Hybrid Lipid Nanoparticle Platforms for Multifunctional Therapeutic Delivery: Integrating Magnetic, Inorganic, and Scaffold Systems to Overcome Biological Barriers

Abstract

Background Lipid nanoparticles (LNPs) have become the leading non-viral platform for nucleic acid delivery, validated clinically by Patisiran (2018) and the mRNA COVID-19 vaccines. However, standard LNP formulations are heavily biased toward hepatic delivery and are ill-suited for applications requiring extrahepatic targeting, sustained local expression, or penetration of resistant bacterial biofilms. This doctoral thesis investigates how hybridizing LNPs with inorganic materials and biomaterial scaffolds can overcome these fundamental biological barriers. Chapter 2 — Magnetic LNPs for Organ-Specific mRNA Delivery Carboxylated superparamagnetic iron oxide nanoparticles (SPIONs) were co-encapsulated with mRNA into LNPs to create magnetic LNPs (mLNPs). In mice, applying an external magnetic field over the thoracic region during intravenous administration measurably increased luciferase bioluminescence in the heart and lungs while modestly reducing hepatic and splenic accumulation. This provided a proof-of-concept that physical magnetic guidance can partially override the liver tropism inherent to conventional LNPs. Limitations include the modest magnitude of redirection, persistent liver clearance, and the fact that experiments were conducted in healthy animals without disease-relevant pathophysiology. Chapter 3 — LNP-Hydrogel Platform for Sustained VEGF mRNA Delivery To address the rapid clearance of LNPs from injection sites, VEGF mRNA-loaded LNPs were embedded within a collagen-fibrin hydrogel containing human umbilical vein endothelial cells (HUVECs) and pericytes. The hydrogel's small pore size physically retained LNPs, creating a "transfection depot" that prolonged VEGF protein release over at least seven days. This sustained expression drove significantly more extensive CD31-positive microvascular network formation compared to controls, demonstrating a promising strategy for tissue-engineered vascularization — with urethral reconstruction as the target clinical application. The platform was validated in vitro only; effects of fluid flow, oxygen gradients, and immune integration remain to be assessed. Chapter 4 — Chiral Gold Nanocluster-Loaded LNPs for Biofilm Eradication To tackle the challenge of antibiotic-resistant S. aureus biofilms, ultrasmall chiral histidine-stabilized gold nanoclusters (AuNCs, <2 nm) were encapsulated within cationic LNPs. The system exploits dual mechanisms: the cationic LNP shell promotes electrostatic adhesion to the anionic biofilm matrix, while the AuNCs generate reactive oxygen species (ROS) for oxidative bacterial killing. In vitro, AuNC@LNPs outperformed free nanoclusters in reducing adherent biomass. In a murine subcutaneous implant infection model, a single perilesional injection reduced bacterial burden by approximately 2.6 log CFU versus vehicle. Tolerability constraints at higher doses and the absence of long-term data represent key translational hurdles. Chapter 5 — Synthesis and Perspectives The thesis concludes that the core LNP architecture is highly adaptable — capable of integrating magnetic nanoparticles, forming hydrogel depots, or encapsulating inorganic antimicrobial agents without losing its fundamental delivery function. Crucially, each hybrid modification addresses a specific barrier without resolving all remaining challenges (e.g., endosomal escape efficiency, immune activation, hepatic clearance). The work is exploratory in nature, conducted with small sample sizes and short observation windows, and sets the stage for follow-up studies in disease-relevant models and, ultimately, clinical translation.