TY - JOUR A1 - Wan, Wei A1 - Biyikal, Mustafa A1 - Wagner, R. A1 - Sellergren, B. A1 - Rurack, Knut T1 - Fluorescent sensorymicroparticles that 'light-up' consisting of a silica core and a molecularly imprinted polymer (MIP) shell N2 - From darkness came light: Incorporation of urea-based fluorescent dyes in an anion-imprinted thin polymer shell coated onto silica microparticles leads to a unique and highly enantioselective fluorescent 'light-up' response to analytes (see scheme, MIP molecularly imprinted polymer). KW - Core–shell particles KW - Enantioselectivity KW - Fluorescence KW - Molecularly imprinted polymers KW - Sensors PY - 2013 U6 - https://doi.org/10.1002/anie.201300322 SN - 1433-7851 SN - 1521-3773 SN - 0570-0833 VL - 52 IS - 27 SP - 7023 EP - 7027 PB - Wiley-VCH CY - Weinheim AN - OPUS4-28740 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Wagner, R. A1 - Wan, Wei A1 - Biyikal, Mustafa A1 - Benito-Pena, E. A1 - Moreno-Bondi, M.C. A1 - Lazraq, I. A1 - Rurack, Knut A1 - Sellergren, B. T1 - Synthesis, spectroscopic, and analyte-responsive behavior of a polymerizable naphthalimide-based carboxylate probe and molecularly imprinted polymers prepared thereof N2 - A naphthalimide-based fluorescent indicator monomer 1 for the integration into chromo- and fluorogenic molecularly imprinted polymers (MIPs) was synthesized and characterized. The monomer was equipped with a urea binding site to respond to carboxylate-containing guests with absorption and fluorescence changes, namely a bathochromic shift in absorption and fluorescence quenching. Detailed spectroscopic analyses of the title compound and various models revealed the signaling mechanism. Titration studies employing benzoate and Z-ʟ-phenylalanine (Z-ʟ-Phe) suggest that indicator monomers such as the title compound undergo a mixture of deprotonation and complex formation in the presence of benzoate but yield hydrogen-bonded complexes, which are desirable for the molecular imprinting process, with weakly basic guests like Z-ʟ-Phe. Compound 1 could be successfully employed in the synthesis of monolithic and thin-film MIPs against Z-ʟ-Phe, Z-L-glutamic acid, and penicillin G. Chromatographic assessment of the selectivity features of the monoliths revealed enantioselective discrimination and clear imprinting effects. Immobilized on glass coverslips, the thin-film MIPs of 1 displayed a clear signaling behavior with a pronounced enantioselective fluorescence quenching dependence and a promising discrimination against cross-analytes. KW - Aminosäuren KW - Enantioselektivität KW - Fluoreszenz KW - Molekular geprägte polymere KW - Sensorfilme PY - 2013 U6 - https://doi.org/10.1021/jo3019522 SN - 0022-3263 SN - 1520-6904 VL - 78 IS - 4 SP - 1377 EP - 1389 PB - American Chemical Society CY - Washington, DC AN - OPUS4-27741 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Zhu, Shengchao A1 - Fischer, Tobias A1 - Wan, Wei A1 - Descalzo López, Ana Belén A1 - Rurack, Knut T1 - Luminescence amplification strategies integrated with microparticle and nanoparticle platforms N2 - The amplification of luminescence signals is often the key to sensitive and powerful detection protocols. Besides optimized fluorescent probes and labels, functionalized nano- and microparticles have received strongly increasing attention in this context during the past decade. This contribution introduces the main signalling concepts for particle-based amplification strategies and stresses, especially the important role that metal and semiconductor nanoparticles play in this field. Besides resonance energy transfer, metal-enhanced emission and the catalytic generation of luminescence, the impact of multi-chromophoric objects such as dye nanocrystals, dendrimers, conjugated polymers or mesoporous hybrid materials is assessed. The representative examples discussed cover a broad range of analytes from metal ions and small organic molecules to oligonucleotides and enzyme activity. KW - Luminescence KW - Multi-chromosphore systems KW - Nanoparticles KW - Resonance energy transfer KW - Signal amplification PY - 2011 U6 - https://doi.org/10.1007/128_2010_99 SN - 0340-1022 SN - 1436-5049 VL - 300 SP - 51 EP - 91 PB - Springer CY - Berlin ; Heidelberg [u.a.] AN - OPUS4-23633 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Wagner, Sabine A1 - Zapata, Carlos A1 - Wan, Wei A1 - Gawlitza, Kornelia A1 - Weber, M. A1 - Rurack, Knut T1 - Role of Counterions in Molecularly Imprinted Polymers for Anionic Species N2 - Small-molecule oxoanions are often imprinted noncovalently as carboxylates into molecularly imprinted polymers (MIPs), requiring the use of an organic counterion. Popular species