Marc B. Taraban

Water Proton NMR for In Situ Detection of Insulin Aggregates

The need for quality control during the manufacturing and distribution of biopharmaceuticals is becoming increasingly necessary. At present, detecting drug degradation through the monitoring of active factor aggregation is accomplished through invasive techniques, such as size-exclusion chromatography (SEC), analytical ultracentrifugation (AUC), and so on. Unfortunately, these analytical methods require sampling the drug by opening the drug container that renders the remaining drug unusable regardless of the outcome of the test. Visual inspection, the current non-invasive quality control method is qualitative and can only detect visible particulates. Thus, it will miss sub-visible protein aggregates. In this paper, human insulin preparations were used to demonstrate that the transverse relaxation rate of water protons R2 ((1) H2 O) can serve as a sensitive and reliable indicator to detect and quantify both visible and sub-visible protein aggregates. R2 ((1) H2 O) is measured using a wide-bore low-field bench-top NMR instrument with permanent magnets. Such analysis could be carried out without opening the drug container, thus saving a drug for further use. The results suggest a novel, economical, non-destructive in situ analytical technique that allows for on-the-site quantification of protein aggregation in biopharmaceutical products.

Water Proton NMR: A Tool for Protein Aggregation Characterization

Formulation stability is a critical attribute of any protein-based biopharmaceutical drug due to a proteins inherent tendency to aggregate. Advanced analytical techniques currently used for characterization of protein aggregates are prone to a number of limitations and usually require additional manipulations with the sample, such as dilution, separation, labeling, and use of special cuvettes. In the present work, we compared conventional techniques for the analysis of protein aggregates with a novel approach that employs the water proton transverse relaxation rate R2(1H2O). We explored differences in the sensitivity of conventional techniques, size-exclusion chromatography (SEC), microflow imaging (MFI), and dynamic light scattering (DLS), and water NMR (wNMR) toward the presence of monoclonal antibody aggregates generated by different stresses. We demonstrate that wNMR outperformed SEC, DLS, and MFI in that it was most consistently sensitive to increases in both soluble and insoluble aggregates, including subvisible particles. The simplicity of wNMR, its sensitivity, and possibility of noninvasive measurements are unique advantages that would permit its application for more efficient and higher throughput optimization of protein formulations.

Conformational transition of a non-associative fluorinated amphiphile in aqueous solution

Amphiphiles comprise a hydrophobic moiety and a hydrophilic moiety. A common property of many amphiphiles is to self-associate in aqueous solutions, driven by the need to shield the hydrophobic moiety from water. This feature has been utilized extensively to create various nano-scale architectures from amphiphiles. However, to effectively control amphiphile behavior, one should have the ability to both promote and prevent self-association. Fluorinated amphiphiles are especially prone to self-association, thus presenting a big challenge in developing non-associative amphiphiles. In this work, we solve this challenge by creating steric hindrance to association. The resulting fluorinated asymmetric amphiphile remains monomeric well above its apparent critical micelle concentration and up to its solubility limit, as demonstrated by small-angle X-ray and neutron scattering, dynamic light scattering and NMR diffusometry techniques. Not being able to associate intermolecularly, the amphiphile undergoes an intramolecular conformational transition, akin to protein folding, to wrap its hydrophilic moiety around its hydrophobic fluorocarbon moiety to shield it from water. This work demonstrates that steric hindrance is an effective tool in creating non-associative amphiphiles.

Improving Biopharmaceutical Safety through Verification-Based Quality Control

Biopharmaceuticals and small-molecule drugs have different approval pathways but the same quality control (QC) paradigm, where the quality of released but untested units is inferred from that of tested but destroyed units. This inference-based QC will likely miss rare prerelease defects, and defects emerging after product release. The likelihood for such defects is heightened for biopharmaceuticals due to their complexity, which makes manufacturing errors more likely, and fragility, which makes postrelease damage more likely. To improve biopharmaceutical safety, we suggest transitioning their QC from inference- to verification-based practice by developing inspection technologies that can nondestructively verify the quality of every vial from the point of release to the point of care. One candidate, water proton NMR (wNMR), is briefly discussed.

Correction: Conformational transition of a non-associative fluorinated amphiphile in aqueous solution

Correction for ‘Conformational transition of a non-associative fluorinated amphiphile in aqueous solution’ by Marc B. Taraban et al., RSC Adv., 2014, 4, 54565–54575.

Linear Dependence of Water Proton Transverse Relaxation Rate on Shear Modulus in Hydrogels

It is found that hydrogelation of peptides enhances the transverse relaxation rate R2 of water protons but has no effect on the longitudinal relaxation rate R1 and the diffusion coefficient D. The magnitude of water proton R2 enhancement increases linearly with the shear modulus G of hydrogels.