Discipline: Technology and Engineering
Subcategory: Materials Science
Zuleika Oquendo - University of Puerto Rico at Mayaguez
Co-Author(s): John E. López,University of Puerto Rico, Mayagüez, PR; Amanda M. Quintero,University of Puerto Rico, Mayagüez, PR; Yamalis López,University of Puerto Rico, Mayagüez, PR; Christian McRobert,University of Puerto Rico, Mayagüez, PR; John L. Soto,University of Puerto Rico, Mayagüez, PR; Katyria M. Torres,University of Puerto Rico, Mayagüez, PR; Luis E. Orta,University of Puerto Rico, Mayagüez, PR; Karimar Amador,University of Puerto Rico, Mayagüez, PR; Kenneth M. Serrano,University of Puerto Rico, Mayagüez, PR; Oscar M. Suarez, University of Puerto Rico, Mayagüez, PR
Water is a vital natural resource for human existence, hence, the development of economical, non-toxic, and efficient methods of water purification is a raising concern among the scientific community. In this context, the present study sought to develop a biocomposite made of chitosan and titanium dioxide (anatase polymorph, TiO2), that can be used in a water filtration system as a biocidal constituent. Chitosan is an abundant and non-toxic biopolymer composed by D-glucosamine and N-acetyl-D-glucosamine. It has the ability of forming films and gels with antibacterial properties. Further, anatase has a photocatalytic effect when exposed to ultraviolet (UV) light that results in the liberation of an active oxygen specie that disrupts the bacteria membrane unavailing the DNA process and causing cell death.
To prove the hypothesis that our biocomposite would have antibacterial effects, we tested it on gram positive and gram negative bacteria. As it is well known that the difference between them is the wall cell thickness, the first one having just one and the other two. In this context, Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus) were used as representative specimens of both bacteria types. The affinity of chitosan towards the gram positive bacteria (S. aureus) and the photocatalytic effect of TiO2 attacking the gram negative one (E. coli) give to the material the ability of affecting a large range of water bacterial contamination.
We synthetized the biocomposite by mixing chitosan, deionized water, and TiO2 particles using a sonicator and magnetic agitator at 55°C for 48 hours. At the same time, E. coli and S. aureus colonies were incubated. Thereupon, a spectrophotometer allowed assessing the bacteria behaviour for an 8-hour period in contact with the biocomposite exposed to UV light. The same procedure was used without UV light as a control curve to compare the results. Using the data provided by the instrument we were able to generate bacteria growing curves. The preliminary results shown that the biocomposite present antibacterial effects. With respect to the presence of UV light, the results did not shown a significant difference between the controls and the experimental group. We are currently investigating the possible reasons for these finds. As a future research question, we will investigate the photocatalytic effect of TiO2 in the visible light, in order to compare it with our resents results.
References: Archana, D., Singh, B. K., Dutta, J., & Dutta, P. K. (2013). In vivo evaluation of chitosan-PVP-titanium dioxide nanocomposite as wound dressing material. Carbohydrate Polymers. https://doi.org/10.1016/j.carbpol.2013.03.034
Kumar Dutta, P., Dutta, J., & Tripathi, V. S. (2004). Chitin and chitosan: Chemistry, properties, and applications. Journal of Scientific & Industrial Research, 63, 20?31.
Santiago De Alvarenga, E. (n.d.). Characterization and Properties of Chitosan.
Funder Acknowledgement(s): Nanotechnology Center UPRM-CREST
Faculty Advisor: Oscar M. Suarez, firstname.lastname@example.org
Role: The research is divided into two main procedures, the biocomposite characterization, and the bacteria growth curve. I had been able to perform both at least 10 times. As well, I created a program with the purpose of improving the process of analyzing the data provided by the instruments, by which an hour of data analyzing was reduced to 10 minutes or less. Also, I work in a #2 biosecurity laboratory, which requires taking the necessary precautions for safeguard the pathogens that can damage the experiment or cause human's disease.