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Citric acid-crosslinked gelatin/hydroxypropyl methylcellulose hydrogels for biomedical applications
Get PDFINTRODUCTION: Hydrogels, characterized by their three-dimensional hydrophilic polymer networks capable of retaining substantial amounts of water or biological fluids, hold significant promise for biomedical and pharmaceutical applications. While numerous polymers have been explored for hydrogel development, those derived from natural sources possess inherent advantages due to their abundance, affordability, biocompatibility, and biodegradability. Gelatin, a widely used natural polymer in biomedicine, standsout for its cost-effectiveness, compatibility with biological systems, and degradability. Hydroxypropyl methylcellulose (HPMC), a cellulose derivative, exhibits hydrophilicity, biodegradability, and biocompatibility. However, natural polymer-based hydrogels often exhibit low mechanical strength and solubility in physiological conditions, necessitating innovative cross-linking strategies to enhance their functionality. Citric acid (CA) emerges as a promising crosslinking agent owing to its affordability andnon-toxic nature.EXPERIMENTAL:HPMC-G hydrogels were synthesized by dissolving gelatin (0.05 g) and HPMC (0.1 g) with specified amounts of CA and sodium hypophosphitein 1 ml of distilled water in a reaction vessel. The mixture was homogenized, poured into a Teflon mold, and frozen at -20°C for 24 hours. After lyophilization, the hydrogels underwent crosslinking at 160°C for 7 minutes. By varying the CA content from 0%to 40% (w/w) while maintaining constant temperature and time, the optimal CA/HPMC ratio was determined. Subsequently, various heat treatments (140–180°C, 3-12 minutes) were applied to explore the optimal curing conditions.RESULTS AND DISCUSSION:The investigation elucidates how the CA/HPMC ratio and curing conditions impact the physicochemical and mechanical propertiesof HPMC-G hydrogels. Swelling tests and compressive mechanical property evaluations reveal that the incorporation of citric acid, along with increases in curing temperature and time, enhances compressive modulus and degradation stability while reducing equilibrium swelling. Scanning electron microscopyanalysis reveals a highly porous microstructure in the resulting hydrogels, while differential scanning calorimetrycurves indicate the formation of strong interactions between gelatin and HPMC.CONCLUSIONS:The utilization of these materials notonly contributes to environmental conservation efforts but also drives the advancement of eco-friendly technology, aligning with the principles of the circular economy. Moreover, it offers promising avenues for innovative solutions in potential biomedicalapplications.ExcellMater Conference 2024: Innovative Biomaterials for Novel Medical Devices, Belgrade, Serbia, April 10-12, 202
Effects of different doped hydroxyapatite‐based materials on healing of critical size calvaria bone defects in rats
Get PDFNanosized synthetic hydroxyapatite (HAp), closely resembling biological apatite found in human bones and teeth, is extensively studied for its potential in hard tissue repair. Ion-doping of HApwith therapeutic ions is emerging as a promising strategy to mimic biologicalapatite, promoting specific biological responses such as osteogenesis, angiogenesis, increased cell proliferation, and antimicrobial activity[1]. The aim of our study was to explore and compare the effects of Sr,Cu co-doped α tricalcium phosphate (αTCP)with/without Mg doped HAP on healing of critical size rat calvaria defects in vivo.ExcellMater Conference 2024: Innovative Biomaterials for Novel Medical Devices, Belgrade, Serbia, April 10-12, 202
Phytochemical Analysis, Biological Activities, and Molecular Docking Studies of Root Extracts from Paeonia Species in Serbia
No full textWithout being aware of their chemical composition, many cultures have used herbaceous peony roots for medicinal purposes. Modern phytopreparations intended for use in human therapy require specific knowledge about the chemistry of peony roots and their biological activities. In this study, ethanol–water extracts were prepared by maceration and microwave- and ultrasound-assisted extractions (MAE and UAE, respectively) in order to obtain bioactive molecules from the roots of Paeonia tenuifolia L., Paeonia peregrina Mill., and Paeonia officinalis L. wild growing in Serbia. Chemical characterization; polyphenol and flavonoid content; antioxidant, multianti-enzymatic, and antibacterial activities of extracts; and in vitro gastrointestinal digestion (GID) of hot water extracts were performed. The strongest anti-cholinesterase activity was observed in PT extracts. The highest anti-ABTS (2,2′-azino-bis(3-ethylbenzothiazoline-6-sulphonic acid) radical potential was observed in PP extracts, whereas against DPPH (2,2-diphenyl-1-picrylhydrazyl radicals), the best results were achieved with PO extracts. Regarding antibacterial activity, extracts were strongly potent against Bacillus cereus. A molecular docking simulation was conducted to gather insights into the binding affinity and interactions of polyphenols and other Paeonia-specific molecules in the active sites of tested enzymes. In vitro GID of Paeonia teas showed a different recovery and behavior of the individual bioactives, with an increased recovery of methyl gallate and digallate and a decreased recovery of paeoniflorin and its derivatives. PT (Gulenovci) and PP (Pirot) extracts obtained by UAE and M were more efficient in the majority of the bioactivity assays. This study represents an initial step toward the possible application of Paeonia root extracts in pharmacy, medicine, and food technologies
Aging effect on surface chemistry and sorption properties of atmospheric pressure plasma treated lignocellulosic jute fibers
No full textJute fibers are characterized by a heterogeneous chemical composition (cellulose and non-cellulosic components) and a complex layered structure with a hydrophobic surface outer layer responsible for their low wettability. In this work, after the removal of water-soluble components, raw jute fibers were subjected to atmospheric pressure dielectric barrier discharge (DBD) under different conditions (at 150 or 300 Hz) to tailor jute fiber surface structure and wettability. The research was focused on the aging effect during natural aging in a standard atmosphere investigated up to three weeks after DBD treatment. Alterations in the surface morphology of DBD-treated jute fibers were investigated by FE-SEM and AFM, while ATR-FTIR, XPS, and electrokinetic measurements were used to assess the changes in the jute fiber surface chemistry. Sorption properties were monitored through wetting time and capillary rise measurements. The sorption properties of DBD-treated jute fibers were improved (about 100 times lower wetting time and 15 % higher capillary rise height in comparison to untreated) due to the changes in surface chemistry (decreased lignin and hemicellulose content in parallel with cellulose oxidation) and morphology (about 4.6 times higher average roughness). The electrokinetic and sorption properties measurement confirmed the significance of aging effects in lignocellulosic fibers' functionalization using plasma
Fine-Tuning Bimetallic Nanostructures for Enhanced Hydrogen Evolution Reaction
No full textWater electrolysis, powered by electricity obtained from renewable sources, emerges as a pivotal method for green hydrogen production, a crucial energy vector. However, its widespread adoption faces challenges due to high energy consumption and resultant high costs attributed to the substantial overpotential of electrochemical reactions, specifically cathodic hydrogen evolution (HER) and anodic oxygen evolution (OER) reactions [1].
In this study, we introduce a novel electrocatalyst for HER, comprising RuIr nanoparticles supported on nitrogen-doped titanium oxide integrated into reduced graphene oxide (RuIr/TiON-C). The electrochemical activity and stability of RuIr/TiON-C are thoroughly examined in both alkaline and acidic environments and compared to RuIr/C analog as well as Ru/C, Ir/C, and Pt/C benchmarks. In alkaline electrolyte, RuIr/TiON-C outperforms all other tested materials whereas in acidic media it performs similarly to Pt/C, the current leading catalyst for HER in acid. Furthermore, RuIr/TiON-C demonstrate robust HER performance during potentiodynamic and potentiostatic degradation tests. The enhanced HER activity and stability of the investigated material can be linked to two effects: alloying of Ru and Ir and strong metal metal-support interaction (SMSI) triggered between the TiONx support and RuIr nanoparticles. The synergy of these two factors results in increased catalytic activity for the hydrogen evolution reaction
PACKAGING BASED ON CELLULOSE, TEMPO-OXIDIZED CELLULOSE NANOFIBRILS AND CHITOSAN FOR EXTENDING THE SHELF LIFE OF FOOD
No full textSavremena ambalaža za hranu nema više samo pasivnu ulogu u zaštiti i prodaji hrane, nego aktivno menja stanje upakovane hrane da bi se produžio njen rok održivosti. Sa tog aspekta, ambalaža na bazi celuloze, TEMPO oksidisanih celuloznih nanofibrila (TOCN) i hitozana ima veliki potencijal primene. U ovom radu napravljeni su ultra tanki filmovi (debljine ispod 100 nm) na bazi celuloze, TOCN i hitozana kako bi poslužili kao generalni model ambalaže na bazi celuloze, TOCN i hitozana. Na njima je primenom kvarc-kristal mikrovage sa praćenjem disipacije
