3-sulfopropyl Methacrylate Research Articles

Preconcentration and frontal electroelution of amino acids for in-line solid-phase extraction–capillary electrophoresis

A new frontal electroelution approach that can be used for the preconcentration of amino acids in in-line solid-phase extraction–capillary electrophoresis (SPE–CE) has been developed. A single capillary was employed featuring a short monolithic SPE column created inside the capillary via photo-initiated, free-radical polymerisation of 3-sulfopropyl methacrylate and butyl methacrylate monomers. A weak electrolyte of dilute H 2SO 4, pH 2.9, was found to promote adsorption of the amino acids onto the SPE column. Elution of the amino acids was achieved using a dual solvation/ion-exchange transient boundary mobilised via EOF by using a strong electrolyte containing 62.5 mM ethylenediamine, pH 2.9 with H 2SO 4 and 40% (v/v) acetonitrile. Using these two electrolytes, tryptophan was adsorbed onto the SPE column in weak electrolyte and eluted via a frontal electroelution mechanism in the strong electrolyte. Injections up to 20 min, corresponding to over 14 column volumes (or 1400% of the capillary volume) of sample provided quantitative extraction of tryptophan from the weak electrolyte and were eluted without any loss in efficiency. This represents a practical increase of approximately 300-fold when compared to a typical hydrodynamic injection occupying 5% of the capillary volume.

Separation of antidepressants by capillary electrophoresis with in-line solid-phase extraction using a novel monolithic adsorbent

The separation of three selective serotonin reuptake inhibitors (SSRIs) by capillary electrophoresis (CE) with fully integrated solid-phase extraction (SPE) is described. Polymeric monolithic SPE modules were prepared in situ within a fused silica capillary from either butyl methacrylate- co-ethylene dimethacrylate or 3-sulfopropyl methacrylate- co-butyl methacrylate- co-ethylene dimethacrylate. Using a 1 cm SPE module placed at the inlet of the capillary, a mixture of sertraline, fluoxetine and fluvoxamine was extracted from aqueous solution by applying a simple pressure rinse. Under pressure-driven conditions, efficient elution was possible from both SPE materials investigated using 50 mM phosphate buffer, pH 3.5 in acetonitrile (20/80, v/v). Two different strategies were investigated for the efficient elution and subsequent CE separation. Injection of an aqueous sample plug directly into the non-aqueous elution/separation buffer was found to be unsuitable with poor elution profiles observed in the electrodriven mode. Alternatively, a sample plug equivalent to several capillary volumes could be injected by pressure followed by filling the capillary with the non-aqueous elution/separation buffer from the outlet end using a combination of pressure and electrodriven flow. Using a neutral monolith, efficient elution/separation was not possible due to an unstable electroosmotic flow (EOF), however, by adding the ionisable monomer, 3-sulfopropyl methacrylate to the SPE module to increase and stabilise the EOF, it was possible to achieve efficient elution from the SPE module, followed by baseline separation by CE using a 200 mM acetate buffer, pH 3.5 in acetonitrile (10/90, v/v). With enrichment factors of over 500 achieved for each of the analytes this demonstrates the potential of in-line SPE-CE for the sensitive analysis of these drugs.

Characterization and photooxidative behaviour of nanocomposites formed with polystyrene and LDHs organo-modified by monomer surfactant

Layered double hydroxide (LDH) organo-modified by a surface-active monomer, 3-sulfopropyl methacrylate (SPMA) was used as filler for polystyrene (PS). Different nanocomposites SPMA/LDH:PS were prepared by bulk polymerization process using low amount of initiator. The two components, filler and polymer, as well as the degree dispersion of the reactive filler as a function of its loading in PS were characterized by a combination of several techniques: X-ray diffraction, high resolution 13C CP-MAS NMR, FTIR, UV–visible, thermal analysis, SEC and MET. The nanocomposites were submitted to UV-light exposures in the presence of oxygen. The oxidation photoproducts and the rates of oxidation were compared for the various samples. It was shown that the filler was not modifying the oxidation mechanism of the polymer, but had a slight effect on the oxidation rate.

