BSA aggregation

Figure 2 Effect of Mg(OH)2 content on BSA release kinetics (A) and encapsulated BSA aggregation kinetics (B) during incubation of the PLGA implants at 37°C in PBST. Millicylinders were loaded with 15% BSA and 0% ( ), 0.5% (H), and 3.0% (A) Mg(OH)2 (average S.E., n = 3). (From Ref. 8.)...

Table 3 Effect of Mg(OH)2 and BSA Content on BSA Aggregation in BSA/PLGA (0.63 dl/g) Millicylinders after 4-Week Release Study in PBST at 37° C...

In the anhydrous microencapsulation, protein and excipients were suspended/dissolved in PLA/acetonitrile solution and then added to cottonseed oil to form an o/o emulsion with Span 85 as an emulsifier. Petroleum ether was then added to extract the acetonitrile and the microspheres were hardened. The microspheres were then recovered by filtration and dried under vacuum. As shown in Table 5 and Fig. 5, without the pore-forming PEG, only 36% BSA was released from PLA microspheres in 1-month of incubation with a total recovery (released-fall soluble and aggregated residue in polymer after release) of 76%. Blending in 30% of 35 kDa PEG with the PLA eliminated the BSA aggregation in polymer completely, with 82% of encapsulated BSA released in 1 month. The improved BSA stability in PLA/PEG microspheres could be attributed to a less acidic and more hydrophilic microenvironment in the polymer. As seen in Fig. 6, unlike PLGA 50/50, which caused a dramatic pH drop in the release medium after a 4-week incubation (41), a relatively neutral pH was retained in the release medium for both PLA and PLA/PEG microspheres. A slightly lower pH in the release medium incubated with PLA/PEG microspheres relative to that in PLA was also... 

Effect of PEG on BSA Aggregation in 0/0 Microspheres after 29-day Release Study in PBST at... 

Table 7 Effect of Encapsulation Method, Histidine, and Trehalose on f-BSA Aggregation in Microspheres after Exposure to 80% R.H. and 37° C...

FIGURE 14.1 The SMSLS for determining kinetics of protein (BSA) aggregation at various temperatures, measured in terms of the ratio of Mjit) of the aggregates to the initial unaggregated mass M. The kinetics vary so markedly over the range studied that the time axis is shown on a log scale. 

Solutions of BSA aggregates with the middle size 100 nm were obtained by heating 5 g of 5 wt % solution of the native BSA sample at 57°C for 10 min and subsequent dilution to the desired concentrations. 

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