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Ekološki prihvatljive nezasićene poliestarske smole sa svojstvima sličnim komercijalnim smolama dobijenim iz petrohemijskih sirovina u fokusu su novijih istraživanja zasnovanih na principima održivog razvoja. Jedan od glavnih izazova pri umreževanju je pravilan izbor inicijator/aktivator sistema za reakciju umrežavanja. U ovom radu je ispitan uticaj odnosa metil etil keton peroksida kao inicijatora i kobalt oktoata kao aktivatora na svojstva sintetisane nezasićene poliestarske smole na bazi itakonata. Utvrđen je optimalan sastav sistema inicijator/aktivator od 1,5:1,0 mas.%, pri kom je umrežena smola najveće zatezne čvrstoće i stepena umreženja. Pokazano je da povećanjem udela inicijatora u datom sistemu inicijator/aktivator od samo 4 puta dolazi do desetostrukog povećanja vrednosti zatezne čvrstoće., Novel research guided by sustainable development principles aims to generate eco-friendly unsaturated polyester resins with comparable properties to commercial petroleum-based resins. One of the main challenges encountered is the proper selection of the initiator/activator system for the crosslinking reaction. In this research, the influence of the ratio of methyl ethyl ketone peroxide as an initiator and cobalt octoate as an activator on the properties of the synthesized itaconate based unsaturated polyester resin was studied. The optimal composition of the initiator/activator system was found to be 1.5:1.0 wt.%, at which the cured resin showed the highest tensile strength and degree of crosslinking. It was further shown that a fourfold increase of initiator in a given initiator/activator system resulted in increased value of tensile strength by an order of magnitude.

The most abundant substance on the planet Earth and the main component of all living tissues is water. Mainly, the majority of materials in its natural conditions contain water either as chemically bound or retained in pores due to intermolecular interactions. However, water is also often deficient and the most sought-after substance on our planet. That is why the diverse methods for its recuperation and collecting have been extensively developed over time. Dehydration is a complex reversible and endothermic physicochemical process of removing water from the material, which takes place under conditions of simulated energy exchange (especially heat) and mass transfer between the material and the external environment. The most important feature of the dehydration process is the dominant influence of the dehydration product on the mechanism and kinetics of water removal from the material. Hydrogels are mainly defined as three-dimensional, cross-linked hydrophilic polymeric networks which have the ability to absorb a significant amount of water or other aqueous fluids (swelling) without dissolving or losing structural integrity. Hydrogels are extremely prominent against other polymeric materials because of their characteristic properties such as smart response to external stimuli, swelling ability, high water content, biocompatibility, adjustable porosity, and mechanical properties. Due to their unique properties, hydrogels found versatile applications. Knowledge and governing of the hydrogel dehydration process is of astonishing practical and theoretical importance. Due to high water content, hydrogels should be assumed as model systems suitable for modeling the description of the kinetics of dehydration of foods and living tissues. It is especially convenient that in the case of pH-sensitive hydrogels, the dehydration process can be initiated not only by the temperature increase but also by the pH-change of the medium. For example, anionic hydrogels will desorb in med

Novi trendovi u polimernoj industriji podstiču upotrebu sirovina dobijenih iz bioobnovljivih izvora kao i prelazak na zelenu tehnologiju. Nezasićene poliestarske smole su najzastupljenije termoreaktivne smole u proizvodnji polimernih kompozitnih materijala. Otpadni materijali, kao što su ljuske preostale od upotrebe kokošijih jaja, nastaju u velikim količinama, pri čemu ne predstavljaju opasan otpad zbog čega su korišćena kao punila za proizvodnju polimernih kompozitnih materijala. Za sintezu matrice korišćene su itakonska kiselina, ćilibarna kiselina, neopentil glikol, pri čemu je kao reaktivni rastvarač korišćen dimetil itakonat. Karakterizacija dobijenih kompozitnih materijala se sastojala od mehaničkog ispitivanja jednoosnim istezanjem kao i savijanjem u tri tačke, dok su promene u hemijskoj strukturi ispitivane FTIR spektroskopijom, a stepen umreženja je određivan analizom sadržaja gel faze., Development of biobased thermoset polymers encourages the strategic use of biobased resources and migrating to greener technologies. Unsaturated polyester resins have an extensive array of properties which makes them the most used thermoset resins in the production of polymer composite materials. Waste materials, such as eggshells left over from the usage of chicken eggs, are abundant and non-hazardous materials which offer many benefits in potential use as a filler in developing a biobased composite material. Itaconic acid, succinic acid, and neopentyl glycol were employed in unsaturated polyester synthesis, while dimethyl itaconate was used as a reactive diluent. Characterization of the resulting composite materials included assessing mechanical properties (uniaxial tensile test, three-point bending test), FTIR spectroscopy, and gel content analysis.

