5. Optical Ion Sensors
This is a long standing project that aims to develop optical sensing principles for the detection of ionic species. Original film-based optode approaches were gradually replaced with micrometer-sized sensing particles and eventually with emulsified nanosensors. The optical reporter principle shifted from lipophilic pH indicators to ionic solvatochromic dyes, both of a hydrophilic and lipophilic nature. Emulsification allows one to achieve highly efficient mass transport characteristics, giving rise to so-called exhaustive sensing. It also forms the basis for highly selective ion titration principles based on extraction principles that complement or replace established complexometric titrations.
Publications:
(396) Optical Detection of Heparin in Whole Blood Samples using Nanosensors Embedded in an Agarose Hydrogel , Nussbaum, R.; Robinson, K. J.; Soda, Y.; Bakker, E. in preparation.
(385) Recent improvements to the selectivity of extraction-based optical ion sensors , Robinson, K. J.; Soda, Y.; Bakker, E. Chem. Commun., 2022, 58, 4279-4287. DOI: 10.1039/d1cc06636f (open access).
(378) Surfactants for Optode Emulsion Stabilization Without Sacrificing Selectivity or Binding Constants, Robinson, K. J.; Mao, C.; Bakker, E. Anal. Chem., 2021, 93, 15941–15948. DOI: 10.1021/acs.analchem.1c03232.
(377) Protamine/Heparin Optical Nanosensor based on Solvatochromism, Soda, Y.; Robinson, K.; Nussbaum, R.; Bakker, E. Chem. Sci, 2021, 12, 15596-15602. DOI: 10.1039/D1SC04930E (open access).
(367) Colorimetric ratiometry with ion optodes for spatially resolved concentration analysis, Soda, Y.; Bakker, E. Anal. Chim. Acta, 2021, 1154, 338225. DOI: 10.1016/j.aca.2021.338225 (open access).
(349) Optical Sensing with a Potentiometric Sensing Array by Prussian Blue Film Integrated Closed Bipolar Electrodes, Jansod, S.; Cherubini, T.; Soda, Y.; Bakker, E. Anal. Chem., 2020, 92, 9138–9145. DOI: 10.1021/acs.analchem.0c01421 (open access).
(343) Tunable detection range of ion-selective nano-optodes by controlling solvatochromic dye transducer lipophilicity, Wang, L.; Bakker, E. Chem. Commun., 2019, 55, 12539-12542. DOI: 10.1039/C9CC06729A (open access).
(335) Simplified Fabrication for Ion-Selective Optical Emulsion Sensor with Hydrophobic Solvatochromic Dye Transducer: A Cautionary Tale, Wang, L.; Sadler, S.; Cao, T.; Xie, X.; Bakker, E. Anal. Chem., 2019, 91, 8973-8978. DOI: 10.1021/acs.analchem.9b01145 (open access).
(295) Reversible pH-independent optical potassium sensor with lipophilic solvatochromic dye transducer on surface modified microporous nylon, Wang, L.; Xie, X.; Zhai, Z.; Bakker, E. Chem. Commun., 2016, 52, 14254 - 14257. DOI: 10.1039/C6CC07841A.
(279) Ion-Selective Optical Nanosensors based on Solvatochromic Dyes with Different Lipophilicity: From Bulk Partitioning to Interfacial Accumulation, Xie, X.; Szilagyi, I.; Zhai, J.; Wang, L.; Bakker, E. ACS Sensors, 2016, 1, 516–520. DOI: 10.1021/acssensors.6b00006 (open access).
(261) Potassium Sensitive Optical Nanosensors Containing Voltage Sensitive Dyes, Xie, X.; Gutierrez, A.; Trofimov, V.; Szilágyi, I.; Soldati, T.; Bakker, E. Chimia, 2015, 69, 196-198. DOI: 10.2533/chimia.2015.196 (open access).
(255) Ion-Selective Optode Nanospheres as Heterogeneous Indicator Reagents in Complexometric Titrations, Zhai, J.; Xie, X.; Bakker, E. Anal. Chem., 2015, 87, 2827–2831. DOI: 10.1021/ac504213q.
(253) Ion Selective Optodes: From the Bulk to the Nanoscale, Xie, X.; Zhai, J.; Bakker, E. Anal. Bioanal. Chem., 2015, 407, 3899-3910. DOI: 10.1007/s00216-014-8413-4.
