(340af) High-Throughput Passive Microrheological Screening of Gelation Conditions of Protein Hydrogels

Passive microrheology techniques such as multiple particle tracking (MPT) and differential dynamic microscopy (DDM) are effective methods for rapidly screening a library of materials or conditions. In protein-based materials research, use of these techniques can be advantageous to circumvent the grueling preparation of large quantities of sample and instead screen volumes on the order of tens of microliters. We’ve previously characterized the pentameric coiled-coil protein, Q, for its upper critical solution temperature (UCST) phase behavior across different pH levels, showing higher elastic moduli near its isoelectric point. These studies were extended further, using passive microrheology techniques to track the self-assembly and gelation of Q across different combinations of environmental conditions by varying pH levels and ionic strengths. The protein was confirmed to undergo faster gelation near its isoelectric point as well as at higher ionic strengths within the range studied. Additionally, MPT and DDM showed distinct advantages when compared to each other; MPT yielded information on the homogeneity of the phase transition via individual bead trajectories, while the lower computational cost of DDM allowed for high-throughput data processing. Coupled with computational modeling of the protein at the different conditions, these results provide insights into the driving factors of the self-assembly mechanism of coiled-coil proteins and suggest that electrostatic interactions play a key role.

Research Interests

The ability of biomaterials to be imbued with sensitivity to external triggers makes them attractive candidates for biomedical applications. My research interests lie in understanding the self-assembly of protein biomaterials in response to changing environmental conditions and external stimuli. These overlap with many industrial interests, specifically the development of new therapeutic modalities that utilize different stimuli to trigger release of drug products. By joining industry, I aim to broaden my knowledge of self-assembling biomaterials and how they can be optimized for use in therapeutics delivery.

Research Experience

Throughout my graduate studies, my research has focused on elucidating key factors that drive the self-assembly of a coiled-coil protein, Q, which is derived from the coiled-coil domain of cartilage oligomeric matrix protein. The effects of temperature on protein phase behavior has been widely reported on, particularly the lower critical solution temperature phase behavior that is exhibited by proteins such as elastin-like polypeptides; however, our work reports the first upper critical solution temperature (UCST) protein hydrogel that is based on a single coiled-coil protein. While UCST hydrogels are not traditionally used in biomedical applications because of their solution-to-gel (sol-gel) transition occurring at low temperatures, Q has shown promise in biomedical applications including drug delivery due to its ability to be stabilized at physiological temperature upon binding with the small hydrophobic molecule, curcumin.

The UCST phase behavior previously described is driven by electrostatic interactions between surface-exposed residues of the pentamer. To this end, it is critical to screen a multitude of environmental conditions (pH and ionic strength) in order to delineate the driving factors for self-assembly. Our work suggests that the minimization of electrostatic repulsions near the isoelectric point is believed to allow coiled-coils to self-assembly and eventually form a hydrogel via physical crosslinking of fibers. The information gained during from these studies can inform the design of new variants with varying surface charge representations. Due to the ever-evolving landscape of proteins and biomaterials, the development of design-build-test cycles such as the aforementioned one are crucial to developing novel materials.