Your browser doesn't support javascript.
loading
Mostrar: 20 | 50 | 100
Resultados 1 - 20 de 49
Filtrar
Mais filtros

Base de dados
Tipo de documento
Intervalo de ano de publicação
1.
Int J Pharm ; 661: 124420, 2024 Aug 15.
Artigo em Inglês | MEDLINE | ID: mdl-38971512

RESUMO

Colorectal cancer represents a worldwide spread type of cancer and it is regarded as one of the leading death causes, along with lung, breast, and prostate cancers. Since conventional surgical resection and chemotherapy proved limited efficiency, the use of alternative drug delivery systems that ensure the controlled release of cytostatic agents possess immense potential for treatment. In this regard, the present study aimed to develop and evaluate the efficiency of a series of irinotecan-loaded magnetite-silica core-shell systems. The magnetite particles were obtained through a solvothermal treatment, while the silica shell was obtained through the Stöber method directly onto the surface of magnetite particles. Subsequently, the core-shell systems were physico-chemically and morpho-structurally evaluated trough X-ray diffraction (XRD) and (high-resolution) transmission electron microscopy ((HR-)TEM) equipped with a High Annular Angular Dark Field Detector (HAADF) for elemental mapping. After the irinotecan loading, the drug delivery systems were evaluated through Fourier-transform infrared spectroscopy (FT-IR), thermogravimetry and differential scanning calorimetry (TG-DSC), and UV-Vis spectrophotometry. Additionally, the Brunauer-Emmett-Teller (BET) method was employed for determining the surface area and pore volume of the systems. The biological functionality of the core-shells was investigated through the MTT assay performed on both normal and cancer cells. The results of the study confirmed the formation of highly crystalline magnetite particles comprising the core and mesoporous silica layers of sizes varying between 2 and 7 nm as the shell. Additionally, the drug loading and release was dependent on the type of the silica synthesis procedure, since the lack of hexadecyltrimethylammonium bromide (CTAB) resulted in higher drug loading but lower cumulative release. Moreover, the nanostructured systems demonstrated a targeted efficiency towards HT-29 colorectal adenocarcinoma cells, as in the case of normal L929 fibroblast cells, the cell viability was higher than for the pristine drug. In this manner, this study provides the means and procedures for developing drug delivery systems with applicability in the treatment of cancer.


Assuntos
Sobrevivência Celular , Neoplasias Colorretais , Liberação Controlada de Fármacos , Irinotecano , Dióxido de Silício , Irinotecano/administração & dosagem , Irinotecano/química , Dióxido de Silício/química , Humanos , Neoplasias Colorretais/tratamento farmacológico , Neoplasias Colorretais/patologia , Sobrevivência Celular/efeitos dos fármacos , Portadores de Fármacos/química , Sistemas de Liberação de Medicamentos , Antineoplásicos Fitogênicos/administração & dosagem , Antineoplásicos Fitogênicos/química , Antineoplásicos Fitogênicos/farmacologia , Nanopartículas de Magnetita/química , Linhagem Celular Tumoral , Óxido Ferroso-Férrico/química , Óxido Ferroso-Férrico/administração & dosagem
2.
Polymers (Basel) ; 16(11)2024 May 27.
Artigo em Inglês | MEDLINE | ID: mdl-38891458

RESUMO

A challenge in tissue engineering and the pharmaceutical sector is the development of controlled local release of drugs that raise issues when systemic administration is applied. Strontium is an example of an effective anti-osteoporotic agent, used in treating osteoporosis due to both anti-resorptive and anabolic mechanisms of action. Designing bone scaffolds with a higher capability of promoting bone regeneration is a topical research subject. In this study, we developed composite multi-layer three-dimensional (3D) scaffolds for bone tissue engineering based on nano-hydroxyapatite (HA), Sr-containing nano-hydroxyapatite (SrHA), and poly-ε-caprolactone (PCL) through the material extrusion fabrication technique. Previously obtained HA and SrHA with various Sr content were used for the composite material. The chemical, morphological, and biocompatibility properties of the 3D-printed scaffolds obtained using HA/SrHA and PCL were investigated. The 3D composite scaffolds showed good cytocompatibility and osteogenic potential, which is specifically recommended in applications when faster mineralization is needed, such as osteoporosis treatment.