Polymerization of Sulfopropyl Methacrylate, a Surface Active Monomer, within Layered Double Hydroxide

Hybrid organic−inorganic phases composed of a surface active monomer, sulfopropyl methacrylate (SPMA), incorporated within the lamellar structure of layered double hydroxides (LDH) of cation composition ZnnAl, n = 2, 3 are obtained by the coprecipitation method. Monomer intercalation and its subsequent polymerization are characterized by means of FTIR and 13C CP-MAS NMR spectroscopies. Complementary information was gathered from a thermal study of the potassium salt of SPMA. In-situ X-ray diffraction over a range of temperature performed on the hybrid phase Zn2Al/SPMA shows clearly that the polymerization process is found first to slightly contract and then to disagglomerate the lamellar structure, while the integrity of the layers is maintained, giving rise to well-dispersed particles.

Artificial receptor-attached amphiphilic copolymer for barbiturate binding in aqueous media.

A water-soluble self-associating amphiphilic copolymer was employed to provide a microenvironment for the solvation of a hydrogen-bonding barbiturate artificial receptor, to facilitate molecular recognition in water. The receptor-attached amphiphilic polymer (RP) was synthesized through random copolymerization of 3% (mol) barbiturate receptor-monomer, 70% (mol) 3-sulfopropyl methacrylate, and 27% (mol) n-dodecyl acrylate. Difference UV spectra of pH 6.5 aqueous solutions of phenobarbital and receptor-polymer (RP) gave peaks and valleys at 272 and 301 nm respectively, consistent with binding characteristics of monomeric barbiturate receptors in chloroform. Specific association between phenobarbital and the receptor-polymer was further indicated based on investigations of a receptor-free control polymer (CP) of similar polar/nonpolar monomer ratio. Micellar electrokinetic chromatography was applied for studying polymer-phenobarbital association, by capillary electrophoresis.

Atom Transfer Radical Polymerization of Potassium 3-Sulfopropyl Methacrylate: Direct Synthesis of Amphiphilic Block Copolymers with Methyl Methacrylate

The synthesis of potassium 3-sulfopropyl methacrylate (SPMA) homopolymers and amphiphilic block copolymers with methyl methacrylate (MMA) by ATRP in water/DMF mixed solvent at 20 °C using a Cu/bipyridine catalyst and halogen exchange is described. SPMA homopolymerization in pure water was poorly controlled even when 200% of Cu(II)Cl2 with respect to Cu(I)Cl was added, leading to a relatively high polydispersity (1.38). In water:DMF 50:50 (v/v), addition of at least 60% of Cu(II)Cl2 with respect to Cu(I)Cl allowed to obtain a good control of the polymerization. Linear kinetic plots up to very high conversion were observed and the final polydispersities were relatively low (1.15−1.25). Good self-blocking efficiencies were demonstrated by chain extension experiments even when the first block conversion before the addition of the second feed was very high (>90%). Amphiphilic block copolymers with MMA (number-average degree of polymerization Xn,SPMA = 50, Xn,MMA = 25) were directly prepared in water:DMF 40:60 (v/v) without using protecting group chemistry or post-polymerization derivatization. The first-order kinetic plot for MMA polymerization was linear up to 96% conversion. Two block copolymers with the same composition, p(SPMA50-b-MMA25)1pot and p(SPMA50-b-MMA25)2pot, were prepared with “one-pot” and “two-pot” procedures. p(SPMA50-b-MMA25)2pot prepared using a purified pSPMA macroinitiator for MMA polymerization gave well-defined core−shell spherical micelles with an average hydrodynamic radius of about 14 nm determined by dynamic light scattering (DLS) measurements. p(SPMA50-b-MMA25)1pot prepared using the sequential monomer addition gave large micellar clusters (more than 100 nm) in addition to simple but smaller micelles. A tentative explanation to the presence of the larger aggregates was given.

