Alginate Encapsulation of Bioengineered Protein‐Coated Polyhydroxybutyrate Particles: A New Platform for Multifunctional Composite Materials

Abstract

Immobilization and display of proteins is extensively used to enhance stability and performance of proteins for technical uses such as in biotechnology. Here, self‐assembled nonporous polyhydroxybutyrate (PHB) particles bioengineered to display proteins of interest are subjected to alginate encapsulation processes. The novel composite spheres are fabricated using ionotropic gelation methods. The immunoglobulin G (IgG) binding domain Z and organophosphate hydrolase (OpdA) are attached to PHB particles, and are examples for bioseparation and bioremediation applications, respectively. Alginate microspheres entrapping Z domain coated PHB particles enable flow‐through purification of IgG. Microsphere porosity is pH tunable and at acidic pH IgG is released from Z domains but retained within microspheres. OpdA‐PHB particles are functionally entrapped in alginate microspheres enabling flow‐through substrate conversion. Attachment of functional proteins to PHB particles enhances retention within the alginate microspheres. The hydrophobic PHB particle core within alginate beads provides payload for lipophilic substances, which adsorption kinetics are aligned with a pseudo‐second‐order kinetic model in agreement with the Freundlich isotherm model. This study describes the development of a multifunctional composite material platform based on alginate spheres encapsulating PHB particles that provide payload for lipophilic substances and can be engineered to display protein functions of interest.

Electrochemical Detection of Global DNA Methylation Using Biologically Assembled Polymer Beads

“…To achieve a more extensive interacting active area on the sensing surface, PHB nanobeads were directly adsorbed on the sensing platform to simplify our assay design by avoiding multi-step sensor fabrication processes that are usually associated with DNA hybridisation-based assays. PHB beads had been engineered to display IgG binding ZZ domains [30][31][32][33][34] in order to bind to specific 5mC antibody peroxidase conjugate, and the resulting antibody-coated beads were then tested for highly specific and efficient capture of methylated DNA on the modified electrode surface. In the presence of HRP and HQ, the electrode generated enhanced amperometric responses via the H 2 O 2 /HRP/HQ redox cycling system.…”

Polymeric nanoparticle vaccines to combat emerging and pandemic threats

“…9 ) [ 240 ]. In addition, these protein-coated PHB particles can be further encapsulated by hydrogels, such as alginate [ 243 ], to potentially enhance vaccine performance by enabling oral administration routes and/or by generating antigen depot effects. Escherichia coli ( E. coli ) is predominantly used as the microbial cell factories producing the particles [ 244 ], as it offers high volumetric productivity through high cell-density fermentation technology that had already been well-established for commercial biopharmaceutical production for decades [ 245 ].…”

Bioengineered Polyhydroxyalkanoates as Immobilized Enzyme Scaffolds for Industrial Applications

“…Apart from the inherent inconsistency of the PHA particles as outlined above, particulate carriers (<1 µm) are often prone to aggregation under various environmental conditions (e.g., pH, temperature, and ionic strength), which impairs substrate access to the enzymes (Zhang, 2014;Thoniyot et al, 2015) and which could adversely affect their performance in continuous flow processes. The non-porous nature of PHA particles and their tendency to aggregate will cause extensive back-pressure in flow-through applications (Ogura and Rehm, 2019). One innovative solution to overcome these issues is to encapsulate the functionalized PHA particles into a porous hydrogel matrix for efficient integration of enzyme-coated PHA particles into continuousflow bioprocesses.…”

“…We recently described an innovative approach that encapsulates functionalized PHA particles within a highly amenable anionic polysaccharide, alginate. The particle-hydrogel composite material was fabricated using the ionotropic gelation method with calcium ion as the crosslinker (Figure 3B) (Ogura and Rehm, 2019). Interestingly, the porosity of the alginate microsphere encapsulating functional protein-coated PHA particles could be controlled by pH during the fabrication process, showing the flexibility of this approach.…”

“…Interestingly, the porosity of the alginate microsphere encapsulating functional protein-coated PHA particles could be controlled by pH during the fabrication process, showing the flexibility of this approach. The various functional protein-coated PHA particles encapsulated within alginate microspheres showed either retained (e.g., organophosphorus hydrolase) or enhanced (e.g., immunoglobulin G-binding ZZ domain) activities in both batch and flow-through mode suggesting suitability for industrial applications (Ogura and Rehm, 2019).…”