RESUMO
A safe and effective use of nanoparticles in biology and medicine requires a thorough understanding, down to the molecular level, of how nanoparticles interact with cells in the physiological environment. This study evaluated the two-way interaction between inorganic nanomaterials (INMs) and cells from A549 human lung carcinoma cell line. The interaction between silica and zinc oxide INMs and cells was investigated using both standard methods and advanced characterization techniques. The effect of INMs on cell properties was evaluated in terms of cell viability, chemical modifications, and volume changes. The effect of cells and culture medium on INMs was evaluated using dynamic light scattering (DLS), scanning electron microscopy and energy-dispersive X-ray spectroscopy (SEM-EDS), high performance liquid chromatography (HPLC), gas chromatography-mass spectroscopy (GC-MS), Fourier transform infrared spectroscopy (FTIR), and thermogravimetric analysis (TGA). No cytotoxic effect was detected in the case of silicon oxide INMs, while for high doses of zinc oxide INMs a reduction of cell survival was observed. Also, increased cell volume was recorded after 24 h incubation of cells with zinc oxide INMs. A better dimensional homogeneity and colloidal stability was observed by DLS for silicon oxide INMs than for zinc oxide INMs. SEM-EDS analysis showed the effectiveness of the adopted dispersion procedure and confirmed in the case of zinc oxide INMs the presence of residual substances derived from organosilane coating. HPLC and GC-MS performed on INMs aqueous dispersions after 24 h incubation showed an additional peak related to the presence of an organic contaminant only in the case of zinc oxide INMs. FTIR Chemical Imaging carried out directly on the cells showed, in case of incubation with zinc oxide INMs, a modification of the spectra in correspondence of phospholipids, nucleic acids and proteins characteristic absorption bands when compared with untreated cells. Overall, our results confirm the importance of developing new experimental methods and techniques for improving the knowledge about the biosafety of nanomaterials.
Assuntos
Sobrevivência Celular/efeitos dos fármacos , Nanopartículas/toxicidade , Células A549 , Tamanho Celular/efeitos dos fármacos , Humanos , Espectroscopia de Infravermelho com Transformada de FourierRESUMO
Fricke gel radiochemical sensors based on various matrices have been studied for decades as 3D dosimeters for radiotherapy. Despite their many appealing features, progressive aging and blurring of the signal have prevented the widespread use of these dosimeters, so far. We have addressed these shortcomings and hereby present our development of a Fricke gel based on a chemically cross-linked PVA matrix. We investigated the influence of several parameters of the polymeric matrix on sensitivity, diffusion coefficient and spontaneous oxidation of the proposed gel dosimeter. Based on these findings, we optimized the gel compositions. Our new gel formulation combines transparency, high sensitivity and simple production method, typical of gels based on natural polymers, with low diffusion coefficient and slow spontaneous oxidation typical of PVA gels made by freezing-thawing.
Assuntos
Géis/química , Glutaral/química , Polivinil/química , Dosímetros de Radiação , Reagentes de Ligações Cruzadas/química , Radiometria/instrumentação , Radiometria/métodosRESUMO
The purpose of this study was the design and preliminary feasibility study of an advanced temporary hip prosthesis acting as an in-site drug dispensing system. An interactive device was designed to improve the recovery of bone infections compared to the mechanical spacers currently used in septic mobilizations. A commercial device was chosen and modified specifically for the purpose. First of all, the device was provided with a hydraulic multi-channel system connected via catheter to a subcutaneous valve, refillable with a drug aqueous solution from the outside. Moreover, since it allows samples of biological fluids for analyses to be drawn directly from the implantation site, this chemical dispensing system was designed to allow the course of infections to be monitored and customized therapies to be dosed. The insertion of biocompatible membranes inside the channel ends was considered essential to prevent their occlusion by fibrous tissue growth, thereby preserving the device functionality. Moreover, a biodegradable spongy ring was designed to be fixed onto the stem in distal position both to give primary stability to the implant and to act simultaneously as a scaffold for bonelike cell growth.
Assuntos
Prótese de Quadril , Bombas de Infusão Implantáveis , Desenho de Prótese , Implantes Absorvíveis , Materiais Biocompatíveis/química , Humanos , Infecções Relacionadas à Prótese/tratamento farmacológicoRESUMO
Tissue regeneration with autologous cell transplantation is one of the most important goals in clinical research. In this field, the development of bioactive materials that provide microenvironments for cell-matrix interactions mimicking biological conditions is required. In recent years, many synthetic materials have been developed as scaffolds and many procedures for the surface modification of these materials have been applied using biological molecules. In this study, we analyzed the morphology and the molecule production by ovine embryonic lung fibroblasts cultured on three different sponge-like matrices based on poly(L-lactic acid) (PLLA): agarose/PLLA, crosslinked and uncrosslinked gelatin/PLLA. The matrices were produced by using an emulsion freeze-drying method leading to the formation of sponge-like materials with high porosity and with interconnection between the pores. In vitro MTT test demonstrated that transplanted cells were viable and metabolically active. Morphological analysis revealed that fibroblasts adhered to and penetrated the polymeric structures. Moreover, all the different matrices supported fibroblast production of proteoglycans, glycoproteins, and matrix molecules such as elastin, collagen I, and fibronectin. These data suggest that the tested bioactive scaffolds may support the growth and extracellular matrix molecule production of fibroblasts allowing in vitro connective tissue regeneration.
