Potential Biomedical Materials Research Articles

Preliminary viability studies of fibroblastic cells cultured on microcrystalline and nanocrystalline diamonds produced by chemical vapour deposition method

Implant materials used in orthopedics surgery have demonstrated some disadvantages, such as metallic corrosion processes, generation of wear particles, inflammation reactions and bone reabsorption in the implant region. The diamond produced through hot-filament chemical vapour deposition method is a new potential biomedical material due to its chemical inertness, extreme hardness and low coefficient of friction. In the present study we analysis two samples: the microcrystalline diamond and the nanocrystalline diamond. The aim of this study was to evaluate the surface properties of the diamond samples by scanning electron microscopy, Raman spectroscopy and atomic force microscopy. Cell viability and morphology were assessed using thiazolyl blue tetrazolium bromide, cytochemical assay and scanning electron microscopy, respectively. The results revealed that the two samples did not interfere in the cell viability, however the proliferation of fibroblasts cells observed was comparatively higher with the nanocrystalline diamond.

Influence of Microwave Plasma Nitriding on Hemocompatibility of Biomedical Stainless Steels

During nitriding treatment between 350°C and 550°C, the phase transformation sequence on the nitrided layers of the alloys was found to be γ → (γ + γN) → (γ + α+ CrN). The hemocompatibility test demonstrated the nitrided layer processed the excellent hemocompatibility properties. These results could be useful in further understanding the clinical mechanismsof thenitrided alloys, to develop as a potential biomedical material.

In vivo preliminary evaluation of bone-microcrystalline and bone-nanocrystalline diamond interfaces

Chemical vapor deposited diamond is a new potential biomedical material which has the advantage of chemical inertness, extreme hardness and low coefficient of friction, among others. In orthopedics and maxillofacial surgery, these properties could improve implant performance, reducing metallic corrosion, particle wear, inflammatory reactions and bone loss. In the present study, two types of chemical vapor deposition (CVD) diamonds have been analyzed: microcrystalline diamonds (MD) and nanocrystalline diamonds (ND), both produced by hot-filament chemical vapor deposition. The diamond tubes were previously characterized by scanning electron microscopy (SEM), atomic force microscopy (AFM) and Raman scattering spectroscopy (RSS). The aim of this study was to verify the interface between bone and MD and ND, surgically implanted in the femoral diaphysis of Wistar rats, after 4 and 8 weeks. The outcome was evaluated by scanning electron and optical microscopy using a semi quantitative method. The results suggest that nanocrystalline diamonds (ND) elicits a richer biological response than microcrystalline diamonds (MD) when in interaction with bone.

Synthesis and Characterization of a Novel Biodegradable Material, Poly(Lactic Acid-co-Tryptophane)

With cheap D,L-lactic acid (D,L-LA) and tryptophan (Try) as starting materials, a novel biodegradable material, poly(lactic acid-co-tryptophane) (P(LA-co-Try)), was synthesized via melt co-polycondensation. When the molar feed ratio LA/Try is 90:10, the influences of different conditions, including catalyst kinds and its dosage, co-polymerization time and temperature on the synthesis of the polymer are discussed. When SnCl2/ZnO (weight ratio 7:3) was used as catalyst at a dose of 0.7 wt% of the pre-polymer, 8 h direct-melt polycondensation at 160°C and absolute pressure of 70 Pa after pre-polymerization gave the co-polymer with a maximum intrinsic viscosity [η] of 0.73 dl/g. The structure of the co-polymer was characterized by FT-IR and 1H-NMR. According to the optimal synthetic conditions, co-polymers with different molar feed ratios were synthesized and systematically characterized by [η], FT-IR, 1H-NMR, GPC, DSC and XRD. The GPC results show that the maximum weight-average molecular weight (M w) of P(LA-co-Try) is 6500 when the molar feed ratio LA/Try is 98:2. With the increase of the molar feed ratio of Try, [η], M w and its polydispersity index (M w /M n) decrease gradually. Due to the introduction of Try with a big aromatic ring into the co-polymer, the glass-transition temperature (T g) increases gradually with the increasing feed charge of Try and all co-polymers are amorphous. Direct-melt co-polycondensation is a cheap and practical method for the synthesis of Try-modified poly(lactic acid), a potential biomedical material, especially when used as a drug-delivery carrier.

