7th Asia-Pacific Conference on Plasma Physics, 12-17 Nov, 2023 at Port Messe Nagoya

Biofunctionalization of Chitosan-Acrylic Acid Hydrogel through AtmosphericPressure Plasma-initiated Polymerization

K.L.M. Taaca1,2, K. Amemiya3, E.I. Prieto4 and M.R. Vasquez Jr.1
1Department of Mining, Metallurgical and Materials Engineering, College of Engineering,
University of the Philippines-Diliman, Philippines, 2 Materials Science and Engineering Program,College of Science, University of the Philippines-Diliman, Philippines, 3 Institute of Materials
Structure Science, High Energy Accelerator Research Organization, KEK, Japan, 4 National
Institute of Molecular Biology and Biotechnology, College of Science, University of thePhilippines-Diliman, Philippines
e-mail (speaker): kmtaaca@up.edu.phHydrogel is among the early polymeric biomaterials
considered for human use. This is because its
functionality resembles the natural extracellular matrix(ECM). The 3D hydrophilic network of hydrogel,however, depends on the polymer selection and thecrosslinking approach. These factors are critical incontrolling the properties of hydrogel, such as porosity
and swelling capacity. In this study, chitosan-acrylic acid
(2.5Cs-4AA) blends were transformed into hydrogels forpossible use in biomedical applications. Chemical
crosslinkers
suchasglutaraldehyde
andN,N’-methylenebisacrylamide (MBA) can leave traces in
the network of the Cs-AA hydrogel, leading to possible
adverse effect of hydrogel when used to humans. Hence,the study employs an atmospheric pressure plasma(APP) treatment step as an alternative to the chemical
crosslinking route of Cs-AA hydrogels.
There is an increasing interest in modifying polymer
solutions using atmospheric pressure plasma (APP). APP
sources create a rich environment of reactive species
even at low temperatures. As shown in Figure 1 (i),increasing the treatment time to 5 min (2.5Cs-4AA-5T)
reaches a process temperature of about 36.95±2.62°C.
Possible change in the reactive species was observed in
the change in the pH and electrical conductivity valuesof the 2.5Cs-4AA-T blends. The change in the pH andelectrical conductivity may be attributed to the possible

formation of reactive species such as electrons, hydrogen
peroxides, and nitrates.
Since the APP treatment creates a humid atmosphere forthe reactive species generation, it also caused theplasma-treated 2.5Cs-4AA samples to evaporate. Hence,the pristine 2.5Cs-4AA hydrogel has a higher yield butwith the cost of having decreased porosity percentage,shown in Figure 1 (ii). The plasma-treated samples
resulted to more pores possible because there were more
bubbles formed during the plasma process. Lastly, Figure1(iii) shows the NEXAFS C K edge measurement of2.5Cs-4AA-T samples collected at (a) normal and (b)magic incidence angles. The angular-dependent
NEXAFS was acquired in this study since the orientationof the chemical groups of 2.5Cs-4AA-T along thesurface is crucial for biomedical applications. Based on
the spectra, the surface molecular orientation of the2.5Cs-4AA-T samples was altered when plasmatreatment was employed in the hydrogel synthesis.
Summarizing these results, the use of plasma treatment
during hydrogel synthesis improved the functionality of
the 2.5Cs-4AA hydrogels. This work is supported by theDepartment of Science and Technology-Science
Education Institute (DOST-SEI) through the Accelerated
Science and Technology Human Resource Development
Program (ASTHRDP).

Figure 1 Physicochemical properties of the 2.5Cs-4AA-T samples. (i) Temperature, pH, and electrical conductivity;of the 2.5Cs-4AA-T samples (liquid state), (ii) yield and porosity of 2.5Cs-4AA-T samples (solid state), (iii) angulardependent NEXAFS of 2.5Cs-4AA-T samples (solid state).