Degradation and Stability of PBCA and POCA Nanoparticles
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- Institutt for fysikk 
Nanoparticles represent promising carriers for controlled drug delivery. In this project threedifferent intruments: Zetasizer, Nanosight and Gas Chromatography, have been used to detect and analyse degradation of monodisperse poly butylcyanoacrylate (PBCA) and polyoctylcyanoacrylate (POCA) nanoparticles with a mean size diameter of 145 and 155 nm,respectively. It was found that the Nanosight and Gas Chromatography are valuable instrumentsfor detecting and analysing degradation, whereas the Zetasizer turned out to giveunreliable results because of increasing polydispersity in the samples. PBCA and POCAparticles were tested in two different setups. One including a dialysis setup in room temperature,in which the solvent was regularly exchanged. The other consisted of reagent bottlesheld in an oven at 37C. In the dialysis method the influence of buffers with pH 4.0, pH5.5 and pH 7.4 were tested. In the reagent bottles different mediums were tested, like cellmedium, blood serum and buffer pH 7.4 with and without the enzyme esterase. From theseexperiments it became clear that PBCA particles degraded significantly faster than POCAparticles in all tested mediums. Degradation of PBCA particles were also strongly affectedby the pH. At pH 4.0 there was little (10%) or no degradation still after 30 days. The concentration of PBCA particles in pH 7.4 decayed as a 1/x -function, in which 53\% of the PBCA particles in buffer pH 7.4 have been degraded after 8.5 hours.The degradation-rate for PBCA and POCA in blood serum was approximately similar as in buffer pH 7.4, whereas in cell medium it was slightly slower.