Strong adhesion of Saos-2 cells to multi-walled carbon nanotubes

Abstract In recent years, carbon nanotubes (CNTs) have been considered potential biomedical materials because of their unique character. The aim of this study was to investigate the response of a human osteoblast-like cell line – Saos-2 – on single-walled CNTs (SWCNTs) and multi-walled CNTs (MWCNTs). The surface of a culture dish was coated with CNTs, and Saos-2 cells were cultured for three days. Cell morphology, viability, alkaline phosphatase (ALP) activity, adhesion, and vinculin expression were evaluated. The result showed high cell viability and strong adhesion to MWCNTs. Saos-2 cultured on MWCNTs exhibited vinculin expression throughout the cell body, while the cells attached to SWCNTs and glass were mostly limited to their periphery. Our results suggest that CNT coatings promote cell activity and adhesiveness. These findings indicate that MWCNTs could be used as surface coating materials to promote cell adhesion.

Synthesis and characterisation of styrene butadiene styrene-g-acrylic acid for potential use in biomedical applications

The work undertaken investigates the mechanical and thermal properties of styrene butadiene styrene (SBS) grafted with acrylic acid (AA) for use as a potential biomedical material. SBS-g-AA was synthesised by UV polymerisation and analytical techniques such as differential scanning calorimetry (DSC), attenuated total reflectance infrared Fourier transform spectrometry (ATR-FTIR), dynamic mechanical thermal analysis (DMTA) and tensile tests were used to characterise the grafted copolymers. From the DSC analysis, the glass transitions of polystyrene (PS) and polybutadiene (PB) domains present in the SBS copolymer were detected at 67 °C and − 90 °C respectively. ATR-FTIR spectral analysis was used in conjunction with the DSC thermographs to analyse the grafted copolymers. The peak (1711 cm − 1 ) associated with C O stretching in poly acrylic acid was located at 1725 cm − 1 on the grafted SBS-g-AA copolymer which confirmed grafting took place. Mechanical testing was carried out to analyse the physical attributes of the grafted copolymers. It was found that a decrease in Young's modulus and stress at break occurred for SBS-g-AA copolymers which were soxhlet extracted using chloroform (washed). It was evident from the DMTA results that the glass transition values for each of the washed grafted samples increased, thus establishing that grafting had occurred onto the various butadiene segments along the SBS backbone. The results showed that the hydrophilic monomer was successfully grafted onto a hydrophobic polymer and the mechanical and thermal properties were in the useful range for biomedical applications.

Microstructure–mechanical property relationships in ultrafine-grained NbZr

The present paper reports on the microstructure–mechanical property relationships in an ultrafine-grained (UFG) niobium–1 wt.% zirconium (NbZr) alloy, a potential biomedical material, severe plastically deformed at room temperature utilizing equal channel angular extrusion (ECAE). Monotonic tensile and low-cycle fatigue (LCF) experiments were carried out on the NbZr samples processed along ECAE routes 8B C and 16E, along with extensive microstructure analysis. The important finding is that the NbZr alloy processed along ECAE routes that lead to a higher volume fraction of high-angle grain boundaries (HAGBs) exhibits a stable cyclic deformation response in the LCF regime. This stands in good agreement with prior studies on other materials, such as UFG interstitial-free steel, in which the stable fatigue behavior was associated with the dominance of HAGBs. The current results provide a venue for utilizing the UFG NbZr alloy in biomedical applications that require a combination of long-term durability, high strength and very good biocompatibility, where the latter is not altered by ECAE processing. Furthermore, for the first time, we present guidelines for optimizing processing parameters that define the microstructure–cyclic stability relationship in UFG alloys.

Biocompatibility of Cerium Oxide Films Synthesized by Dual Plasma Deposition

Cerium oxide films have been fabricated using dual plasma deposition. X-ray diffraction. (XRD) reveals a crystalline phase and X-ray photoelectron spectroscopy (XPS) shows that La exists predominantly in the +4 oxidation state. The activated partial thromboplastin time is longer than that of blood plasma and stainless steel. Furthermore, the numbers of adhered, aggregated and morphologically changed platelets are reduced compared to low-temperature isotropic carbon (LTIC). HUVEC cells exhibit good adhesion and proliferation behavior on cerium oxide films. This study suggests rare earth oxide films are potential blood-contacting biomedical materials.

Hemocompatibility of lanthanum oxide films fabricated by dual plasma deposition

Lanthanum oxide films were fabricated using dual plasma deposition. X-ray photoelectron spectroscopy (XPS) showed that La existed in the + 3 oxidation state. X-ray diffraction (XRD) revealed a (101) oriented hexagonal structure. Blood platelet adhesion tests and endothelial cell cultures were used to evaluate the hemocompatibility of the as-deposited films. Scanning electron microscopy (SEM) and optical microscopy were employed to evaluate the surface morphology of the blood platelets and endothelial cells on the films. The results showed that the number of adhered, aggregated and morphologically changed platelets was reduced compared to that observed on low-temperature isotropic carbon (LTIC). Endothelial cells culture tests indicated good adhesion and proliferation of human umbilical vein endothelial (HUVE) cells in vitro. Our study suggests that lanthanum oxide films are potential blood-contacting biomedical materials.

