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Polyelectrolyte complexes (PECs) are attractive carriers with recognized potential to enhance oral delivery of poorly soluble high-dosed low-molecular-weight drugs. The formulation of solid oral dosage forms requires the drying of PECs, which may affect their physicochemical and biopharmaceutical properties. The aim of this study was to investigate the effect of spraydrying on the properties of ibuprofen-loaded chitosan/xanthan gum PECs and to assess the drug release kinetics from such PECs filled into hard capsules in comparison with corresponding PECs which are dried under ambient conditions. The yield, ibuprofen content, entrapment efficiency, and residual moisture content of spray-dried PECs were lower than those of ambient-dried PECs. Better flowability of spray-dried PECs was attributed to the almost spherical particle shape, shown by scanning electron microscopy. DSC and PXRD analysis confirmed the amorphization of ibuprofen during spray-drying. All the investigated PECs, obtained by drying under ambient conditions as well as by spray-drying, had high rehydration capacity both in 0.1 M hydrochloric acid (pH 1.2) and phosphate buffer pH 7.4. In vitro ibuprofen release from dried PECs was controlled during 12 h with the release of approximately 30% of entrapped ibuprofen. Spray-dried PECs provided better control of ibuprofen diffusion from the carrier compared to the ambientdried ones.

The aim of this work was to investigate a possibility of preparing composite zein/natural resin (shellac and rosin) nanoparticles by antisolvent co–precipitation from their aqueous ethanol solutions. Influence of zein/resin mass ratio (1/0, 0.8/0.2, 0.5/0.5, 0.4/0.6 and 0/1) and pH (2–12) on particle size, d, and zeta potential, , of the prepared particles was studied. The functional properties of zein/rosin composite nanoparticles were evaluated by studying carvacrol encapsulation. It was shown that the antisolvent precipitation can be successfully used to prepare the shellac and rosin nanoparticles, as well as the composite zein/shellac and the zein/rosin nanoparticles. Colloidal properties, d and , of the obtained nanoparticles are influenced by the zein/ /resin mass ratio and the pH of nanoparticles’ dispersions. The isoelectric point of composite nanoparticles can be modulated by varying the zein/resin mass ratio. It was found that the zein/rosin nanoparticles are suitable for carvacrol encapsulation, where carvacrol release is enhanced by increasing the rosin share in the composite zein/rosin nanoparticles. [Project of the Serbian Ministry of Education, Science and Technological Development, Grant no. III 46010/3]

Double emulsions are complex liquid dispersion systems in which the droplets of one dispersed liquid are further dispersed in another liquid, producing W/O/W or O/W/O emulsions. W/O/W emulsions are the most studied systems because they have great potential application. However, despite all the advantages, that these systems offer, it is very difficult to obtain stable formulations, and this is the reason for their limited practical application. The use of biopolymers to stabilize double emulsions could give rise to pharmaceutical and food applications. Based on previous studies, appropriate concentrations of gelatin and sodium caseinate (NaCAS) were selected to investigate the possibility of stabilization of double W/O/W emulsions by this system, if they are present in the outer aqueous phase. The investigations showed that interactions between gelatin and NaCAS in the outer water phase, as well as the composition of the mixtures of lipohilic emulsifiers used for the primary W/O emulsions preparation, influences the droplets size and sedimentation stability of double emulsions. The most stable emulsions were obtained at a NaCAS concentration when an insoluble coacervate forms (0.5 mass %) and at concentrations higher then this, when soluble negatively charged complexes adsorb at the oil/water interface. [Project of the Serbian Ministry of Education, Science and Technological Development, Grant no. III46010]

