Search

Design of efficient drug delivery system which can protect drug, preserve its activity, improve its bioavailability, and release it in control manner still presents quite challenge. Encapsulation of drug during the synthesis of drug delivery system is especially complex part. In our previous research we have developed simple and eco-friendly synthesis of hydrogels based on poly(methacrylic acid) that employing hydrogen peroxide and vitamin C (H2O2/VC) as initiator. Present study investigates if the encapsulation of lidocaine hydrochloride during the synthesis of hydrogel and later its con-trolled release, can be achieved by using this method. Results show that mild synthesis conditions enable efficient encapsulation of lidocaine hydrochloride and synthesis of hydrogels based on poly(methacrylic acid) (PMAAL). Lidocaine hydrochloride is local anesthetic which is used in anesthesia and in antiarrhythmic therapy, and it is usually applied by injection. Its encapsulation and controlled release from the hydrogels present good solution to overcome unpleasantness during its application and to reduce required number of dosages. Obtained PMAAL hydrogels are further char-acterized by employing FTIR and SEM analysis, as well as single compression tests. PMAAL swelling and controlled release of the drug are analyzed in two environments with pH 1 and pH 6.8 simulating pH environments in human stomach and intestines. The results show that around eight times higher amount of lidocaine hydrochloride is released in environment with pH 6.8 due to the pH dependent swelling of the PMAAL hydrogels. The change in crosslinker amount on the PMAAL swelling and drug release are also investigated. The increase in the crosslinker amount lead to the decrease of amount of drug released from the PMAAL hydrogels. This study shows that the method which employing H2O2/VC as initiator can be used for efficient encapsulation of lidocaine hydrochloride. Also, this drug can be released in controlled man, Razvoj efikasnog sistema za dostavu lekova koji može da zaštiti lek, sačuva njegovu aktivnost, poboljša njegovu biodostupnost i kontrolisano ga otpušta predstavlja još uvek pravi izazov. Inkapsu-lacija leka tokom sinteze sistema za otpuštanje leka je posebno zahtevan deo. U našem prethodnom radu razvili smo jednostavnu i ekološki prihvatljivu sintezu hidrogelova na bazi poli(metakrilne kise-line) kod koje se kao inicijator koristi sistem vodonik peroksid i vitamin C (H2O2/VC). U sadašnjem istraživanju se ispituje da li se može postići inkapsulacija lidokain hidrohlorida tokom sinteze hidro-gela i kasnije njegovo kontrolisano oslobađanje. Rezultati su pokazali da su blagi uslovi sinteze o-mogućili efikasnu inkapsulaciju lidokain hidrohlorida i sintezu hidrogelova na bazi poli(metakrilne kiseline) (PMAAL). Lidokain hidrohlorid je lokalni anestetik koji se koristi kod anestezije i kod tera-pije aritmije, a najčešće se pacijentima daje injekcijom. Njegovo inkapsuliranje i kontrolisano oslo-bađanje iz hidrogelova predstavljaju dobro rešenje kako bi se sprečile neprijatnosti do kojih dolazi tokom njegove administracije i kako bi se smanjio broj doza potrebnih za terapiju. Karakterizacija dobijenih PMAAL hidrogelova je zatim izvedena primenom FTIR i SEM analize, kao i ispitivanjem otpornosti ovih materijala na kompresiju. Bubrenje PMAAL hidrogelova i kontrolisano oslobađanje leka analizirani su u dve sredine sa pH 1 i pH 6,8, koje su simulirale pH sredine u ljudskom želucu i crevima. Rezultati pokazuju da se oko osam puta veća količina lidokain hidrohlorida oslobađa u sredini sa pH 6,8 zbog pH osetljivog bubrenja PMAAL hidrogelova. Takođe je ispitan uticaj promene količine umreživača na bubrenje PMAAL hidrogelova i otpuštanje leka. Povećanje količine umreži-vača dovodi do smanjenja otpuštene količine. Ovo istraživanje pokazuje da metoda kod koje se koristi H2O2/VC kao inicijator može da se koristi za efikasnu inkapsulaciju lidokain hidrohlorida. Takođe, ovaj lek se može ko

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 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.

