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The aim of this study was to examine homopolymeric poly(N-isopropylacrylamide), p(NIPAM), hydrogels cross-linked with ethylene glycol dimethacrylate as carriers for sulfanilamide. Using FTIR, XRD and SEM methods, structural characterization of synthesized hydrogels before and after sulfanilamide incorporation was performed. The residual reactants content was analyzed using the HPLC method. The swelling behavior of p(NIPAM) hydrogels of different crosslinking degrees was monitored in relation to the temperature and pH values of the surrounding medium. The effect of temperature, pH, and crosslinker content on the sulfanilamide release from hydrogels was also examined. The results of the FTIR, XRD, and SEM analysis showed that sulfanilamide is incorporated into the p(NIPAM) hydrogels. The swelling of p(NIPAM) hydrogels depended on the temperature and crosslinker content while pH had no significant effect. The sulfanilamide loading efficiency increased with increasing hydrogel crosslinking degree, ranging from 87.36% to 95.29%. The sulfanilamide release from hydrogels was consistent with the swelling results—the increase of crosslinker content reduced the amount of released sulfanilamide. After 24 h, 73.3–93.5% of incorporated sulfanilamide was released from the hydrogels. Considering the thermosensitivity of hydrogels, volume phase transition temperature close to the physiological temperature, and the satisfactory results achieved for sulfanilamide incorporation and release, it can be concluded that p(NIPAM) based hydrogels are promising carriers for sulfanilamide.

This work aimed to evaluate chemical profile, antioxidant activity and topical application safety of the raw Osage orange (Maclura pomifera (Raf.) Schneid) fruit extracts obtained by maceration using ethanol and acetone. Out of eighteen different compounds registered in the extracts, fifteen were identified by ultra-high-performance liquid chromatography-tandem mass spectrometry. Pomiferin and osajin were characteristic and representative compounds in both ethanolic and acetone extracts of the Osage orange fruit. Both extracts showed good antioxidant activity (EC50 = 0.03 mg/cm3) after 20 min of incubation. The topical administration safety of the extracts was evaluated in vivo by measuring skin biophysical parameters: electrical capacitance and erythema index, as indicators of stratum corneum hydration and irritation, respectively. Based on the results of the in vivo skin tests, it can be concluded that both of the Osage orange fruit extracts are safe for topical administration - they increased skin hydration and reduced skin irritation under the occlusion.

This work aimed to isolate the essential oil from the nutmeg (Myristica fragrans Houtt.) seed, to determine the qualitative and quantitative chemical composition of the obtained essential oil, as w...

Essential oil from rosemary (Rosmarinus officinalis L.) leaves was isolated by conventional hydrodistillation using hydromodulus of 1/15 m/v and by distillation after the plant material pretreatment with 10% v/v aqueous solution of natural deep eutectic solvent glyceline. Qualitative and quantitative composition of the oil was determined by GC/MS and GC/FID analyses, while its antioxidant activity was investigated by DPPH assay. The yield of the essential oil was higher after the pretreatment of the leaves. The distillation method affected the quantitative composition of essential oil, but not its qualitative composition. The essential oil from the pretreated leaves had a higher content of camphor, verbenone and borneol (33.3%, 12.2% and 8.3%, respectively) and better antioxidant activity than the oil obtained by classical hydrodistillation. The advantage of the pretreatment method is the effective improvement of the extraction efficiency of rosemary essential oil from rosemary leaves.

Biodegradable polyurethanes can be the basis for drug delivery systems that are sensitive to external changes. pH-sensitive polyurethanes (PUs) have been used successfully as intravaginal rings and specific drug delivery systems for the colon. In this study, a series of pH-sensitive polyurethane hydrogels with a change of the polyol component (poly(ethylene glycol) 400/poly(propylene glycol) 2000/poly(ethylene glycol)-block-poly(propylene glycol)-block-poly(ethylene glycol) 1100), saccharides as crosslinkers (melibiose/raffinose/starch) and a-hydroxy carboxylic acids as chain extenders (dimethylol propionic acid/lactic acid) were synthesized. Structural characterization of the synthesized polyurethane hydrogels was performed using Fourier transform infrared spectroscopy (FTIR), which showed that the polyurethane synthesis reaction was achieved with successful crosslinking with saccharides and, despite the change of starting components, FTIR spectra for all investigated samples are almost identical. The degree of swelling of the hydrogels was monitored at 25 °C in solutions of pH values 4.5 and 7.4. In samples with the polyol component block1100, the degree of swelling at pH 7.4 (16.09%) was up to 9 times higher than at pH 4.5 (1.82%). The effects of variable parameters on the thermal properties and phase transitions of PUs hydrogels were investigated by thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC). The results showed that by varying the saccharide as a crosslinker, the acid chain extender and the chain length of the polyols, the stated properties of polyurethane hydrogels as potential drug delivery carriers can be influenced.

