Environmentally Friendly o-Cresol-Furfural-Formaldehyde Resin as an Alternative to Traditional Phenol-Formaldehyde Resins for Paint Industry.

This paper describes studies on the preparation of an o-cresol-furfural-formaldehyde resin in the presence of an alkaline catalyst and its modification with n-butanol or 2-ethylhexanol. The novelty of this research is to obtain a furfural-based resin of the resole type and its etherification. Such resins are not described in the literature and also are not available on the market. The obtained resin based on furfural, which can be obtained from agricultural waste, had a low minimum content of free o-cresol < 1 wt.%, furfural < 0.1 wt.%, and formaldehyde < 0.1 wt.%. The resin structure was characterized by mass spectrometry (ESI-MS), FT-IR, and NMR spectroscopy, which showed the presence of hydroxymethylene groups in the resin before modification and alkyl groups derived from n-butanol and 2-ethylhexanol after modification. The etherified resins had a lower viscosity and were more flexible (DSC) than the resin before modification and they can be used as an environmentally friendly, safe, and sustainable alternative to traditional phenol-formaldehyde resins in the paint industry. They demonstrate the ability to create a protective coating with good adherence to metal substrates and an excellent balance of flexibility and hardness.

Poly(sebacic acid) microparticles loaded with azithromycin as potential pulmonary drug delivery system: Physicochemical properties, antibacterial behavior, and cytocompatibility studies.

Recurrent bacterial infections are a common cause of death for patients with cystic fibrosis and chronic obstructive pulmonary disease. Herein, we present the development of the degradable poly(sebacic acid) (PSA) microparticles loaded with different concentrations of azithromycin (AZ) as a potential powder formulation to deliver AZ locally to the lungs. We characterized microparticle size, morphology, zeta potential, encapsulation efficiency, interaction PSA with AZ and degradation profile in phosphate buffered saline (PBS). The antibacterial properties were evaluated using the Kirby-Bauer method against Staphylococcus aureus. Potential cytotoxicity was evaluated in BEAS-2B and A549 lung epithelial cells by the resazurin reduction assay and live/dead staining. The results show that microparticles are spherical and their size, being in the range of 1-5 µm, should be optimal for pulmonary delivery. The AZ encapsulation efficiency is nearly 100 % for all types of microparticles. The microparticles degradation rate is relatively fast - after 24 h their mass decreased by around 50 %. The antibacterial test showed that released AZ was able to successfully inhibit bacteria growth. The cytotoxicity test showed that the safe concentration of both unloaded and AZ-loaded microparticles was equal to 50 µg/ml. Thus, appropriate physicochemical properties, controlled degradation and drug release, cytocompatibility, and antibacterial behavior showed that our microparticles may be promising for the local treatment of lung infections.

Highly Branched Betulin Based Polyanhydrides for Self-Assembled Micellar Nanoparticles Formulation.

Polyanhydrides based on betulin are promising materials for use in controlled drug delivery systems. Due to the broad biological activity of betulin derivatives and lack of toxicity in vitro and in vivo, these polymers can be used both as polymeric prodrug and as carriers of other biologically active compounds. In this study, we develop a novel amphiphilic branched polyanhydrides synthesized by the two-step melt polycondensation of betulin disuccinate (DBB) and a tricarboxylic derivative of poly(ethylene glycol) (PEG_COOH). DBB and PEG_COOH were used as the hydrophobic and hydrophilic segments, respectively. The content of DBB in copolymers was from 10 to 95 wt%. Copolymers were assessed for their cytostatic activity against various cancer cell lines. Compared to linear DBB and PEG-based polyanhydrides, the branched polyanhydrides exhibited higher anticancer activity. The obtained polymers were able to self-assemble in water to form micelles with hydrodynamic diameters from 144.8 to 561.8 nm. and are stable over a concentration range from 12.5 µg/mL to 6.8 mg/mL. The formed micelles were found to be spherical in shape using a scanning electron microscope. It was found that the structure and composition of polyanhydrides affected the hydrodynamic diameter of the micelles. The branched betulin-based polyanhydrides have the potential to serve as biodegradable polymer prodrugs or carriers for other bioactive compounds.

Emulsion Explosives: A Tutorial Review and Highlight of Recent Progress.

Emulsion explosives (EE) have been commercially available in various forms for over 50 years. Over this period, the popularity and production technology of this class of energetic materials have been developing constantly. Despite this rapid rise to prominence and, in some applications, prevalence over traditional energetic materials, remarkably little information is available on the physicochemical and energetic properties of these materials and factors affecting those properties. This work is dedicated to presenting the fundamental information relevant to the features, properties and applications of EEs, while highlighting the most significant recent progress pertaining to those materials. Particular emphasis has been given to providing information about the types, composition, modifications and detonation parameters of EEs, as well as to highlighting the less obvious, emerging applications of EEs.

