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Preparation and properties of shellac-based hydrophobic coatings
No full textŠelak je prirodna, organska smola koju proizvode insekti koji obitavaju na stablima u Indiji i na Tajlandu. Smola koju oni izlučuju prolazi kroz razne faze pročišćavanja da bi se kao konačna sirovina dobio šelak, a ovisno o vrsti insekata, stablima i procesu pročišćavanja i obrade moguće je dobiti različite vrste šelaka, drugačijeg sastava, svojstava i boje. Primjenjuje se u raznim područjima kao što je u farmaciji, prehrambenoj industriji, zaštiti i premazu drvenih površina, kozmetici. Dodatak silana utjecao bi na poboljšanje svojstava šelaka. Cilj ovog rada bio je istražiti svojstva prevlaka mješavina šelaka (SCH) i dvaju silana
(3-glicidoksipropil-trimetoksisilan, GPTMS i 1,1,1,3,3,3-heksametildisilazan, HMDS) različitih udjela, pripremljenih iz otopine etanola, uz dodatak glicerola. Provedena su ispitivanja toplinskih svojstava primjenom diferencijalne pretražne kalorimetrije (DSC) i termogravimetrijske analize (TGA) i ispitivanja površinskih karakteristika mjerenjem kontaktnog kuta. Strukturna svojstva analizirana su pomoću FTIR-ATR spektroskopije,
a barijerna svojstva su određena mjerenjem propusnosti vodene pare te je ispitivana otpornost prevlaka na ljudski znoj. Utvrđeno je prema DSC analizi da dodatak silana povećava fleksibilnost prevlake i utječe na toplinsku stabilnost prevlaka prema TGA.
FTIR analiza ukazala je da nema značajnih razlika između prevlaka sa i bez silana. Kod prevlaka s ishodnim (krutim) šelakom, dodatkom silana propusnost vodene pare se povećala, odnosno kontaktni kut s vodom smanjio. Također, utvrđeno je da dodatkom silana topljivost prevlaka u otopini znoja raste te da silani nisu poboljšali tražena svojstva prevlaka.Shellac is a natural, organic resin produced by insects that live on trees in India and on Thailand. The resin they secrete goes through various stages of purification to obtain shellac as the final raw material and depending on the type of insects, trees and the process of purification and processing, it is possible to obtain different types of shellac, with different composition, properties and color. It is used in various fields such as pharmacy, food industry, protection and coating of wooden surfaces, cosmetics. Addition of silane would improve the properties of shellac. The aim of this work was to investigate the coating properties of mixtures of shellac (SCH) and two silanes (3-glycidoxypropyl-trimethoxysilane, GPTMS and 1,1,1,3,3,3-hexamethyldisilazane, HMDS) of different proportions, prepared from an ethanol solution, with addition of glycerol. Thermal properties were tested using differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA) and surface characteristics were tested by measuring the contact angle. The structural properties were analyzed using FTIR-ATR spectroscopy and the barrier properties were determined by measuring water vapor permeability and the coating's resistance to human sweat was tested. According to DSC analysis, it was determined that the addition of silane increases the flexibility of the coating and affects the thermal stability of the coating according to TGA. FTIR analysis showed that there are no significant differences between coatings with and without silanes. In the case of a coating with original (solid) shellac, the water vapor permeability increased with the addition of silane, that is, the contact angle with water decreased. Also, it was determined that with the addition of silane, the solubility of the coating in the sweat solution increases and that the silanes did not improve the required properties of the coating
Influence of additives on the rheological properties and oxidative stability of facial cream
No full textEmulzije su koloidni sustavi dvaju kapljevina, disperzne i kontinuirane faze. Smanjenje njihove termodinamičke nestabilnosti postiže se dodatkom površinski aktivnih tvari, odnosno emulgatora. Emulzije u kozmetici, poput krema za lice, kombiniraju vodu i ulje kako bi pružile hidrataciju i njegu koži. Oblik emulzije omogućava da se uljne i vodene komponente stabiliziraju, što rezultira u kremastoj teksturi koja se lako nanosi i brzo upija u kožu.
