probes in a dry-reagent strip biosensor for protein analysis. Analytical chemistry.pdf

Aptamer-Functionalized Gold Nanoparticles as Probes in a Dry-Reagent Strip Biosensor for Protein Analysis Hui Xu,?,? Xun Mao,? Qingxiang Zeng,?,? Shengfu Wang,*,?,? Abdel-Nasser Kawde,§ and Guodong Liu*,? College of Chemistry and Chemical Engineering, Hubei University, Wuhan 430062, P. R. China, Department of Chemistry and Molecular Biology, North Dakota State University, Fargo, North Dakota 58105, Department of Chemistry, King Fahd University of Petroleum and Minerals, Dhahran 31261, Saudi Arabia The highly specific molecular recognition properties of aptamers are combined with the unique optical properties of gold nanoparticles for the development of a dry-reagent strip biosensor that enables qualitative (visual)/quantita- tive detection of protein within minutes. A model system comprising thrombin as an analyte and a pair of aptamer probes is used to demonstrate the proof-of-concept on the conventional lateral flow test strip. The assay avoids the multiple incubation and washing steps performed in most current aptamer-based protein analyses. Although quali- tative tests are realized by observing the color change of the test zone, quantitative data are obtained by recording the optical responses of the test zone with a portable “strip reader”. The response of the biosensor is linear over the range of 5-100 nM of thrombin with a detection limit of 2.5 nM (S/N ) 3). By comparing the analytical perfor- mances of the aptamer-based strip biosensor with the antibody-based strip sensor, we can demonstrate that aptamers are equivalent or superior to antibodies in terms of specificity and sensitivity, respectively. The sensor was used successfully for detection of thrombin in human plasma samples. It shows great promise for use of aptamer-functionalized gold nanoparticle probes in dry- reagent strip biosensors for point-of-care or in-field detec- tion of proteins. The detection and quantification of extremely low concentra- tions of proteins play pivotal roles in basic dis