The aim of this proposal is to examine the feasibility of a new characterization technology (i.e., Laser Confocal Microscopy) to study a common problem associated with biodegradable surgical implants, particularly those used in orthopaedic surgery. The accumulation of acidic degradation products during biodegradation is widely believed to result in an increase in local acidity in the interior of a bulk biodegradable surgical implant. This higher local acidity in the interior of a biodegradable device during hydrolytic degradation would accelerate the. hydrolysis through acid autocatalysis and hence accelerate the loss of the mechanical properties of the implant. However, there are no experimental data to support this widely accepted belief up to the present. Our objective of this proposal is to develop new laser confocal microscopic techniques so that the required experimental data could be obtained to either support or disapprove this belief. An experimental proof of this widely held belief would provide a scientific basis for future design of new and improved biodegradable materials for surgical use. Specifically, PI plans to prepare several biodegradable substrates with different size and shape through injection molding process. Both cylindric and rectangular shaped specimens will be made and their diameter (cylinder) or thickness (rectangular) will vary from 0.5 to 2.0 mm. These simpler geometry allow PI to study the problem with fewer parameters. This approach is important when the goal is to develop a new technique for materials characterization. The biodegradable specimens prepared above will be subject to in vitro hydrolysis for predetermined periods. A new laser confocal microscopic (LCM) technique will be developed to quantitatively examine the pH values of the partially hydrolyzed biodegradable specimens as a function of depth from the surface of the specimens. The pH profiles as a function of depth of the specimens would be established. These data would allow us to either support or disapprove the widely speculated belief described above.
| Slivka, M A; Chu, C C (1997) Fiber-matrix interface studies on bioabsorbable composite materials for internal fixation of bone fractures. II. A new method using laser scanning confocal microscopy. J Biomed Mater Res 37:353-62 |
| Slivka, M A; Chu, C C; Adisaputro, I A (1997) Fiber-matrix interface studies on bioabsorbable composite materials for internal fixation of bone fractures. I. Raw material evaluation and measurement of fiber-matrix interfacial adhesion. J Biomed Mater Res 36:469-77 |
