Title: Engineering biomimetic formulations for drug and gene delivery
Description: Nanotechnology-based solutions have gained burgeoning attention in medical research, as compared with conventional therapeutic modalities, they offer advantages in efficacy, safety, and scalability. Researchers have been developing fluidic systems for nanoformulations over recent decades. Despite promising results, the clinical potential of the current nanosystems is still limited by insufficient cargo (drug and gene) loading, low production, high toxicity, low colloidal stability, unsatisfied bioavailability, and batch-to-batch variation. Flash-based self-assembly is a recently developed technology that can manufacture nanoformulations in facile, consistent, reproducible, and scalable manners. Due to the turbulent and dynamic flow generated in the mixing chamber, biomaterials self-assemble into uniform nanoparticles (NPs) through precipitation or complexation. We modified and manufactured a number of flash-based systems and evaluated their dynamic mixing profiles through simulation and empirical testing for polyplex formation and nanoparticle coating, as the dynamic fluidic control is the key for biomaterial complexation and nanoparticle coating, which provides better nanoparticle colloidal stability.

In Chapter 2, we formulated polyplexes and lipid-coated NPs with controllable size and enhanced colloidal stability by exploiting the dynamic mixing of the flash-based system. Bio-inspired nanosystems with engineered functions have been advancing the field of nanomedicine. Incorporating bio-inspired components can provide nanosystems with productive ways of interacting with their surroundings by diminishing nonspecific interactions or enhancing specific targeting. Membranes from different cell types, and even organisms, can be employed and merged to meet specific goals. We derived cell membranes from distinctive mammalian cell lines to improve nanosystems with smart biological interactions, such as preserving neo-antigens or enhancing specific targeting. Another potent property of utilizing cell membranes is that they provide NPs with colloidal stability. Recent studies have reported the use of cell membrane coating onto NPs in drug delivery, imaging, phototherapies, and detoxification.

The derived components from the original cell source bestow the NPs with their inherent functionality without additional complicated modulation. Cell membrane coating is a top-down technique that directly derives and harnesses the natural components, evading the technical and procedural challenges in bottom-up fabrication. However, current membrane coating techniques have problems of batch-to-batch variation and low production yield, which limits its potential for clinical translation. Taking advantage of flash-based self-assembly, we standardized and scaled up the cell membrane-coating process, which is difficult to achieve in bulk mixing approaches. The optimization of cell membrane coating was explored using various simulations. The time and cost for experimental design and optimization were reduced considerably. Cell membranes derived from tumor cells contain a rich source of tumor antigens. With the potential of cell membrane coating using flash-based self-assembly, we applied the produced cell-membrane-coated mesoporous silica nanoparticles (MSN) as a biomimetic nanovaccine for cancer immunotherapy in Chapter 3.

Oral delivery of drugs and genes is a relatively convenient, patient-friendly, and safe approach. Targeted and controlled oral delivery of active pharmaceutical ingredients (API) of biomimetic nanocarriers offers significant advantages in efficacy and safety compared to conventional modalities. Besides mammalian cells, the unique functionalities of other prokaryotic and eukaryotic cell types, such as bacterium and yeasts, were exploited for macromolecule delivery. Baker’s yeast, a common yeast strain closely associated with food preparation, contains valuable polysaccharides that were reported to specifically bind to the dectin-1 receptors on the specialized intestinal epithelial cells and monocytes. Exploiting the yeast’s cell wall is a biomimetic strategy when designing an oral carrier for targeted oral drug and gene delivery. We demonstrated that the specific recognition between the microfold cells (M-cells) of the small intestine and the polysaccharides on the yeast cell wall enhances the transport of yeast-based formulations across the gut epithelium and into the lymphatic tissues in chapter 4.

Utilizing the micron-sized yeast capsule or decorating a nanoparticle surface with processed yeast cell wall fragments, therapeutics were efficiently delivered to the target site through the oral path. The yeast-based formulations are biomimetic systems for targeted oral delivery of therapeutics. Taken together, the goal of this thesis is to close the gap between laboratory research and clinical translation by exploring the versatility and robustness of the developed flash technology, exploiting flash-based self-assembly for scalable production of the lipid and cell-membrane-coated nanosystems, and developing a relatively safe yeast-based drug and gene delivery platform.