(251) Titration-free buffer capacity sensor using a dynamic optode based on hydrogel-incorporated photochromic spiropyran, Mistlberger, G.; Pawlak, M.; Bakker, E.; Klimant, I. Chem. Commun., 2015, 51, 4172-4175. DOI: 10.1039/C4CC07821G.
(238) Ionophore based Ion-Selective Optical NanoSensors Operating in Exhaustive Sensing Mode, Xie, X.; Zhai, J.; Crespo, G. A.; Bakker, E. Anal. Chem., 2014, 86, 8770–8775. DOI: 10.1021/ac5019606 (open access).
(235) Potassium-Selective Optical Microsensors Based On Surface Modified Polystyrene Microspheres, Xie, X.; Crespo, G. A.; Zhai, J.; Szilagyi, I.; Bakker, E. Chem. Commun., 2014, 50, 4592-4595. DOI: 10.1039/C4CC01313A.
(230) pH Independent Nano-Optodes Based on Exhaustive Ion-Selective Nanospheres, Xie, X.; Zhai, J.; Bakker, E. Anal. Chem., 2014, 86, 2853–2856. DOI: 10.1021/ac403996s.
(224) Ionophore-Based Optical Sensors, Mistlberger, G.; Crespo, G.A.; Bakker, E. Ann. Rev. Anal. Chem., 2014, 7, 483-512. DOI: 10.1146/annurev-anchem-071213-020307.
(215) Oxazinoindolines as Fluorescent H+ Turn-On Chromoionophores For Optical and Electrochemical Ion Sensors, Xie, X.; Crespo, G. A.; Bakker, E. Anal. Chem., 2013, 85, 7434–7440. DOI: 10.1021/ac401367b (open access).
(208) Photoresponsive Ion Extraction/Release Systems: Dynamic Ion Optodes for Calcium and Sodium Based on Photochromic Spiropyran, Mistlberger, G.; Xie, X.; Pawlak, M.; Crespo, G.; Bakker, E. Anal. Chem., 2013, 85, 2983-2990. DOI: 10.1021/ac4000283.
(199) Ionophore-Based Ion Optodes without a Reference Ion: Electrogenerated Chemiluminescence for Potentiometric Sensors, Crespo, G.A.; Bakker, E. Analyst, 2012, 137, 4988-4994. DOI: 10.1039/C2AN35516G.
(193) Direct Optical Carbon Dioxide Sensing Based on a Polymeric Sensing Film Doped with a Selective Molecular Tweezer Type Ionophore, Xie, X.; Tercier-Waeber, M.; Pawlak, M.; Bakker, E. Anal. Chem., 2012, 84, 3163-3169. DOI: 10.1021/ac2030046 (open access).
(187) Advancing Membrane Electrodes and Optical Ion Sensors, Bakker, E.; Crespo, G.; Grygolowicz-Pawlak, E.; Mistlberger, G.; Pawlak, M.; Xie, X. Chimia, 2011, 65, 141-149. DOI: 10.2533/chimia.2011.141.
(148) Multiplexed Flow Cytometric Sensing of Blood Electrolytes in Physiological Samples Using Fluorescent Bulk Optode Microspheres, Xu, C.; Wygladacz, K.; Retter, R.; Bell, M.; Bakker, E. Anal. Chem., 2007, 79, 9505-9512. DOI: 10.1021/ac7016212.
(147) Absorbance Characterization of Microsphere-Based Ion-Selective Optodes, Ye, N.; Wygladacz, K.; Bakker, E. Anal. Chim. Acta, 2007, 596, 195-200. DOI: 10.1016/j.aca.2007.06.015.
(146) Polymerized Nile Blue Derivatives for Plasticizer-Free Fluorescent Bulk Optode Ion Sensors, Ngeontae, W.; Xu, C.; Ye, N.; Wygladacz, K.; Aeungmaitepirom, W.; Tuntulani, T.; Bakker, E. Anal. Chim. Acta, 2007, 599, 124-133. DOI: 10.1016/j.aca.2007.07.058.
(144) Multicolor Quantum-dot Encoding for Polymeric Particle-Based Optical Ion Sensors, Xu, C.; Bakker, E. Anal. Chem., 2007, 79, 3716-3723. DOI: 10.1021/ac0701233.
