3D Printed Microfluidic Chromatographic Column for Fast Downstream Processing Development

3D printing is emerging as a promising fabrication technique for microfluidic devices. In this work, this technology was exploited in the development of a microfluidic chromatographic column with nominal volume of 54 µL. The microcolumn was packed with a cation exchange resin and characterized, using potassium iodide as a tracer, in terms of porosity (ε = 0.72), plate number, and asymmetry factor (0.8 < A_S < 1.8 for flowrates >50 µL/min). To showcase the potential of this microdevice, it was exploited in the characterization of the chromatographic behavior of lysozyme. The measured saturation capacity (q^∞= 88.14 g/L_resin at 340 cm/h) was in line with the manufacturer declaration (85-135 g/L at <500 cm/h). In addition, the effect of NaCl at different concentrations on the protein adsorption isotherm was characterized, demonstrating a Langmuir to anti-Langmuir transition at concentrations ≥300 mM. The axial dispersion coefficient was finally determined ( $D_{AX}$ = 6.7 · 10^-9 m²/s). In this way, the mcirofluidic column allowed to develop a comprehensive mechanistic model describing the transport of lysozyme in the chromatographic medium using only 30 µL of resin and <1 g of protein, addressing the issue of limited availability of biomolecules and streamlining the process development.