Assuntos
Pulmão/embriologia , Engenharia Tecidual , Animais , Materiais Biocompatíveis , Transplante de Células , Células Cultivadas , Colágeno Tipo I/metabolismo , Elastina/metabolismo , Fibroblastos/citologia , Fibroblastos/metabolismo , Humanos , Ácido Láctico , Pulmão/citologia , Pulmão/metabolismo , Teste de Materiais , Microscopia Eletrônica de Varredura , Poliésteres , Polímeros , Regeneração , OvinosRESUMO
In order to overcome the biological deficiencies of synthetic polymers and to enhance the mechanical characteristics of natural polymers, two synthetic polymers, poly(vinyl alcohol) (PVA) and poly(acrylic acid) (PAA) were blended, in different ratios, with two biological polymers, collagen (C) and hyaluronic acid (HA). These blends were used to prepare films, sponges and hydrogels which were loaded with growth hormone (GH) to investigate their potential use as drug delivery systems. The GH release was monitored in vitro using a specific enzyme-linked immunosorbent assay. The results show that GH can be released from HA/PAA sponges and from HA/PVA and C/PVA hydrogels. The initial GH concentration used for sample loading affected the total quantity of GH released but not the pattern of release. The rate and quantity of GH released was significantly dependent on the HA or C content of the polymers.
Assuntos
Resinas Acrílicas/química , Colágeno/química , Sistemas de Liberação de Medicamentos/normas , Hormônio do Crescimento/administração & dosagem , Ácido Hialurônico/química , Álcool de Polivinil/química , Resinas Acrílicas/metabolismo , Animais , Fenômenos Biomecânicos , Biopolímeros , Colágeno/metabolismo , Preparações de Ação Retardada , Géis/química , Hormônio do Crescimento/metabolismo , Humanos , Ácido Hialurônico/metabolismo , Microscopia Eletrônica de Varredura , Álcool de Polivinil/metabolismo , Proteínas Recombinantes/metabolismo , Proteínas Recombinantes/farmacocinéticaRESUMO
A range of 'bioartificial' collagen/poly(vinyl alcohol) blends have been produced, cast as films and cross-linked using either glutaraldehyde or a dehydrothermal treatment (DHT). Films were used as substrates for the culture of osteoblast-like cells. The attachment, adhesion and proliferative responses of these cells to the range of films were examined using proliferation assays, light, electron and confocal microscopy. There was an inverse relationship between collagen content of gluataraldehyde cross-linked films and the extent of cell proliferation on them. A cytotoxicity assay demonstrated no toxic effect related to increasing collagen content. The greatest differences in cell responses observed were associated with the choice of cross-linking method. Films cross-linked with glutaraldehyde showed variation related to collagen content in cell adhesion, proliferation and morphology. Such differences were not apparent with the DHT cross-linked films. Collagen/PVA 'bioartificial' films can be dehydrothermally cross-linked to increase biological stability and reduce water solubility. The method of cross-linking employed is the greater influence in determining osteoblast compatibility with these materials. The DHT cross-linking method is a preferable alternative to the use of glutaraldehyde. Collagen/PVA bioartificial films cross-linked by the DHT method have shown potential for biocompatibility with osteoblasts.
Assuntos
Materiais Biocompatíveis/farmacologia , Colágeno/farmacologia , Reagentes de Ligações Cruzadas/farmacologia , Osteoblastos/efeitos dos fármacos , Álcool de Polivinil/farmacologia , Materiais Biocompatíveis/química , Materiais Biocompatíveis/toxicidade , Divisão Celular/efeitos dos fármacos , Células Cultivadas , Colágeno/química , Colágeno/toxicidade , Reagentes de Ligações Cruzadas/química , Glutaral/química , Humanos , Microscopia Confocal , Microscopia Eletrônica , Osteoblastos/citologia , Álcool de Polivinil/química , Álcool de Polivinil/toxicidade , Propriedades de SuperfícieRESUMO
Bioartificial polymeric materials, based on blends of biological and synthetic polymers, have been proposed as new materials for applications in the biomedical field. They should usefully combine the biocompatibility of the biological component with the physical and mechanical properties of the synthetic component. Blends of collagen with either poly(vinyl alcohol) or poly(acrylic acid) have been prepared by mixing aqueous solutions of the two polymers. Differential scanning calorimetry and dynamic mechanical thermal analysis has been carried out to investigate the miscibility properties of the polymers and the mechanical behaviour of the blends.