Osim toga, u ove emulzije su često dodani drugi sastojci poput antioksidansa, vitamina i konzervansa za dodatno poboljšanje zdravlja i izgleda kože. Cilj ovog rada bio je utvrditi utjecaj različitih emulgatora u formulacijama krema za lice na reološka svojstva i oksidacijsku stabilnost krema. Reološka ispitivanja provedena su na reometru, a oksidacijska stabilnost uzoraka određena je mjerenjem oksidacijske indukcijske temperature (OIT*) na DSC-u. Ispitivanja su provedena na formulacijama krema za lice s različitim emulgatorima i
ko-emulgatorima.Emulsions are colloidal systems of two immiscible liquids, dispersed and continuous phases. Reducing their thermodynamic instability is achieved by adding surfactants, or emulsifiers. Emulsions in cosmetics, such as face creams, combine water and oil to provide hydration and nourishment to the skin. The emulsion's structure allows the oil and water components to stabilize, resulting in a creamy texture that is easily applied and quickly absorbed into the skin. Additionally, other ingredients such as antioxidants, vitamins, and preservatives are often added to these emulsions for further improvement of skin health and appearance.
The aim of this study was to determine the influence of different emulsifiers in facial cream formulations on the rheological properties and oxidative stability of creams. Rheological tests were conducted on a rheometer, and the oxidative stability of samples was determined by measuring the oxidative induction temperature (OIT*) using DSC. The study was conducted on facial cream formulations with various emulsifiers and co-emulsifiers
Determination of ecotoxicity of phenol on Chlorella sp. and Pseudomonas putida
No full textPosljednjih godina povećana je emisija industrijskih otpadnih voda. S obzirom na izuzetno široku industrijsku primjenu fenola, fenolni spojevi prisutni su u velikim količinama u otpadnim vodama. Prisutnost fenola u vodi može imati toksične učinke kao rezultat antropogenih i prirodnih aktivnosti. Fenoli se najčešće bioakumuliraju prirodnim procesima i mogu narušiti bioekološku ravnotežu. Već u niskim koncentracijama, fenoli mogu negativno utjecati na ljudsko zdravlje, dok kratkotrajna izloženost visokim koncentracijama može dovesti do trovanja. Zbog visoke reaktivnosti fenola u vodenom mediju, koja je posljedica prisutnosti hidroksilne skupine, fenolni spojevi stupaju u interakciju s anorganskim komponentama vodenog okoliša i mikroorganizmima. Ekotoksikološke studije provode se kako bi se procijenili učinci fenola na vodene organizme. U ovom radu istražen je utjecaj ekotoksičnosti fenola na tri testna organizma, morsku bakteriju Vibrio fischeri, mikroalgu Chlorella sp. i bakteriju Pseudomonas putida. Ispitivane koncentracije fenola bile su: 100 mg/L, 75 mg/L,
50 mg/L, 25 mg/L, 10 mg/L i 1 mg/L. Tijekom eksperimenata mjerena je bioluminiscencija za bakteriju Vibrio fischeri, te broj živih stanica (CFU) mikroalgi i bakterije Pseudomonas putida tijekom 3 dana izlaganja. Cilj istraživanja bio je utvrditi ekotoksičnost fenola na tri testna organizma. Postotak inhibicije rasta mikroalge Chlorella sp. nakon 72 sata bio je 55,26 %, dok je inhibicija rasta Pseudomonas putida iznosila 46,97 %. Najveća inhibicija bioluminiscencije za bakteriju Vibrio fischeri od 84,52 % uočena je pri najvišoj ispitivanoj koncentraciji fenola (100 mg/L), te se može zaključiti da je Vibrio fischeri najosjetljiviji od ispitivanih testnih organizama.In recent years, the emission of industrial wastewater has increased. Given the extremely wide industrial use of phenol, phenolic compounds are present in large quantities in wastewater. The presence of phenol in water can have toxic effects as a result of anthropogenic and natural activities. Phenols are most frequently bioaccumulated by natural processes and can disturb the bioecological balance. Even at low concentrations, phenols can have a negative impact on human health, while short-term exposure to high concentrations can lead to poisoning. Due to the high reactivity of phenol in the water medium, which is due to the presence of the hydroxyl group, phenolic compounds interact with inorganic components of the water environment and microorganisms. Ecotoxicological studies are carried out to assess the effects of phenol on aquatic organisms. In this work, the influence of phenol ecotoxicity on three microorganisms, the marine bacterium Vibrio fischeri, the microalgae Chlorella sp. and the bacterium Pseudomonas putida, was investigated. The tested concentrations of phenol were: 100 mg/L, 75 mg/L, 50 mg/L, 25 mg/L, 10 mg/L and
