Reka Barabas | UBB - Academia.edu (original) (raw)

Papers by Reka Barabas

Biotechnology and Bioprocess Engineering, Sep 1, 2019

Customized medical implants obtained by selective laser melting have an important applicability d... more Customized medical implants obtained by selective laser melting have an important applicability due the accurate architecture which promotes the osteointegration, osteoconduction, and osteoinduction. This study assessed the in vitro effect of titanium scaffolds, both pure and covered with a layer of hydroxyapatite, on mesenchymal stem cells harvested from various oral tissues. Eight titanium implants were manufactured by selective laser melting, obtaining a porosity of 63.4% and a pore size of 600 µm. Four matrices were covered with nano-hydroxyapatite. Four lines of mesenchymal stem cells isolated from the apical papilla, the dental pulp, the inter-radicular bone, and the tuberosity bone were seeded on the implants. The cells' proliferation, viability, and differentiation into the osteoblastic lineage were assessed after 18 days, using light microscopy and fluorescence. Our results indicated that the titanium matrices did not exert cytotoxic effect. The cells seeded on titanium matrices conditioned with nanohydroxyapatite had a slightly higher proliferation rate. The stem cells isolated from the inter-radicular bone had the most intense proliferation and differentiation towards the osteoblastic lineage showing a nodular architecture. In conclusion, the oral mesenchymal stem cells have the potential to promote and improve bone regeneration when associated with the titanium scaffolds manufactured by selective laser melting, either non-coated or coated with hydroxyapatite. These findings open new perspectives for the bone reconstruction in the oral and maxillofacial surgery field.

Studia Universitatis Babes-bolyai Chemia, Mar 31, 2021

JUDITH-HAJNAL BARTHA-VARI a , RENÁTA ELEKES-DARABONT a , LAURA-EDIT BARABÁS a , RÉKA BARABÁS a, *... more JUDITH-HAJNAL BARTHA-VARI a , RENÁTA ELEKES-DARABONT a , LAURA-EDIT BARABÁS a , RÉKA BARABÁS a, * ABSTRACT. A new and efficient immobilization method of phenylalanine ammonia-lyase was obtained using hydroxyapatite (HAP) and hydroxyapatitecarbon nanotube, gelatin and chitosan-composites (HAP-CNT, HAP-GEL and HAP-CS) as support material. HAP and HAP composites were characterized by transmission electron microscopy (TEM), laser diffraction particle size analyzer and XRD measurements. The obtained nanobioconjugates were tested in the ammonia elimination reactions from L-phenylalanine (L-1). The reusability and the time-course profile of the immobilized enzyme preparation was also tested. While the biocatalyst obtained by using HAP-CS-15 as support material provided the highest conversion rate in the ammonia elimination reaction from L-1 (98,1% compared to 98,5% obtained using the non-immobilized enzyme), the most stable biocatalyst proved to be HAP-PAL, which maintained more than 80% of its initial activity even after 5 cycles of reuse.

Materials Chemistry and Physics, Aug 1, 2023

Arabian Journal for Science and Engineering, 2019

Hydroxyapatite (HAP), the main mineral component of bone and tooth enamel, has become an importan... more Hydroxyapatite (HAP), the main mineral component of bone and tooth enamel, has become an important biomaterial in orthopedic and dental applications. However, its low fracture toughness, poor tensile strength and wear resistance make it not suitable to be used in bone tissue engineering applications, the improvement of mechanical properties of HAP using different additives being still a great challenge. Nowadays, the most used additives for reinforcement are graphene oxide (GO) and single-or multi-walled carbon nanotubes (MWCNTs). The present study reports their successful incorporation of MWCNTs and GO (0.5, 1.0 and 2.0 wt%) into the HAP matrix. The prepared HAP-based nanocomposites (NCs) were characterized by X-ray diffraction, laser diffraction, scanning and transmission electron microscopy, thermal analysis and Raman spectroscopy. Moreover, the UV-Vis spectroscopy was used to investigate the desorption properties of obtained NCs by using ibuprofen, one of the most common prescribed analgesic nonsteroidal anti-inflammatory drugs. It was found that CNTs addition does not have a major influence on desorption efficiency, while the addition of GO evidenced an increase in desorption efficiency over time for all the studied NCs.

