| Περίληψη: | Combining the functions of the prolonged systemic circulation, enhanced tumor targeting and specific intracellular drug release is vital for small molecule drug delivery as well as the nucleic acid formulations. Here, we report a new approach to prepare silica nanoparticles based on self-catalyzed ring-opening polymerization of PDMS chains utterly simplifying the design of multifunctional nanoparticles in a single step. Initially, we have synthesized siloxane modified peptide ligands, silylated fluorescein (si-FITC) and silylated PEG (si-PEG) monomers. Accordingly, Methotrexate (MTX) was used as an anticancer drug model to conjugated to a PEG linker (si-PEG-F-MTX); cyclic RGD peptide (si-PEG-3F-cRGD) was also incorporated to the nanoparticles for active targeting especially towards αvβ3 integrin-rich cancer cells. In an aqueous medium, functionalized PDMS polymer, with an optimized ratio of monomers, self-assembled to form nanoparticles ranging in size 100-120 nm which was confirmed by DLS, NTA and TEM measurements. Fluorine nuclear magnetic resonance (F-NMR) method revealed the incorporation yield thanks to the fluorine (F) atoms in the design of the monomers. The cytotoxic activity of MTX-NPs was investigated on A375 human cancer cell line. Importantly, our first results highlighted that MTX-NPs presented a significant cytotoxic activity on the cancer cells, whereas control-NPs (cRGD-NP without MTX) had no cytotoxic effects at tested concentration.
Preparation method was also applied to create a non-viral gene delivery vector. Siloxane modified K4H4 peptide was employed to form siRNA polyplexes. The sol-gel polymerization of the peptides was conducted in the presence and absence of siRNA. With siRNA in access, the polyplexes were directly formed in situ, in the parallel pre-formed si-K4H4 polymer was complexated with siRNA after its polymerization was completed. The polyplex formations were confirmed by agarose gel retardation assay for both methods. The findings clearly suggest that full-complexation of in situ siRNA and si-K4H4 resulted in lower nitrogen: phosphate (N/P) ratio compared to the pre-formed polyplex preparation. This result demonstrates that siRNA might be playing a role in polymerization kinetics driving the complexation electrostatically and aiding the covalent bonding of siloxanes. Taking into consideration this outcome, polyplexes were identified in terms of morphology, size and zeta potential establishing the fundamental basis of in situ forming highly stable PDMS polyplexes for the in vivo applications in the near future.
In our study, PDMS-NPs were functionalized with targeting ligands, imaging agents and stealth characteristics with the possibility of controlled release of drugs in a balanced composition. Our straightforward approach showed great potential for the development of novel multifunctional small molecule drug delivery for cancer-targeting and well-protected siRNA vectors with definite physicochemical properties.
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