1 mg/L. During the experiment, bioluminiscence was measured for the bacterium Vibrio fisceri, and the number of live cells (CFU) of microalgae and the bacterium Pseudomonas putida during 3 days of exposure. The aim of the study was to determine the ecotoxicity of phenol on three organisms. The percentage of growth inhibition of the microalgae Chlorella sp. after 72 hours was 55.26%, while the growth inhibition of Pseudomonas putida was 46.97%. The maximum growth inhibition of Vibrio fischeri was 84.52% at the highest tested concentration of phenol (100 mg/L), so it can be concluded that Vibrio fischeri is the most sensitive of the tested microorganisms
Nanotechnology in environment protection
No full textProblemi vezani uz onečišćenje okoliša poznati su od davnina. S intenzivnim razvojem industrije i zbog sve većeg utjecaja različitih antropogenih učinaka na okoliš dolazi do sve izraženijeg onečišćenja zraka, vode i tla te do narušavanja kvalitete života i prirodne bioraznolikosti. Zbog toga je važno utjecati na ljudsku svijest i smanjiti neželjene antropogene utjecaje na sve ekosustave, jer u suprotnom svijetu prijeti ekološka katastrofa, čiji smo svjedoci već danas. Trenutno postoje različiti pristupi smanjenju onečišćenja okoliša, koji u manjoj ili većoj mjeri pridonose rješavanju navedenih problema. Svaki takav pristup ima svoje prednosti i nedostatke, a željeni cilj se često pokušava ostvariti i kombinacijom različitih metoda i tehnologija. U novije vrijeme, sve stroži kriteriji zaštite okoliša koji su propisani nacionalnim i europskim zakonodavstvom nameću potrebu za poboljšanjem postojećih i razvojem novih učinkovitijih metoda i tehnologija. Prema mišljenju mnogih znanstvenika i stručnjaka znanost i tehnologija imat će važnu ulogu u razvoju naprednih metoda, alata i tehnika neophodnih za rješavanje specifičnih kvantitativnih i kvalitativnih problema u zaštiti okoliša. Posebno velika očekivanja postavljaju se na razvoj nanotehnologija, čime će se unaprijediti postojeće stanje i omogućiti budući razvoj održivih i ekološki prihvatljivih tehnologija. Trenutno se razvijaju različiti nanomaterijali i na njima utemeljene tehnologije, koji su prikladni za sanaciju onečišćenja u okolišu, najčešće zbog velike specifične površine i visoke reaktivnosti. Primjenom takvih materijala postižu se i bolji rezultati, jer zbog veće interakcije s onečišćujućim tvarima ili onečišćivalima dovode do brzog smanjenja koncentracije neželjenog onečišćenja u okolišu. Međutim, osim pozitivnih, postoje i negativni učinci zbog kojih takvi materijali u nekim situacijama mogu predstavljati rizik za okoliš i ljudsko zdravlje. Zbog toga je, kao i kod tradicionalnih tehnologija, potrebno unaprijed predvidjeti potencijalne opasnosti vezane uz njihovu primjenu te ih na vrijeme spriječiti. U ovom preglednom radu bit će analizirani specifični primjeri primjene naprednih nanomaterijala i na njima utemeljenih tehnologija, uključujući nano-adsorpciju, nano-filtraciju, nano-fotokatalizu te primjenu magnetskih nanočestica i nanosenzora. Poseban naglasak bit će dan na njihovu primjenu za pročišćavanje voda i otpadnih voda, pročišćavanje zraka i uklanjanje ostalih vrsta onečišćivala/zagađivala iz okoliša. S obzirom na brojne mogućnosti primjene takve tehnologije smatraju se zelenim tehnologijama i učinkovitim alatima za postizanje održivog razvoja. Osim pregleda postojećeg stanja u razvoju navedenih nanomaterijala, u ovom preglednom radu bit će razmatran i učinak nanotehnologija na zdravlje ljudi te analizirane mogućnosti sprječavanja mogućih rizika vezanih uz ljudsko zdravlje i kvalitetu života ljudi.Problems related to environmental pollution have been known for a very long time. With the intensive development of industrial production and due to the increasing influence of various anthropogenic impacts on the environment, there is an increasing pollution of air, water, and soil, as well as an impairment of quality of life and natural biodiversity. Therefore, it is important to raise human awareness of the issue and reduce unwanted anthropogenic impacts on all ecosystems, since otherwise the world is threatened by an ecological catastrophe, which we are already witnessing today. There are currently different approaches to reducing environmental pollution, which, to a greater or lesser extent, contribute to solving the problem. Each of these approaches has its advantages and disadvantages, and the desired goal is often tried to be achieved by combining different methods and technologies. More stringent environmental protection criteria recently prescribed by national and European legislation nowadays impose a need to improve the existing and develop new, more efficient methods and technologies. According to many scientists and experts, science and technology will play a significant role in the development of advanced methods, tools and techniques necessary to solve specific quantitative and qualitative