Optically Addressed Droplet-Based Protein Assay

• Published in: Journal of the American Chemical Society Vol. 127; no. 16; pp. 5736 - 5737
• Main Authors: Kotz, Kenneth T, Gu, Yu, Faris, Gregory W
• Format: Journal Article
• Language: English
• Published: Washington, DC American Chemical Society 27-04-2005
• Subjects: Analytical, structural and metabolic biochemistry; Benzothiazoles; Biological and medical sciences; Fundamental and applied biological sciences. Psychology; General aspects, investigation methods; Horseradish Peroxidase - analysis; Horseradish Peroxidase - chemistry; Hydrogen Peroxide - chemistry; Indicators and Reagents - chemistry; Microfluidic Analytical Techniques - instrumentation; Microfluidic Analytical Techniques - methods; Optics and Photonics - instrumentation; Oxidation-Reduction; Polystyrenes - chemistry; Proteins; Proteins - analysis; Proteins - chemistry; Sulfonic Acids - chemistry; Surface Tension; Analysis method; Fluidic devices; Optical method; Biological macromolecule; Surface tension; Microminiaturization; Marangoni effect; Concentration gradient; Temperature gradient
• ISSN: 0002-7863; 1520-5126
• DOI: 10.1021/ja050249m

We demonstrate a new method for performing protein assays with very small volumes (∼1.7 μL 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 ∼30 attomoles of reacting enzyme was measured by optical absorption. We discuss the possibility of extending this lower limit to zeptomoles of enzyme.