In-situ biophysical characterization of high-concentration protein formulations using wNMR.

High-concentration protein formulation is of paramount importance in patient-centric drug product development, but it also presents challenges due to the potential for enhanced aggregation and increased viscosity. The analysis of critical quality attributes often necessitates the transfer of samples from their primary containers together with sample dilution. Therefore, there is a demand for noninvasive, in situ biophysical methods to assess protein drug products directly in primary sterile containers, such as prefilled syringes, without dilution. In this study, we introduce a novel application of water proton nuclear magnetic resonance (wNMR) to evaluate the aggregation propensity of a high-concentration drug product, Dupixent® (dupilumab), under stress conditions. wNMR results demonstrate a concentration-dependent, reversible association of dupilumab in the commercial formulation, as well as irreversible aggregation when exposed to accelerated thermal stress, but gradually reversible aggregation when exposed to freeze and thaw cycles. Importantly, these results show a strong correlation with data obtained from established biophysical analytical tools widely used in the pharmaceutical industry. The application of wNMR represents a promising approach for in situ noninvasive analysis of high-concentration protein formulations directly in their primary containers, providing valuable insights for drug development and quality assessment.

Analysis of the Adsorbed Vaccine Formulations Using Water Proton Nuclear Magnetic Resonance-Comparison with Optical Analytics.

PURPOSE: To evaluate wNMR, an emerging noninvasive analytical technology, for characterizing aluminum-adjuvanted vaccine formulations. METHODS: wNMR stands for water proton nuclear magnetic resonance. In this work, wNMR and optical techniques (laser diffraction and laser scattering) were used to characterize vaccine formulations containing different antigen loads adsorbed onto AlPO4 adjuvant microparticles, including the fully dispersed state and the sedimentation process. All wNMR measurements were done noninvasively on sealed vials containing the adsorbed vaccine suspensions, while the optical techniques require transferring the adsorbed vaccine suspensions out of the original vial into specialized cuvette/tube for analysis. For analyzing fully dispersed suspensions, optical techniques also require sample dilution. RESULTS: wNMR outperformed laser diffraction in differentiating high- and low-dose formulations of the same vaccine, while wNMR and laser scattering achieved comparable results on vaccine sedimentation kinetics and the compactness of fully settled vaccines. CONCLUSION: wNMR could be used to analyze aluminum-adjuvanted formulations and to differentiate between formulations containing different antigen loads adsorbed onto aluminum adjuvant microparticles. The results demonstrate the capability of wNMR to characterize antigen-adjuvant complexes and to noninvasively inspect finished vaccine products.

Sedimentation behavior of quality and freeze-damaged aluminum-adjuvanted vaccines by wNMR.

Vaccine sedimentation and resuspension are properties that vaccine makers use to characterize a suspension product during research and development as well as throughout the shelf life of the vaccine. Three vaccines with three different aluminum adjuvants and different antigens were selected and monitored over the course of sedimentation using water proton nuclear magnetic resonance (wNMR) relaxometry. This simple method measured fully intact, single-dose vaccine vials and reported sedimentation profiles for each, which readily distinguished freeze-stressed vaccines from unstressed vaccines.

Supramolecular Protein-Polyelectrolyte Assembly at Near Physiological Conditions-Water Proton NMR, ITC, and DLS Study.

The in vivo potency of polyphosphazene immunoadjuvants is inherently linked to the ability of these ionic macromolecules to assemble with antigenic proteins in aqueous solutions and form physiologically stable supramolecular complexes. Therefore, in-depth knowledge of interactions in this biologically relevant system is a prerequisite for a better understanding of mechanism of immunoadjuvant activity. Present study explores a self-assembly of polyphosphazene immunoadjuvant-PCPP and a model antigen-lysozyme in a physiologically relevant environment-saline solution and neutral pH. Three analytical techniques were employed to characterize reaction thermodynamics, water-solute structural organization, and supramolecular dimensions: isothermal titration calorimetry (ITC), water proton nuclear magnetic resonance (wNMR), and dynamic light scattering (DLS). The formation of lysozyme-PCPP complexes at near physiological conditions was detected by all methods and the avidity was modulated by a physical state and dimensions of the assemblies. Thermodynamic analysis revealed the dissociation constant in micromolar range and the dominance of enthalpy factor in interactions, which is in line with previously suggested model of protein charge anisotropy and small persistence length of the polymer favoring the formation of high affinity complexes. The paper reports advantageous use of wNMR method for studying protein-polymer interactions, especially for low protein-load complexes.

