Engineering of bioorthogonal polyzymes through polymer sidechain design

Abstract

Synthetic polymer scaffolds can encapsulate transition metal catalysts (TMCs) to provide bioorthogonal nanocatalysts. These 'polyzymes' catalyze the in situ generation of therapeutic agents without disrupting native biological processes. The design and modification of polymer scaffolds in these polyzymes can enhance the catalytic performance of TMCs in biological environments. In this study, we explore the hydrophobic design space of an oxanorborneneimide-based polymer by varying the length of its carbon side chain to engineer bioorthogonal polyzymes. Activity studies indicate that modulating the hydrophobicity of the polymer scaffold can be used to enhance the catalyst loading efficacy, catalytic activity, and serum stability of polyzymes. These findings provide insight into the structural elements contributing to improving polymeric nanocatalysts for a variety of applications.

Keywords: bioorthogonal catalysis; nanocatalysts; polyzymes.

Figure 1.

Polyzyme performance depends on the structure of the polymer scaffold. Increased hydrophobicity of the scaffold leads to enhanced activity and protection of the catalyst in the presence of serum proteins.

Figure 2.

a) Preparation of polyzymes using varying feed ratios of Pd TMC and different PONI-C_n-Guan scaffolds, b) polyzyme catalyzed uncaging of pro-Rho to fluorescent rhodamine 110, c) quantification of Pd per polymer (nmol/mg) measured by ICP-MS.

Figure 3.

Reaction kinetics of a) different polyzyme species at constant feed ratio (1.0 mg/mL Pd TMC) and b) polyzymes fabricated using PONI-C₇-Guan with varying feed ratio (0.5/1.0/1.5 mg/mL Pd TMC).

Figure 4.

a) K_m, b) K_cat, and c) K_cat/K_m values of PONI-C₇-Guan-based polyzymes with respective error bars.

Figure 5.

Confocal microscopy images of HeLa cells incubated with 300 nM of C₇-1.0-PZ and 50 μM pro-Rho. Nuclei were stained by Hoechst 33342. Scale bars, 20 μm.