Characterization of the interaction between protein loaded polymeric nanoparticles and supported lipid bilayers towards improved drug delivery systems

Examensarbete för masterexamen
Master Thesis
De Battice, Laura
The development of nanoparticles (NPs) for the delivery of therapeutic agents has introduced new opportunities for the improvement of medical treatment. Among these opportunities, surface based analytical techniques are promising tools to improve our understanding of biointerfacial phenomena, such as NP interactions at biological barriers. The University of Liège (ULg), Belgium, has recently developed electrostatically assembled NPs, made of polycationic polymers and biopharmaceutical drugs with the intention of promoting their delivery through non-invasive administration. Adopting polymers of four different number average molecular weight (Mn) and procedures of the ULg, we successfully reproduced the preparation of those NPs either loaded with Human Insulin (HI) or chicken Ovalbumin (OVA). The formulation of this latter protein has highlighted interesting findings related to problems in its solubilization. An unexpected aggregation of this protein has been directly correlated to the agitation mode adopted and was found to be time and pH dependent. NPs, prepared at Chalmers or provided by the ULg, were characterised by Dynamic Light Scattering (DLS) and Nanoparticle Tracking Analysis (NTA). Typically, NP size was about 200 nm in diameter with a relatively good agreement between these two techniques. In addition, the analysis of their electrophoretic mobility (zeta potential measurement) showed that these NPs were positively charged with a zeta potential of around +25 mV. Difficulties were encountered with respect to the OVA dissolution state, and high-quality OVA loaded NPs could not be formed. This interesting aggregation phenomenon, that could not be totally suppressed, was found to depend on pH, on filtering, and on time of dissolution. Using the Quartz Crystal Microbalance with Dissipation monitoring technique (QCM-D), we studied in real time the interaction between HI loaded NPs and both neutral and negatively charged model lipid membranes, successfully formed on SiO2 coated crystals. First, the four polycationic polymers of different Mn were investigated. We found that the electrostatic properties of the polymers had a determinant role in their interaction with the model lipid membranes: on a negatively charged model lipid membrane, the polycations irrespectively of their Mn collapsed and formed thin and rigid layers, whereas hydrated viscoelastic layers, as indicated by a high dissipation by QCM-D, were formed on a neutral membrane. A different behaviour was observed for the NPs. We found that, on a negatively charged membrane, NPs formed increasingly dissipative layers for higher Mn of the polycation used to prepare the NPs. Thicker layers were formed on a neutral membrane. Functionalized NPs with a ternary compound were also investigated. Interestingly, without modifying drastically the mean size or the Zeta potential of the NP, the presence of this additional compound was shown to alter completely the adsorption profile and total amount of NP on the negatively charged membrane, with appearance of a transient mass uptake. The difference in interaction profiles between binary and ternary NPs makes the study of those NPs very interesting in terms of drug release.
Nanovetenskap och nanoteknik , Fysik , Biologiska vetenskaper , Nanoscience & Nanotechnology , Physical Sciences , Biological Sciences
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