Louisa Oze

Mentor: Naznin Sultana Texas Undergraduate Medical Academy

Introduction: Water uptake is a crucial characteristic of biodegradable polymers because this process can be detrimental or advantageous for the material’s properties by graceful degradation or damage in the case of excessive absorption. There is little understanding of the relationship between water uptake and the properties of polymeric composite substrates. Chitosan is a natural biodegradable polymer, and Pectin is a natural product, which has antibacterial properties; together they make great materials for water uptake analysis for biomedical applications. The ingress of water into polymer-based substances can have both adverse and beneficial effects on their properties. Hydrolysis and microcrack can be formed due to water exposure [1,2]. On the other hand, the breakdown of polymer substrates can occur due to excessive water uptake. The water uptake and diffusion characteristics of polymeric composite substrates have been rarely assessed and reported. The specific research hypothesizes that the classical diffusion theories can be applied to solvent-cast Chitosan and pectin-based substrates [3,4]. Objectives/Goals: The objectives of the study were to produce thin films using solvent casting and evaporation techniques and to analyze its water uptake and its diffusion properties with pectin and chitosan. Materials and Methods: Pectin and chitosan were obtained from Sigma- Aldrich, and the acetic acid was the analytical grade. 0.25g of chitosan was weighed and placed in beaker 1, 0.25g chitosan plus 0.05g of pectin was weighed and put in beaker 2, and 0.25g chitosan plus 0.1g pectin was weighed and placed in beaker 3. Then, 2ml of acetic acid and 98 ml of distilled water were combined to create a solvent. 20 ml of solvent was added to each beaker. Afterward, the samples were mixed thoroughly. The mixtures were placed in Petri dishes for molding to occur. The new films were weighed and placed in centrifuge tubes, and 20ml of water was added to each of them. The tubes were placed in a water bath at 37 degrees Celsius and observed. Results and Discussion: Figure 1a shows the thin films prepared from different compositions of pectin and Chitosan using the solvent casting method. It took approximately 7days for the complete evaporation of solvents under a chemical fume hood. The films were transparent, and the dispersion of pectin was observable in pectin/chitosan thin films. The incorporation of higher content of pectin made the film unstable. An increase of pectin concentration in the mixture reduced the mixture's solubility and resulted in more solid clumps. There was an apparent relationship between water uptake and the composition of the films. Water uptake increased with time in all three samples but with a significant amount of uptake in samples with pectin. In an examination of the samples with pectin, the one containing the highest composition of pectin had the greatest water uptake (Figure 1b).

(a) (b) Figure 1: (a) Fabrication of pectin/chitosan thin films; (b) Water uptake properties Conclusion(s) or Summary: Pectin and chitosan-based solvent cast thin films were successfully fabricated. Water uptake properties were evaluated. Further study on diffusion properties and the cytotoxicity of chitosan-pectin composite films are needed.

0.1 300.00% 0.08 0.06 200.00% 0.04 100.00% 0.02

WATER UPTAKE IN 28 DAYS

0 0.00%

SAMPLE 1 SAMPLE 2 SAMPLE 3

References:

5. Sultana, N. and Khan, T.H. Water absorption and diffusion characteristics of nanohydroxyapatite (nHA) and poly(hydroxybutyrate-co-hydroxy valerate-) based composite tissue engineering scaffolds and nonporous thin films, Journal of Nanomaterials, vol. 2013, Article ID 479109, 8 pages, 2013. Page 133 of 3

6. Crank, J., and Park, G.S., Eds., Diffusion in Polymers, Academic Press, New York, NY, USA, 1977. 7. Di Martino, A., Sittinger, M. and Risbud, M.V. (2005). Chitosan: a versatile biopolymer for orthopedic tissue engineering. Biomaterials. 26 (30): 5983-5990. 8. De Souza, B., Carla, F., Francielle, R., Bernard, D., Mantovani, D., Moraes, A. M. 2019. Comparative study on complexes formed by chitosan and different polyanions: Potential of chitosan-pectin biomaterials as scaffolds in tissue engineering. Int. J. Biomacromol. 132:178-189

Awardee and Student:

Dr. Naznin Sultana is a Research Scientist with research interests in Biomaterials, Tissue Engineering, and Drug Delivery. Louisa Oze is a Junior, majoring in Chemistry.