Design of Albumin‐Coated Microbubbles Loaded With Polylactide Nanoparticles. (1st August 2015) - Gauthier, Marianne
Abstract : Objectives: A protocol was designed to produce albumin‐coated microbubbles (MBs) loaded with functionalized polylactide (PLA) nanoparticles (NPs) for future drug delivery studies. Methods: Microbubbles resulted from the sonication of 5% bovine serum albumin and 15% dextrose solution. Functionalized NPs were produced by mixing fluorescent PLA and PLA‐polyethylene glycol‐carboxylate conjugates. Nanoparticle‐loaded MBs resulted from the covalent conjugation of functionalized NPs and MBs. Three NP/MB volume ratios (1/1, 1/10, and 1/100) and unloaded MBs were produced and compared. Statistical evaluations were based on quantitative analysis of 3 parameters at 4 time points (1, 4, 5, and 6 days post MB fabrication): MB diameter using a circle detection routine based on the Hough transform, MB number density using a hemocytometer, and NP‐loading yield based on MB counts from fluorescence and light microscopic images. Loading capacity of the albumin‐coated MBs was evaluated by fluorescence. Results: Loaded MB sizes were stable over 6 days after production and were not significantly different from that of time‐matched unloaded MBs. Number density evaluation showed that only 1/1 NP/MB volume ratio and unloaded MB number densities were stable over time, and that the 1/1 MB number density evaluated at each time point was not significantly different from that of unloaded MBs. The 1/10 and 1/100 NP/MB volume ratios had unstable number densities that were significantly different from that of unloaded MBs ( P < .05). Fluorescence evaluation suggested that 1/1 MBs had a higher NP‐loading yield than 1/10 and 1/100 MBs. Quantitative loading evaluation suggested that the 1/1 MBs had a loading capacity of 3700 NPs/MB. Conclusions: A protocol was developed to load albumin MBs with functionalized PLA NPs for further drug delivery studies. The 1/1 NP/MB volume ratio appeared to be the most efficient to produce stable loaded MBs with a loading capacity of 3700 NPs/MB.