Lewis D. Blackman

Permeable Protein-Loaded Polymersome Cascade Nanoreactors by Polymerization-Induced Self-Assembly

Enzyme loading of polymersomes requires permeability to enable them to interact with the external environment, typically requiring addition of complex functionality to enable porosity. Herein, we describe a synthetic route toward intrinsically permeable polymersomes loaded with functional proteins using initiator-free visible light-mediated polymerization-induced self-assembly (photo-PISA) under mild, aqueous conditions using a commercial monomer. Compartmentalization and retention of protein functionality was demonstrated using green fluorescent protein as a macromolecular chromophore. Catalytic enzyme-loaded vesicles using horseradish peroxidase and glucose oxidase were also prepared and the permeability of the membrane toward their small molecule substrates was revealed for the first time. Finally, the interaction of the compartmentalized enzymes between separate vesicles was validated by means of an enzymatic cascade reaction. These findings have a broad scope as the methodology could be applied for the encapsulation of a large range of macromolecules for advancements in the fields of nanotechnology, biomimicry, and nanomedicine.

Confinement of Therapeutic Enzymes in Selectively Permeable Polymer Vesicles by Polymerization-Induced Self-Assembly (PISA) Reduces Antibody Binding and Proteolytic Susceptibility

Covalent PEGylation of biologics has been widely employed to reduce immunogenicity, while improving stability and half-life in vivo. This approach requires covalent protein modification, creating a new entity. An alternative approach is stabilization by encapsulation into polymersomes; however this typically requires multiple steps, and the segregation requires the vesicles to be permeable to retain function. Herein, we demonstrate the one-pot synthesis of therapeutic enzyme-loaded vesicles with size-selective permeability using polymerization-induced self-assembly (PISA) enabling the encapsulated enzyme to function from within a confined domain. This strategy increased the proteolytic stability and reduced antibody recognition compared to the free protein or a PEGylated conjugate, thereby reducing potential dose frequency and the risk of immune response. Finally, the efficacy of encapsulated l-asparaginase (clinically used for leukemia treatment) against a cancer line was demonstrated, and its biodistribution and circulation behavior in vivo was compared to the free enzyme, highlighting this methodology as an attractive alternative to the covalent PEGylation of enzymes.

Structural Determinants of the Stability of Enzyme‐Responsive Polyion Complex Nanoparticles Targeting Pseudomonas aeruginosa’s Elastase

Abstract Here, we report how the stability of polyion complex (PIC) particles containing Pseudomonas aeruginosa’s elastase (LasB) degradable peptides and antimicrobial poly(ethylene imine) is significantly improved by careful design of the peptide component. Three LasB‐degradable peptides are reported herein, all of them carrying the LasB‐degradable sequence −GLA− and for which the number of anionic amino acids and cysteine units per peptide were systematically varied. Our results suggest that while net charge and potential to cross‐link via disulfide bond formation do not have a predictable effect on the ability of LasB to degrade these peptides, a significant effect of these two parameters on particle preparation and stability is observed. A range of techniques has been used to characterize these new materials and demonstrates that increasing the charge and cross‐linking potential of the peptides results in PIC particles with better stability in physiological conditions and upon storage. These results highlight the importance of molecular design for the preparation of PIC particles and should underpin the future development of these materials for responsive drug delivery.

Palladium-polymer nanoreactors for the aqueous asymmetric synthesis of therapeutic flavonoids

Polymeric core–shell micelles incorporating a chiral palladium pyridinooxazoline catalyst are presented as nanoreactors for the aqueous asymmetric synthesis of flavanones, a class of flavonoids with therapeutic properties. Use of the nanoreactor was found to increase catalyst activity, enabling catalysis at room temperature, with low palladium loadings and without any additives.