are either pentamethylpiperidine (PMP) as a protonatable cation or tetraalkylammonium (TXA) ions as permanent cations. The present work explores the influence of the TXA as a function of their alkyl chain length, from methyl to octyl, using UV/vis absorption, fluorescence titrations, and HPLC as well as MD simulations. Protected phenylalanines (Z-L/D-Phe) served as templates/analytes. While the influence of the counterion on the complex stability constants and anion-induced spectral changes shows a monotonous trend with increasing alkyl chain length at the prepolymerization stage, the cross-imprinting/rebinding studies showed a unique pattern that suggested the presence of adaptive cavities in the MIP matrix, related to the concept of induced fit of enzyme−substrate interaction. Larger cavities formed in the presence of larger counterions can take up pairs of Z-X-Phe and smaller TXA, eventually escaping spectroscopic detection. Correlation of the experimental data with the MD simulations revealed that counterion mobility, the relative distances between the three partners, and the hydrogen bond lifetimes are more decisive for the response features observed than actual distances between interacting atoms in a complex or the orientation of binding moieties. TBA has been found to yield the highest imprinting factor, also showing a unique dual behavior regarding the interaction with template and fluorescent monomer. Finally, interesting differences between both enantiomers have been observed in both theory and experiment, suggesting true control of enantioselectivity. The contribution concludes with suggestions for translating the findings into actual MIP development. KW - Anion receptors KW - Fluorescence sensing KW - Molecular dynamics simulations KW - Molecularly imprinted polymers KW - Rational design PY - 2018 U6 - https://doi.org/10.1021/acs.langmuir.8b00500 SN - 0743-7463 VL - 34 IS - 23 SP - 6963 EP - 6975 PB - American Chemical Society CY - Washington, D.C. AN - OPUS4-45399 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Li, Q. A1 - Shinde, S. A1 - Grasso, G. A1 - Caroli, A. A1 - Abouhany, R. A1 - Lanzillotta, M. A1 - Pan, G. A1 - Wan, Wei A1 - Rurack, Knut A1 - Sellergren, B. T1 - Selective detection of phospholipids using molecularly imprinted fluorescent sensory core-shell particles N2 - Sphingosine-1-phosphate (S1P) is a bioactive sphingo-lipid with a broad range of activities coupled to its role in G-protein coupled receptor signalling. Monitoring of both intra and extra cellular levels of this lipid is challenging due to its low abundance and lack of robust affinity assays or sensors. We here report on fluorescent sensory core-shell molecularly imprinted polymer (MIP) particles responsive to near physiologically relevant levels of S1P and the S1P receptor modulator fingolimod phosphate (FP) in spiked human serum samples. Imprinting was achieved using the tetrabutylammonium (TBA) salt of FP or phosphatidic acid (DPPA·Na) as templates in combination with a polymerizable nitrobenzoxadiazole (NBD)-urea monomer with the dual role of capturing the phospho-anion and signalling its presence. The monomers were grafted from ca 300 nm RAFT-modified silica core particles using ethyleneglycol dimethacrylate (EGDMA) as crosslinker resulting in 10–20 nm thick shells displaying selective fluorescence response to the targeted lipids S1P and DPPA in aqueous buffered media. Potential use of the sensory particles for monitoring S1P in serum was demonstrated on spiked serum samples, proving a linear range of 18–60 μM and a detection limit of 5.6 μM, a value in the same range as the plasma concentration of the biomarker. KW - Molecularly imprinted polymers KW - Phospholipids KW - Fluorescence KW - Dye monomers PY - 2020 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:b43-509485 SN - 2045-2322 VL - 10 IS - 1 SP - 9924 PB - Nature Research CY - London AN - OPUS4-50948 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Shinde, S. A1 - El-Schich, Z. A1 - Malakpour, A. A1 - Wan, Wei A1 - Dizeyi, N. A1 - Mohammadi, R. A1 - Rurack, Knut A1 - Gjörloff Wingren, A. A1 - Sellergren, B. T1 - Sialic acid-imprinted fluorescent core-shell particles for selective labeling of cell surface glycans N2 - The expression of cell surface glycans terminating with sialic acid (SA) residues has been found to correlate with various disease states there among cancer. We here report a novel strategy for specific fluorescence labeling of such motifs. This is based on sialic acid-imprinted core–shell nanoparticles equipped with nitrobenzoxadiazole (NBD) fluorescent reporter groups allowing environmentally sensitive fluorescence