Low protein fouling synthetic membranes by UV-assisted surface grafting modification: varying monomer type

The sensitivity of photo-induced grafting and polymerization and the filtration performance of six different grafted monomers [2 neutral ( N-2-vinyl pyrolidinone (NVP), 2-hydroxyethyl methacrylate (HEMA)), 2 weak (carboxylic) acids (acrylic acid (AA), 2-acrylamidoglycolic acid (AAG)), and 2 strong (sulfonic) acids (3-sulfopropyl methacrylate (SPMA), 2-acrylamido-2-methyl-1-propanesulfonic acid (AMPS))] on poly(ether sulfone) (PES) membranes were measured. The approach was to (i) follow the degree of grafting on commercial PES ultrafiltration membranes with varying pore size (10–300 kDa) as a function of monomer concentration multiplied by irradiation time (the initial linear slopes are termed “sensitivity”), (ii) compare the wettabilities of various grafted membranes (PES-gr-monomer) as a measure of the hydrophilicity of the grafted surfaces, and (iii) contrast their the filtration performances (protein retention, hydrodynamic resistance, and cleanability) with 1 g/l protein (bovine serum albumin, BSA) in phosphate buffer solution (PBS). Although all the grafted and polymerized monomers increased the surface wettability of the PES-grafted membranes over that for the unmodified PES membranes, their effect on filtration performance was different. Using the 50 kDa PES membranes for grafting, membranes with superior performance (high protein retention, high protein solution flux, and low irreversible fouling) were obtained with the NVP, AMPS and AA monomers. Neither commercial regenerated cellulose or PES membranes were as competitive. For larger pore-size membranes (70 and 100 kDa), however, PES-gr-AMPS and PES-gr-AA membranes exhibited reasonably high BSA rejection and protein solution fluxes with excellent cleaning capability (with projected high long-term performance) as compared with the control membranes. Grafting of NVP and HEMA resulted in an initial substantial decrease in BSA rejection due to their tendency to dissolve PES, but with further grafting rejection was recovered. These two monomers also exhibited reduced grafting sensitivity and reduced total hydraulic resistance with increases in wettability (or degree of grafting, DG) as compared with the as-received commercial PES membrane. Grafting sensitivity was inversely proportional to monomer size [(molar volume) 1/3] for the charged monomers. Also, universal plots of DG versus a composite parameter of monomer concentration multiplied by time of irradiation were obtained and can be used for prediction. We also provide a detailed experimental protocol of how to choose vinyl monomers for preparing high performance ultrafiltration membranes using graft-assisted photo-polymerization and a new figure-of-merit to help compare modifications.

Low fouling synthetic membranes by UV-assisted graft polymerization: monomer selection to mitigate fouling by natural organic matter

A UV-assisted photochemical graft polymerization technique was used to produce modified poly(ether sulfone) (PES) ultrafiltration (UF) membranes that exhibit reduced interaction with natural organic matter (NOM), as a route to reduce the fouling caused by NOM. We evaluated six different hydrophilic monomers for their ability to reduce fouling by NOM: two are neutral monomers, N-vinyl-2-pyrrolidinone (NVP) and 2-hydroxyethyl methacrylate (HEMA); two are weakly acidic (carboxylic) monomers, acrylic acid (AA) and 2-acrylamidoglycolic acid (AAG); and two are strongly acidic (sulfonic) monomers, 3-sulfopropyl methacrylate (SPMA) and 2-acrylamido-2-methyl-1-propanesulfonic acid (AMPS). Grafting increased membrane surface wettability and shifted the membrane pore size distribution to smaller sizes, which increased natural organic matter rejection (except in the case of NVP). Total fouling appeared to depend primarily on solute rejection, and varied in a complex way that could be interpreted in the context of the NOM molecular weight distribution. Reversible fouling resulting from cake formation was only weakly dependent on membrane surface chemistry; in contrast, irreversible fouling exhibited a marked dependence on surface chemistry. Membranes modified with the weak acid AA monomer were able to reduce irreversible fouling to zero, in contrast to other strongly hydrophilic monomers such as HEMA and AAG, which increased irreversible fouling relative to the unmodified membrane. We conclude that wettability (or hydrophilicity) is not an appropriate parameter for estimating reduced fouling potential for NOM feeds, as it is for feeds containing protein. We hypothesize that this is a consequence of the structural and chemical heterogeneity of NOM. The AA-modified membranes exhibited excellent filtration performance over multiple runs, and outperformed a regenerated cellulose (RC) membrane having similar initial NOM rejection.

