gel entrapment and adsorption methods were 93.9% and 56.2%, respectively. The pH-triggered protein release of the system occurred when medium pH was above 6.0, while it was hardly detected when medium pH was below 6.0. Release efficiencies of entrapped and adsorbed protein were 6.38% and 95.0%, respectively. Hence, adsorption method was used to immobilize trypsin. Loading efficiency of 77.2% was achieved at pH 4.0 in 1 h. Release efficiency of 91.6% was obtained under optimum pH catalysis condition set at 8.0 and trypsin was free in solutions with retention activity of 63.3%. And 51.5% of released trypsin could be reloaded in 10 min. The results indicate this kind of immobilized enzyme system offers a promising alternative for enzyme recovery in biotechnology.

Quantum-dots-tagged poly (styrene-acrylamide-acrylic acid) microspheres (QDsAAMs) were synthesized and modified with hydrazine hydrate through hydrazinolysis. Azidocarbonyl groups, which can be rapidly coupled with proteins under mild conditions, were introduced onto the surface of QDsAAM using azido reaction. Bovine serum albumin (BSA) was selected as model protein to be covalently immobilized on the azidocarbonyl QDsAAM. Instruments such as fluorescence microscope, optical microscope, confocal laser scanning microscope, UV-visible spectrometer, Fourier transform infrared spectrometer, size analyzer, and fluorescence spectrophotometer were used to characterize QDsAAM. Results showed that QDsAAM had a regular double-layer spherical shape and an average diameter of 11.2 microm. It also displayed high fluorescence intensity (lambda(ex)/lambda(em) = 250 nm/370 nm), which showed linearity with concentrations ranging from 3.0 x10(-3) to 90.0 x10(-3) g.L(-1). In addition, external factors such as pH and ionic strength exerted little influence on fluorescent characteristic. BSA immobilization indicated that QDsAAM with azidocarbonyl groups could be covalently coupled with BSA at the rate of 40 x10(-3) g/g (BSA/QDsAAM), while fluorescence linearity correlation was also found. This functional azidocarbonyl QDsAAM with sensitive fluorescence and active azidocarbonyl groups could be used as a promising fluorescent probe for quantitative detection, protein immobilization, and early rapid clinical diagnostics.