Figure 3.

(a) Poisson distribution of dendrimer-methotrexate conjugates G5-MTX_n 2a–2d, each having the MTX mean of 1.1, 2.6, 5.0, or 7.1, respectively. (b) A plot of fractional desorption of G5-MTX_n 2a – 2d as a function of mean MTX number (valency). The fractional desorption was calculated from the SPR binding studies of the dendrimer conjugates. The sum of the fractions ( ${\displaystyle \sum _{n=0}^i}{Fr}_n$) for multivalent species (G5-MTX_n; n = 0 to 18) distributed in each of the dendrimer MTX conjugates is also plotted separately in the secondary y-axis. The value for Fr is defined as the fraction of n-valent species relative to all the species that comprise each conjugate. As an illustration, each value for ${\displaystyle \sum _{n=1}^i}{Fr}_n$ (where i = 2) in 2a–2d refers to the sum of the two fractions for a monovalent (Fr ₁) and divalent (Fr ₂) species, each calculated by Poisson distribution of the conjugates above.