Biodegradable and Bioactive Carriers Based on Poly(betulin disuccinate-co-sebacic Acid) for Rifampicin Delivery.

This paper describes the preparation and characterization of polymer-drug systems based on polymeric microspheres obtained from poly(betulin disuccinate-co-sebacic acid). The active compound that was coupled to the betulin-based carriers was rifampicin (RIF), an ansamycin drug used in the treatment of tuberculosis. Poly(betulin disuccinate-co-sebacic acid) microspheres were prepared using a solvent evaporation technique from copolymers obtained by polycondensation of betulin disuccinate (DBB) and sebacic acid (SEB). The content of sebacic acid in the copolymers was 20, 40, 60 and 80 wt%, respectively. Small and large rifampicin-loaded microspheres were obtained for each of the copolymers. The initial amount of drug was 10, 30 or 50 wt%, based on the weight of the polymer. Particles obtained in this study were round in shape with diameter in the range of 2-21 µm and of orange to red colour originating from rifampicin. The RIF encapsulation efficacy varied from 7% to 33%. Drug loading varied from 2% to 13% and increased at a higher RIF ratio. The highest degree of drug loading was observed for large particles, in which the initial amount of drug (at the particle preparation stage) was 50 wt%. Microspheres prepared from betulin-based polyanhydrides may have significant applications in drug delivery systems. The concentration of loaded drug was enough to obtain bactericidal effects against reference S. Aureus ATCC 25923 bacteria.

Novel Sensitizing Agent Formulation for Bulk Emulsion Explosives with Improved Energetic Parameters.

Bulk emulsion explosives, although they are very convenient and safe to use, also have disadvantages, with the main one being the relatively low power in relation to cartridged emulsion explosives or classic nitroesters (e.g., dynamites). Therefore, materials of this type currently have only limited use. In addition, these materials are characterized by the variability of blasting parameters over time from loading into the blasthole, which is closely dependent on the utilised mining method of the mine, which makes it difficult to precisely control the fragmentation. The industry is trying to respond to the demand for bulk emulsion explosives with increased energy and improved parameter stability, but so far it has not been possible to do so in a safe and effective way. Methods of improving blasting parameters mainly rely on additives to oxidant solutions during production, which creates additional risks at the production stage, as it involves handling hot and concentrated ammonium nitrate solutions, for which there are known cases of uncontrolled decomposition of such solutions, even leading to an explosion. This paper presents a method of improving the thermodynamic parameters and the stability of the sensitization reaction without the need for changes in the oxidant solution.

Bioactive Betulin and PEG Based Polyanhydrides for Use in Drug Delivery Systems.

In the course of this study, a series of novel, biodegradable polyanhydrides based on betulin disuccinate and dicarboxylic derivatives of poly(ethylene glycol) were prepared by two-step polycondensation. These copolymers can be used as carriers in drug delivery systems, in the form of microspheres. Betulin and its derivatives exhibit a broad spectrum of biological activity, including cytotoxic activity, which makes them promising substances for use as therapeutic agents. Microspheres that were prepared from betulin based polyanhydrides show promising properties for use in application in drug delivery systems, including inhalation systems. The obtained copolymers release the active substance-betulin disuccinate-as a result of hydrolysis under physiological conditions. The use of a poly(ethylene glycol) derivative as a co-monomer increases the solubility and bioavailability of the obtained compounds. Microspheres with diameters in the range of 0.5-25 µm were prepared by emulsion solvent evaporation method and their physicochemical and aerodynamic properties were analyzed. The morphological characteristics of the microspheres depended on the presence of poly(ethylene glycol) (PEG) segment within the structure of polyanhydrides. The porosity of the particles depended on the amount and molecular weight of the PEG used and also on the speed of homogenization. The most porous particles were obtained from polyanhydrides containing 20% wt. of PEG 600 by using a homogenization speed of 18,000 rpm.

Anticancer activity of functional polysuccinates with N-acetyl-cysteine in side chains.

The synthesis and characteristics of functional polyesters with a potential anticancer activity have been described, followed by a post-modification process of biologically active polymers. First, biodegradable functional polysuccinates possessing pendant allyl groups, that are susceptible to thiol-ene reaction, were obtained by polyaddition of succinic anhydride and allyl glycidyl ether. The functionality of such polyesters was regulated by replacing a part of unsaturated glycidyl ether with saturated ones. Polymers containing 20-100% mers with allyl groups were reacted with N-acetyl-cysteine (NAC). The use of simple click reaction allowed obtaining polyesters containing different amounts of N-acetyl-cysteine in side chains. The thus obtained polymers with a molecular weight of several thousand are characterized by solubility in methanol as opposed to their initial precursors. Modified polyesters show no toxicity to normal human keratinocytes (HaCaT) cells, similar to the NAC in normal human fibroblasts (NHDF), whereas the anticancer activities were observed against squamous carcinoma (SCC-25), and melanoma (Me45) cells. A standard colorimetric assay (MTS), to assessing cells viability and cytotoxicity of tested compounds, was performed against NHDF for NAC, HaCaT, SCC-25, and Me45 cells, within 24-144 h long-term expositions. Neither contact with NAC alone, and tested materials, nor long incubation decreased normal cell viability or induced inflammation. That reassumed the potential of anticancer activities of tested materials, with the tendency to visible selectivity against cancer cell lines in vitro, confirmed with live microscopic imaging against the Me45 cell line.

