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PubMed1996

An indirect (derivatization) and a direct HPLC method for the determination of the enantiomers of ketorolac in plasma.

An indirect and a direct HPLC method for the quantification of the (R) and (S) enantiomers of ketorolac are described here. The indirect method employs the chiral amine (+)-R-1-(1-naphthyl)ethylamine to form disastereomeric amides; separation of the disastereomeric derivates is achieved by normal-phase HPLC with a mobile phase of ethyl acetate-hexane. The direct method uses a C18 solid-phase extraction column to extract ketorolac enantiomers from plasma; the reconstituted extract is then injected onto an alpha 1-acid glycoprotein chiral column using a mobile phase of isopropanol-phosphate buffer (0.05 M; pH 5.5). Both methods are reproducible, accurate, and stereospecific, and both have equivalent quantification limits (0.02 microgram ml-1 of plasma for each enantiomer), ranges (0.02-2.0 micrograms per aliquot of plasma), precision (% relative standard deviations of < or = 10.5% and < or = 10.8% for (R)- and (S)-ketorolac respectively), and accuracy (mean recoveries of 88.4-110% and 90.1-110% for (R)- and (S)-ketorolac respectively). Results of analyses of clinical samples by the two methods showed excellent agreement (slope near 1.0 and coefficients of correlation between 0.9740 and 0.9864 for both enantiomers).

Analgesics, Non-Narcotic↗
PubMed1996

Stereoselective determination of R(-)- and S(+)-prilocaine in human serum using a brush-type chiral stationary phase, solid-phase extraction and UV detection.

A chiral HPLC method was developed for the quantitation of R(-)- and S(+)-prilocaine in human serum. The method involves sensitive and selective detection of R(-)- and S(+)-prilocaine using normal-phase chiral HPLC on a pirkle-type naphthyl ethylamine stationary phase (Sumichiral OA-4700, 250 mm x 4 mm i.d.) at ambient temperature with a flow rate of 0.8 ml min-1. A sample clean-up procedure was used for isolation of the analytes of interest from human serum using Bond-Elut C18 columns with high recovery and selectivity. The detection limits were 4 ng ml-1 for R-prilocaine and 5 ng ml-1 for S-prilocaine. The limits of quantitation were 10 ng ml-1 for both enantiomers. Linear calibration curves in the 10-1000 ng ml-1 range showed good coefficients of determination > 0.999 (n = 3). Precision and accuracy of the method were within 4-5.8% and 1.5-4.8% respectively for R(-)-prilocaine, and 2.8-5.7% and 3.2-5.2% respectively for S(+)-prilocaine.

Anesthetics, Local↗
PubMed1997

Indirect enantiomeric separation of 2-arylpropionic acids and structurally related compounds by reversed phase HPLC.

A reversed-phase high-performance liquid chromatographic method, using an organic modifier-phosphate buffered mobile phase, for the determination of the enantiomeric composition of 2-arylpropionic acids and other structurally related compounds in microbial media is described. The method is based on the resolution of diastereoisomeric amides formed from the reaction of the arylpropionic acid with either (-)-(S)-alpha-methylbenzylamine or (-)-(S)-1-(naphthen-1-yl)ethylamine in the presence of 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide HCl and 1-hydroxybenzotriazole and incorporating an internal standard. The addition of sodium pentanesulphonate to the mobile phase as an ion-pairing agent was necessary to remove unreacted amine to avoid rapid column deterioration. The method provides and efficient, rapid and reproducible means of monitoring the microbial chiral inversion of 2-arylpropionic acids and other structurally related molecules.

Anti-Inflammatory Agents, Non-Steroidal↗
PubMed2001

Phencyclidine impairs latent learning in mice: interaction between glutamatergic systems and sigma(1) receptors.

