catalysts Article Deciphering the Effect of Microbead Size Distribution on the Kinetics of Heterogeneous Biocatalysts through Single-Particle Analysis Based on Fluorescence Microscopy Emilio Muñoz-Morales 1, Susana Velasco-Lozano 1, Ana I. Benítez-Mateos 2, María J. Marín 3, Pedro Ramos-Cabrer 4,5 and Fernando López-Gallego 1,2,5,6,* 1 Heterogeneous Biocatalysis Laboratory, Instituto de Síntesis Química y Catálisis Homogénea (iSQCH), CSIC-Universidad de Zaragoza, C/Pedro Cerbuna 12, 50009 Zaragoza, Spain;
[email protected] (E.M.-M.);
[email protected] (S.V.-L.) 2 Heterogeneous Biocatalysis Laboratory, CICbiomaGUNE, Edificio Empresarial “C”, Paseo de Miramón, 182, 20014 Donostia-San Sebastián, Spain;
[email protected] 3 Servicio General de Apoyo a la Investigación—SAI, Servicio de Microscopía Electrónica de Sistemas Biológicos, Universidad de Zaragoza, C/Pedro Cerbuna 12, 50009 Zaragoza, Spain;
[email protected] 4 Magnetic Resonance Imaging Lab, CICbiomaGUNE, Edificio Empresarial “C”, Paseo de Miramón, 182, 20014 Donostia-San Sebastián, Spain;
[email protected] 5 IKERBASQUE, Basque Foundation for Science, Maria Diaz de Haro 3, 48013 Bilbao, Spain 6 ARAID, Aragon foundation for Science, 50009 Zaragoza, Spain * Correspondence: fl
[email protected] Received: 2 October 2019; Accepted: 24 October 2019; Published: 28 October 2019 Abstract: Understanding the functionality of immobilized enzymes with spatiotemporal resolution and under operando conditions is an unmet need in applied biocatalysis, as well as priceless information to guide the optimization of heterogeneous biocatalysts for industrial purposes. Unfortunately, enzyme immobilization still relies on trial-and-error approximations that prevail over rational designs. Hence, a modern fabrication process to achieve efficient and robust heterogeneous biocatalysts demands comprehensive characterization techniques to track and understand the immobilization process at the protein–material interface.