title: Optically addressed droplet-based protein assay.
abstract: We demonstrate a new method for performing protein assays with very small volumes ( approximately 1.7 muL to 14 pL). Using a laser to modify local surface energy, we manipulate, fuse, and mix droplets containing horseradish peroxidase and its substrates. A detection limit of approximately 30 attomoles of reacting enzyme was measured by optical absorption. We discuss the possibility of extending this lower limit to zeptomoles of enzyme.
authors.affiliation: Molecular Physics Laboratory, SRI International, 333 Ravenswood Avenue, Menlo Park, California 94025, USA.
authors.forename: Kenneth T
authors.initials: KT
authors.lastname: Kotz
authors.forename: Yu
authors.initials: Y
authors.lastname: Gu
authors.forename: Gregory W
authors.initials: GW
authors.lastname: Faris
mesh_terms: D052160:Benzothiazoles; D006735:Horseradish Peroxidase / Q000032:analysis / Q000737:chemistry; D006861:Hydrogen Peroxide / Q000737:chemistry; D007202:Indicators and Reagents / Q000737:chemistry; D046210:Microfluidic Analytical Techniques / Q000295:instrumentation / Q000379:methods*; D055095:Optics and Photonics / Q000295:instrumentation; D010084:Oxidation-Reduction; D011137:Polystyrenes / Q000737:chemistry; D011506:Proteins / Q000032:analysis* / Q000737:chemistry; D013451:Sulfonic Acids / Q000737:chemistry; D013500:Surface Tension
chemical_list: D052160:Benzothiazoles; D007202:Indicators and Reagents; D011137:Polystyrenes; D011506:Proteins; D013451:Sulfonic Acids; C002502:2,2'-azino-di-(3-ethylbenzothiazoline)-6-sulfonic acid; D006861:Hydrogen Peroxide; D006735:Horseradish Peroxidase