Search

Mesoporous bioactive glass nanoparticles (MBGNs) doped with therapeutical ions present multifunctional systems that enable a synergistic outcome through the dual delivery of drugs and ions. The aim of this study was to evaluate influence of co-doping with strontium and magnesium ions (SrMg-MBGNs) on the properties of MBGNs. A modified microemulsion-assisted sol–gel synthesis was used to obtain particles, and their physicochemical properties, bioactivity, and drug-loading/release ability were evaluated. Indirect biological assays using 2D and 3D cell culture models on human bone marrow-derived mesenchymal stem cells (hBM-MSCs) and endothelial EA.hy926 cells, respectively, were used to determine biocompatibility of MBGNs, their influence on alkaline phosphatase (ALP) production, calcium deposition, and cytoskeletal organization. Results showed that Sr,Mg-doping increased pore volume and solubility, and changed the mesoporous structure from worm-like to radial–dendritic, which led to a slightly accelerated drug release compared to pristine MBGNs. Biological assays confirmed that particles are biocompatible, and have ability to slightly induce ALP production and calcium deposition of hBM-MSCs, as well as to significantly improve the proliferation of EA.hy926 compared to biochemical stimulation via vascular endothelial growth factor (VEGF) administration or regular media. Fluorescence staining revealed that SrMg-MBGNs had a similar effect on EA.hy926 cytoskeletal organization to the VEGF group. In conclusion, Sr,Mg-MBGNs might be considered promising biomaterial for biomedical applications.

This study aimed to compare the biological properties of newly synthesized cements based on calcium phosphate with a commercially used cement, mineral trioxide aggregate (MTA). Strontium (Sr)-, Copper (Cu)-, and Zinc (Zn)-doped hydroxyapatite (miHAp) powder was obtained through hydrothermal synthesis and characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD), and energy dispersive X-ray spectrometry (EDX). Calcium phosphate cement (CPC) was produced by mixing miHAp powder with a 20 wt.% citric acid solution, followed by the assessment of its compressive strength, setting time, and in vitro bioactivity. Acetylsalicylic acid (ASA) was added to the CPC, resulting in CPCA. Biological tests were conducted on CPC, CPCA, and MTA. The biocompatibility of the cement extracts was evaluated in vitro using human dental pulp stem cells (hDPSCs) and in vivo using a zebrafish model. Antibiofilm and antimicrobial effect (quantified by CFUs/mL) were assessed against Streptococcus mutans and Lactobacillus rhamnosus. None of the tested materials showed toxicity, while CPCA even increased hDPSCs proliferation. CPCA showed a better safety profile than MTA and CPC, and no toxic or immunomodulatory effects on the zebrafish model. CPCA exhibited similar antibiofilm effects against S. mutans and L. rhamnosus to MTA.

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.

The Ti−45Nb (wt.%) alloy properties were investigated in relation to its potential biomedical use. Laser surface modification was utilized to improve its performance in biological systems. As a result of the laser treatment, (Ti,Nb)O scale was formed and various morphological features appeared on the alloy surface. The electrochemical behavior of Ti−45Nb alloy in simulated body conditions was evaluated and showed that the alloy was highly resistant to corrosion deterioration regardless of additional laser surface modification treatment. Nevertheless, the improved corrosion resistance after laser treatment was evident (the corrosion current density of the alloy before laser irradiation was 2.84×10−8 A/cm2, while that after laser treatment with 5 mJ was 0.65×10−8 A/cm2) and ascribed to the rapid formation of a complex and passivating bi-modal surface oxide layer. Alloy cytotoxicity and effects of the Ti−45Nb alloy laser surface modification on the MRC-5 cell viability, morphology, and proliferation were also investigated. The Ti−45Nb alloy showed no cytotoxic effect. Moreover, cells showed improved viability and adherence to the alloy surface after the laser irradiation treatment. The highest average cell viability of 115.37% was attained for the alloy laser-irradiated with 15 mJ. Results showed that the laser surface modification can be successfully utilized to significantly improve alloy performance in a biological environment.