Previous trauma, personality dimensions and psychological symptoms after a stressful event

S-layer recrystallization is part of, at least, two major scientific and technological challenges: a model system to study 2-D polymer crystal formation and a bottom-up approach to build biomimetic and functional interfaces. In particular, the self-assembly process of the bacterial surface layer protein (SbpA) might be influenced by two different interactions: protein/substrate and protein/protein. In this work, we are taking advantage of the versatility of already well known polymer brushes to study the self-assembly mechanism of the S-protein SbpA. In particular, the recrystallization pathway of the protein has been modified by the underlying polymer charge and accessible volume offered by the positively charged poly{[2-(methacryloyloxy)ethyl] trimethylammonium chloride} (PMETAC), the negative poly(sulfo propyl methacrylate) (PSPM) and the non-charged poly(N -isopropyl acrylamide) (PNIPAAm). The recrystallization pathways on polymer brushes have been compared with the bacterial biomimetic case represented by the secondary cell wall polymer (SCWP). Results concerning protein adsorption kinetics, viscoelastic properties, crystal lattice parameters and domain formation are presented, and have been obtained with Quartz Crystal Microbalance with Dissipation Monitoring (QCMD) and Atomic Force Microscopy (AFM).

Synthesis and characterization of polyelectrolyte hydrogels with controlled swelling behaviour

AbstractCopolymerization of sulfopropyl methacrylate potassium salt (K‐SPMA) and 2‐acrylamido‐2‐methyl propane sulfonic acid (AMPS) has been studied in the range 10–90% K‐SPMA in the feedstock. The reactivity ratios have been determined for K‐SPMA/AMPS copolymers. The copolymer compositions, utilized for determining the reactivity ratio, have been determined from nitrogen content. Crosslinked poly(AMPS) and K‐SPMA/AMPS copolymers were prepared in water in the presence of potassium persulfate as initiator and N,N‐methylene bisacrylamide (MBA) as tetrafunctional crosslinker. Irradiation of K‐SPMA and AMPS with an electron‐beam was carried out at 50 wt% aqueous solution with low pH and irradiation dose 40–120 kGy. The swelling behaviour of highly crosslinked K‐SPMA/AMPS copolymer polyelectrolyte gels in aqueous medium was studied in the presence of different types of salts. The crosslink density, the average molecular weight between the crosslinks and the dissociation constant (pKa) of the crosslinked polymer were determined from stress–strain measurements.© 2001 Society of Chemical Industry

Pulse and gamma radiolysis studies of 3-sulfo propyl methacrylate in aqueous solutions

Radiation induced polymerization of 3-sulfo propyl methacrylate (SPMA) in aqueous solution (10wt%) has been studied by steady state and pulse radiolysis techniques. The effect of radiation characteristics such as irradiation dose, dose rate and the presence of crosslinking agent on the gel formation of SPMA monomer has been investigated. In N2 -saturated solution, the gel formation doses for SPMA were found to be 70 and 258Gy at dose rates of 1.2 and 5kGyh−1, respectively. The swelling ratio results showed that the gel obtained at a constant dose of 0.8kGy dose swells ∼630 times of its dry weight at a dose rate of 5kGyh−1 whereas it is 394 times of its dry weight for the dose rate 1.2kGyh−1. The reactions of the primary radicals of water radiolysis such as eaq−, H-atom, OH radical, O−, and some oxidizing radicals like N3,Cl2−,SO4− and reducing species like CO2− with SPMA have been studied using pulse radiolysis technique. The results show that the reaction of eaq−, H-atom and OH radicals with SPMA are in the diffusion controlled limit with their respective bimolecular rate constant values being 8.6×109, 2×109 and 1.5×1010dm3mol−1s−1. The radical anion, SPMA− , (λmax=280nm) is observed to undergo fast protonation forming H-adduct, SPMA—H, (λmax=310nm) with a pKa value of 9.1. Cl2− reacts with a bimolecular rate constant of 3.5×107dm3mol−1s−1 forming solute radical cation (λmax=265nm). One-electron oxidation and reduction potentials for SPMA/SPMA+ and SPMA/SPMA− couples are estimated to be more than +1.6 and less than −1.9V, respectively.

Biological properties of copolymer of 2-hydroxyethyl methacrylate with sulfopropyl methacrylate.