Quality assurance at the point-of-care: Noninvasively detecting vaccine freezing variability using water proton NMR.

Aluminum-adjuvanted vaccines are freeze-sensitive products that require attentive cold chain adherence. Freeze/thaw events can be tested using "The World Health Organization Shake Test", a qualitative test whereby a vial from the batch suspected to have been frozen is checked to infer whether the whole batch has been frozen. In this paper, we present a noninvasive and quantitative method to detect whether a vial of liquid vaccine has experienced freeze/thaw using the water proton transverse relaxation rate by Nuclear Magnetic Resonance relaxometry (wNMR relaxometry). Importantly, wNMR relaxometry does not compromise the vial's integrity so the analyzed vial can be used for vaccination if it meets the quality specifications. Vial-to-vial variability in freezing susceptibility within a single carton of vaccine vials was also detected, both by visual observation and concurrently by wNMR relaxometry. This variability brings into question the practice of using one or a few vials in a batch of vaccines to infer about the quality of the whole batch.

Flow Water Proton NMR: In-Line Process Analytical Technology for Continuous Biomanufacturing.

Continuous manufacturing of biologics is one of the priorities of the biopharmaceutical industry. However, its widespread implementation is hampered by a lack of noninvasive/nondestructive process analytical technology (PAT) systems capable of real-time in-line monitoring of product flow parameters, such as concentration and/or aggregate content. We have previously demonstrated that, under nonflow conditions, the water proton transverse relaxation rate, R2(1H2O), is sensitive to protein concentration and aggregate content in biopharmaceutical formulations. In the present work, we explored the potential of water proton NMR under flow conditions (flow-wNMR) to use R2(1H2O) as a quantitative indicator of protein concentration variations and aggregate levels in the process flow. We show that, under flow conditions, R2(1H2O) is sensitive to rather small changes in protein concentration (<1 mg/mL) and is capable to detect variations in the aggregate content of <1%. Our findings suggest that flow-wNMR could be advantageously used as a real-time in-line noninvasive PAT for continuous biomanufacturing.

Correction to: Nondestructive Quantitative Inspection of Drug Products Using Benchtop NMR Relaxometry-the Case of NovoMix® 30.

Typesetting error occurred and author corrections to the equations and text edits at the proofing stage were not incorporated in the published article. The original article has been corrected.

Nondestructive Quantitative Inspection of Drug Products Using Benchtop NMR Relaxometry-the Case of NovoMix® 30.

Batch-level inference-based quality control is the standard practice for drug products. However, rare drug product defects may be missed by batch-level statistical sampling, where a subset of vials in a batch is tested quantitatively but destructively. In 2013, a suspension insulin product, NovoLog® Mix 70/30 was recalled due to a manufacturing error, which resulted in insulin strength deviations up to 50% from the labeled value. This study analyzed currently marketed FlexPen® devices by the water proton transverse relaxation rate using a benchtop nuclear magnetic resonance relaxometer. The water proton transverse relaxation rate was found to be sensitive to detecting concentration changes of the FlexPen® product. These findings support the development of vial-level verification-based quality control for drug products where every vial in a batch is inspected quantitatively but nondestructively.

Use of Water Proton NMR to Characterize Protein Aggregates: Gauging the Response and Sensitivity.

Water proton transverse relaxation rate R2(1H2O) measurements by NMR stand out as a powerful noninvasive tool to detect protein aggregates, including subvisible particles in biopharmaceutical formulations. To understand the applicability of water proton NMR ( wNMR), we studied the response and sensitivity of wNMR to the aggregates of a monoclonal antibody (mAb) within a wide size range at different aggregate levels, for three different physical stresses: freeze-thaw cycling, heating, and agitation. We compared the sensitivity and response of wNMR with those observed by conventional techniques of size exclusion chromatography (SEC), microflow imaging (MFI), and dynamic light scattering (DLS). Our findings showed that wNMR detects mAb aggregates within wide aggregate levels and in a wide range of aggregate sizes. wNMR was sensitive to an increase in soluble protein aggregates in the range of <1.0%. In most cases, wNMR demonstrated linear response toward the aggregate fraction. Nonlinearity of such response potentially points to the presence of larger size aggregates that possibly rearrange and/or dissociate upon dilution. The results demonstrate the potential of wNMR as a quantitative and noninvasive analytical tool for characterizing protein aggregates in biopharmaceutical formulations.

