A novel inorganic-organic hybrid polymer microspheres were facilely synthesised by distillation-precipitation
polymerization in absence of any stabilizer or surfcant. The process were conducted with [3-(Methacryloyloxy) propyl]
trimethoxysilan (MPS) as monomer, divinyl benzene (DVB) as cross linking agent and azobisisobutyronitrile (AIBN) as
initator in acetonitrile. A series of silica nanoparticles were prepared in accordance with the volume ratio of MPS, which
was varied in the range of 10% to 50%. However, there is no microspheres obtained while the ratio up to 50%. Products
were charactered by transmission electron micrograph (TEM) and fourier transform infrared spectroscopy (FTIR). We
may infer it from the constructional formular and FTIR graph that there were silicon hydroxyl remained in the
microsphere surface.
Polymer microspheres with functional groups are attractive for a wide number of applications, including supporting phases for separation science, biomedical devices, casting additives and controlled release reservoirs. In this paper, Poly(divinylbenzene-co-4-vinylpyridine)(Ploy(DVB-co-4-Vpy)) microspheres with functional pyridyl was prepared by distillation-precipitation polymerization and precipitation polymerization separately when 2,2'-Azobisisobutyronitrile (AIBN) as initiator in net acetonitrile. The feature of microspheres was characterized by TEM while the loading capacity of nitrogen on microspheres' surface and the hydrophilicity were measured by back titration and contact angle measurement. Under the same crosslinking degree, the microspheres prepared by distillation-precipitation polymerization had better feature, smoother surface, more functional groups and better hydrophilicity but lower yields than the ones prepared by precipitation polymerization.
A novel and sensitive electrochemical DNA biosensor based on multi-walled carbon nanotubes functionalized with a thio group (MWNTs-SH) and gold nanoparticles (GNPs) for covalent DNA immobilization and enhanced hybridization detection is described. The key step for developing this novel DNA biosensor is to cut the pristine MWNT into short and generate lots of active sites simultaneously. With this approach, the target DNA could be quantified in a linear range
from 8.5×10-10 to 1.5×10-5 mol/L, with a detection limit of 1.67×10-11 mol/L by 3σ.
KEYWORDS: Quantum dots, Luminescence, Nanocrystals, System on a chip, Americium, Fluorescence resonance energy transfer, Quantum efficiency, Biosensing, Nanoparticles, Tellurium
Concerns on quantum dots (QDs) have been continuously increasing because of their advantages on photophysical
properties. Water soluble CdTe/CdS core-shell and CdTe/CdS/ZnS multi-layer QDs were synthysized with
mercaptopropanoic acid (MPA) as stabilizer in aqueous phase in the current research. The obtained QDs were
characterized with fluorescence spectrum (FS), and quantum yields (QYs) was calculated base on the resulting data from
FS. Comparing with CdTe core, red-shift of maximum emission wavelength (MEW) of CdTe/CdS was observed, which
indicated the growth of QDs size. To obtain high QYs of CdTe/CdS core-shell QDs, several methods and different
reaction conditions were investigated and discussed, such as dependence of Cd2+ concentration, dependence of pH,
influence of S2-:Te2-, and effect of Cd2+:S2- etc. Among all of discussed methods, QYs of core-shell CdTe/CdS is
generally degressive with refluxing time elapsing. The best QYs of 79.8% can be achieved when pH was set at 8.5,
Cd2+:S2-=1:0.1 (mol ratio). Moreover, CdTe/CdS/ZnS multi-layer QDs was prepared, and results via FS indicated a
further red-shift from 554 nm to 646 nm comparing with CdTe/CdS QDs, but QYs decreased to 14.0%. QDs currently
discussed in this research are easily synthesized, and safe to organism, i.e. biocompatible. They will be useful in
applications of biolabeling, imaging, and biosensing based on fluorescence resonance energy transfer (FRET).
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