Journal of Materials Science: Materials in Medicine, 2019

The aim of this study was to assess the osseointegration of two series of titanium (Ti) scaffolds... more The aim of this study was to assess the osseointegration of two series of titanium (Ti) scaffolds with 0.8 and 1 mm cell size obtained by Selective Laser Melting (SLM) technique. One of the series had the Ti surface unmodified, while the other had the Ti surface coated with silicon-substituted nano-hydroxyapatite (nano-HapSi). The scaffolds were implanted in the femur bone defects of 6 White Californian male rabbits: three animals were implanted with 0.8 mm cell size scaffolds and three animals with 1 mm cell size scaffolds, respectively. The bone fragments and scaffolds harvested at 2, 4 and 6 months were histologically analyzed using conventional light microscopy (LM) and scanning electron microscopy (SEM) for the qualitative evaluation of the bone tissue formed in contact with the scaffold. Both LM and SEM images indicated a better osseointegration for nano-HapSi coated Ti scaffolds. LM revealed that the compact bone formed in the proximity of nano-HapSi-coated scaffolds was better organized than spongy bone associated with unmodified scaffolds. Moreover, Ti scaffolds with meshes of 0.8 mm showed higher osseointegration compared with 1 mm. SEM images at 6 months revealed that the bone developed not only in contact with the scaffolds, but also proliferated inside the meshes. Nano-HapSi-coated Ti implants with 0.8 mm meshes were completely covered and filled with new bone. Ti scaffolds osseointegration depended on the mesh size and the surface properties. Due to the biocompatibility and favorable osseointegration in bone defects, nano-HapSi-coated Ti scaffolds could be useful for anatomical reconstructions.

Materials Chemistry and Physics, 2016

h i g h l i g h t s Carboxyl functionalized MWCNT, HAP or HAP-Si/chitosan composites were prepare... more h i g h l i g h t s Carboxyl functionalized MWCNT, HAP or HAP-Si/chitosan composites were prepared. Composite with 10%CS had the highest homogeneity and specific surface area. Maximum albumin sorption capacity was 1.6 g/g at pH ¼ 7.5.

Studia Universitatis Babeș-Bolyai Chemia

The process parameters were studied during the fabrication of polyvinyl-alcohol (PVA) nanofibers ... more The process parameters were studied during the fabrication of polyvinyl-alcohol (PVA) nanofibers via electrospinning. The factorial experiment design model described electrospinning as an efficient, versatile approach for fabricating nanofibers. The mathematical model was developed by considering the effect of voltage, concentration, the distance between the pin and the collector, and flow rate, respectively. The influence of these parameters on the diameter and morphology of obtained PVA fibers was investigated by transmission electron microscopy (TEM). It was found that the concentration had the most significant influence on the polymer fiber diameter.

Heliyon, 2019

Magnetic field response of aqueous hydroxyapatite based magnetic suspensions.

Journal of Functional Biomaterials

Electrospun mats of PLA and PLA/Hap nanofibers produced by electrospinning were loaded with doxyc... more Electrospun mats of PLA and PLA/Hap nanofibers produced by electrospinning were loaded with doxycycline (Doxy) through physical adsorption from a solution with initial concentrations of 3 g/L, 7 g/L, and 12 g/L, respectively. The morphological characterization of the produced material was performed using scanning electron microscopy (SEM). The release profiles of Doxy were studied in situ using the differential pulse voltammetry (DPV) electrochemical method on a glassy carbon electrode (GCE) and validated through UV-VIS spectrophotometric measurements. The DPV method has been shown to be a simple, rapid, and advantageous analytical technique for real-time measurements, allowing accurate kinetics to be established. The kinetics of the release profiles were compared using model-dependent and model-independent analyses. The diffusion-controlled mechanism of Doxy release from both types of fibers was confirmed by a good fit to the Korsmeyer–Peppas model.

Materials

Zirconia-based bioceramics, one of the most important materials used for dental applications, hav... more Zirconia-based bioceramics, one of the most important materials used for dental applications, have been intensively studied in recent years due to their excellent mechanical resistance and chemical inertness in the mouth. In this work, the structural, morphological and dissolution properties of the Zr1−xMgxO2 (x = 0.05, 0.1, 0.15, 0.2, 0.25, and 0.3) system, prepared by the conventional ceramic method, were evaluated before and after immersion in saliva substitute gel (Xerostom®, Biocosmetics Laboratories, Madrid, Spain), one of the most common topical dry mouth products used in dentistry. The X-ray powder diffraction (XRPD), Fourier transform infrared spectroscopy (FTIR) and scanning electron microscopy/energy-dispersive X-ray spectroscopy (SEM/EDS) techniques were employed to investigate the phase transformations and morphology of the ceramics during the degradation process in Xerostom®. In vitro analyses showed overall good stability in the Xerostom® environment, except for the x...