problems in environmental protection. Particularly high expectations are placed on the development of nanotechnologies, which will improve the current situation and enable the future development of sustainable and environmentally friendly technologies. Nowadays, various nanomaterials and technologies based on them are being developed, suitable for remediation of environmental pollution, most often due to their large specific surface area and high reactivity. The use of such materials achieves better results, since due to the greater interaction with polluting substances or pollutants they lead to a rapid reduction in the concentration of unwanted pollution in the environment. However, beside these positive effects, there are also negative ones whereby such materials in certain circumstances can pose a risk to the environment and human health. Therefore, as with traditional technologies, it is necessary to anticipate potential hazards related to their application and prevent them in advance. The present review paper will analyse specific examples of the application of advanced nanomaterials and technologies based on them, including nano-adsorption, nano-filtration, nano-photocatalysis, and the application of magnetic nanoparticles and nanosensors. Special emphasis will be placed on their ability to purify water and wastewater, as well as the air, and to remove other different types of polluting substances/pollutants from the environment. Given the many possibilities of their application, such technologies are considered to be green and effective tools for achieving sustainable development. In addition to reviewing the current state of development of the said nanomaterials, the present review paper will also consider the impact of nanotechnologies on human health and analyse the possibilities for preventing possible risks related to human health and quality of life
Application of thermodynamics in the operation of nuclear power plants
No full textNuklearne elektrane su složeni sustavi koji zahtijevaju visoke sigurnosne standarde radi sprječavanja katastrofalnih nesreća i zaštite okoliša. Proizvodnja radioaktivnog otpada tijekom rada nuklearnih elektrana te potencijalne prijetnje uzrokovane ljudskim greškama ili prirodnim katastrofama predstavljaju operativne rizike. Kontinuirane analize i istraživanja za identifikaciju potencijalnih prijetnji su nužne za unaprjeđenje sigurnosnih mjera. Upravljanje radioaktivnim otpadom zahtijeva odgovarajuće metode zbrinjavanja kako bi se minimalizirali negativni utjecaji na okoliš i ljudsko zdravlje. Kroz kontinuirano istraživanje i razvoj, nuklearne elektrane mogu postati još pouzdaniji i održiviji izvor električne energije u budućnosti.Nuclear power plants are complex systems that require high safety standards to prevent catastrophic accidents and protect the environment. The production of radioactive waste during their operation and the potential threats posed by human error or natural disasters present operational risks. Ongoing analysis and research are essential for identifying potential threats and enhancing safety measures. Managing radioactive waste demands appropriate disposal methods to minimize negative impacts on the environment and human health. Through continuous research and development, nuclear power plants can evolve into even more reliable and sustainable sources of electricity in the future
Viscometric properties of poly(lactic acid) solutions
No full textViskozimetrijska svojstva od velike su važnosti pri karakterizaciji polimera i daju bitne polazne informacije za rad s polimernim materijalima. Poli(mliječna kiselina), PLA, je biorazgradljivi polimer od velike komercijalne važnosti. Zbog svoje biorazgradljivosti i biokompatibilnosti na veliko se koristi u biomedicini, npr. kao sustav za kontrolirano otpuštanje lijekova ili u tkivnom inženjerstvu kao okosnica/podloga za rast novog tkiva. Relativno je malo radova u kojima je provedena viskozimetrijska karakterizacija razrijeđenih otopina PLA, a rezultati takvih istraživanja su često kontradiktorni. U ovom diplomskom radu provedena je viskozimetrijska karakterizacija razrijeđenih otopina komercijalnih uzoraka poli(mliječne kiseline) u pet različitih otapala (kloroform, toluen, 1,4-dioksan, aceton i etil acetat). Na temelju dobivenih rezultata procijenjen je parametar topljivosti polimera te prosjeci molekulskih masa. Od svih istraživanih otapala kloroform se pokazao kao najbolje otapalo.Viscometric measurements are of great importance in the polymer characterization and provide essential initial information for working with polymer materials. Poly(lactic acid), PLA, is a biodegradable polymer of great commercial importance. Due to its biodegradability and biocompatibility, it is widely used in biomedicine, e.g. as a system for the controlled drug release or in tissue engineering as a scaffold for the growth of new tissue. There are relatively few works in which the viscometric characterization of diluted PLA solutions was carried out, and the results of such research are often contradictory. In this thesis, viscometric characterization of diluted solutions of commercial samples of poly(lactic acid) in five different solvents (chloroform, toluene, 1,4-dioxane, acetone and ethyl acetate) was performed. Based on the obtained results, the solubility parameter of the polymer and average molecular masses were estimated. Of all investigated solvents, chloroform proved to be the best solvent