(141) Fluorescent microsphere fiber optic microsensor array for direct iodide detection at low picomolar concentrations, Wygladacz, K.; Bakker, E. Analyst, 2007, 132, 268-272. DOI: 10.1039/B614562K.
(132) Novel potentiometric and optical Ag+-selective sensors with subnanomolar detection limits, Szigeti, Z.; Malon, A.; Vigassy, T.; Csokai, V.; Grün, A.; Wygladacz, K.; Yu, N.; Bitter, R.; Bakker, E.; Pretsch, E. Anal. Chim. Acta, 2006, 572, 1-10. DOI: 10.1016/j.aca.2006.05.009.
(126) Fiber Optic Microsensor Array Based on Fluorescent Bulk Optode Microspheres for the Trace Analysis of Silver Ions, Wygladacz, K.; Radu, A.; Xu, C.; Qin, Y.; Bakker, E. Anal. Chem., 2005, 77, 4706-4712. DOI: 10.1021/ac050856s.
(122) Microsphere Optical Ion Sensors Based On Doped Silica Templates, Xu, C.; Wygladacz, K.; Qin, Y.; Retter, R.; Bell, M.; Bakker, E. Anal. Chim. Acta, 2005, 537, 135-143. DOI: 10.1016/j.aca.2005.01.008.
(119) Shifting the measuring range of chloride selective electrodes and optodes based on the anticrown ionophore [9]mercuracarborand-3 by the addition of 1-decanethiol, Radu, A.; Bakker, E. Chem. Anal., 2005, 50, 71-83. DOI: .
(118) Imaging Fiber Microarray Fluorescent Ion Sensors Based on Bulk Optode Microspheres , Wygladacz, K.; Bakker, E. Anal. Chim. Acta, 2005, 532, 61-69. DOI: 10.1016/j.aca.2004.10.071.
(111) Optical Determination of Ionophore Diffusion Coefficients in Plasticized Poly(Vinyl Chloride) Sensing Films, Long, R.; Bakker, E. Anal. Chim. Acta, 2004, 511, 91-95. DOI: 10.1016/j.aca.2004.01.028.
(109) Optical Chloride Sensor based on [9]Mercuracarborand-3 with Massively Expanded Measuring Range, Xu, C.; Qin, Y.; Bakker, E. Talanta, 2004, 63, 180-184. DOI: 10.1021/ac026055w.
(105) Rotating Electrode Potentiometry for Inner Solution Optimization of Low-Detection-Limit Ion-Selective Electrodes, Radu, A.; Telting-Diaz, M.; Bakker, E. Anal. Chem., 2003, 75, 6922-6931. DOI: 10.1021/ac0346961.
(97) Mechanistic Insights into the Development of Highly Selective Optical Chloride Sensors Based on the [9]Mercuracarborand-3 Ionophore, Ceresa, A.; Qin, Y.; Peper, S.; Bakker, E. Anal. Chem., 2003, 75, 133-140. DOI: 10.1021/ac026055w.
(95) Plasticizer-Free Polymer Containing a Covalently Immobilized Ca2+-Selective Ionophore for Potentiometric and Optical Sensors, Qin, Y.; Peper, S.; Radu, A.; Ceresa, A.; Bakker, E. Anal. Chem., 2003, 75, 3038-3045. DOI: 10.1021/ac0263059.
(68) Spatial and Spectral Imaging of Single Micron-Sized Solvent Cast Fluorescent Plasticized Poly(vinyl chloride) Optode Particles, Tsagkatakis, I.; Peper, S.; Bakker, E. Anal. Chem., 2001, 73, 315-320. DOI: 10.1021/ac000832f.
(67) Cross-linked dodecyl acrylate microspheres: novel matrices for plasticizer-free optical ion sensing, Peper, S.; Tsagkatakis, I.; Bakker, E. Anal. Chim. Acta, 2001, 442, 25-33. DOI: 10.1016/S0003-2670(01)01132-1.
(42) Carrier-Based Ion-Selective Electrodes and Bulk Optodes. 2. Ionophores Applied in Potentiometric and Optical Sensors, Bühlmann, P.; Pretsch, E.; Bakker, E. Chem. Rev., 1998, 98, 1593-1687. DOI: 10.1021/cr970113+.
