Fluorescent Optode Research Articles

Optical fiber chemical sensing of anionic surfactants using a microfluidic polymer chip with embedded ion-selective fluorescence optode.

This study introduces a novel microfluidic polymer chip system that employs an embedded anionic surfactant (AS) ion-selective fluorescence optode (AS fluorescence optode) as a detector for measuring AS. The AS fluorescent optode comprises a lactone form of rhodamine B (L-RB) embedded in 2-nitrophenyl octyl ether plasticized poly (vinyl chloride) membrane. The AS fluorescence optode demonstrated a linear correlation between fluorescence intensity peak heights and AS concentrations within the range of less than 20µM under optimal flow conditions. The limit of detection for AS was approximately 0.06µM. The microfluidic system was utilized to measure AS levels in environmental samples, such as river water and tap water.

A Selective Fluorescent Optode for Lead(II) Based on the Dansylamidopropyl Pendant Arm Derivative of 1,4-Dioxa-7,13-dithia-10-azacyclopentadecane ([15]aneNS2O2)

In this study, a novel highly sensitive and selective fluorescent optode membrane aimed at the determination of Pb(II) ion is proposed by incorporating N-(3-(1,4-dioxa-7,13-dithia-10-azacyclopentadecan-10-yl)propyl)-5-(dimethylamino)naphthalene-1-sulfonamide (L) as fluoroionophore in polyvinyl chloride (PVC) containing 2-nitrophenyl octylether (NPOE) as a plasticizer. In addition to high stability and reproducibility, the proposed optosensor showed a unique selectivity toward Pb(II) ion, with a wide linear range of molar concentrations (1.0 × 10−9–1.0 × 10−3 M) and a low detection limit of 7.5 × 10−10 M in solution at pH 5.0. The formation constants of the Pb(II) complexes with the fluoroionophore were evaluated by fitting the fluorescence data with a nonlinear least-squares curve-fitting program, and further information about the structures of the complexes were evaluated based on hybrid-DFT calculations. The optosensor exhibited a fast response time of less than three min, being easily regenerated by exposure to a solution of dithiothreitol. The sensor was applied to the determination of Pb(II) in real samples (canned tuna fish), and it provided satisfactory results comparable to those obtained via atomic absorption spectrometry (AAS).

A Fluorescent Optode Membrane Covalently Immobilized with a Donor–Acceptor Conjugated Dye for pH Sensing under Extremely Acidic Conditions

Figure S1 SEM image of the optode membrane on the glass plate. Figure S2. Linear calibration curve for the absorbance ratio change from pH 0.0 to 2.0. Figure S3. 1H NMR spectrum of compound 2. Figure S4. 13C NMR spectrum of compound 2. Figure S5. Mass spectrum of compound 2. Figure S6. 1H NMR spectrum of compound 3. Figure S7. 13C NMR spectrum of compound 3. Figure S8. Mass spectrum of compound 3. Please note: The publisher is not responsible for the content or functionality of any supporting information supplied by the authors. Any queries (other than missing content) should be directed to the corresponding author for the article.

A light activated CMP conjugated 8-aminoquinoline turn-on fluorescent optode for selective determination of Th4+ in an aqueous environment.

A new dibutyl(2-oxo-2-(quinolin-8-ylamino)ethyl)phosphinate (L) was designed, synthesised and developed as a light activated optode for Th4+ determination. The sensing performance of L was studied in solution and in the polymeric membrane phase using absorbance and emission techniques. The neutral ion carrier L exhibits weak fluorescence at 400 nm in CH3CN : H2O (9 : 1, v/v). Upon complexation of L with Th4+, the emission intensity at 486 nm was increased 100-fold due to chelation induced enhanced fluorescence. The L-Th4+ binding interaction was studied using both Hill's and Job's plots. They indicate the formation of complex species in a 2 : 1 ratio with an estimated binding constant of 2.66 × 104 M-2. Complex formation between L and Th4+ was studied by NMR (1H, 31P), FTIR and LC-MS analyses. In order to synthesize a probe for the sensing of Th4+ in 100% aqueous medium, the optode was prepared by immobilizing L as a neutral ion carrier in a PVC support using dioctyl phthalate (DOP) as a membrane solvent. The best performance of the optode was observed with a membrane composition of PVC : L : NaTPB : DOP in proportions of 35 : 5 : 3 : 57 (%, w/w) in the pH range of 4.0-8.0. The optode can detect Th4+ concentrations down to 1.1 nM with a fast response time of 15 s and the optical response remains unaltered even after 3 months; the optode sensor can be regenerated using Na2EDTA solution. Finally, the optode was used for the quantification of Th4+ in various water samples, monazite sand, and gas mantle samples.

