An implant system that undergoes a gradual, time-dependent, nontoxic degradation process may offer an efficacious, safe, and desirable alternative to metallic materials used in the treatment of various musculoskeletal conditions. Such a scaffold may also be a suitable vehicle for growing cells and tissue in the laboratory for tissue engineering applications. We have used a scaffold of this type previously in animal studies for biological resurfacing of large articular cartilage defects.(1) This study examined important in vitro degradation characteristics of a 50:50 polylactic acid/polyglycolic acid (PLG) implant during an 8-week period. It was determined that this particular implant degraded in a biphasic fashion. The initial phase occurred during the first 2 weeks with a decrease in molecular weight and surface axial strain, coupled with an increase in percent porosity. The second phase demonstrated a decline in surface axial strain by 4 weeks and an ongoing decline in molecular weight. Loss of gross structural properties was not evident until the start of the second phase and was complete at 8 weeks. This study demonstrated the potential uses for this implant as a means of providing structural support for cells and tissue ingrowth for up to 8 weeks. Further studies need to be conducted in order to determine the biological effects of the degrading polymer byproducts on host tissues.

No abstract

The Briggs-Rauscher (BR) reaction is free radical based where the kinetics of formation of different iodide species leads to potentiometric and color oscillations. These oscillations were monitored in this study using a UV/Vis attenuated total reflection probe to develop an assay to measure the antioxidant content in complex matrices. The periodicity of the BR reaction was found to be very consistent (range 24–25 seconds, n = 16). Adding various amounts of ascorbic acid, a well-known antioxidant, led to an inhibition of the reaction with a linear calibration curve of antioxidant periodicity time (APT, r 2 > 0.99). The validity of this test in complex matrices was studied by determining the APT of nine fruits, and the resulting antioxidant capacity in ascorbic acid equivalency was calculated. The results generated by this assay were found be accurate through comparison with the well-established FRAP assay. These results show that visual or spectrometric monitoring of BR reaction can be used as a reliable, quick, and inexpensive alternative to more established assays with the added advantage that values generated from this assay is at pH 2 which is similar to that in the human stomach.