The effect of phencyclidine (PCP) on latent learning was investigated using a one-trial water-finding task in mice. Mice without water deprivation were given PCP or saline before a training trial, which consisted of exposure to a novel open-field environment with an alcove containing a water tube. Twenty to twenty-four hours after water deprivation, animals were placed in the same apparatus and the time required to find the water tube measured (test trial). Saline-treated trained mice showed a significantly shorter time to find the water tube during the test trial (finding latency) than naive mice that had not been trained. When PCP (1mg/kg i.p.) was administered before the training trial, the finding latency was significantly prolonged in comparison with that in the saline-treated mice, indicating that PCP induced impairment of latent learning. 1-(3,4-Dimethoxy-phenethyl)-4-(3-phenylpropyl)piperazine dihydrochloride (SA4503: 0.3 mg/kg s.c.) and (+)-pentazocine (1 mg/kg s.c.), selective sigma(1) receptor agonists, or D-cycloserine (10 and 30mg/kg, s.c.), a glycine binding site agonist, significantly counteracted the PCP-induced impairment of latent learning, whereas (+)-SKF-10,047 (0.1-3 mg/kg s.c.), a putative sigma(1) receptor agonist, did not. The ameliorating effects of SA4503 and (+)-pentazocine were antagonized by N,N-dipropyl-2-(4-methoxy-3-(2-phenylethoxy) phenyl) ethylamine (NE-100: 1 mg/kg i.p.), a selective sigma(1) receptor antagonist. SA4503 also ameliorated the impairment of latent learning induced by dizocilpine, a non-competitive N-methyl-D-aspartate receptor antagonist, the effect being antagonized by NE-100. These results suggest that PCP induces an impairment of latent learning, this effect being mediated via glutamatergic systems, and that activation of sigma(1) receptors ameliorates impairment of latent learning induced by PCP.

Animals↗
PubMed1995

Lack of neuroprotective effect of sigma receptor ligands in the neurotoxicity of p-chloroamphetamine in rat brain.

We studied the mechanism of antagonism of p-chloroamphetamine-induced neurotoxicity by dextromethorphan. The pretreatment with potent and selective sigma receptor ligands, 4-phenyl-4-(1-phenylbutyl)piperidine (4-PPBP) and N,N-dipropyl-2-[4-methoxy-3-(2-phenylethoxy)phenyl]-ethylamine monohydrochloride (NE-100), did not alter the reduction of 5-hydroxytryptamine and 5-hydroxytryptamine and 5-hydroxyindoleacetic acid in the cerebral cortex by repeated administration of p-chloroamphetamine. These results suggest that sigma receptors might not play a significant role in the antagonism of p-chloroamphetamine-induced neurotoxicity by dextromethorphan.

Animals↗
PubMed1998

Molecular dynamics in solid L-adrenaline by proton NMR.

Proton NMR measurements of the spectrum, second moment, spin-lattice relaxation time T1 and dipolar relaxation time T1D were carried out on polycrystalline L-adrenaline at 14 and 25 MHz between 55 and 400 K. Between 70 K and 250 K relaxation is dominated by C3 reorientation of the single methyl group in each molecule, characterized by an activation energy 8.3+/-0.3 kJ/mole. Below 70 K tunnelling assisted relaxation is significant, characterized by an excitation energy of 1.9+/-0.2 kJ/mole. Above 250 K an additional molecular motion becomes significant, with activation energy above 28 kJ/mole, attributed to conformational motion of the methylene group in the ethylamine side chain.

Epinephrine↗
PubMed2003

Oxidase enzyme immobilisation through electropolymerised films to assemble biosensors for batch and flow injection analysis.