3.
Diagnostics (Basel) ; 14(7)2024 Mar 29.
Artigo em Inglês | MEDLINE | ID: mdl-38611634

RESUMO

Nasopharyngeal carcinoma is one of the most common malignant tumors in the head and neck region. The carcinogenesis is a complex process stimulated by many factors. Although the etiological factors and pathogenic mechanisms are not elucidated, the genetic susceptibility, environmental factors, and association with latent infection with Epstein-Barr Virus play an important role. The aim of this study was to present the main clinical and epidemiological data, as well as the morphological aspects and the immunohistochemical profile, of patients with nasopharyngeal carcinoma diagnosed in western Romania. The study was retrospective and included 36 nasopharyngeal carcinomas. The histopathological diagnosis was completed using immunohistochemical reactions for the following antibodies: p63, p53 and p16 protein, cytokeratins (CK) AE1/AE3, CK5, CK7, CK20 and 34ßE12, epithelial membrane antigen (EMA), Epstein-Barr virus (EBV), leukocyte common antigen (LCA), CD20, CD4, CD8, CD68, CD117, and CD1a. The squamous malignant component of nasopharyngeal carcinoma presented with positivity for cytokeratins AE1/AE3, CK5, 34ßE12, and p63. Undifferentiated nasopharyngeal carcinoma was positive for EMA in 67% of cases, and 28% of cases showed an immunoreaction for CD117 in the malignant epithelial component. Also, the p53 protein was positive in all the cases. One case of undifferentiated nasopharyngeal carcinoma was p16-positive, and two cases were positive for EBV. A peri- and intratumor cellular infiltrate rich in lymphocytes, with a predominance of CD20-positive B lymphocytes, interspersed with T lymphocytes, was observed. The T cells were CD4- and CD8-positive, predominantly intratumoral, and the CD4:CD8 ratio was 1:1 for 75% of the undifferentiated subtype and 89% for differentiated non-keratinized squamous cell carcinoma. All subtypes of nasopharyngeal carcinoma presented with an inflammatory infiltrate with numerous plasma cells, eosinophils, and dendritic cells, presenting as antigen CD1a- and CD68-positive, as well as in CD117-positive mast cells.

4.
Diagnostics (Basel) ; 13(23)2023 Nov 23.
Artigo em Inglês | MEDLINE | ID: mdl-38066754

RESUMO

Metastatic disease is a complex and sequential process that involves the migration of tumor cells from the primary site to distant areas. This metastatic pathway is not always predictable. Therefore, this paper presents three rare cases of unusual metastases, due to their primary site: two metastases of a clear cell renal cell carcinoma, one gingival, and one nasal, as well as a mandibular metastasis of a hepatocellular carcinoma. In all cases, an incisional biopsy was performed in order to find out the diagnosis. After microscopical examination of morphological Hematoxylin and Eosin-stained slides, for all cases, immunohistochemical reactions were performed to support the primary tumor site. Two cases had a previous histopathological diagnosis of a primary tumor, while for the third case, the metastatic lesion represented the first manifestation of the neoplastic disease, with an unfavorable prognosis.

5.
J Funct Biomater ; 14(12)2023 Nov 28.
Artigo em Inglês | MEDLINE | ID: mdl-38132814

RESUMO

The current study reports the use of silver (Ag) and samarium (Sm) as dopants to improve the properties of standard bioglass in terms of biological performance. This experiment considers thin films of doped bioglass obtained by pulsed laser deposition (PLD) and spin coating (SC). For both methods, some parameters were gradually varied, as the main objective was to produce a bioglass that could be used in biomedical fields. In order to study the morphology, the phase composition and other properties, the samples obtained were subjected to multiple analyses, such as thermal analysis, scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDX), Fourier-transform infrared (FT-IR), Raman spectroscopy, and x-ray diffraction (XRD). Furthermore, the in vitro bioactivity of the samples, as assessed through simulated body fluid (SBF) immersion, as well as immunocytochemistry and evaluation of actin filaments, assessed through fluorescence microscopy, are reported. The results confirmed the formation of the designed vitreous target employed as the source of material in the PLD experiments only at sintering temperatures below 800 °C; this vitreous nature was preserved in the grown film as well. The presence of Ag and Ce dopants in the parent glassy matrix was validated for all stages, from powder, to target, to PLD/SC-derived coatings. Additionally, it was demonstrated that the surface topography of the layers can be adjusted by using substrates with different roughness or by modulating the processing parameters, such as substrate temperature and working pressure in PLD, rotation speed, and number of layers in SC. The developed material was found to be highly bioactive after 28 days of immersion in SBF, but it was also found to be a potential candidate for inhibiting the growth of Gram-negative bacteria and a suitable support for cell growth and proliferation.

