ABSTRACT
Force-distance curves between atomic force microscopy (AFM) tip (Si3N4 non-functionalized) and bovine serum Albumin (BSA) immobilized on Si3N4 substrates have been performed with the purpose to understand how multiple interactions between the protein and the tip were favored in different pHs (4, 6 and 10). In this work, 100 silicon wafer samples were used to deposit a layer of Si3N4. Protein immobilization consisted of the silanization of the substrates with 3-aminopropyltriethoxysilane (APTES) and crosslinking with glutaraldehyde (GA). All functionalization steps were evaluated by contact angle, X-Ray electron spectroscopy (XPS) and AFM. AFM images showed increase of roughness following functionalization. At pH 4, it was possible to note that small forces (49.1⯱â¯2.4â¯pN) were needed to stretch BSA, with a contour length of CLâ¯=â¯(30.0⯱â¯1.1â¯nm). At pH 6, the force applied was higher (101.5⯱â¯5.0â¯pN) with a higher molecule stretch CLâ¯=â¯(75.6⯱â¯3.8â¯nm) because the pH is close to the BSA isoelectric point where the folding of the protein is favored as surfaces charges are minimized leading to lower attractive intramolecular forces. Young's Modulus were also calculated and the lowest value (265â¯kPa) was observed at pH 10.
Subject(s)
Glutaral/chemistry , Propylamines/chemistry , Serum Albumin, Bovine/chemistry , Silanes/chemistry , Silicon Compounds/chemistry , Adsorption , Animals , Cattle , Hydrogen-Ion Concentration , Microscopy, Atomic Force , Photoelectron Spectroscopy , Protein Binding , Serum Albumin, Bovine/metabolism , Silicon Compounds/metabolism , Surface PropertiesABSTRACT
The aim of this study was to evaluate the physicochemical characteristics of 3 mineralized bovine inorganic biomaterials and correlate them with the dissolution rate. Bio-Oss(r), GenoxInorgânico(r), and Bonefill(r) were examined using field emission gun scanning electron microscopy (FEG-SEM), Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), specific surface area (BET), calcium/phosphorous molar ratio and a dissolution assay. Bio-Oss(r) showed a micro- and nanoporous structure consisting of 15-nm hydroxyapatite (HA) crystallites; Genox(r), a microporous structure composed of 39-nm HA crystallites; and Bonefill(r), micro- and nanoporous structure of indeterminable crystallite size. FTIR analysis showed that Bio-Oss(r) and Genox(r) were composed of calcium phosphate. The absorption bands of phosphate were poorly defined in Bonefill(r). By XRD, Bio-Oss(r) was shown to contain peaks related to the carbonated HA, whereas Genox(r) only contained peaks corresponding to HA. The broad bands in Bonefill(r) indicated low crystallinity. Bio-Oss(r) showed a greater surface area and calcium release rate than that of Genox(r). Although all biomaterials were of bovine origin, the different manufacturing processes result in materials with different physicochemical properties and may influence the biological and clinical response.
Subject(s)
Bone Transplantation , Animals , Cattle , Crystallography, X-Ray , Microscopy, Electron, Scanning , Spectroscopy, Fourier Transform InfraredABSTRACT
The aim of this study was to evaluate the physicochemical characteristics of 3 mineralized bovine inorganic biomaterials and correlate them with the dissolution rate. Bio-Oss(r), GenoxInorgânico(r), and Bonefill(r) were examined using field emission gun scanning electron microscopy (FEG-SEM), Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), specific surface area (BET), calcium/phosphorous molar ratio and a dissolution assay. Bio-Oss(r) showed a micro- and nanoporous structure consisting of 15-nm hydroxyapatite (HA) crystallites; Genox(r), a microporous structure composed of 39-nm HA crystallites; and Bonefill(r), micro- and nanoporous structure of indeterminable crystallite size. FTIR analysis showed that Bio-Oss(r) and Genox(r) were composed of calcium phosphate. The absorption bands of phosphate were poorly defined in Bonefill(r). By XRD, Bio-Oss(r) was shown to contain peaks related to the carbonated HA, whereas Genox(r) only contained peaks corresponding to HA. The broad bands in Bonefill(r) indicated low crystallinity. Bio-Oss(r) showed a greater surface area and calcium release rate than that of Genox(r). Although all biomaterials were of bovine origin, the different manufacturing processes result in materials with different physicochemical properties and may influence the biological and clinical response.