(QCM-D) ispitano na koji način naslojavanje sa TOCN utiče na sorpciona svojstava ambalaže na bazi celuloze, kao i na kojim pH vrednostima dolazi do veće adsorpcije hitozana na ambalažu na bazi celuloze i TOCN. Bioaktivnost višeslojnih tankih filmova ispita je in vitro u odnosu na Staphylococcus aureus and Escherichia coli. Multifunkcionalna svojstva (visok kapacitet sorpcije vode i antibakterijska svojstava) čine ove filmove na bazi polisaharida pogodnim za izradu ambalaže za hranu.Modern food packaging no longer only plays a passive role in protecting and selling food, but actively changes the state of the packaged food in order to extend its shelf life. From that aspect, packaging based on cellulose, TEMPO-oxidized cellulose nanofibrils (TOCN), and chitosan, has great application potential. In this work, ultra-thin films (thickness below 100 nm) based on cellulose, TOCN, and chitosan were made to serve as a general model for packaging based on cellulose, TOCN, and chitosan. Using a quartz crystal microbalance with dissipation (QCM-D),
it was investigated how TOCN coating affects the water absorbance capacity of cellulose-based ultra-thin films, as well as at which pH values greater chitosan adsorption occurs on ultra-thin films based on cellulose and TOCN. The bio-activity of the multilayered thin films was evaluated in vitro against Staphylococcus aureus and Escherichia coli. The multifunctionality comprising high water absorbance capacity and antimicrobial activity, recommend such polysaccharide-based thin films for food packaging applications
Nanobiocatalyst based on covalent immobilization of proteases onto functionalized nanocellulose for efficient production of sunflower meal protein hydrolysates
No full textThis study aimed to engineer bio-based and environmentally friendly nanobiocatalyst systems using commercially available protease preparations, Alcalase® 2.4L (Alcalase) and Flavourzyme® (Flavourzyme), along with functionalized cellulose nanocrystals (CNC). The study highlights the advantageous properties of the obtained glutaraldehyde-activated amino-modified CNC support (GA-amino-CNC), characterized as nanorods with dimensions ranging between 100 and 800 nm in length and 40–60 nm in width, particularly for protease immobilization. Maximum specific activity of immobilized Alcalase (15 IU/mg of proteins) was achieved at an initial enzyme concentration of 52 mg/g of support after 3 h, with 80% of covalently attached enzyme molecules. In the case of Flavourzyme, maximum exo-hydrolytic activity of 21 L-pNAU/g of support was observed after 20 min, while a higher yield of covalently bound enzyme molecules (53%) detected after 1 h. The covalently bound proteases on glutaraldehyde-activated amino-modified cellulose nanocrystals were evaluated for their efficacy in producing high-quality sunflower-based protein hydrolysates suitable for food and feed applications. Sequential hydrolysis of sunflower meal protein isolate (SMPI) using the developed nanobiocatalysts yielded a maximum hydrolysis degree of 20%. In addition, more than 80% of the initial activity of nanobiocatalysts were retained after 3 reuses, suggesting that these protease nanobiocatalysts have potential application in production of SMP hydrolysates
THE APPLICATION OF NOVEL COMPOUNDS BASED ON STILBAZOLIUM SALTS IN DYE-SENSITIZED SOLAR CELLS
No full textSolarne ćelije aktivirane bojom (DSSC) su privukle pažnju u poslednje dve decenije zbog svoje
potencijalne isplativosti i efikasnosti pretvaranja upadne sunčeve svetlosti u električnu energiju. U
ovom radu, pet novih jedinjenja na bazi stilbazolijum-soli, donor-π-akceptor strukture (D-π-A), je
sintetizovano i okarakterisano za mogućnost primene u DSSC. Zbog svoje kvaternarne strukture,
atom azota u ovim jedinjenjima ispoljava jak elektron-akceptorski karakter koji promoviše
intramolekulski transfer naelektrisanja. Ovo svojstvo je omogućilo primenu stilbazolijum-soli u
brojnim granama industrije i nauke (kao prekursori, intermedijeri, katalizatori, oksidanti, inhibitori
korozije i enzima, agensi za kompleksiranje, jonske tečnosti, katjonski površinski aktivne materije
itd.). Kako bi se stekao bolji uvid u odnos između fizičko-hemijskih i elektronskih karakteristika
sintetizovanih jedinjenja, izvršena je DFT analiza, pri čemu je pokazano da je jedinjenje sa 4-(N,Ndimetilamino)fenil-grupom kao elektron-donorskom ispoljilo najnižu vrednost energije pobuđivanja,
a samim tim i najveću vrednost maksimuma apsorpcije, što je u dobroj korelaciji sa eksperimentalno
dobijenim rezultatima. Sintetizovana jedinjenja su zatim ukapavana u komercijalni tečni elektrolit na
bazi jod/trijodid soli, sa ciljem poboljšanja fotonaponske performanse solarne ćelije sa N719 bojom.