The study of the antimicrobial activity of low density polyethylene/hematite composites
No full textPolimerni materijali imaju široku primjenu radi svoje pristupačnosti, niske cijene te mogućnosti lake prerade. Takvi materijali koriste se u svakodnevnoj upotrebi, kao što je ambalaža za različite proizvode, ali i u medicini, građevini, automobilskoj industriji i drugim područjima. Polietilen je jedan od najčešće korištenih polimernih materijala u izradi ambalaže s obzirom na prikladna svojstva, laku preradu i nisku cijenu. Prilikom pripreme polimernih materijala, nužan je dodatak različitih aditiva. Antimikrobna sredstva posebna su skupina aditiva koja sprečava nastanak i rast mikroorganizama na ambalaži i zapakiranom proizvodu. Na ovaj se način osigurava trajnost i kvaliteta proizvoda i očuvanje čovjekovog zdravlja. Uz titanijev dioksid i cinkov oksid, koji su učestalo korištene antimikrobne tvari, provode se i ispitivanja antimikrobnog djelovanja nekih drugih kemijskih spojeva. U ovom je radu ispitano antimikrobno djelovanje polimernih kompozita polietilena niske gustoće (LDPE) sa željezovim oksidom hematitom različitih veličina i oblika čestica. Provedena su ispitivanja na agar podlozi s gram-pozitivnim i gram-negativnim bakterijama Pseudomonas, Staphylococcus aureus te Bacillus Subtilis. Utvrđeno je da pojedine vrste pripremljenih kompozita LDPE/hematit pokazuju određeni stupanj antimikrobnog djelovanja i imaju potencijal za upotrebu kao ambalažni antimikrobni materijali.Polymer materials are widely used due to their accessibility, low cost and easy processing. They can be used in everyday life as packaging for various products, but also in medicine, civil engineering, automotive industry and other areas. Polyethylene is one of the most commonly used polymer materials as a packaging material due to its suitable properties, easy processing and low price. During the preparation of polymer materials, the addition of various additives is necessary. Antimicrobial agents are a special group of additives that prevent the formation and growth of microorganisms on the packaging. Such approach ensures durability and quality of the product and the preservation of human health. In addition to titanium dioxide and zinc oxide, which have been used as antimicrobial substances, tests of the antimicrobial effect of some other chemical compounds are also carried out. In this paper, the antimicrobial activity of polymer composites of low density polyethylene (LDPE) with iron oxide hematite of different particle sizes and shapes was tested. Tests were conducted on agar medium with gram-positive and gram-negative bacteria Pseudomonas, Stapyhlococcus aureus, and Bacillus Subtilis. It was found that some types of prepared LDPE/hematite composites show a certain degree of antimicrobial activity and have the potential for use as an antimicrobial packaging material
Fluorescent molecular sensors based on WHW peptide, triarylboranes and calixarenes
No full textMnoge male organske molekule su nekovalentni fluorescentni senzori za prepoznavanje DNA, RNA ili proteina te su od izuzetnog značaja za biomedicinsku dijagnostiku i istraživanja molekularne biologije. U ovom radu istraživane su interakcije tri različite grupe nekovalentnih fluorescentnih obilježivača pomoću spektroskopije UV/Vis, fluorescencije i cirkularnog dikroizma te temperaturne denaturacije s DNA, RNA i BSA. Prva grupa su analozi peptida triptofan-histidin-triptofan (WHW), karakterizirani zamjenom histidina s triazolilalaninom, te je kod dva nova analoga jedan triptofan zamijenjen pirenima. Ti analozi zadržali su visok afinitet peptida WHW prema Cu2+ kationu, ali i značajno viši afinitet prema DNA i RNA te BSA. Pirenski analozi pod UV svjetlom cijepaju DNA, zbog nastanka singletnog kisika. Ispitana je citotoksičnost sintetiziranih spojeva u suradnji s dr. Majhen s Instituta Ruđer Bošković. Analozi peptida WHW pokazali su slabu toksičnost in vitro na stanice zloćudnih tumora i normalne fibroblaste čovjeka, no bitno pojačanu pod UV svjetlom za pirenske analoge.