Repeated measurement of Mo2 in small aquatic organisms: a manual intermittent flow respirometer using off-the-shelf components.

Measurement of rates of oxygen consumption ( Mo2) in small aquatic embryos or larvae (<1 mm) in response to altered environmental conditions has traditionally been challenging. Here, using modifications of a commercially available fluorescent optode flow-through cell (FTC; PreSens FTC-PSt3) and routine laboratory supplies (syringes, stopcocks, tubing), we have constructed a manual intermittent flow respirometer (MIFR) that allows measurement of Mo2 in small numbers of individuals when sequentially exposed to different environmental conditions (e.g., changes in seawater pH) through a gravity-driven media replacement perfusion system. We first show that the FTC can be used in "static" mode while incubating small numbers of embryos/larvae contained within the planar oxygen sensor (POS) chamber with Nitex filters. We then demonstrate the use of the MIFR by exposing larval echinoderms ( Fellaster zelandiae, Evechinus chloroticus, and Centrostephanus rodgersii) to seawater equilibrated with elevated CO2 and measured Mo2 during acute and chronic exposure to hypercapnia. This MIFR method will allow investigators to address questions regarding the respiratory physiology of small aquatic animals, such as the thresholds for metabolic depression in embryonic and larval forms. NEW & NOTEWORTHY A manual intermittent flow respirometer (MIFR), allowing media exchange in a flow-through cell containing small aquatic organisms, permits repeated measurement of Mo2 of individuals not only in a single medium (e.g., technical replication), but also in different media (here, high CO2-equilibrated seawater), enabling measurement of acute physiological responses to changed conditions. This versatile technique has wide-ranging implications for the study of the Mo2 response of aquatic organisms in the face of climate change.

A Novel Fluorimetric Bulk Optode Membrane Based on NOS Tridentate Schiff Base for Selective Optical Sensing of Al3+ Ions.

A novel fluorimetric optode has been developed for the highly selective and sensitivefor the determination of ultra trace amounts of Al3+ ions. The proposed fluorescent optode is based on the incorporation of a simple and effective fluorescent sensor tridentate NOS Schiff base N-(2-hydroxynaphthylidene)-2-aminothiophenol (H2L) in a plasticized PVC containing KTpClPB as a lipophilic anionic additive. H2L was synthesized by a facile one-step Schiff base reaction. The plasticized PVC-membrane displays a calibration response for Al3+ ions over a wide concentration range from1.0×10-9 to 4.4×10-3mol/L. The fluorescence signal of the optode membrane can be easily recovered by immersion in 0.01M EDTA. In addition to high stability and reproducibility, the sensor shows a unique selectivity towards Al3+ ion with respect to common co-existing cations, particularly Ga3+and In3+. The proposed optode was applied successfully for determination of Al3+ in some real samples, including bottled drinking waters, bottled mineral waters and soft drinks.

A Novel Fluorescent Cesium Ion-Selective Optode Membrane based on 15-Crown-5-Anthracene

An optode system based on a plasticized polymer membrane containing cesium ion-selective fluoroionophore and lipophilic anions for the determination of cesium ions has been developed. In this work, 15-crown-5 derivative including anthracene was used as a fluoroionophore. Emission intensity of the optode membrane incorporating 15-crown-5-anthracene was measured at 500 nm with excitation at 360 nm in the presence of Tris-HCl buffer solution. Under optimum experimental condition, the relative fluorescence intensity was linear with the concentration of cesium ion in the range of 1.0 × 10(-4) M to 1.0 × 10(-1) M and the detection limit was obtained 4.2 × 10(-5) M, as defined by LOD=3 × S(b)/m (where S(b)=standard deviation of blank signal and, m=slope of the calibration curve). The effect of pH of sample solution on the fluorescent response, the selectivity, response time and reproducibility of the optode membrane were also discussed. The fluorescent optode system shows a high selectivity and sensitivity for cesium ion with respect to other cations such as K(+), Na(+) and Li(+).