Everyday struggle of humanity with novel diseases and present once, urge researchers to find novel and improve existing therapies to enhance their efficiency and safety. One of the promising approaches to overcome these challenges is controlled release of drugs. Biomaterials based on poly(methacrylic acid) (PMAA) are excellent drug delivery systems because they can control release rate and released amount of drug. Also, due to their pH sensitivity the PMAA hydrogels can release drug at the site of action. Namely, these nontoxic and biocompatible hydrogels swell in the environment with pH value higher than pKa of PMAA (4.6) and release encapsulated drug during the process. In present study, PMAA hydrogels are synthetized under ambient conditions by simple, cost effective and eco-friendly synthesis. Novel initiation system based on hydrogen peroxide, potato peel peroxidase and vitamin C (VC) is used for the first time for free radical polymerization of PMAA hydrogel. In accordance with the principles of circular economy, peroxidase was isolated from potato peel waste by water extraction for 12 h at 4 ℃. Four PMAA hydrogels were prepared by using potato peel peroxidase with various enzyme activity (0.4; 0.8; 1.2 and 1.8 IU), whereas the amounts of H2O2 (30 mL) and VC (10 mg) have been kept constant. The composition of the PMAA hydrogels was confirmed by FTIR analysis, whereas their porous structure was revealed by SEM. The swelling of the PMAA hydrogels was monitored in two media: 0.1M HCl (as simulation of human stomach) and phosphate buffer with pH 7.4 (as simulation of human intestines). In order to encapsulate anti-inflammatory drug – dexamethasone into the PMAA hydrogels, the hydrogels were immersed into the dexamethasone aqueous solution (5 mg/ml) and left to swell to the equilibrium, after which they were dried at room temperature. Dexamethasone release from the PMAA hydrogels was monitored in the same environments as was the PMAA swelling. The results showed th

Controlled release of drugs is a promising tool for improvement of therapy for many diseases because drug concentration for long period of time is kept constant, whereas number of drug doses and side effects are reduced. pH sensitive hydrogels, such as hydrogels based on poly(methacrylic acid) (PMAA), are extensively employed for drug delivery. The synthesis of the hydrogel is one of the most important factors which affect encapsulation of drug and its bioactivity. In present study, we investigate if the encapsulation of poorly water-soluble active substance (caffeine) during the synthesis of PMAA hydrogels, and later its controlled release from the PMAA hydrogels, can be achieved by applying novel ”green” method for the hydrogels preparation. The PMAA hydrogels with encapsulated caffeine and various amount of crosslinker are prepared by free radical polymerisation in aqueous solution and ambient conditions by using novel initiation system based on hydrogen peroxide and vitamin C. The swelling behaviour of the PMAA hydrogels and controlled release of caffeine are investigated in two media with pH 1 and pH 6.8 as simulation of human stomach and intestines, respectively. The SDeq values of the PMAA hydrogels are eight times higher in the medium with pH 6.8 and as a consequence, three times higher amount of caffeine is released in that medium. The increase in the crosslinker amount leads to the decrease of SDeq values of the PMAA hydrogels and amount of released caffeine. The results show that the PMAA hydrogels have great potential for controlled release of poorly water-soluble drugs.

