This laboratory exercise integrates chemistry and biology
concepts
to give third/fourth-year undergraduate students an opportunity to
apply knowledge from different subject areas to address a real-world
biomedical issue such as pathogen inhibition using composite materials.
It involves the preparation of a bacteria-derived cellulosic biopolymer
through microbial cultivation, impregnation of the bacterial cellulose
(BC) with silver nanoparticles (AgNPs), followed by the analysis of
the materials and the antimicrobial properties of the biomaterial-AgNPs
composites. The methods are relatively simple and use inexpensive
chemicals. A Tollens type approach is adopted to produce silver nanoparticles-bacterial
cellulose (AgNPs-BC) composites by the reduction of [Ag(NH3)2]+ complex embedded in the cellulose matrix.
The samples were dried by two different methods: freeze-drying or
vacuum-drying. The dried AgNPs-BC films were evaluated for antimicrobial
properties against a test organism, in this example, Pseudomonas aeruginosa, a Gram-negative biosafety
containment level 2 (BSL 2) bacterium, using an agar diffusion test.
For additional flexibility and customization, options for dividing
the chemistry/biology content of this laboratory into smaller units
with an emphasis on characterization techniques of nanomaterials for
chemistry majors are also discussed.
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