Novel polymeric derivatives of betulin with anticancer activity.

In order to provide novel polymeric biomaterials for chemotherapeutic purposes, in this paper we described the synthesis and the characterization of the physicochemical properties of a betulin-based polyanhydride exhibiting anti-cancer effects. The polyanhydride was obtained by a melt polycondensation of a disuccinate betulin (3,28-di-O-succinyl betulin), and was thoroughly characterized through 1H NMR and 13C NMR spectroscopies, correlation spectroscopy, heteronuclear single quantum correlation, size exclusion chromatography, differential scanning calorimetry and FT-IR spectroscopy. It was confirmed, that the obtained polyanhydride undergoes hydrolytic degradation, releasing disuccinate betulin as a degradation product. Polyanhydride of a disuccinate betulin was tested for cytostatic activity against a wide range of cancer cell lines (HeLa, MCF-7, A-549, U-87MG, KB and HepG2), proving its efficiency in inhibiting the growth of selected cancer cells. To realize the concept of an easily administrated drug release system, polyanhydride was fabricated in a form of micro- (1-30 µm) and nanospheres (∼400 nm) by using an emulsion solvent evaporation method. The micro- and nanospheres were characterized by SEM.

The novel semi-biodegradable interpenetrating polymer networks based on urethane-dimethacrylate and epoxy-polyester components as alternative biomaterials.

PURPOSE: This paper presents the pilot study aimed at the development of new full interpenetrating polymer networks based on urethane- dimethacrylate and biodegradable epoxy-polyester as the proposition of new biomaterials with gradually emerging porosity. METHODS: The urethane-dimethacrylate monomer was obtained from 4,4'-methylenebis(phenyl isocyanate) and tetraethylene glycol monomethacrylate. The redox-initiating system was employed for its radical polymerization. The epoxy-polyester was produced by oxidation of the polyester, synthesized from succinic anhydride and allyl glicydyl ether. It was cured in a step-growth process with biogenic, aliphatic amine - spermidine. The mixtures of both monomers with adequate curing agents were room temperature polymerized. The hardened materials were characterized for damping behavior and dynamic modulus, hardness, water sorption, the course of hydrolytic degradation as well as the morphology - before and during the degradation process. RESULTS: The cured materials revealed the nonporous, dense morphology. In the hydrolytic environment, the epoxy-polyester network degraded and the porous urethane-dimethacrylate scaffold remained. The epoxy-polyester appeared to prevent the urethane-dimethacrylate from attaining a high degree of conversion, even if the polymerization rate and the molecular mobility of the latter one are higher than those of the epoxy-polyester. The most homogeneous material with the best physico-mechanical properties was obtained when the urethane-dimethacrylate content was smaller than the epoxy-polyester content, respectively 25 and 50 wt%. CONCLUSIONS: The system presented in this work could be useful in tissue engineering, where at the beginning of the tissue regeneration process it would meet the implant mechanical properties and then would deliver its porosity, facilitating the tissue regeneration process.

Novel bioactive polyester scaffolds prepared from unsaturated resins based on isosorbide and succinic acid.

In this study new biodegradable materials obtained by crosslinking poly(3-allyloxy-1,2-propylene succinate) (PSAGE) with oligo(isosorbide maleate) (OMIS) and small amount of methyl methacrylate were investigated. The porous scaffolds were obtained in the presence of a foaming system consisted of calcium carbonate/carboxylic acid mixture, creating in situ porous structure during crosslinking of liquid formulations. The maximum crosslinking temperature and setting time, the cured porous materials morphology as well as the effect of their porosity on mechanical properties and hydrolytic degradation process were evaluated. It was found that the kind of carboxylic acid used in the foaming system influenced compressive strength and compressive modulus of porous scaffolds. The MTS cytotoxicity assay was carried out for OMIS using hFOB1.19 cell line. OMIS resin was found to be non-toxic in wide range of concentrations. On the ground of scanning electron microscopy (SEM) observations and energy X-ray dispersive analysis (EDX) it was found that hydroxyapatite (HA) formation at the scaffolds surfaces within short period of soaking in phosphate buffer solution occurs. After 3h immersion a compact layer of HA was observed at the surface of the samples. The obtained results suggest potential applicability of resulted new porous crosslinked polymeric materials as temporary bone void fillers.

