STERIC STABILIZATION OF NANOPARTICLES - SIZE AND SURFACE-PROPERTIES

Nanoparticles of poly-(isobutylcyanoacrylate) (PIBCA), poly-lactic aci d (PLA), poly-lactic-co-glycolic copolymer (PLAGA) and poly-epsilon-ca prolactone were prepared according to conventional methods. In the pre paration of PIBCA nanoparticles different steric stabilizers were used . Formulations included poloxamer 188, polyvinilic alcohol (PVA) or po lyethyleneglycol 2000 (PEG 2000), with or without dextran, in order to characterize the influence of different steric stabilizers. All the f ormulations were tested for their electrophoretic mobility, zeta poten tial and particle size using DELSA. Particle size measurements were al so performed using a PCS technique, employing two sets of apparatus, i n an attempt to evaluate the influence of measuring principle and dete ction angle in the final results. Results indicate that PIBCA nanopart icles can be sterically stabilized by dextran, poloxamer and PVA, but PEG 2000 could need the presence of another steric stabilizer. The goo d correlation for the same detection angle between PCS and DELSA demon strates the importance of DELSA in the characterization of size and su rface properties associated with colloidal drug carriers like nanopart icles, as demonstrated by PLA, PLAGA and PCL nanoparticles (monodisper se particles). The differences between the two techniques could be exp lained by different detection angles and strongly suggests an integrat ed approach using PCS and DELSA when considering polydisperse particle populations.