6.
Materials (Basel) ; 16(22)2023 Nov 09.
Artigo em Inglês | MEDLINE | ID: mdl-38005035

RESUMO

In this study, a sol-gel film based on lead sulfide (PbS) quantum dots incorporated into a host network was synthesized as a special nanostructured composite material with potential applications in temperature sensor systems. This work dealt with the optical, structural, and morphological properties of a representative PbS quantum dot (QD)-containing thin film belonging to the Al2O3-SiO2-P2O5 system. The film was prepared using the sol-gel method combined with the spin coating technique, starting from a precursor solution containing a suspension of PbS QDs in toluene with a narrow size distribution and coated on a glass substrate in a multilayer process, followed by annealing of each deposited layer. The size (approximately 10 nm) of the lead sulfide nanocrystallites was validated by XRD and by the quantum confinement effect based on the band gap value and by TEM results. The photoluminescence peak of 1505 nm was very close to that of the precursor PbS QD solution, which demonstrated that the synthesis route of the film preserved the optical emission characteristic of the PbS QDs. The photoluminescence of the lead sulfide QD-containing film in the near infrared domain demonstrates that this material is a promising candidate for future sensing applications in temperature monitoring.

7.
Nanomaterials (Basel) ; 13(22)2023 Nov 12.
Artigo em Inglês | MEDLINE | ID: mdl-37999288

RESUMO

Fine-tuning of grain sizes can significantly influence the interaction between different dielectric phenomena, allowing the development of materials with tailored dielectric resistivity. By virtue of various synthesis mechanisms, a pathway to manipulate grain sizes and, consequently, tune the material's dielectric response is revealed. Understanding these intricate relationships between granulation and dielectric properties can pave the way for designing and optimizing materials for specific applications where tailored dielectric responses are sought. The experimental part involved the fabrication of dense BCT-BZT ceramics with different grain sizes by varying the synthesis (conventional solid-state reaction route and sol-gel) and consolidation methods. Both consolidation methods produced well-crystallized specimens, with Ba0.85Ca0.15O3Ti0.9Zr0.1 (BCTZ) perovskite as the major phase. Conventional sintering resulted in microstructured and submicron-structured BCT-BZT ceramics, with average grain sizes of 2.35 µm for the solid-state sample and 0.91 µm for the sol-gel synthesized ceramic. However, spark plasma sintering produced a nanocrystalline specimen with an average grain size of 67.5 nm. As the grain size decreases, there is a noticeable decrease in the maximum permittivity, a significant reduction in dielectric losses, and a shifting of the Curie temperature towards lower values.

8.
Nanomaterials (Basel) ; 13(22)2023 Nov 19.
Artigo em Inglês | MEDLINE | ID: mdl-37999328

RESUMO

A novel high-entropy perovskite powder with the composition Bi0.2K0.2Ba0.2Sr0.2Ca0.2TiO3 was successfully synthesized using a modified Pechini method. The precursor powder underwent characterization through Fourier Transform Infrared Spectroscopy and thermal analysis. The resultant Bi0.2K0.2Ba0.2Sr0.2Ca0.2TiO3 powder, obtained post-calcination at 900 °C, was further examined using a variety of techniques including X-ray diffraction, Raman spectroscopy, X-ray fluorescence, scanning electron microscopy, and transmission electron microscopy. Ceramic samples were fabricated by conventional sintering at various temperatures (900, 950, and 1000 °C). The structure, microstructure, and dielectric properties of these ceramics were subsequently analyzed and discussed. The ceramics exhibited a two-phase composition comprising cubic and tetragonal perovskites. The grain size was observed to increase from 35 to 50 nm, contingent on the sintering temperature. All ceramic samples demonstrated relaxor behavior with a dielectric maximum that became more flattened and shifted towards lower temperatures as the grain size decreased.