Primary implant stability after implantation is in relation with its good mechanical contact with the touching tissue. Adequate integration of the implant with the bone tissue is necessary to provide safety and efficiency of the implant over its life. Generally, two surface properties are the most important facts for tissue response to the implant: the surface topography and chemical composition. Compared to a smooth implant surface, a controlled rough surface provides more surface area for integration with the surrounding tissues and allows successful implant ingrowth into the tissues. It was found that the nanostructured modification of the titanium surface on the level of nano-sized pores influences the adhesion, spreading and growing of osteoblastic cells. There are many methods for nanostructure modification of biomedical alloy surfaces, but one of the common techniques is electrochemical anodization (anodic oxidation). Electrochemical anodization is a method that leads to the creation of a nanotubular oxide film on the material surface. The advantage of anodic oxidation is the possibility of controlling the nanostructured morphology of the surface and dimensions of nanotubes, such as diameter, length, wall thickness and shape of nanotubes through variation of the solution, pH value, potential or duration of anodic oxidation. Surface modification of Ti-13Nb-13Zr alloy in a coarse-grained (as received) and ultrafine-grained state induced by high pressure torsion was conducted using an electrochemical anodization process in a 1 M H3PO4 + NaF electrolyte, for 30, 60, 90 and 120 minutes. Scanning electron microscopy (SEM) was used to analyze the morphology, while atomic force microscopy (AFM) was used to characterize the topography of the modified surface. The results showed that a homogenous nanotubular oxide film consisting of nanotubes could be obtained using the electrochemical anodization treatment, while the roughness of the nanostructured surface increased c

This study aimed to (1) comparatively analyze properties of Sr- and Mg-substituted hydroxyapatite (HAP)-based dental inserts; (2) evaluate insert bonding to restorative materials, and (3) evaluate the effect of doped HAP inserts on fracture resistance (FR) of human molars with large occlusal restorations. By ion-doping with Sr or Mg, 3 insert types were obtained and characterized using XRD, SEM, Vickers hardness and fracture toughness. Shear bond strength (SBS) was determined between acid etched or unetched inserts and following materials: Maxcem cement (Kerr); Filtek Z250 (3M) bonded with Single Bond Universal (SBU; 3M) or Clearfil Universal (Cf; Kuraray). Modified Class I cavities were prepared in 16 intact molars and restored using insert + composite or composite only (control) (n = 8/group). FR of restored molars was determined by static load until fracture upon thermal cycling. Fracture toughness was similar between Sr/Mg-doped inserts (0.94–1.04 MPam 1/2 p = .429). Mg-doped inserts showed greater hardness (range 4.78–5.15 GPa) than Sr6 inserts (3.74 ± 0.31 GPa; p < .05). SBS for SBU and Cf adhesives (range 7.19–15.93 MPa) was higher than for Maxcem (range 3.07–5.95 MPa) (p < .05). There was no significant difference in FR between molars restored with insert-containing and control restorations (3.00 ± 0.30 kN and 3.22 ± 0.42 kN, respectively; p > .05). HAP-based inserts doped with Mg/Sr had different composition and mechanical properties. Adhesive bonding to inserts resulted in greater bond strength than cementation, which may be improved by insert acid-etching. Ion-doped HAP inserts did not affect FR of restored molars. In conclusion, HAP-based dental inserts may potentially replace dentin in large cavities, without affecting fracture resistance of restored teeth.

Objectives: To assess and compare the cell viability and ion release profiles of two conventional glass ionomer cements (GICs), Fuji IX and Ketac Molar EasyMix, modified with TiO2 and Mg-doped-HAp nanoparticles (NPs). Methods: TiO2 NPs, synthesized via a sol–gel method, and Mg-doped hydroxyapatite, synthesized via a hydrothermal process, were incorporated into GICs at a concentration of 5 wt.%. The biocompatibility of prepared materials was assessed by evaluating their effects on the viability of dental pulp stem cells (DPSCs), together with monitoring ion release profiles. Statistical analysis was performed using One-way analysis of variance, with significance level p < 0.05. Results: The addition of NPs did not significantly affect the biocompatibility of GICs, as evidenced by comparable decreased levels in cell viability to their original formulations. Distinct variations in cell viability were observed among Fuji IX and Ketac Molar, including their respective modifications. FUJI IX and its modification with TiO2 exhibited moderate decrease in cell viability, while other groups exhibited severe negative effects. While slight differences in ion release profiles were observed among the groups, significant variations compared to original cements were not achieved. Fluoride release exhibited an initial “burst release” within the initial 24 h in all samples, stabilizing over subsequent days. Conclusions: The addition of NPs did not compromise biocompatibility, nor anticariogenic potential of tested GICs. However, observed differences among FUJI IX and Ketac Molar, including their respective modifications, as well as induced low viability of DPSC by all tested groups, suggest the need for careful consideration of cement composition in their biological assessments. Clinical significance: The findings contribute to understanding the complex interaction between NPs and GIC matrices. However, the results should be interpreted recognizing the inherent limitations associated

Bioactive materials for the repairand regeneration of human bone tissue, as well as for the restoration of teeth, are the focus of numerous studies in the field of biomaterials.Orthopaedic surgeons anticipate that bioactive materialshave the potential to facilitate the formation of new apatite-like crystals upon contact with body fluids, promoting the development of new bone tissue under in vivoconditions. On the other hand, dentists expect that bioactive materials have the potential for remineralization of partially demineralized enamel and dentin. In the preceding years, the Bioceramic Materials Group, founded within the Department of Inorganic Chemical Technology at the Faculty of Technology and Metallurgy, University of Belgrade (FTM-UB), conducted extensive research on the advancement of bioactive and biocompatible materials with adequate mechanical properties, designed for applicationin dentistry, orthopaedics, maxillofacial surgery, and also bone tissue engineering(BTE).