Chitosan is a cationic biopolymer, which attracts more and more attention in recent years, due to its exceptional physical and chemical properties, expressive biocompatibility and possibilities of obtaining from renewable sources. Formed polymer/surfactant complexes affect changes in the rheological properties and the final result is the formation of coacervates. The purpose of this study was to investigate the rheological properties of aqueous solutions of cationic polyelectrolyte, chitosan and sodium lauryl ether sulfate (SLES), an anionic surfactant, widely used in the cosmetics industry. Using the Thermo Haake RS600 rheometer, changes in the rheological and elastic properties of chitosan and SLES mixtures have been identified, gained as a result of the interaction of the components. In all examined samples coefficient of thixotropy was increasing with increase SLES concentration and achieves a maximum value at the mass ratio chitosan:SLES 1:2, after which it reduces. The oscillatory measurements in mixtures, performed by amplitude sweep method at low oscillating frequency 1 Hz, show that the linear viscoelastic region increases with increasing SLES concentration up to the same chitosan:SLES mass ratio. By monitoring the changes in the rheological parameters of the mixtures over five days, it was observed that the viscosity, the coefficient of thixotropy and elasticity were increasing, indicating that changes in the system occur over a longer period of time. In that manner, obtained results indicate the possibility of using rheological methods for a more detailed description of the interaction in the chitosan/SLES mixtures, important for their application in cosmetics and pharmaceutical industries. [Project of the Serbian Ministry of Education, Science and Technological Development, Grant no. III46010]

Pumpkin (Cucurbita pepo) seed protein hydrolysate (PSPH) was obtained by enzymatic hydrolysis of pumpkin seed protein isolate using pepsin. Influence of pH (3, 5 and 8) and ionic strength, Ic (0–1 mol dm-3), on the adsorption kinetics of PSPH (diffusion rate constant, kdiff, and adsorption rate constant, kads), interfacial pressure (π) and interfacial dilatational properties (dilatational elasticity, E′, and viscosity, E″) of the oil–PSPH solution interfaces was investigated at different PSPH concentrations (c = 0.0014–14 g dm-3). It was found that PSPH adsorbs to the interface at c ˃ 0.0014 g dm-3, regardless of pH and ionic strength, as evidenced by the increase in interfacial pressure. The kdiff and kads value were found to be the highest at pH 3 and the lowest at pH 5 at the corresponding concentrations. The dilatational properties of the interfaces, which were investigated at different oscillation frequencies, ν, 0.01–0.2 Hz, showed that the E′ of the oil–PSPH solution interfaces is much higher than its E″. Moreover, E′ increases with increasing PSPH concentration at pH 5 and 8, and with increasing Ic, regardless of the pH, while E″ changes only minimally. [Project of the Serbian Ministry of Education, Science and Technological Development, Grant no. III 46010]

Water in oil (W/O) emulsions are dispersed systems which have very wide application as a carriers in the food, pharmaceutical and cosmetic industry products. The main problem with practical application of such systems is their low stability. The emulsifiers used to stabilize this type of emulsions are with low hydrophilic-lipophilic balance values. The present work examines the possibility of the application of mixtures of lipophilic emulsifiers polyglycerol polyricinoleate (PGPR) and polyglycerol fatty acid esters for stabilization of W/O emulsions. First of all, the adsorption properties of the used emulsifiers were examined by tensiometic measurements. Based on these results, two emulsifiers PGPR and decaglycerol decaoleate (Caprol 10G10O) were selected for the preparation of the emulsions, as well as their mass ratios and total concentrations. The results of the investigation of the emulsions properties (dispersion analysis and sedimentation stability) showed that more stable emulsions can be obtained by decreasing the Caprol 10G10O mass ratio and increasing the total concentration of emulsifiers.[Project of the Serbian Ministry of Education, Science and Technological Development, Grant no. III46010]