9.
J Clin Med ; 12(18)2023 Sep 07.
Artigo em Inglês | MEDLINE | ID: mdl-37762770

RESUMO

Anesthetic techniques play an important role in the outcome of the therapeutic procedures in dentistry. Although inferior alveolar nerve block (IANB) anesthesia is currently the most often used, there are situations that imply the need of an alternative anesthesia technique to overcome the potential risks and complications. The aim of the study was to evaluate the efficacy of the retromolar triangle anesthesia technique in achieving the desired nerve block, while evaluating the duration of the anesthesia for the included cases. METHODS: The present prospective study included 50 subjects that had indication of inferior molar extraction. The performed anesthesia technique for these cases was the retromolar triangle approach, and the analyzed parameters for evaluating the efficacy of this anesthesia technique were the positive nerve block of the branches involved in the area (inferior alveolar, buccal, and lingual nerves) and the duration of the anesthesia. RESULTS: The efficiency of the retromolar triangle anesthesia technique was positive in 64% of the cases for the inferior alveolar nerve, 46% of the cases for the lingual nerve, and 22% of the cases for the buccal nerve. The duration of the anesthesia revealed a mean value of 72.4 min, suggesting that the duration is an essential factor in its effectiveness. CONCLUSIONS: Retromolar triangle anesthesia can be a viable option for clinicians, offering a simple and easy approach for the management of clinical cases.

10.
Materials (Basel) ; 16(18)2023 Sep 11.
Artigo em Inglês | MEDLINE | ID: mdl-37763434

RESUMO

A convenient and low-cost sol-gel approach for the one-step synthesis of ZnO-P2O5-rGO nanostructures with tuned bandgap and fluorescence was investigated. The obtained hybrid nanostructures exploit the properties of zinc oxide, graphene oxide and phosphorous oxide as promising candidates for a wide range of optoelectronic applications. A predominant amorphous structure, ZnO-P2O5-rGO, containing ZnO nanorods was evidenced by X-ray diffraction analysis (XRD) and scanning electron microscopy (SEM). The estimated size of the ZnO nanorods in nanostructures with P2O5 was noticed to decrease when the P2O5/ZnO ratio was increased. The presence of ZnO, P2O5 and rGO was confirmed by Fourier-transform infrared spectroscopy (FTIR) and Raman investigation. P2O5 was noticed to tune the bandgap and the fluorescence emissions of the nanostructured films, as estimated by UV-Vis-NIR and fluorescence spectroscopy, respectively. The electrical measurements performed at room temperature showed that the main influence on the film's resistivity does not come from the 1% rGO doping but from the P2O5/ZnO ratio. It was found that a 10/90 molar ratio of P2O5/ZnO decreases the resistivity almost seven-fold compared with rGO-doped ZnO films.

11.
Materials (Basel) ; 16(16)2023 Aug 09.
Artigo em Inglês | MEDLINE | ID: mdl-37629839

RESUMO

Tissue engineering requires new materials that can be used to replace damaged bone parts. Since hydroxyapatite, currently widely used, has low mechanical resistance, silicate ceramics can represent an alternative. The aim of this study was to obtain porous ceramics based on diopside (CaMgSi2O6) and akermanite (Ca2MgSi2O7) obtained at low sintering temperatures. The powder synthesized by the sol-gel method was pressed in the presence of a porogenic agent represented by commercial sucrose in order to create the desired porosity. The ceramic bodies obtained after sintering thermal treatment at 1050 °C and 1250 °C, respectively, were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), and Fourier transform infrared spectroscopy (FTIR) to determine the chemical composition. The open porosity was situated between 32.5 and 34.6%, and the compressive strength had a maximum value of 11.4 MPa for the samples sintered at 1250 °C in the presence of a 20% wt porogenic agent. A cell viability above 70% and the rapid development of an apatitic phase layer make these materials good candidates for use in hard tissue engineering.

