Fig. 4.
In vivo bioluminescence signal intensities for microspheres of varying molecular weight PLG. Two populations of microspheres with the same DNA loading (approximately, 5 μg of DNA/mg of microspheres) were fabricated with high (◆) and low (●) molecular weight PLG. Signal levels for (●) are those shown in Fig. 2 through 35 days, and are replotted for convenient comparison. Control conditions included microspheres without pLuc (x) and background light emission (○).