Chitosan-Alginate Bioplastics

Chitosan, a derivative of a structural component of insect and crustacean shells can be reacted with alginate, a seaweed extract to make chitosan-alginate bioplastics. There is an extensive literature on the use of these materials both as plastic alternatives and in the biomedical field as for example drug delivery systems which can release pharmaceuticals over time after ingestion or implantation in the body. 

The original bioplastic experiments implemented in the general chemistry lab were developed by Lexi Ward ('19) and a description of how this is implemented in a course based undergraduate research experience (CURE) was published in the Journal of Chemical Education in 2019 (https://pubs.acs.org/doi/abs/10.1021/acs.jchemed.8b00666) 

While the second semester general chemistry laboratory has allowed students to work during the semester on a mini-research project utilizing these chitosan-alginate bioplastics, my lab has begun a more systematic investigation of release and uptake of materials from these films. Past student researchers have looked at the movement into and out of the bioplastics of a range of materials including common food dyes, other colored pigments and pharmaceuticals. 

Some of these release studies which have utilized a range of different salt solutions have revealed the nature of the solution used to immerse the bioplastic has a critical effect on release rate and it is not simply ionic strength as we initially thought but also the identity of the salt that impacts release. Looking at different food dyes has also revealed that the identity of the dye also affects the rate of release and so future efforts will work on looking at systematic variations of these parameters and more. The hope is to gain not only a better understanding of the complex processes behind the release of materials from our bioplastics but also hopefully develop new aspects of this area for implementation into the general chemistry lab. 

Food Dyes, Pigments, Colors, Candy and Chromatography

Food dyes such as Red 40, Yellow 5 and Blue 1 are ubiquitous in a wide range of products in the world these days. Their obvious colors which arise from strong absorbance of various wavelengths of visible light mean very small concentrations can be easily measured in the general chemistry laboratory environment whilst generating little to no toxic waste. Yet when several of these dyes are present, it can be difficult to isolate and measure individual concentrations due to overlapping signals in their visible spectra and the requirement for separation of such mixtures into their individual components is necessary for quantification. 

The generous donation of a High Performance Liquid Chromatography (HPLC) system by Analytical Instruments (https://analyticalinstrument.com/) provided the incentive to design a series of new experiments looking at introducing chromatography to the general chemistry lab as a means of quantifying the amounts of food dyes such as Red 40 and Yellow 5 in commercial food colors such as those purchased at the grocery store and in a range of candy samples.

The differences in the structures of the various food dyes which results in differing polarities make them ideal candidates for separation and analysis by both thin layer chromatography (TLC) and HPLC.  Experiments were developed in the summer of 2019 by Sofia Palme ('21) and Andrew H. Johnson ('20) and succesfully implemented in the teaching lab at Concordia in Fall 2019 and refined and adapted for COVID-times in Fall 2020 and we published these experiments in the Journal of Chemical Education in January 2024 (https://pubs.acs.org/doi/abs/10.1021/acs.jchemed.3c00673) 

In addition, the strong color of these materials makes measuring the rates of reactions very straightforward and we have some provisional data on comparing the rates of reactions for the various food colors with oxidizing agents such as bleach. 

Finally, as well as our work on various food dyes, I am also interested in developing new activities incorporating HPLC and related chromatography techniques for the general chemistry audience.  

Initial studies on sulfa drugs, a commonly used anti bacterial allowed members of the Wyllie research lab to develop methods for the measurement of these drugs by HPLC and look at the effects of various degradation methods including chlorine dioxide, potassium ferrate and oxone / cobalt salts. The information gained in these summer studies which was disseminated by the students at various conferences, both local and national also aided in developing new activities and refining the existing experiments in the second semester general chemistry teaching laboratory. 

Contact Information and Links:

Email: Wyllie@cord.edu

Official Faculty Page (includes biography and CV):
https://www.concordiacollege.edu/directories/faculty-staff/details/dr-graeme-r-a-wyllie/

LinkedIn:
https://www.linkedin.com/in/graeme-wyllie-4b005a19a/

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Concordia Chemistry Department
https://www.facebook.com/Concordia-College-Chemistry-Department

American Chemical Society
(https://www.acs.org/ )

Red River Valley Local Section of ACS
https://sites.google.com/view/rrvacs/home?authuser=0

Sigma Zeta (Nation Science and Mathematics Honor Society)
(www.sigmazeta.org/)