(41) Spectroscopic in-situ Imaging of Acid Coextraction Processes in Solvent Polymeric Ion-Selective Electrode and Optode Membranes, Lindner, E.; Zwickl, T.; Bakker, E.; Lan, B.T.T.; Toth, K.; Pretsch, E. Anal. Chem., 1998, 70, 1176-1181. DOI: 10.1021/ac970952w.
(36) Carrier-Based Ion-Selective Electrodes and Bulk Optodes. 1. General Characteristics, Bakker, E.; Bühlmann, P.; Pretsch, E. Chem. Rev., 1997, 97, 3083-3132. DOI: 10.1021/cr940394a.
(32) Selectivity Comparison of Neutral Carrier-Based Ion-Selective Optical and Potentiometric Sensing Schemes, Bakker, E. Anal. Chim. Acta, 1997, 350, 329-340. DOI: 10.1016/S0003-2670(97)00218-3.
(27) Miniature Sodium-Selective Optode with Fluorescent pH Chromoionophores and Tunable Dynamic Range, Shortreed, M.R.; Bakker, E.; Kopelman, R. Anal. Chem., 1996, 68, 2656-2662. DOI: 10.1021/ac960035a.
(21) Lipophilicity of Tetraphenylborate Derivatives as Anionic Sites in Neutral Carrier-Based Solvent Polymeric Membranes and Lifetime of Corresponding Ion-Selective Electrochemical and Optical Sensors, Bakker, E.; Pretsch, E. Anal. Chim. Acta, 1995, 309, 7-17. DOI: 10.1016/0003-2670(95)00077-D.
(16) Optimum Composition of Neutral Carrier Based pH Electrodes, Bakker, E.; Xu, A.; Pretsch, E. Anal. Chim. Acta, 1994, 295, 253-262. DOI: 10.1016/0003-2670(94)80230-0.
(9) Detection Limit of Ion-Selective Bulk Optodes and Corresponding Electrodes, Bakker, E.; Willer, M.; Pretsch, E. Anal. Chim. Acta, 1993, 282, 265-271. DOI: 10.1016/0003-2670(93)80210-C.
(7) Synthesis and Characterization of Neutral Hydrogen Ion-Selective Chromoionophores for Use in Bulk Optodes, Bakker, E.; Lerchi, M.; Rosatzin, T.; Rusterholz, B.; Simon, W. Anal. Chim. Acta, 1993, 278, 211-225. DOI: 10.1016/0003-2670(93)85102-P.
(6) Optodes in Clinical Chemistry: Potential and Limitations, Spichiger, U.E.; Freiner, D.; Bakker, E.; Rosatzin, T.; Simon, W. Sens. Actuators, B, 1993, 11, 263-271. DOI: 10.1016/0925-4005(93)85264-B.
(5) Optical Sensors Based on Neutral Carriers, Spichiger, U.E.; Simon, W.; Bakker, E.; Lerchi, M.; Bühlmann, P.; Haug, J.-P.; Kuratli, M.; Osawa, S.; West, S. Sens. Actuators, B, 1993, 11, 1-8. DOI: 10.1016/0925-4005(93)85232-Y.
(4) Chemically Selective Optode Membranes and Optical Detection Modes, Spichiger, U.E.; Freiner, D.; Lerchi, M.; Bakker, E.; Dohner, R.; Simon, W. SPIE, 1992, 1796, 371-382. DOI: .
(3) Selectivity of Ion-Sensitive Bulk Optodes, Bakker, E.; Simon, W. Anal. Chem., 1992, 64, 1805-1812. DOI: 10.1021/ac00041a012.
(2) Lead-Selective Bulk Optodes Based on Neutral Ionophores with Subnanomolar Detection Limits, Lerchi, M.; Bakker, E.; Rusterholz, R.; Simon, W. Anal. Chem., 1992, 64, 1534-1540. DOI: 10.1021/ac00038a007.
(1) Characterization of Sodium-Selective Optode Membranes Based on Neutral Ionophores and Assay of Sodium in Plasma, Seiler, K.; Wang, K.; Bakker, E.; Morf, W.E.; Rusterholz, B.; Spichiger, U.E.; Simon, W. Clin. Chem., 1991, 37, 1350-1355. DOI: 10.1093/clinchem/37.8.1350.