Pharmaceutics

The immunomodulatory effect of a novel biomaterial obtained through electrospinning, based on pol... more The immunomodulatory effect of a novel biomaterial obtained through electrospinning, based on polylactic acid (PLA) and nano-hydroxyapatite (nano-HAP), loaded with doxycycline (doxy) was evaluated in an animal model. The treatment capabilities as a local non-surgical treatment of periodontitis was investigated on the lower incisors of Wistar rats, after the induction of localized periodontitis using the ligature technique. Following the induction of the disease, the non-surgical treatment of scaling and root planing was applied, in conjunction with the application of the new material. The results of the treatment were evaluated clinically, using the tooth mobility and gingival index scores, as well as histologically. The salivary concentrations of matrix metalloproteinase 8 (MMP-8) and plasmatic concentrations of interleukin 1 (IL-1), interleukin 6 (IL-6) and tumor necrosis factor alpha (TNF-α) were also monitored. Two weeks after the ligature application, the periodontal disease wa...

Pharmaceutics

Mucoadhesive films loaded with doxycycline hyclate (Doxy Hyc), consisting of mixtures of hydroxyp... more Mucoadhesive films loaded with doxycycline hyclate (Doxy Hyc), consisting of mixtures of hydroxypropylmethyl cellulose (HPMC) E3, K4 and polyacrylic acid (Carbopol 940), were prepared by casting method, aiming to design a formulation intended for application in the oral cavity. The obtained film formulations exhibited a Doxy Hyc content between 7.52 ± 0.42 and 7.83 ± 0.41%, which had adequate mechanical properties for application in the oral cavity and pH values in the tolerance range. The x-ray diffraction studies highlighted the amorphisation of Doxy Hyc in the preparation process and the antibiotic particles present on the surface of the films, identified in the TEM images, which ensured a burst release effect in the first 15 min of the in vitro dissolution studies, after which Doxy Hyc was released by diffusion, the data presenting a good correlation with the Peppas model, n < 0.5. The formulation F1, consisting of HPMC K4 combined with C940 in a ratio of 5:3, the most perfor...

Crystals, 2021

In the present work, ZrO2-based composites were prepared by adding different amounts of antibacte... more In the present work, ZrO2-based composites were prepared by adding different amounts of antibacterial magnesium oxide and bioactive and biocompatible hydroxyapatite (HAP) to the inert zirconia. The composites were synthesized by the conventional ceramic processing route and morpho-structurally analyzed by X-ray powder diffraction (XRPD) and scanning electron microscopy/energy dispersive X-ray spectroscopy (SEM/EDS). Two metallic dental alloys (i.e., Ni–Cr and Co–Cr) coated with a chitosan (Chit) membrane containing the prepared composites were exposed to aerated artificial saliva solutions of different pHs (i.e., 4.3, 5, 6) and the corrosion resistances were investigated by electrochemical impedance spectroscopy technique. The obtained results using the two investigated metallic dental alloys shown quasi-similar anticorrosive properties, having quasi-similar charge transfer resistance, when coated with different ZrO2-based composites. This behavior could be explained by the synerget...

Crystals, 2021

Adsorption and desorption properties of nano-hydroxyapatite (HAP) and silicon-modified hydroxyapa... more Adsorption and desorption properties of nano-hydroxyapatite (HAP) and silicon-modified hydroxyapatite (Si–HAP) were investigated with 4-aminopyridine (fampridine-4AP). The novelty of this research is the investigation of the suitability of the previously mentioned carriers for drug-delivery of 4AP. UV-VIS spectrophotometric results showed that the presence of silicon in the carrier did not significantly affect its adsorption capacity. The success of the adsorption was confirmed by thermal analysis (TG/DTA), scanning electron microscopy (SEM)/energy dispersive X-ray (EDX), Fourier transform infrared (FTIR) spectroscopy, and X-ray powder diffraction (XRPD). Drug release experiments, performed in simulated body fluid (SBF), revealed a drug release from Si–HAP that was five times slower than HAP, explained by the good chemical bonding between the silanol groups of the carrier and the 4AP functional groups. The electrochemical measurements showed a value of the polarization resistance of...

Studia Universitatis Babeș-Bolyai Chemia, 2019

The corrosion effect of the bleaching gel based on hydrogen peroxide on two types of dental metal... more The corrosion effect of the bleaching gel based on hydrogen peroxide on two types of dental metallic alloys, frequently used as restorative, prosthetic and implants materials was investigated by electrochemical impedance spectroscopy. The anti-corrosive behavior of Co-Cr and Cr-Ni alloys was found very different for the same experimental conditions. The best results were obtained with Co-Cr alloy, recommending the use of this material in dental treatments.