Dobijeni rezultati su pokazali da je dodavanje svih sintetizovanih jedinjenja u komercijalni tečni
elektrolit poboljšalo efikasnost konverzije napravljenih solarnih ćelija u poređenju sa referentnom
solarnom ćelijom u kojoj je korišćen samo tečni elektrolit na bazi jod/trijodid soli. Takođe, pokazano
je da su fotonaponske performanse napravljenih solarnih ćelija zavisile od elektron-donorskog dela
sintetizovanih jedinjenja. Najveća efikasnost fotonaponske konverzije od 4,11% je dobijena za DSSC
sa jedinjenjem koje je u svojoj strukturi sadržalo 4-(N,N-dimetilamino)fenil-grupu kao elektrondonorsku.Dye-sensitized solar cells (DSSCs) have attracted attention over the past two decades due to their potential cost-effectiveness and efficiency in converting incident sunlight into electricity. In this paper, five novel donor-π-acceptor (D-π-A) structured compounds based on stilbazolium salt, were synthesized and characterized for the potential application in DSSC. Due to its quaternary structure, the nitrogen atom in these compounds exhibits a strong electron-acceptor character which promotes intramolecular charge transfer. This property has enabled the application of stilbazolium salts in numerous branches of industry and science (as precursors, intermediates, catalysts, oxidants, corrosion and enzyme inhibitors, complexing agents, ionic liquids, cationic surfactants, etc.). To gain a better insight into the relationship between the physico-chemical and electronic characteristics of the synthesized compounds, a DFT analysis was performed, whereby it was showed that the compound with the 4-(N,N-dimethylamino)phenyl group as an electron donor showed the lowest value of the excitation energy, and therefore the highest value of the absorption maximum, which is in good correlation with the experimentally obtained results. The synthesized compounds were then dropped into a commercial liquid electrolyte based on iodine/triiodide salt, with the aim of improving the photovoltaic performance of the solar cell with N719 dye. The obtained results showed that the addition of all synthesized compounds to the commercial liquid electrolyte improved the conversion efficiency of the fabricated solar cells compared to the reference solar cell in which only iodine/triiodide salt-based liquid electrolyte was utilized. Also, it was shown that the photovoltaic performance of the fabricated solar cells depended on the electron-donor moiety of the synthesized compounds. The highest conversion efficiency of 4.11% was obtained for DSSC with a compound that contained 4-(N,N-dimethylamino)phenyl group as an electron donor
ISOLATION OF DIETARY FIBERS FROM SOY HULL AND INCORPORATION IN NOVEL GLUTEN FREE COOKIES
No full textGluten-free baked products often present quality defects, low nutritional value and low sensorial quality.
The supplementation of non-wheat flour and dough with healthy dietary fibres (DFs) and prebiotic is a
usual practice for increasing the nutritional value of gluten-free products while improving their texture,
shelf-life and mouthfeel. However, the effectiveness of DFs to mimic the properties of gluten to
overcome problems of gluten-free systems or promote health benefits depends not only on extraction
process but also on their source, structural and chemical composition. Pectin and their oligosaccharides
are valuable compounds providing the known associated health benefits.