Contemporary formulations of cosmetic and pharmaceutical emulsions may be achieved by using combined polymer/surfactant system, which can form complexes with different structure and physicochemical properties. Such complexation can lead to additional stabilization of the emulsion products. For these reasons, the main goal of this study was to investigate the interfacial properties of chitosan/sodium dodecyl sulfate complexes. In order to understand the stabilization mechanism, the interface of the oil/water systems that contained mixtures of chitosan and sodium dodecyl sulfate, was studied by measuring the interfacial tension. Considering the fact that the properties of the oil phase has influence on the adsorption process, three different types of oil were investigated: medium-chain triglycerides (semi-synthetic oil), paraffin oil (mineral oil) and natural oil obtained from the grape seed. The surface tension measurements at the oil/water interface, for chitosan water solutions, indicate a poor surface activity of this biopolymer. Addition of sodium dodecyl sulfate to chitosan solution causes a significant decrease in the interfacial tension for all investigated oils. The results of this study are important for understanding the influence of polymer-surfactant interactions on the properties of the solution and stability of dispersed systems. [Project of the Serbian Ministry of Education, Science and Technological Development, Grant no. III46010]

Water-in-oil (W/O) emulsions are dispersed systems which are often used in the pharmaceutical, cosmetic and food industries as products, or as carriers of active substances. It is well known that they are very unstable, so that selection of the emulsifier and properties of the oil and water phase are main factors affecting their stability. The aim of this paper was to examine the possibility of application of a lipophilic, polymeric emulsifier, PEG 30-dipolyhydroxystearate (CithrolTM DPHS), for stabilization of W/O emulsions. Behaviour of the emulsifier at W/O interfaces was determined by means of tensiometry. A series of emulsions were prepared with 20% (w/w) of water and different types of oil. Droplet size, droplet size distribution, viscosity, and sedimentation stability during 30 days of storage at room temperature of the emulsions prepared with paraffin oil, olive oil, grape seed oil, and medium-chain triglycerides, stabilized with 1% CithrolTM DPHS, were determined. All investigated emulsions were stable for 30 days, except the one prepared with paraffin oil. The results of this study confirmed that PEG 30-dipolyhydroxylstearate is a good emulsifier and stabilizer of W/O emulsions which contain different types of oil. [Projekat Ministarstva nauke Republike Srbije, br. III46010]

Pumpkin seed protein isolate (PSPI) was enzymatically hydrolysed by pepsin to obtain pumpkin seed protein hydrolysate, PSPH. Investigation on solubility, interfacial and emulsifying properties of both PSPI and PSPH was conducted under different conditions of pH (3-8) and ionic strength (0-1 mol/dm3 NaCl). PSPI had the lowest solubility, i.e. isoelectric point (pI), at pH 5. PSPH had higher solubility than PSPI over whole range of pH and ionic strengths tested. Decrease in surface and interfacial tension evidenced that both PSPI and PSPH adsorb at air/protein solution and oil/protein solution interface. Emulsions (20 % oil in water) stabilized by 1 g/100cm3 PSPI or PSPH solution were prepared at pH 3, 5 and 8 and ionic strength of 0 and 0.5 mol/dm3 NaCl. PSPH stabilized emulsions from coalescence at all pH and ionic strengths tested. PSPI was able to stabilize emulsions at pH 3 and 0 mol/dm3 NaCl, and at pH 8 regardless of ionic strength, while emulsions at pH 5 and both 0 and 0.5 mol/dm3 NaCl and at pH 3 when ionic strength was increased separated to oil and serum layer immediately after preparation. All emulsions were susceptible to creaming instability. [Projekat Ministarstva nauke Republike Srbije, br. III 46010]

Polymer/surfactant association is a cooperative phenomenon where surfactant binds to the polymer in the form of aggregates, usually through electrostatic or hydrophobic forces. As already known, polyelectrolytes may interact with oppositely charged surfactants through electrostatic attraction that results in polymer/surfactant complex formation. This behavior could be desirable in wide range of application of polymer/surfactant mixtures, such as improving colloid stability, gelling, emulsification and microencapsulation. In the present study surface tension, turbidity, viscosity and electrophoretic mobility measurements were used to investigate interactions of cationic polyelectrolyte chitosan (Ch) and oppositely charged anionic surfactant, sodium dodecyl sulfate (SDS), in buffered water. Obtained results show the presence of interactions that lead to Ch/SDS complexes formation at all investigated pH and for all investigated polymer concentrations. Mechanisms of interaction, as well as characteristics of formed Ch/SDS complexes, are highly dependent on their mass ratio in the mixtures, while pH has no significant influence. [Projekat Ministarstva nauke Republike Srbije, br. II46010]

