title: Study on the fluorescent enhancement effect in terbium-gadolinium-protein-sodium dodecyl benzene sulfonate system and its application on sensitive detection of protein at nanogram level.
abstract: The co-luminescence effect in a terbium-gadolinium-protein-sodium dodecyl benzene sulfonate (SDBS) system is reported here. Based on it, the sensitive quantitative analysis of protein at nanogram levels is established. The co-luminescence mechanism is studied using fluorescence, resonance light scattering (RLS), absorption spectroscopy and NMR measurement. It is considered that protein could be unfolded by SDBS, then a efficacious intramolecular fluorescent energy transfer occurs from unfolded protein to rare earth ions through SDBS acting as a "transfer bridge" to enhance the emission fluorescence of Tb3+ in this ternary complex of Tb-SDBS-BSA, where energy transfer from protein to SDBS by aromatic ring stacking is the most important step. Cooperating with the intramolecular energy transfer above is the intermolecular energy transfer between the simultaneous existing complexes of both Tb3+ and Gd3+. The fluorescence quantum yield is increased by an energy-insulating sheath, which is considered to be another reason for the resulting enhancement of the fluorescence. Förster theory is used to calculate the distribution of enhancing factors and has led to a greater understanding of the mechanisms of energy transfer.
authors.affiliation: Key Laboratory of Colloid and Interface Chemistry (Shandong University), Ministry of Education, School of Chemistry and Chemical Engineering, Shandong University, Jinan 250100, PR China.
authors.forename: Changxia
authors.initials: C
authors.lastname: Sun
authors.forename: Jinghe
authors.initials: J
authors.lastname: Yang
authors.forename: Xia
authors.initials: X
authors.lastname: Wu
authors.forename: Shufang
authors.initials: S
authors.lastname: Liu
authors.forename: Benyu
authors.initials: B
authors.lastname: Su
mesh_terms: D000042:Absorption; D000818:Animals; D001557:Benzenesulfonates / Q000737:chemistry*; D002417:Cattle; D005453:Fluorescence; D005682:Gadolinium / Q000737:chemistry*; D009682:Magnetic Resonance Spectroscopy; D008832:Microchemistry / Q000379:methods*; D036103:Nanotechnology; D011506:Proteins / Q000032:analysis* / Q000737:chemistry*; D012680:Sensitivity and Specificity; D012710:Serum Albumin, Bovine / Q000032:analysis / Q000737:chemistry; D013050:Spectrometry, Fluorescence; D013725:Terbium / Q000737:chemistry*
chemical_list: D001557:Benzenesulfonates; D011506:Proteins; D013725:Terbium; D012710:Serum Albumin, Bovine; C001114:dodecylbenzenesulfonic acid; D005682:Gadolinium