Scalable Custom NanoPak-C Monolith Media for Improved Biologic Purification

Millennial Scientific has expanded its manufacturing capabilities to produce scalable custom 3D monolith

Figure 1. Digital images of NanoPak-C All Carbon monoliths of different sizes.

media. These monoliths, assembled using spherical NanoPak-C All Carbon microbeads, are specifically designed for the purification of large biologics (Figure 1). This includes protein complexes, viruses, and even whole cells or organelles, at high speed and efficiency—capabilities that are often unattainable with conventional microbead media, even those with large pores.

Monoliths are large, single pieces of porous material, with dimensions ranging from millimeters to centimeters.

Figure 2. Depiction of (top image) a conventional microbead-packed column, and (bottom image) a monolith column.

In a column packed with spherical microbeads, approximately 30% or more of the total volume consists of interstitial voids [1]. These gaps (Figure 2, top image) between the microbeads do not contribute to the separation process, yet they occupy a significant amount of space.

Monoliths eliminate these interstitial voids (Figure 2 bottom image). Their structure contains channels that have both small and large pores. The larger pores facilitate the rapid transport of the analyte through convective flow across the entire stationary phase, thus allowing for better control of flow rates and minimizing column backpressure. Meanwhile, the smaller pores enhance the surface area, improving separation efficiency. Monolithic chromatography is characterized by exclusively convective flow. As a result, the sizes of the large and small pores are significantly larger (≥500 nm) than those found in conventional microbead media (≤40 nm), allowing for effective convective transport [2].

A key differentiator of our monoliths, compared to other commercially available monoliths, is the assembly of NanoPak-C spherical microbeads into a continuous three-dimensional network, forming a cohesive monolith structure.

Commercially available monoliths are manufactured through the direct polymerization of starting materials, such as organic polymer monomers, ceramics, or silica, into molds of suitable shape and size [2]. This process yields a single, continuous, and porous structure. A crucial objective in the monolith fabrication technique is to independently engineer both large and smaller pores within a single monolith. The larger pores facilitate rapid flow, allowing for the control of desired flow rates and minimizing column backpressure. The smaller pores increase the surface area, improving separation efficiency.

However, the direct polymerization method faces challenges when it comes to producing large-scale monoliths with a uniform pore size distribution or achieving independent control over the engineering of large and small pores. A slight change in polymerization temperature can affect the pore size distribution. Unfortunately, the exothermic nature of the polymerization process makes it impossible to avoid temperature increases within the monolith. This effect becomes more pronounced as the monolith size increases [3]. Changes in pore structure can cause inconsistent and unpredictable separation performance. The variability can depend on the specific application, analytes, and operating conditions. Furthermore, reproducibility between different batches or columns is often more challenging compared to traditional packed columns. Our approach aims to address these issues.

Our monolith fabrication process opens up unique possibilities for engineering and optimizing its structure.

Tailoring Material Properties: We begin by creating microbeads that can be chemically modified to enhance specific interactions needed for the separation of various analytes. These microbeads also enable smaller pore sizes, which enhance separation efficiency.

Porosity Control: Next, we assemble the microbeads into 3D structures with large inter-microbead pore channels that facilitate convective flow. This strategy supports layer-by-layer 3D printing, providing better control over parameters such as temperature, which significantly affect the pore structure.

This approach enables us to exert greater control over the media’s properties (such as stability, binding capacity, and batch-to-batch reproducibility) and its performance (including pharmaceutical purity and yield) tailored to specific pharmaceuticals. Our design focus is to allow the following benefits of monoliths for the separation of large biologics.

Truly Convective Flow: Monoliths exhibiting convective mass transport, regardless of whether the analytes are small molecules or large biomolecules, such as proteins or viruses. Convective transport leads to uniform migration velocities for solutes of different sizes, maintaining sharp resolution that is largely independent of flow rate.

High Binding Capacity and Speed: Monoliths displaying optimum dynamic binding capacities for large molecules and enabling much faster binding and elution because equilibrium is reached quickly by convection.

Flow Rate Independence: Resolution and capacity of large molecules in monoliths remaining relatively constant across a wide range of flow rates.

Lower Shear and No Eddy Dispersion: Monoliths exhibiting laminar flow with no void spaces or interstitial eddies, which reduces shear stress and product degradation—critical for sensitive and labile biologics. There is also less risk of aggregate formation or loss of biological activity in fragile biologic molecules.

For more information or to request samples, please email us at inquiry@millennialscientific.com, call us at 855-388-2800, or complete our online form.

References

[1] M. Jacoby, Monolithic Chromatography, Chemical & Engineering News (CEN) 84(50) (2006) 14.

[2] F. Svec, C.G. Huber, Monolithic Materials: Promises, Challenges, Achievements, Analytical Chemistry 78(7) (2006) 2100-2107.

[3] A. Podgornik, M. Barut, A. Štrancar, D. Josić, T. Koloini, Construction of Large-Volume Monolithic Columns, Analytical Chemistry 72(22) (2000) 5693-5699.