Mixtures of polymers and surfactants are commonly found in a range of products of pharmaceutical, cosmetic, and food industry. Interaction between polymers and surfactants influences different properties of these products, e.g. stability, flow properties, phase behavior, etc. It is known from previous work that an interaction in binary mixtures of hydroxypropylmethyl cellulose (HPMC) and sodium dodecylsulfate (SDS) takes place when SDS concentration (CSDS.) is higher than the critical association concentration (CAC) and lower than the polymer saturation point (PSP). The interaction results in the formation of an HPMC-SDS complex. The objective of this work was to study the effect of the ionic strength on the HPMC-SDS complex formation by rheological investigation. The HPMC/SDS mixtures composed of 0.70 % wt. HPMC, and 0.00 % to 2.50 % wt. SDS were prepared in deionized water, 0.01M and 0.05M NaCl solution. It was found that an increase in the ionic strength influences the HPMC-SDS complex formation by increasing the zero shear viscosity of the mixtures in the interaction region (CACPSP. The HPMC/SDS mixtures showed a shear thinning or a shear thickening flow properties depending on CSDS. The flow properties were influenced by the ionic strength of the mixtures.[Projekat Ministarstva nauke Republike Srbije, br. III46010]

Rheological properties of mixtures of hydroxypropylmethyl cellulose (HPMC), a nonionic associative cellulose ether, and sodium dodecylsulfate (SDS), an anionic surfactant, were investigated by viscosity measurements performed at different shear rates (0.1-6000 s-1). HPMC/SDS mixtures containing different concentrations of SDS (CSDS=0.00-3.50 % w/w) and HPMC concentrations which corresponded to the overlap parameter c/c*=3, 6, and 12 were prepared. All HPMC/SDS mixtures were found to be shear-thinning when examined in a low-end-to mid-range of the applied shear rates. The degree of shear-thinning, n, and viscosity of the mixtures were influenced by composition of HPMC/SDS mixtures and HPMC-SDS complex formation. The changes in n ranged from values typical for highly shear thinning to almost perfectly Newtonian liquids, and were more pronounced as c/c* was increased from 3 to 6 and 12. A change in flow profile and a buildup of the first normal stress difference (N1) was observed in HPMC/SDS mixtures with c/c*=6 and 12 and CSDS 0.55-1.00 % and 0.55-2.50 %, respectively, when a critical shear rate, crit. was exceeded, suggesting that a shear-induced structure formation in the mixtures took place. [Projekat Ministartsva nauke Republike Srbije, br. Grant III 46010]

Surfactant mixtures are very often used in various cosmetic and pharmaceutical products because they commonly act in synergism and provide more favorable properties than the single surfactants. At the same time, the 9 presence of polymers in mixtures of surfactants may lead to molecular interactions thereby affecting product stability and activity. For these reasons it is very important to determine the surfactant interactions influence on 1micellization and mixed micellization, as well as polymer-surfactants mixed micelles interactions. In this work we examined self-aggregation of nonionic surfactants, polysorbate 20 (Tween 20), polyoxyethylene octylphenyl ether (Triton X100) and polyoxyethylene-polyoxypropylene block copolymer (Pluronic F68) with ionic surfactant, sodium dodecylsulfate, in aqueous solution at 40ºC using conductometric titration method. It was found that concentration region for mixed micelle formation depends on nonionic surfactant characteristics and its concentration. Formation of surfactants mixed micelles in the presence of nonionic polymer, hydroxypropylmethyl cellulose, and their binding to polymer hydrophobic sites, were investigated too. Analysis of obtained results points to different kinds of interactions in investigated systems, which are crucial for their application. [Projekat Ministarstva nauke Republike Srbije, br. III 46010]