Modern society are faced with lot of challenges in the treatment of many diseases, especiallywith serious ones such as cancer. Safer and more efficient treatment of the cancer patients are maingoals which researchers are aiming. One of the good approaches can be drug delivery systems.Still, a lot of anticancer drugs are poorly water-soluble and their encapsulation and controlled releasecan be quite challenging. Present study is focused to improve drug delivery system based onhydrophilic poly(methacrylic acid) and amphiphilic casein with encapsulated poorly water-solublecaffeine, which has been developed through our previous research. The hydrogels with 1.6mol% ofcrosslinker and 100% of neutralization degree of methacrylic acid are synthetized (PMAC-100N-4M). The swelling process of the PMAC-100N-4M hydrogels and caffeine release are analyzed intwo environments which simulate human stomach and intestines. It is also investigated how thechange in the encapsulated caffeine weight and the addition of liposomes with encapsulated caffeine,affect swelling degree of the PMAC-100N-4M hydrogels and release of caffeine. The resultsshow that controlled release of caffeine is improved, therefore overall therapy can be enhanced., Savremeno društvo je suočeno sa mnogim izazovima u tretamanu raznih bolesti, naročito ozbiljnih oboljenja kao što je rak. Glavni ciljevi naučnika su da se postigne bezbednija i efikasnija terapija pacijenata koji se leče od raka. Jedan od dobrih načina da se to postigne su sistemi za dostavu lekova. Ipak, mnogi antikancerogeni lekovi su slabovodorastvorni, pa bi veliki izazov mogao da bude inakpsulacija i njihovo kontorlisano otpuštanje iz sistema za dostavu lekova. Cilj ovog rada je da se unapredi sistem za dostavu lekova na bazi hidrofilne poli(metakrilne kiseline) i amfifilnog kazeina sa inkapsuliarnim slabo vodorastvornim kofeinom, koji je razvijen tokom našeg prethodnog istraživanja. U ovom radu sintetisani su hidrogelovi sa 1,6mol% umreživača i 100% neutralisanom metakrilnom kiselinom (PMAC-100N-4M). Procesi bubrenja PMAC-100N-4M hidrogelova i kontrolisanog otpuštanja kofeina su ispitivani u dve sredine koje simuliraju želudac i tanko crevo čoveka. Takođe je ispitano kako promena količine inkapsuliranog kofeina i dodatak lipozomne suspenzije sa inkapsuliranim kofeinom utiče na procese bubrenja PMAC-100N-4M hidorgelova i otpuštanje kofeina. Rezultati pokazuju da je proces kontrolisanog otpuštanje kofeina unapređen, a samim tim je moguće unaprediti i celokupnu terapiju.

The preparation of zeolite rich polymeric materials presents a challenge due to the zeolite settlingduring synthesis, poor miscibility, the phase separation and generally insufficient interactionsbetween polymers and zeolites. Combination of LTA, i.e. MFI, zeolite and poly(methacrylic acid) in theform of soft hydrogel network provided the stabilization of the zeolite particles and enabled synthesisof composite hydrogels with very high zeolite concentrations (26-52 mass%).The investigated morphological, mechanical and primary structural properties, water swelling abilityand thermal stability revealed high dependence on zeolite concentration and type. Zeolite particleswere uniformly dispersed in PMAA matrix as confirmed by SEM and there was no agglomeration orzeolite leaching despite very high concentrations. FTIR spectra disclosed the existence of functionalgroups of PMAA network and both zeolite types that interacted mutually and led to increasedcrosslinking density. The established interactions changed the PMAA chain dynamics around theparticles, especially of the LTA type, as showed by XRD. Having much more surface groups capable togenerate interaction with PMAA, LTA zeolite stronger affected all of the investigated properties.Composites’ mechanics was improved both in dry and swollen state compared to the PMAA hydrogel(up to 21.8 times for the sample with the highest LTA concentration). Thermal stability of thecomposites increased with increasing zeolite concentration.The composition-property correlations were determined making this work the base for furtherdevelopment of tailor-made zeolite-PMAA composite hydrogels aimed for specific application.Composites were tested as low-cost, regenerative, environmentally friendly sorbents and showedbetter removal of cationic dye compared to both components (PMAA and zeolite) alone.