Glucose oxidase, lactate oxidase, L-aminoacid oxidase and alcohol oxidase were immobilised on new films based on 2,6-dihydroxynaphthalene (2,6-DHN) copolymerised with 2-(4-aminophenyl)-ethylamine (AP-EA) onto the Pt electrodes. The electropolymerisation was performed by cyclic voltammetry. Different scan rates and scan potential ranges were investigated and selected according to the monomers used. These sensors were tested for hydrogen peroxide, ascorbic acid and acetaminophen by cyclic voltammetry and amperometry. The amperometric studies were carried out in batch as well as in a flow injection analysis (FIA) system. Analytical parameters such as reproducibility, interference rejection, response time, buffer, storage and operational time of the sensors have been studied. These films were also characterised by X-ray photoelectron spectroscopy (XPS). Different strategies for enzyme immobilisation were performed and discussed: enzyme entrapment in the film during the electropolymerisation and covalent attachment of the enzyme to the film via a carbodiimide (1-ethtl-3-(3-dimethylaminopropyl)carbodiimide, EDC) or glutaraldehyde. Different parameters were considered in order to optimise the immobilisation procedures. Results provide a guide to design high sensitive, stable and interference-free biosensors. In addition, studies were performed using these probes in an original FIA based on solenoidal valves. Sensor stability, life time and dynamic range were also optimised in these conditions.

Biosensing Techniques↗
PubMed2000

5-Alkyltryptamine derivatives as highly selective and potent 5-HT1D receptor agonists.

A series of 5-alkyltryptamines (6) and the corresponding conformationally constrained analogues (8) have been synthesized. The structure activity relationships (SAR) at the 5-position of the indole skeleton and the ethylamine side chain have been studied. Functional activities were assessed using isolated rabbit saphenous vein. Potent, selective ligands were found (6e, Ki 2.5 nM, 5-HT1B/5-HT1D 125-fold) that have potential for treating acute migraine.

Animals↗
PubMed2001

Synthesis and characterization of fluorinated and iodinated pyrrolopyrimidines as PET/SPECT ligands for the CRF1 receptor.

Fluorine-18 labeled fluorobutyl[2,5-dimethyl-7-(2,4,6-trimethylphenyl)-7H-pyrrolo [2,3-d] pyrimidin-4-yl]ethylamine (FBPPA) and iodine-123 labeled butyl[2,5-dimethyl-7-(4-iodo-2,6-dimethylphenyl)-7H-pyrrolo[2,3-d]pyrimidin-4-yl]ethyl-amine (IBPPA) were synthesized in the development of a CRF receptor ligand. The methods of synthesis, in vitro binding assays, radiolabeling and in vivo tissue distribution in rats are described. Fluorine-18 labeled FBPPA was prepared with high specific activity (3 x 10(4) Ci/mmol) by nucleophilic displacement with an average radiochemical yield of 6% (EOB). Iodine-123 labeled IBPPA was prepared by electrophilic iododestannylation with good yield (60%) and high specific activity (3.3 x 10(3) Ci/mmol). The retention of FBPPA and IBPPA in the pituitary was good (1.16% i.d./g and 2.35% i.d./g respectively at 60 min). However, the accumulation of radioactivity in the brain for both radiotracers was very low at all time points of the study, which demonstrated the difficulties for these radiopharmaceuticals to penetrate the blood brain barrier (BBB).

Animals↗
PubMed1997

Synthesis and tissue distribution of substituted [125I]iodophenylamine derivatives: possible brain imaging agents.

The synthesis and brain uptake in mice of the radioiodinated derivatives of N,N-dimethyl-N'-(iododimethoxyphenyl)-1,3-propanediamine, as well as the N-substituted derivatives of (iodoalkylphenyl)isopropyl, iodoalkylphenylethylamine and 3,4-(methylenedioxy)phenyl-amphetamine (MDA) are described. These compounds contain structural features of both IMP and HIPDM, the cerebral perfusion agents currently in clinical use. The radiolabeled analogs were obtained via the [125I]I exchange method, or by [125I]NaI treatment of the iodo-free precursor in the presence of an oxidant. Following intravenous injection in mice, all compounds showed important radioactivity concentrations in the lungs and kidneys. The N-substituted (iodoalkylphenyl)isopropyl and iodoalkylphenyl-ethylamine derivatives displayed a high initial brain uptake (> 10% IDg-1) followed by a rapid clearance phase, resulting in lower brain-to-blood ratios as those reported for IMP and HIPDM. In contrast, N,N-dimethyl-N'-(iododimethyphenyl)-1,3-propanediamine derivatives featuring the iodo substituent on the benzene carbon adjacent to the methyl amine group and the methoxy substituents on the 2,5- or 2,4-positions, showed low but more persistant brain uptake. Combined with fast blood clearance, this resulted in high brain-to-blood ratios at later time points. Among all compounds tested, the highest brain-to-blood ratio was observed with compound N,N-dimethyl-N'-(6-iodo-3,4-dimethyoxyphenyl)-1,3-propanediamine (27e), reaching a maximum of > 20 at 12 h post-injection.