Numerous species of the genus Streptomyces, on the appropriate cultivation medium in the process of submerged biosynthesis, as a product of the secondary metabolism, and under aerobic conditions synthesize pharmacologically active compounds. The aim of presented study was optimization of different nitrogen sources in the cultivation medium for the production of antimycotics using a strain of Streptomyces spp. isolated from the environment. Experiments were carried out in accordance with Box-Behnken design with three factors at three levels (peptone: 3.0 g/l, 7.0 g/l and 11.0 g/l; yeast extract: 1.0 g/l, 3.0 g/l and 5.0 g/l; soybean meal: 5.0 g/l, 15.0 g/l and 25.0 g/l) and three repetitions in the central point. Cultivation mediums were analyzed for determination of residual sugar, residual nitrogen, pellet diameter and RNA. Also, antimycotic activity of the obtained culti­vation mediums was determined using diffusion disc method on the Aspergillus spp. as the test microorganism. For the optimization of selected parameters, a Response Surface Methodology was used and the obtained data were analyzed using the software package DESIGN EXPERT 8.1. Achieved model with a coefficient of determination (R) of 0.952 predicted that the maximum inhibition zone diameter (24.0 mm) against microorganism Aspergillus spp. and the minimum amount of residual sugar (0.551528 g/l) under applied experimental conditions was produced when the contents of varied nitrogen sources were: peptone 11.0 g/l, yeast extract 4.32 g/l and soybean meal 25.00 g/l.

Rheology modifiers are common constituents of food, cosmetic and pharmaceutic products. Often, by using two or more of them, better control of the product rheological properties can be achieved. In this work, rheological properties of hydroxypropymethyl cellulose (HPMC) and sodium carboxymethyl cellulose (NaCMC) solutions of different concentrations were investigated and compared to the flow properties of 1% HPMC/NaCMC binary mixtures at various HPMC/NaCMC mass ratios. Solutions of HPMC and NaCMC were found to be pseudoplastic, where pseudoplasticity increases with increase in the macromolecules concentration. Changes of the degree of pseudoplasticity, n as well as the coefficient of consistency, K with the concentration are more pronounced in HPMC solutions when compared to the NaCMC ones. This is mostly due to the ability of HPMC molecules to associate with each other at concentrations above critical overlap concentration, c , and greater flexibility of macromolecular chains. Binary mixtures of HPMC/NaCMC were also found to be pseudoplastic. Experimentally obtained viscosities of the mixture were proved to be larger than theoretically expected ones, indicating viscosity synergism as a consequence of HPMC-NaCMC interaction. Maximum in synergy was observed when HPMC/NaCMC mass ratio was 0.4/0.6, no matter of the shear rate applied. On the other hand, it was found that relative positive deviation, RPD decreases when shear rate is increased.

Background/Aim. Elevation in adduction is the most common pattern of vertical strabismus, and it is mostly treated with surgery. The results of weaking of inferior oblique muscle are very changeable. The aim of this study was to evaluate binocular vision using sensory tests before and one and six months after the surgery. Methods. A total of 79 children were divided in two groups: the first, with inferior oblique muscle of overaction (n = 52), and the second with dissociated vertical deviation (DVD), and primary inferior oblique muscle overaction (n = 27). We tested them by polaroid mirror test (PMT), Worth test at distance and near, fusion amplitudes on sinoptofore, Lang I stereo test and Wirt-Titmus stereo test. We examined our patients before and two times after the surgery for vertical strabismus. Results. Foveal suppression in the group I was found in 60.5% of the patients before, and in 56.4% after the surgery. In group II Foveal suppression was detected in 64.7% of the patients before, but in 55.6% 6 months after the surgery with PMT. Worth test revealed suppression in 23.5% of the patients before, and in 40.7% after the vertical muscle surgery. Parafoveal fussion persisted in about 1/3 of the patients before the surgery, and their amplitudes were a little larger after the surgery in the group I patients. Lang I stereo test was negative in 53.9% before and 51.9% after the surgery in the group I, and in 48.2% of the patients before and after the surgery in the group II patients. Wirt-Titmus stereo test was negative in 74.5% of the patients before and in 72.9% after the surgery in the group I, but in the group II it was negative in 70.8% before and in 68.0% of the patients 6 months after the surgery. Conclusion. Binocular responses were found after surgery in 65.7% of the patients the group I and in 55.6% patients the group II. There was no significant difference between these two groups, but binocular responses were more often in the patients of the group I.

