The effect of encapsulated amount of caffeine on the mechanism of its release from hydrogels based on poly(methacrylic) and casein

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

Photoelectrochemical properties of sol–gel obtained titanium oxide

The photoelectrochemical properties of a sol–gel prepared titanium oxide coating applied onto a Ti substrate were investigated. The oxide coating was formed from an inorganic sol thermally treated in air at 350 °C. The coating consisted of agglomerates of narrow size distribution around 100 nm. The photoelectrochemical characteristics were evaluated by investigating the changes in the open circuit potential, current transients and impedance characteristics of a Ti/TiO2 electrode upon illumination by UV light in H2SO4 solution and in the oxidation of benzyl alcohol. The electrode was found to be active for photoelectrochemical reactions in the investigated solutions

Fifth European Dirofilaria and Angiostrongylus Days (FiEDAD) 2016

Peer reviewe

Physically Crosslinked Poly(methacrylic acid)/Gelatin Hydrogels with Excellent Fatigue Resistance and Shape Memory Properties

Hydrogels endure various dynamic stresses, demanding robust mechanical properties. Despite significant advancements, matching hydrogels’ strength to biological tissues and plastics is often challenging without applying potentially harmful crosslinkers. Using hydrogen bonds as sacrificial bonds offers a promising strategy to produce tough, versatile hydrogels for biomedical and industrial applications. Poly(methacrylic acid) (PMA)/gelatin hydrogels were synthesized by thermally induced free-radical polymerization and crosslinked only by physical bonds, without adding any chemical crosslinker. The addition of gelatin increased the formation of hydrophobic domains in the structure of the hydrogels, which acted as permanent crosslinking points. The increase in PMA and gelatin contents generally led to a lower equilibrium water content (WC), higher thermal stability and better mechanical properties. The values of tensile strength and toughness reached up to 1.44 ± 0.17 MPa and 4.91 ± 0.51 MJ m−3, respectively, while the compressive modulus and strength reached up to 0.75 ± 0.06 MPa and 24.81 ± 5.85 MPa, respectively, with the WC being higher than 50 wt.%. The obtained values for compressive mechanical properties are comparable with super-strong hydrogels reported in the literature. In addition, hydrogels exhibited excellent fatigue resistance and biocompatibility, as well as great shape memory properties, which make them prominent candidates for a wide range of biomedical applications

Prosodic Abilities and Phonological Working Memory in Swedish Preschool Children with Cochlear Implants

Cochleaimplantat (CI) är ett hörselhjälpmedel som kan ge barn med grav hörselnedsättning eller dövhet möjlighet att höra och utveckla talat språk. Svenska grundskolebarn med CI har tidigare visats ha en något nedsatt prosodisk förmåga och fonologiskt arbetsminne även om stora individuella variationer förekommer. Syftet med föreliggande studie var att undersöka prosodisk förmåga och fonologiskt arbetsminne hos svenska förskolebarn med CI. Vidare undersöktes samband mellan prosodisk förmåga och fonologiskt arbetsminne. I studien deltog sex förskolebarn med CI och totalt 18 normalhörande kontroller, varav sex var ålders-, köns- och dialektmatchade med barnen med CI. Barnen med CI i föreliggande studie uppvisade som grupp signifikant lägre resultat än de normalhörande barnen på test avseende prosodisk produktion på ord-, fras- och diskursnivå samt på test som undersöker fonologiskt arbetsminne. Gällande receptiv prosodisk förmåga förekom inga signifikanta skillnader. Vid jämförelse med svenska grundskolebarn med CI framkom att både yngre och äldre barn med CI har svårigheter med prosodi på samtliga nivåer. Vidare jämförelser indikerar att en utveckling av receptiv prosodisk förmåga sker under förskole- och skolåren. Korrelationsberäkningarna tyder på att det föreligger ett samband mellan prosodisk förmåga och fonologiskt arbetsminne. Barnen med CI i föreliggande studie är en heterogen grupp och några barn uppvisade på vissa deltest likvärdiga resultat som sina matchade kontroller, vilket visar att CI ger goda förutsättningar att utveckla prosodiska förmågor och talad kommunikation.Cochlear Implant (CI) is a hearing device that can enable deaf children or children with severe hearing impairment to hear and to develop spoken language. Research has shown that Swedish school aged children with CI have poor prosodic abilities to some extent, as well as poor phonological working memory. However, there are large individual differences. The aim of the present study was to investigate prosodic abilities and phonological working memory in Swedish preschool children with CI. Moreover, the relation between prosodic abilities and phonological working memory was examined. Six preschool children with CI participated in the study. The control group consisted of 18 children with normal hearing, out of which six children were matched for age, sex and regional dialect to the children with CI. In the present study the children with CI as a group demonstrated significantly lower results compared to the children with normal hearing on tests concerning prosodic production abilities at word, phrase and discourse level and tests concerning phonological working memory. No significant differences emerged regarding receptive prosodic abilities. In comparison to Swedish school aged children with CI it was shown that both younger and older children with CI have difficulties at all prosodic levels. Furthermore, the comparisons indicate that receptive prosodic skills develop during preschool and school years. Results also indicate a connection between prosodic abilities and phonological working memory. The children with CI in the present study is a heterogeneous group and a few children demonstrated equivalent results as their matched controls on some parts of the tests, which show that CI provides a good foundation for developing prosodic abilities and spoken communication