Aniline Compounds↗
PubMed1998

Synthesis and preliminary evaluation of [11C]NE-100 labeled in two different positions as a PET sigma receptor ligand.

N,N-Dipropyl-2-[4-methoxy-3-(2-phenylethoxy)phenyl]ethylamine (NE-100) was labeled with 11C in two different positions by the alkylation of an N-despropyl precursor with [11C]propyl iodide and of an O-desmethyl precursor with [11C]methyl iodide and was evaluated for the potential as a tracer for mapping sigma 1 receptors in the CNS and peripheral organs by PET. Following i.v. injection of [N-propyl-11C]NE-100 or [O-methyl-11C]NE-100 into mice, the two tracers showed similar tissue distribution patterns except for the liver and brain. With the coinjected carrier NE-100 or haloperidol, the uptake of [N-propyl-11C]NE-100 by the liver, pancreas and spleen was significantly decreased at 15 min after injection, whereas the effect was not significant for [O-methyl-11C]NE-100. The coinjection of NE-100 enhanced the brain uptake of the two tracers. Haloperidol also enhanced the brain uptake of [N-propyl-11C]NE-100, but not that of [O-methyl-11C]NE-100. The regional brain distribution assessed with [O-methyl-3H]NE-100 was consistent with the distribution pattern of the sigma receptors. Four sigma drugs reduced the regional brain uptake of [O-methyl-3H]NE-100 to 70%-90% of the control. In an ex vivo autoradiographic study of the rat brain, the uptake of [O-methyl-11C]NE-100 was blocked by carrier NE-100 or haloperidol (53%-59% of the control in the cortex), which suggests a receptor-specific distribution. These results show that [O-methyl-11C]NE-100 has limited potential as a PET ligand for mapping sigma 1 receptors in the peripheral organs and the CNS because of high nonspecific binding.

Animals↗
PubMed1999

In vivo binding of [11C]nemonapride to sigma receptors in the cortex and cerebellum.

Radiolabeled nemonapride (NEM, YM-09151-2) is widely used as a representative dopamine D2-like receptor ligand in pharmacological and neurological studies, and 11C-labeled analog ([11C]NEM) has been developed for positron emission tomography (PET) studies. The aim of this study was to evaluate whether [11C]NEM binds in vivo to sigma receptors. [11C]NEM and one of six dopamine D2-like receptor ligands or seven sigma receptor ligands were co-injected into mice, and the regional brain uptake of [11C]NEM was measured by a tissue dissection method. The striatal uptake of [11C]NEM was reduced by D2-like receptor ligands, NEM, haloperidol, (+)-butaclamol, raclopride, and sulpiride, but not by a D4 receptor ligand clozapine. In the cortex and cerebellum the uptake was also reduced by D2-like receptor ligands with affinity for sigma receptors, but not by raclopride. Although none of seven sigma receptor ligands, SA6298, N,N-dipropyl-2-[4-methoxy-3-(2-phenylethoxy)phenyl]ethylamine hydrochloride (NE-100), (+)-pentazocine, R(-)-N-(3-phenyl-1-propyl)-1-phenyl-2-aminopropane hydrochloride ([-]-PPAP), (-)-pentazocine, R(+)-3-(3-hydroxyphenyl)-N-propylpiperidine hydrochloride ([+]-3-PPP), and (+)-N-allylnormetazocine hydrochloride ([+]-SKF 10047), blocked the striatal uptake, five of them with relatively higher affinity significantly reduced the [11C]NEM uptake by the cortex, and four of them reduced that by the cerebellum. We concluded that [11C]NEM binds in vivo not only to dopamine D2-like receptors in the striatum but also to sigma receptors in other regions such as cortex and cerebellum.