Materials, 2022

The present study aimed to prepare nanofibers by electrospinning in the system polylactic acid-hy... more The present study aimed to prepare nanofibers by electrospinning in the system polylactic acid-hydroxyapatite-doxycycline (PLA-HAP-Doxy) to be used as a drug delivery vehicle. Two different routes were employed for the preparation of Doxy-containing nanofibers: Immobilization on the electrospun mat’s surface and encapsulation in the fiber structure. The nanofibers obtained by Doxy encapsulation were characterized using Fourier transform infrared (FTIR) spectroscopy, thermogravimetric (TG) and differential thermal analyses (DTA) and scanning electron microscopy (SEM). The adsorption properties of pure PLA and PLA-HAP nanofibers were investigated for solutions with different Doxy concentrations (3, 7 and 12 wt%). Moreover, the desorption properties of the active substance were tested in two different fluids, simulated body fluid (SBF) and phosphate buffer solution (PBS), to evidence the drug release properties. In vitro drug release studies were performed and different drug release ki...

Nemzetközi Vegyészkonferencia, Oct 16, 2020

In addition to biocompatibility and stability, the way in which the drug is released is also a de... more In addition to biocompatibility and stability, the way in which the drug is released is also a determining parameter when designing drug carriers. The main expectation from such systems is regulated, predictive behavior. According to the suitable release kinetics, an effective drug concentration is initially released from the carriers and then this level is stabilized in the organism for as long as possible [1,2]. The aim of our study is to prepare various nano-hydroxyapatite (Hap) based carriers, to evaluation their adsorption and desorption properties with ibuprofen (synthetic anti-inflammatory) and anthocyanin (natural anti-inflammatory, antioxidant). The properties of Hap, which is also used as a local drug carrier, were improved with different nano-carbon additives (fullerene, graphene-oxide, multiwall functionalized carbon nanotube) and gelatin. The adsorption of both drugs has been shown to be successful, but the in vitro release mechanism showed different behavior not only for each carrier but also for each drug. Although gelatin has a controlled effect on dissolution processes, the release of anthocyanin in simulated body fluid was irregular. Ibuprofen shows regular dissolution in all cases, the desorption process corresponded to first-order kinetics, Korsmeyer-Peppas model and Higuchi model.

Applied Sciences, 2021

This study aims to investigate the quality and vulnerability of surface water (Aries River catchm... more This study aims to investigate the quality and vulnerability of surface water (Aries River catchment) in order to identify the impact of past mining activities. For this purpose, the pollution and water quality indices, Piper and Durov plots, as well vulnerability modeling maps were used. The obtained results indicate that the water samples were contaminated with As, Fe, Mn, Pb and have relatively high concentrations of SO42−, HCO3−, TDS, Ca, K, Mg and high values for the electrical conductivity. Possible sources of the high content of chemicals could be the natural processes or the inputs of the mine drainage. Generally, according to the pollution indices, which were correlated to high concentrations of heavy metals, especially with Pb, Fe and Mn, the water samples were characterized by heavy metals pollution. The water quality index classified the studied water samples into five different classes of quality, namely: unsuitable for drinking, poor, medium, good and excellent quality...

Metals, 2020

Background: SLM (Selective Laser Melting)–manufactured Titanium (Ti) scaffolds have a significant... more Background: SLM (Selective Laser Melting)–manufactured Titanium (Ti) scaffolds have a significant value for bone reconstructions in the oral and maxillofacial surgery field. While their mechanical properties and biocompatibility have been analysed, there is still no adequate information regarding tissue integration. Therefore, the aim of this study is a comprehensive systematic assessment of the essential parameters (porosity, pore dimension, surface treatment, shape) required to provide the long-term performance of Ti SLM medical implants. Materials and methods: A systematic literature search was conducted via electronic databases PubMed, Medline and Cochrane, using a selection of relevant search MeSH terms. The literature review was conducted using the preferred reporting items for systematic reviews and meta-analysis (PRISMA). Results: Within the total of 11 in vitro design studies, 9 in vivo studies, and 4 that had both in vitro and in vivo designs, the results indicated that SL...

Studia Universitatis Babeș-Bolyai. Chemia

In the current study a model based stability analysis of a continuous mixed suspension mixed prod... more In the current study a model based stability analysis of a continuous mixed suspension mixed product removal crystallizer, widely used in pilot and industrial scale, is investigated. The population balance approach is used to model the size distribution of solid particulate phase, taking into consideration the nucleation and size independent growth of particles. The model was solved with the standard method of moments, computing the leading moments of particle size distribution. The Lyapunov's stability theory is used for mapping the unstable operation regions of the crystallizer, by computing the eigenvalues of Jacobian matrix of the governing equation system. In unstable region numerical simulations are performed to visualize the effects of the generated temporal oscillations into particulate properties. Based on the simulations, useful conclusions can be made from the point of view of operating, optimizing and control of the continuous crystallizer.

