**Microfluidic Multiple Chamber Chip Reactor Filled with Enzyme-Coated Magnetic Nanoparticles**

Ferenc Ender, Diána Weiser and László Poppe

Additional information is available at the end of the chapter

http://dx.doi.org/10.5772/62512

#### **Abstract**

In this chapter, a novel microfluidic device (MagneChip) is described which comprises microliter volume reaction chambers filled with magnetically fixed enzyme-coated magnetic nanoparticles (*ec*MNPs) and with an in-line UV detector. In the experiments, MNPs with phenylalanine ammonia-lyase (PAL)—an enzyme which catalyzes the deamination of l-phenylalanine (Phe) to (E)-cinnamate in many organisms—immobi‐ lized on the surface were applied as biocatalyst to study the characteristics of the MagneChip device. In the reaction chambers of this microfluidic device, the accurate in situ quantization of the entrapped MNPs was possible using a resonant coil magneto‐ meter integrated below the chambers. Computational fluid dynamics (CFD) calcula‐ tions were used to simulate the flow field in the chambers. The enzyme-catalyzed biotransformations could be performed in the chip with excellent reproducibility and of repeatability. The platform enabled fully automatic multiparameter measurements with a single biocatalyst loading of about 1 mg PAL-*ec*MNP in the chip. A study on the effect of particle size and arrangement on the catalytic activity revealed that the mass of *ec*MNPs fixed in the chamber is independent of the particle diameter. Decreasing the particle size resulted in increasing catalytic activity due to the increased area to volume ratio. A binary mixture of particles with two different particle sizes could increase the entrapped particle mass and further the catalytic activity compared to the best uniform packing. The platform enabled a study of biotransformation of L-phenylalanine and five unnatural substrates by consecutive reactions using same PAL-*ec*MNP loading. With the aid of the platform, we first demonstrated that PAL can catalyze the ammonia elimination from the noncyclic propargylglycine as substrate.

**Keywords:** Magnetic nanoparticles, Magnetic chip reactor, Microfluidic reactor, Enzyme reaction, Phenylalanine ammonia-lyase

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