Protein Binding-Induced Surfactant Aggregation Variation: A New Strategy of Developing Fluorescent Aqueous Sensor for Proteins

Abstract

Novel strategies of developing fluorescent sensors for proteins are highly demanded. In this work, we particularly synthesized a cholesterol-derivatized pyrene probe. Its fluorescence emission is effectively tuned by the aggregation state of a cationic surfactant dodecyltrimethylammonium bromide (DTAB). The used probe/DTAB assemblies exhibit highly sensitive ratiometric responses to pepsin and ovalbumin egg (o-egg) with detection limits of 4.8 and 18.9 nM, respectively. The fluorescence changes indicate the protein-surfactant interaction leads to further aggregation of DTAB assemblies. The results from Tyndall effect and dynamic light scattering verify this assumption. The responses to pepsin and o-egg are due to their strong electrostatic or hydrophobic interaction with DTAB assemblies at pH 7.4. The present noncovalent supramolecular sensor represents a novel and simple strategy for sensing proteins, which is based on the encapsulated fluorophore probing the aggregation variation of the surfactant assemblies.

Fluorescent Ensemble Based on Bispyrene Fluorophore and Surfactant Assemblies: Sensing and Discriminating Proteins in Aqueous Solution

“…It is worth noting that the currently observed quenching responses to metalloproteins and ratiometric responses to other nonmetalloproteins such as BSA and BLG were not observed in our previous sensor system based on monopyrene fluorophore/DTAB assemblies, which exhibit only ratiometric responses to PS and O-egg. 31 The multiple sensing behaviors of the present supramolecular ensemble could be due to the use of bispyrene fluorophores and the different locations of the probe in DTAB assemblies. The effective quenching of the present ensemble by metalloproteins suggests that the location of probe 1 in DTAB assemblies is accessible to the added proteins, which is more likely at the interface between the surfactant assembly and aqueous solution.…”

“…Further increasing DTAB concentration will lead to total monomer emission, which occurs at 9 mM DTAB. As we learned from our previous studies, the protein binding may facilitate further aggregation of DTAB assemblies and induce the probe to go through changes from one emission state to another, 31 which is dependent on the adopted DTAB concentration. Therefore, 6 mM DTAB was selected to incorporate the present probe to construct a fluorescent ensemble for sensing proteins because the probe exhibits monomer−excimer coemission in this DTAB solution, which may easily change forward to monomer-dominated emission or backward to excimerdominated emission.…”

“…31 Moreover, this strategy provides a novel sensing mechanism, where the fluorophore probes the aggregation changes of surfactant assemblies upon protein binding. The developed ensemble based on a cholesterolmodified pyrene-based fluorophore and dodecyltrimethylammonium bromide (DTAB) assemblies shows selective ratiometric responses to pepsin and O-egg over a series of tested proteins.…”

Pyrene Derivative Emitting Red or near-Infrared Light with Monomer/Excimer Conversion and Its Application to Ratiometric Detection of Hypochlorite

“…Thanks to the predictability of the two luminescence signals, pyrene moieties have been introduced in the design of numerous ratiometric sensors as reporters and other functional 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 3 materials [17][18][19][20][21][22][23][24][25][26][27][28] . The ratiometric mode of pyrene-involved sensing, which involves the synchronous measurement of two fluorescence signals at different wavelengths followed by calculation of their intensity ratio, is an elegant approach for achieving ratiometric sensing by simply using a single fluorophore molecule and is aimed to overcome unfavorable effects of the turn-on mode sensing.…”

Sodium Acetate Coated Tenofovir-Loaded Chitosan Nanoparticles for Improved Physico-Chemical Properties

“…The color of the solution changes from colorless to milky (Tyndall effect) indicating the instantaneously formation of the uncoated chitosan NPs through ionic gelation (Fig. S1 B) (30). The EE % of TFV in uncoated chitosan NPs is indeed low before freeze drying (Table II).…”