Benzoic acid has a wide use primarily in food but it is also used in cosmetic, pharmaceutical and other products. Because of noted carcinogenic and toxic characteristics under certain concentration it is considered a pollutant that becomes an important environmental problem. In this study, commercial activated charcoal was tested for the removal of benzoic acid from aqueous solutions. Removal of benzoic acid was investigated in a batch and column system under various values of pH, temperature, activated charcoal granulation and mass. The analysis of all samples was performed by visible absorption spectrometry. The optimum conditions for benzoic acid removal in a batch system were found to be pH 3, contact time of 60 min, the temperature of 273.65 K and adsorbent dose of 10 g L-1. The benzoic acid removal can be performed in a column system as well in which the highest quantity of benzoic acid is removed during the first 20 min (70%) and saturation occurs after 70 min. The used benzoic acid removing methods can be characterized as simple, economical and fast and requiring no chemical treatment.

The quality of the essential oil obtained from the wood verdure of fir from the territory of the Republic of Srpska was analyzed by examining the chemical composition, antioxidant activity and antimicrobial activity of the samples produced by the process of hydrodistillation in industrial production conditions. Two samples of fir essential oil were tested, depending on how long the plant material stood before the hydrodistillation process. The chemical composition of the essential oil was analyzed using GC/MS and GC/FID analysis. The antioxidant and antimicrobial activity of fir essential oil has been examined for its possible application as a natural antioxidant and antimicrobial agent. The obtained results prove the presence of 50 components in the first analyzed sample and 44 components in the second analyzed sample. The total components present (98.3% and 98.7%) were identified. The most common are monoterpene hydrocarbons, followed by sesquiterpene hydrocarbons and oxygen-containing monoterpenes. The antioxidant activity was investigated by the DPPH assay. Fir essential oil has shown the best antioxidant properties after 120 minutes of incubation with an EC50 value of 32.0 ± 0.03 mg/ml and 29.93 ± 0.08 mg/ml. Antimicrobial activity was investigated using a disk diffusion method. The results showed large zones of inhibition for both tested oil samples and for all eight bacterial strains analyzed (from 14.33 ± 0.58 mm to 16.67 ± 1.15 mm) as well as for the fungal strain. The chemical composition, antioxidant and antimicrobial action of fir essential oil obtained from plant material from the Republic of Srpska indicate significant phytomedicine potency.

In this study, the composition and the antioxidant and antimicrobial activity of free and bound phenolics from Urtica dioica L. seeds were studied. The composition of phenolics was determined by isocratic and gradient HPLC methods, and the antioxidant activity by determining DPPH scavenging capacity, reducing the power and FRAP value. The antimicrobial activity was tested by using the discdiffusion method. The content of free phenolics was higher (6000.71 µg gallic acid equivalent per g dry seeds mass) than the content of bound phenolics (2801.16 µg g-1). The extract of free phenolics had a higher FRAP value than the bound, while the bound phenolics had a better DPPH scavenging capacity and the reducing power. Eighteen phenolics have been detected in the free phenolic extract, among which kaempferol 3-O-rutinoside-7-O-rhamnoside was the most abundant (428.55 µg g-1), while ten phenolics have been detected in the bound phenolic extract, among which monocaffeoyl-meso-tartaric acid (406.83 µg g-1) was the most abundant. Both of the extracts have shown a good inhibitory effect on Bacillus cereus ATCC 11778 and Klebsiella pneumoniae ATTC 700603. The study showed that nettle seeds are a good source of natural antioxidants and antimicrobials for potential use in the food and pharmaceutical industry.

