Laser surface treatment of polymeric biomaterials for enhanced cell response

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Biotechnology has the potential to improve people's quality of life and, despite public concerns, it holds the key to a number of unmet clinical needs. Biotechnology may be the next big thing after information technology. The UK biotechnology market is today worth 4.5 billion. Estimates of future growth in the market over the next five years range from 10 to 15%. Many see this growth being driven by the increased use of inexpensive and easy to manufacture polymeric biomaterials. Many different types of polymeric biomaterials are used in medicine as implants. Their applications range from facial prostheses to tracheal tubes, from kidney and liver parts to heart components, and from dentures to hip and knee joints. This wide variety of applications is because they can be easily fabricated into many forms: fibres; textiles; films and solids. Polymeric materials may also bear a close resemblance to natural tissue components, which allows for direct bonding with other substances.Although polymer science is a rapidly developing area of research, it remains that one of the most intractable problems encountered in bio and implant technology is that the performance of a polymeric biomaterial depends on the bulk and surface properties. More often than not these are in contrast to one another as the suitability of the surface properties is compromised in favour of the bulk properties. Compounding this trade-off is the fact that for certain applications and in certain instances the surface properties of the polymeric biomaterial are simply not suited to support sufficiently the level of bioactivity required. Typically, a polymeric biomaterial implant device will often fail clinically due to a lack of direct bonding with bone; that is, insufficient biointegration (osseointegration). This means that unless the surface of the polymeric biomaterial can be altered to become biomimetic (producing a surface that can mimic a natural biological surface) and provide the necessary level of bioactivity required without having a deleterious effect on the surface's performance, then either a generally more expensive solution has to be found or the implant idea will have to shelved - often the cost of the more expensive solution is too prohibitive and the implant idea is shelved. According to Dr. Matts Andersson, R&D Manager for Nobel Biocare Inc. (a 'sounding board' for clinical applications): No more can be done to improve a biomaterial's performance by working from the surface into the bulk; it is now time to concentrate on the surface to body to start to specify materials that signal to cells. Without an effective means of altering the surface properties of polymeric biomaterials the future uses of polymeric biomaterials in implant technology will likely remain as they are today.The options currently available to scientists working in the biotechnology field for altering the surface characteristics of polymeric biomaterials for increased biocompatibility are very limited. This places a limit on the extent to which the biotechnology market can expand because the lack of an effective means to treat the surface of polymeric biomaterials places a ceiling on the number of areas into which the materials can be applied. To improve biocompatibility, existing techniques typically only change one aspect of the surface characteristics, such as roughness. Lasers on the other hand change many aspects simultaneously - one such aspect is wettability. Wettability plays a significant role in promoting cell adhesion and growth. Previous work conducted with metals and ceramics revealed that there was a relationship between wettability and biocompatibility (the surface had enhanced properties and was more active). This project will focus on investigating and developing techniques to alter the surface chemistry and topography of selected polymeric biomaterials using IR and UV lasers to generate a more biocompatible surface (possessing enhanced surface propert