Interaction of organism with non-toxic implanted polymers depends on the physicochemical properties of the implant surface, which influence the adsorption of bioactive proteins and subsequently adhesion and growth of cells. The synthetic hydrogels are known as poorly adhesive surfaces. In this study we demonstrated the adsorption of albumin, fibrinogen, fibronectin, basic fibroblast growth factor, heparin-binding epidermal growth factor-like growth factor and epidermal growth factor to poly(2-hydroxyethyl methacrylate) (pHEMA) and copolymer of 2-hydroxyethyl methacrylate (HEMA) and potassium salt of 3-sulfopropyl methacrylate (SPMAK). The adhesion and growth of 3T3 cells and human keratinocytes on surface of these polymers was tested without and with pretreatment of polymers with heparin-binding epidermal growth factor-like growth factor. The adhesion of mixture of human granulocytes and monocytes to these surfaces was also tested. The strips of both polymers were subcutaneously and intracerebrally implanted into the rat and the extent of foreign body reaction and brain biocompatibility was evaluated. The results showed the extensive adsorption of basic fibroblast growth factor and heparin-binding epidermal growth factor-like growth factor to copolymer containing SPMAK. However the adhesion (and growth) of cells to this type of copolymers was very low. Preadsorption of human plasma to pHEMA clearly stimulated the leukocyte adhesion in contrary to copolymer containing SPMAK. The extent of foreign-body reaction was significantly higher against the pHEMA compared to tested copolymer p(HEMA-co-SPMAK). In conclusion, the tested copolymer was a poorly adhesive substrate that is only poorly recognized by the non-specific immunity, although the adsorption of basic growth factors to this substrate is highly significant. Both polymers were well tolerated by the brain tissue. The phenotype of surrounding neurons was more close to the control neurons in the brain tissue surrounding the p(HEMA-co-SPMAK) implants.

Vesicles prepared from amphiphilic copolymers

Two amphiphilic monomers from aspartic acid, N-methacryloyl dihexadecyl l-aspartate (A16-MA) and N-itaconyl dioctadecyl l-aspartate (A16-I) were synthesized. Three kinds of amphiphilic copolymers were obtained by copolymerization of A16-MA with hydroxyethyl methacrylate (HEMA) and 3-sulfopropyl methacrylate potassium salt (SPMAP) respectively and of A16-I with HEMA. The aggregation behavior of the two monomers and three copolymers were examined in an aqueous system. A16-MA and its copolymers with HEMA are very difficult to disperse in water to form regular aggregates; however, copolymers from A16-MA and SPMAP can be dispersed in aqueous media as stable vesicles. Both A16-I and its copolymers with HEMA can be easily dispersed in aqueous medium and form vesicular assemblies. These bilayer membranes undergo a typical gel-to-liquid crystal phase transition as confirmed by differential scanning calorimetry. The phase transition temperatures of the copolymer vesicles shift to slightly higher temperatures with a broader phase transition temperature range. The permeability of A16-I vesicles was studied by monitoring the release of encapsulated fluorescent probes; however, the encapsulated probes cannot be retained for very long in the vesicles prepared from amphiphilic copolymers.

"Emulsifier-free" emulsion copolymerization of styrene and butylacrylate: particle size control with synthesis parameters

This paper presents the synthesis of film-forming particles with controlled diameters. The copolymerization of styrene and butylacrylate is realized by emulsion synthesis in the presence of potassium sulfopropylmethacrylate (SPM), an ionogenic monomer and sodium bicarbonate. The initiator, ammonium persulfate, and the SPM ensure the stabilization of particles. After the particles are washed, their diameters are measured by Dynamic Light Scattering (DLS) with a Zetasizer 3 (Malvern). The particle diameters are controlled by SPM concentration and the ionic strength of the medium. An increase of ionic strength, at constant [SPM], increases diameters, though an increase of [SPM], at constant ionic strength, decreases diameters. The experimental results are interpreted by two different modelizations, either by log–log equations like in the literature, or by semi-log and exponential equations. The latter ones give better modelization.