INTRODUCTION: 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, enha

The combination of hydroxyapatite with biopolymers like zein holds great promise for enhancing the properties of bone implants. Hydroxyapatite provides structural similarity with bone minerals, facilitating integration with natural bone tissue, while zein adds further benefits such as biodegradability, biocompatibility, and even potential antibacterial activity. By incorporating zein onto the surface of hydroxyapatite coatings, the implant becomes more compatible with the body's tissues, reducing the risk of rejection or adverse reactions. Additionally, the controlled biodegradability of zein allows for gradual replacement by natural bone tissue over time, promoting long-term stability and integration of the implant. This paper presents an investigation into the biocompatibility of zein/titanium dioxide (zein/TiO2), hydroxyapatite/zein/titanium dioxide (HAp/zein/TiO2) and strontium-doped hydroxyapatite/zein/titanium dioxide (Sr-HAp/zein/TiO2) composite coatings which obtained by in-situ anodization/anaphoretic deposition process. The biocompatibility of all prepared coatings was assessed by measuring cell viability through the MTT test using two different fibroblast cell lines: L929 and MRC-5. The results indicated an increase in the number of viable cells in all tested samples. The highest percentage of survival of healthy L929 and MRC-5 cells was observed with the zein/TiO2 coating. This suggests that zein is not only non-cytotoxic but also enhances cell proliferation, differentiation, and cell viability when present in the coatings. The morphology and adhesion of cells on the surface were analysed using SEM. Biocompatibility testing confirmed that the coatings are safe for use in both orthopedic and dental applications.

INTRODUCTION: Hydroxyapatite, the main inorganic component of human bone, is a widely used bioceramic for bone implant coatings due to its chemical and structural similarity with bone minerals and approved biocompatibility. Nowadays, the surface properties of implants are also modified by the addition of different biopolymers. Features such as biocompatibility, tuned biodegradability, and non-cytotoxicity make these materials excellent candidates for these applications. Zein is one of the natural polymers that has gained great interest for biomedical applications due to its natural renewable resource, biodegradability, biocompatibility and potential antibacterial activity. EXPERIMENTAL: In this study, zein/titanium dioxide (zein/TiO2), hydroxyapatite/zein/titanium dioxide (HAp/zein/TiO2) and strontium-doped hydroxyapatite/zein/titanium dioxide (Sr-HAp/zein/TiO2) coatings were obtained on a titanium substrate by in situ anodization/anaphoretic deposition method at a constant voltage of 60 V and deposition time of 1 min. For the fabrication of HAp/zein/TiO2 and Sr-HAp/zein/TiO2 composite coatings, HAp and Sr-HAp nano-sized powders obtained by a modified chemical precipitation method were used. The microstructure and morphology of all coatings were characterized by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR) and scanning electron microscopy (SEM). Adhesion strength was measured according to the ASTM D3359-02 standard. Morphology and cell adhesion were analyzed by SEM. RESULTS AND DISCUSSION: The advantage of this methodological approach compared to cataphoretic deposition is reflected in the simultaneous performance of several processes. The first is the anodization of the substrate surface, whereby a passive oxide layer (TiO2) is formed on the surface, which changes the structure and increases the surface roughness in a controlled manner. Another parallel process is the deposition of the HAp based coatings on the substrate. This way of coa

Limited bone bank capacity and risk of infection are some of the main drawbacks of autologous and allogenic grafts, giving rise to synthetic materials for bone tissue implants. The aim of this study was to process and evaluate the mechanical properties and bioactivity of magnesium and strontium doped hydroxyapatite (HAp) scaffolds and investigate the effect of adding zirconium oxide and gelatine coating the scaffolds. Doped nanosized hydroxyapatite powder was synthesized by the hydrothermal method and the scaffolds were made by the foam replica technique and sintered at different temperatures. Yttria-stabilized zirconium oxide (YSZ), synthesized by plasma technology, was used as reinforcement of calcium phosphate scaffolds. Element analysis, phase composition, morphology of the powders and microstructure of the scaffolds were investigated, as well as the compressive strength of the coated and uncoated scaffolds and bioactivity in simulated body fluid (SBF). A microporous structure was achieved with interconnected pores and bioactivity in SBF was confirmed in all cases. The best mechanical properties were given by the coated composite HAp/YSZ scaffolds, withstanding average stresses of over 1019 kPa. These results encourage the idea of use of these scaffolds in bone regenerative therapy and bone tissue engineering.