12.
Nanomaterials (Basel) ; 13(15)2023 Jul 31.
Artigo em Inglês | MEDLINE | ID: mdl-37570539

RESUMO

A composite based on calcium sulphate hemihydrate enhanced with Zn- or B-doped hydroxyapatite nanoparticles was fabricated and evaluated for bone graft applications. The investigations of their structural and morphological properties were performed by X-ray diffraction (XRD), Fourier transform infrared (FTIR) spectroscopy, scanning electron microscopy (SEM), and energy dispersive X-ray (EDX) spectroscopy techniques. To study the bioactive properties of the obtained composites, soaking tests in simulated body fluid (SBF) were performed. The results showed that the addition of 2% Zn results in an increase of 2.27% in crystallinity, while the addition of boron causes an increase of 5.61% compared to the undoped HAp sample. The crystallite size was found to be 10.69 ± 1.59 nm for HAp@B, and in the case of HAp@Zn, the size reaches 16.63 ± 1.83 nm, compared to HAp, whose crystallite size value was 19.44 ± 3.13 nm. The mechanical resistance of the samples doped with zinc was the highest and decreased by about 6% after immersion in SBF. Mixing HAp nanoparticles with gypsum improved cell viability compared to HAp for all concentrations (except for 200 µg/mL). Cell density decreased with increasing nanoparticle concentration, compared to gypsum, where the cell density was not significantly affected. The degree of cellular differentiation of osteoblast-type cells was more accentuated in the case of samples treated with G+HAp@B nanoparticles compared to HAp@B. Cell viability in these samples decreased inversely proportionally to the concentration of administered nanoparticles. From the point of view of cell density, this confirmed the quantitative data.

13.
Medicina (Kaunas) ; 59(7)2023 Jul 23.
Artigo em Inglês | MEDLINE | ID: mdl-37512157

RESUMO

The current paper presents a case of a 33-year-old female with an uncommon localization of a leiomyoma in the oral cavity-the anterior palatal fibromucosa and the incisive papilla. The patient referred to the Oro-Maxillo-Facial Surgery Clinic of Emergency City Hospital Timisoara, Romania, complaining of a slight discomfort in the act of mastication and the occurrence and persistence of a diastema between the upper central incisors, due to the presence of a nodule located in the anterior palatal mucosa, between the upper central incisors, without any changes of the subjacent bone structure in the anterior hard palate visible on a cone beam computed tomography image (CBCT). The lesion was removed using a surgical excisional biopsy and a histopathological examination was performed using morphological Hematoxylin-Eosin (HE) staining and additional immunohistochemical (IHC) reactions, in order to confirm the diagnosis. On microscopic examination, bundles of spindle cells were found with eosinophilic cytoplasm and vesicular nuclei, with finely granular chromatin. The immunohistochemical reactions were positive for smooth muscle actin (SMA) and desmin and negative for vimentin. The treatment of choice for leiomyoma of the oral cavity is surgical excision with clear margins, followed by periodical clinical monitoring.


Assuntos
Leiomioma , Feminino , Humanos , Adulto , Leiomioma/diagnóstico , Leiomioma/cirurgia , Palato Duro/patologia , Biópsia , Incisivo/patologia , Tomografia Computadorizada de Feixe Cônico
14.
Dalton Trans ; 52(30): 10386-10401, 2023 Aug 01.
Artigo em Inglês | MEDLINE | ID: mdl-37401566

RESUMO

Two new families of zinc/cobalt/aluminum-based pigments, with a unique composition, were obtained through the polyol method. The hydrolysis process of a mixture of Co(CH3COO)2, Zn(acac)2 and Al(acac)3 (acac- = acetylacetonate ion) in 1,4-butanediol afforded dark blue gels (wPZnxCo1-xAl), in the presence of a supplementary amount of water, and light green powders (PZnxCo1-xAl), respectively, for the water-free procedure (x = 0, 0.2, 0.4). The calcination of the precursors yielded dark green (wZnxCo1-xAl) and blue (ZnxCo1-xAl) products. XRD measurements and Rietveld refinement indicate the co-existence of three spinel phases, in different proportions: ZnxCo1-xAl2O4, Co3O4 and the defect spinel, γ-Al2.67O4. The Raman scattering and XPS spectra are in agreement with the compositions of the samples. The morphology of wZnxCo1-xAl consists of large and irregular spherical particle aggregates (ca. 5-100 mm). Smaller agglomerates (ca. 1-5 mm) with a unique silkworm cocoon-like hierarchical morphology composed of cobalt aluminate cores covered with flake-like alumina shells are formed for ZnxCo1-xAl. TEM and HR-TEM analyses revealed the formation of crystalline, polyhedral particles of 7-43 nm sizes for wZnxCo1-xAl, while for ZnxCo1-xAl, a duplex-type morphology, with small (7-13 nm) and larger (30-40 nm) particles, was found. BET assessment showed that both series of oxides are mesoporous materials, with different pore structures, with the water-free samples exhibiting the largest surface areas due, most likely, to the high percent of aluminum oxide. A chemical mechanism is proposed to highlight the role of the water amount and the nature of the starting compounds in the hydrolysis reaction products and, further, in the morpho-structural features and composition of the resulting spinel oxides. The CIE L*a*b* and C* colorimetric parameters indicate that the pigments are bright, with a moderate degree of luminosity, presenting an outstanding high blueness.

