Fluorescence “Turn-On” Enzyme-Responsive Supra-Amphiphile Fabricated by Host–Guest Recognition between γ-Cyclodextrin and a Tetraphenylethylene-Sodium Glycyrrhetinate Conjugate

Abstract

A novel fluorescence "turn-on" enzyme-responsive supra-amphiphile is developed based on the host−guest recognition between γ-cyclodextrin (γ-CD) and an amphiphilic tetraphenylethene-sodium glycyrrhetinate conjugate (TPE-SGA). The covalent amphiphile TPE-SGA displayed strong fluorescence in aqueous solution owing to the aggregation-induced emission. Upon addition of γ-CD, the fluorescence of TPE-SGA was effectively turned off due to the host−guest recognition with γ-CD prohibiting the aggregation of TPE-SGA in aqueous solution. The as-formed nonfluorescent supra-amphiphile (TPE-SGA/γ-CD) inherited the α-amylase-responsive property of γ-CD. In the presence of α-amylase, the fluorescence of the supra-amphiphile was gradually turned on owing to the hydrolysis of γ-CD, and the fluorescence intensity linearly correlated to the activity of α-amylase. This study enriches the field of supra-amphiphile on the basis of cyclodextrin-based host−guest chemistry and provides a novel strategy to construct fluorescence turn-on functioned self-assemblies. It is anticipated that the fluorescence turn-on supra-amphiphile has potential applications in biological analysis and diagnosis of pancreatic diseases.

Aggregation-induced emission luminogen based self-healing hydrogels fluorescent sensors for α-amylase

“…The intensity of the fluorescence rapidly decreases with the increasing molar ratios of the Ac-γ-CD to TPE units. 41 If the molar ratios of the Ac-γ-CD to TPE are higher than 7 : 1, the fluorescence emission shows a negligible decrease, indicating that the more stable host–guest complexation between Ac-γ-CD and PLGA–TPE forms at 7 : 1. The complex of Ac-γ-CD and PLGA–TPE with a molar ratio 7 : 1 (the precursor solution) was dissolved in aqueous media with a weakly emissive fluorescence, and then copolymerized with acrylamide at room temperature to gain the transparent DN hydrogel, as shown in Fig.…”

“…Previously, similar 1 H NMR spectral changes were also observed for the host–guest complex of γ-CD with TPE based materials. 41…”

“…The determination of the optical properties of the DN hydrogel hydrolyzed by α-amylase were confirmed using previously published literature. 41 The MES buffer solution used consisted of 51 mM NaCl, 5 mM Ca(CH 3 COO) 2 , 1.52 mM NaN 3 , and 100 mM MES with pH 6.0. To study the fluorescence of the α-amylase effect on the DN hydrogel, a series of MES buffer solutions with different α-amylase concentrations (0.5, 1, and 5 U mL −1 ) were prepared, then the DN hydrogel was immersed in α-amylase MES buffer and hydrolyzed for different periods of time at room temperature.…”

Multiregulation of Aggregation‐Induced Emission (AIE) via a Competitive Host–Guest Recognition and α‐Amylase Hydrolyzing

“…This result agrees well with the hydrolysis process of γ ‐CD in the presence of α ‐amylase, in which it needs 200 min to finish the hydrolysis and turn on the fluorescence of TPE. [ 32 ]…”

“…The strong fluorescence of an amphiphilic TPE glycyrrhetinate conjugate was suppressed in the presence of γ ‐CDs. [ 32 ] No doubt, CD based host–guest complexation is a smart way to switch the fluorescence of AIE molecules.…”