Table II.
Calculated N:P ratios over time
| Day | siRNA1-PEI-loaded PLGA MPs | siRNA2-PEI-loaded PLGA MPs |
|---|---|---|
| 0.1 | 2 ± 0a,b | 3 ± 1 |
| 0.2 | 3 ± 1 | 3 ± 1 |
| 0.3 | 3 ± 1 | 5 ± 3 |
| 0.5 | 3 ± 1 | 3 ± 1 |
| 1 | 1 ± 0 | 3 ± 1 |
| 2 | 0 ± 0 | 1 ± 1 |
| 3 | 7 ± 1 | 9 ± 2 |
| 4 | 14 ± 2 | 5 ± 1 |
| 8 | 38 ± 8 | 34 ± 7 |
| 11 | 2 ± 1 | 4 ± 1 |
| 14 | 0 ± 0 | 2 ± 1 |
| 17 | 0 ± 0 | 1 ± 0 |
| 21 | 1 ± 0 | 1 ± 1 |
| 25 | 0 ± 0 | 1 ± 1 |
| 28 | 0 ± 0 | 0 ± 0 |
N:P ratios expressed with P set to 1. For instance, an N:P of 2:1 is expressed as “2.”
Calculated from the actual amount of siRNA and PEI detected from (n = 4) PLGA MP release samples for each group at each timepoint, as previously described [8]. To calculate the moles of phosphate (P) for the N:P ratio, the amount of siRNA was divided by its molecular weight (provided by the manufacturer) and then multiplied by 42 (since the siRNA used was double-stranded and 21 base pairs in length, yielding 42 phosphates per siRNA molecule). The moles of nitrogen (N) for the N:P ratio were approximated by dividing the amount of PEI by the molecular weight of the monomer (C2H5N) of linear PEI and then multiplying by 1 (since there is 1 mol of N per mol of monomer). The resulting N:P ratio is expressed as mean ± standard deviation for (n =4) siRNA and PEI measurements.