Copolymeric hydrogels of poly(N-isopropylmethacrylamide-co-N-isopropylacrylamide), p(NIPMAM/NIPAM), are synthesized by radical polymerization of N-isopropylmethacryl-amide (NIPMAM) and N-isopropylacrylamide (NIPAM) monomers by using the cross-linker ethylen glycol dimethacrylate (EGDM). The synthesized copolymeric p(NIPMAM/NIPAM) hydrogels, starting monomers and the cross-linker were structurally characterized by using Fourier transform infrared spectroscopy (FTIR). The amounts of residual reactants in the synthesized hydrogels were determined by high-pressure liquid chromatography (HPLC). Swelling of p(NIPMAM/NIPAM) hydrogels was investigated in relation to the temperature and pH value of the solution. The obtained values of residual monomer quantities are within acceptable limits and in the range from 2.69 to 5.25 mg g-1 for NIPMAM and 14.55 to 30.80 mg g-1 for NIPAM. The synthesized p(NIPMAM/NIPAM) hydrogels are negatively thermosensitive. The most common mechanisms of transport of a swelling solution in p(NIPMAM/NIPAM) hydrogels are polymer chain relaxation, (Case III), and the anomalous type of diffusion (non-Fickian diffusion). The maximal equilibrium swelling degree of 51.19 was reached by the p(NIPMAM/NIPAM) hydrogel with 1.5 mol% of EGDM at the temperature of 25?C and pH 4, whereas the lowest one of 0.98 was exhibited by the hydrogel with 3 mol% of EGDM at the temperature of 80?C and pH 7. Due to their low content of residual reactants and a satisfactory degree of swelling at various pH values, synthesized p(NIPMAM/NIPAM) hydrogels can be applied as carriers for the controlled release of pharmaceutically active substances.

Waste materials are receiving more attention as concerns about the future of our planet increase. Cellulose is the most common substance in agricultural waste. Agricultural wastes containing cellulose are misplaced resources that could be reused in various fields for both environmental and economic benefits. In this work, 32 different kinds of waste are investigated for chemical modification in order to obtain carboxymethyl cellulose for the production of a superabsorbent hydrogel that can be applied in agriculture. A brief literature review is provided to help researchers wishing to obtain carboxymethyl cellulose by carboxymethylation starting with waste materials. We also provide details about methods to obtain as well as verify carboxymethylation. Carboxymethyl cellulose (CMC), as a constituent of cellulosic water and superabsorbent hydrogels with applications in agriculture, is described. Superabsorbent hydrogels with CMC are able to absorb huge amounts of water and are biodegradable.

The content of free and bound phenolics and their antioxidant capacity in cookies enriched by nettle seed flour and a nettle seed phenolic extract, before, during and after thermal processing (baking at 180°C for 25 min) were examined. The results compare these properties to a cookie obtained only from wheat flour, as the control. Better results were obtained by incorporating nettle seed flour than nettle seed extract. During thermal processing, different changes of phenolic content and antioxidant capacity (increase, decrease or retention) occurred, depending on the form of the phenolics (free or bound), thermal processing time, the cookie and applied antioxidant assays. The free and bound phenolics in the cookie with seed flour were more stable than in the other cookies. At the end of the thermal processing, the cookie with nettle seed flour had a higher content of free and bound phenolics (2.1 and 2.5 times, respectively), and greater antioxidant capacity (the DPPH RSC of free and bound phenolics 9.2 and 4.6 times, and of reducing power 1.6 and 3.4 times, respectively) than the control. There are great possibilities of using nettle seeds in the food industry with the aim of obtaining a functional product with powerful health benefits.

The purpose of the present study was to determine chemical composition and antioxidant activity of commercial peppermint (Aetheroleum menthae piperitae) and basil (Aetheroleum basilici) essential o...

The essential oil from birch (Betula pendula Roth.) buds was obtained by Clevenger-type hydrodistillation. Its qualitative and quantitative composition was determined by gas chromatography in combination with mass spectrometry (GC/MS) and flame ionization detection (GC/FID), respectively. Twenty-seven compounds, mainly sesquiterpene hydrocarbons (78.7%) and oxygenated sesquiterpenes (14.8%), were identified comprising 93.5% of total identified components in the essential oil. The most abundant compounds were germacrene D (21.7%) and -cadinene (17.0%). Antimicrobial activity of isolated essential oil against Gram-positive and Gram-negative bacteria as well as fungus Candida albicans was determined using the disc-diffusion method. The isolated essential oil has shown antimicrobial activity against the following microorganisms: Proteus vulgaris, Bacillus luteus and Klebsiella pneumoniae. Antioxidative activity of the essential oil was determined using the DPPH assay, after adding DPPH radical and after 20min, 30min and 60min incubation with radical. Essential oil showed antioxidant activity.