Biotechnology and Bioprocess Engineering, Sep 1, 2019

Customized medical implants obtained by selective laser melting have an important applicability d... more Customized medical implants obtained by selective laser melting have an important applicability due the accurate architecture which promotes the osteointegration, osteoconduction, and osteoinduction. This study assessed the in vitro effect of titanium scaffolds, both pure and covered with a layer of hydroxyapatite, on mesenchymal stem cells harvested from various oral tissues. Eight titanium implants were manufactured by selective laser melting, obtaining a porosity of 63.4% and a pore size of 600 µm. Four matrices were covered with nano-hydroxyapatite. Four lines of mesenchymal stem cells isolated from the apical papilla, the dental pulp, the inter-radicular bone, and the tuberosity bone were seeded on the implants. The cells' proliferation, viability, and differentiation into the osteoblastic lineage were assessed after 18 days, using light microscopy and fluorescence. Our results indicated that the titanium matrices did not exert cytotoxic effect. The cells seeded on titanium matrices conditioned with nanohydroxyapatite had a slightly higher proliferation rate. The stem cells isolated from the inter-radicular bone had the most intense proliferation and differentiation towards the osteoblastic lineage showing a nodular architecture. In conclusion, the oral mesenchymal stem cells have the potential to promote and improve bone regeneration when associated with the titanium scaffolds manufactured by selective laser melting, either non-coated or coated with hydroxyapatite. These findings open new perspectives for the bone reconstruction in the oral and maxillofacial surgery field.

Studia Universitatis Babes-bolyai Chemia, Mar 31, 2021

JUDITH-HAJNAL BARTHA-VARI a , RENÁTA ELEKES-DARABONT a , LAURA-EDIT BARABÁS a , RÉKA BARABÁS a, *... more JUDITH-HAJNAL BARTHA-VARI a , RENÁTA ELEKES-DARABONT a , LAURA-EDIT BARABÁS a , RÉKA BARABÁS a, * ABSTRACT. A new and efficient immobilization method of phenylalanine ammonia-lyase was obtained using hydroxyapatite (HAP) and hydroxyapatitecarbon nanotube, gelatin and chitosan-composites (HAP-CNT, HAP-GEL and HAP-CS) as support material. HAP and HAP composites were characterized by transmission electron microscopy (TEM), laser diffraction particle size analyzer and XRD measurements. The obtained nanobioconjugates were tested in the ammonia elimination reactions from L-phenylalanine (L-1). The reusability and the time-course profile of the immobilized enzyme preparation was also tested. While the biocatalyst obtained by using HAP-CS-15 as support material provided the highest conversion rate in the ammonia elimination reaction from L-1 (98,1% compared to 98,5% obtained using the non-immobilized enzyme), the most stable biocatalyst proved to be HAP-PAL, which maintained more than 80% of its initial activity even after 5 cycles of reuse.

Materials Chemistry and Physics, Aug 1, 2023

Arabian Journal for Science and Engineering, 2019

Hydroxyapatite (HAP), the main mineral component of bone and tooth enamel, has become an importan... more Hydroxyapatite (HAP), the main mineral component of bone and tooth enamel, has become an important biomaterial in orthopedic and dental applications. However, its low fracture toughness, poor tensile strength and wear resistance make it not suitable to be used in bone tissue engineering applications, the improvement of mechanical properties of HAP using different additives being still a great challenge. Nowadays, the most used additives for reinforcement are graphene oxide (GO) and single-or multi-walled carbon nanotubes (MWCNTs). The present study reports their successful incorporation of MWCNTs and GO (0.5, 1.0 and 2.0 wt%) into the HAP matrix. The prepared HAP-based nanocomposites (NCs) were characterized by X-ray diffraction, laser diffraction, scanning and transmission electron microscopy, thermal analysis and Raman spectroscopy. Moreover, the UV-Vis spectroscopy was used to investigate the desorption properties of obtained NCs by using ibuprofen, one of the most common prescribed analgesic nonsteroidal anti-inflammatory drugs. It was found that CNTs addition does not have a major influence on desorption efficiency, while the addition of GO evidenced an increase in desorption efficiency over time for all the studied NCs.