Druga grupa nekovalentnih fluorescentnih obilježivača se bazira na bis-triarilboranima, za koje je pokazano da s visokom osjetljivošću u 10 nM koncentracijama mogu detektirati i razlikovati DNA, RNA i BSA, simultano pomoću fluorescencije i površinski pojačane Ramanove spektroskopije (engl. surface-enhanced Raman spectroscopy, SERS). Ispitani tetrakationski bis-triarilborani s dugom bis(feniletinil)arilnom poveznicom pokazali su snažnu stabilizaciju ds-DNA i ds-RNA u eksperimentu temperaturne denaturacije, a kratki antracenski analog slabiju stabilizaciju, što je pokazalo važnost duljine i fleksibilnosti aromatske poveznice. Rezultati istraživanja dobivena uz pomoć cirkularnog dikroizma (CD) pokazala su da spoj čija je arilna poveznica 9,10-antracen uzrokuje odmotavanje uzvojite strukture polinukleotida pri vezanju i vrlo uniformiranu orijentaciju u odnosu na helikalnu os polinukleotida. Za treću grupu polikationskih kaliksarena i neutralnih analoga, dokazano je da pokazuju fluorescenciju u vodenom mediju, do sada nepoznato svojstvo kaliksarena. Dodatno, dokazano je da svi spojevi vežu mononukleotide (NMP) visokim afinitetom, stvarajući kompleks u obliku 'pincete'. Dobiveni odgovor je selektivan prema pirimidinskim bazama (uracil-monofosfatu i citozin-monofosfatu). S DNA i RNA u interakciju stupaju samo kationski analozi, ukazujući na značaj elektrostatskih interakcija s polianionskom okosnicom DNA/RNA. Eksperiment istiskivanja DAPI-ja iz DNA utora provedeno uz pomoć cirkularnog dikroizma (CD) pokazalo je također bolje istiskivanje uz pomoć kationskih kaliksarena. Dodatni eksperimenti cirkularnog dikroizma pokazali su kako umetanje kaliksarena ne utječe bitno na samu dvostruku uzvojnicu.Many small organic molecules, non-covalent fluorescent sensors for the recognition of DNA, RNA or proteins, are of great importance for biomedical diagnostics and molecular biology research. In this work, we have investigated the interactions of three different groups of non-covalent fluorescent markers using UV/Vis spectroscopy, fluorescence and circular dichroism as well as temperature denaturation with DNA, RNA and BSA. The first group are analogues of the tryptophan-histidine-tryptophan (WHW) peptide, characterized by the replacement of histidine with triazolyl-alanine, and in the two new analogs one tryptophan is replaced by pyrenes. These analogues retained a high affinity of WHW peptide towards the Cu2+ cation, but also a significantly higher affinity towards DNA, RNA and BSA. Pyrene analogues cleave DNA under UV light, due to the formation of singlet oxygen. The cytotoxicity of the synthesized compounds was tested in collaboration with Dr. Majhen from the Ruđer Bošković Institute. It was found that WHW peptide analogues showed weak toxicity in vitro on malignant tumor cells and normal human fibroblasts, which was significantly increased for pyrene analogs under UV light. The second group of non-covalent fluorescent labels is based on bis-triarylboranes, which have been shown to detect and differentiate DNA, RNA, and BSA at high sensitivity in 10 nM concentrations simultaneously using fluorescence and surface-enhanced Raman spectroscopy (SERS). Investigated tetracationic bis-triarylboranes with a long bis(phenylethynyl)aryl linker exhibited strong stabilization of ds-DNA and ds-RNA in the temperature denaturation experiment, while the short anthracene analog showed weaker stabilization, highlighting the importance of the length and flexibility of the aromatic linker. Circular dichroism (CD) results showed that the compound with a 9,10-anthracene aryl linker caused unwinding of the helical structure of polynucleotides upon binding and very uniform orientation relative to the helical axis of the polynucleotide. For the third group of polycationic calixarenes and neutral analogs, it was demonstrated that they exhibit fluorescence