Restoring the morpho-functional capacity of destroyed and compensations of lost teeth present a challenge for the synthesis of new more effective materials and the improvement of those already on the market. The aim of the manuscript was to present the advantages and disadvantages of contemporary acrylic polymers, dental ceramics, and composites, based on literature data and published research results. The choice of the adequate material is crucial for making not only dental but any product. The synthesis of new materials and the development of new technological procedures have accelerated the advancement of dentistry. Therefore, today's dental compensations faithfully imitate natural teeth and can fully perform their intended function.

This paper presents reduction of ZnO in EPDM formulations and its influence on efficiency of cable isolation by measuring cure behavior, electrical and mechanical properties before and after ageing. These experiments were performed on EPDM formulations by changing three key variables in formulation (concentration of ZnO, type of peroxide and content of ethylene in EPDM). The rheological characterization showed that replacing ZnO in EPDM with proper ethylene content (75 %) with the lower content of ZnO (5 phr) in the recipes, resulted in lower cure time and higher scorch time and higher crosslinking density, which was further supported by Fourier transform infrared spectroscopy (FTIR). Mechanical properties before aging (elongation at break, tensile strength, and hardness) are greater with smaller content of ZnO. The value of percentage change of the properties after aging at 135 °C for 7 days, indicates that recipe D (Perkadox 14/40 (Di (tert-butyl peroxy isopropyl) benzene (DTBPIB)) peroxide cured EPDM has the best performance at tensile strength, and elongation at break. What is more, recipe D, containing 5 phr of ZnO exhibits the desired electrical performance. The paper provides sufficient experimental background to indentify the key physical aspects associated with each of the instabilities that occur at higher amounts of ZnO in formulation, and this in turns provides insight into different occurrences of each instability and how they can be minimized by reduction of ZnO in EPDM mixture.

In this study, poly(N-isopropylacrylamide-co-2-hydroxypropyl methacrylate) hydrogels were synthesized using free radical initiated copolymerization method. Four hydrogels with different cross-linker concentrations were prepared. Semi-crystalline, cross-linked copolymer networks were confirmed by FTIR, SEM and XRD analysis. Variation of swelling behaviour was monitored gravimetrically and thermo-responsiveness has been noticed. An application of synthesized thermo-responsive hydrogels as carriers for the modulated release of anti-inflammatory model drug was investigated. Moreover, naproxen loading into these hydrogels was also determined using FTIR, SEM and XRD techniques and release was analyzed using HPLC method at simulated physiological conditions. Swelling kinetic and mechanism of water transport, as well as diffusion of naproxen through the hydrogels were analyzed. Thus, the aim of this work was to study various compositions of obtained hydrogels and their possibility of application as a thermo-responsive carrier for prolonged naproxen release in order to evaluate as a potential candidate for drug carrier in future pharmaceutical applications.

Poly(N-isopropylmethacrylamide) (p(NiPMAm)) is one of the lesser known homopolymers that has significant potential for designing new &ldquo, intelligent&rdquo, materials. The aims of this work were the synthesis a series of cross-linked p(NiPMAm) hydrogels by the free radical polymerization method and the application of gamma-ray radiation for additional cross-linking. The synthesized p(NiPMAm) hydrogels were structurally characterized by Fourier transform infrared spectroscopy (FTIR) and scanning electron microscopy (SEM). The amount of unreacted monomers was analyzed using high pressure liquid chromatography (HPLC) to evaluate conversion of monomers into polymers. The swelling behavior was monitored in dependence of pH and temperature changes. The previous aim of gamma-ray radiation was the further the cross-linkage of the obtained hydrogel sample in the gelatinous, paste-like state, but the gamma-ray radiation caused decomposition. After absorbing irradiation doses, they transformed into the liquid phase. The results obtained by the gel permeation chromatography (GPC) method indicated that only oligomers and monomers were present in the irradiated liquid material, without molecules with a higher average molar mass, i.e., that the decomposition of the hydrogels occurred. Additionally, the irradiated liquid material was analyzed using the static headspace gas chromatography mass spectrometry (HSS-GC/MS) and gas chromatography/flame ionization detection (HSS-GC/FID) methods. The presence of unchanged initiator molecule and a dominant amount of four new molecules that were different from homopolymers and the reactant (monomer and cross-linker) were determined.