Limited bone bank capacity and risk of infection are some of the main drawbacks of autologous and allogenic grafts, giving rise to synthetic materials for bone tissue implants. The aim of this study was to process and evaluate the mechanical properties and bioactivity of magnesium and strontium doped hydroxyapatite (HAp) scaffolds and investigate the effect of adding zirconium oxide and gelatine coating the scaffolds. Doped nanosized hydroxyapatite powder was synthesized by the hydrothermal method and the scaffolds were made by the foam replica technique and sintered at different temperatures. Yttria-stabilized zirconium oxide (YSZ), synthesized by plasma technology, was used as reinforcement of calcium phosphate scaffolds. Element analysis, phase composition, morphology of the powders and microstructure of the scaffolds were investigated, as well as the compressive strength of the coated and uncoated scaffolds and bioactivity in simulated body fluid (SBF). A microporous structure was achieved with interconnected pores and bioactivity in SBF was confirmed in all cases. The best mechanical properties were given by the coated composite HAp/YSZ scaffolds, withstanding average stresses of over 1019 kPa. These results encourage the idea of use of these scaffolds in bone regenerative therapy and bone tissue engineering.

Hydrogels are attractive materials for drug delivery applications due to biocompatible, porous structure with the possibility to load and deliver drugs in a controllable manner. In this paper, poly(methacrylic acid) (PMAA) hydrogels are described, which are synthesized by free-radical polymerization, using poly(ethylene glycol) diacrylate (PEGDA) as a crosslinker. Influence of the PEGDA content on hydrogel properties was investigated and compared to commonly used crosslinker - N,N’-methylenebisacrylamide (MBA). The increasing concentration of crosslinkers led to a higher degree of crosslinking, which was demonstrated by a higher degree of conversion, lower swelling capacity, and improved thermal stability and mechanical properties. Also, the PEGDA-crosslinked hydrogels demonstrated a higher degree of crosslinking than the corresponding MBA-crosslinked hydrogels. Potential application of the synthesized hydrogels for controlled drug delivery was investigated by using two model drugs - oxaprozin and ciprofloxacin. In vitro drug release tests indicated that the interactions between drug, polymer and medium have a key influence on the drug release behavior, rather than the swelling rate. Drug release tests in simulated gastrointestinal conditions indicated that PEGDA-crosslinked PMAA hydrogels are suitable for colon-targeted delivery of oxaprozin., Zbog svoje biokompatibilne, visoko-porozne strukture i mogućnosti da nose i kontrolisano otpuštaju lekove, hidrogelovi su našli široku primenu u biomedicini. U ovom radu, hidrogelovi na bazi poli(metakrilne kiseline) (PMK), umreženi pomoću poli(etilen-glikol) diakrilata (PEGDA), sintetisani su metodom toplotno-indukovane slobodno-radikalske polimerizacije. Ispitan je uticaj sadržaja PEGDA na svojstva hidrogelova i upoređen sa uticajem najčešće korišćenog umreživača – N,N' – metilenbisakrilamida (MBA). Povećanje količine oba umreživača dovelo je do većeg stepena umreženja, što je bilo manifestovano povećanjem stepena konverzije monomera, smanjenjem ravnotežnog stepena bubrenja i poboljšanim toplotnim i mehaničkim svojstvima. Takođe, hidrogelovi umreženi pomoću PEGDA pokazali su veći stepen umreženja u odnosu na odgovarajuće hidrogelove umrežene pomoću MBA. Mogućnost primene dobijenih hidrogelova za kontrolisano otpuštanje lekova, ispitivano je korišćenjem dva leka – oksaprozina i ciprofloksacina. In vitro testovi otpuštanja pokazali su da presudan uticaj na kinetiku otpuštanja imaju međusobne interakcije između leka, hidrogela i medijuma, a ne stepen i brzina bubrenja hidrogela. Prema tome, otpuštanje ciprofloksacina je bilo intenzivnije u kiseloj sredini, a oksaprozina u baznoj. Otpuštanje u simuliranim gastrointestinalnim uslovima pokazalo je da su PEGDA-umreženi hidrogelovi pogodni za kontrolisano otpuštanje oksaprozina u debelo crevo.

