Novel salts of dipicolinic acid as viscosity modifiers for high concentration antibody solutions.

Concentrated monoclonal antibody (mAb) solutions can lead to high viscosity as a result of protein-protein interactions and pose challenges for manufacture. Dipicolinic acid (DPA, pyridine-2,6-dicarboxylic acid) is a potential excipient for reduction of protein solution viscosity and here we describe new DPA salts with improved aqueous solubility. Crystallinity and solubility screens identified ethanolamine and diethanolamine as two promising counterions which generated crystalline, high melting point, anhydrous salt forms of DPA at 2:1 M stoichiometry.

Protein disorder-order interplay to guide the growth of hierarchical mineralized structures.

A major goal in materials science is to develop bioinspired functional materials based on the precise control of molecular building blocks across length scales. Here we report a protein-mediated mineralization process that takes advantage of disorder-order interplay using elastin-like recombinamers to program organic-inorganic interactions into hierarchically ordered mineralized structures. The materials comprise elongated apatite nanocrystals that are aligned and organized into microscopic prisms, which grow together into spherulite-like structures hundreds of micrometers in diameter that come together to fill macroscopic areas.

Dipicolinic acid as a novel spore-inspired excipient for antibody formulation.

Ionic excipients are commonly used in aqueous therapeutic monoclonal antibody (mAb) formulations. Novel excipients are of industrial interest, with a recent focus on Arg salt forms and their application as viscosity reducing and stabilizing additives. Here, we report that the calcium salt of dipicolinic acid (DPA, pyridine-2,6-dicarboxylic acid), uniquely present in nature in the core of certain bacterial spores, reduces the viscosity of a mAb formulated at 150mg/mL, below that achieved by Arg hydrochloride at the same concentration (10mM).

Mineralization and bone regeneration using a bioactive elastin-like recombinamer membrane.

The search for alternative therapies to improve bone regeneration continues to be a major challenge for the medical community. Here we report on the enhanced mineralization, osteogenesis, and in vivo bone regeneration properties of a bioactive elastin-like recombinamer (ELR) membrane. Three bioactive ELRs exhibiting epitopes designed to promote mesenchymal stem cell adhesion (RGDS), mineralization (DDDEEKFLRRIGRFG), and both cell adhesion and mineralization were synthesized using standard recombinant protein techniques.

Bioactive membranes for bone regeneration applications: effect of physical and biomolecular signals on mesenchymal stem cell behavior.

This study focuses on the in vitro characterization of bioactive elastin-like recombinamer (ELR) membranes for bone regeneration applications. Four bioactive ELRs exhibiting epitopes designed to promote mesenchymal stem cell adhesion (RGDS), endothelial cell adhesion (REDV), mineralization (HAP), and both cell adhesion and mineralization (HAP-RGDS) were synthesized using standard recombinant protein techniques. The materials were then used to fabricate ELR membranes incorporating a variety of topographical micropatterns including channels, holes and posts.

Design of biomolecules for nanoengineered biomaterials for regenerative medicine.

An important goal in the development of highly functional organic materials is to design self-assembling molecules that can reproducibly display chemical signals across length scales. Within the biomedical field, biomolecules are highly attractive candidates to serve as bioactive building blocks for the next generation of biomaterials. The peptide amphiphiles (PAs) developed by the Stupp Laboratory at Northwestern University generated a highly versatile self-assembly code to create well-defined bioactive nanofibers that have been proven to be very effective at signaling cells in vitro and in vivo.

Engineering membrane scaffolds with both physical and biomolecular signaling.

We report on the combination of a top-down and bottom-up approach to develop thin bioactive membrane scaffolds based on functional elastin-like polymers (ELPs). Our strategy combines ELP cross-linking and assembly, and a variety of standard and novel micro/nanofabrication techniques to create self-supporting membranes down to ∼500 nm thick that incorporate both physical and biomolecular signals, which can be easily tailored for a specific application. In this study we used an ELP that included the cell-binding motif arginine-glycine-aspartic acid-serine (RGDS).

Integrating top-down and self-assembly in the fabrication of peptide and protein-based biomedical materials.

The capacity to create an increasing variety of bioactive molecules that are designed to assemble in specific configurations has opened up tremendous possibilities in the design of materials with an unprecedented level of control and functionality. A particular challenge involves guiding such self-assembling interactions across scales, thus precisely positioning individual molecules within well-organized, highly-ordered structures. Such hierarchical control is essential if peptides and proteins are to serve as both structural and functional building blocks of biomedical materials.