In this paper, we examined two methods for extracting DFs from soy hulls, which are waste streams
generated during the production of soy proteins. Specifically, these methods include acid extraction
using a 0.5 M HCl solution for 30 min and ultrasonic extraction performed in cycles under the following
conditions: 22-25 kHz, duty cycle 0.67, power 490 W (90%). Extracted DFs was characterized
regarding its galacturonic acid (GalA) content, degree of methoxylation (DM), degree of acetylation
(DA) and functional properties like water (WHC) and oil (OHC) holding capacities, as well as
solubility. Significantly higher yield of DFs was achieved with acid extraction, and the functional
properties of the extracted fibers were satisfactory. Content of GalA amounted 40% (m/m), DM was
determined to be 30% and DA 0.9%. Average MW determined by HPSEC was 1815 kDa, WHC was
amounted to 12 g/g while OHC was 2.44 g/g. Solubility was determined to be 50%.
The obtained fibers were incorporated into rice cookies: a control batch with rice flour and two batches
with 10% (10CDF) and 20% (20CDF) fiber substitution. The addition of pectic fibers resulted in darker,
smaller cookies with decreased hardness (29% for 10CDF and 14% for 20CDF). The cookies also
exhibited better nutritional, textural and sensory properties compared to the control. Physico-chemical
analysis revealed that 10CDF cookies are a "source of dietary fiber" (4.1% fiber) and 20CDF cookies
are "rich in dietary fiber" (7.9% fiber), as per Regulation no. 1924/2006
Regionalni sastanak urednika naučnih časopisa: napori malih izdavača da se održe
No full textAt the end of May 2024, a traditional regional meeting of editors of small scientific journals in engineering disciplines was held at the Faculty of Mechanical Engineering in Belgrade. This year the meeting gathered about 20 editors who discussed novelties, good practices as well as problems in academic publishing. The primary aim of these journals was to support the local scientific community and industry by providing a platform for presenting scientific advances, connecting research and practice, and assisting young scientists in publishing their research results. However, with the widespread adoption of measuring scientific performance by publication and citation statistics, the scientists lost interest in these journals as underrated in researcher evaluation systems. Thus, low quality of received as well as revised manuscripts, low response rates of reviewers, and, consequently, long processing times and high rejection rates are some of the main problems mentioned at the meeting. All these issues are usually managed by editorial offices, which often have neither technical nor human resources for such endeavors. Still, the conclusion of the meeting was that the benefits of small independent scientific journals are significant and worth efforts particularly for providing an alternative to the profit-oriented publishing and promoting societally relevant research and value-based scientific assessments.Krajem maja 2024. godine na Mašinskom fakultetu u Beogradu održan je tradicionalni regionalni skup urednika malih naučnih časopisa iz inženjerskih disciplina. Ove godine skup je okupio oko 20 urednika koji su razgovarali o novinama, dobrim praksama, kao i problemima u akademskom izdavaštvu. Primarni cilj ovih časopisa bio je da podrže lokalnu naučnu zajednicu i industriju pružanjem platforme za predstavljanje naučnih dostignuća, povezivanje istraživanja i prakse i pomoć mladim naučnicima u objavljivanju rezultata svojih istraživanja. Međutim, sa usvajanjem široko rasprostranjenog merenja naučnog učinka putem statistike objavljivanja i broja citata, naučnici u regionu su izgubili interesovanje za ove časopise kao potcenjene u sistemima evaluacije istraživača. Dakle, loš kvalitet primljenih, kao i revidiranih rukopisa, niske stope odgovora recenzenata i, shodno tome, dugo vreme obrade i visoke stope odbijanja radova su neki od glavnih problema pomenutih na sastanku. Sve ove časopise najčešće vode redakcije koje često nemaju ni tehničke ni ljudske resurse za takve poduhvate. Ipak, na sastanku je zaključeno da su prednosti ovakvih malih nezavisnih naučnih časopisa značajne i vredne truda, posebno u pružanju alternative profitno orijentisanom izdavaštvu, kao i promovisanju društveno relevantnih istraživanja i procene naučnih doprinosa zasnovane na vrednostima