Assuntos
Resinas Acrílicas/química , Materiais Biocompatíveis/química , Colágeno/química , Álcool de Polivinil/química , Varredura Diferencial de Calorimetria , Fenômenos Químicos , Físico-Química , Solubilidade , Água/químicaRESUMO
Fiber mesh scaffolds were recently investigated in tissue engineering as possible support for stem cell growth and differentiation, in order to repair lesion areas in clinical practice. In particular, the literature is focused on fiber mesh scaffolds constituted of biocompatible and resorbable polymeric structures, like poly(L-lactic acid) (PLLA). However, as regards the study of constructs constituted of PLLA microfibers and cells, only quantitative and SEM analyses were reported, lacking histological analysis. Histological evaluation of these constructs could give important information about cellular distribution in the scaffold, cell-scaffold interactions and extracellular matrix production. The purpose of our study was to find a valid method to analyze PLLA microfiber/cell constructs from both histological and histochemical angles. Biodegradable non-woven fiber meshes were prepared using hollow microfibers, based on PLLA. We first evaluated different embedding methods useable for histological analysis and the results showed that among the paraffin, Killik, and acrylic resin the only suitable medium was the latter. Then we employed the acrylic resin to embed the constructs made up of PLLA microfibers and bone marrow-derived human mesenchymal stromal cells, which we then analyzed with Toluidine Blue, PAS and Alcian Blue staining. These constructs, previously analyzed for cell viability by MTT and CCK-8 tests, showed viable/proliferating cells until 6 weeks of culture. The stainings performed on constructs confirmed viability data obtained with SEM and MTT/CCK-8 and supplied other information on the cell behaviors such as the distribution and organization onto the scaffold and the production of extracellular matrix molecules. In conclusion, this methodological study mainly suggests a suitable method to analyze PLLA microfiber/cell constructs, at the same time confirming and enriching the literature data on the compatibility between PLLA microfibers and hMSCs.
Assuntos
Materiais Biocompatíveis/química , Histocitoquímica/métodos , Ácido Láctico/química , Células-Tronco Mesenquimais/citologia , Células-Tronco Mesenquimais/metabolismo , Polímeros/química , Engenharia Tecidual/métodos , Proliferação de Células , Sobrevivência Celular , Humanos , Microscopia Eletrônica de Varredura , Poliésteres , Sais de Tetrazólio/metabolismo , Tiazóis/metabolismoRESUMO
The release of human growth hormone (GH) from bioartificial polymeric materials in the form of hydrogels, was measured in vitro for up to 3 weeks. Poly(vinyl-alcohol) (PVA) was blended, in different ratios, with two biological polymers, dextran and chitosan respectively. These blends were used to prepare hydrogels, using a freeze-thawing method. The hydrogels were loaded with GH, and their potential use as delivery systems was investigated. The release with time of PVA, in aqueous medium, was also monitored and evaluated. Scanning electron microscopy was used to investigate the structure of the hydrogels. The results obtained indicated that GH can be released from both dextran/PVA and chitosan/PVA hydrogels. The initial GH concentration used for sample loading affected the total quantity of GH released but not the pattern of release. The amount of GH released was affected by the content of the biological component. The percentage of PVA released was low but it was, however, related to the content of chitosan and dextran in the blends.
RESUMO
Hydrogels are three-dimensional polymeric networks very similar to biological tissues and potentially useful as drug delivery systems. Poly(vinyl alcohol)-based hydrogels containing different amounts of dextran or chitosan were prepared using the freezing-thawing method. Repeated freezing-thawing cycles of a poly(vinyl alcohol) (PVA) aqueous solution lead to the formation of crystallites which act as cross-linking sites, and a hydrogel with a high capacity to swell is obtained. The effects of the two different polysaccharides on the properties of the obtained materials were investigated by differential scanning calorimetry, dynamic mechanical analysis and scanning electron microscopy. In addition the release with time of poly(vinyl alcohol) in aqueous medium, was monitored and evaluated. On the basis of the obtained results it seems that the presence of dextran favors the crystallization process of PVA, allowing the formation of a more ordered and homogeneous structure. Instead, chitosan seems to perturb the formation of PVA crystallites leading to a material with a less regular structure.