Poly(N-isopropylmethacrylamide) (p(NiPMAm)) is one of the lesser known homopolymers that has significant potential for designing new “intelligent” materials. The aims of this work were the synthesis a series of cross-linked p(NiPMAm) hydrogels by the free radical polymerization method and the application of gamma-ray radiation for additional cross-linking. The synthesized p(NiPMAm) hydrogels were structurally characterized by Fourier transform infrared spectroscopy (FTIR) and scanning electron microscopy (SEM). The amount of unreacted monomers was analyzed using high pressure liquid chromatography (HPLC) to evaluate conversion of monomers into polymers. The swelling behavior was monitored in dependence of pH and temperature changes. The previous aim of gamma-ray radiation was the further the cross-linkage of the obtained hydrogel sample in the gelatinous, paste-like state, but the gamma-ray radiation caused decomposition. After absorbing irradiation doses, they transformed into the liquid phase. The results obtained by the gel permeation chromatography (GPC) method indicated that only oligomers and monomers were present in the irradiated liquid material, without molecules with a higher average molar mass, i.e., that the decomposition of the hydrogels occurred. Additionally, the irradiated liquid material was analyzed using the static headspace gas chromatography mass spectrometry (HSS-GC/MS) and gas chromatography/flame ionization detection (HSS-GC/FID) methods. The presence of unchanged initiator molecule and a dominant amount of four new molecules that were different from homopolymers and the reactant (monomer and cross-linker) were determined.

The aim of the present study was to determine the content of residual monomer methyl methacrylate (MMA) in cold and hot polymerized poly(methyl methacrylate) (PMMA), both widely applicable in dentistry, by using MHE-GC-MS (multiple headspace extraction analysis by gas chromatography-mass spectrometry) in combination with GC-FID (gas chromatography with flame-ionization detection). The samples of PMMA were obtained by free-radical polymerization of MMA at room temperature (cold polymerized PMMA) and at 100 °C (hot polymerized PMMA), according to the manufacturer’s instructions. The MHE-GC-MS method consisted of ten successive extractions of MMA from the polymerized samples. According to the constructed calibration curve, the content of residual MMA in PMMA samples (mgMMA/gPMMA) was determined. Intramuscular implantation of sample materials was performed in experimental animals (rats) in order to demonstrate potential adverse effects of the unpolymerized residual reactants to the tissue in direct contact with polymeric implants. The content of residual monomer in cold polymerized PMMA was higher (15.75 mgMMA/gPMMA) in comparison to hot polymerized PMMA (10.96 mgMMA/gPMMA). The implanted samples of cold-polymerized acrylic resin showed intense inflammatory response of the surrounding tissue. According to the obtained results, hot polymerized PMMA is safer for use in dentistry.

The aim of this study was to isolate the essential oil from ripe and disintegrated caraway fruit by Clevenger-type hydrodistillation, to determine its qualitative and quantitative composition and to examine its antioxidant activity, as well as to determine the qualitative and quantitative chemical composition of the caraway volatile compounds extracted by HS-SPME technique. The essential oil from disintegrated caraway fruit was obtained by Clevenger-type hydrodistillation with hydromodulus 1:10 m/V during 180 minutes. Volatile compounds from caraway fruit were extracted by headspace-solid phase microextraction (HS-SPME) using 75 mm fiber coated with Carboxen®/Polydimethylsiloxane (PDMS). The qualitative and quantitative composition of the essential oil and volatile compounds was determined by gas chromatography coupled with mass spectrometry (GC-MS) and flame ionization detection (GC-FID). Twenty-seven different compounds were separated and identified in the essential oil. Twenty-six compounds were identified in the volatiles extracted by HS-SPME. The most abundant compounds in both examined samples were limonene and carvone. The content of carvone in the essential oil was 72%, while the limonene content was 25.6%. In the volatiles obtained by HS-SPME, the limonene was present with 72.1% and carvone with 24.6%. The difference in the chemical composition is due to the oxidation of limonene to carvone during the hydrodistillation. The antioxidative activity of the caraway essential oil was determined by using DPPH assay immediately after adding DPPH radical and after 20 and 40 min of incubation with the radical. The caraway fruit essential oil showed a satisfactory antioxidant activity. The oil incubated for 40 min (EC50=4.6 mg/cm³) showed the best antioxidant activity.

