Poster C8 - Investigating Effects of pH and Salt on Protein Coacervation Systems and Polymer Complexes

Friday, October 25, 2024

10:00 AM - 11:00 AM EST

Location: Exhibit Hall E, F & G

Presenting Author(s)

Margaret Campbell

Undergraduate Research Assistant in Chemical Engineering at Lehigh University
Lehigh University
Bethlehem, Pennsylvania, United States

Co-Author(s)

Chaeyoung Lim, MEng

PhD Student in the Department of Chemical and Biomolecular Engineering at Lehigh University
Lehigh University, United States

Primary Investigator(s)

Whitney Blocher McTigue, PhD (she/her/hers)

Assistant Professor in the Department of Chemical and Biomolecular Engineering at Lehigh University
Lehigh University, United States

Introduction: To enhance the human experience and develop more organic, environmentally-conscious materials for efficient and functional use, the fields of heteroprotein and polymer coacervation have been gaining traction in the scientific community. When investigating the uses of these complex coacervates in real-world applications, two of the most vital variables to be closely monitored include pH and salt concentration, specifically the effects of each factor on forming, maintaining, and degrading the desired phase. Phase diagrams have been formulated and utilized to further examine these crucial factors’ effects and take out each system’s guesswork.

Materials and

Methods: Complex heteroprotein coacervation employs electrostatic relationships between proteins to construct polyelectrolyte complexes. Various relationships were investigated, involving a combination of two proteins per system. These proteins included Beta Lactoglobulin (BLG), Lactoferrin (LF), Bovine Serum Albumin (BSA), Hen Egg White Lysozyme (HEWL), Gelatin A (GelA), and Gelatin B (GelB). When examining relationships between various polymers, Poly(diallyldimethylammonium chloride) (PDADMAC), Carboxymethyl Cellulose (CMC), and Poly(L-Lysine) (PLK) were used, and their relationships examined two-at-a-time, similarly to the protein systems. Sodium chloride (NaCl) was the primary salt used. For evaluation and verification of phase, both microscopy and turbidimetry were utilized. In some larger-scale experiments investigating the effects of salt addition order, a centrifuge and T-test were used for data comparison purposes.

Results, Conclusions, and Discussions: As these experiments essentially involved creating a data-base of information on each protein relationship, various results were obtained for each system. Using microscopy and turbidity, phase diagrams were built for each system and cross-examined. In general, protein systems combined with salt showed volatile results. Without salt, most protein systems showed consistent results at specific ideal pH values. When it came to exploring the effects of salt order in forming and maintaining various phases, adding salt last to each system raised average turbidity values, although because of the high variability involved, attempts to quantify these systems on a larger scale were abandoned, but may be eventually returned to. Phase diagrams were created for the other various polymer systems and general trends observed.
With the results obtained from our experiments, we have added to the database of knowledge on heteroprotein and polymer systems, specifically when investigating the effects of varying charge fractions, salt concentrations, pH, and order of salt addition. This information is vital in ensuring the proper development of heteroprotein coacervates and is essential to thorough research, particularly regarding the formation, maintenance, and degradation of the coacervate phase. The work and results tailor our future discussion of product development and sustainability in heteroprotein and polymer chemistry.

Acknowledgements (Optional):