detection at convenient excitation and emission wavelengths. Imprinting was achieved exploiting a hybrid approach combining reversible boronate ester formation between p-vinylphenylboronic acid and SA, the introduction of cationic amine functionalities, and the use of an NBD-appended urea-monomer as a binary hydrogen-bond donor targeting the SA carboxylic acid and OH functionalities. The monomers were grafted from 200 nm RAFT-modified silica core particles using ethylene glycol dimethacrylate (EGDMA) as cross-linker resulting in a shell thickness of ca. 10 nm. The particles displayed strong affinity for SA in methanol/water mixtures (K = 6.6 × 105 M-1 in 2% water, 5.9 × 103 M-1 in 98% water, Bmax ≈ 10 µmol g-1), whereas binding of the competitor glucuronic acid (GA) and other monosaccharides was considerably weaker (K (GA) = 1.8 × 103 M-1 in 98% water). In cell imaging experiments, the particles selectively stained different cell lines in correlation with the SA expression level. This was further verified by enzymatic cleavage of SA and by staining using a FITC labeled SA selective lectin. KW - Glycoproteine KW - Biomarker KW - Fluoreszenz KW - Polymere KW - Krebsdiagnostik PY - 2015 U6 - https://doi.org/10.1021/jacs.5b08482 SN - 0002-7863 SN - 1520-5126 VL - 137 IS - 43 SP - 13908 EP - 13912 PB - American Chemical Society CY - Washington, DC, USA AN - OPUS4-35227 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Wan, Wei A1 - Wagner, Sabine A1 - Rurack, Knut T1 - Fluorescent monomers: "bricks" that make a molecularly imprinted polymer "bright" N2 - Molecularly imprinted polymers (MIPs) are potent and established recognition phases in separation and enrichment applications. Because of their robustness, versatility and format adaptability, they also constitute very promising sensing phases, especially when the active sensing element is directly integrated into the MIP. Fluorescent MIPs incorporating fluorescent monomers are perhaps the best developed and most successful approach here. This article reviews the state of the art in this field, discussing the pros and cons of the use of fluorescent dye and probe derivatives as such monomers, the different molecular interaction forces for template complexation, signalling modes and a variety of related approaches that have been realized over the years, including Förster resonance energy transfer processes, covalent imprinting, postmodification attachment of fluorescent units and conjugated polymers as MIPs; other measurement schemes and sensing chemistries that use MIPs and fluorescence interrogation to solve analytical problems (fluorescent competitive assays, fluorescent analytes, etc.) are not covered here. Throughout the article, photophysical processes are discussed to facilitate understanding of the effects that can occur when one is planning for a fluorescence response to happen in a constrained polymer matrix. The article concludes with a concise assessment of the suitability of the different formats for sensor realization. KW - Chemical sensors KW - Fluorescence KW - Molecularly imprinted polymers KW - Dyes KW - Sol-gel PY - 2016 U6 - https://doi.org/10.1007/s00216-015-9174-4 SN - 1618-2642 SN - 1618-2650 VL - 408 IS - 7 SP - 1753 EP - 1771 PB - Springer CY - Berlin AN - OPUS4-35830 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Costa, Elena A1 - Climent Terol, Estela A1 - Gawlitza, Kornelia A1 - Wan, Wei A1 - Weller, Michael G. A1 - Rurack, Knut T1 - Optimization of analytical assay performance of antibody-gated indicator-releasing mesoporous silica particles N2 - Antibody-gated indicator delivery (gAID) systems based on mesoporous silica nano- and microparticle scaffolds are a promising class of materials for the sensitive chemical detection of small-molecule analytes in simple test formats such as lateral flow assays (LFAs) or microfluidic chips. Their architecture is reminiscent of drug delivery systems, only that reporter molecules instead of drugs are stored in the voids of a porous host particle. In addition, the pores are closed with macromolecular “caps” through a tailored “gatekeeping” recognition chemistry so that the caps are opened when an analyte has reacted with a “gatekeeper”. The subsequent uncapping leads to a release of a large number of indicator molecules, endowing the system with signal amplification features. Particular benefits of such systems are their modularity and adaptability. With the example of the immunochemical detection of type-I pyrethroids by fluorescent dye-releasing gAID systems, the influence of several tuning modes on the optimisation of such hybrid sensory materials is introduced here. In particular, different