in an aqueous medium, an unknown property of calixarenes until now. Additionally, it was shown that all compounds bind mononucleotides (NMP) with high affinity, forming a 'tweezer-like' complex. The obtained response is selective towards pyrimidine bases (uracil monophosphate and cytosine monophosphate). Only cationic analogs interact with DNA and RNA, indicating the significance of electrostatic interactions with the polyanionic backbone of DNA/RNA. The displacement experiment of DAPI from DNA grooves conducted using circular dichroism (CD) also showed better displacement with cationic calixarenes. Additional circular dichroism experiments showed that the insertion of calixarenes does not significantly affect the double helix structure
Iron containing metallosurfactants
No full textCilj ovog rada bio je utvrditi utjecaj zamjene halogenidnih protuiona (Br⁻ i Cl⁻) s kompleksnim protuionom koji sadrži željezo na osnovna fizikalno-kemijska svojstva strukturno različitih PAT: monomernih dodecilpiridinijeva klorida (DPC) i dodeciltrimetilamonijeva bromida (DTAB), dimerne bis(N,N-dimetil-N-dodecil)etilen-1,2-diamonijeva dibromida (12-2-12) i dvolančane didodecildimetilamonijeva bromida (DDAB). U tu svrhu sintetizirane su nove PAT s kompleksnim protuionima: (DP)[FeCl4], (12-2-12)[Fe2OBr6] i (DDA)[FeBrCl3]. Općenito, uvođenjem metalnih iona u strukture konvencionalnih PAT nastaju jedinstveni spojevi koji osim sposobnosti adsorpcije i asocijacije posjeduju redoks, magnetska, i katalitička svojstva, s naglaskom na magentskim svojstvima u slučaju ugradnje iona željeza. Praćenjem termičkih promjena novosintetiziranih PAT pomoću stolića za grijanje i polarizacijskog mikroskopa (POM) utvrđeno je da ih karakteriziraju vrlo niska tališta, bliska sobnoj temperaturi, s izuzetkom dimerne (12-2-12)[Fe2OBr6]. Time spadaju u skupinu površinski aktivnih ionskih tekućina. Otopine novosintetiziranih PAT istražene su mjerenjem površinske napetosti Du Noüyevom metodom, mjerenjem električne provodnosti, a veličina i zeta potencijal micela određeni su dinamičkim (DLS) i elektroforetskim raspršenjem svjetlosti (ELS). Dobiveni rezultati pokazali su da zamjena halogenidnih protuiona s kompleksnim protuionom koji sadrži željezo ne utječe značajno na adsorpciju i asocijaciju istraženih PAT, neovisno o strukturi površinski aktivnog kationa. Rezultati dinamičkog i elektroforetskog raspršenja svjetlosti pokazali su da monomerna (DP)[FeCl4] i dimerna (12-2-12)[Fe2OBr6] PAT pri istim koncentracijama asociraju u veće asocijate, nižeg ζ potencijala, u odnosu na odgovarajuće ishodne PAT. Suprotan trend opažen je u sustavima dvolančane PAT, (DDA)[FeBrCl3].The aim of this study was to determine the impact of substituting halide counterions (Br⁻ and Cl⁻) with a complex counterion containing iron on the physico-chemical properties of structurally different surfactants: monomeric, dodecylpyridinium chloride (DPC) and dodecyltrimethylammonium bromide (DTAB), dimeric, bis(N,N-dimethyl-N-dodecyl)ethane- 1,2-diammonium dibromide (12-2-12), and double-chained, didodecyldimethylammonium bromide (DDAB). For this purpose new surfactants were synthesized: (DP)[FeCl₄], (12-2-12)[Fe₂OBr₆], and (DDA)[FeBrCl₃]. By introducing metal ions into surfactants' structure unique compounds are created, possessing magnetic, catalytic and redox properties, in addition to their adsorption and aggregation capabilities. Special emphasises is given on magnetic properties when iron ions are introduced. Thermal properties of the investigated surfactants were monitored using a heating stage and polarized optical microscope (POM), revealing that they are characterized by very low melting points, close to room temperature, with the exception of the dimeric (12-2-12)[Fe₂OBr₆]. Therefore, the synthesized surfactants fall into the category of surfaceactive ionic liquids. The solutions of the newly