Mesoporous SBA-15 materials were functionalized with amine groups through postsynthesis and one-pot synthesis, and the resulting functionalized materials were investigated as matrixes for controlled drug delivery. The materials were characterized by FTIR, N2 adsorption/desorption analysis, ζ potential measurement, XRD, XPS, and TEM. Ibuprofen (IBU) and bovine serum albumin (BSA) were selected as model drugs and loaded onto the unmodified and functionalized SBA-15. It was revealed that the adsorption capacities and release behaviors of these model drugs were highly dependent on the different surface properties of SBA-15 materials. The release rate of IBU from SBA-15 functionalized by postsynthesis is found to be effectively controlled as compared to that from pure SBA-15 and SBA-15 functionalized by one-pot synthesis due to the ionic interaction between carboxyl groups in IBU and amine groups on the surface of SBA-15. However, SBA-15 functionalized by one-pot synthesis is found to be more favorable for the...

Functionalized SBA-15 materials as carriers for controlled drug delivery: influence of surface properties on matrix-drug interactions.

Formation of a new class of layered, microcrystalline polymers from a simple hydrolytic polycondensation of n-alkyltrichlorosilanes in water is demonstrated. The structure of the polymeric condensate, determined from a combination of spectroscopic, diffraction, and thermal analysis techniques, consists of highly uniform, pillared microcrystallites in which the inorganic siloxy backbones are present in periodic layers, each containing a monomolecular layer of intercalated water, separated by crystalline assemblies of alkyl chains. The alkyl-chain organization shows a remarkable resemblance to that in highly organized, self-assembled monolayers formed from the precursor silane molecules on hydrophilic substrates and this parallel lends support to the critical importance of water in monolayer self-assembly of silanes.

n-Alkylsiloxanes: From Single Monolayers to Layered Crystals. The Formation of Crystalline Polymers from the Hydrolysis of n-Octadecyltrichlorosilane

The modification of glass surfaces with (3-mercaptopropyl)trimethoxysilane and the application of this to DNA chip technology are described. A range of factors influencing the silanization method, and hence the number of surface-bound, chemically active thiol groups, were investigated using a design of experiment approach based on analysis of variance. The number of thiol groups introduced on glass substrates were measured directly using a specific radiolabel, [14C]cysteamine hydrochloride. For liquid-phase silanization, the number of surface-bound thiol groups was found to be dependent on both postsilanization thermal curing and silanization time and relatively independent of silane concentration, reaction temperature, and sample pretreatment. Depending on the conditions used in liquid-phase silanization, (1.3−9.0) × 1012 thiol groups/cm2 on the glass samples were bound. The reliability and repeatability of liquid- and vacuum-phase silanization were also investigated. Eighteen-base oligonucleotide probes...

A Factorial Analysis of Silanization Conditions for the Immobilization of Oligonucleotides on Glass Surfaces

The high-performance mechanical properties of certain spider silks can be radically altered by the addition of water. For example, unconstrained silk fibers from the major ampullate gland of the golden orb-weaving spider, Nephila clavipes, contract to about half of their original length when immersed in water. In this paper we use solid-state 13C and 2H NMR to study N. clavipes silk fibers, so as to address the molecular origins of supercontraction in the wet silk. Using 13C NMR, we study backbone dynamics and demonstrate that, when in contact with water, a substantial fraction of the glycine, glutamine, tyrosine, serine, and leucine residues in the protein backbone show dramatic increases in the rate of large-amplitude reorientation. 2H NMR of silk samples that incorporate leucine deuterated at one terminal methyl group provides a probe for dynamics at specific side chains along the fiber. Only a subset of these leucine residues is strongly affected by water. We suggest that the highly conserved YGGLGS(N...

Supercontraction and Backbone Dynamics in Spider Silk: 13C and 2H NMR Studies

Temperature-dependent 13C CP/MAS NMR investigations of C30 bonded interphases show two different signals for the (CH2)n chain, with a chemical shift difference of 2.6 ppm. They are characterized by selective population inversion (SPI) measurements and contact time variation experiments. One signal belongs to more rigid chains with trans conformations, the other one to more mobile chains with trans/gauche conformations. With decreasing temperature, more trans conformations are formed. HPLC separations of vitamin A acetate isomers have been performed from 50 °C to 2 °C. The on-line coupling of HPLC with 1H NMR spectroscopy yields information necessary for determination of the structures of the separated isomers. The conformational change of the C30 interphases with the temperature can also be seen in the retention order of the vitamin A acetate isomers. At low temperatures, the most angled 9-cis isomer is the most strongly retained compound, whereas at high temperatures, the linear all-trans isomer exhibits...

Temperature-Dependent Behavior of C30 Interphases. A Solid-State NMR and LC−NMR Study

Carbon-13 Nuclear Magnetic Resonance of Phenolic Resins. Positional Isomers of Bis(hydroxybenzyl)phenols and Bis(hydroxyphenyl)methanes

Formation of phenolic resins: mechanism and time dependence of the reaction of phenol and hexamethylenetetramine as studied by carbon-13 nuclear magnetic resonance and fourier transform infrared spectroscopy

Analysis of commercial sodium tripolyphosphates by phosphorus-31 Fourier transform nuclear magnetic resonance spectrometry

Extensive chlorination of aromatic substrates invariably leads to a gross mixture of positional isomers. Structural and compositional analysis of these isomeric mixtures can be quite challenging in view of the similar physical characteristics of some isomers, their heat sensitivity or nonvolatility. We have had extensive success in employing carbon-13 Fourier transform nuclear magnetic resonance (FT NMR) spectrometry to analyze such isomeric mixtures and wish to report our approach, especially the necessary precautions.

Quantitative Analysis of α,α,α,2,4-Pentachlorotoluene and α,α,α,2,5-Pentachlorotoluene Mixtures by Carbon-13 Fourier Transform Nuclear Magnetic Resonance Spectrometry

Stanley A. Sojka

Papers

Carbon-13 Nuclear Magnetic Resonance of Phenolic Resins. Positional Isomers of Bis(hydroxybenzyl)phenols and Bis(hydroxyphenyl)methanes

Formation of phenolic resins: mechanism and time dependence of the reaction of phenol and hexamethylenetetramine as studied by carbon-13 nuclear magnetic resonance and fourier transform infrared spectroscopy

Analysis of commercial sodium tripolyphosphates by phosphorus-31 Fourier transform nuclear magnetic resonance spectrometry

Quantitative Analysis of α,α,α,2,4-Pentachlorotoluene and α,α,α,2,5-Pentachlorotoluene Mixtures by Carbon-13 Fourier Transform Nuclear Magnetic Resonance Spectrometry