Miniaturized setup for fluorescence sensing with optodes: Characterization of a new hemicyanine ion-selective-based membrane

A miniaturized and robust optical fluorosensor, designed as a portable instrumentation for the in situ analysis of ions in water samples by using optodes has been constructed with low cost discrete optical components. The chemical recognition element of the device consists of a plasticized PVC-based fluorescent optode, which includes a new hexamethine–hemicyanine dye as a fluorophore. The signal can be attributed to a certain analyte depending on the ionophore employed. In this work, a commercial potassium ionophore (valinomycin) has been used to formulate a model membrane selective to potassium. The sensor has been fully characterized using a simple flow injection analysis (FIA) system and analytical parameters such as sensitivity (0.71 mV dec −1 ), limit of detection (2.2 × 10 −5 M K + ), repeatability (R.S.D. = 4.2%), reproducibility, lifetime and ionic interferences have been determined. The developed miniaturized system has been applied to the potassium concentration determination in spiked tap water samples. The obtained results have been compared to those acquired by the ICP-OES reference method and the suitability of the experimental setup for the determination of ions in water samples by the miniaturized fluorescence proposal has been demonstrated.

Selective Fluorimetric Recognition of Cesium Ion by 15-Crown-5-Anthracene

A selective fluorescent cesium optode on a chromoionophore consisting of anthracene covalently linked through an imine bond to a 15-crown-5 derivative has been reported. In the present system, 15-crown-5 derivative including anthracene was used a fluoroionophore. The fluorescence response mechanism is based on the photo-induced electron transfer (PET) from the lone pair of electrons of the nitrogen to the anthracene group and inhibition of PET system by cesium binding while increasing the fluorescence intensity. Emission intensity 15-crown-5 anthracene was measured at 500 nm with absorbance at 400 nm in CH(3)CN-H(2)O (1:1) media. The method shows a very good selectivity and sensitivity for cesium with respect to other cations such as K(+), Na(+) and Li(+) with linear range and detection limit of 5.0 x 10(-5) to 5.0 x 10(-1)M and 3.0 x 10(-6)M respectively.

Fluorescent microsphere fiber optic microsensor array for direct iodide detection at low picomolar concentrations

Fluorescent optode microspheres doped with the halide-selective receptor [9]mercuracarborand-3 and a lipophilic pH fluoroionophore were found to exhibit picomolar limits of detection to iodide at pH 3.5, and were used to monitor the precipitation of iodide by silver ions at subnanomolar concentrations, just above their calculated solubility.

광센서를 이용한 수용액 중 납이온의 형광분광법적 정량

납이온과 선택적으로 상호작용하는 이온 운반물질(lead ionophore II)과 수소이온과 선택적으로 상호작용하면서 형광을 내는 변색성 이온 운반물질(ETH5294) 및 소수성의 음이온 자리를 포함하는 이온 선택성 광센서를 제조하여 형광분광법으로 수용액 중의 납이온을 정량하는 방법을 연구하였다. 시료용액의 pH,막두께 등이 형광세기에 미치는 영향을 조사하였다. <TEX>$Na^+$</TEX>, <TEX>$K^+$</TEX>, <TEX>$Mn^{2+}$</TEX> 및 <TEX>$Zn^{2+}$</TEX>이온 등의 방해이온이 납이온의 정량에 미치는 영향을 조사하였다.본 연구에서 제작한 납이온 선택성 막을 이용하여 얻은 납이온 검정곡선의 직선범위는 5.0<TEX>${\times}10^-7$</TEX>M5.0<TEX>${\times}10^-3$</TEX>M이였고 이 범위에서의 상관계수는 -0099107이었다. 바탕용액의 상대표준편차는 3.0%였고 납이온의 검출한계는 5.0<TEX>${\times}10^-9$</TEX>M이었다. A method to determine lead ion in aqueous media using an optical sensor loaded on a fluorescent optode membrane incoporating a metal ion-selective ionophore, a proton-selective chromoionophore and lipophilic anionic sites has been studied. The effects of pH and thickness of membrane on the fluorescence intensity were investigated. The effects of foreign ions such as <TEX>$Na^+$</TEX>, <TEX>$K^+$</TEX>, <TEX>$Mn^{2+}$</TEX> and <TEX>$Zn^{2+}$</TEX> on the determination of lead ion were also studied. The linear range in the calibration curve for the determination of lead ion was found to be 5.0<TEX>${\times}10^-7$</TEX> to 5.0<TEX>${\times}$</TEX><TEX>$10^-3$</TEX>M and the correlation coefficient in this range was -0.99107 under the optimal experimental conditions. The relative standard deviation of the blank signals was 3.0% and the detection limit of lead ion was 5.0<TEX>${\times}$</TEX><TEX>$10^-9$</TEX>M.