Animals↗
PubMed2001

Hydrogen-deuterium exchange at non-labile sites: a new reaction facet with broad implications for structural and dynamic determinations.

Hydrogen-deuterium exchange at non-labile sites is reported. The conjugate bases of isophthalic acid (m-C6H4(CO2H)2), 2-oxoglutaric acid (HO2CCOCH2CH2CO2H), and 2-methylisophthalic acid (2-CH3-1,3-C6H4(CO2H)2) undergo scrambling with 1, 2, and 3 carbon-centered hydrogens under a variety of conditions. Likewise, protonated 2-(m-methoxyphenyl)-ethylamine ((m-CH3OC6H4)CH2CH2NH2) undergoes up to 5 H/D exchanges upon gentle activation whereas the conjugate acid of 2-phenylethylamine (C6H5CH2CH2NH2) requires the presence of ammonia-d3 in order to be pushed to undergo up to 8 H/D exchanges. The very act of electrospraying ions can result in extensive movement of deuterium to carbon centers and, in some cases, could not be prevented. These findings offer great promise for future exploitation but also suggest that the interpretation of many H/D exchange experiments using mass spectrometry as the analytical tool could be in error.

Carboxylic Acids↗
PubMed1993

Miniaturized flexible amperometric lactate probe.

A flexible lactate electrode was made of 400 +/- 100 7-micron-diameter carbon fibers, epoxy embedded in a 0.3-mm-diameter polyimide tubing. The electrode was modified by precipitating on it the relatively insoluble complex formed between 1100 kDa partially N-ethylamine quaternized poly[(vinylpyridine)-Os(bipyridine)2Cl]Cl (POs-EA) and lactate oxidase. The steady-state lactate electrooxidation current, at 2 mM lactate concentration and at 22 degrees C, was 400 nA. The 50 +/- 10 microAc cm-2 current density and the 20 mA cm-2 M-1 sensitivity decreased only by 5% when the partial pressure of oxygen was increased from 0.0 to 0.2 atm. The electrode retains its sensitivity after dry storage at 4 degrees C for 4 months in air but loses half of its sensitivity in 7 h at 37 degrees C through polymer desorption when operated at 0.4 V (SCE). To eliminate interference by species that are electrooxidized at 0.4 V (SCE), the lactate-sensing probe was (a) electrically insulated with an epoxy made of poly(vinylimidazole) cross-linked with ethylene glycol diglycidyl ether and (b) coated with an immobilized horseradish peroxidase (HRP)/glucose oxidase (GOX) film. The latter film was formed by coimmobilizing the two enzymes through periodate oxidation of their oligosaccharides to aldehydes and forming Schiff bases between the polyaldehydes and the enzymes' lysyl amines. In the presence of 1 mM glucose and in air, the interfering electrooxidation of 0.1 mM ascorbate was reduced by a factor of 20. This reduction results from formation of hydrogen peroxide in the glucose-catalyzed reaction and H2O2 oxidation of the ascorbate in a reaction catalyzed by HRP.

Biosensing Techniques↗
PubMed2003

Optical sensor for amine vapors based on dimer-monomer equilibrium of indium(III) octaethylporphyrin in a polymeric film.

