Generation and Functionalization of Biodegradable Nanoparticles for Biomedical Applications

Abstract

Biodegradable nanoparticles are gaining increased attention because of their versatile applications in nanomedicine. The emergence of biodegradable magnetic iron oxide nanoparticles (MNP) as an easily synthesised, chemically stable and magnetically controllable nanomaterial has attracted widespread interests. Biomolecules can be incorporated into a single magnetic nanoparticle without significantly losing their functional properties, allowing a broad range of biomedical applications including cell-specific targeting, imaging, and functional enhancement of therapeutic agents. Cardiovascular diseases are leading causing of death worldwide, whilst the infection related antimicrobial drug resistance (AMR) has become a global burden in recent years. Vascular endothelial cells are the luminal layer of blood vessels and have important physiological functions. Dysregulation of endothelial cells involves in pathologies of a wide range of age related conditions including atherosclerosis, hypertension, stroke, diabetes, cancer and inflammatory responses. Antimicrobial peptides (AMP), on the other hand, represent promising alternatives to antibiotics for reducing antimicrobial drug resistance. Therefore, the aim of this thesis is to generate biodegradable magnetic iron oxide (Fe3O4) nanoparticles and create a technology platform to enable functionalisation of the nanoparticles with antibodies, nucleic acid and peptides, for future medical applications in areas such as cardiovascular diseases and antimicrobial resistance. Biodegradable magnetic iron oxide nanoparticles were produced based on a co-precipitation method and further functionalisation with sodium citrate, dopamine, and polyethylene imine (PEI). Material characterisation techniques such as FTIR, XRD, TEM and Zeta Potential were employed to characterise thoroughly the generated nanoparticles for further conjugation of biomolecules. We demonstrated that the citrate-functionalised magnetic nanoparticles (MNP@Cit) were successfully conjugated with antimicrobial cationic peptides, nisin and SMAP-29. The conjugation efficiency for nisin was highly efficient (~100%). Both nisin and SMAP-29 conjugated MNP@Cit nanoparticles have significant antimicrobial activities against S.aureus and E.coli. Next, we demonstrated effective conjugation of endothelium-specific anti-CD31 antibody onto MNP@Cit and dopamine-coated (MNP@DOPA) or citrate/PEI-modified (MNP@Cit@PEI) nanoparticles. Results showed that the CD31 antibody functionalised nanoparticles could be effectively delivered into human primary coronary artery endothelial cells (hCAECs) and receptor-dependent endocytosis played an important role in NPs@Ab delivery. The CD31-antibody functionalised nanoparticles could also be efficiently and specifically delivered into hCAECs when co-cultured with human primary artery smooth muscle cells (hCASMCs) under a flow condition (at shear stress 10dyn/cm2) that was generated by the ibidi flow system. Furthermore, both CD31 antibody and siRNA against GAPDH were successfully conjugated onto MNP@Cit@PEI. Targeted delivery of the GAPDH siRNA into HCAECs achieved successful knockdown of GAPDH gene expression. Moreover, non-targeted delivery of NOTCH3 siRNA into HCASMCs achieved a significant knockdown of NOTCH3 expression with much higher silencing efficency than the chemical transfection agent Lipofectamine 2000. To sum up, we have developed an efficient and cost-effective approach to produce and functionalised iron magnetic nanoparticles under ambient routine laboratory condition. The proof-of-concept study could facilitate large-scale production of the functionalised nanoparticles for potential targeted therapy and diagnosis of conditions like vascular diseases and beyond.

Date of Award	31 Dec 2020
Original language	English
Awarding Institution	The University of Manchester
Supervisor	Lin Li (Supervisor), Zhu Liu (Supervisor) & Tao Wang (Supervisor)