The main drawback of resin-based composites (RBCs) widely used in restorative dentistry presents their volumetric shrinkage during the polymerization that can lead to clinical failures of restorations such asmarginal gap formation, bacterial microleakage, fractures, and postoperative sensitivity. To address this problem, sintered hydroxyapatite based dental inserts were introduced in the central part of molar teethrestoration, due to chemical and structural similarities with inorganic part of teeth. The fabrication of bioceramic dental inserts based on HAP doped with Sr and/or Mg ions presents a way to obtain a dentin substitute that has even greater resemblance to the biological apatite in dentin. However, ion-substitutions arise lattice strain that can have a signifi cant impact on phase composition and properties of apatite materials, especially upon thermal treatment, which could be determining for their further application. The aims of this study were to comparatively analyze physico-chemical and mechanical properties of the Sr- or Mg-, and Sr+Mg substituted HAP based dental inserts; and evaluate their possible application as dentinsubstitutes. Mono (5 mol. % Sr or Mg ions) and binary- (3 mol.% Sr and 3 mol.% Mg ions) doped HAP nanoparticles were hydrothermally obtained, isostatically pressed into compacts and eventually sintered at 1200°C to obtain dental inserts. The inserts are meant to be adhered to the cavity walls as well as topped with resin composite for sealing and esthetic purposes. Bonding ability of obtained inserts with different commercialrestorative materials, as well as fracture resistance of human molars restored with doped HAP inserts was investigated. Ion doping was found to infl uence phase compositions of sintered inserts, leading to different mechanical properties and etching behavior of inserts. All inserts showed fracture toughness and bonding ability torestorative materials similar to dentin, while the highest bond strength was obtained

Natural zeolite is a good sorbent for many cations due to its specific porous structure. The degree of sorption efficiency depends on the cation type and the availability of exchange positions in the zeolite lattice. The aim of this work is to examine the synthesis possibility of a new adsorbent based on natural zeolite and hydroxyapatite. The adsorbent was prepared mechanochemically by using clinoptilolite-rich zeolite tuff from the Slanci deposit (Serbia) and hydroxyapatite obtained by the hydrothermal process. The milling process was performed in a ball mill and optimized regarding contact time and milling speed. For the synthesis of zeolite/hydroxyapatite adsorbent (ZHAp), optimal values for these two parameters were 10 min and 250 rpm, respectively. The resulting sample ZHAp was characterized by X-ray powder diffraction, thermal analysis and scanning electron microscopy. Diffraction analysis of the ZHAp confirmed the presence of the most abundant mineral in zeolite tuff - clinoptilolite and hydroxyapatite. Needle-like crystals of hydroxyapatite on the clinoptilolite surface are observed in SEM images. Zeolite/hydroxyapatite sample is thermally stable at 800 °C. Adsorption properties of ZHAp were examined for nickel and chromium ions, towards which natural zeolite shows a low affinity. The presence of hydroxyapatite on the zeolite surface led to an increase in the adsorption capacity more than two times for both tested ions compared to the initial zeolite tuff.

The coarse-grained (CG) and ultrafine-grained (UFG) Ti-13Nb-13Zr alloy (TNZ) were used as tested materials in this study. UFG alloy was obtained using a high-pressure torsion process (HPT) at room temperature, with 5 rotations, and with 4.1 GPa pressure. After that, the surface was modified using electrochemical anodization in the 1M H3PO4 + NaF electrolyte, for 60 and 90 minutes. Scanning electron microscopy (SEM) was used to characterize the morphology of the modified surface after electrochemical anodization. In order to determine whether the electrochemical anodization leads to obtaining the surface modulus of elasticity values close to the values characteristic of the human bones, a nanoindentation test was done. The nanoindentation test was performed on the device called nanoindenter G200, Agilent Technologies, where a diamond tip of the Berkovich type shaped as a three-sided pyramid was used as an indenter. Control of the nanoindentation test was done by nanoindentation depth, where for non-anodized materials a depth of 2000 nm was used, while for anodized materials a minimum value of 10% of the thickness of the formed nanostructured oxide layer was used. Biocompatibility of the tested titanium alloy was estimated by the tetrazolium salt colorimetric test (MTT test) using mouse fibroblasts (L-929) and human lung fibroblasts (MRC-5). The cell adhesion on the alloy surface was analyzed using SEM. Electrochemical anodization has led to the formation of the nanostructured oxide layer on the titanium alloy surface. The obtained results show the existence of the influence of anodizing time on the nanostructured oxide layer morphology. Characterization of the titanium alloy surface using nanoindentation showed a decrease in the values of modulus of elasticity for an alloy with a nanostructured oxide layer, which is close to the values of bone tissue in the human body. The results of the MTT test showed that the titanium alloys before and after electrochemical anodiz

