ABSTRACT
A urea derivative L1 exhibits Aggregation-Induced Emission (AIE) activity in an acetonitrile-water mixed solvent. The aggregation phenomenon has been corroborated by microscopy and light scattering studies. The ligand (L1) also displays a selective turn-on fluorescence response towards human serum albumin (HSA) in 100% aqueous medium over various other comparable proteins (even bovine serum albumin (BSA)) and enzymes. The weakly emissive probe L1 showed a substantial increase in emission intensity upon binding with HSA through electrostatic interactions. The good linear relationship between the fluorescence enhancement (I/I0 - 1) and the concentration of HSA provided the scope to attain an impressive detection limit as low as 5 µg mL-1. A drug displacement experiment and molecular docking study were employed to ascertain the likely protein (HSA)-ligand binding interactions.
Subject(s)
Fluorescent Dyes/chemistry , Serum Albumin, Human/urine , Urea/analogs & derivatives , Anthracenes/chemical synthesis , Anthracenes/chemistry , Anthracenes/metabolism , Binding Sites , Fluorescence , Fluorescent Dyes/chemical synthesis , Fluorescent Dyes/metabolism , Humans , Limit of Detection , Molecular Docking Simulation , Naphthalenes/chemical synthesis , Naphthalenes/chemistry , Naphthalenes/metabolism , Protein Binding , Serum Albumin, Human/chemistry , Serum Albumin, Human/metabolism , Spectrometry, Fluorescence/methods , Urea/chemical synthesis , Urea/metabolismABSTRACT
Two cyanine-based fluorescent probes, ( E)-2-(4-(diethylamino)-2-hydroxystyryl)-3-ethyl-1,1-dimethyl-1 H-benzo[ e]indol-3-ium iodide (L) and ( E)-3-ethyl-1,1-dimethyl-2-(4-nitrostyryl)-1 H-benzo[ e]indol-3-ium iodide (L1), have been designed and synthesized. Of these two probes, the twisted-intramolecular-charge-transfer (TICT)-based probe, L, can preferentially self-assemble to form nanoaggregates. L displayed a selective turn-on fluorescence response toward human and bovine serum albumin (HSA and BSA) in â¼100% aqueous PBS medium, which is noticeable with the naked eye, whereas L1 failed to sense these albumin proteins. The selective turn-on fluorescence response of L toward HSA and BSA can be attributed to the selective binding of probe L with HSA and BSA without its interfering with known drug-binding sites. The specific binding of L with HSA led to the disassembly of the self-assembled nanoaggregates of L, which was corroborated by dynamic-light-scattering (DLS) and transmission-electron-microscopy (TEM) analysis. Probe L has a limit of detection as low as â¼6.5 nM. The sensing aptitude of probe L to detect HSA in body fluid and an artificial-urine sample has been demonstrated.
Subject(s)
Fluorescent Dyes/chemistry , Serum Albumin/analysis , Animals , Cattle , Dynamic Light Scattering , Humans , Microscopy, Electron, Transmission , Serum Albumin/metabolism , Spectrometry, Fluorescence , Time FactorsABSTRACT
A new water soluble and fluorogenic probe (L) that can demonstrate a specific ratiometric detection of a SO2 derivative (SO32-) in 100% aqueous medium and live cells has been designed and synthesized. The detection process can be visualized by the naked eye, as the orange-red fluorescence of L turns into a strong blue fluorescence upon interaction with SO32-. L displayed several beneficial attributes such as detection in complete aqueous medium, extremely fast response time along with high selectivity and sensitivity. The ratiometric sensing was attributed to the selective nucleophilic addition reaction of SO32- with L. The probe was further used to develop a low cost microfluidic sensor device (µPAD). The probe was biocompatible and its potential to sense SO32- in mitochondria was captured in live HeLa cells.
