Self-assembly is the process in which the constitutive components of a system spontaneously organize into ordered patterns or structures driven by non-covalent interactions. Crystallization is the acme of self-assembly. The self-assembly of biomacromolecules plays a crucial role in many industrial and biological processes. However, the control of bio-macromolecular self-assembly can be challenging due to the complex structure of the self-assembled materials. In this thesis, two different strategies to improve control over bio-macromolecular self-assembly are investigated for different engineering applications.

First, improved molecular self-assembly of DNA into origami nanostructures is achieved through a modular design framework. The construction of conventional DNA origami is expensiv...[ Read more ]

Self-assembly is the process in which the constitutive components of a system spontaneously organize into ordered patterns or structures driven by non-covalent interactions. Crystallization is the acme of self-assembly. The self-assembly of biomacromolecules plays a crucial role in many industrial and biological processes. However, the control of bio-macromolecular self-assembly can be challenging due to the complex structure of the self-assembled materials. In this thesis, two different strategies to improve control over bio-macromolecular self-assembly are investigated for different engineering applications.

First, improved molecular self-assembly of DNA into origami nanostructures is achieved through a modular design framework. The construction of conventional DNA origami is expensive due to the requirement for hundreds of staple strands with unique sequences. In this novel design framework, a disk-like basic structure with irregular crossover spacing and structure modifications based on a rectangular basic structure are designed and characterized. The novel design framework is simple and cost-effective compared to the conventional framework, as the resulting structures are designed via modular blocks and only a subset group of staples needs to be changed to construct versatile structures based on basic structures.

Second, the assembly of therapeutic protein molecules into crystalline structures can be used for improved purification and product formulation in the biopharmaceutical industry. Protein crystallization is generally more difficult compared to the crystallization of small molecules, which is attributed to the difficulty of creating the stable three-dimensional orientation of protein molecules. Furthermore, crystal quality attributes such as shape and size distribution need to be tailored for specific therapeutic applications. The current paradigm of batch crystallization in the pharmaceutical industry is not well suited to deliver such flexibility. Therefore, novel process concepts are needed to reliably produce protein crystals with optimal properties for a given application. In this thesis, a novel process strategy based on a slug flow crystallizer operated in continuous mode is developed to deliver inhalable insulin crystals that can be a potential source of long-acting insulin with enhanced stability. A high supersaturation is generated by a combined cooling and pH shift. The slug flow crystallizer allows for an insulin recovery of over 90% with a residence time of less than 1 hour. Most of the particles obtained under the optimal conditions appear crystalline and the startup time is fast. Then, the novel continuous crystallization step is integrated with spray drying to deliver a dry powder that is suitable for pulmonary drug delivery in a single process. Spray drying of the suspension at the crystallizer outlet leads to a mixture of insulin crystals and small particles of nonvolatile compounds. The insulin crystals remain intact after spray drying and in vitro characterization shows promising aerosol performance of the dry powder for inhalation. Lastly, the effect of temperature cycling in continuous protein crystallization in a slug flow crystallizer is investigated regarding the mean particle size, span of CSD, protein recovery, and degree of agglomeration. Particle agglomeration is a common drawback of fast protein crystallization in a tubular reactor, the results in this thesis show that temperature cycling can lead to reduced agglomeration and a comparable protein recovery in comparison to the conventional isothermal operation, which can intensify continuous protein crystallization.