Corn is one of the world´s most commonly cultivated crops.A major part of the plant remaining after harvesting is the corn stalk.This corn residueis rich in carbohydrates and could be suitable for the fermentative production of numerous value-added products. The corn stalk’s complex structure, recalcitrance deriving from lignin, and high crystallinity and polymerization degree of cellulose prevent conventional pretreatment techniques to separate it efficiently into elementary fractions. Therefore, it is usually processed by burning directly on the ground or landfilling.It seldom can be used for composting or combusted for heat generation. In this study, different advanced oxidation processes were used for the treatment of corn stalks to enable more sustainable valorization of biomass by enzymatic hydrolysis. The effects of non-thermal plasma treatment, treatment with Fenton reagent, and combined non-thermal plasma/Fenton treatment on lignocellulose degradation and biomass digestibility were monitored. Treatment efficacy in terms of degradation was assessed by determininglignincontent. Structural and textural properties of treated biomass were analyzed using FTIR analysis and mercury intrusion porosimetry (MIP).The carbohydrate digestibility estimation was based on hexose and pentose content in hydrolyzed samples. Applied treatments showed success in breaking complex lignocellulose structures. The delignification rates for the non-thermal plasma treated sample, thesample treated only with the Fenton reagent, and the combined non-thermal plasma/Fenton treated sample were 19%, 28.7%, and 53%, respectively. Selectivity towards lignin increased with prolonging the non-thermal plasma treatmentorthe addition of the Fenton reagent.To achieve a delignification rateof 53% by using only non-thermal plasma, treatment should last at least 60 minutes. When the Fenton reagent is added, the same result is obtained with a halved duration of the plasma treatment. Under these conditio

This study focused on investigating the effects of voltage and deposition time on the formation and morphology of hydroxyapatite/titanium oxide coatings, which were obtained using an in-situ synthesis process. The coatings were prepared under various voltage conditions and deposition times to analyze their characteristics. To evaluate the morphology of the coatings, optical microscopy and field emission scanning electron microscopy (FE-SEM) techniques were employed. Additionally, Fourier transform infrared spectroscopy (FTIR) was utilized to confirm the presence of hydroxyapatite coatings on the substrate. The results revealed that an increase in voltage led to a more uniform coating. The voltage parameter had a significant impact on the morphology of the initial hydroxyapatite powder, causing the agglomerates to disperse and resulting in smaller particle sizes within the coating. Furthermore, the FTIR analysis provided solid evidence of the presence of hydroxyapatite within the obtained coatings. These findings emphasize the importance of voltage control and deposition time in the in-situ synthesis process for achieving desirable hydroxyapatite/titanium oxide coatings. Understanding the influence of these parameters on coating formation and morphology can contribute to the development of improved techniques for biomedical applications, such as enhanced osseointegration in orthopedic and dental implants.

The silver and gold L-methionine capped nanoparticles (Ag and Au @LM NPs) were analyzed as prospective acetylcholinesterase (AChE) inhibitors to test their potential in the treatment of cognitive impairment in depression and Alzheimer's disease. The stability of NPs, and their ability to inhibit AChE were studied by UV-Vis and FTIR spectrophotometry. At the same time, TEM and SEM measurements, DLS, and zeta potential measurements were employed in the structural characterization of NPs. Nearly spherical, negatively charged Ag and Au @LM NPs, with 17 nm and 31 nm in diameter, respectively, showed moderate inhibitory potential toward AChE in the given frame of investigated concentrations. For both NPs IC50 is not reached. Furthermore, the adsorption of enzyme molecules on the surface of Ag and Au @LM NPs was demonstrated. Hence, our assumption is that inhibition of AChE is caused by blockage of the enzyme‘s active site due to the steric hindrance of NPs.