15.
Biomedicines ; 11(6)2023 Jun 14.
Artigo em Inglês | MEDLINE | ID: mdl-37371805

RESUMO

Cervicofacial odontogenic infections can have an aggressive evolution with life-threatening complications. Management in many cases can be a challenge for clinicians, implying an extra focus on individual inflammatory parameters. The aim of this study is to evaluate the evolution of inflammatory markers for the included diagnosed odontogenic cervicofacial phlegmon cases at the moment of hospitalization and after receiving surgical and pharmaceutical treatment. MATERIALS AND METHODS: A total of 39 patients diagnosed with odontogenic cervicofacial phlegmons that were admitted to the Maxillofacial Surgery Department of the Emergency Hospital from Timisoara were included in the study. The main focus was the parameters represented by the systemic immune-inflammatory index (SII) based on neutrophil, platelet, and lymphocytes count; the neutrophil-lymphocyte ratio (NLR); C-reactive protein level (CRP); and white blood cell count (WBC) before and after the treatment as potential prognosis factors. RESULTS: The results of the study after analyzing the included parameters revealed a significant difference between the calculated values of the SII, NLR, CRP, and WBC at admission and at time of discharge, being directly influenced by the treatment. CONCLUSIONS: SII, NLR, CRP, and WBC dynamic changes in severe cervicofacial odontogenic infections can be influenced by receiving accurate surgical and pharmacological treatment, with the potential to become future severity prognosis indexes.

16.
Int J Biol Macromol ; 230: 123162, 2023 Mar 01.
Artigo em Inglês | MEDLINE | ID: mdl-36623620

RESUMO

Due to its inherent properties and wide availability, cellulose acetate is an extremely competitive candidate for the production of polymeric membranes. However, for best results in particular applications, membrane modification is required in order to minimize unwanted interactions and introduce novel characteristics to the pristine polymer. In this study, the surface of commercial cellulose acetate membranes was functionalized with 4'-aminobenzo-15-crown-5 ether, using a covalent bonding approach. The main goal was the improvement of the membranes biomineralization ability, thus making them prospective materials for bone regeneration applications. The proposed reaction mechanism was confirmed by XPS and NMR analysis while the presence of the functionalization agents in the membranes structure was showed by ATR FT-IR and Raman spectra. The effects of the functionalization process on the morphology, thermal and mechanical properties of the membranes were studied by SEM, TGA and tensile tests. The obtained results revealed that the cellulose acetate membranes were successfully functionalized with crown ether and provided a good understanding of the interactions that took place between the polymer and the functionalization agents. Moreover, promising results were obtained during the Taguchi biomineralization studies. SEM images, EDX mapping and XRD spectra indicating that the CA-AB15C5 membranes have a superior Ca2+ ions retention ability, this causing an accentuated calcium phosphate deposition on the modified polymeric fibers, compared to the neat CA membrane.


Assuntos
Éteres de Coroa , Osseointegração , Espectroscopia de Infravermelho com Transformada de Fourier , Polímeros/química , Membranas Artificiais
17.
Pharmaceutics ; 14(12)2022 Nov 28.
Artigo em Inglês | MEDLINE | ID: mdl-36559114

RESUMO

Natural polymers have shown tremendous potential towards the development of hydrogels with tissue regeneration properties. Among them, chitosan and dextran are polysaccharides widely applied in the wound dressing area owing to their mucoadhesiveness, biodegradability, hemostatic potential, and intrinsic antibacterial activity, while glycerol is a well-known biocompatible solvent extensively used in the manufacture of cosmetic, pharmaceutical, medical, and personal care products. In order to enhance the properties of natural polymer-based hydrogels, the focus has currently shifted towards the addition of nanomaterials with antibacterial and regenerative potential, i.e., iron oxide nanoparticles. Thus, the aim of the present study was to develop a series of chitosan-dextran-glycerol hydrogels loaded with iron oxide nanoparticles, either readily added or formed in situ. The physicochemical properties of the so obtained hydrogels demonstrated an improved dispersibility of the in situ formed magnetite nanoparticles, which further decreases the porosity and swelling ratio of the hydrogels but increases the antimicrobial properties. Additionally, the presence of glycerol enhances the cell viability but reduces the antimicrobial potential. In this context, the results proved promising biological and antimicrobial properties, thus confirming their potential as biomaterials for wound healing and regeneration.