Water proton NMR detection of amide hydrolysis and diglycine dimerization.

The transverse relaxation rate of water protons R2(1H2O) is found to be sensitive to amide hydrolysis and diglycine dimerization. The results demonstrate the feasibility of using R2(1H2O) as a diagnostic tool to detect chemical changes in aqueous solutions. Potential applications include drug product formulation and inspection.

Water Proton NMR: A Tool for Protein Aggregation Characterization.

Formulation stability is a critical attribute of any protein-based biopharmaceutical drug due to a protein's 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.

Using Small-Angle Scattering Techniques to Understand Mechanical Properties of Biopolymer-Based Biomaterials.

The design and engineering of innovative biopolymer-based biomaterials for a variety of biomedical applications should be based on the understanding of the relationship between their nanoscale structure and mechanical properties. Down the road, such understanding could be fundamental to tune the properties of engineered tissues, extracellular matrices for cell delivery and proliferation/differentiation, etc. In this tutorial review, we attempt to show in what way biomaterial structural data can help to understand the bulk material properties. We begin with some background on common types of biopolymers used in biomaterials research, discuss some typical mechanical testing techniques and then review how others in the field of biomaterials have utilized small-angle scattering for material characterization. Detailed examples are then used to show the full range of possible characterization techniques available for biopolymer-based biomaterials. Future developments in the area of material characterization by small-angle scattering will undoubtedly facilitate the use of structural data to control the kinetics of assembly and final properties of prospective biomaterials.

Split of chiral degeneracy in mechanical and structural properties of oligopeptide-polysaccharide biomaterials.

Enantiomeric biomaterials which are mirror images of each other are characterized by chiral degeneracy--identical structural characteristics and bulk material properties. The addition of another chiral component, D-polysaccharide, has been shown to split such degeneracy and result in two distinct biomaterials. Dynamic oscillatory rheometry and small-angle X-ray scattering demonstrate that the natural biochirality combination of L-peptides and D-polysaccharides assembles faster, has higher elastic moduli (G'), and is structurally more beneficial as opposed to the alternative D-peptide and D-polysaccharide combination. Chemical modifications of the OH-groups in α-D-glucose units in D-polysaccharides weaken such splitting of chiral degeneracy. These findings form a basis to design novel biomaterials and provide additional insight on why proteins and polysaccharides have oppoiste chirality in the biological world.

An interplay between electrostatic and polar interactions in peptide hydrogels.

Inherent chemical programmability available in peptide-based hydrogels has allowed diversity in the development of these materials for use in biomedical applications. Within the 20 natural amino acids, a range of chemical moieties are present. Here we used a mixing-induced self-assembly of two oppositely charged peptide modules to form a peptide-based hydrogel. To investigate electrostatic and polar interactions in the hydrogel, we replace amino acids from the negatively charged acidic glutamic acid (E) to the uncharged polar glutamine (Q) on a negatively charged peptide module, while leaving the positively charged module unchanged. Using dynamic rheology, the mechanical properties of each hydrogel were investigated. It was found that the number, but not the location, of electrostatic interactions (E residues) dictate the elastic modulus (G') of the hydrogel, compared to polar interactions (Q residues). Increased electrostatic interactions also promote faster peptide assembly into the hydrogel matrix, and result in the decrease of T2 relaxation times of H2 O and trifluoroacetic acid. Small-angle X-ray scattering (SAXS) showed that changing from electrostatic to polar interactions affects the ability to form fibrous networks: from the formation of elongated fibers to no fiber assembly. This study reveals the systematic effects that the incorporation of electrostatic and polar interactions have when programmed into peptide-based hydrogel systems. These effects could be used to design peptide-based biomaterials with predetermined properties.

Enhancing biocompatibility of D-oligopeptide hydrogels by negative charges.

