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The purpose of this investigation was to develop small microspheres for delivering antimycobacterial drugs to infected host macrophages. Rifampicin-based microparticles were prepared. The drug was covalently linked to acrylic moieties to obtain a polymerizable derivative for the preparation of materials useful as drug delivery systems that then were loaded with isoniazid acting in synergy with rifampicin. Their antitubercular activity was determined in vitro. Fourier transform infrared spectroscopy confirmed hydrogel structure. Morphological analysis showed microparticles with spherical shape and homogeneous surface. In vitro release studies were performed in media simulating physiologic pH (7.4) and endosomal of alveolar macrophages pH (5.2). A similar amount of isoniazid was delivered within the first 6 h at both pHs, while a smaller amount of the drug was delivered at pH 7.4 in the last phase of the study. In vitro antitubercular activity showed a behavior comparable to that of rifampicin and isoniazid free. Bioactive swelling matrices, showing a high swelling degree into a medium miming intra alveolar environment, were obtained. They could be applied for their antitubercular activity., (Copyright © 2011 Wiley Periodicals, Inc.)

pH-sensitive bovine serum albumin (BSA) hydrophilic microspheres were prepared by free radical polymerization of methacrylate derivatized BSA and methacrylic acid sodium salt. Incorporation of both monomers in hydrogels was confirmed by Fourier transform infrared spectroscopy. Morphological analysis by scanning electron microscopy showed spherical shape and porous surface of all prepared samples. The microspheres showed high water affinity at neutral pH values and a narrow dimensional distribution. Network density of hydrogels depends on derivatization degree (DD%) of BSA and/or concentration of modified BSA in the polymerization feed. In order to employ the prepared samples such as pH-sensitive hydrogels, in vitro release studies, in media simulating biological fluids, were performed using diflunisal (DF) and beta-propranolol (PR) as model drugs. Experimental data showed that the release profiles depend on drug-matrix interactions and diffusional limitation awardable to crosslinking degree of microparticles. beta-Propranolol is quickly released at pH 1.0 and a complete release after 1 h at pH 6.8 was observed. In the case of diflunisal pH-sensitive release was observed. At pH 1.0 low amounts of drug were released (w/w<10% after 2 h). When the pH is 6.8, the diflunisal release increased in the amount (w/w>75% after 24 h).

Objectives This study concerns the preparation and characterization of microspheres based on a mixture of triterpene saponins, from Physospermum verticillatum (Waldst & Kit), as a carrier for the specific release of gemcitabine. Methods Triterpene saponins were derivatized with acrylic acid. The obtained polymerizable product was characterized by Fourier transform infrared to confirm the ester linkage. Then, spherical microparticles were prepared by suspension radical copolymerization and impregnated with gemcitabine. Key findings Microspheres exhibited a mean diameter of 2.7 μ. The swelling studies showed that particles swell most at pH 6.2, typical of the tumour pathology, than at pH 7.4, miming physiological conditions. The microspheres were loaded with gemcitabine ( LE 72.2%). Their release profile showed an initial dot of around 24% and a further release for 24 h. Conclusions This carrier could be potentially release the drug in the lung, as a function of different pHs between tumour cells and healthy, reducing the systemic drug toxicity, allowing the reduction of the doses number, increasing the drug half-life and eliminating the problems related to the fast clearance of gemcitabine administration. [ABSTRACT FROM AUTHOR]

Novel molecularly imprinted polymers (MIPs) suitable for the electroresponsive release of diclofenac were synthesized by precipitation polymerization in the presence of carbon nanotubes (CNTs). Both conventional and electroresponsive imprinted polymers were synthesized with methacrylic acid as the functional monomer and ethylene glycol dimethacrylate as the crosslinker. Preliminary experiments were performed to fully characterize the conventional MIPs and composite materials in terms of their morphological properties, recognition behavior, and electric resistivity. In vitro release experiments were performed in aqueous media to elucidate the ability of the MIPs and spherical imprinted polymers doped with CNTs to release the loaded template in a sustained manner over time in comparison to the that of the corresponding nonimprinted materials. Furthermore, a 20-V direct-current voltage was applied through the releasing media to evaluate how the electric field influenced the drug release to demonstrate the suitability of the proposed macromolecular system as an electroresponsive drug-delivery device. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 130: 829-834, 2013 [ABSTRACT FROM AUTHOR]