Composite hydrogels are the subject of intensive research due to there specific 3D cross-linked structure with extraordinary physical and chemical properties which enables variety of applications In spite of increasing interest for using different external fields in physical-chemical processes, three are no available literature data about the effects of external fields on swelling and swelling kinetics of hydrogels. Therefore, the effects of (conventional) thermal (TH), ultrasonic (US) and microwave (MW) fields, on the swelling degree and swelling kinetics. A sample of poly(methacrylic acid) (PMAA) xerogel with 10%wt of LTA-zeolite (PMMA-LTA) was synthesized and thoroughly characterized. The isothermal kinetic swelling curves were determined within a temperature range T= 293-323K in the TH, US and MW fields. The results were well fitted with the Peppas’ kinetic model. At all applied fields, with an increase in temperature, there is an increase in the equilibrium swelling degree (SDeq) and the swelling rate constant (k), while the parameter of Pepass's model (n) decreases. The maximum value of SDeq and parameter n is achieved at TH, while the US assisted process leads to the maximum value of k. The minimum value of the activation energy (Ea) and at the same time the maximum value of the pre-exponential factor (lnA) lnA were achieved by applying the MW field. The influence of US and MW fields on the diffusion of water molecules through the polymer network, activation of the polymer network for swelling and relaxation of the polymer network was analysed.

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.

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.

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.

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.

Targeted drug delivery is powerful tool which researchers use to achieve safer and more efficienttherapy of many diseases, including various types of cancer. Many chemotherapeutics are poorly watersoluble, so their encapsulation and targeted delivery remain quite challenge. Hydrogels based onpoly(methacrylic acid) (PMAA) are widely investigated for targeted drug delivery due to their pHsensitivity, non-toxicity and biocompatibility. Still, due to the PMAA highly hydrophilic nature, PMAAcan only be used for encapsulation and targeted delivery of water-soluble drugs. Our previous researchwas directed towards overcoming this limitation: PMAA was modified with amphiphilic protein –casein and poorly-water soluble model drug – caffeine – was encapsulated (PMAC). Present study isfocused on investigation how variation of amount of one of the most important hydrogels networkparameter such as crosslinker affect PMAC swelling properties and caffeine release. The group ofhybrid 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 andcaffeine 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 andthat its release can be prolonged up to 24h. Also, kinetic of poorly water-soluble drug release can beeasily modified only by changing crosslinker amount. PMAC hybrid hydrogels have huge potential fortargeted 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.

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

The sustainable tomorrow for future generations lies with the present industrial development toward the proper utilization of various bio-based products. For a transition to a higher level of sustainability, it is necessary to form a new platform for advanced technology products. This paper reports the development of new fully bio-based unsaturated polyesters resins (UPRs). A series of prepolymers were synthesized by varying saturated diacids (oxalic, succinic and adipic acid), itaconic acid and 1,2-propandiol. Dimethyl itaconate was used as a reactive diluent (RD) in amounts of 30, 35 and 40 wt%. Rheological measurements showed that the obtained resins possessed viscosities (234-2226 mPa s) amenable to a variety of liquid molding techniques. The impact of composition variables-prepolymer structure and amount of RD-on the chemical, mechanical and thermal properties of the thermosets was examined by DMA, TA and tensile measurements and was discussed in detail. The tensile properties (37-52 MPa), glass transition temperature (60-97 A degrees C) and coefficient of thermal expansion (71-168 10(-6) A degrees C-1) of the cured resins were in the desired range for UPRs. This investigation showed that UPRs based on itaconic acid can be tailored during synthesis of the prepolymer to meet the needs of different property profiles.

Cilj ove studije bio je ispitivanje hidrofobnog karaktera i mehaničkih svojstava filmova na bazi modifikovanog pektina. Modifikovani pektin dobijen je u reakciji esterifikacije između hidroksilnih grupa pektina i di-acil hlorida (glutaroil i sebacoil hlorid). Filmovi su pripremani iz vodenih rastvora dobijenih derivata (2% w/v) metodom otparavanja rastvarača. Procena hidrofobnog karaktera dobijenih derivata data je na osnovu merenja vrednosti kontaktnog ugla vodene kapi na površini uzorka u formi filma (sessile drop method). Utvrđeno je da hidrofobnost i mehanička svojstva filmova zavise od stepena acilovanja kao i dužine umetnutog ugljeničnog lanca., Present study reports the evaluation of hydrophobic character and mechanical performances of the films based on modified pectin. The pectin modifications were obtained in esterification reaction between hydroxyl groups from pectin and di-acyl chlorides (glutaryl and sebacoyl chloride). The films were prepared from water solutions of the resulted derivatives (2% w/v) using solvent casting method. The hydrophobicity of the obtained films was evaluated through the quantification of the contact angle (sessile drop method). It was found that the surface as well as mechanical properties were affected by acylation degree and length of the inserted carbon chains.

