Drug delivery systems (DDSs) are emerging as an ideal class of cancer treatment candidates due to their potential advantages over the free drug counterparts with respect to relapse and severe side effects. In recent years, constant improvements have been implemented on DDSs, such as nanoparticles (NPs), microparticles and antibody-drug conjugates. However, some DDSs such as polymeric nanoparticles have known issues, limiting their use clinically. Specifically, DDSs lack of a sufficient encapsulation efficiency (EE) of the therapeutic(s) of interest, an appropriate release pattern (typically burst release or insufficient dose released at the site of action), low cellular uptake, and the accumulation in off-target organs such as liver and spleen. In addition to these, technical reproducibility issues and batch-to-batch variability still exists. This research project aims to develop and validate in vitro new minimally invasive DDSs, enabling a more effective release of the therapeutic of interest at the site of action. The first part of the research project focused on the use of microfluidics for the precise fabrication of poly(lactic-co-glycolic acid) (PLGA) NPs. Optimisation of fabrication parameters of a microfluidic system was therefore conducted to enable the control the fabrication of PLGA NPs with size in the range of 75 - 200 nm, limiting batch-to-batch variability issues, improving production efficiency, and enhancing scale-up of NP production. Following these results, a novel therapeutic compound (hydroxyl-FK866, which induces metabolic toxicity through prevention of nicotinamide adenine dinucleotide (NAD) recycling) was chemically conjugated to PLGA, and the hydroxyl-FK866-PLGA was used to manufacture NPs with the identified parameters, obtaining NPs with Z-average size of 128 ± 8 nm (polydispersity index < 0.2), ζ-potential of -14.8 ± 5.3 mV, EE of 98.6 ± 5.8%, drug loading > 2%. These NPs demonstrate the sustained release of hydroxyl-FK866 with a pH-dependent mechanism up to two months, without any burst release pattern. It was observed a faster release in basic conditions (pH 8.4) than in acidic ones (pH 6.4). Uptake of NPs and toxicity were tested using the human leukemia monocytic cell line (THP-1) and the human triple negative breast cancer cell line (MDA-MB-231). This portion of the research, reports on a novel method for the fabrication of polymeric NPs and to solve the associated problems of low EE and undesired release in conventional polymeric NPs used for DDSs. Finally, a NP-loaded hydrogels were formulated and characterized as local DDSs. Specifically, we successfully coated PLGA NPs with chitosan (CS) to obtain positively charged NPs exposing primary amines on their surface. Then, unmodified alginate and oxidized alginate were used to form hydrogels, where CS-coated/uncoated PLGA NPs were loaded for the sustained release of hydroxyl-FK866. We demonstrated that NPs are homogeneously dispersed across the alginate-based suspension before/after injection, and even after 3D printing in ionically crosslinked alginate hydrogels. Results also confirmed that the CS-coated NPs encapsulated in the hydrogel reflected in a much better NP/alginate interaction than the negative-charged NPs, because of the positively charge of CS-coated NPs, which could have the electrostatic interaction with the network of the negatively charged alginate hydrogel. Moreover, a higher level of interaction was observed between CS-coated PLGA NPs and oxidized alginate, where the primary amines in CS reacted with aldehydes group on oxidized alginate (Schiff’s base reaction) to form covalent links. Finally, in situ injectability of nanocomposite hydrogel system and the printability was assessed, respectively using rheological characterization and 3D printing methods. In specific, 3D printed structures were designed for the implant at the tumour (peritumoral) for the controlled sustained and local drug release of potent chemotherapeutic
Polymer-derived injectable drug delivery system for local and sustained hydroxyl-FK866 release
Bai, X. (Author). 1 Aug 2023
Student thesis: Phd