Motion‐Induced Changes in Emission as an Effective Strategy for the Ratiometric Probing of Human Serum Albumin and Trypsin in Biological Fluids

Abstract

Herein, we report the formation of a highly luminescent, pH-sensitive, thermoreversible nanoaggregate in pure aqueous medium through the self-agglomeration of carbazole-based amphiphiles. The self-assembly process restricted the intramolecular motion of the molecules and induced a change in its emission signal from blue to cyan, owing to an aggregation-induced emission (AIE) effect. A similar type of ratiometric response was also observed in the presence of human serum albumin (HSA). However, in this case, the molecular motion of the flexible fluorescent probe was restricted by its embedded microenvironment, owing to a motion-induced change in emission (MICE) effect, not by aggregation. Moreover, the probe showed quite high selectivity for HSA over other serum albumin proteins. Our carbazole-based fluorescent probes are a unique example of the ratiometric sensing of HSA through the sole involvement of reversible noncovalent interactions. Considering the important of HSA in clinical diagnosis, a wide range of biological fluids, such as human urine, saliva, and plasma, were screened to analyze their HSA content. In addition, this system was also employed for the detection of trypsin at subnanomolar concentrations through the digestion of HSA.

Switchable Luminescent Probe for Trace-Level Detection of the Spodoptera litura Nuclear Polyhedrosis Virus via a Color-Changing Response

“…On the contrary, the FT-IR spectrum of SLNPV reveals that the stretching frequencies related to the α-helix conformation (amide I band) were found to be affected by the interaction with 1 (Figure S4a). 34 Thus, we can speculate that the charge pairing between 1 and SLNPV might partially modify the 3D structure of the polyhedral protein. Additionally, we have characterized the interaction of compound 1 with SLNPV via circular dichroism (Figure S4b).…”

Detection of biomarkers in body fluids using bioprobes based on aggregation-induced emission fluorogens

“…The selectivity investigation of compound 1 in the presence of various biologically ionic analytes, neutral compounds, and thiol-containing amino acids showed that only HSA induced an increase in fluorescent emission. 21 In 2019, Tu et al designed a series of specific and quantitative tetrazolate-functionalized AIEgens for albumin detection, namely TPE-4TA, (Z)-TPE-2TA, and (E)-TPE-2TA. Fluorescence assay showed that the minimum detectable HSA concentration was in the range of 0.21-0.31 nM.…”

“…It can also serve as a biomarker for many diseases, such as cardiovascular and neurodegenerative diseases. 21 Zhao et al designed fluorescent strips of electrospun fibers for detecting trypsin in urine. Their PSMA-PhB + TPE/Pro strip could provide ratiometric color change when urine trypsin presented.…”

“…Beyond this range, various health issues may be associated with abnormal levels, such as type-2 diabetes or stomatitis. 21 As shown in Fig. 14, the bioprobe compound 1 already mentioned in the urine section can also evaluate albumin in saliva.…”

Addressing Multiple Ions Using Single Optical Probe: Multi‐Color Response via Mutually Independent Sensing Pathways

“…As a continuation of our on‐going endeavor in the field of molecular sensor, herein we have designed an p ‐phenylenevinylene based optical probe with multiple interaction sites (Figure ). Incorporation of ‘mutually exclusive’ responsive units in the same molecule enable us to develop a ‘smart probe’ which can selectively detection of both these metal ions (Cu 2+ and Zn 2+ ) and fluoride simultaneously using incongruous sensing pathways.…”