Selective Binding of Dopamine and Epinephrine in Water by Molecularly Imprinted Fluorescent Receptors

Aggregation-induced emission monomer-based fluorescent molecularly imprinted poly(ionic liquid) synthesized by a one-pot method for sensitively detecting 4-nitrophenol

An aggregation-induced emission monomer-based fluorescent molecularly imprinted poly(ionic liquid) (AIE-FMIPIL) was synthesized for the first time with an AIE probe 4-(1,2,2-triphenylvinyl)phenyl acrylate (TPE), and an ionic liquid as dual functional monomers, and an ionic liquid as cross-linker. AIE-FMIPIL displayed a sphere-like shape and its average diameter was 410 nm. The absolute quantum yields of TPE and AIE-FMIPIL were 9.23% and 12.61%, respectively. The synergetic effect of TPE in the AIE-FMIPIL framework contributed to the higher quantum yield of AIE-FMIPIL. 4-Nitrophenol (4-NP) efficiently quenched AIE-FMIPIL with high fluorescence based on the Förster resonance energy transfer mechanism. The synthesized AIE-FMIPIL sensor was highly sensitive for 4-NP detection (linear range, 0.02-1.5 μM) in the optimal detection condition, with a low detection limit of 10 nM (S/N = 3). AIE-FMIPIL showed increased sensitivity and quenching efficiency compared with AIE-FMIP comprising a traditional monomer and cross-linker. AIE-FMIPIL exhibited selective binding to 4-NP because of the imprinted sites. AIE-FMIPIL was adopted to detect 4-NP in environmental samples.

Substrate Protection in Controlled Enzymatic Transformation of Peptides and Proteins

Proteins are involved in practically every single biological process. The many enzymes involved in their synthesis, cleavage, and posttranslational modification (PTM) carry out highly specific tasks with no usage of protecting groups. Yet, the chemists' strategy of protection/deprotection potentially can be highly useful, for example, when a specific biochemical reaction catalyzed by a broad-specificity enzyme needs to be inhibited, during infection of cells by enveloped viruses, in the invasion and spread of cancer cells, and upon mechanistic investigation of signal-transduction pathways. Doing so requires highly specific binding of peptide substrates in aqueous solution with biologically competitive affinities. Recent development of peptide-imprinted cross-linked micelles allows such protection and affords previously impossible ways of manipulating peptides and proteins in enzymatic transformations.

A simple approach to prepare fluorescent molecularly imprinted nanoparticles

Fluorescent molecularly imprinted polymers (FMIPs) are gaining increasing attention in analytical and medical sciences, particularly silica-based FMIPs due to their low cost, environmentally friendly nature and good biocompatibility. However, at present, silica-based FMIPs are usually prepared through several steps and displayed low selectivity. Here, a simple approach was utilized for preparing silica-based FMIP nanoparticles. The polymerization was initiated by 3-aminopropyltriethoxysilane (APTES), which also acted as the functional monomer in the imprinting system; in addition, to achieve one-pot synthesis, a fluorescent monomer was prepared by a simple reaction between fluorescein isothiocyanate (FITC) and APTES. The as-synthesized FMIP nanoparticles displayed high specificity and fast response time (<1 min) towards the target molecule. Environmental pH and buffer salt could affect the specific recognition behaviors of the FMIP nanoparticles. Such a simple catalyst-free synthetic technique could also be employed for the preparation of FMIP nanoparticles targeting other acidic molecules.