The temperature- and pH-sensitive poly(N-isopropylacrylamide-co-acrylic acid) hydrogels, poly(NIPAM-co-AA), were synthesized by radical polymerization. The characterizations of hydrogels based on N-isopropylacrylamide (NIPAM) and acrylic acid (AA) before and after adsorption of heavy metal ions was performed by Fourier transform infrared spectroscopy and scanning electron microscopy. Heavy metal ions (Cr, Mn, Pb) adsorbed onto poly(NIPAM-co-AA) hydrogels were identified using the energy-dispersive X-ray spectroscopy. The mechanism of the water transport within the matrix of synthesized poly(NIPAM-co-AA) hydrogels at pH 4.5 is Super Case II diffusion, and at pH 6.8 corresponds to the non-Fickian diffusion mechanism. The effect of pH, temperature, contact time, and the initial concentration of heavy metals on the adsorption process of Cr(VI), Mn(II), and Pb(II) ions from aqueous solutions onto poly(NIPAM-co-AA) hydrogels were investigated. The kinetic and equilibrium data were best fitted by the pseudo-second-order model and Langmuir adsorption isotherm. Thermodynamic results indicate that the removal process of heavy metal ions from aqueous solutions by poly(NIPAM-co-AA) hydrogels was spontaneous and exothermic in nature. Maximum adsorption capacities of poly(NIPAM-co-AA) hydrogels for heavy metal ions decrease in the following order: Pb(II) > Cr(VI) > Mn(II). This is a post-peer-review, pre-copyedit version of an article published in Polymer Bulletin. The final authenticated version is available online at: [http://dx.doi.org/10.1007/s00289-018-2295-0]

Acrylic restorations in the mouth are exposed to strong occlusal forces. Their mechanical properties depend on the type and method of their polymerization. The aim of this study is a comparative analysis of mechanical properties (flexural strength and modulus of elasticity) of acrylic materials before and after the post-polymerization treatments (water boiling, microwave irradiation and water storage). The study included denture base resins, as well as an acrylate for orthodontic appliances impregnated with aesthetic beads. Flexural strength, modulus of elasticity and the deflection were measured immediately after polymerization, after a hot and microwave post-polymerization and after immersion in a water bath at the temperature of 37?C. The applied post-polymerization methods resulted in an increase in flexural strength and modulus of elasticity relative to the initial values for all tested materials. Being aware of the reduction in fracture risk of dental prosthesis after a proposed post-polymerization procedure, it could be used in all clinical situations where there is an increased risk of damage to dentures.

The main goal of this study was to develop a liposome formulation with sulfanilamide and to investigate the liposomes impact on its release and stability to the UV-A/UV-B and UV-C irradiation. Liposome dispersions with incorporated sulfanilamide were prepared by thin-film hydration method and liposomes role to the sulfanilamide release was investigated by using a dialysis method. Comparatively, sulfanilamide in phosphate buffer solution was subject to release study as well to the UV irradiation providing for the possibilities of kinetics analysis. In vitro drug release study demonstrated that 20% of sulfanilamide was released from liposomes within 1 h that is approximately twice as slower as in the case of dissolved sulfanilamide in phosphate buffer solution. The kinetic release process can be described by Korsmeyer–Peppas model and according to the value of diffusion release exponent it can be concluded that drug release mechanism is based on the phenomenon of diffusion. The sulfanilamide degradation in phosphate buffer solution and liposomes is related to the formation of UV-induced degradation products that are identified by UHPLC/MS analysis as: sulfanilic acid, aniline and benzidine. The UV-induced sulfanilamide degradation in the phosphate buffer solution and liposome vesicles fits the first- order kinetic model. The degradation rate constants are dependent on the involved UV photons energy input as well as sulfanilamide microenvironment. Liposome microenvironment provides better irradiation sulfanilamide stability. The obtained results suggest that liposomes might be promising carriers for delayed sulfanilamide delivery and may serve as a basis for further research. Keywords: Sulfanilamide, Liposomes, Stability, Irradiation, Degradation, Release

