This study describes the preparation of hydroxyapatite microspheres for local drugs delivery. The formation of the
hydroxyapatite microspheres was initiated by enzymatic decomposition of urea and accomplished by emulsification
process (water-in-oil). The microspheres obtained were sintered at 500°C. Scanning electron microscope (SEM)
indicated that the microspheres have various porous with random size, which maximizes the surface area. Cytotoxicity
was not observed after sintering. Osteoporosis drugs, alendronate and BMP-2, were loaded into HAp microspheres and
the releases of both molecules showed sustained releasing profiles.
This work reports the immobilization of monomeric, dimeric and trimer protein Gs onto silica magnetic nanoparticles for
self-oriented antibody immobilization. To achieve this, we initially prepared the silica-coated magnetic nanoparticle
having about 170 nm diameters. The surface of the silica coated magnetic nanoparticles was modified with 3-
aminopropyl-trimethoxysilane (APTMS) to chemically link to multimeric protein Gs. The conjugation of amino groups
on the SiO2-MNPs to cysteine tagged in multimeric protein Gs was performed using a sulfo-SMCC coupling procedure.
The binding efficiencies of monomer, dimer and trimer were 77 %, 67 % and 55 % respectively. However, the
efficiencies of antibody immobilization were 70 %, 83 % and 95 % for monomeric, dimeric and trimeric protein G, respectively. To prove the enhancement of accessibility by using multimeric protein G, FITC labeled goat-anti-mouse IgG was treated to mouse IgG immobilized magnetic silica nanoparticles through multimeric protein G. FITC labeled goat anti-mouse IgGs were more easily bound to mouse IgG immobilized by trimeric protein G than others. Finally protein G bound silica magnetic nanoparticles were utilized to develop highly sensitive immunoassay to detect hepatitis
B antigen.
Work presented here describes a simple and convenient process to highly efficient and direct DNA separation with
functionalized silica-coated magnetic nanoparticles. Iron oxide magnetic nanoparticles and silica-coated magnetic
nanoparticles were obtained uniformly and the silica coating thickness could be easily controlled in a range from 10 to
50 nm by changing the concentration of silica precursor (TEOS) including the controlled magnetic strength and particle
size. A change in the surface hydrophilicity on the nanoparticles was introduced by aminosilanization to enhance the
selective DNA separation resulting from electrostatic interaction. The efficiency of the DNA separation was explored via
the function of the amino-group numbers, particle size, the amount of the nanoparticles used, and the concentration of
NaCl salt.
This work describes the innovative development of high throughput human DNA purification process using the
molecular self-assembled mesoporous silica nanoparticles. The mesoporous silica nanoparticles were prepared by sol-gel
method and the formation of molecular self-assembled monolayers with functional groups was chemically demonstrated.
The surface modification of functional groups was performed with aminofunctionallized organic silanes on mesoporous
silica nanoparticles and the results of DNA separation was represented with electrophoresis images.
This work presents the highly controlled drug delivery system free from the burst release at
an initial stage and equipped with the capability of long term drug release. The nanoporous drug
releasing reservoir was combined with porous body resembling cancellous bone. The materials were
prepared by the integration of synthesized inorganic hydroxyapatite (HA) and the hybrid gels of
bicontinuous sponge-phased L3 silicate and thermo-responsive poly(N-isopropylacrylamide)
(L3-PNIPAm gels). The materials were designed to have the three dimensionally interconnected
heterogeneous porosity of macro- and mesoporosity, in which the HA has the macroporosity of 150μm to be impregnated the drug into the pores and the L3-PNIPAm gels have mesoporosity of 5 nm to
regulate the temperature sensitive drug-release through the pore channels and polymeric network,
respectively. Consequently, this bone-mimetic system gave the highly long term drug release over the
60 days without the burst release. The release rate could be controlled with the change of the HA and
PNIPAm composition ratios. The structural characterization was achieved by TEM, SEM, XRD,
Micro-Raman spectroscopy, BET, and the direct contact cytotoxicity test was also described.
This work described the development of high throughput human DNA purification process
with the amino-functionalized silica coated magnetic nanoparticles. The magnetic nanoparticles were
synthesized with average particle size of 9 nm and silica-coated magnetic nanoparticles were
obtained by controlling the coating thicknesses on magnetic nanoparticles. The silica coating
thickness could be uniform-sized in the diameter of 10-40 nm by a sol-gel approach. The surface
modification was performed with amino-functionalized organic silanes on silica coated magnetic
nanoparticles. The spectroscopic measurements such as a FT-IR(ATR-method) and Vibrational
Sample Magnetometer (VSM) were used to characterize the chemical structures and magnetic
strengths. To elucidate the relationship among the surface area, pore size distribution and reactivity of
the materials, XRD, TEM, BET and Zeta potential were used. The use of functionalized
self-assembled magnetic nanoparticles for human DNA separation process give a lot of advantages
rather than the conventional silica based process.
This work describes an innovative approach to preparation of the highly controlled drug delivery materials that involves a self-assembly process at the molecular level based upon the silicified L3 phase silicates and thermoresponsive PNIPAm integrated L3 phase silicates. The materials designed by the integration of thermosensitive polymer have been prepared and demonstrated for the highly controlled drug releasing system over a longer period of time due to their high degree of continuity and contigunity in 3-D interconnected porous structure. This approach is suitable for long term drug delivery systems with constant release in hard tissue engineering due to nanodiffusion mechanism. The structural characterization was achieved by TEM, SEM, SAXD, solid-state 29Si NMR, and BET.
This paper describes chemically functionalized mesoporous silica as a novel catalyst for the rapid hydrolysis of a phenyl ester. Work demonstrates a very simple and flexible approach to control surface reactivity on the nanometer scale using a self-assembled organic monolayer consisting of polar, (dihydroxyl, carboxyl, ethylene-diamine, and dihydroimidazole), and non-polar (isobutyl) groups. All five functional groups are an essential requirement in preparing an enzyme-like catalyst because of the synergistic effect and hydrophobic partitioning, which has been verified by a 13C CP- MAS solid-state NMR technique. Catalytic activities were obtained from the catalytic efficiency constant and specificity constant using Michaelis-Menten kinetics. Catalytic activities were close to those of a natural enzyme when 12% of the surface was covered by hydrophobic isobutyl silane. The rate of enzyme catalyzed activity was dependent on the energy of the transition state as defined in terms of an energy barrier derived from the relationship between transfer free energy and specificity constant.
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