The preparation of zeolite rich polymeric materials presents a challenge due to the zeolite settling during synthesis, poor miscibility, the phase separation and generally insufficient interactions between polymers and zeolites. Combination of LTA, i.e. MFI, zeolite and poly(methacrylic acid) in the form of soft hydrogel network provided the stabilization of the zeolite particles and enabled synthesis of composite hydrogels with very high zeolite concentrations (26-52 mass%). The investigated morphological, mechanical and primary structural properties, water swelling ability and thermal stability revealed high dependence on zeolite concentration and type. Zeolite particles were uniformly dispersed in PMAA matrix as confirmed by SEM and there was no agglomeration or zeolite leaching despite very high concentrations. FTIR spectra disclosed the existence of functional groups of PMAA network and both zeolite types that interacted mutually and led to increased crosslinking density. The established interactions changed the PMAA chain dynamics around the particles, especially of the LTA type, as showed by XRD. Having much more surface groups capable to generate interaction with PMAA, LTA zeolite stronger affected all of the investigated properties. Composites’ mechanics was improved both in dry and swollen state compared to the PMAA hydrogel (up to 21.8 times for the sample with the highest LTA concentration). Thermal stability of the composites increased with increasing zeolite concentration. The composition-property correlations were determined making this work the base for further development of tailor-made zeolite-PMAA composite hydrogels aimed for specific application. Composites were tested as low-cost, regenerative, environmentally friendly sorbents and showed better removal of cationic dye compared to both components (PMAA and zeolite) alone.

Materials sensitive to external stimuli are recognized as safe and effective tool able to respond to specific demands in the therapy of various diseases. Thermo sensitive hydrogels based on poly(N-isopropylacrylamide) (P(NIPAAM)) are widely investigated for targeted drug delivery. Still, the abundance of the stimuli in the human body often requires more than one responsive group able to act simultaneously to achieve optimal therapeutic effects. Due to its pH sensitivity and bio-based production, crotonic acid (CA) was a monomer of choice for preparation of eco-friendly copolymer hydrogels based on NIPAAM and CA (P(NIPAAMcoCA)), which turned to be thermo and pH sensitive at the same time. The potential of the P(NIPAAMcoCA) system for encapsulation and controlled release of drugs with different solubility was investigated engaging water-soluble lidocaine hydrochloride and poorly water-soluble ibuprofen as model drugs. The hydrogels were characterized by various technics: FTIR, DSC, SEM and single compressive tests, while swelling behavior and controlled release of the drugs were analyzed with respect to the CA amount in two environments with different pH values at 25 °C and 37 °C. It was demonstrated that due to their dual responsiveness the P(NIPAAMcoCA) hydrogels have potential for controlled release of drugs with different solubility.

Researchers are faced with everyday demands for safer and more efficient therapy for many diseases, especially serious one such as various types of cancer. Numerous anticancer drugs are poorly-water soluble and therefore their encapsulation and controlled release remain quite challenge. In present study, we deepened our research of hydrophilic carrier based on poly(methacrylic acid) and casein (PMAC) by investigating its potential for encapsulation and controlled release of novel poorly water-soluble dihydropyrimidion-azo-pyridon compound (DHPMP). DHPMP is a dye that has been proven to show cytotoxic activity against chronic myeloid leukemia K562 cells. By encapsulating DHPMP into the carrier and delivering it into the intestines, DHPMP absorption could be the fastest and the number of therapeutic doses and side effects can be reduced. Carriers based on PMAC and DHPMP (PMAC-DHPMP) were synthetized and characterized by FTIR, SEM and single compression tests. The swelling behavior of PMAC-DHPMP carriers and cumulative DHPMP release were investigated depending on the amount of crosslinker and encapsulated DHPMP in two media which were simulating pH environments in human stomach and intestines. The prolonged and controlled release of DHPMP was achieved. In vitro cytotoxic activity of PMAC-DHPMP carriers against K562 cells and the cell cycle analysis showed great potential of the carriers for application in leukemia treatment.