For the preparation of fully biobased unsaturated polyester resins (UPRs), the replacement of styrene with alternate nonpetroleum-based monomers turned out to be one of the most challenging tasks. Its complexity lies in the fact that reactive diluents (RD) have to have low viscosity and volatility, good compatibility with prepolymer, and capability to homopolymerize and copolymerize with its unsaturations. In this context, we directed our efforts to develop fully biobased UPRs using the dialkyl itaconates as an alternative to styrene. Therefore, a series of 100% biobased UPRs were prepared from itaconic acid and 1,2-propandiol and diluted by dialkyl itaconates. The resins were characterized by Fourier transform infrared spectroscopy, NMR, volatility, and viscosity measurements, while the cured samples were characterized by dynamic mechanical properties, thermomechanical analysis, thermogravimetric analysis data, and tensile tests. The influence of RD structure on the properties of cured samples was discussed in detail. It was shown that the prepared resins had evaporation rates of dialkyl itaconates of several orders of magnitude less compared to styrene. The cured resins with dimethyl itaconate showed comparable or even better thermal and mechanical properties compared to the one with styrene. This investigation showed that itaconic acid and dialkyl itaconates are promising bioresources for the preparation of fully biobased UPRs for mass consumption.

Mimicking the extraordinary performances of natural materials presents an attractive, but challenging approach in the synthesis of advanced functional materials. In the field of separation techniques, the design of a low-cost, regenerative, environmentally friendly sorbent and the utilization of most of its active centers to remove the targeted pollutant are everyday challenges. The combination of casein and poly(sodium methacrylate) (PMANa) in the form of a soft polymer network is proposed as a promising sorbent for the removal of Ni2+ from wastewater. Such a combination and an applied synthetic route form hybrid materials with better sorption properties than both their components alone. SEM and TEM show that caseinate micelles are dissociated and the more exposed protein structure is stabilized by the PMANa network and able to form various stable complexes. The achieved sorption capacity (224 mg g(-1)) is among the highest reported in the literature. The very high removal efficiency in the wide range of the initial Ni2+ concentrations (0.05-200 ppm) and easy and complete regeneration without decrease in sorption capacities make these low-cost materials highly sensitive sorbents attractive for use under real conditions where it is necessary to avoid environmental risks and provide the recovery and reuse of the metal.

In this study novel copolymer hydrogels based on methacrylic acid (MAA) and 2-acrylamido-2-methylpropane sulfonic acid (AMPS) were synthesized by free-radical aqueous copolymerization and characterized. Derived P(MAA-co-AMPS) hydrogels, joining well the affection of numerous anionic groups toward cations and the accessibility of active sites in the swollen network were recognized as potential sorbents for removal of cationic species. The effect of various initial parameters on sorption of two cationic dyes onto P(MAA-co-AMPS) hydrogels was investigated in both, single and binary, systems. Results showed that the copolymerization of MAA and AMPS significantly increased sorption capability of copolymers compared to both pure-component hydrogels-PMAA and PAMPS hydrogels. The main advantage of novel copolymer hydrogels is enhanced sorption of dyes in binary systems, reaching maximal values of 98.8% (Basic Yellow 28) and 96.4 (Basic Red 46), onto hydrogel P (MAA-co-AMPS) 50/50. The desorption rate of BY28 and BR46 in both, single and in binary, systems increased with the increase in AMPS content in hydrogels. This investigation showed that copolymerization of two acidic monomers, bearing different types of acid groups, could significantly improve the sorption thus decreasing the price and the amount of material needed for successful removal of pollutants. (C) 2015 Elsevier B.V. All rights reserved.