A novel transduction chemistry for the development of a polymer film-based optical sensor that responds reversibly to gas-phase amine species at sub-ppm levels is described. The sensor is based on the equilibrium of a indium(III) octaethylporphyrin hydroxide ion-bridged dimer species with corresponding monomeric porphyrins within a thin poly(vinyl chloride) film as a function of the level of volatile amine in the surrounding gas phase. The presence of amines causes the dimeric species to be converted to monomer via the ligation of the amine with the In(III) center of the porphyrin structure. This yields a significant change in the visible absorption spectrum of the film, with a decrease in the intensity of the Soret band corresponding to the dimer (lambdamax = 390 nm) and a concomitant increase in the Soret band for the monomer lambdamax = 406-408 nm). Response to different amines is based on their relative partition coefficient into the polymer film and their strength of axial ligation reactions, with a selectivity pattern of 1-butylamine > 1-propylamine > pyridine > triethylamine > ethylamine > methylamine > diethylamine > tert-butylamine > ammonia. It is further shown that a significant concentration of dimeric species within the polymer film can only be achieved if appropriate amounts of lipophilic anionic sites are also incorporated into the polymer in the form of a tetraphenylborate derivative and the resulting film is equilibrated briefly with water prior to gas-phase measurements. With optimized film compositions, 1-butylamine can be detected in the gas phase to levels approaching 0.1 ppm, while less lipophilic ammonia can be monitored down to 10 ppm, with fully reversible responses to each species. A simple mathematical model for the response of the amine sensor is presented and shown to predict the optical behavior observed.

Amines↗
PubMed2005

Sol-gel modified poly(dimethylsiloxane) microfluidic devices with high electroosmotic mobilities and hydrophilic channel wall characteristics.

Using a sol-gel method, we have fabricated poly(dimethylsiloxane) (PDMS) microchips with SiO2 particles homogeneously distributed within the PDMS polymer matrix. These particles are approximately 10 nm in diameter. To fabricate such devices, PDMS (Sylgard 184) was cast against SU-8 molds. After curing, the chips were carefully removed from the mold and sealed against flat, cured pieces of PDMS to form enclosed channel manifolds. These chips were then solvated in tetraethyl orthosilicate (TEOS), causing them to expand. Subsequently, the chips were placed in an aqueous solution containing 2.8% ethylamine and heated to form nanometer-sized SiO2 particles within the cross-linked PDMS polymer. The water contact angle for the PDMS-SiO2 chips was approximately 90.2 degrees compared to a water contact angle for Sylgard 184 of approximately 108.5 degrees . More importantly, the SiO2 modified PDMS chips showed no rhodamine B absorption after 4 h, indicating a substantially more hydrophilic and nonabsorptive surface than native PDMS. Initial electroosmotic mobilities (EOM) of (8.3+/-0.2)x10(-4) cm2/(V.s) (RSD=2.6% (RSD is relative standard deviation); n=10) were measured. This value was approximately twice that of native Sylgard 184 PDMS chips (4.21+/-0.09)x10(-4) cm2/(V.s) (RSD=2.2%; n=10) and 55% greater than glass chips (5.3+/-0.4)x10(-4) cm2/(V.s) (RSD=7.7%; n=5). After 60 days of dry storage, the EOM was (7.6+/-0.3)x10(-4) cm2/(V.s) (RSD=3.9%; n=3), a decrease of only 8% below that of the initially measured value. Separations performed on these devices generated 80,000-100,000 theoretical plates in 6-14 s for both tetramethylrhodamine succidimidyl ester and fluorescein-5-isothiocyanate derivatized amino acids. The separation distance was 3.5 cm. Plots of peak variance vs analyte migration times gave diffusion coefficients which indicate that the separation efficiencies are within 15% of the diffusion limit.

Journal Article↗
PubMedDate not supplied

Molecular amplifiers: synthesis and functionalization of a poly(aminopropyl)dextran bearing a uniquely reactive terminus for univalent attachment to biomolecules.

