Publication Date

2014-08-20

Availability

Open access

Embargo Period

2014-08-20

Degree Type

Dissertation

Degree Name

Doctor of Philosophy (PHD)

Department

Chemistry (Arts and Sciences)

Date of Defense

2014-08-08

First Committee Member

Sylvia Daunert

Second Committee Member

Leonidas Bachas

Third Committee Member

Angel Kaifer

Fourth Committee Member

Sapna Deo

Abstract

Nature has endowed us with eloquently designed biosystems which can be applied to a number of analytical applications. Advances in biotechnology have allowed for bacteria and the proteins found therein to be exploited throughout the years for the development of designer analytical systems. Herein, we have exploited genetically designed bacterial whole-cell systems and proteins for biomedical and environmental applications. First, we have demonstrated the use of a whole-cell sensing system based on the quorum sensing regulatory protein LasR as a tool to elucidate interkingdom communication and better understand host-microbiome interactions. Specifically, the role of serotonin as a bacterial signaling molecule was investigated in vitro by examining virulence phenotypes of the opportunistic pathogen P. aeruginosa such as elastase production and biofilm formation. Next, we show the applications of genetically encoded biosensors integrated into diverse organisms -bacteria and worms- for in situ and remote detection of arsenic. To this end, first we demonstrate the utility of the genetically encoded biosensor incorporated in bacterial cells for the detection of arsenic in environmental samples and organoarsenicals, a class of arsenical compounds used as chemical warfare agents. The preservation and transport of the sensor was enhanced by forming bacterial spores, which were deposited on paper strips and used as inexpensive, transportable, on-site detection. In addition, we incorporated the genetically encoded biosensor into a model living organism, Caenorhabditis elegans as a model for remote sensing capabilities. From this work, we exploit spores as packaging for whole-cell biosensors and incorporate them into wax printed paper strips for the development of on-site analytical detection systems. Finally, we employ a thermophilic dehalogenase from Sulfolobis tokodaii to demonstrate remote activation of enzymatic activity via iron oxide nanoparticles co-encapsulated with the enzyme in a hydrogel.

Keywords

whole-cell biosensor; serotonin; hydrogel; arsenic

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