18.
Materials (Basel) ; 15(19)2022 Oct 06.
Artigo em Inglês | MEDLINE | ID: mdl-36234283

RESUMO

Due to the urgent need to develop and improve biomaterials, the present article proposes a new strategy to obtain porous scaffolds based on forsterite (Mg2SiO4) for bone tissue regeneration. The main objective is to restore and improve bone function, providing a stable environment for regeneration. The usage of magnesium silicate relies on its mechanical properties being superior to hydroxyapatite and, in general, to calcium phosphates, as well as its high biocompatibility, and antibacterial properties. Mg2SiO4 powder was obtained using the sol-gel method, which was calcinated at 800 °C for 2 h; then, part of the powder was further used to make porous ceramics by mixing it with a porogenic agent (e.g., sucrose). The raw ceramic bodies were subjected to two sintering treatments, at 1250 or 1320 °C, and the characterization results were discussed comparatively. The porogenic agent did not influence the identified phases or the samples' crystallinity and was efficiently removed during the heat treatment. Moreover, the effect of the porogenic agent no longer seems significant after sintering at 1250 °C; the difference in porosity between the two ceramics was negligible. When analysing the in vitro cytotoxicity of the samples, the ones that were porous and treated at 1320 °C showed slightly better cell viability, with the cells appearing to adhere more easily to their surface.

19.
Materials (Basel) ; 15(20)2022 Oct 21.
Artigo em Inglês | MEDLINE | ID: mdl-36295468

RESUMO

The paper presents experimental results regarding the synthesis of Portland clinker starting from raw mixes based on two types of clayey precursors, i.e., clay and marl (the most common types of raw materials used in the cement industry), with and without glass waste content. The soda-lime glass waste addition (5.36-5.59 wt %), used to control the silica ratio of the raw mix, improved the raw mix burnability and decreased the calcination temperature (by 20 °C), leading to a decrease in fuel consumption and contributing to the reduction in CO2 emissions associated with clinker and cement production. The clinkers obtained by the calcination of raw mixes with glass waste content at 1430 °C with a 30 min plateau had a similar mineralogical composition and microstructure to the clinkers obtained from the reference raw mixes and fulfilled the requirements of the specific standard EN 197-1. The obtained clinkers were used to produce two types of Portland cement, i.e., a unitary cement (CEM I) and a binary blended cement with slag (CEM II/B-S). The main characteristics of these cements, i.e., loss on ignition, insoluble residue, sulfate and chloride contents, as well as the setting time and soundness, meet the conditions stipulated in the EN 197-1 standard. The values of compressive strength, assessed on mortars after 2, 7 and 28 days of curing, allow the classification of all CEM I cements in the 42.5 R class. In the case of CEM II/B-S cements, those obtained from raw mixes with clay can be classified in the 42.5 N class, while those obtained from raw mixes with marl are classified in the 32.5 R class.

20.
Nanomaterials (Basel) ; 12(17)2022 Aug 30.
Artigo em Inglês | MEDLINE | ID: mdl-36080042

RESUMO

IV-VI semiconductor quantum dots embedded into an inorganic matrix represent nanostructured composite materials with potential application in temperature sensor systems. This study explores the optical, structural, and morphological properties of a novel PbS quantum dots (QDs)-doped inorganic thin film belonging to the Al2O3-SiO2-P2O5 system. The film was synthesized by the sol-gel method, spin coating technique, starting from a precursor solution deposited on a glass substrate in a multilayer process, followed by drying of each deposited layer. Crystalline PbS QDs embedded in the inorganic vitreous host matrix formed a nanocomposite material. Specific investigations such as X-ray diffraction (XRD), optical absorbance in the ultraviolet (UV)-visible (Vis)-near infrared (NIR) domain, NIR luminescence, Raman spectroscopy, scanning electron microscopy-energy dispersive X-ray (SEM-EDX), and atomic force microscopy (AFM) were used to obtain a comprehensive characterization of the deposited film. The dimensions of the PbS nanocrystallite phase were corroborated by XRD, SEM-EDX, and AFM results. The luminescence band from 1400 nm follows the luminescence peak of the precursor solution and that of the dopant solution. The emission of the PbS-doped film in the NIR domain is a premise for potential application in temperature sensing systems.

SELEÇÃO DE REFERÊNCIAS
DETALHE DA PESQUISA