O objetivo deste estudo foi avaliar as características físico-químicas de 3 biomateriais bovinos inorgânicos mineralizados e correlacioná-los com a taxa de dissolução. Bio-Oss(r), Genox Inorgânico(r) e Bonefill(r) foram caracterizados por microscopia eletrônica de varredura com fonte de emissão por efeito de campo (MEV-FEG), espectroscopia de infravermelho com transformada de Fourier (FTIR), difração de raios-X (DRX), área superficial específica (BET), razão molar cálcio/fósforo e análise da dissolução. Bio-Oss(r) mostrou uma estrutura micro e nanoporosa consistindo de cristalitos de hidroxiapatita (HA) de 15 nm; Genox(r), uma estrutura microporosa composta de cristalitos de HA de 39 nm e Bonefill(r), estrutura micro e nanoporosa com tamanho indeterminável de cristalito. Análises de FTIR mostraram que Bio-Oss(r) e Genox(r) eram compostos por fosfato de cálcio. As bandas de absorção de fosfato encontraram-se pouco definidas no Bonefill(r). Por DRX, Bio-Oss(r) mostrou picos relacionados à HA carbonatada, enquanto Genox(r) somente apresentou picos correspondentes à HA; as bandas alargadas no Bonefill(r) indicaram baixa cristalinidade. Bio-Oss(r) apresentou maior área de superfície e taxa de liberação de cálcio quando comparado ao Genox(r). Embora todos os biomateriais fossem de origem bovina, os diferentes processos de manufatura resultam em materiais com diferentes propriedades físico-químicas e podem influenciar a resposta biológica e clínica.
Subject(s)
Animals , Cattle , Bone Transplantation , Crystallography, X-Ray , Microscopy, Electron, Scanning , Spectroscopy, Fourier Transform InfraredABSTRACT
In this study Ti-6Al-4V samples were used as substrates and Ca-P layers were deposited using sol-gel technique and covered by spin-coating. The efficiency of hydroxyapatite (HA) coatings as drug carrier was also evaluated by immersion in gentamicin sulphate solution and the release profiles were obtained by cumulative method of the coating samples. Three non-linear mathematical methods were employed in order to discuss a possible mechanism to lead the drug release. Physical chemical techniques showed the presence of the typical absorption bands of calcium phosphates by infrared spectroscopy while X-ray diffraction peaks matched up with hydroxyapatite patterns. Microstructural techniques (SEM, EDS) help to confirm the hydroxyapatite coating by surface aspect and Ca/P ratio (1.64). The best fitting according statistical results explained each stage of the released profiles and correspond to a mixture of short initial burst effect plus drug dissolution with a specific kinetic and the diffusion of the gentamicin solid particles.
Subject(s)
Coated Materials, Biocompatible/chemistry , Drug Carriers/chemistry , Gentamicins/administration & dosage , Gentamicins/chemistry , Hydroxyapatites/chemistry , Titanium/chemistry , Alloys , Anti-Bacterial Agents/administration & dosage , Anti-Bacterial Agents/chemistry , Diffusion , Materials Testing , Phase TransitionABSTRACT
Cell-titanium interactions are crucial to the clinical success of bone and dental implants. The physico-chemical characteristics of the substrates surface influence osteoblast proliferation, differentiation, and activity as well. The osteoblast behavior was analyzed on three different titanium surfaces: ground with an abrasive 600 grit SiC paper, blasted with alumina particles (65 microm diameter) and alumina blasted followed by a double chemical etch (4% HF+4% HF/8% H2O2). Scanning electron microscopy (SEM) and profilometry showed distinct microtopographies. Ground samples showed parallel-groove orientation. The Al2O3-blasted surface presented the roughest microtopography with aluminum-rich particles incrusted in the titanium surface. Osteoblasts cells from femora of Balb/c mice were seeded onto the substrates tested. Cell morphology and initial attachment were evaluated by SEM. Osteoblasts adhered to and spread on all samples tested. However, on rough surfaces, osteoblasts did not spread completely and acquired a polygonal morphology. Besides, the cell proliferation rate was diminished at the beginning of incubation on rough surfaces. Our results suggest a delay, rather than an impairment, in osteoblast viability and alkaline phosphatase activity when cells are cultured on rough surfaces, inducing a distinct osteoblast phenotype, rather than blocking its activity. At least in the culture conditions used in this work, alumina particles did not affect osteoblast behavior.