Pectin and pectin derived oligosaccharides can be obtained from waste apple pomace(biomass). Traditional method for pectin extraction involves use of diluted mineral acids atelevated temperatures, with yields of about 10 to 15%. As an alternative to conventionalmethods, the use of eutectic solvents is increasing because of their superior propertieswhen it comes to targeted extraction of certain components from biomass. The aim of thispaper is ultrasound assisted extraction of pectin from waste apple pomace using cholinechloride based eutectic solvents and lactic acid. Properties of extracted products wereexamined using FTIR spectroscopy and differential scanning calorimetry., Pektin i pektinski oligosaharidi mogu se dobiti iz otpadne jabučne kaše. Ovaj prirodni polimer ima široku primenu u industriji. Tradicionalna metoda za ekstrakciju pektina podrazumeva tretman razblaženim mineralnim kiselinama na povišenoj temperaturi, pri čemu se prinosi ostvaruju od oko 10 do 15%. Kao alternativa tradicionalnim rastvaračima sve češće se koriste i eutektički rastvarači, koje odlikuju daleko superiornija svojstva kada je reč o ciljanoj ekstrakciji određenih komponenti iz biomase. Cilj ovog rada je ultrazvučna ekstrakcija pektina primenom eutektičkih rastvarača na bazi holin hlorida i mlečne kiseline. Svojstva ekstrahovanog proizvoda ispitana su primenom FTIR spektroskopije i diferencijalne skenirajuće kalorimetrije.

Inteligentni hidrogelovi, kao što su pH osetljivi hidrogelovi na bazi poli(metakrilne kiseline) (PMAA), imaju veliku primenu u ciljanoj dostavi lekova. Međutim, slaba mehanička svojstva često ograničavaju primenu PMAA. Kako bi se prevazišlo navedeno ograničenje, nanoceluloza (NC) je prvo ekstrakovana iz drvnog otpadnog materijala, a zatim dodata u PMAA, zato što je NC biokompatibilna, netoksična i ima odlična mehanička svojstva. Zatim je dodata karboskimetil celuloza (CMC) (celulozni derivat koji se često koristi za kontrolisano otpuštanje lekova). CMC može da stabilizuje nanočestice magnetita (MN) koje su takođe dodate. MN mogu značajno da poboljšaju mehanička svojstva hidrogelova i takođe poseduju magnetna svojstva zbog čega imaju primenu za ciljano otpuštanje lekova. Ovako dobijeni materijal bi mogao da zaštiti lek, dostavi ga do mesta delovanja, kontroliše brzinu njegovog otpuštanja i na taj način omogući efikasno dejstvo leka sa smanjenim neželjenim efektima. Lokalni anestetik – lidokain hidrohlorid (LH) se često u tretmanima injektira što može imati ozbiljne neželjene efekte. Inkapsulacijom LH u hidrogelove na bazi PMAA, NC, CMC i MN (PMNC/MN-L) rešen je navedeni problem. Karakterizacija PMNC/MN-L hidrogelova je izvedena primenom FTIR i SEM spektroskopija i kompresionim testovima, a zatim je analizirano bubrenje hidrogelova i otpuštanje LH. U ovom radu predstavljen je jedinstveni način „zelene” sinteze hibridnih hidrogelova osetljivih na spoljne stimulanse unapređenih svojstava i njihove primene za kontrolisano otpuštanje lokalnog anestetika sa smanjenim neželjnim efektima.

Drug delivery system is an amazing tool which is widely used for drugprotection and its controlled release in order to enhance drug bioavailability,reduce side effects and therefore to improve overall therapy. Hydrogels havebeen attracted great attention as drug carriers due to their great physicochemicalproperties, similarity to the living tissues and biocompatibility. One group ofpH sensitive hydrogels are based on poly(methacrylic acid) (PMAA). Thesenon-toxic hydrogels are used as drug delivery system because they swell asa response to the change in pH of external environment and drug is beingreleased during the process. In present study, in order to improve the control ofdrug release rate, caffeine was encapsulated in liposomes which were furtherembedded into PMC hydrogel (PMCL). It was investigated how the change inneutralization degree of methacrylic acid affect the swelling degree of PMCLhydrogels and caffeine release in two environments at 37 °C for 24 h: 0.1 Mhydrochloride acid (pH 1) and phosphate buffer with pH value of 6.8 (pH 6.8), asa simulation of pH environment in human stomach and intestines, respectively.Obtained results show that PMCL hydrogels have great potential for controlledrelease of poorly water-soluble drugs in human intestines.