Journal of Materials Science: Materials in Medicine, 2019

The aim of this study was to assess the osseointegration of two series of titanium (Ti) scaffolds... more The aim of this study was to assess the osseointegration of two series of titanium (Ti) scaffolds with 0.8 and 1 mm cell size obtained by Selective Laser Melting (SLM) technique. One of the series had the Ti surface unmodified, while the other had the Ti surface coated with silicon-substituted nano-hydroxyapatite (nano-HapSi). The scaffolds were implanted in the femur bone defects of 6 White Californian male rabbits: three animals were implanted with 0.8 mm cell size scaffolds and three animals with 1 mm cell size scaffolds, respectively. The bone fragments and scaffolds harvested at 2, 4 and 6 months were histologically analyzed using conventional light microscopy (LM) and scanning electron microscopy (SEM) for the qualitative evaluation of the bone tissue formed in contact with the scaffold. Both LM and SEM images indicated a better osseointegration for nano-HapSi coated Ti scaffolds. LM revealed that the compact bone formed in the proximity of nano-HapSi-coated scaffolds was better organized than spongy bone associated with unmodified scaffolds. Moreover, Ti scaffolds with meshes of 0.8 mm showed higher osseointegration compared with 1 mm. SEM images at 6 months revealed that the bone developed not only in contact with the scaffolds, but also proliferated inside the meshes. Nano-HapSi-coated Ti implants with 0.8 mm meshes were completely covered and filled with new bone. Ti scaffolds osseointegration depended on the mesh size and the surface properties. Due to the biocompatibility and favorable osseointegration in bone defects, nano-HapSi-coated Ti scaffolds could be useful for anatomical reconstructions.

Materials Chemistry and Physics, 2016

h i g h l i g h t s Carboxyl functionalized MWCNT, HAP or HAP-Si/chitosan composites were prepare... more h i g h l i g h t s Carboxyl functionalized MWCNT, HAP or HAP-Si/chitosan composites were prepared. Composite with 10%CS had the highest homogeneity and specific surface area. Maximum albumin sorption capacity was 1.6 g/g at pH ¼ 7.5.

Studia Universitatis Babeș-Bolyai Chemia

The process parameters were studied during the fabrication of polyvinyl-alcohol (PVA) nanofibers ... more The process parameters were studied during the fabrication of polyvinyl-alcohol (PVA) nanofibers via electrospinning. The factorial experiment design model described electrospinning as an efficient, versatile approach for fabricating nanofibers. The mathematical model was developed by considering the effect of voltage, concentration, the distance between the pin and the collector, and flow rate, respectively. The influence of these parameters on the diameter and morphology of obtained PVA fibers was investigated by transmission electron microscopy (TEM). It was found that the concentration had the most significant influence on the polymer fiber diameter.

Heliyon, 2019

Magnetic field response of aqueous hydroxyapatite based magnetic suspensions.

Journal of Functional Biomaterials

Electrospun mats of PLA and PLA/Hap nanofibers produced by electrospinning were loaded with doxyc... more Electrospun mats of PLA and PLA/Hap nanofibers produced by electrospinning were loaded with doxycycline (Doxy) through physical adsorption from a solution with initial concentrations of 3 g/L, 7 g/L, and 12 g/L, respectively. The morphological characterization of the produced material was performed using scanning electron microscopy (SEM). The release profiles of Doxy were studied in situ using the differential pulse voltammetry (DPV) electrochemical method on a glassy carbon electrode (GCE) and validated through UV-VIS spectrophotometric measurements. The DPV method has been shown to be a simple, rapid, and advantageous analytical technique for real-time measurements, allowing accurate kinetics to be established. The kinetics of the release profiles were compared using model-dependent and model-independent analyses. The diffusion-controlled mechanism of Doxy release from both types of fibers was confirmed by a good fit to the Korsmeyer–Peppas model.

Materials

Zirconia-based bioceramics, one of the most important materials used for dental applications, hav... more Zirconia-based bioceramics, one of the most important materials used for dental applications, have been intensively studied in recent years due to their excellent mechanical resistance and chemical inertness in the mouth. In this work, the structural, morphological and dissolution properties of the Zr1−xMgxO2 (x = 0.05, 0.1, 0.15, 0.2, 0.25, and 0.3) system, prepared by the conventional ceramic method, were evaluated before and after immersion in saliva substitute gel (Xerostom®, Biocosmetics Laboratories, Madrid, Spain), one of the most common topical dry mouth products used in dentistry. The X-ray powder diffraction (XRPD), Fourier transform infrared spectroscopy (FTIR) and scanning electron microscopy/energy-dispersive X-ray spectroscopy (SEM/EDS) techniques were employed to investigate the phase transformations and morphology of the ceramics during the degradation process in Xerostom®. In vitro analyses showed overall good stability in the Xerostom® environment, except for the x...

