Effects of Ice-binding Proteins from Cold-adapted Insect Tenebrio Molitor on Calcite Crystallization

Undergraduate #150
Discipline: Chemistry and Chemical Sciences
Subcategory: Biochemistry (not Cell and Molecular Biology and Genetics)

Audrey Kishishita - California State University, Los Angeles (CSULA)
Co-Author(s): JJoshua Lugo and Xin Wen, Department of Chemistry and Biochemistry, California State University, Los Angeles

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The formation of sparingly soluble and insoluble inorganic salts (i.e., scale deposits) is a major problem an industrial and domestic setting. To control scale deposits, chemical scale inhibitors are commonly used. Commercial antiscaling agents include polyelectrolytes that dissociate phosphonates, carboxylates, and sulfonates anionic groups. However, it is imperative to identify highly efficient polymeric inhibitors and environmentally friendly antiscalants, in particular, to replace phosphonate inhibitors due to their environmental risks. Ice-binding proteins or antifreeze proteins (AFPs) from cold-adapted organisms (e.g., fish, insects, and plants) can bind to specific ice surfaces, thereby inhibiting the nucleation and crystallization of ice. AFPs cam also control the crystallization of some non-ice like compounds by interacting with the crystalline surfaces of these compounds. We correlate the charge and molecular properties of the polyelectrolytes with their efficiencies in inhibiting the scale crystal formation. A beetle AFP from Tenebrio molitor (TmAFP) having regular spaced charged residues on its surfaces is prepared and studied here. Calcium carbonate (CaCO3), a common scale deposit, is a scalent of interest in this study. We investigate the effects of TmAFP on the formation of CaCO3. Our results show that the presence of TmAFP inhibits the formation of CaCO3 resulting much fewer CaCO3 crystals. The achieved CaCO3 crystals in the absence and presence of TmAFP are both characterized to be calcite using Fourier transform infrared (FTIR) spectroscopy. The results suggest that the presence of TmAFP does not change the polymorph of CaCO3. By analyzing the charged residues on the surfaces of TmAFP and calcite surfaces, we propose that TmAFP may affect the formation of calcite via adsorption to the crystalline surfaces of CaCO3. This study provides better understanding for scale control as well as new designs for green antiscalants.

Funder Acknowledgement(s): Minority Biomedical Research Support-Research Initiative for Scientific Enhancement (MBRS-RISE); Minority Access to Research Careers-Undergraduate Student Training for Academic Research (MARC-U*STAR).

Faculty Advisor: Xin Wen, xwen3@calstatela.edu

Role: Sample preparation, data collection, and device calibration was done by me. Some data was collected using an outside facility, where I prepared the sample and sent it to an outside facility.