Everyday demands for safer and more efficient therapy for many diseases, especially serious ones such as various types of cancer, put various challenges in front of modern science. One of them lies in the fact that numerous anticancer drugs are poorly-water soluble and therefore their encap-sulation and controlled release are quite demanding processes. In the present study, we deepened our research of carrier based on hydrophilic poly(methacrylic acid) modified with amphiphilic ca-sein, in which poorly water-soluble model drug caffeine was encapsulated (PMAC-Caf hydrogels). It was investigated how neutralization degree of methacrylic acid (MAA) and amount of encapsulated caffeine affected swelling behavior of the PMAC-Caf hydrogels and caffeine release. Easy, one pot, simultaneous synthesis of the carrier and the encapsulation of caffeine is presented, obtaining thereby as prepared PMAC-Caf drug delivery system that could respond to the specific demands of the tar-geted delivery of the poorly water-soluble drug - protecting it in the environment which simulated human stomach and releasing it in the environment which simulated human intestines. Changing the synthesis parameters (neutralization degree of MAA and/or amount of encapsulated caffeine) we achieved controlled release of caffeine, indicating that the number of the required doses of the drug in the treatment and its side effects could be reduced. Results showed that the PMAC-Caf drug deliv-ery systems have huge potential for controlled release of poorly water-soluble drugs.

Researchers are making everyday efforts to develop new drugs or improve present ones in order to enhance therapies of various diseases, especially serious ones like cancer. Drug delivery systems (DDS) are one of the solutions for safer and more efficient therapy. Hydrogels based on poly(methacrylic acid) (PMAA) are extensively investigated as DDS due to their nontoxicity, biocompatibility and pH sensitivity. Many chemotherapeutics are poorly watersoluble, so it is quite challenging to encapsulate them into highly hydrophilic PMAA. In our previous study we overcome this limitation by modifying PMAA with amphiphilic casein and demonstrated that poorly water-soluble model drug – caffeine can be successfully encapsulated and released in control manner from these samples (H hydrogels). In present study we go step forward and investigated how the change in the amount of encapsulated caffeine affect the mechanism of caffeine release from the H hydrogels in medium with pH of 6.8 (which simulates the environment in human intestines). Commonly used models for the analysis of kinetics of drug release from hydrogels: Ritger-Peppas, Higuchi and Kopcha model are employed for the analysis of the mechanism of caffeine release. Presented results indicate that it is possible to adjust the manner and mechanism of drug release by changing the amount of encapsulated drug, due to which the H hydrogels can adapt to the unique requirements of the therapy.

Drug delivery system is an amazing tool which is widely used for drug protection and its controlled release in order to enhance drug bioavailability, reduce side effects and therefore to improve overall therapy. Hydrogels have been attracted great attention as drug carriers due to their great physicochemical properties, similarity to the living tissues and biocompatibility. One group of pH sensitive hydrogels are based on poly(methacrylic acid) (PMAA). These non-toxic hydrogels are used as drug delivery system because they swell as a response to the change in pH of external environment and drug is being released during the process. In present study, in order to improve the control of drug release rate, caffeine was encapsulated in liposomes which were further embedded into PMC hydrogel (PMCL). It was investigated how the change in neutralization degree of methacrylic acid affect the swelling degree of PMCL hydrogels and caffeine release in two environments at 37 °C for 24 h: 0.1 M hydrochloride acid (pH 1) and phosphate buffer with pH value of 6.8 (pH 6.8), as a simulation of pH environment in human stomach and intestines, respectively. Obtained results show that PMCL hydrogels have great potential for controlled release of poorly water-soluble drugs in human intestines.