Hidrogelovi predstavljaju trodimenzionalno umrežene polimere koji imaju sposobnost da apsorbuju veliku zapreminu vode ili fizioloških tečnosti. Zahvaljujući prisustvu hidrofilnih grupa kao što su –OH, –CONH, –CONH2, –COOH ili –SO3H mogu da sadrže i do više hiljada puta veću masu vode u odnosu na masu suvog uzorka pri čemu njihova struktura ostaje nepromenjena. Hidrogelovi na bazi metakrilne kiseline spadaju u grupu pH-osetljivih hidrogelova. Ovi pH-osetljivi hidrogelovi bubre i do 700 puta u vodi, u odnosu na svoju početnu zapreminu. Hidrogelovi na bazi metakrilne kiseline su našli primenu u biomedicini, za otpuštanje aktivnih materija i selektivno vezivanje različitih jona i njihovo uklanjanje iz rastvora, za proizvodnju higijenskih proizvoda, u poljoprivredi itd1 . Hidrogelovi na bazi 2-akrilamido-2- -metilpropansulfonske kiseline (AMPS) poseduju visok stepen hidrofilnosti u širokom opsegu pH zbog prisustva sulfonske grupe u svojoj strukturi, dok prisustvo dimetil grupe pruža termičku stabilnost. Visok stepen apsorcije vode i sposobnost bubrenja omogućili su široku primenu hidrogelova na bazi AMPS-a 2 . Ovi hidrogelovi su biokompatibilni, imaju uniformnu provodljivost, kohezionu snagu, postižu zadovoljavajuću adheziju na koži zbog čega se koriste u medicini kao komponente zavoja, za izradu elektrokardiografskih i defibrilacijskih elektroda. Kopolimeri AMPS-a i drugih hidrofilnih monomera, kao što su akrilna kiselina, itakonska kiselina ili N-vinil pirolidin, su ispitivani za primenu u preradi otpadnih voda3,4.Cilj ovog rada je dobijanje novog hidrogela na bazi metakrilne kiseline i AMPS-a, koji posedovanjem 2 različite funkcionalne grupe u svojoj strukturi može povećati efikasnost prečišćavanja obojenih otpadnih voda naspram referentnih hidrogelova PMAA i PAMPS., In this study novel copolymer hydrogels based on methacrylic acid and 2-acrylamido-2-methylpropane sulfonic acid were synthesized by free-radical aqueous copolymerization at 70 °C for 5 hours. These hydrogels were characterized by FTIR spectroscopy, equilibrium swelling degree and sorption of Basic Yellow 28 and Basic Red 46 dye in single and binary system. The ratio of comonomers in reaction mixture affected the properties of resulting copolymers, as the equilibrium swelling degree increased with the increase in AMPS content in hydrogel. The synthesized hydrogels showed better sorption in binary system compared to the sorption of these dyes in single system, probably due to different ability of hydrogel functional groups to interact with cationic dyes. The maximal percent removal of Basic Yellow 28 and Basic Red 46 dyes were observed by P(MAA-coAMPS) 50/50 hydrogel and reached values of 96.4% and 98.3%, respectively. Desorption of BY28 and BR46, in both, single and binary system increased with the increase of AMPS content in hydrogel.

The use of polymeric adsorbents for the removal of azo dyes from solution has been reviewed. Adsorption techniques are widely used to remove certain classes of pollutants from waters, especially those which are not easily biodegradable. The removal of azo dyes as pollutants from wastewaters of textile, paper, printing, leather, pharmaceutical and other industries has been addressed by the researchers. The wider use of already available adsorbents is restricted due to their high costs which lead to investigation and development of new materials that can be cheaper, eficient and easy regenerated. The aim of this article is to present to the readers the widespread investigations in recent years of synthetic and natural polymers as adsorbents and potential replacement of conventional adsorbents. This review presents only the data obtained using raw, hydrogel, grafted and crosslinked forms of synthetic and nature based polymers, and the discussion is limited to these polymer-based materials and their adsorption properties.

