Estimation of tissue-partition coefficients and clearance for liposomic nanoparticles
Regarding the tissue partition coefficient, Li et al. said:  "By using such a parameter, it is assumed that there is the same transfer kinetics of nanoparticles from blood into tissues as from tissues back into blood circulation, and an equilibrium of concentrations between blood and tissue exists. These assumptions may not be appropriate for nanoparticles."


Physiologically Based Pharmacokinetic Modeling of Nanoparticles
Mingguang Li, Khuloud T. Al-Jamal, Kostas Kostarelos, and Joshua Reineke
ACS Nano 2010 4 (11), 6303-6317
DOI: 10.1021/nn1018818 


However if you are set on using a tissue:blood partition coefficient (Kp), Yun and Edginton have done a review of 6 in silico methods for determining Kp for small molecules.  You may be able to extrapolate to nanoparticles.


Yun, Y.E., Cotton, C.A. &amp; Edginton, A.N. J Pharmacokinet Pharmacodyn (2014) 41: 1. doi:10.1007/s10928-013-9342-0


Finally, if you are looking for data to help determine a partition coefficient, there is an excellent review of liposomal doxorubicin pharmacokinetic data in animals and humans here.


Gabizon, A., Shmeeda, H. &amp; Barenholz, Y. Clin Pharmacokinet (2003) 42: 419. doi:10.2165/00003088-200342050-00002