Protein-Polyelectrolyte Complexes and Micellar Assemblies.

In this review, we highlight the recent progress in our understanding of the structure, properties and applications of protein-polyelectrolyte complexes in both bulk and micellar assemblies. Protein-polyelectrolyte complexes form the basis of the genetic code, enable facile protein purification, and have emerged as enterprising candidates for simulating protocellular environments and as efficient enzymatic bioreactors. Such complexes undergo self-assembly in bulk due to a combined influence of electrostatic interactions and entropy gains from counterion release. Diversifying the self-assembly by incorporation of block polyelectrolytes has further enabled fabrication of protein-polyelectrolyte complex micelles that are multifunctional carriers for therapeutic targeted delivery of proteins such as enzymes and antibodies. We discuss research efforts focused on the structure, properties and applications of protein-polyelectrolyte complexes in both bulk and micellar assemblies, along with the influences of amphoteric nature of proteins accompanying patchy distribution of charges leading to unique phenomena including multiple complexation windows and complexation on the wrong side of the isoelectric point

Self-Assembly of Functional Polyelectrolyte-Nanoparticle Materials

This dissertation delineates my research on the electrostatically driven self-assembly on a wide range of materials. These materials include zeolites where metal cations act as structure directing agents, polyelectrolyte nanoparticle complexes with tunable interparticle separation, stabilized polyelectrolyte complex coacervate microdroplet dispersions and complex coacervate protocells with encapsulated enzymes to model biomolecular condensates. In all these systems, coulombic interactions play a central role in governing the functionality of the resultant material in distinct ways. For zeolites, the valency of the metal cation influences their micropore topology and the co-precipitation of different structures can be accomplished by tuning the cation content. In the case of polyelectrolyte-nanoparticle systems, the charge ratio of these two components directs the average interparticle distance in the complex which can be effectively manipulated. The coacervate microdroplet dispersions were studied in high throughput, and the addition of comb-polyelectrolytes suppress their coalescence and provide long-term stability against high ionic screening. Enzymes spontaneously partition into these coacervate domains due to their heterogenous surface charge, and such stabilized coacervate microdroplets can serve as in vitro protocells models and can elucidate the reaction-diffusion kinetics of enzymatic reactions

Protein–Polyelectrolyte Complexes and Micellar Assemblies

In this review, we highlight the recent progress in our understanding of the structure, properties and applications of protein–polyelectrolyte complexes in both bulk and micellar assemblies. Protein–polyelectrolyte complexes form the basis of the genetic code, enable facile protein purification, and have emerged as enterprising candidates for simulating protocellular environments and as efficient enzymatic bioreactors. Such complexes undergo self-assembly in bulk due to a combined influence of electrostatic interactions and entropy gains from counterion release. Diversifying the self-assembly by incorporation of block polyelectrolytes has further enabled fabrication of protein–polyelectrolyte complex micelles that are multifunctional carriers for therapeutic targeted delivery of proteins such as enzymes and antibodies. We discuss research efforts focused on the structure, properties and applications of protein–polyelectrolyte complexes in both bulk and micellar assemblies, along with the influences of amphoteric nature of proteins accompanying patchy distribution of charges leading to unique phenomena including multiple complexation windows and complexation on the wrong side of the isoelectric point

Metal Cations as Inorganic Structure-Directing Agents during the Synthesis of Phillipsite and Tobermorite

The Structure of Porous Materials in the Absence of Organic Structure-Directing Agents Highlights the Adaptable Nature of Metal Cations during Hydrothermal Synthesis. Here, We Perform Template-Free Hydrothermal Treatments to Synthesize Phillipsite and Tobermorite, at the Same Molar Precursor Ratios, While Varying the Identity and Compositions of the Counterbalancing Metal Cations that Act as Inorganic Structure-Directing Agents. Phillipsite is Crystallized Selectively at Low Total Cationic Charges (In the Recovered Solids) in the Presence of Sodium and Potassium at 373 and 393 K. Partial Substitution of Sodium and Potassium with Calcium in the Synthesis Gels Results in the Co-Precipitation of Tobermorite Phases in Proportion to the Calcium Substitution Amount. Exclusive Tobermorite Precipitation Was Observed from Synthesis Growth Solutions Containing Only Calcium (373 and 393 K). X-Ray Diffraction (XRD) Patterns, Together with Nitrogen Adsorption Isotherms (At 77 K), Indicate a Monotonic Increase in the Fraction of Tobermorite Crystals with Increasing Calcium Content in Synthesis Gels. Differences in Framework Topology, Dictated by the Choice of Metal Cation, Are Accentuated by the Quantity of Metal Cation Retention within the Available and Interfacial Cavities of Phillipsite ((K + Na + Ca)/Al ≤ 1) and Tobermorite ((K + Na + Ca)/Al ≥ 1). These Results Demonstrate the Important Role of Metal Cations during Crystallization Processes and their Ability to Vary Framework Topology in Porous Materials