Ultra-stable protein ionic liquids

Inventors

Slocik, Joseph M • Naik, Rajesh R. • Dennis, Patrick B

Assignees

United States Department of the Air Force

Abstract

A method comprising: providing aqueous antibodies; cationizing the aqueous antibodies by the addition of stoichiometric amounts of an excess of a positively-charged crosslinker in the presence of a coupling reagent; titrating the cationized antibodies with a counter anionic polymer until the antibody cation/anion pair solution becomes negative by zeta potential measurement, to create at least one antibody cation/anion pair in aqueous solution. The antibodies are one of anti-hemoglobin antibodies, anti-horse spleen ferritin IgG antibodies, or blood-typing IgM Anti-A antibodies, single-chain antibodies from camelids, monoclonal Anti-Flag antibodies, monoclonal Anti-HRP2 to Plasmodium falciparum, polyclonal Anti-neuropeptide Y, and polyclonal Anti-human troponin. The antibody cation/anion pair solution may be lyophilized to remove all of the water, forming a lyophilized solid, and the lyophilized solid may be heated to generate an antibody ionic liquid.

Core Innovation

The invention provides ultra-stable, water-free biological materials, particularly antibody ionic liquids that are heat resistant and biologically active without needing refrigeration. The antibodies are chemically modified by cationizing aqueous antibodies through the addition of stoichiometric amounts of an excess positively-charged crosslinker in the presence of a coupling reagent, followed by titration with a counter anionic polymer until the solution becomes negative by zeta potential measurement, forming an antibody cation/anion pair solution in water. The water is then removed by lyophilization to create a solid which, upon heating, forms a stable antibody ionic liquid.

The problem addressed by the invention is that most biological materials, including proteins and antibodies, require aqueous environments and refrigeration to maintain stability and function, yet water promotes hydrolysis, oxidation, destabilization, and denaturation, leading to short shelf-lives and sensitivity to elevated temperatures. Current storage solutions involve refrigeration and freezing, but even then, water presence results in degradation. Additionally, many parts of the world lack refrigeration power resources. The invention overcomes these problems by removing most or all of the water without disrupting antibody structure, thereby increasing shelf-life, stability at elevated temperatures, and enabling refrigeration-free storage and handling.

The antibody ionic liquids maintain their biological recognition, specificity, and binding affinity comparable to native antibodies, despite chemical modification. The approach utilizes the physical properties of ionic liquids combined with antibody biological recognition to produce stable, heat-resistant liquids. Controlling the degree of cationization is critical to maintain antibody function while enabling ionic liquid formation. The invention exemplifies methods for selective modification of antibody acidic, amine, and hydroxyl groups with specific crosslinkers and coupling agents, followed by combination with biologically-compatible anionic polymers to form ionic salts that can be dried and heated to form ultra-stable ionic liquids.

Claims Coverage

The patent claims include one independent method claim for producing a stable antibody ionic liquid and one independent claim covering an ultra-stable ionic liquid composition comprising an antibody cation/anion pair. The following inventive features are extracted from these claims.

The claims cover a method for converting aqueous antibodies into stable antibody ionic liquids through controlled cationization, titration with a specific anionic polymer, removal of water by lyophilization, and heating to generate the ionic liquid. The claims also cover the ionic liquid compositions themselves, emphasizing stability, heat resistance, and maintained biological activity.

Stated Advantages

Documented Applications