Self assembled multilayered supraparticles
Authors:   , Suresh Babu Agasthya 
Published: November 2024

[EMBARGOED UNTIL 08/01/2025] In this dissertation we push the boundaries of bioengineering with newly discovered interaction phenomena and present a viable supraparticle platform for biomedical applications. The remarkable ability of nature to form precisely structured assemblies through self-assembly and self-limitation offers inspiration to engineer functional nanomaterials. Supraparticles, formed by the controlled organization of nanoparticles, promise diverse applications in biomedicine, catalysis, environmental remediation, energy storage, and sensing tools. However, existing particle designs face limitations in aqueous synthesis and stability, lack of internal order, limited payload compatibility, lack of controlled release, and potential toxicity. This dissertation addresses these challenges through the development of a supraparticle platform with the following key features: (i) self-limiting self-assembly in water with internal order, (ii) stimuli responsive design, (iii) payload versatility, (iv) design for effective clearance, and (v) payload protection. Our solution, SAMS (Self Assembled Multilayered Supraparticles) represents a significant step forward in the controlled assembly of sub-5nm gold nanoparticles (AuNPs) in an aqueous environment, featuring an intricate 3D concentric arrangement. The synthesis involves the formation of a transitionary AuNP-THPC and lipidoid complex, stabilized subsequently by an organic matrix enabling rapid SAMS formation. Detailed characterization elucidates the distinct concentric arrangement within the SAMS with constant interlayer distance (4nm) regardless of overall SAMS size. To demonstrate their potential for biomedical applications, we successfully loaded siRNA into SAMS, exploiting the inherent cationic nature of lipidoids. These SAMS-siRNA demonstrated rapid uptake ([less than] 2 hrs), successful endosomal escape, remarkable transfection efficiency (99.87 [plus or minus] 0.04 percent), good spheroid penetration, efficient gene downregulation (97 [plus or minus] 2.8 percent) and disassembly within the cell ([less than] 24 hrs). SAMS were also capable of carrying larger nucleic acids, such as mRNA for overexpression and sgRNA for CRISPR-mediated genome editing in vitro. SAMS were well tolerated in mice at therapeutically relevant doses, and in vivo downregulation (DR) studies in PDX (28 percent DR at 194 [mu]g/kg siRNA-AXL) and CDX (36 percent DR at 194 [plus or minus] g/kg siRNA-YAP) lung cancer models affirm their gene-silencing capability. The dose-dependent downregulation in a lung cancer PDX model (16 percent and 28 percent DR at 97 and 194 [plus or minus] g/kg siRNA-AXL respectively) shows that there is potential to fine tune efficacy based on the need. We also outline our efforts to develop new clinically relevant patient derived organoids (PDO) and xenograft (PDX) NSCLC models to enable testing of platforms such as SAMS. Overall, this dissertation offers three important contributions to the field of material science and biomedical applications: (i) New interaction phenomena: between lipidoid and AuNP-THPC forming complexes, between lipidoid and gelatin forming nanoparticles, and between all three components forming a layered arrangement of gold nanoparticles in a concentric lamellar fashion, (ii) the loading and delivery of highly labile biomolecules (siRNA and mRNA) in the new supraparticle, and (iii) newly developed patient-derived organoids and xenografts for the testing of nanomaterial platforms.