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Ratiometric Fluorescence Detection of Phosphorylated Amino Acids Through Excited‐State Proton Transfer by Using Molecularly Imprinted Polymer (MIP) Recognition Nanolayers
Author(s) -
Wan Wei,
Descalzo Ana B.,
Shinde Sudhirkumar,
Weißhoff Hardy,
Orellana Guillermo,
Sellergren Börje,
Rurack Knut
Publication year - 2017
Publication title -
chemistry – a european journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.687
H-Index - 242
eISSN - 1521-3765
pISSN - 0947-6539
DOI - 10.1002/chem.201703041
Subject(s) - molecularly imprinted polymer , molecular imprinting , monomer , analyte , fluorescence , chemistry , polymer , photochemistry , mesoporous silica , methacrylamide , combinatorial chemistry , selectivity , polymer chemistry , mesoporous material , chromatography , organic chemistry , acrylamide , physics , quantum mechanics , catalysis
A 2,3‐diaminophenazine bis‐urea fluorescent probe monomer ( 1 ) was developed. It responds to phenylphosphate and phosphorylated amino acids in a ratiometric fashion with enhanced fluorescence accompanied by the development of a redshifted emission band arising from an excited‐state proton transfer (ESPT) process in the hydrogen‐bonded probe/analyte complex. The two urea groups of 1 form a cleft‐like binding pocket ( K b >10 10 L 2 mol −2 for 1:2 complex). Imprinting of 1 in presence of ethyl ester‐ and fluorenylmethyloxycarbonyl (Fmoc)‐protected phosphorylated tyrosine (Fmoc‐pTyr‐OEt) as the template, methacrylamide as co‐monomer, and ethyleneglycol dimethacrylate as cross‐linker gave few‐nanometer‐thick molecularly imprinted polymer (MIP) shells on silica core microparticles with excellent selectivity for the template in a buffered biphasic assay. The supramolecular recognition features were established by spectroscopic and NMR studies. Rational screening of co‐monomers and cross‐linkers allowed to single out the best performing MIP components, giving significant imprinting factors (IF>3.5) while retaining ESPT emission and the ratiometric response in the thin polymer shell. Combination of the bead‐based detection scheme with the phase‐transfer assay dramatically improved the IF to 15.9, allowing sensitive determination of the analyte directly in aqueous media.