Pectin and pectin derived oligosaccharides can be obtained from waste apple pomace (biomass). Traditional method for pectin extraction involves use of diluted mineral acids at elevated temperatures, with yields of about 10 to 15%. As an alternative to conventional methods, the use of eutectic solvents is increasing because of their superior properties when it comes to targeted extraction of certain components from biomass. The aim of this paper is ultrasound assisted extraction of pectin from waste apple pomace using choline chloride based eutectic solvents and lactic acid. Properties of extracted products were examined using FTIR spectroscopy and differential scanning calorimetry.

Processing of waste by-products of agricultural origin generated by different kinds of industries can entail environmental problems. Waste apple pomace (biomass) could play an important role in pectin production, offering economic advantages and decreasing the environmental impact. Pectin and pectin derived oligosaccharides have many applications in food and pharmaceutical products as gelling agents and stabilizers. Traditional method for pectin extraction involved the use of diluted mineral acids at elevated temperatures, with yields of about 10 to 15%. Because of the relatively long period of exposure to direct heating, thermal degradation of pectin often occurs in this process. The use of deep eutectic solvents could be the solution to this problem. Deep eutectic solvents have shown superior properties when it comes to targeted extraction of certain components from biomass, while providing mild conditions when compared to conventional methods. The aim of this paper is thermal extraction of pectin from waste apple pomace using choline chloride based deep eutectic solvents combined with different acids (oxalic acid, lactic acid and malic acid). Properties of extracted products were examined using FTIR spectroscopy and differential scanning calorimetry.

Targeted drug delivery is powerful tool which researchers use to achieve safer and more efficient therapy of many diseases, including various types of cancer. Many chemotherapeutics are poorly watersoluble, so their encapsulation and targeted delivery remain quite challenge. Hydrogels based on poly(methacrylic acid) (PMAA) are widely investigated for targeted drug delivery due to their pH sensitivity, non-toxicity and biocompatibility. Still, due to the PMAA highly hydrophilic nature, PMAA can only be used for encapsulation and targeted delivery of water-soluble drugs. Our previous research was directed towards overcoming this limitation: PMAA was modified with amphiphilic protein – casein and poorly-water soluble model drug – caffeine – was encapsulated (PMAC). Present study is focused on investigation how variation of amount of one of the most important hydrogels network parameter such as crosslinker affect PMAC swelling properties and caffeine release. The group of hybrid hydrogels – PMAC – was synthesized with various amount of crosslinker: 0.4mol%, 0.8mol%, 1.6mol% and 3.2mol% with respect to methacrylic acid. Swelling behavior of hybrid hydrogels and caffeine release was investigated in two environments which simulated human stomach and intestines. Obtained results showed that targeted delivery of poorly water-soluble model drug was achieved and that its release can be prolonged up to 24h. Also, kinetic of poorly water-soluble drug release can be easily modified only by changing crosslinker amount. PMAC hybrid hydrogels have huge potential for targeted delivery of poorly water-soluble active substances.

pH- and magnetic-sensitive hybrid hydrogels based on poly(methacrylic acid) (PMAA), nanocellulose (NC), carboxymethyl cellulose (CMC) and magnetite particles (MN) were prepared as ibuprofen delivery system. NC was isolated from wood waste material and added to highly hydrophilic PMAA in order to improve the mechanical properties of PMAA and enable the encapsulation of poorly water-soluble ibuprofen. CMC was added in order to stabilize magnetite particles. The pH- and magnetic-sensitivity of the obtained hybrid hydrogels (originated from PMAA and MN, respectively) provided targeted delivery and controlled release of ibuprofen. Hybrid hydrogels were characterized by various technics: FTIR, SEM, XRD, VSM, the modified Faraday method, photon correlation spectroscopy and by using single compression tests. The swelling behavior of hybrid hydrogels and cumulative ibuprofen release were investigated depending on wt% of NC and MN in two media which were simulating pH environments in human stomach and intestines. The swelling degree of hybrid hydrogels and the percent of cumulative ibuprofen release decreased with the increase in wt% of NC. The same was found for increasing wt% of MN. Ibuprofen release kinetics was investigated with Korsmeyer–Peppas model. The obtained results showed that the prepared green dual responsive hybrid hydrogels were excellent candidates for the controlled release of ibuprofen, showing that the release kinetic can be easily tuned by changing only one hydrogel component.