Core@Shell-Structured Binary TiO2@RuO2 Oxide Synthesized by Spray pyrolysis for Electrochemical Applications

The binary Ti02-Ru02 oxide is well-known constituent of the activated titanium anodes (ATA), crucial for their excellent electrocatalytic properties. There are efforts to improve the oxide synthesis procedure for highly controllable structural and consequently electrochemical performances of AT A coatings

pH-sensitive hydrogels based on poly(methacrylic acid), casein and liposomes for targeted delivery of poorly water-soluble active substances

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 SVA

Three dimensional polymeric networks based on poly(methacrylic acid) and protein for targeted delivery of poorly water-soluble drugs

Three dimensional polymer networks, hydrogels, have shown a great potential in controlled release and targeted delivery of active substances. pH sensitive hydrogels based on poly(methacrylic acid) have attracted significant attention due to their biocompatibility, non-toxicity and the possession of the huge number of ionogenic carboxylic groups. On the other hand, the usage of these hydrogels for controlled release and targeted delivery of poorly water-soluble drugs is limited by their highly hydrophilic nature. We overcame this limitation by modifying PMAA with amphiphilic substance - casein. The addition of this natural protein enabled the encapsulation, targeted delivery and controlled release of poorly water-soluble model drug - caffeine. Three carriers with different neutralization degree of methacrylic acid were synthesized via free radical polymerization. The FTIR spectra revealed that two types of interactions were established between casein and caffeine: hydrophobic interactions and hydrogen bonds. The SEM micrographs showed that the structure of the carriers depended on the change of neutralization degree of the methacrylic acid. The swelling of synthesized carriers and the caffeine in vitro release were monitored in two environments at 37°C: 0.1M HCl pH=1.2 (simulation of environment in human stomach) and phosphate buffer pH=6.8 (simulation of environment in human intestines). The synthesized carriers had higher swelling degree and the higher release rate of caffeine in the phosphate buffer pH=6.8 than in 0.1M HCl. The increase in neutralization degree of methacrylic acid caused the increase in swelling degree of the carriers and the increase in release rate of caffeine. Presented results showed that synthesized carriers are promising candidates for targeted delivery of poorly water-soluble drugs

The Mechanical Properties of a Poly(methyl methacrylate) Denture Base Material Modified with Dimethyl Itaconate and Di-n-butyl Itaconate

This study investigates a wide range of clinically relevant mechanical properties of poly(methyl methacrylate) (PMMA) denture base materials modified with di-methyl itaconate (DMI) and di-n-butyl itaconate (DBI) in order to compare them to a commercial PMMA denture base material. The commercial denture base formulation was modified with DMI and DBI by replacing up to 10 wt% of methyl methacrylate (MMA) monomer. The specimens were prepared by standard bath curing process. The influence of the itaconate content on hardness, impact strength, tensile, and thermal and dynamic mechanical properties was investigated. It is found that the addition of di-n-alkyl itaconates gives homogenous blends that show decreased glass transition temperature, as well as decrease in storage modulus, ultimate tensile strength, and impact fracture resistance with increase in the itaconate content. The mean values of surface hardness show no significant change with the addition of itaconates. The magnitude of the measured values indicates that the poly(methyl methacrylate) (PMMA) denture base material modified with itaconates could be developed into a less toxic, more environmentally and patient friendly product than commercial pure PMMA denture base material