Pharmaceutics

The immunomodulatory effect of a novel biomaterial obtained through electrospinning, based on pol... more The immunomodulatory effect of a novel biomaterial obtained through electrospinning, based on polylactic acid (PLA) and nano-hydroxyapatite (nano-HAP), loaded with doxycycline (doxy) was evaluated in an animal model. The treatment capabilities as a local non-surgical treatment of periodontitis was investigated on the lower incisors of Wistar rats, after the induction of localized periodontitis using the ligature technique. Following the induction of the disease, the non-surgical treatment of scaling and root planing was applied, in conjunction with the application of the new material. The results of the treatment were evaluated clinically, using the tooth mobility and gingival index scores, as well as histologically. The salivary concentrations of matrix metalloproteinase 8 (MMP-8) and plasmatic concentrations of interleukin 1 (IL-1), interleukin 6 (IL-6) and tumor necrosis factor alpha (TNF-α) were also monitored. Two weeks after the ligature application, the periodontal disease wa...

Pharmaceutics

Mucoadhesive films loaded with doxycycline hyclate (Doxy Hyc), consisting of mixtures of hydroxyp... more Mucoadhesive films loaded with doxycycline hyclate (Doxy Hyc), consisting of mixtures of hydroxypropylmethyl cellulose (HPMC) E3, K4 and polyacrylic acid (Carbopol 940), were prepared by casting method, aiming to design a formulation intended for application in the oral cavity. The obtained film formulations exhibited a Doxy Hyc content between 7.52 ± 0.42 and 7.83 ± 0.41%, which had adequate mechanical properties for application in the oral cavity and pH values in the tolerance range. The x-ray diffraction studies highlighted the amorphisation of Doxy Hyc in the preparation process and the antibiotic particles present on the surface of the films, identified in the TEM images, which ensured a burst release effect in the first 15 min of the in vitro dissolution studies, after which Doxy Hyc was released by diffusion, the data presenting a good correlation with the Peppas model, n < 0.5. The formulation F1, consisting of HPMC K4 combined with C940 in a ratio of 5:3, the most perfor...

Crystals, 2021

In the present work, ZrO2-based composites were prepared by adding different amounts of antibacte... more In the present work, ZrO2-based composites were prepared by adding different amounts of antibacterial magnesium oxide and bioactive and biocompatible hydroxyapatite (HAP) to the inert zirconia. The composites were synthesized by the conventional ceramic processing route and morpho-structurally analyzed by X-ray powder diffraction (XRPD) and scanning electron microscopy/energy dispersive X-ray spectroscopy (SEM/EDS). Two metallic dental alloys (i.e., Ni–Cr and Co–Cr) coated with a chitosan (Chit) membrane containing the prepared composites were exposed to aerated artificial saliva solutions of different pHs (i.e., 4.3, 5, 6) and the corrosion resistances were investigated by electrochemical impedance spectroscopy technique. The obtained results using the two investigated metallic dental alloys shown quasi-similar anticorrosive properties, having quasi-similar charge transfer resistance, when coated with different ZrO2-based composites. This behavior could be explained by the synerget...

Crystals, 2021

Adsorption and desorption properties of nano-hydroxyapatite (HAP) and silicon-modified hydroxyapa... more Adsorption and desorption properties of nano-hydroxyapatite (HAP) and silicon-modified hydroxyapatite (Si–HAP) were investigated with 4-aminopyridine (fampridine-4AP). The novelty of this research is the investigation of the suitability of the previously mentioned carriers for drug-delivery of 4AP. UV-VIS spectrophotometric results showed that the presence of silicon in the carrier did not significantly affect its adsorption capacity. The success of the adsorption was confirmed by thermal analysis (TG/DTA), scanning electron microscopy (SEM)/energy dispersive X-ray (EDX), Fourier transform infrared (FTIR) spectroscopy, and X-ray powder diffraction (XRPD). Drug release experiments, performed in simulated body fluid (SBF), revealed a drug release from Si–HAP that was five times slower than HAP, explained by the good chemical bonding between the silanol groups of the carrier and the 4AP functional groups. The electrochemical measurements showed a value of the polarization resistance of...

Studia Universitatis Babeș-Bolyai Chemia, 2019

The corrosion effect of the bleaching gel based on hydrogen peroxide on two types of dental metal... more The corrosion effect of the bleaching gel based on hydrogen peroxide on two types of dental metallic alloys, frequently used as restorative, prosthetic and implants materials was investigated by electrochemical impedance spectroscopy. The anti-corrosive behavior of Co-Cr and Cr-Ni alloys was found very different for the same experimental conditions. The best results were obtained with Co-Cr alloy, recommending the use of this material in dental treatments.