Subject(s)
Osteoblasts/physiology , Titanium , Aluminum Oxide , Animals , Cell Adhesion , Cell Differentiation , Cell Movement , Cell Proliferation , Cell Shape , Cell Survival , Cells, Cultured , Coated Materials, Biocompatible , Dental Etching , Dental Polishing , Mice , Mice, Inbred BALB C , Microscopy, Electron, Scanning , Osteoblasts/cytology , Surface PropertiesABSTRACT
In the complex process of bone formation at the implant-tissue interface, surface properties are relevant factors modulating osteoblastic function. In this study, commercially pure titanium (cp Ti) samples were prepared with different surface characteristics using chemical attack with a sulfuric acid/hydrochloric acid based solution (treatment A); chemical attack plus anodic oxidation using phosphoric acid (treatment B); and chemical attack plus thermal oxidation followed by immersion in a sodium fluoride solution (treatment C). The samples were characterized by scanning electron microscopy (SEM), contact profilometry and contact angle. The biological performance of the prepared surfaces was evaluated using mice osteoblastic cell cultures for up to 21 days. Cells seeded on the different titanium samples showed similar behavior during cell attachment and spreading. However, cellular proliferation and differentiation were higher for samples submitted to treatments A and C (p < or = 0.05; n = 3), which were less rough and showed surface free energy with smaller polar components.
Subject(s)
Dental Materials/chemistry , Osteoblasts/physiology , Titanium/chemistry , Animals , Biocompatible Materials/chemistry , Cell Differentiation , Cell Proliferation , Cell Survival , Hydrochloric Acid/pharmacology , Mice , Osteoblasts/drug effects , Oxidation-Reduction , Phosphoric Acids/pharmacology , Sodium Fluoride/pharmacology , Sulfuric Acids/pharmacology , Surface Properties/drug effects , Titanium/pharmacologyABSTRACT
No complexo processo de formação óssea na interface implante-osso, as propriedades de superfície são um importante fator modulador da função osteoblástica. No presente estudo, foram preparadas amostras de titânio comercialmente puro (cp Ti) com diferentes propriedades de superfície por meio de ataque químico com solução à base de ácido sulfúrico/clorídrico (tratamento A); ataque químico seguido de oxidação anódica com ácido fosfórico (tratamento B); e ataque químico seguido de oxidação térmica e imersão em fluoreto de sódio (tratamento C). As chapas foram caracterizadas por meio de microscopia eletrônica de varredura (MEV), perfilometria e ângulo de contato. O comportamento de células osteoblásticas de camundongo foi acompanhado por três semanas. As células cultivadas sobre os diferentes substratos de titânio apresentaram um modelo de comportamento similar durante as etapas de adesão e espalhamento. No entanto, a proliferação e a diferenciação celulares foram maiores nas amostras submetidas aos tratamentos A e C, que se apresentaram menos rugosas e com energia livre de superfície com menores componentes polares.
Subject(s)
Mice , Animals , Dental Materials/chemistry , Osteoblasts/physiology , Titanium/chemistry , Biocompatible Materials/chemistry , Cell Differentiation , Cell Proliferation , Cell Survival , Hydrochloric Acid/pharmacology , Oxidation-Reduction , Osteoblasts/drug effects , Phosphoric Acids/pharmacology , Sodium Fluoride/pharmacology , Sulfuric Acids/pharmacology , Surface Properties/drug effects , Titanium/pharmacologyABSTRACT
Foram preparadas amostras de chapas de titânio com nove condiçöes de superfície, sendo três lixadas até lixa 600 e seis jateadas com óxido de alumínio (alumina com granulometria 65mm e 250mm). Seis condiçöes foram entäo submetidas a tratamento ácido com soluçäo de ácido sulfúrico/clorídico ou soluçäo contendo ácido fluorídrico. Essas superfícies foram caracterizadas por meio de técnicas, como microscopia eletrônica de varredura (MEV/EDS), espectroscopia de fotoelétrons por raio X (XPS) e medidas de rugosidade média. A soluçäo contendo ácido fluorídrico foi eletiva na remoçäo das partículas de alunina, provenientes do jateamento mecânico, e na criaçäo de uma microscopia homogeneamente rugorosa
