title: Ultrasensitive protein concentration detection on a micro/nanofluidic enrichment chip using fluorescence quenching.
abstract: A micro/nanofluidic enrichment device combined with the Förster resonance energy transfer (FRET) technique has been developed for sensitive detection of trace quantities of protein. In this approach, sample protein is first adsorbed on gold nanoparticles (AuNPs) to occupy part of the AuNP surface. Then, dye-labeled protein is added, which adsorbs to the residual active sites of the AuNP surface, saturating the AuNP surface with protein molecules. The unadsorbed dye-labeled protein remains in a free state in the system. Keeping a fixed amount of dye-labeled protein, a high concentration of sample protein leads to more free dye-labeled protein molecules remaining in the system, and thus a larger photoluminescence signal. Under the action of an electric field, the free dye-labeled protein molecules can be efficiently enriched in front of the nanochannel of a micro/nanofluidic chip, which greatly amplifies the magnitude of the photoluminescence and improves the detection sensitivity. As a demonstration, bovine serum albumin (BSA) and fluorescein isothiocyanate-labeled dog serum albumin (FITC-DSA) are used as sample and fluorescent proteins, respectively. Using the proposed strategy, a detection limit of BSA as low as 2.5 pg/mL can be achieved, which is more than 10(3) times lower than the reported minimums in most sensitive commercial protein quantification methods.
authors.affiliation: †State Key Laboratory of Analytical Chemistry for Life Science, School of Chemistry and Chemical Engineering, Nanjing University, Collaborative Innovation Center of Chemistry for Life Sciences, Nanjing 210093, China.|‡Key Laboratory of Biomedical Functional Materials, Department of Physical Chemistry, School of Science, China Pharmaceutical University, Nanjing 211198, China.
authors.forename: Chen
authors.initials: C
authors.lastname: Wang
authors.affiliation: †State Key Laboratory of Analytical Chemistry for Life Science, School of Chemistry and Chemical Engineering, Nanjing University, Collaborative Innovation Center of Chemistry for Life Sciences, Nanjing 210093, China.
authors.forename: Yi
authors.initials: Y
authors.lastname: Shi
authors.affiliation: †State Key Laboratory of Analytical Chemistry for Life Science, School of Chemistry and Chemical Engineering, Nanjing University, Collaborative Innovation Center of Chemistry for Life Sciences, Nanjing 210093, China.
authors.forename: Jiong
authors.initials: J
authors.lastname: Wang
authors.affiliation: †State Key Laboratory of Analytical Chemistry for Life Science, School of Chemistry and Chemical Engineering, Nanjing University, Collaborative Innovation Center of Chemistry for Life Sciences, Nanjing 210093, China.
authors.forename: Jie
authors.initials: J
authors.lastname: Pang
authors.affiliation: †State Key Laboratory of Analytical Chemistry for Life Science, School of Chemistry and Chemical Engineering, Nanjing University, Collaborative Innovation Center of Chemistry for Life Sciences, Nanjing 210093, China.
authors.forename: Xing-Hua
authors.initials: XH
authors.lastname: Xia
mesh_terms: D000818:Animals; D002417:Cattle; D004285:Dogs; D005453:Fluorescence; D031541:Fluorescence Resonance Energy Transfer / Q000295:instrumentation / Q000379:methods*; D006046:Gold / Q000737:chemistry*; D053768:Metal Nanoparticles / Q000737:chemistry*; D046210:Microfluidic Analytical Techniques / Q000295:instrumentation / Q000379:methods*; D012680:Sensitivity and Specificity; D012709:Serum Albumin / Q000032:analysis; D012710:Serum Albumin, Bovine / Q000032:analysis*
chemical_list: D012709:Serum Albumin; D012710:Serum Albumin, Bovine; D006046:Gold
keywords: AuNPs; FRET; enrichment; micro/nanofluidics; protein detection