Novel stimuli-responsive hydrophilic microspheres were prepared by free radical polymerization of hydroxyethyl methacrylate (HEMA) and methacrylic acid (MA), as hydrophilic monomers, and N-isopropylacrylamide (NIPAAm) and N, N′-ethylenebisacrylamide (EBA), as thermo-sensitive monomer and crosslinker, respectively. Hydrophilic comonomers were introduced in the macromolecular network to synthesize materials with tunable thermal behavior. In addition, by introducing in the polymerization feed both a hydrophilic and a pH-sensitive monomer, such as MA, dual stimuli-responsive (pH and temperature) hydrogels were synthesized. The incorporation of monomers in the network was confirmed by infrared spectroscopy, while the network density and the shape of hydrogels was found to strictly depend on the concentration of monomers in the polymerization feed. Thermal analyses showed negative thermo-responsive behavior with pronounced water affinity of microspheres at a temperature lower than lower critical solution temperature (LCST). In our experiment, the LCST values of the hydrogels were in the range 34.6-37.5°C, close to the body temperature, and the amount of hydrophilic moieties in the polymeric network allows to collect shrinking/swelling transition temperatures higher than the LCST of NIPAAm homopolymers. In order to test the preformed materials as drug carriers, diclofenac diethylammonium salt (DDA) was chosen and drug entrapment percent was determined. Drug release profiles, in media at different temperature and pH, depend on hydrogels crosslinking degree and drug-bead interactions. By using semi-empirical equations, the release mechanism was extensively studied and the diffusional contribute was evaluated. Copyright © 2010 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

This paper deals with the synthesis of thermoresponsive microspheres with proteic structure exhibiting a transition temperature close to the body temperature. The hydrogels were synthesized by free radical polymerization of methacrylate Bovine Serum Albumin (BSA-MA) as crosslinker, and 2-hydroxyethyl methacrylate (HEMA) and/or N-isopropylacrylamide (NIPAAm), as hydrophilic and thermoresponsive monomers, respectively. The modification of the hydrophilic/hydrophobic balance in the polymerization feed allows to modulate the volume phase transition temperature of the macromolecular network. The hydrogels were characterized by infrared spectroscopy and thermal analyses, which showed negative thermoresponsive behavior for all compositions and, by increasing the content of the hydrophilic moieties in the network, the transition temperature was ranged from 34.2 to 36.8°C. To test the preformed materials as drug carriers, diclofenac diethyl ammonium salt was chosen and drug entrapment percent was determined. Drug release profiles, in media at different temperature, depend on the crosslinking degree and on the composition of the hydrogels. By using semiempirical equations, the release mechanism was extensively studied and the diffusional contribute evaluated. The physic-chemical characteristics of thermoresponsive materials confirm the applicability of the microspheres as drug delivery device. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011 [ABSTRACT FROM AUTHOR]

Thermal and dual stimuli-responsive microspheres (pH and temperature) were prepared by free radical polymerization of methacrylate bovine serum albumin (BSA-MA) as cross-linker and sodium methacrylate (NaMA) and/or N-isopropylacrylamide (NIPAAm), as hydrophilic/pH-sensitive and thermo-responsive monomers, respectively. Microgels were characterized by infrared spectroscopy, morphological analysis, particle size distribution and determination of swelling properties. The network density and the shape of the microgels were found to depend on the concentration of the reactive species in the polymerization feed. Thermal analyses were performed to determine lower critical solution temperature values, which become close to the body temperature by increasing the content of the hydrophilic moieties in the network. In order to test the preformed materials as drug carriers, in vitro release studies of Diclofenac diethyl ammonium salt were performed. For all the co-polymers, a predominant drug release in the collapsed state was observed, while below the microgel transition temperature, a drug release through the swollen network occurs. The data recorded during the release tests demonstrated that the pH of the surrounding environment influences the drug release more than the temperature of the imbibing medium. [ABSTRACT FROM AUTHOR]

A novel, simple synthetic strategy for the preparation of crosslinked polymers with significant antioxidant properties is proposed. Ferulic acid (FA), a well‐known antioxidant compound, due to its reactivity toward free radical process, was inserted into a polymeric network with methacrylic acid (MAA) and ethylene glycole dimethacrylate acting as comonomer and crosslinker, respectively. All the reactants were simultaneously mixed in the polymerization feed and one‐pot radical reaction was carried out. Irregular microparticles were prepared by bulk polymerization and microspheres by precipitation polymerization. The materials were characterized by nuclear magnetic resonance–magic angle spinning (NMR‐MAS) studies, to verify effective FA insertion into polymeric networks, and by morphological, dimensional analyses, and water absorption measurement to study their superficial and swelling properties, respectively. Antioxidant properties of materials were evaluated by linoleic acid emulsion system–thiocyanate assay, determination of scavenging activity on DPPH radicals, determination of available phenolic groups in polymeric matrices, and determination of total antioxidant capacity. Copyright © 2009 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