Methylmethacrylate sulfopropylmethacrylate copolymer nanoparticles for drug delivery: Part II: arecaidine propargyl ester and pilocarpine loading and in vitro release

Methylmethacrylate (MMA) sulfopropylmethacrylate (SPM) copolymer nanoparticles were prepared by free radical polymerization and the loading characteristics of the muscarinic agonists arecaidine propargyl ester (APE) and pilocarpine were investigated. The loading efficiency was mainly influenced by the concentration of the copolymer carrier system and followed Langmuir's adsorption equation. The in vitro drug release was mainly influenced by the composition of the acceptor phase used and the nanoparticle content of the donor phase. The bound drug was released from the carrier by competitive replacement by other ions from the binding sites of the particles. By this mechanism the nanoparticle system achieved a prolonged drug release, which was not the result of the increased viscosity at higher nanoparticle concentrations.

Methylmethacrylate sulfopropylmethacrylate copolymer nanoparticles for drug delivery: Part III: Evaluation as drug delivery system for ophthalmic applications

Copolymer nanoparticles were investigated as carrier systems for the topical ophthalmic application of the muscarinic agonists arecaidine propargyl ester (APE) and (S)-(+)-aceclidine in rabbits and compared to conventional eye drop preparations. The copolymer nanoparticles were prepared by free radical polymerization of methylmethacrylate (MMA) and sulfopropylmethacrylate (SPM). The in-vivo activity of the drug-containing carrier systems was tested by the measurement of the miotic effect observed after local administration in rabbits. It has been found that the copolymer nanoparticles were able to produce a significant increase of the ocular APE bioavailability as determined by the area under the miosis-time-curve (AUC). The nanoparticle preparations were tolerated without any irritating effect in the rabbit eye. Besides the copolymer nanoparticles, different formulations containing bioadhesive or viscosity-enhancing polymers with and without additional nanoparticles were tested. The administration of APE-loaded copolymer nanoparticles was found to be equivalent in efficacy to solutions containing the soluble polymers without nanoparticles. The combination of the nanoparticles with bioadhesive polymers further increased the ocular drug bioavailability. Hyaluronic acid alone or in combination with copolymer nanoparticles was observed to be the most effective soluble polymer for ophthalmic application by enhancing the AUC of miosis-time-curve 2-fold. Similar effects induced by the carrier systems were obtained with (S)-(+)-aceclidine. However, the magnitude of the enhancement of the miotic effect that is achievable by the binding of the drug to nanoparticles over free drug is much more pronounced with the short acting drug APE than with (S)-(+)-aceclidine.

Preparation, characterization and cytotoxicity of methylmethacrylate copolymer nanoparticles with a permanent positive surface charge

Methylmethacrylate copolymer nanoparticles containing different cationic comonomers such as N-trimethylammoniumethylmethacrylate (TMAEMC), N-dimethylammoniumethylmethacrylate (DMAEMC), N-trimethylammoniumpropylmethylacrylamide (MAPTAC) or the anionic comonomer sulfopropylmethacrylate (SPM), respectively, were prepared by free radical polymerization. Particle size was determined by photon correlation spectroscopy (PCS), transmission and scanning electron microscopy (TEM, SEM), and surface charge by microelectrophoresis. Pure poly(methylmethacrylate) nanoparticles served as control. Depending on the method, mean diameters of permanently positively-charged nanoparticles MMA-TMAEMC and MMA-MAPTAC were 243 or 207 nm (PCS), 161 or 201 nm (TEM), and 158 or 197 nm (SEM), respectively. Zeta potential examined in demineralized water or NaCl solution was +63.4 or +32.1 mV for MMA-TMAEMC nanoparticles and +49.2 or +32.0 mV for MMA-MAPTAC nanoparticles, respectively. Cytotoxicity of nanoparticles was determined by MTT assay in three different cell cultures including human foreskin fibroblasts (HFF) and two monkey kidney cell lines MA-104 and Vero. Cell viability profiles of TMAEMC and MAPTAC containing nanoparticles were different, showing IC 50 values for MMA-TMAEMC nanoparticles of 189.6±11.4 μg/ml (MA-104), 110.9±3.1 μg/ml (Vero) and 27.2±4.0 μg/ml (HFF). Cell viability at maximum concentration of 500 μg/ml MMA-MAPTAC nanoparticles was 98.3% (Vero), 85.7% (MA-104), or 94.0% (HFF), respectively.

