Cellulose dialysis sacks

Pt dendrimer-encapsulated nanoparticles (PtDEN) were prepared via literature method12 (link). Firstly, a dendrimer stock solution (250 μM) was prepared by adding calculated amount of water to the G6-OH methanol solution. An aqueous solution of K₂PtCl₄ (10 mM, 5 mL) was then mixed with the dendrimer stock solution in a round-bottomed flask to obtain the desired Pt: G6-OH molar ratio of 40:1. The flask was purged with N₂ for 30 min, sealed tightly with a septum and stirred at room temperature for 66 h to achieve complete complexation of Pt²⁺ with the tertiary amines within the dendrimer interior. These precursor complexes were then reduced using a 20-fold molar excess of NaBH₄ from a freshly prepared aqueous solution (0.5 M) and the reduction was allowed to proceed for 8 h. Afterwards the reaction solution was purified by dialysis against 2 L of water in cellulose dialysis sacks with a molecular weight cutoff of 12000 (Sigma-Aldrich). The dialysis process occurred over 48 h with the water changed 4 times.

Cellulose dialysis sacks with a molecular weight cut-off pore size of 12 kDa (Sigma Aldrich, D6191-25EA, St. Louis, MO, USA) were used to monitor drug release profiles over 80 h. Dialysis sacks were soaked in PBS buffer overnight, 1.5 mL of sample was loaded into the cellulose tubing and placed in a beaker containing 20 mL of PBS and a small magnetic fly. The buffer was mixed continually throughout the experiment by stirring at 300 rpm. For the first 2 h of dialysis, 1 mL samples were taken at 30 min intervals, for the remainder of the first 48 h samples were taken every 60 min. Following each sampling, 1 mL of fresh PBS was reintroduced to maintain a total volume of 20 mL. Samples were diluted in ACN to dissociate polymer micelles and frozen until analysis.