Materials, 2022

The present study aimed to prepare nanofibers by electrospinning in the system polylactic acid-hy... more The present study aimed to prepare nanofibers by electrospinning in the system polylactic acid-hydroxyapatite-doxycycline (PLA-HAP-Doxy) to be used as a drug delivery vehicle. Two different routes were employed for the preparation of Doxy-containing nanofibers: Immobilization on the electrospun mat’s surface and encapsulation in the fiber structure. The nanofibers obtained by Doxy encapsulation were characterized using Fourier transform infrared (FTIR) spectroscopy, thermogravimetric (TG) and differential thermal analyses (DTA) and scanning electron microscopy (SEM). The adsorption properties of pure PLA and PLA-HAP nanofibers were investigated for solutions with different Doxy concentrations (3, 7 and 12 wt%). Moreover, the desorption properties of the active substance were tested in two different fluids, simulated body fluid (SBF) and phosphate buffer solution (PBS), to evidence the drug release properties. In vitro drug release studies were performed and different drug release ki...

Nemzetközi Vegyészkonferencia, Oct 16, 2020

In addition to biocompatibility and stability, the way in which the drug is released is also a de... more In addition to biocompatibility and stability, the way in which the drug is released is also a determining parameter when designing drug carriers. The main expectation from such systems is regulated, predictive behavior. According to the suitable release kinetics, an effective drug concentration is initially released from the carriers and then this level is stabilized in the organism for as long as possible [1,2]. The aim of our study is to prepare various nano-hydroxyapatite (Hap) based carriers, to evaluation their adsorption and desorption properties with ibuprofen (synthetic anti-inflammatory) and anthocyanin (natural anti-inflammatory, antioxidant). The properties of Hap, which is also used as a local drug carrier, were improved with different nano-carbon additives (fullerene, graphene-oxide, multiwall functionalized carbon nanotube) and gelatin. The adsorption of both drugs has been shown to be successful, but the in vitro release mechanism showed different behavior not only for each carrier but also for each drug. Although gelatin has a controlled effect on dissolution processes, the release of anthocyanin in simulated body fluid was irregular. Ibuprofen shows regular dissolution in all cases, the desorption process corresponded to first-order kinetics, Korsmeyer-Peppas model and Higuchi model.

Applied Sciences, 2021

This study aims to investigate the quality and vulnerability of surface water (Aries River catchm... more This study aims to investigate the quality and vulnerability of surface water (Aries River catchment) in order to identify the impact of past mining activities. For this purpose, the pollution and water quality indices, Piper and Durov plots, as well vulnerability modeling maps were used. The obtained results indicate that the water samples were contaminated with As, Fe, Mn, Pb and have relatively high concentrations of SO42−, HCO3−, TDS, Ca, K, Mg and high values for the electrical conductivity. Possible sources of the high content of chemicals could be the natural processes or the inputs of the mine drainage. Generally, according to the pollution indices, which were correlated to high concentrations of heavy metals, especially with Pb, Fe and Mn, the water samples were characterized by heavy metals pollution. The water quality index classified the studied water samples into five different classes of quality, namely: unsuitable for drinking, poor, medium, good and excellent quality...

Metals, 2020

Background: SLM (Selective Laser Melting)–manufactured Titanium (Ti) scaffolds have a significant... more Background: SLM (Selective Laser Melting)–manufactured Titanium (Ti) scaffolds have a significant value for bone reconstructions in the oral and maxillofacial surgery field. While their mechanical properties and biocompatibility have been analysed, there is still no adequate information regarding tissue integration. Therefore, the aim of this study is a comprehensive systematic assessment of the essential parameters (porosity, pore dimension, surface treatment, shape) required to provide the long-term performance of Ti SLM medical implants. Materials and methods: A systematic literature search was conducted via electronic databases PubMed, Medline and Cochrane, using a selection of relevant search MeSH terms. The literature review was conducted using the preferred reporting items for systematic reviews and meta-analysis (PRISMA). Results: Within the total of 11 in vitro design studies, 9 in vivo studies, and 4 that had both in vitro and in vivo designs, the results indicated that SL...

Studia Universitatis Babeș-Bolyai. Chemia

In the current study a model based stability analysis of a continuous mixed suspension mixed prod... more In the current study a model based stability analysis of a continuous mixed suspension mixed product removal crystallizer, widely used in pilot and industrial scale, is investigated. The population balance approach is used to model the size distribution of solid particulate phase, taking into consideration the nucleation and size independent growth of particles. The model was solved with the standard method of moments, computing the leading moments of particle size distribution. The Lyapunov's stability theory is used for mapping the unstable operation regions of the crystallizer, by computing the eigenvalues of Jacobian matrix of the governing equation system. In unstable region numerical simulations are performed to visualize the effects of the generated temporal oscillations into particulate properties. Based on the simulations, useful conclusions can be made from the point of view of operating, optimizing and control of the continuous crystallizer.