Design and development of new bio-gated nanodevices for targeted controlled drug release

Abstract

The present PhD thesis, entitled Design and development of new bio-gated nanodevices for targeted controlled drug is focused on the design, synthesis, characterization and in vitro evaluation of new hybrid organic-inorganic nanosystems as innovative strategies for the targeted and controlled delivery of therapeutic molecules. The first chapter of this work is a general introduction that defines the context in which the projects carried out during this thesis are placed. In particular, the concept of nanomedicine is described, as well as the main strategies for the development of efficient nanopharmaceutical devices and the related challenges. Furthermore, a brief presentation of mesoporous silica materials is given. Next, the general objectives that are addressed in the following experimental chapters are introduced. The third chapter is focused on the development of a targeting delivery system directed to Toll-like receptor 3 (TLR3) and based on mesoporous silica nanoparticles capped with the synthetic double stranded RNA (dsRNA) polyinosinic-polycytidylic acid (poly(I:C)). Poly(I:C) has shown cytotoxic effects in different types of cancer, and the results obtained in this work demonstrate its ability to trigger apoptotic pathways in breast cancer cells, thanks to its interaction with TLR3. Furthermore, loading the mesopores with the anthracyclinic antibiotic doxorubicin, a commonly used chemotherapeutic agent, allowed to achieve an enhanced therapeutic effect. In fact, a higher decrease of the cellular viability in SK-BR-3 cell line was observed. Chapter four shows the design of a nanoparticles cooperation strategy. The aim of this work is to improve the efficacy of the previously developed therapeutic approach for breast cancer through the combination of two gated mesoporous silica nanoparticles sets able to cooperate to achieve a medical goal. The first type, in fact, induces changes that enhance the interaction of the second one with the target cancer cell. In order to do that, nanoparticles loaded with 9-cis-retinoic acid and capped with interferon-?, and nanoparticles loaded with sulforhodamine B dye and gated with poly(I:C) were synthesized. Taking advantage of the ability of both interferon-? and 9-cis-retinoic to increase TLR3 expression, we intended to improve the interaction of poly(I:C) functionalized nanoparticles with target cells. The obtained results show that the proposed combination strategy actually increased the uptake levels of poly(I:C) gated nanodevices in the cellular model selected. In the fifth chapter a system based on dendrimer-like mesoporous silica nanoparticles is presented. The higher pore volume of such materials makes them suitable for the achievement of the main aim of this project: the topical administration and controlled delivery of anti-vascular endothelial growth factor (VEGF) small interfering-RNA (siRNA) molecules to retinal pigmented epithelial cells. The nanodevices were synthesized, loaded with siRNA and finally functionalized with polyethylenimine chains, that act as molecular gate for the controlled release of the siRNA molecules and endosomal escape agent for cytosolic delivery. The obtained results in VEGF silencing in ARPE-19 cells highlight the noteworthy potential of the designed system as siRNA carrier. General conclusions regarding the works collected in this thesis are summarized in chapter six.