Engineered Bovine Serum Albumin Protein-based  Antifouling Coatings for Bioengineering Applications
Creators: Zhao, Ziqian
Publisher: name: University of Alberta Library
Year: 2024

<p>Bioengineering and biomedical devices are extensively utilized in diagnostics, therapeutics, stomatology, and orthopedics, saving countless lives and experiencing surging demand due to the population aging. Yet, they face great challenges from irreversible biofouling and associated biocorrosion, causing uncontrollable and rapid device dysfunction. Integrating a biocompatible antifouling coating on device surfaces is vital to address these problems, where bovine serum albumin (BSA) protein-based coating with high-efficient biofouling resistance shows promise. However, limited functionalities and surface instability of BSA molecule greatly restrict its application scope and compromise the antifouling performance, respectively. Furthermore, there is no protein-based protective coating tailored to mitigate the severe fouling-accelerated biocorrosion for the widely used metallic implants. This thesis focuses on addressing these critical limitations faced by protein-based coatings through engineering protein with universal anchoring capability on different surfaces and on-demand functionalities, particularly with robust antifouling properties in complex biofluids and enhanced anticorrosion performance, for bioengineering and biomedical applications.<br>
Since the surface anchoring capability of BSA is the prerequisite of constructing coatings on substrates, it is first investigated through direct interfacial interaction measurements. It is found that the self-adaptive interfacial interactions of BSA to different substrates include hydrogen binding, hydrophobic force, electrostatic force, and other interaction forces. These interactions synergistically enable universal anchoring and controllable deposition of BSA proteins by tuning solution chemistry, such as pH, salinity, reactant concentration, and coating time. A methacrylate-conjugation method is developed based on the facile thiol-ene click-chemistry-initiated polymerization to customize the functionalities of engineered proteins (BSA@Polymer) for different working scenarios, such as enhanced antifouling, robust adhesion, and pH-stimuli drug delivery. With the universal anchoring capability and versatile functionalities, we ultimately achieve the construction of BSA-based coatings with on-demand functionalities on organics, inorganics, and metallics for various bioengineering and biomedical applications.<br>
A zwitterion-conjugated BSA protein coating is engineered based on the conjugation method developed in the first work through grafting sulfobetaine methacrylate (SBMA) segments on native BSA protein molecules for surface coating and antifouling applications in complex biological fluids. Unlike traditional synthetic polymers of which the coating operation requires arduous surface pretreatments, the engineered protein BSA@PSBMA (PolySBMA conjugated BSA) can achieve facile and surface-independent coating on various substrates through a simple dipping/spraying method. Interfacial molecular force measurements and adsorption tests demonstrate that the substrate-foulant attraction is significantly suppressed due to strong interfacial hydration and steric repulsion from the bionic structure of BSA@PSBMA, enabling coating surfaces to exhibit superior resistance to biofouling for a broad spectrum of species including proteins, metabolites, cells, and biofluids under complex biological conditions. <br>
To combat the biofouling-accelerated corrosion for metallic implants, especially for magnesium (Mg)-based biomaterials, a tooth-enamel-inspired, highly compact dual protection NaMgF3@BSA inorganic-protein (InorganicPro) coating is in-situ constructed on Mg surfaces through a BSA protein-facilitated reaction between sodium fluoride (NaF) and Mg substrate. The association of Mg ions and BSA establishes a local hydrophobic domain that lowers the formation enthalpy of NaMgF3 nanoparticles. This innovation generates finer nanoparticles, facilitating denser packing, consequently reducing voidage within the coatings by over 50% and reinforcing mechanical durability. Moreover, the incorporation of BSA in and on the coatings plays two synergistic roles: (1) sealing residual cracks within coatings, thereby promoting coating compactness and tripling anticorrosion performance, and (2) mitigating fouling-accelerated biocorrosion in complex biosystems with tenfold resistance against bio-foulant attachments, including biofluids, proteins, and metabolites. <br>
In summary, this thesis introduces an innovative approach harnessing native BSA proteins to create engineered proteins with extraordinary and tailored functionalities for biomedical applications, particularly with the robust antifouling and enhanced anticorrosion properties. This research elucidates the interfacial interaction mechanisms underlying BSA universal anchoring and outstanding antifouling phenomena and demonstrates a pioneering design strategy that leveraging proteins to alter inorganic reactions for enhanced performance. These advancements, grounded in fundamental surface science and applied protein-engineering technology, envision a flourishing development of novel protein-based coatings and materials in biomedical, chemical, food, and energy industries and hold potential to shape the trajectory of future nano-, bio-, and eco-technologies, paving the way for a more innovative, sustainable world. </p>