Enhanced Tumour Uptake of Doxorubicin Loaded Poly(butyl cyanoacrylate) Nanoparticles in Mice Bearing Dalton's Lymphoma Tumour

The objective of this study is to enhance the delivery of Doxorubicin hydrochloride to Dalton's lymphoma solid tumour through poly(butyl cyanoacrylate) (PBC) nanoparticles. Doxorubicin loaded PBC (DPBC) nanoparticles were prepared by emulsion polymerization and characterized by particle size analysis, zeta potential and scanning electron microscopy. Doxorubicin HCl (Dox) and DPBC nanoparticles were radiolabeled with ^99mTc by reduction method using stannous chloride and optimized the labeling parameters to obtain high labeling efficiency. The in vitro stability of ^99mTc-labeled complexes was determined by DTPA and cysteine challenge test. The labeled complexes showed very low transchelation and high in vitro and serum stability. ^99mTc labeled complexes of Dox and DPBC nanoparticles were administered subcutaneously below the Dalton's lymphoma tumour and biodistribution was studied. The distribution of DPBC nanoparticles to the blood, heart and organs of RES such as liver, lung and spleen was biphasic with a rapid initial distribution, followed by a significant decrease later at 6 h post-injection. The distribution of Dox to tissues was very low initially and increased significantly at 6 h post-injection indicating its accumulation at the injection site for a longer time. The concentration of DPBC nanoparticles was also found high in tissues at 6 h post-injection indicating their accumulation at the subcutaneous site and consequent disposition to tissues with time. A significantly high tumour uptake of DPBC nanoparticles (～13 fold higher at 48 h post-injection) (P <0.001) was found compared to free Dox. The tumour concentrations of both Dox and DPBC nanoparticles increased with time indicating their slow penetration from the injection site into tumour. The concentration of DPBC nanoparticles in the femur bone in the tumour region was also significantly higher (P <0.001) than free Dox and increased with time. The study signifies the advantage of delivering Dox to Dalton's lymphoma through PBC nanoparticles by facilitating enhanced tumour uptake and prolonged tumour retention, which are expected to lead to greater therapeutic effect in the form of tumour regression.