Single-Particle Studies to Advance the Characterization of Heterogeneous Biocatalysts

Immobilized enzymes have been widely exploited because they work as heterogeneous biocatalysts, allowing their recovery and reutilization and easing the downstream processing once the chemical reactions are completed. Unfortunately, we suffer a lack of analytical methods to characterize those heterogeneous biocatalysts at microscopic and molecular levels with spatio-temporal resolution, which limits their design and optimization. Single-particle studies are vital to optimize the performance of immobilized enzymes in micro/nanoscopic environments. In this Concept article, we review different analytical techniques that address single-particle studies to image the spatial distribution of the enzymes across the solid surfaces, the sub-particle substrate diffusion, the structural integrity and mobility of the immobilized enzymes inside the solid particles, and the pH and O₂ internal gradients. From our view, such sub-particle information elicited from single-particle analysis is paramount for the design and fabrication of optimal heterogeneous biocatalyst.