RESUMO
In vitro cytotoxicity (Neutral Red uptake, Kenacid Blue and MTT) and cytocompatibility (cell adhesion and proliferation) tests were applied to the biocompatibility study of a series of poly(ester-ether-ester) block copolymers of potential interest as biomaterials. Our results indicate that the copolymer extracts after 72 hours incubation with a 3T3 mouse fibroblast cell line do not induce significant toxic effects. Furthermore, human umbilical vein endothelial cells seeded on thin copolymer films show a normal pattern of growth. We conclude that thein vitro tests used are a valid instrument to evaluate the potential toxic action of synthetic materials on different cell compartments and that the tested materials seem to be promising for future applications in the field of biomedical devices.
RESUMO
In vitro cytotoxicity (Neutral Red uptake, Kenacid Blue and MTT) and cytocompatibility (cell adhesion and proliferation) tests were applied to the biocompatibility study of a series of poly(ester-ether-ester) block copolymers of potential interest as biomaterials. Our results indicate that the copolymer extracts after 72 hours incubation with a 3T3 mouse fibroblast cell line do not induce significant toxic effects. Furthermore, human umbilical vein endothelial cells seeded on thin copolymer films show a normal pattern of growth. We conclude that the in vitro tests used are a valid instrument to evaluate the potential toxic action of synthetic materials on different cell compartments and that the tested materials seem to be promising for future applications in the field of biomedical devices.
Assuntos
Materiais Biocompatíveis/toxicidade , Teste de Materiais/métodos , Células 3T3/efeitos dos fármacos , Animais , Biotecnologia , Morte Celular/efeitos dos fármacos , Células Cultivadas , Endotélio Vascular/efeitos dos fármacos , Camundongos , Polímeros/toxicidadeRESUMO
Bioartificial polymeric materials, based on blends of polysaccharides with synthetic polymers such as poly(vinyl alcohol) (PVA) and poly(acrylic acid) (PAA), were prepared as films or hydrogels. The physico-chemical, mechanical, and biological properties of these materials were investigated by different techniques such as differential scanning calorimetry, dynamic mechanical thermal analysis, scanning electron microscopy, and in vitro release tests, with the aim of evaluating the miscibility of the polymer blends and to establish their potential applications. The results indicate that while dextran is perfectly miscible with PAA, dextran/PVA, chitosan/PVA, starch/PVA, and gellan/PVA blends behave mainly as two-phase systems, although interactions can occur between the components. Cross-linked starch/PVA films could be employed as dialysis membranes: they showed transport properties comparable to, and in some cases better than, those of currently used commercial membranes. Hydrogels based on dextran/PVA and chitosan/PVA blends could find applications as delivery systems. They appeared able to release physiological amounts of human growth hormone, offering the possibility to modulate the release of the drug by varying the content of the biological component.
Assuntos
Materiais Biocompatíveis/química , Polímeros/química , Polissacarídeos/química , Transporte Biológico , Calorimetria , Quitina/análogos & derivados , Quitina/química , Quitosana , Dextranos/química , Temperatura Alta , Hormônio do Crescimento Humano/química , Humanos , Hidrogel de Polietilenoglicol-Dimetacrilato/química , Microscopia Eletrônica de Varredura , Polissacarídeos Bacterianos/química , Amido/química , TemperaturaRESUMO
An electron spectroscopy for Chemical Analysis (ESCA) characterization of films based on collagen-poly(vinylalcohol) blends, cross-linked by dehydrothermal treatment is reported. The semiquantitative analysis indicates a remarkable enrichment of collagen in the surface with respect to its initial percentage utilized to prepare the blends.
Assuntos
Materiais Biocompatíveis/química , Colágeno/metabolismo , Cloreto de Polivinila/química , Animais , Materiais Biocompatíveis/metabolismo , Bovinos , Colágeno/química , Reagentes de Ligações Cruzadas , Glicina/metabolismo , Hidroxiprolina/metabolismo , Microscopia Eletrônica , Polímeros , Cloreto de Polivinila/metabolismo , Prolina/metabolismo , Software , Propriedades de SuperfícieRESUMO
Thin films of both pure soluble collagen (CLG) and poly(vinylalcohol) (PVA) and mixtures of the two, ranging from 20-80% PVA composition were studied to test the effects of PVA content and of glutaraldehyde vapour cross-linking. Both the thermal and mechanical behavior and, in addition, proteolytic stability were clearly influenced by the ratio of CLG/PVA. The experimental results indicate that no thermodynamic compatibility occurs between the two homopolymers. However, there is evidence that strong interactions, probably due to hydrogen bond formation, occur between the biological and synthetic polymers. The interactions appear stronger in those films with a lower PVA content and which were not cross-linked. Both the thermal and biological stability are increased and there is an improvement of the mechanical properties. The mutual intermolecular influence appears to allow the attainment of a good mechanical compatibility between CLG and PVA.