The synthesis and characterization of the versatile dextran-based molecular amplifier 6 is described. Dextran (Mr = 40,200) was selectively monofunctionalized in high yield at its reducing terminus via reductive amination with 2-(4-nitrophenyl)ethylamine to give 1. The nitro group in 1 serves as a masked amino group which is eventually converted into a reactive isothiocyanato group used for monovalent attachment of the completed assembly to a target molecule. Cyanoethylation of 1 gave the terminally nitrophenylated poly(cyanoethyl)dextran 5 which was selectively reduced to the corresponding poly(aminopropyl) derivative 6 with BH3.THF, a reagent which preserved the end nitro group. Conjugation of amplifier 6 with the isothiocyanate-derivatized Gd(III) chelate 7 gave conjugate 9 containing about 22 mol of chelate/mol of amplifier. The T1 relaxivity per Gd(III) ion of 9 in H2O was 15.0 mM-1 s-1, about 3-fold higher than that of free Gd(III)DTPA in H2O. The nitro group of 9 was then selectively reduced to the corresponding amine 10, which was converted into isothiocyanate 11. The reactivity of the single isothiocyanate group in 11 was demonstrated by coupling to 5-aminoeosin, giving conjugate 12. Amplifier 6 was also conjugated with the acid-labile N-cis-aconityl derivative 8 of the potent anticancer agent daunomycin. The nitro group of the resulting conjugate 13 was then reduced and the resulting amine 14 was converted into mono isothiocyanate 15. Compound 15 reacted with a water-insoluble amine-containing solid support to give 16. Free daunomycin was released from 16 by exposure to citrate-phosphate buffer at pH 4.0.

Chromatography, Gel↗
PubMedDate not supplied

Antigen-decorated shell cross-linked nanoparticles: synthesis, characterization, and antibody interactions.

Antigen-decorated shell cross-linked knedel-like nanoparticles (SCKs) were synthesized and studied as multivalent nanoscale surfaces from which antibody-binding units were presented in a manner that was designed to approach virus particle surfaces. The SCK nanostructures were fabricated with control over the number of antigenic groups, from mixed micellization of amphiphilic diblock copolymer building blocks that contained either an antigen (2,4-dinitrophenyl) or an ethylpropionate group at the hydrophilic alpha-chain terminus. Amphiphilic diblock copolymers were synthesized by atom transfer radical polymerization of tert-butyl acrylate and methyl acrylate sequentially from either a 2,4-dinitrophenyl-functionalized initiator or ethyl 2-bromopropionate, followed by selective removal of the tert-butyl groups to afford 2,4-dinitrophenyl-poly(acrylic acid)60-b-poly(methyl acrylate)60 (DNP-PAA(60)-b-PMA60) and poly(acrylic acid)70-b-poly(methyl acrylate) (PAA70-b-PMA70). Micelles were assembled via addition of water to THF solutions of the polymers in 0:1, 1:1, and 1:0 molar ratios of DNP-PAA60-b-PMA60 to PAA70-b-PMA70, followed by dialysis against water. The acrylic acid groups of the micelle coronas were partially cross-linked (nominally 50%) with 2,2'-(ethylenedioxy)bis(ethylamine), in the presence of 1-(3'-dimethylaminopropyl)-3-ethylcarbodiimide methiodide. Following extensive dialysis against water, the 0%, 50%, and 100% dinitrophenylated shell cross-linked nanoparticles (DNP-SCKs) were characterized with dynamic light scattering (DLS), transmission electron microscopy (TEM), atomic force microscopy (AFM), differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), infrared and UV-vis spectroscopies, and analytical ultracentrifugation (AU). The surface accessibility and bioavailability of the DNP units upon the DNP-SCKs were investigated by performing quenching titrations of fluorescein-labeled IgE antibody in solution and degranulation of IgE sensitized RBL-2H3 cells. The DNP antigens proved to be surface-available and able to form multivalent bonds with IgE antibodies, causing degranulation.

Animals↗