Anion exchange and hydrophilic interaction: 

Negatively charged mixed mode ligands below to the cation exchanger mixed mode (for example CaptoAdhere) (Melinda, US 20170058019)

Examples include Capto-QTM which is a strong anion exchange and is a trademark of GE Healthcare Bio-Sciences. 

Polyethyleneimine derivatized polymeric media:

Deorkar (US 2008/0203029) discloses useful mixed mode chromatographic media for bioseparations whcih media polymeric includes particles dervivatized with polyethyleneimine (PEI) which are further funcitonalized with appropriate reactants. Examples of polyyric anyhdride and akly chlorides. In one embodiment, an anion excahnged with mixed primary and secondary and tertiary amine sites is prepared by reaction polyethyleneimine with a polymeric support bearing epoxy or halo groups such as chloro, boromo, iodo groups. Such polymeric support can be any suitable synthetic polymer or natural polymer resin such as poly(meth)acrylate, cellulose.  Resin particle suitable for derviatizaiton with polyethyleneimine includes cellulose, agarose, eopoxidized or halogenated polystyrenes. Examples of suitable functionalizaiton reagents for reaction with the PEI surface derivatized polyemeric resin partciles include anyhdrides such as cyclic carboxylic anyhdrides such as glutaric and succinic anhydrides, unsatured carboxylic anhydrides such as maleic meta-bisulfite, alkyl chorides or anhydrides such as butryl chloride.  Examples of such commerically avaialble resins are Tosoh Biosciences Toyopeark AF-eopxy 650M apoxy activated Sepharose 6B. These materials can be reacted with one of the teminal amino group of polyethyleneimine of various molecular weights through the formation of chemically stable alpha-hydroxy amino groups. In one embodiment, the mixed mode media having weak anion, weak cation and strong cation sites were prepared by reacting the EEI derivtized polymer with an unsaturated carboxylic acid anyhdride followed by sulfunation.

Anion and hydrophobic: 

Polyamines with Hydrophobic Group:

Engstrand (US 2007/0259453) discloses a method of separating antibodies using a multi-modal separation matrix to adsorb undesired compounds. The multi-modal separation matrix includes first groups which are capable of interacting with negatively charged sites of the target compoudns and second groups, which are capable of at least one interaction othern than charge-charge itneraction with said target compounds. In one embodimetn, the first anion-exchanging groups are strong anion exchanges such as qin that the groups remain charged within a wide pH range. In another embodiment, the first groups are weak ion exchanges in that they are charged at certain pH values but may loose charge by a pH switch. The second groups may give electron acceptor-donor interactions (e.g., hydrogen-bonding, dipole-dipole)  and/or hydrophobic and/or hydrophilic interactions. The functional groups may be present on the same ligand or on different ligands. In one embodiment, the the ligands are coupled to the support via their frist groups, such as via amines resulting in quaternary amines. 

Johansson (US Patent No: 6,702,943) discloses a method for removal of a target substance by adsorption to a matrix carrying a pluality of lgidnas taht include anion-exchaning groups and a hydrophobic structure. 

Matsumoto, (US 2015/0344520; see also US Patent Applicaiton No: 16/349,617, published as US 2019/0345194) discloses a chromatography media obtained by adding polyamine to a base media containing porous particles and then modifying amino groups in the polyamine with a hydrophobic group has excellentsalt tolerance and excellent adsorption. In particular, the chromatography media contains a base media haivng porous particles and a polyamine bonded with the base media wherein 20-40% of amino groups in the polyamine is modified with a hydrophobic group. The polyamine is selected from the gorup of polyallylamine, polyvinylamine, chitosan, polysine, polyguanidine and polyornithine. 

Commerical Examples:

–Capto adhere: is a mixed mode resin, a combination of anion exchagne and hydrophobic interaction. It can be operated in flow through mode where the antibody does not bind but the contaminante does bind. It is commercially available from GE Healthcare Life Sciences (Shaban, US 14/809,211). 

Capto adhere is a strong anion exchanger with multimodal functionality that gives a different selectivity compared to traditional anion exhangers. The Capto adhere ligand, N-Benzyl-N-methyl ethanol amine, exhibits many functionalities for interaction. The most pronounced are ionic interaction, hydrogen bonding and hydrophobic interaction. Capto adhere is designed for post Protein A purification of mAbs. Removal of leached Protein A, aggregates, HCS, nucleic acids and viruses is performed in flow through mode. The medium is based on a rigid high flow agarose matrix that allows high flow velocities to be used. (GE Healthcare Life Science, Instructions 28-9064-05AC Affinity Chromatography Capto adhere). 