Abstract: The main target of this study was the preparation, characterization and in vitro activities evaluation of microspheres curcumin-based able to incorporate azathioprine, useful for psoriasis treatment. Curcumin was derivatized with acryloyl chloride in order to introduce polymerizable groups in its structure. The obtained polymerizable drug was characterized by Fourier transform infrared (FT-IR), to confirm ester linkages, and by 1H-NMR, to establish the functionalization degree. The ability of curcumin derivative to inhibit cell proliferation, in human breast cancer cells, gave an IC50 value for viability of 20μM. Acrylated curcumin also showed a strong antioxidant activity against lipid peroxidation induced in rat liver microsomal membranes. Then, spherical microparticles, based on curcumin derivative, were prepared by suspension radical copolymerization. The obtained microparticles were characterized by FT-IR spectroscopy, dimensional and morphological analysis. Particle size investigation revealed a mean diameter of around 5.8μm. Microspheres showed a very good swelling behavior in simulating intestinal fluids. Their azathioprine loading efficiency, determined by spectophotometric analysis was equal to 80%. Release profile of azathioprine showed an initial dot of around 60% and a further release for 24h. [Copyright &y& Elsevier]

Abstract: The aim of this work is to design, prepare and characterize l-lysine based prodrugs capable of targeting 6-mercaptopurine to the colon, an anti-tumor and immunosuppressant drug, and 5-aminosalicylic acid (5-ASA), drug of choice for inflammatory bowel disease (IBD). More specifically, Nɛ-feruloyl-S-(6-purinyl)-l-lysine and Nɛ-acryloyl-S-(6-purinyl)-l-lysine were synthesized and then characterized by FT-IR, 1H-NMR and GC/MS spectroscopies. The ability of feruloyl derivative in inhibiting lipid peroxidation in rat liver microsomal membranes, induced in vitro by tert-butyl hydroperoxide as source of free radicals, was evaluated. Moreover, Nɛ-acryloyl-S-(6-purinyl)-l-lysine, polymerizable prodrug, was used to microspheres realization for 5-ASA release. These lasts, obtained by emulsion inverse technique, were characterized by light scattering and scanning electron microscopy (SEM) analysis. The microspheres equilibrium swelling degree was evaluated and showed good swelling behaviour in simulating colonic fluids. Results confirm the possibility that the application range of l-lysine prodrug can be extended to the treatment of intestinal diseases whose conventional therapy envisages medications with serious side effects that, thanks to this new strategy, can be minimized in an optimal way. [Copyright &y& Elsevier]

Abstract: In this paper, a novel class of microspheric hydrogels was synthesized by grafting of N-isopropyacrylamide (NIPAAm) with gelatin. The possibility of inserting commercial gelatin in a crosslinked structure bearing thermo-sensitive moieties, by radical process, represents an interesting innovation that significantly improves the device performance, opening new applications in biomedical and pharmaceutical fields. This synthetic approach allows a modification of the polymeric network composition, producing hydrogels with suitable physico-chemical properties and a transition temperature higher than NIPAAm homopolymers. The incorporation of monomers into the network was confirmed by infrared spectroscopy, and the composition of the polymerization feed was found to strictly influence the network density and the shape of hydrogels. Thermal analyses showed negative thermo-responsive behaviour with shrinking/swelling transition values in the temperature range 34.6–34.8°C, according to the amount of the hydrophilic portions in the network. In order to test the preformed materials as drug carriers, diclofenac sodium salt was loaded into the spherical microparticles. After the determination of the drug entrapment percent, drug release profiles in media at different temperature were analysed. By using semi-empirical equations, the release mechanism was extensively studied and the diffusional contribution was evaluated. [ABSTRACT FROM AUTHOR]

Abstract: The aim of this study was to investigate the possibility to synthesize new chelating polymeric microspheres owing immobilized biocompatible agent as chelating functional groups and to evaluate their performance in metal ions removal from aqueous solution. The microparticles were synthesized via precipitation polymerization of 4-O-(4-vinylbenzyl)-myo-inositol 1,3,5-orthoformate with ethylene glycol dimethacrylate (EGDMA) and subsequent exhaustive phosphorylation of myo-inositol groups using phosphoric acid. Spherical geometry with monodisperse nature of the polymeric microparticles was confirmed by scanning electron micrographs (SEM) and dimensional analysis. A large surface area of the microspheres provided a maximum interaction of metal ions and the chelating functional groups on the surface. Absorption capacity of the beads for the selected metal ions, i.e., Cu(II), Ni(II), Fe(III), was investigated in detail in aqueous solution at pH 5.0 utilizing UV/Vis spectroscopy. This study showed that the macromolecular systems are very effective in chelating these metal ions and the affinity order of the microbeads toward metal ions is: Fe(III)>Ni(II)>Cu(II). The chelating beads can be easily regenerated by 1.0M HNO3 with high effectiveness. These features make the synthesized beads a potential candidate for metal ions removal at high capacity. [Copyright &y& Elsevier]