Molecular Recognition by Hydrogen Bonding in Polyelectrolyte Multilayers

AbstractFunctional polyanions were prepared by copolymerization of sulfopropyl acrylate and sulfopropyl methacrylate with monomers bearing triaminopyrimidine or barbituric acid functionalities, respectively. Functionalized polyelectrolyte multilayers were assembled from these copolymers by stepwise alternating adsorption with poly(choline methacrylate). These multilayers are suited for molecular recognition of substrates that are complementary to the functional groups incorporated. Thus, multilayers containing triaminopyrimidine moieties selectively bind barbituric acid, and vice versa, when exposed to solutions of the 1:1 complex of barbituric acid and triaminopyrimidine. The molecular recognition process was monitored by UV/Vis spectroscopy, time‐of‐flight secondary ion mass spectroscopy (ToF‐SIMS), and photoelectron spectroscopy (XPS). Remarkably, after successful recognition and binding of the complementary substrates to the multilayers, the stepwise layering could be continued.

A Designer's Polymer as an Oral Drug Carrier (Tablet) with Pseudo-Zero-Order Release Kinetics

A new synthetic polymeric material has been investigated as an oral controlled-release system. The water soluble polymer consists of a non-cross-linked, ionic polymer possessing sulfonate functional groups: poly(sulfopropyl methacrylate potassium-co- methyl methacrylate) (PSPMK/MMA). Drug–resin complexes were obtained by preparing an aqueous solution of the polymer to which propranolol HCl as a model drug was added. Using either dextrose or microcrystalline cellulose as a tablet binder did not cause any problems in fabricating a compact drug–resinate tablet. The release of propranolol HCl from drug–resinate tablets (2.5mm × 9.0mm, 10% dextrose) was pseudo-zero-order kinetics from the beginning to the end for over 21h. This was due to the greater contribution of drug release from the edge of the tablets. However, zero-order release tablets were obtained by increasing the radius to thickness ratio of the tablet to greater than 3.13. A mathematical model describing release kinetics from drug–resinate tablets predicted the effects of drug loading and the physical dimensions of the tablets by a heterogeneous dissociation/erosion-controlled mechanism. As the content of dextrose in the tablets increased, the dissociation/erosion rate constant (ko) increased due to the greater influx of water into the tablets along with counterions. As expected, the release rate was decreased as the stirring rate decreased from 100 to 50 rpm, resulting in the dissociation/erosion rate constant of 2.62–2.04mg/cm2 h, respectively. Therefore, this system has been proven to release drugs independent of the pH of simulated gastric/intestinal fluids (1.2 and 7.5) as well as the compression force of the tablet, which ranged from 1500 to 4400 lbs.

Methylmethacrylate sulfopropylmethacrylate copolymer nanoparticles for drug delivery. Part I: Preparation and physicochemical characterization

Methylmethacrylate (MMA) sulfopropylmethacrylate (SPM) copolymer nanoparticles were prepared by free radical polymerization. The conditions of preparation were varied with regard to the concentration of initiator and monomer, and copolymer composition. Nanoparticles with a yield greater than 80% were produced. The particles were characterized in terms of particle size, size distribution, particle charge (zetapotential) and molecular weight. The data were compared to pure polymethylmethacrylate (PMMA) nanoparticles. The copolymer composition was shown to influence particle size and particle charge. The influence of the total monomer amount in the polymerization medium on the particle size was characteristic up to a concentration of 2% depending on the solubility of MMA in water at the temperature of reaction. An increasing amount of total monomer led to particle sizes of 60–130 nm for low monomer concentrations (0.5%), depending on the proportion of SPM (0–10%), to 120–280 nm for higher total monomer concentrations (greater than 2%). Surface charge as well as particle size were influenced mainly by the proportion of the comonomer SPM in the copolymer. The negative surface charge increased from - 52 mV for pure PMMA nanoparticles to − 80mV for the copolymer particles with an SPM content of 10%. In the same range of 0–10%), SPM of the total monomer, the particle sizes decreased from 187 to 100 run. The concentration of the initiator up to a concentration of 0.3% showed no effect on the particle size of the resulting nanoparticle suspension. Higher concentrations led to intolerably large variability in the polymerization process.