Quantitation, Visualization, and Monitoring of Conformational Transitions of Human Serum Albumin by a Tetraphenylethene Derivative with Aggregation-Induced Emission Characteristics

Abstract

Human serum albumin (HSA) is a major protein component of blood plasma, and its assay is of obvious value to biological research. We, herein, present a readily accessible fluorescent bioprobe for HSA detection and quantitation. A nonemissive tetraphenylethene derivative named sodium 1,2-bis[4-(3-sulfonatopropoxyl)phenyl]-1,2-diphenylethene (BSPOTPE) is induced to emit by HSA, showing a novel phenomenon of aggregation-induced emission (AIE). The AIE bioprobe enjoys a broad working range (0-100 nM), a low detection limit (down to 1 nM), and a superior selectivity to albumins. The fluorescent bioassay is unperturbed by the miscellaneous bioelectrolytes in the artificial urine. The AIE luminogen can also be used as a rapid and sensitive protein stain in gel electrophoresis for HSA visualization. Utilizing the AIE feature of BSPOTPE and the Forster resonance energy transfer from HSA to BSPOTPE, the unfolding process of HSA induced by guanidine hydrochloride is monitored, which reveals a multistep transition with the involvement of molten globule intermediates. Computational modeling suggests that the AIE luminogens dock in the hydrophobic cleft between subdomains IIA and IIIA of HSA with the aid of hydrophobic effect, charge neutralization, and hydrogen bonding interactions, offering mechanistic insight into the microenvironment inside the hydrophobic cavity.

New insight into protein–nanomaterial interactions with UV-visible spectroscopy and chemometrics: human serum albumin and silver nanoparticles

“…And HSA exhibits two representative negative bands in the ultraviolet region at 208 nm and 220 nm, which are assigned to the a-helix structure of the protein. 45 The addition of AgNPs to HSA led to a remarkable decrease in ellipticity of the band around 208 nm. The result denotes the structural alteration from a-helix conformation to b-sheet conformation, which is in good agreement with IR results.…”

Development of a red fluorescent light-up probe for highly selective and sensitive detection of vicinal dithiol-containing proteins in living cells

“…This is apparently due to the unfolding of rBSA and the hydrophobic pocket in rBSA is destroyed. 27 As a result, the probe gets more exposed to the polar environment, which is undesirable for fluorescence emission. The above results reveal the essential role of the hydrophobic cavities of the protein folding structure in the present sensing system.…”

New Chemo-/Biosensors with Silole and Tetraphenylethene Molecules Based on the Aggregation and Deaggregation Mechanism

“…Bovine serum albumin (BSA) at a concentration as low as 500 ng ml À1 was successfully detected with 14. Furthermore, the protein detection with 14 was not subject to interferences from the miscellaneous bioelectrolytes in artificial urine, hence it was possible to determine the human serum albumin (HSA) level in body fluids with 14 [23]. Based on the finding that the fluorescence of 14 cannot be switched on by denatured proteins that lack hydrophobic cavities, the fluorescence enhancement of 14 in the presence of albumin is attributed to the hydrophobic interactions involving hydrophobic pockets within BSA.…”

“…AIE molecule 14 with two anionic moieties was also demonstrated to be a versatile tool in monitoring protein conformational transitions and fibrillation [23]. The nonemissive probe 14 was aggregated and its emission was enhanced upon addition of HSA; however, the denatured HSA in the presence of guanidine did not trigger the aggregation of 14.…”