Kaolinite/illite (KUb) and sepiolite (SEP) clays were used to study Cr(III) adsorption removal from aqueous solutions so that they could be utilized after saturation for ceramic manufacturing. SEP had a larger specific surface area and a higher PZC than KUb. The removal of Cr(III) was evaluated using a batch equilibration procedure at pHi = 4 and pHi = 6. Fast removal kinetics were observed for both clays. Maximum removal capacity was determined by changing the concentration of Cr(III) while keeping the concentration of clay constant and by altering the amount of clay while keeping the concentration of Cr(III) constant. In all situations, SEP had greater capacity than KUb, and capacity was greater for both clays at higher pHi. Not only did the pHi impact the removal capacity and efficiency, but so did the pH during adsorption and the initial concentration of Cr(III). Because of the higher PZC, the pHf for SEP was higher for the same pHi. The higher the pH and Cr(III) concentration, the higher the probability of Cr(OH)3 precipitation and the higher the removal capacity. Dried saturated clays were uniaxially pressed and sintered at 1000 °C for 2 h. The densities of the sintered materials were nearly identical to those of pure clay-based materials, but the compressive strengths were higher, which is significant for the use of saturated clays as raw materials in ceramic manufacturing. Leaching of Cr from SEP-based material was significantly higher than from KUb-based material probably due to the presence of CaCO3 in the SEP.

Tehničko rešenje se odnosi na unapređenje postupka prečišćavanja otpadnih voda koje sadrže trovalentni hrom, kao što su otpadne vode iz površinske zaštite metala, štavljenja kože, zaštite drvenih proizvoda i dr. U konvencionalnim postupcima joni trovalentnog hroma se talože u obliku Cr(OH)3, čime nastaje talog kao sekundarni opasni otpad koji se uglavnom odlaže na deponije, što dovodi do dodatnih troškova i negativnog uticaja na životnu sredinu. U ovom tehničkom rešenju joni trovalentnog hroma se uklanjaju iz vode adsorpcijom na jeftinim glinama iz lokalnih ležišta, jednoj kaolinitsko-ilitskog tipa i jednoj na bazi sepiolita, koje su komercijalno dostupne kao sirovine za proizvodnju tradicionalne keramike. Utvrđen je adsorpcioni kapacitet ovih glina, pri različitim pH vrednostima, variranjem početne koncentracije jona hroma pri konstantnoj koncentraciji adsorbenta, kao i variranjem koncentracije adsorbenta pri konstantnoj koncentraciji jona hroma, u cilju optimizacije procesa prečišćavanja. Imajući u vidu da regeneracijom zasićenih adsorbenata nastaju nove otpadne vode, ovim tehničkim rešenjem je predviđeno da se zasićeni adsorbenti koriste kao sirovine za proizvodnju keramike umesto čistih glinenih minerala. Određivanje pritisne čvrstoće sinterovanih materijala dobijenih od zasićenih adsorbenata je pokazalo da adsorbovani joni hroma ne pogoršavaju mehanička svojstva u poređenju sa materijalima koji su dobijeni od čistih glina, već naprotiv dovode do povećanja pritisne čvrstoće i to u većoj meri u slučaju materijala na bazi sepiolitske gline, čiji je kapacitet adsorpcije veći. Ispitivanja izluživanja hroma iz sinterovanih materijala na bazi zasićenih adsorbenata su pokazala da je izluživanje u slučaju materijala na bazi sepiolitske gline veće od vrednosti koja je definisana odgovarajućim standardom, verovatno zbog prisustva kalcijum-karbonata kao primese ove gline. Ovaj problem se može prevazići povišenjem temperature sinterovanja. Hrom je efikasno imobilisan u mate

Immobilizing antifungal polyenes such as nystatin (Nys) and amphotericin B (AmB) into biodegradable formulations is advantageous compared to free drug administration providing sustained release, reduced dosing due to localized targeting and overall reduced systemic drug toxicity. In this study, we encapsulated Nys and AmB in medium chain length polyhydroxyalkanoates (mcl-PHA) microspheres (7–8 µm in diameter). The obtained formulations have been validated for antifungal activity in vitro against a panel of pathogenic fungi including species of Candida, Aspergillus, Microsporum and Trichophyton genera and toxicity and efficacy in vivo using the zebrafish model of disseminated candidiasis. While free polyenes, especially AmB, were highly toxic to zebrafish embryos at the effective (MIC) doses, after their loading into mcl-PHA microspheres, inner organ toxicity and teratogenicity associated with both drugs were not observed, even at 100 × MIC doses. The obtained mcl-PHA/polyene formulations have successfully eradicated C. albicans infection and showed an improved therapeutic profile in zebrafish by enhancing infected embryos survival. This approach is contributing to the antifungal arsenal as polyenes, although the first broad-spectrum antifungals on the market are still the gold standard for treatment of fungal infections.