Oligopeptide hydrogels are emerging as useful matrices for cell culture with commercial products on the market, but L-oligopeptides are labile to proteases. An obvious solution is to create D-oligopeptide hydrogels, which lack enzymatic recognition. However, D-oligopeptide matrices do not support cell growth as well as L-oligopeptide matrices. In addition to chiral interactions, many cellular activities are strongly governed by charge-charge interactions. In this work, the effects of chirality and charge on human mesenchymal stem cell (hMSC) behavior were studied using hydrogels assembled from oppositely charged oligopeptides. It was found that negative charges significantly improved hMSC viability and proliferation in D-oligopeptide gels but had little effect on their interactions with L-oligopeptide gels. This result points to the possibility of using charge and other factors to engineer biomaterials whose chirality is distinct from that of natural biomaterials, but whose performance is close to that of natural biomaterials.

The Effect of Ionic Strength on the Mechanical, Structural and Transport Properties of Peptide Hydrogels.

It is found that the elastic modulus of a peptide hydrogel increases linearly with the logarithm of its ionic strength. This result indicates that the elastic modulus of this class of hydrogels can be tuned by the ionic strength in a highly predictable manner. Small-angle X-ray scattering studies reveal that higher ionic strength leads to thinner but more rigid peptide fibers that are packed more densely. The self-diffusion coefficient of small molecules inside the hydrogel decrease linearly with its ionic strength, but this decrease is mainly a salt effect rather than diffusion barriers imposed by the hydrogel matrix.

Viscoelastic properties and nanoscale structures of composite oligopeptide-polysaccharide hydrogels.

Biocompatible and biodegradable peptide hydrogels are drawing increasing attention as prospective materials for human soft tissue repair and replacement. To improve the rather unfavorable mechanical properties of our pure peptide hydrogels, in this work we examined the possibility of creating a double hydrogel network. This network was created by means of the coassembly of mutually attractive, but self-repulsive oligopeptides within an already-existing fibrous network formed by the charged, biocompatible polysaccharides chitosan, alginate, and chondroitin. Using dynamic oscillatory rheology experiments, it was found that the coassembly of the peptides within the existing polysaccharide network resulted in a less stiff material as compared to the pure peptide networks (the elastic modulus G' decreased from 90 to 10 kPa). However, these composite oligopeptide-polysaccharide hydrogels were characterized by a greater resistance to deformation (the yield strain γ grew from 4 to 100%). Small-angle neutron scattering (SANS) was used to study the 2D cross-sectional shapes of the fibers, their dimensional characteristics, and the mesh sizes of the fibrous networks. Differences in material structures found with SANS experiments confirmed rheology data, showing that incorporation of the peptides dramatically changed the morphology of the polysaccharide network. The resulting fibers were structurally very similar to those forming the pure peptide networks, but formed less stiff gels because of their markedly greater mesh sizes. Together, these findings suggest an approach for the development of highly deformation-resistant biomaterials.

Chirality-Mediated Mechanical and Structural Properties of Oligopeptide Hydrogels.

The origin and the effects of homochirality in the biological world continuously stimulate numerous hypotheses and much debate. This work attempts to look at the biohomochirality issue from a different angle-the mechanical properties of the bulk biomaterial and their relation to nanoscale structures. Using a pair of oppositely charged peptides that co-assemble into hydrogels, we systematically investigated the effect of chirality on the mechanical properties of these hydrogels through different combinations of syndiotactic and isotactic peptides. It was found that homochirality confers mechanical advantage, resulting in higher elastic modulus and strain yield value. Yet, heterochirality confer kinetic advantage, resulting in faster gelation. Structurally, both homochiral and heterochiral hydrogels are made of fibers interconnected by lappet-like webs, but the homochiral peptide fibers are thicker and denser. The result highlights the possible role of biohomochirality in the evolution and/or natural selection of biomaterials.

Diffusion of small molecules inside a peptide hydrogel.

A set of four phenylalanine analogues experiences diffusion retardation when transferred from phosphate-buffered saline into a peptide hydrogel of the same pH and ionic strength. The extent of retardation increases linearly with logP(oct), their lipophilicity.

Linear Dependency of NMR Relaxation Rates on Shear Modulus in Hydrogels.

It is found that the NMR relaxation rates of diffusants in peptide hydrogels have a linear dependency on the shear modulus of the hydrogels. This finding opens the door for non-invasive and forceless mechanical characterizations of materials and tissues using NMR and MRI.