mesoporous silica supports (from nano- and microparticles to platelets and short fibres), different functionalisation routes and different loading sequences were assessed. The materials’ performances were evaluated by studying their temporal response behaviour and detection sensitivity, including the tightness of pore closure (through the amount of blank release in the absence of analyte) and the release kinetics. Our results indicate that the better the paratope-accommodating Fab region of the antibody “cap” fits into the host material's pore opening, the better the closing/opening mechanism can be controlled. Because such materials are well-suited for LFAs, performance assessment included a test-strip format besides conventional assays in suspension. In combination with dyes as indicators and smartphones for read-out, simple analytical tests for use by untrained personnel directly at a point-of-need such as an aeroplane cabin can be devised, allowing for sensitivities down to the μg kg−1 range in <5 min with case-required selectivities. KW - Antibody-gated indicator delivery KW - Lateral flow assay KW - SBA-15 KW - SBA-16 KW - Type-I pyrethroids KW - Phenothrin KW - Permethrin KW - Etofenprox KW - Amplification KW - Biosensors KW - Immunoassays KW - Mesoporous particles KW - Optical detection PY - 2020 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:b43-517053 VL - 8 IS - 22 SP - 4950 EP - 4961 PB - Royal Society of Chemistry AN - OPUS4-51705 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Wan, Wei A1 - Descalzo, Ana B. A1 - Shinde, S. A1 - Weißhoff, Hardy A1 - Orellana, G. A1 - Sellergren, B. A1 - Rurack, Knut T1 - Ratiometric fluorescence detection of phosphorylated amino acids through excited-state proton transfer by using molecularly imprinted polymer (MIP) recognition nanolayers N2 - 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 (Kb>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 crosslinker 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 comonomers 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. KW - Core-shell particles KW - Excited-state proton transfer KW - Fluorescence KW - Molecular imprinting KW - Phosphorylated amino acids PY - 2017 U6 - https://doi.org/10.1002/chem.201703041 SN - 1521-3765 SN - 0947-6539 VL - 23 IS - 63 SP - 15974 EP - 15983 PB - Wiley-VCH CY - Weinheim AN - OPUS4-43101 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Burnage, Samual A1 - Bell, Jérémy A1 - Wan, Wei A1 - Kislenko, Evgeniia A1 - Rurack, Knut T1 - Combining a hybrid chip and tube microfluidic system with fluorescent molecularly imprinted polymer (MIP) core–shell particles for the derivatisation, extraction, and detection of peptides with N-terminating phosphorylated tyrosine N2 - The reliable identification and quantitation of phosphorylated amino acids, peptides and proteins is one of the key challenges in contemporary bioanalytical research, an area of particular interest when attempting to diagnose and treat diseases at an early stage. We have developed a synthetic probe for targeting phosphorylated amino acids, based on core–shell submicron-sized particles consisting of a silica core, coated with a molecularly imprinted polymer (MIP) shell. The MIP layer contains a fluorescent probe crosslinker which binds selectively to phosphorylated tyrosine (pY) moieties with a significant imprinting factor (IF) and responds with a "light-up” fluorescence signal. The bead-based ratiometric detection scheme has been successfully transferred to a microfluidic chip format and its applicability to rapid assays has been exemplarily shown by discriminating a pY-terminating oligopeptide against its nonphosphorylated counterpart. Such miniaturised devices could lead to an automated pY or pY N-terminated peptide measurement system in the future. The setup combines a modular microfluidic system for amino acid derivatisation, extraction (by micropillar co-flow) and selective adsorption and detection with the fluorescent MIP core–shell particle probes. A miniaturised optical assembly for low-light fluorescence measurements was also developed, based on miniaturised opto-electronic parts and optical fibres. The emission from the MIP particles upon binding of pY or pY N-terminated peptides could be monitored in real-time. KW - Microfluidics KW - Molecularly imprinted polymers KW - Phosphorylated peptides KW - Fluorescence KW - Core-shell particles PY - 2022 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:b43-569204 SN - 1473-0197 VL - 23 IS - 3 SP - 466 EP - 474 PB - Royal Society of Chemistry CY - Cambridge AN - OPUS4-56920 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER -