This paper reports a new optical probe for detect dalapon. We have synthesized the luminescent and stable CdTe quantum dots(QDs) capped with calix[6]arene(C[6]/SiO2/CdTe) via the sol-gel technique in aqueous media. These hybrid organic-inorganic compounds are characterized by IR spectroscopy, ultraviolet-visible spectroscopy (UV-vis), transmission electron microscopy (TEM), and fluorescence. We found that the C[6]/SiO2/CdTe were more stable and had higher fluorescence than the SiO2/CdTe nanoparticles (NPs). The C[6]/SiO2/CdTe show selectivity and sensitivity to dalapon via significant fluorescence intensity decrease. It can be ascribed to the Stern-Volmer equation. Under the optimal conditions, the relative fluorescent intensity was decreased linearly with increasing dalapon concentration in the range of 1.0–25.0 nmol/L with a detection limit of 0.262 nmol/L of dalapon. The possible underlying mechanism is discussed by Langmuir binding isotherm. 相似文献
SiO2–SO3H, with a surface area of 115 m2/g and pore volume of 0.38 cm3g−1, and 1.32 mmol H+/g was used as a 20% w/w catalyst for the preparation of methyl salicylate (wintergreen oil or MS) from acetylsalicylic acid (ASA). A 94% conversion was achieved in a microwave reactor over 40 min at 120 °C in MeOH. The resulting crude product was purified by flash chromatography. The catalyst could be reused three times. 相似文献
Mesoporous silica nanoparticles (MSNPs) have been widely used as drug carriers for stimuli‐responsive drug delivery. Herein, a catalysis screening technique was adopted for analyzing the effects of chain length, terminal group, and density of disulfide‐appended functional ligands on the surface of MSNPs on drug‐loading capacity and glutathione‐triggered drug‐release kinetics. The ligand with an intermediate length (5 carbon atoms) and a bulky terminal group (cyclohexyl) that complexes with theβ‐cyclodextrin ring showed the highest drug loading capacity as well as good release kinetics. In addition, decreasing the surface coverage of the functional ligands led to an enhancement in drug release. In vitro drug‐delivery experiments on a melanoma cell line (B16‐F10) by using the functionalized MSNPs further supported the conclusion. The results obtained may serve as a general guide for developing more effective MSNP systems for drug delivery. 相似文献
Chitosan is a non-toxic biological material, but chitosan is insoluble in water, which hinders the development and utilization of chitosan. Chitosan derivatives N-2-Hydroxypropyl trimethyl ammonium chloride (N-2-HACC) and carboxymethyl chitosan (CMCS) with good water solubility were synthesized by our laboratory. In this study, we synthesized mesoporous SiO2 nanoparticles by the emulsion, and then the mesoporous SiO2 nanoparticles were modified with γ-aminopropyltriethoxysilane to synthesize aminated mesoporous SiO2 nanoparticles; CMCS and N-2-HACC was used to cross-link the aminated mesoporous SiO2 nanoparticles to construct SiO2@CMCS-N-2-HACC nanoparticles. Because the aminated mesoporous SiO2 nanoparticles with positively charged can react with the mucous membranes, the virus enters the body mainly through mucous membranes, so Newcastle disease virus (NDV) was selected as the model drug to evaluate the performance of the SiO2@CMCS-N-2-HACC nanoparticles. We prepared the SiO2@CMCS-N-2-HACC nanoparticles loaded with inactivated NDV (NDV/SiO2@CMCS-N-2-HACC). The SiO2@CMCS-N-2-HACC nanoparticles as delivery carrier had high loading capacity, low cytotoxicity, good acid resistance and bile resistance and enteric solubility, and the structure of NDV protein encapsulated in the nano vaccine was not destroyed. In addition, the SiO2@CMCS-N-2-HACC nanoparticles could sustain slowly released NDV. Therefore, the SiO2@CMCS-N-2-HACC nanoparticles have the potential to be served as delivery vehicle for vaccine and/or drug. 相似文献
Abstract An eco-friendly and mild protocol for trimethylsilyl protection of alcohols over phosphorus pentoxide supported on silica gel using hexamethyldisilazane has been described. Solvent-free and ambient reaction conditions, easy workup, short reaction times, excellent yields, and reusability of the catalyst are the noticeable features of this methodology. GRAPHICAL ABSTRACT 相似文献
Poly(dimethylsiloxane) (PDMS) modified silica xerogels were prepared by two-step acid/base catalyzed sol-gel process. By keeping the acid amount and hydrolysis period in acidic environment fixed, and adding different amounts of base to the sol afterwards, attempts had been made to study the effect of the different amounts of base catalyst on the micro-structure and physical properties of the prepared ORMOSILs. DTA, SEM, BET, FTIR were performed to characterize the derived specimens. The microstructure and physical properties are greatly influenced by the amount of base added to the sol. With increasing base content the crystallite size and porosity increase and the pore size distribution takes a broad spectrum. Whereas, the glass transition temperature seems to decrease with increasing of base catalyst amount. This is explained in terms of the change in the relative amounts of hydrolysis and condensation reactions due to the addition of different amount of base catalyst, which predominantly influences the condensation reactions. The results are reported in this communication along with possible explanations behind the observations. 相似文献
The sol-gel technology has been applied to obtain SiO2 spheres of submicron size. The spheres have been doped with YAG:Nd3+ nanocrystallites. The nanocrystallites have been obtained from aqueous solutions of citric acid, yttrium, aluminum and neodymium chlorides. The obtained gels have been heated up to 800°C. Emission spectra as well as the excited state lifetimes have been measured at room and liquid nitrogen temperatures. The structural characterization has been performed by means of transmission and scanning electron microscopies (TEM, SEM) and powder diffraction (XRD) measurements. We have observed that the YAG:Nd3+ nanocrystallites demonstrate pronounced dependence of the emission intensities on the excitation power as compared to the YAG:Nd3+ crystallites embedded into the submicron SiO2 spheres. The results suggest that silica spheres/YAG:Nd3+ composites are expected to be good hosts for microlaser systems. 相似文献
Two families of hybrid organic-inorganic composites exhibiting Li+ ionic conduction (ORMOLYTES) have been prepared by the sol-gel process. The first family, prepared from a mixture of 3-isocyanatopropyltriethoxysilane, O,O Bis (2-aminopropyl)-polyethyleneglycol (or O,O Bis (2-aminopropyl)-polypropyleneglycol) and lithium salt, presents chemical bonds between the organic and the inorganic phase and an ionic conductivity higher than 10-4 S m-1 at room temperature. Their properties have been related to their structure using liquid state NMR measurements of 7Li between -100°C and +100°C and the DMTA technique. In the second family, prepared by ultrasonic method from a mixture of tetraethoxysilane (TEOS), polyethyleneglycol (PEG) and lithium salt, the organic and inorganic phases are not chemically bonded. Ionic conductivity has been studied as a function of the polymer chain length and concentration. Values of up to 10-2 S m-1 at room temperature have been obtained (with a silica-PEG300 system, PEG/TEOS = 40% in weight). Again, structure was investigated by liquid state 7Li NMR measurements. 相似文献
Optical and structural properties of coumarin-4 dye-doped SiO2-PDMS xerogels synthesized by acid catalyzed (one-step) and acid-base catalyzed (two-step) sol-gel routes with varying pH (0.6 to 7) and dye content ( 5 × 10–4 to 5 × 10–2 mole) are reported. Spectroscopic methods such as photo-luminescence, FT-IR and FT-Raman were used for characterizations. The acid catalyzed xerogels prepared with pH < 2.5 exhibited two fluorescence peaks, I at 390 nm and II at 480 nm. The acid-base catalyzed xerogels synthesized with pH < 2.5 also exhibited two peaks, I at 400 nm and II at 475 nm. Peak II was not observed for the samples with pH 2.5. This phenomenon was attributed to the existence of pH dependent different forms of coumarin-4 molecule. The concentration-quenching phenomenon was observed for the acid catalyzed xerogels prepared with different dye concentration. TheFT-IR spectra indicated the existence of hydrogen bonds between the carbonyl groups of dye molecules and the silanol groups of gel matrix. The hydrogen bonding was the highest for the samples with the extremity pH, 0.6 and 7, resulting in the highest dye/gel matrix interactions, hence, the highest fluorescence peaks. The Raman studies indicated that the samples prepared with pH < 2.5 possessed relatively more number of 3-membered siloxane rings than 4-membered siloxane rings. The ring statistics was reversed for the samples with pH > 2.5. The number of silanol groups was higher for the samples with pH > 2.5. 相似文献
We report on the fabrication of pH‐disintegrable polyelectrolyte multilayer‐coated mesoporous silica nanoparticles (MSN) capable of triggered co‐release of cisplatin and model drug molecules. The outer polyelectrolyte multilayer was assembled from permanently cationic polyelectrolyte, poly(allyl amine hydrochloride) (PAH), and negatively charged polyelectrolyte, P(DMA‐co‐TPAMA), consisting of N,N‐dimethylacrylamide (DMA) and 3,4,5,6‐tetrahydrophthalic anhydride‐functionalized N‐(3‐aminopropyl)methacrylamide (TPAMA) monomer units, which exhibits pH‐induced charge conversion characteristics. Thus, the subtle alteration of solution pH from 7.4 to ≈5–6 can lead to the disintegration of outer polyelectrolyte multilayers, accompanied with the co‐release of cisplatin and RhB.
A novel modified base-catalyzed Sol-Gel process containing polyvinyl alcohol (PVA) has been proposed to prepare the porous SiO2 film. In this process, the growth of the sol particles was artificially broken off and controlled by acid-stabilising agent and PVA. As a result, a uniform and stable precursor solution was obtained in which the size of sol particles was stable. This new process efficiently overcomes the shortcomings of the traditional base-catalysed Sol-Gel process and can be employed to prepare porous SiO2 films with desired porosity and thickness. The influence of the catalyst, the reaction temperature, the pH value, the stabilizing agent and the PVA additive on the size of the SiO2 sol particles is systematically studied in part I. 相似文献
Angle-dependent dip coating (ADDC) is a modified dip coating technique that offers advantages for the production of optical
interference filters. In contrast to conventional dip coating (DC), the substrate is withdrawn from the coating solution under
an angle of inclination. Thereby, the two surfaces of the substrate are coated with individual film thicknesses. An experimental
setup for ADDC has been built and the decisive process influences on coating thicknesses have been evaluated. In order to
gain full control over the individual layer thicknesses, reaching from 20 nm to 160 nm, it is necessary to vary the following
process parameters: lifting speed, angle of inclination and concentration of the dipping solution. The results of coating
experiments prove the advantages of ADDC over DC. A first example aims at reducing the number of coating steps: an ADDC long
pass filter produced in 10 coating steps reaches the same optical performance as a conventional DC filter made in 16 steps.
A second example demonstrates the possibility to improve quality: a commercial DC beam splitter can be improved with respect
to the flatness of transmission and reflection curves when being produced in 4 steps by ADDC instead of 8 steps by DC. Furthermore,
ADDC offers the possibility to fabricate even narrow band pass filters, which are naturally difficult to obtain by conventional
DC. 相似文献