synthesized surfactants were investigated by measuring surface tension using the Du Noüy method, electrical conductivity was determined, and the size and zeta potential of micelles were determined by dynamic light scattering (DLS) and electrophoretic light scattering (ELS). The obtained results showed that the substitution of halide counterions with a complex counterion containing iron does not significantly affect the adsorption and association of the studied surfactants, regardless of the structure of the surfaceactive cation. The results of dynamic and electrophoretic light scattering indicated that monomeric, (DP)[FeCl₄], and dimeric, (12-2-12)[Fe₂OBr₆], surfactants self-assemble into larger aggregates with lower ζ potential, compared to their respective parent surfactants. An opposite trend was observed in the double-chained surfactant systems, (DDA)[FeBrCl₃]
Qualitative analysis of phenolic compounds in apple pomace by liquid chromatography
No full textJabuka je jedna od najrasprostranjenijih voćnih vrsta u svijetu i koristi se za svježu konzumaciju i proizvodnju različitih prerađevina. Prilikom prerade jabuka nastaje značajna količina nusproizvoda poznatog kao jabučna komina, koja ima potencijalnu nutritivnu vrijednost zbog prisutnosti mnogih hranjivih tvari, među kojima su i polifenoli, poznati po svojim antioksidacijskim svojstvima. Upravo zbog svog nutritivnog sastava, jabučna komina nalazi svoju primjenu u brojnim granama industrije, od prehrambene do farmaceutske. Iz tog razloga, cilj ovog rada je utvrđivanje primjene korisnih polifenola jabučne komine u svakodnevici te kvalitativna analiza polifenolnih spojeva u svrhu njezine daljnje oporabe. Istraživanje se provodilo na četiri različite sorte jabuka, a količine hranjivih tvari u jabučnoj komini dokazane su pomoću HPLC analize pojedinačnih fenolnih spojeva, te ukupnih fenolnih, flavonoidnih i neflavonoidnih spojeva. Navedeni rezultati dodatno su potkrijepljeni antioksidacijskim testovima metodama ABTS, FRAP i DPPH. Istraživanje ukazuje na veliki potencijal jabučne komine kao izvora prirodnih polifenola s primjenom u različitim industrijama. Rad pridonosi razumijevanju nutritivne vrijednosti jabučne komine i potencijala njenog korištenja u proizvodnji dodataka prehrani i drugih proizvoda. Rezultati istraživanja mogu poslužiti kao temelj za daljnje studije i komercijalne aplikacije polifenola dobivenih iz jabučne komine.The apple is one of the most widespread fruit species in the world, used both for fresh consumption and for the production of various processed products. The processing of apples produces a significant amount of byproduct known as apple pomace, which has potential nutritional value due to the presence of many nutrients, including polyphenols, known for their antioxidant properties. Due to its nutritional composition, apple pomace is used in numerous industries, from food to pharmaceuticals. For this reason, the aim of this study is to determine the application of the beneficial polyphenols in apple pomace in daily life and to perform a qualitative analysis of the polyphenolic compounds for further use.
The study was carried out on four different apple varieties and the amounts of nutrients in apple pomace were determined by HPLC analysis of the individual phenolic compounds as well as the total phenolic, flavonoid and non-flavonoid compounds. These results were also confirmed by antioxidant tests using the ABTS, FRAP and DPPH methods. The study shows the great potential of apple pomace as a source of natural polyphenols with applications in various industries. The study contributes to the understanding of the nutritional value of apple pomace and its potential use in the production of food supplements and other products. The research results can serve as a basis for further studies and commercial applications of polyphenols from apple pomace