U prvom delu ovog rada sintetisani su hidrogelovi na bazi delimično i potpuno neutralisane metakrilne kiseline, radikalnom polimerizacijom i umrežavanjem na 80 °C, konvencionalno i pod dejstvom mikrotalasnog polja. Primenom ova dva načina sinteze i variranjem eksperimentalnih parametara, sintetisani su makroporozni materijali sa veoma različitim karakteristikama, morfologijom, osnovnim strukturnim parametrima, mehaničkim svojstvima i ponašanjem pri bubrenju, što je pokazano njihovim karakterisanjem primenom infracrvene spektroskopije sa Furijeovom transformacijom (FTIR), skenirajude elektronske mikroskopije (SEM), dinamičko-mehaničke analize (DMA) i pradenjem kinetike bubrenja. Nakon analize i optimizacije dobijenih rezultata, konvencionalnom radikalnom polimerizacijom su sintetisani kompozitni hidrogelovi na bazi PMAA matrice sa stepenom neutralizacije monomera od 80% i neorganskih punila, tipa zeolita A i ZSM-5 u koncentracijama 10-30 mas%. Karakterisanje dobijenih kompozita izvršeno je FTIR, DMA i termogravimetrijskom analizom (TGA), SEM mikroskopijom i pradenjem ponašanja pri bubrenju i dehidrataciji pod uticajem različitih eksperimentalnih uslova: pH medijuma, temperature, dejstva ultrazvučnog i mikrotalasnog polja. Utvrđeno je da je zeolit ravnomerno raspoređen u PMAA matrici, kao i da su ostvarene interakcije fizičke, najverovatnije vodonične veze. Utvrđeno je i da su sintetisani kompoziti boljih mehaničkih svojstava, bržeg odziva i vede termičke stabilnosti, pH-osetljivi, dok su u ispitivanom temperaturnom opsegu potpuno neosetljivi na promenu temperature ukoliko nisu izloženi dejstvu utrazvučnog ili mikrotalasnog polja. Ispitana je mogudnost uklanjanja katjonske boje basic yellow 28 (BY28) sorpcijom iz vodenih rastvora na sintetisanim hidrogelovima, kao i uticaj stepena neutralizacije monomera, prisustva, vrste i koncentracije zeolita u kompozitnim hidrogelovima na uspešnost uklanjanja navedene boje, pod različitim eksperimentalnim uslovima, kao i kinetika, In the first part of this work hydrogels based on partially and completely neutralized methacrylic acid were synthesized by free-radical polymerization and crosslinking at 80 °C, conventionally and in microwave field. By using these two methods of synthesis and by varying the experimental parameters, macroporous materials with very different characteristics, morphology, the basic structural parameters, mechanical properties and swelling behavior, were synthesized as demonstrated by characterizing them using Fourier Transform Infrared Spectroscopy (FTIR), Scanning Electron Microscopy (SEM), Dynamic-mechanical analysis (DMA) and by monitoring the kinetics of swelling. After analysis and optimization of the obtained results composite hydrogels based on PMAA matrix with the neutralization degree of monomer of 80% and inorganic fillers, of zeolite A and ZSM-5 type at concentrations of 10-30 wt% were synthesized conventionally. The characterization of the obtained composites was performed by FTIR, thermogravimetric (TGA) and DMA analysis, SEM microscopy and by monitoring the swelling behavior and dehydration at different solution pH, temperature and under effects of ultrasonic and microwave fields. It is found that the zeolite particles are distributed uniformly in the PMAA matrix and that the established interactions are physical, probably hydrogen bonds. It is also found that the composites with better mechanical properties and higher thermal stability, sensitive to change of solution pH, while completely insensitive to temperature changes in the investigated temperature range unless they are exposed to ultrasound or microwave field, were synthesized. The possibility of removing of the cationic dye basic yellow 28 (BY28) from wastewater by sorption onto synthesized hydrogels, and the effect of the monomer neutralization degree, presence, type and concentration of zeolite in the hydrogels, on the efficiency of the removal of BY28 under different experimental conditions

Electrocatalytic properties of RuO2/Ti anode with different coating masses, which are prepared by the alkoxide sol-gel procedure, are investigated in chlorine and oxygen evolution reactions by polarization measurements and electrochemical impedance spectroscopy in H2SO4 and NaCl electrolytes. According to polarization measurements, the activity of anodes at overpotentials below 100 mV is independent of coating mass. However, impedance measurements above 100 mV reveal changes in the activity of anodes in chlorine evolution reaction for different coating masses. The diffusion limitations related to the evolved chlorine are registered in low-frequency domain at 1.10 V (SCE), diminishing with the increase in potential to the 1.15 V (SCE). The observed impedance behavior is discussed with respect to the activity model for activated titanium anodes in chlorine evolution reaction involving formation of gas channels within porous coating structure. Gas channels enhance the mass transfer rate similarly to the forced convection, which also increases the activity of anode. This is more pronounced for the anode of greater coating mass due to its more compact surface structure. The more compact structure appears to be beneficial for gas channels formation.