title: Enzyme-specific sensors via aggregation of charged p-phenylene ethynylenes.
abstract: Chemical and biological sensors are sought for their ability to detect enzymes as biomarkers for symptoms of various disorders, or the presence of chemical pollutants or poisons. p-Phenylene ethynylene oligomers with pendant charged groups have been recently shown to have ideal photophysical properties for sensing. In this study, one anionic and one cationic oligomer are combined with substrates that are susceptible to enzymatic degradation by phospholipases or acetylcholinesterases. The photophysical properties of the J-aggregated oligomers with the substrate are ideal for sensing, with fluorescence quantum yields of the sensors enhanced between 30 and 66 times compared to the oligomers without substrate. The phospholipase sensor was used to monitor the activity of phospholipase A1 and A2 and obtain kinetic information, though phospholipase C did not degrade the sensor. The acetylcholinesterase sensor was used to monitor enzyme activity and was also used to detect the inhibition of acetylcholinesterase by three different inhibitors. Phospholipase A2 is a biomarker for heart and circulatory disease, and acetylcholinesterase is a biomarker for Alzheimer's, and indicative of exposure to certain pesticides and nerve agents. This work shows that phenylene ethynylene oligomers can be tailored to enzyme-specific sensors by careful selection of substrates that induce formation of a molecular aggregate, and that the sensing of enzymes can be extended to enzyme kinetics and detection of inhibition. Furthermore, the aggregates were studied through all-atom molecular dynamics, providing a molecular-level view of the formation of the molecular aggregates and their structure.
authors.affiliation: Center for Biomedical Engineering, Department of Chemical and Biological Engineering, and ‡The Nanoscience and Microsystems Engineering Program and Department of Chemistry and Chemical Biology, University of New Mexico , Albuquerque, New Mexico 87131-1341, United States.
authors.forename: Eric H
authors.initials: EH
authors.lastname: Hill
authors.forename: Yue
authors.initials: Y
authors.lastname: Zhang
authors.forename: Deborah G
authors.initials: DG
authors.lastname: Evans
authors.forename: David G
authors.initials: DG
authors.lastname: Whitten
mesh_terms: D000110:Acetylcholinesterase / Q000378:metabolism; D000480:Alkynes / Q000737:chemistry* / Q000378:metabolism; D000838:Anions / Q000737:chemistry; D015374:Biosensing Techniques; D002412:Cations / Q000737:chemistry; D004987:Ethers / Q000737:chemistry* / Q000378:metabolism; D007700:Kinetics; D056004:Molecular Dynamics Simulation; D010715:Phosphatidylglycerols / Q000737:chemistry / Q000378:metabolism; D010740:Phospholipases / Q000378:metabolism*; D054466:Phospholipases A1 / Q000378:metabolism; D054467:Phospholipases A2 / Q000378:metabolism; D013379:Substrate Specificity; D010738:Type C Phospholipases / Q000378:metabolism
chemical_list: D000480:Alkynes; D000838:Anions; D002412:Cations; D004987:Ethers; D010715:Phosphatidylglycerols; C436384:phenyleneethynylene; C051388:1,2-dioleoyl-sn-glycero-3-phosphoglycerol; D010740:Phospholipases; D054466:Phospholipases A1; D054467:Phospholipases A2; D000110:Acetylcholinesterase; D010738:Type C Phospholipases
keywords: biomarkers; biosensing; chemical sensing; enzyme sensing; fluorescence quenching; molecular aggregation