In vitro release of model compounds with different hydrophilicity from poly(ester-anhydride) microspheres.

Poly(ester-anhydride) microspheres were prepared using emulsion solvent evaporation technique from two copolymers obtained by polycondensation of sebacic acid (SBA) and oligo(3-allyloxy-1,2-propylene succinate) terminated with carboxyl groups (OSAGE). The SBA content in copolymers was 90 or 70 w/w %, respectively. The size of microspheres obtained was in the range of 2-4 microm (small microspheres) or 12-31 microm (large ones) and depended on stirring conditions used in emulsion formulation process, as well as on concentration of polymer solution used. Poly(ester-anhydride) microspheres were loaded with three model compounds (rhodamine B, p-nitroaniline and piroxicam) with different water solubility. The loading efficiency was dependent on kind of model compound, polymer composition and size of microparticles. Each of three model compounds also exhibited different release profiles. Rhodamine was released very quickly. The release of p-nitroaniline was more prolonged, but showed only little dependence on microsphere size and polymer composition, whereas the piroxicam-loaded microspheres exhibited the most interesting release profile, showing that release rate as well as transport mechanism can be adjusted by changing microsphere size and poly(ester-anhydride) compositions.

Preliminary studies on the hydrolytic degradation and biocompatibility of poly(3-allyloxy-1,2-propylene succinate).

In the present paper the synthesis and selected properties of functional aliphatic poly(3-allyloxy-1,2-propylene succinate) (PSAGE) are described. This polyester was synthesized by melt co-polymerization of succinic anhydride and allyl glycidyl ether in the presence of benzyltrimethylammonium chloride as catalyst. The chain structure of PSAGE and its end-groups was characterized by MALDI-TOF mass spectrometry. It was found that PSAGE undergoes hydrolytic degradation in phosphate buffer solution (pH 7.41) at 37 degrees C and, unexpectedly, the dependence of mass loss on immersion time turned out to be linear in the first 12 weeks, similar to hydrophobic polyanhydrides. The polysuccinate of 3600 Da was tested on rat alveolar macrophage cell line using the MTT assay to determine its cytotoxicity, as well as the NO production level, which is an indicator of cell activation. The data obtained show that PSAGE is non-toxic, and that the viability of cells ranges from 86 to 100%. The obtained results reveal the potential applicability of PSAGE as a component of biomaterials or as polymeric drug carrier.

Characterization of new biodegradable bone cement compositions based on functional polysuccinates and methacrylic anhydride.

New biodegradable poly(3-allyloxy-1,2-propylene)succinate-based materials were obtained by cross-linking poly(3-allyloxy-1,2-propylene)succinate (PSAGE) with methyl methacrylate (MMA) and methacrylic anhydride (MAAH). The aim of this study was to examine the influence of MAAH/MMA ratio and incorporation of biphasic calcium phosphate (BCP) filler on the maximum curing temperature, setting time, compressive strength and modulus of the cured materials, as well as on their hydrolytic degradation. The latter was characterized by determination of the weight loss and observation of changes in samples morphology by SEM. The maximum temperature during cross-linking was found to decrease with increasing MAAH content. The setting time was affected strongly by the concentration of double bonds and was rapidly shortened with its increase. The compressive strength and compressive modulus values increased with increasing MAAH/MMA ratio. Moreover, addition of bioactive mineral filler (BCP) improves significantly mechanical properties of these materials. On the other hand, it slows down their hydrolytic degradation.

Evaluation of oligo(ethylene glycol) dimethacrylates effects on the properties of new biodegradable bone cement compositions.

New injectable, in situ curable liquid formulations consisting of biodegradable aliphatic polyester, i.e., poly(3-allyloxy-1,2-propylene)succinate (PSAGE), methyl methacrylate (MMA), and hydrophilic oligo(ethylene glycol) dimethacrylates (OEGDMA) were investigated. The effect of MMA/OEGDMA ratio, OEGDMA molecular weight, i.e., the length of oligooxyethylene fragments, on the maximum curing temperature, setting time, compressive strength and modulus of the cured materials as well as their hydrophilicity were examined. The latter was characterized by determination of equilibrium water content and static water contact angle. The maximum temperature during crosslinking was found to decrease with increasing OEGDMA molecular weight and decreasing MMA/OEGDMA ratio. The setting time was affected strongly by the concentration of double bonds and was rapidly shortened with its increase. The compressive strength and compressive modulus values decreased with increasing OEGDMA molecular weight and decreasing MMA/OEGDMA ratio. Poly(3-allyloxy-1,2-propylene succinate).