Hazelnut shell ash was investigated as a new base catalyst for the transesterification of used cooking sunflower oil to biodiesel. To understand its catalytic properties, the prepared ash was characterized by EDX, XRD, TGA/DTA, Hg porosimetry, N-2 physisorption, FE-SEM, and basic strength measurements. The effects of the catalyst loading in the range of 1-5% of the oil weight and the methanol-to-oil molar ratio of 6:1-18:1 on the kinetics of the fatty acid methyl esters synthesis were established. Moreover, the leaching and reusability of the catalyst were assessed. The obtained results revealed that hazelnut shell ash was mostly composed of K, Ca, and Mg. The highest ester content (98%) was achieved at the catalyst loading of 5%, the methanol-to-oil molar ratio of 12:1, and the reaction time of 10 min. The contribution of homogeneous catalysis because of the catalyst leaching was confirmed but did not determine the overall reaction rate. The catalyst can be reused after the recalcination at 800 degrees C for 2 h achieving the high methyl esters content (>96%) in 30 min after three subsequent runs. The overall reaction followed the pseudo-first-order kinetics with respect to triacylglycerols. A linear relationship between the apparent reaction rate constant and the catalyst loading and the methanol-to-oil molar ratio was determined. The determined value of the reaction rate constant was 0.0576 dm(6)/(min.mol(2)).

Hydrogels are promising materials for biomedical applications due to highly hydrated, porous, permeable structure with possibility to accommodate living cells, drugs, or bioactive factors. In this paper, we reported poly(methacrylic acid) (PMAA)/gelatin IPN hydrogels, synthesized by free-radical polymerization, with adjustable mechanical, structural, physicochemical, and biological characteristics. The influence of methacrylic acid (MAA), gelatin, and cross-linker in the precursor solution on hydrogels properties was investigated. The increasing concentration of MAA, gelatin, and cross-linker led to better mechanical properties, lower porosity, and water content. The compressive mechanical properties of hydrogels were significantly better in comparison to a single-network PMAA hydrogel, while the obtained compressive strength values up to 16 MPa were comparable with tough hydrogels. The increasing concentration of MAA and cross-linker reduced fatigue resistance and degradability, while the increase in gelatin content acted in the opposite way. Swelling tests in different pH conditions demonstrated strong pH-sensibility of the hydrogels, which was more pronounced as MAA concentration was higher, and gelatin and cross-linker concentrations were lower. In addition, the hydrogels strongly promoted the proliferation of human periodontal ligament stem cells and MRC-5 cells as assayed by MTT assay.

Hazelnut shell ash was investigated as a new base catalyst for the transesterification of used cooking sunflower oil to biodiesel. To understand its catalytic properties, the prepared ash was characterized by EDX, XRD, TGA/DTA, Hg porosimetry, N2 physisorption, FE-SEM, and basic strength measurements. The effects of the catalyst loading in the range of 1–5% of the oil weight and the methanol-to-oil molar ratio of 6:1–18:1 on the kinetics of the fatty acid methyl esters synthesis were established. Moreover, the leaching and reusability of the catalyst were assessed. The obtained results revealed that hazelnut shell ash was mostly composed of K, Ca, and Mg. The highest ester content (98%) was achieved at the catalyst loading of 5%, the methanol-to-oil molar ratio of 12:1, and the reaction time of 10 min. The contribution of homogeneous catalysis because of the catalyst leaching was confirmed but did not determine the overall reaction rate. The catalyst can be reused after the recalcination at 800 °C for 2 h achieving the high methyl esters content (>96%) in 30 min after three subsequent runs. The overall reaction followed the pseudo-first-order kinetics with respect to triacylglycerols. A linear relationship between the apparent reaction rate constant and the catalyst loading and the methanol-to-oil molar ratio was determined. The determined value of the reaction rate constant was 0.0576 dm6/(min•mol2).

Opisan je nov sastav nanočestičnog mezoporoznog bioaktivnog stakla dopiranog terapeutskim jonima stroncijuma i magnezijuma velike specifične površine i dimenzija mezopora pogodnih za primenu u medicini i stomatologiji za reparaciju i regeneraciju kostiju i zuba, kao i kod zarastanja rana. Opisan je i postupak za dobijanje ovakvog nanočestičnog mezoporoznog bioaktivnog stakla bez primene postupka mlevenja. Navedena je i moguća primena ovako dobijenog nanočestičnog mezoporoznog bioaktivnog stakla u vidu čestica punioca, cementa, prevlaka kao i sinterovanih gustih i poroznih formi., A novel composition of the nanosized mesoporous bioactive glass doped with strontium and magnesium therapeutic ions, having a large specific surface area and pore size suitable for application in medicine and dentistry for repair and regeneration of bones and teeth, as well as in wound healing, applications. Its manufacturing method without applying milling is also described. A possible application of the nanosized mesoporous bioactive glass obtained by this method in the form of particulate fillers, cements, and coatings, as well as sintered dense and porous forms are also described.