Commercial examples include Capto-Adhere which is a multimodal anion exchange and a trademark of GE Bio-Sciences. Capto Adhere is a mixed-mode chromatography support which exploits a combination of anion exchange and hydrophobic interaction functionalities (US 8,188,242). Its ligand, N-benzyl-methy ethanol amine, contains anion exchange, hydrophobic and hydrogen bonding interaction groups. It is a strong anion exchanger with a phenyl group for hydrophobic interactions and a hydroxyl group for hydrogen bonding. The Capto adhere ligand (N-Benzyl-N-methyl ethanolamine) exhibits multiple modes of protein-interactive chemistries, including ionic interaction, hydrogen bonding and hydrophobic interaction. The multimodal functionality of the resin confers it with an ability to remove antibody dimers and aggregates, leached prtoein A, host cell proteins (HCP), antibody/HCP complexes, process residuals and viruses. The resin is typically used in flow through mode in the context of production scale polishing step employing operational parameters designed to ahve the mAb pass directly through the column while the contaminants are adsorbed. Nti-Gyabaah US14/355014

Generic conditions for use of multimodal anion exchangers such as CAPTO adhere do not exist. Specific conditions must be developed for each protein. The recomended method development procedure consists of evaluting various combinations of pH and sodium chloride concentration in the hope of identifying conditions that preferentially favor retention of aggregates (US 2011/0166332).

Gagnon (US 2011/0166332 and WO2010030222) discloses a method of separating at least one intact non-aggregated protein (e.g., an IgG antibody) form a liquid preparation by contacting the preparation with a multimodal anion exchanger sucha s CAPTO-adhere in the presence of one or more species of protein excluded zwitterions such as glycine.Boschetti (WO2004/024318) discloses mixed mode ligands which comprises a cyclic group which can be a monocyclic group or a polycyclic group such as a aromatic group that is a cylic hydrocarbon containing only unsaturated carbon bonds to give an aromatic system. While any aromatic group can be used, suitable aromatic groups typically have one, two or three aromatic rings. Illustrative aromatic groups are phenyl and its substituted derivatives such as tolyl and xylyl. Bicycl

–MEP HyperCel is a commercially available example of a combination of anion exchange and hydrophobic interaction functionalities (US 8,188,242). The spearation  is based on its pH dependent ionizable dual mode hydrophobic ligand design. In the purificaiton of a monoclonal antibody, for example, IgG adsorbs to the MEP ligand mianly through hydrophobic interactions under physiological buffer conditions. Desorption is through electrostatic repulsion between positivley charged IgG molecules and ionizable pyridine ring of the ligand when the buffer pH is decreased to close to or below the ligand pKa of 4.8, which the ligand is positively charged. See also “HCIC” under Antibody purification schemes.

Other commercial examples include MEP-Hypercel and Capto Adhere. Ma (US14208043)

Anion exchange + hydrophobic interaction + hydrogen bonding and pi-pi bonding: 

ic aromatic group include fused individual rings and include napthyl. Polycyclic aromatic groups include anthracenyl and phenanthrenyl and groups such as acenanaphthylenyl that contain fused rings of different sizes. If an aromatic group is selected, it is preferred that the group be fused to a heterocylic (saturated to particaly saturated ring include at least one hetero atom such as N, S or O) or heteroaromatic group. Exemplary heterocyclic or heteroaromatic groups include thiazoline, thizolidone, imidazole, imidazoline, thiazole, traizoles, tetrzole, thiadiazole, imidazole, pyridine and morpholine. The ligand includes a linking group that optionally comprises a sulfur ion. The monocyclic or polycylic group is substituted with a sulfate, sulfonate, phospahte, or phosphaonate group. These groups are sufficiently acidic to exist as charged moieites with a large pH range such as from 2-12. The monocylic or polycyclic group is tethtered to the solid support by a linking group which includes a mercapto, ether, or amino containing moeity. The solid support operated via “mixed modes” of interaction. The monocyclic and polycyclic groups have a pK below 4 and thus are negatively charged within the pH ranges used. A biological substance such as an immunoglobuilin, is contacted with the substrate between pH 4-6, in which the range the biological substance bears a net postive or neutral charge.. When the pH is raied above about 8, the biological substance gains a net negative charge, thereby creating an electrostati repulsion between the negatively charged solid substrate and the negativey charged biological substance. Consequently, the biological substance is released and can be isolated.