Schiff bases, or azomethine compounds, are commonly employed in the fields of organic synthesis, metal complexes, materials, and engineering. Especially, they have gained importance in medicinal researches, considering their antimicrobial, anticancer, antiinflammatory, and antioxidant properties. On the other side, azo dyes are the most significant group of synthetic dyes, utilized in textile fiber dyeing. Conjugation of Schiff bases with azo compounds leads to the class of azo-azomethine dyes, which have numerous applications related to their coloration and biological properties. Viscose is a textile material widely used in the medicine. Moreover, viscose fiber can be engineered in many ways which are significant in the development of medical materials. The antioxidant effect is an important feature of medical textiles, such as wound dressings. In this work, the microwave-assisted synthesis and characterization of novel azo-azomethine dye are reported. The azo-azomethine dye is obtained by the condensation between arylazo pyridone dye and 4-aminophenol. The structure of synthesized dye was determined by ATR-FTIR, NMR, and UV-Vis spectroscopy. Azoazomethine dye was used for dyeing viscose, and the washing fastness of dyed material was evaluated according to the standard method. The viscose fabrics, before and after washing, were analyzed in terms of their color coordinates in the CIELab color space. The antioxidant properties of azo-azomethine dye and dyed viscose fabrics were examined by the ABTS method.

Polymeric carriers for targeted delivery of poorly water-soluble active substances (PWSAS) are facing two challenges. First, encapsulation of PWSAS depends on structure of the carrier. Second limitation is caused by the phenomenon of burst drug release. Despite the fact that the fast release of drug in a burst stage is utilized in certain drug administration strategies, the negative effects brought about by burst can be pharmacologically dangerous and economically inefficient. This study presents a novel strategy for encapsulation and targeted delivery of PWSAS - caffeine without the possibility of burst effect. Hydrophilic carrier based on poly(methacylic acid) was modified by amphiphilic substances - casein and centrifuged liposomes to ensure caffeine encapsulation. The caffeine was encapsulated in liposomes which further were incorporated into the carrier networks during the synthesis of the carriers. The release kinetic of caffeine was analyzed with respect to morphology of the carriers and interactions that could be established between the components of the carrier. The swelling of carriers and release of caffeine were further investigated depending on the neutralization degree of methacrylic acid in two media with different pH simulating the path of the carrier through the upper and lower human gastrointestinal tract. Synthesized carriers showed significant potential for encapsulation and targeted delivery of PWSAS., Kod razvoja polimernih nosača za ciljano otpuštanje slabo vodorastvornih aktivnih supstanci (SVAS) postoje dva ograničenja. Prvo, inkapsulacija SVAS zavisi od strukture nosača. Drugo ograničenje je vezano za naglo oslobađanje leka. Uprkos činjenici da je naglo oslobađanje leka, tzv. burst efekat poželjno kod nekih sistema, negativni efekti naglog oslobađanja leka u većini slučajeva mogu biti farmakološki opasni i ekonomski neefikasni. U ovom radu je prikazana nova strategija za inkapsulaciju i ciljano otpuštanje SVAS – kofeina bez burst efekta. Hidrofilni nosač na bazi poli(metakrilne kiseline) je modifikovan amfifilnim supstancama – kazeinom i centrifugiranim lipozomima kako bi se postigla inkapsulacija kofeina. Kofein je inkapsuliran u lipozome koji su zatim inkorporirani u mrežu nosača tokom sinteze nosača. Analiziran je uticaj morfologije nosača i interakcija koje su se uspostavile između njegovih komponenti na kinetiku otpuštanja kofeina. Zatim je analiziran uticaj stepen neutralizacije metakrilne kiseline na bubrenje nosača i otpuštanje kofeina u dve sredine različitih pH vrednosti koje su simulirale pH sredinu u gastrointestinalnom traktu čoveka. Pokazano je da sintetisani nosači imaju veliki potencijal za inkapsulaciju i ciljano otpuštanje SVAS