Interaction of CO2 laser-modified nylon with osteoblast cells in relation to wettability

Applied Surface Science

2011

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1522 668891 -AbstractWith an ageing population the demand for cheap, efficient implants is ever increasing. Laser surface treatment offers a unique means of varying biomimetic properties to determine generic parameters to predict cell responses. This paper details how a KrF excimer laser can be employed for both laser-induced patterning and whole area irradiative processing to modulate the wettability characteristics and osteoblast cell response following 24 hour and 4 day incubation. Through white light interferometry (WLI) it was found that the surface roughness had considerably increased by up to 1.5 µm for the laser-induced patterned samples and remained somewhat constant at around 0.1 µm for the whole area irradiative processed samples. A sessile drop device determined that the wettability characteristics differed between the surface treatments. For the patterned samples the contact angle, θ, increased by up to 25° which can be attributed to a mixed-state wetting regime.For the whole area irradiative processed samples θ decreased owed to an increase in polar component, γ P . For all samples θ was a decreasing function of the surface energy. The laser whole area irradiative processed samples gave rise to a distinct correlative trend between the cell response, θ and γ P . However, no strong relationship was determined for the laser-induced patterned samples due to the mixed-state wetting regime. As a result, owed to the relationships and evidence of cell differentiation one can deduce that laser whole area irradiative processing is an attractive technology for employment within regenerative medicine to meet the demands of an ageing population.Keywords: Excimer laser, nylon 6,6, wettability, osteoblast cells, bioactivity, regenerative medicine. -IntroductionIt has been realized worldwide within the scientific community and various industries that lasers offer major advantages over alternative techniques for materials processing [1][2][3][4]. Some of the main advantages of using a laser for materials processing are:• Relative cleanliness.• Accurate processing.o Allows much control over the Heat Affected Zone (HAZ) due to the ability of relative precise control over the thermal profile and thermal penetration/absorption.• Precise placement of the beam onto the target material allowing user specified areas of the target material to be processed.• Post-processing techniques required are usually minimal.• Non-contact processing.• Automation (repeatability) of the various processing techniques using a laser is relatively easy to implement.With a large number of different lasers now commercially available it is possible for one to deduce that almost all materials can be processed using a laser due to the wide range of laser parameters that can be utilized. With the many benefits of using lasers for materials processing it has been found that the interest in laser-induced surface treatment has grown, especially within the biomedical industry. This is due to the fact that lasers offer the user a highly selective, rapid...

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confidence: 99%

Wettability and osteoblast cell response modulation through UV laser processing of nylon 6,6

Applied Surface Science

2011

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“…But, Table 1 shows that this is not the case for the CO 2 laser-induced patterned samples as θ had increased by up to 10° even though a maximum increase in Sa was determined to be around 0.5 µm when compared to the asreceived sample (AR). As hypothesized previously [29,30], this phenomenon can be explained by the existence of a mixed-state wetting regime [31][32][33][34]. That is, the liquid, when in contact with the sample surface, gave rise to a mixture of Wenzel and Cassie-Baxter regimes.…”

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confidence: 55%

“…Through previous work it has already been identified that the CO 2 laser-material interaction is that of a thermolytical nature, giving rise to melting and re-solidification [29,30]. As a result of this interaction, CO 2 laser-induced patterning of the nylon 6,6 surfaces gave rise to a significant variation in topography when compared to the as-received sample (AR).…”

Section: -Co 2 Laser-induced Patterningmentioning

confidence: 99%

Osteoblast cell response to a CO2 laser modified polymeric material

Optics and Lasers in Engineering

Brown

2012

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-AbstractLasers are an efficient technology which can be applied for the surface treatment of polymeric biomaterials to enhance insufficient surface properties. That is, the surface chemistry and topography of biomaterials can be modulated to increase the biofunctionality of that material. By employing CO 2 laser patterning and whole area processing of nylon 6,6 this paper details how the surface properties were significantly modified. Samples which had undergone whole area processing followed current theory in that the advancing contact angle, θ, with water decreased and the polar component, γ p , increased upon an increase in surface roughness. For the patterned samples it was observed that θ increased and γ P decreased. This did not follow current theory and can be explained by a mixed-state wetting regime. By seeding osteoblast cells onto the samples for 24 hours and 4 days the laser surface treatment gave rise to modulated cell response. For the laser whole area processing, θ and γ P correlated with the observed cell count and cover density. Owed to the wetting regime, the patterned samples did not give rise to any correlative trend. As a result, CO 2 laser whole area processing is more likely to allow one to predict biofunctionality prior to cell seeding. What is more, for all samples, cell differentiation was evidenced. On account of this and the modulation in cell response, it has been shown that laser surface treatment lends itself to changing the biofunctional properties of nylon 6,6.Keywords: Laser surface treatment, osteoblast cells, wettability, nylon 6,6, bioactivity. -IntroductionOn account of the population living longer and biotechnology having the potential to improve quality of life there is an ever increasing interest in this field [1][2][3][4][5][6]. More times than not there usually has to be a compromise between bulk and surface properties when determining the best polymeric materials to use [7,8]. In most cases the bulk properties are seen more in favour over those surface properties required [8]. As a result of this, surface properties are not sufficient in terms of the level of bioactivity required giving rise to clinical failure of the implant [9]. Leading on from this, there is a necessity of developing a technique to change the surface properties to enhance and predict the cell response.Through prior research other methods such as plasmas [10][11][12][13], photochemical techniques [14][15][16] and coating technologies [3,[17][18][19] offer the ability to vary the physiochemical properties of the polymer surface without changing the bulk properties. These various techniques have the ability to improve cell growth and adhesion on polymeric biomaterials; however controlled, precise modification is lacking from the methods named. Laser surface treatment offers the ability to vary the physiochemical surface properties simultaneously with considerably more control and accuracy in comparison to the other possible techniques [20,21]. Furthermore, lasers offer a convenient means of modifying ...

“…Furthermore, it has been evidenced that there is a relationship between the wettability characteristics and bioactive nature of the nylon® 6,6 in terms of osteoblast cell growth [8].…”

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confidence: 99%

“…As a result of this, in order to achieve the best possible results from a polymeric biomaterial a range of skills are required that span over multiple disciplines. As such, throughout the research of many over this multi-disciplinary subject it has been realized that both the bulk and surface properties of all biomaterials hold the ability to influence the degree of bioactivity [8,[12][13][14].…”

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confidence: 99%

Modulating calcium phosphate formation using CO2 laser engineering of a polymeric material

Materials Science and Engineering: C

2012

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The use of simulated body fluid (SBF) is widely used as a screening technique to assess the ability of materials to promote calcium phosphate formation. This paper details the use of CO 2 laser surface treatment of nylon® 6,6 to modulate calcium phosphate formation following immersion in SBF for 14 days. Through white light interferometry (WLI) it was determined that the laser surface processing gave rise to maximum Ra and Sa parameters of 1.3 and 4.4 µm, respectively. The use of X-ray photoelectron spectroscopy (XPS) enabled a maximum increase in surface oxygen content of 5.6 %at. to be identified. The laser-induced surface modifications gave rise to a