Microfluidics-Based Biocatalyst-Product Separation for Continuous Enzymatic Processes. a Case Study on β-Lactam Antibiotics Manufacturing

Immobilizing an enzyme on a support often is essential for downstream separation of the biocatalyst from a product and retaining the valuable enzyme in many enzymatic processes. This is particularly true in the case of continuous enzymatic manufacturing processes where the enzyme needs either to be retained in the reactor or separated from the product downstream and recycled back to the reaction vessel. This becomes challenging when the product is in solid form, e.g., crystals, necessitating the separation of two types of solid particles, biocatalyst and the crystalline product. This is the case for the continuous synthesis and crystallization of β-lactam antibiotics using the enzyme Penicillin G acylase (PGA) [1].

In this contribution, we propose a 3D-printed microfluidics-based device for downstream separation of the biocatalyst from the crystalline antibiotic product. Microfluidics is a technique characterized by the precise manipulation of fluid dynamics at the microscale and has shown a great promise for industrial processing applications. Among microfluidic devices, inertial microfluidics has experienced massive growth due to their high throughput, automation, operational simplicity, and low cost [2]. In such a device, particles with different sizes are separated by taking advantage of inherent inertial lift and drag forces. Inertial microfluidics can be employed by various channel shapes and structures; spiral channels are frequently used for the aim of high-throughput particle focusing by reduction of lateral migration positions and they can be an ideal candidate for this particular application. Here, we focus on the separation of high aspect ratio crystals from spherical biocatalyst particles. The efficiency of the separation for different product and catalyst sizes, and potentials/challenges for scaling up the proposed separation strategy will be discussed.

[1] McDonald, M. A., Bommarius, A. S., Grover, M. A., & Rousseau, R. W. (2019). Continuous reactive crystallization of β-lactam antibiotics catalyzed by penicillin G acylase. Part II: Case study on ampicillin and product purity. Computers & Chemical Engineering, 126, 332-341.

[2] Moloudi, R., Oh, S., Yang, C., Teo, K. L., Lam, A. T. L., Warkiani, M. E., & Naing, M. W. (2018). Inertial-based filtration method for removal of microcarriers from mesenchymal stem cell suspensions. Scientific reports, 8(1), 1-10