Essential oil content (0.05 %) of marigold (Calendula officinalis L.) was determined using the official steam distillation procedure. High-pressure CO2 extraction of plant material under supercritial (100, 200 and 300 bar and 40°C) and subcritical (60, 90 and 120 bar and 15°C) conditions for 3 h was investigated. It was found that the increase in the pressure promoted an increase in the yield. The essential oil contents obtained from the investigated CO2 extracts by steam distillation were significantly higher (1.52-2.70 times) and increased with pressure. Major constituents of the oil, identified using GC-MS and GC-FID, were α-cadinol (26.54 %), T-cadinol and T-muurolol (9.80 %), γ-cadinene (2.99 %), hexadecanoic acid (2.95 %), and ledane (2.45 %). In addition, the essential oils of the CO2 extracts contained δ-cadinene (6.50-19.87 % under supercritical and 16.09-19.41 % under subcritical conditions), which was not found in the essential oil obtained from the plant by steam distillation. The extraction kinetics was investigated at 200 bar and 40 °C. The total extract obtained after 10 h of extraction was 6.54 % and essential oil content in it, refering to plant material, was 0.209 %, which is 4.16 time more than the one determined by the standard steam distillation procedure.

Background. The accumulation of risk factors for central retinal artery occlusion can be seen in a single person and might be explained by the metabolic syndrome. Case report. We presented the case of a 52-year-old man with no light perception in his right eye. The visual loss was monocular and painless, fundoscopy showed central retinal artery occlusion and the laboratory investigation showed the raised erythrocyte sedimentation rate of 105 mm/h and the raised C-reactive protein of 22 mg/l. Specific laboratory investigations and fluorescein angiography excluded the presence of vasculitis, collagen vascular diseases, hypercoagulable state and antiphospholipid syndrome. Conclusion. The patient met all the five of the National Cholesterol Education Program (NCEP) criteria for the metabolic syndrome: hypertension, abnormal lipid profile, abnormal glucose metabolism, obesity and hyperuricemia. Measurement of C-reactive protein is useful for the assessment of therapeutic systemic effect on any abnormality in the metabolic syndrome. Individual therapy for all risk factors in the metabolic syndrome is necessary to prevent complications such as cardiovascular, retinal vascular diseases and stroke.

Background. Radiation retinopathy is vasculopathy induced by ionising radiation delivered by either brachytherapy or teletherapy for ocular and nonocular malignancies. The first signs of radiation retinopathy typically occur a few months to a few years after the exposure to ionizing radiation. Case report. In the 3 of our patients, changes like capillary telangiectasia, microaneurysms, intraretinal hemorrhages, hard exudation, and capillary nonperfusion showed a clinical picture of macular edema. Two of the patients were suspected of diabetic retinopathy, and 1 patient had optic neuropathy. In our group of patients a latent period was between 3 and 8 years. The incidence of radiation retinopathy increases significantly with the total doses of radiation above 45 Gy, and, thus, it has not been found in the lower doses. Conclusion. Radiation retinopathy is a diagnostical and therapentical problem. Clinical picture can be identical to that of diabetic retinopathy suggesting a common pathophysiologic mechanism of the damage to capillary endothelial cells, and the importance of clinical examination, anamnesis and fluorescein angiography.

