Session: 16-01-01: Government Agency Student Poster Competition

Paper Number: 150591

150591 - Modulation of Controlled Protein Release From Alginate Hydrogel via Electrochemically Generated Local Ph Changes 

Smart release systems have been extensively studied over the past few decades, proving particularly significant for biomedical and drug delivery applications. This approach allows to undergo fewer treatment procedures and improves therapeutic efficacy while lowering systemic toxicity. Payload release can be controlled by variety of stimuli, such as pH, which will allow the biomolecules to be released or stay retained within the carrier based on both system conditions and biomolecule parameters.

The first studied release system, which was based on electrochemically deposited alginate hydrogel, is pH-dependent due to the weakly acidic nature of the material. Controlled pulsatile protein release was achieved using electrochemically induced cyclic pH changes via redox reactions of ascorbate oxidation (acidification, resulting in decreasing pH locally near an electrode surface) or oxygen reduction (basification, resulting in increasing pH locally near an electrode surface) that happen due to an applied electric potential of +0.6 V and -0.8 V vs Ag/AgCl/KCl, respectively. The obtained local acidic solution resulted in protonation of carboxylic groups in the alginate hydrogel and as the result formation of a hydrophobic shrunk hydrogel film. Conversely, the produced alkaline local environment resulted in a hydrophilic swollen hydrogel film. The release of the proteins was effectively inhibited from the shrunk hydrogel and activated from the swollen hydrogel film. Overall, the electrochemically produced local pH changes allowed control over the biomolecule release process. The experimental observations from a confocal fluorescence microscope and fluorescence spectroscopy obtained using five fluorescently labeled proteins with different molecular weights (MW) and isoelectric points (pI) showed, that these parameters are critically important for the efficiency of the release from the alginate hydrogel. While the release inhibition by applying +0.6 V was consistently effective and can be maintained as long as the positive potential applied, the release activation was different depending on the protein molecular size, being more effective for smaller species, and molecule charge, being more effective for negatively charged species.

Therefore, a deeper study on the effect of pI on protein release was performed. In particular, native chymotrypsin was chosen as a model protein, and its pI (8.9) was chemically lowered using a specific linker group. Using different ratios of the linker in the reaction, it was possible to produce batches having different pIs (the lowest pI of 4.3), allowing to improve release efficiency from alginate hydrogel compared to the native protein. The confirmation of successful pI modifications was done with mass spectrometry.

Presenting Author: Anna Tverdokhlebova Clarkson University

Presenting Author Biography: Anna Tverdokhlebova earned her B.Sc. in Biotechnology from MIREA-Russian Technological University in Moscow, Russia, in 2018. Through a prestigious Double Degree program, she obtained her M.Sc. in Biotechnology from MIREA-Russian Technological University and M.Sc. in Chemical Engineering from Politecnico di Milano in Milan, Italy, after just two years.

In 2021, Anna joined the research groups of Prof. Katz and Prof. Melman at Clarkson University in Potsdam, NY, where she is currently pursuing her PhD. Her research focuses on the innovative on-demand release of biomolecules, particularly from alginate hydrogels, using electrochemical stimuli. Anna's work holds promising potential for advancements in biomedical applications and controlled drug delivery systems.

Authors:

Anna Tverdokhlebova Clarkson University
Ilya Sterin Clarkson University
Oleh Smutok Clarkson University
Evgeny Katz Clarkson University