Cellular interactions and degradation of aliphatic poly(ester amide)s derived from glycine and/or 4-amino butyric acid

A series of poly(ester amide)s derived from amino acid (glycine or 4-amino butyric acid), diol (1,6-hexanediol or 1,4-butanediol) and sebacoyl chloride were prepared by interfacial polymerization. FT-IR analysis indicated that for poly(ester amide)s derived from glycine, only amide–amide hydrogen bonds and hydrogen-bonded C=O ester groups were established, whereas the poly(ester amide)s derived from 4-amino butyric acid contained amide–amide hydrogen bonds and amide–ester hydrogen bonds, including NH groups and C=O ester groups in free state. The biodegradability was estimated by weight residue of poly(ester amide) films in pH 6 buffer solution with papain at 37°C. The poly(ester amide) films derived from glycine demonstrated significantly improved degradability compared to the poly(ester amide) films derived from 4-amino butyric acid. This difference of degradation rate could be explained by the bonding state in C=O ester groups. The cellular interaction of the poly(ester amide)s was studied by measuring the proliferation of human dermal fibroblasts on the polymer films. The cells proliferated significantly faster on poly(ester amide) films derived from 4-amino butyric acid than on poly(ester amide) films derived from glycine. These results suggest that the poly(ester amide) prepared in this study may serve as a potential cell-compatible biomedical material.

Characterization of hydrogels based on chitosan and copolymer of poly(dimethylsiloxane) and poly(vinyl alcohol)

AbstractCopolymers composed of poly(vinyl alcohol) (PVA) and poly(dimethylsiloxane) (PDMS) were crosslinked with chitosan to prepare semi‐interpenetrating polymer network (IPN) hydrogels by an ultraviolet (UV) irradiation method for application as potential biomedical materials. PVA/PDMS copolymer and chitosan was cast to prepare hydrogel films, followed by a subsequent crosslinking with 2,2‐dimethoxy‐2‐phenylacetophenone as a nontoxic photoinitiator by UV irradiation. Various semi‐interpenetrating polymer networks (semi‐IPNs) were prepared from different weight ratios of chitosan and the copolymer of PVA/PDMS. Photocrosslinked hydrogels exhibited an equilibrium water content (EWC) in the range of 65–95%. Swelling behaviors of these hydrogels were studied by immersion of the gels in various buffer solutions. Particularly, the PCN13 as the highest chitosan weight ratio in semi‐IPN hydrogels showed the highest EWC in time‐dependent and pH‐dependent swelling. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 84: 2591–2596, 2002

Physical and mechanical behavior of electron-beam irradiated and ethylene oxide sterilized multiblock polyester.

The effect of two sterilization treatments (electron-beam radiation and ethylene oxide gas) on the structure and mechanical properties of a multiblock copolymer were investigated to establish the effects of the sterilizing procedures on potential biomedical material. The material was exposed for different radiation doses in order to find an optimum dose of electron-beam radiation. Characterization techniques employed include gel permeation chromatography, infrared spectroscopy, differential scanning calorimetry, dynamic mechanical thermal analysis and tensile testing. The optimal dose of radiation at which no change in structure and mechanical properties occurred was found as 25 kGy. Ethylene oxide gas treatment also did not affect the structure and properties of the polymer and it can be recommended as an alternative sterilization route for the studied polymer.

Synthesis and properties of poly(ethylene glycol) macromer/beta-chitosan hydrogels.

Semi-interpenetrating polymer network (semi-IPN) hydrogels composed of beta-chitosan and poly(ethylene glycol) diacrylate macromer (PEGM) were synthesized and characterized for the application as potential biomedical materials. The mixture of PEGM and beta-chitosan, dissolved in water including a small amount of acetic acid, was cast to prepare hydrogel films, followed by a subsequent crosslinking with 2,2-dimethoxy-2-phenylacetophenone as a non-toxic photoinitiator by ultraviolet irradiation. Photocrosslinked hydrogels exhibited relatively high equilibrium water content in the range 77-83% which is mainly attributed to the free water content rather than to the bound water, hydrogen bonded with components in semi-IPN hydrogels. The crystallinity, thermal properties and mechanical properties of semi-IPN hydrogels were studied. All the photocrosslinked hydrogels revealed a remarkable decrease in crystallinity. The glass transition temperatures, Tg, of crosslinked PEGM segment in semi-IPNs increased compared with poly(ethylene glycol) itself. However, with increasing beta-chitosan content their Tg decreased owing to the higher degree of crosslinking. The tensile strengths of semi-IPNs in dry state were rather high, but those of hydrogels in wet state decreased drastically.