Many food, pharmaceutical, cosmetic and chemical products exist in the form of emulsions. A common problem with emulsions is their instability. One method of effective protection against coalescence of the particles is to raise the viscosity and lower surface tension by adding a polymer and low-molar-mass surfactant. Interaction between polymer and surfactant could change the adsorption layer around the oil droplets in emulsion which effects emulsion stability. In this paper, the influence of low-molar-mass anionic surfactant, sodium dodecylsulfate (SDS), on the properties of hydroxypropylmethyl cellulose (HPMC) stabilized emulsion, has been investigated. Changes of viscosity and rheological properties of emulsion caused by the HPMC-SDS interaction in continuous phase were measured and stability of emulsions was observed during two months of storage. Significant increase in viscosity and stability of the emulsions was found at SDS concentrations leading to HPMC-SDS interaction in the continuous phase. Stability of emulsions changed with time and was influenced by the HPMC-SDS interaction.

Interactions between the polymers and surfactants in solution have widely been investigated because of their scientific and technological importance. These interactions can be utilized to modify the physicochemical properties of system in many food products, pharmaceutical formulations, personal care products, paints, pesticides, etc. Interaction between nonionic polymer - hydroxypropylmethyl cellulose (HPMC) and anionic surfactant - sodium laurylsulfate (SDS) in solution has been investigated in this paper by rheological measurements. Rheological measurements are performed by rotational viscometer at 20°C and changes of rheological characteristics of HPMC solutions (0.5-1.5%) with increasing SDS concentrations (0-4.0%) were determined. The results of these investigations showed that viscosity of the solution is dependant on HPMC-SDS interaction. At particular SDS concentration viscosity increases, reach maximum and after that decreases until reach constant value. From the viscosity changes the characteristic concentrations of SDS, critical aggregation concentration (cac) and polymer saturation point (psp), were determined. These concentrations are in linear relationships with HPMC concentrations. Rheological properties of the solution are strong influenced by HPMC-SDS interaction and exhibits more or less pronounced pseudoplastic behavior, which changes to Newtonian one after the psp has been reached.

One of the most significant aspects of polymer-surfactant interaction, from the practical point of view, is that of rheology control and viscosity enhancement. In the oppositely charged polyelectrolyte-surfactant system strong ionic interaction often leads to precipitation of the formed complex yielding serious problems. In this paper the interaction between anionic polyelectrolyte - sodium carboxymethylcellulose (NaCMC) and cationic surfactant - cethyltrimethylammonium bromide (CTMAB) has been investigated by rheological measurements. Addition of electrolyte NaBr and nonionic surfactant - Tween 80 reduced the binding strength, prevented the precipitation of the complex and increased the viscosity of the system. It was found that rheological properties are strong influenced by NaCMC-CTMAB interaction and the system exhibits either pseudoplastic or thixotropic or rheopectic behavior according to the intensity of interaction.

This paper evaluated the potential of zein–resins nanoparticles to act as a carrier for water‐insoluble oil carvacrol. The rosin and shellac were used as natural resins in different mass ratios to plant protein zein. Rosin is one of the natural gums. Shellac is a resinous secretion of the insect. The influence of nanoparticle composition on colloidal properties, encapsulation efficiency, and release of oil was studied. Zeta potential and size of thus prepared nanoparticles were studied. Carvacrol encapsulation efficiency and release were determined by the HPLC method developed for these compounds. Results showed that the resin type and share affect encapsulation efficiency and release of carvacrol. It was also shown that the addition of resins enhanced release from nanoparticles, compared to plain zein nanoparticles. Findings in the present work will help further understanding the interaction between alcohol–soluble biopolymers and provide new insight into the development of natural carriers for bioactive compounds. Novelty impact statement: Natural polymers derived from food are considered desirable materials for constructing delivery systems to encapsulate, protect, and release bioactive components in nutraceuticals, pharmaceuticals, and food. Therefore, this paper is approached to fabricate the carvacrol‐loaded zein/rosin (Z/R) and zein/shellac (Z/S) composite nanoparticles (NPs). Findings in the present work will help further understanding of the interaction between alcohol–soluble biopolymers (e.g., zein, rosin, and shellac) and provide new insight into the development of natural carriers for bioactive compounds. [ABSTRACT FROM AUTHOR]