Novel biobased poly(ester-urethane)s (PUDs) were synthesized by solvent free homogeneous solution polymerization of poly(caprolactone) diol (PCL), castor oil-based polyols (COLs), dimethylolpropionic acid (DMPA), isophorone diisocyanate (IPDI) and 1,4-butane diol (BD) as the chain extender. The polyurethane dispersions were prepared by adding required amount of triethylamine (TEA) and water. In this Work, castor oil-based polyols have been synthesized using the depolymerized oligoester obtained from glycolysis of PET waste with poly(ethylene glycol) (PEG 400) and castor oil. The effects of the soft segments content on the thermal and coatings properties of resulting polyurethane films have been examined by Fourier transform infrared spectroscopy (FTIR), differential scanning calorimetry (DSC), thermogravimetric analysis (TGA) and measurement of the coatings properties. Phase separation of polyurethane shows a strong correlation with crystallization behaviour of the polyurethane prepared. It is established that all PUD samples containing PCL as a part soft segment with different molar ratio of castor-oil polyol are crystallisable polymers. The results from XRD analysis have showed that highest degree of crystallinity (23 and 22%) is reached in polyurethanes based on the largest content PCL diol (CPU77 and CPU73). The thermal stability of samples based on (COL/PCL molar ratio 0.25:0.75) possesses the best thermal properties but less values hardness coatings which can be ascribed to a decrease of the hard segment i.e. DMPA content in polyurethane dispersions. The long-term stability of polyurethane dispersions has been investigated using UV vis spectroscopy. The physico-mechanical properties such as hardness adhesion test and gloss of the dried films have also been determined considering the effect of soft segment content on coating properties. (C) 2016 Elsevier B.V. All rights reserved.

Dichloromethane soil samples extracts were prepared using Soxhlet extraction technique, and after clean-up step, gas chromatography-mass spectrometry analysis of 16 priority polycyclic aromatic hyd...

Hydrogels are synthesized by the method of radical polymerization of monomers: N-isopropylacrylamide (NIPAM) and acrylic acid (AA). Characterization of poly(N-isopropylacrylamide- co-acrylic acid) hydrogels, p(NIPAM/AA), has been performed by Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD) and by determination of the swelling behaviour in aqueous solutions at different temperatures (25, 31 and 37°C) and pH values (2.2, 4.5, 6 and 6.8). After lyophilisation in the solution at pH 6 and temperature of 25°C, p(NIPAM/AA) hydrogels have rapidly reached equilibrium degree of swelling, αe, in comparison to non-lyophilized samples. The mechanism of solvent transport within matrix in lyophilized samples corresponds to less Fickian diffusion, whereas Super case II diffusion is characteristic for non-lyophilized samples. p(NIPAM/AA) hydrogel with 1.5 mol% of ethylene glycol dimethacrylate (EGDM) at the temperature of 25°C and pH 6.8, has reached the highest swelling equilibrium degree, αe = 259.8. The results of swelling studies have shown that p(NIPAM/AA) hydrogels can be classified as superabsorbent polymers (SAPs). For the evaluation of pH and temperature influences on synthesized hydrogels swelling, a full three-level experimental design has been used. Two-factor interaction model (2FI) is the most optimal model of a full three-level experimental design for representing the swelling equilibrium degree of p(NIPAM/AA) hydrogels as a function of investigated parameters, i.e., temperature and pH. [Project of the Serbian Ministry of Education, Science and Technological Development, Grant no. TR-34012]

Introduction. Porosity and surface adherence of acrylates make them collectors of infectious content from the mouth. This applies particularly to cold-curable acrylates, whose structure is less compact. The aim of this study was to investigate the antimicrobial effects of cold polymerized dental acrylics after impregnation with silver nanoparticles. Material and Methods. Different concentrations (2%, 5% and 10%) of silver nanoparticles were added to the polymer components (powder) of cold polymerizing acrylate, after which disk-shaped samples, 10 mm, in diameter, were made. A disk of silver nanoparticles was used as a control for our study. Antimicrobial activity was investigated using the disc diffusion method on the two most common oral cavity infecting agents - Gram positive bacterium, Staphylococcus aureus ATCC 25923, and fungus Candida albicans ATCC 2091. The results have shown that the control sample as well as the samples of silver impregnated acrylics resins exhibit antibacterial activity. The growth zone inhibition of Staphylococcus aureus in the culture medium is proportional to the concentration of silver nanoparticles in the cold curing acrylic resin. On the other hand, the test samples did not inhibit the growth of Candida albicans in the medium. Conclusion. Silver nanoparticles in cold curing acrylic resin demonstrated antibacterial activity. Expanding their antimicrobial spectrum of activity and their potential clinical application will be the subject of the future research.