See also Ion Exchange Chromatography and particularly types of resins

Mixed Mode Chromatography involves the use of solid phase chromatographic supports that employ multiple chemical mechanisms to absorb proteins or other solutes. Examples include chromatographic supports that exploit combinations of two or more of the following mechanisms: anion exchange, cation exchange, hydrophobic interaction, hydrophilic interaction, hydrogen bonding, pi-pi bonding and metal affinity. Mixed mode chromatography supports provide unique selectivities that cannot be reproduced by single mode chromatography methods such as ion exchange, but method development is complicated, unpredictable, and may require extensive resources, as exemplified by hydroxyapatite which is a crystalline miner of calcium phosphate (US7999085).

Multi-modal chromatography is a general term that encompasses all forms of separations in which multiple chromatographic mechanisms are deliverately used. This can be accomplished by attaching two or more chemically different ligands that interact with the sammple molecules in different ways. It can also be achieved by utilizing one type of ligand able to interact with the target molecule through different intermolecular forces. (Johansson, J. Chromatogr A, 1016(1), 2003, pp. 35-49).

Advantages and Disadvantages

Mixed mode chromatography provides unique selectivities that cannot be reproduced by single mode chromatography methods such as ion exchange. It provides potential cost savings, longer column lifetimes and operational flexibility compared to affinity based methods. However, the development of mixed mode chromatography protocols can place a heavy burden on process development since multi-parameter screening is required to achieve their full potential. Method development is complicated, unpredictable, and may require extensive resources to acheive adequate recovery due to the complexity of the chromatographic mechanism. (Nti-Gyabaah, US14/355014). 

unpredictability:

Mixed mode represent a broad and increasing diversity of ligands that exploit the combined functions of two or more chemical mechanisms. The influence of their primary mechanisms can be demonstrated fairly easily, for example, electrostatic and hydrophobic interactions, but the practical contributions and control of secondary functionalities are poorly understood, including metal coordination, pi-pi bonding, hydrogen bonding, and van der Waals forces. These introduce a strong element of unpredictability that is compounded by variations in ligand density and physical configuations among ligands of similar chemical character. (Pete Gagnon, J. Chromatography A 1221 (2012) 57-70)

Mixed-mode chromatography/ multi modal chromatography or in connection with a specific procedrue “hydrophobic charge induction chromatography” involves interaction of at least two principles; hydrophobic interaction and ion exchange or metal affintiy itneraction and ion exchange. Mixed-mode chromatography provies less predictable selectivities that cannot be reproduced by a single mode chromatogrpahy method such as ion exchange of hydrophobci interaction chromatography. Positively charge hydrophobi ligands below to the group of anion exchanger mixed-mode (for example CaptoAdhere) and the negatively charged ligands below to teh caiton exchanger mixed-mode (for example Capt MMC). Some mixed-mode media have zwitterionic character (for example Bakerbond ABx). Other mixed-mode media possess hydorphobic ligands which are ionisalbe and convert form uncharged to postivley charged by lowering the pH (for example MEP HyperCel). Finally, hydroxyapatite and fluroapatite media hav emroe complex mixed-mode fucntions by possessing positively charged calcium ions and negatively charged phosphate groups). (Zoltan, US 20220194981)

Types of Mixed Mode Chromatography Media/Supports See outline

Particular Types of Proteins Purified

Antibodies: See “antibody purification” and “mixed mode”

Prion Proteins:

Gilljam (WO2009/024620) discloses using a multimodal chromatographic material for the purification of a target protein by setting buffer conditions so that the protein is bound whereas prions do not bind followed by eltuion of the target protein suing an elution buffer with alcohols such as mono or dihyroxyalkanols (e.g., ower aliphatic alcohols such as methano, ethano, propanol) or by admending the pH or ionic strenght of the buffer. In one embodiment the elution buffer contains ethylene glycol (45-55%) and/or sodium chloride.