Lead-selective fluorescent optode membrane based on 3,3′,5,5′-tetramethyl- N-(9-anthrylmethyl)benzidine

A new proton-selective fluorescing indicator, 3,3′,5,5′-tetramethyl- N-(9-anthrylmethyl)benzidine (TMANB) has been synthesized and applied in an optode membrane for the determination of lead ion that works on the basis of a cation-exchange mechanism. When embedded in a plasticized poly(vinyl chloride) (PVC) membrane containing lead ionophore ( tert-butylcalix[4]arene-tetrakis( N, N-dimethylthioacetamide)) and a lipophilic anionic site [potassium tetrakis(4-chlorophenyl)borate], TMANB shows a significant fluorescence signal change on exposure to aqueous HCl solution containing lead ion, which exhibits the theoretically expected fluorescence response to lead ion concentration. The selectivity, response time, reproducibility and reversibility, and lifetime of the optode membrane were discussed.

A sodium ion selective optode based on fluorescein octadecyl ether octadecyl ester and application in beverage and urine assay

A fast responsive sodium ion selective fluorescent optode membrane mounted on an optical fiber has been developed. The sensing membrane contained fluorescein octadecyl ether octadecyl ester (FODEE), potassium tetrakis(4-chlorophenyl) borate (KT pClPB) and a calix[4]arene tetraester in a plasticized poly(vinyl chloride) (PVC) matrix. It exhibited a reversible response to Na + in 0.5 mol/l of HCl in the concentration range of 1.0×10 −6 to 0.1 mol/l. The selectivity, response time, reproducibility and lifetime of the optode membrane were discussed. The practical use of this sensor was demonstrated by real sample analysis in complex sample solutions such as beverage and urine samples.

Development of a fluorescent optode membrane for sodium ion based on the calix[4]arene and tetraphenylporphine

A fluorescent optode membrane for sodium ion that works on the basis of a cation-exchange mechanism has been developed. The plasticized poly(vinyl chloride) (PVC) membrane incorporating sodium-selective ionophore (4- tert-butylcalix[4]arene tetraacetic acid tetraethyl ester), acidic fluorescent pH indicator (5,10,15,20-tetraphenylporphine, TPP) and a lipophilic anionic site (potassium tetrakis(4-chlorophenyl)borate) was used as the sensing device, which exhibits the theoretically expected fluorescent response to sodium ion. The selectivity, response time, reproducibility and lifetime of the optode membrane were discussed.

A fluorescent optode for sodium ion based on the inner filter effect

A fluorescent optode for sodium ion has been developed based on the inner filter effect (IFE). A suitable fluorescing compound (5, 10, 15, 20-tetraphenylporphine (TPP)) is incorporated in a plasticized poly(vinyl chloride) (PVC) membrane containing the sodium-selective ionophore (calix[4]arene derivative) and the proton-selective chromoionophore (ETH5294). On account of the overlap between the fluorescent emission spectrum of TPP and the absorption spectrum of ETH5294, fluorescence intensity of such a PVC membrane varies as a function of the varying absorbance of ETH5294 induced by sodium concentration due to the IFE. The optode showed excellent selectivity and reversibility to sodium ion over the range of 5 × 10 −5–1 mol l −1 with a response time of less than 2 min. The proposed method offers a general approach, which can be applied to any other cations by replacing the sodium-selective ionophore with any other suitable cation-selective one.

Fluorescent optode membrane based on organogel for humidity sensing

Optode membranes for use in the quantitative detection of relative humidity were developed by entrapping a fluorescent dye, Sulforhodamin 101, in gelatine-containing microemulsion-based organogels deposited on overhead transparency films. These organogels are fabricated from solutions of Sulforhodamin 101, sodium bis(2-ethylhexyl)sulfosuccinate and gelatine in water–isooctane solvent mixtures. These optode membranes exhibit strong fluorescence emission with excitation and emission maxima at 588 and 608 nm, respectively. The fluorescence emission intensity decreases with increase in relative humidity and yields a linear response range of relative humidity from 35 to 100% with a correlation coefficient of 0.991 at room temperature. Response and recovery times are within 1 min. The optode membranes show good repeatability and photostability and a long lifetime. Oxygen and carbon dioxide gases do not cause any interference. Other organic solvent vapours have a very slight interference on the optode membranes. The optode membranes were successfully applied for the measurement of relative humidity in different laboratory airs.

Evaluation of an on-demand, ex vivo bedside blood gas monitor on pulmonary artery blood gas determinations.

Critically ill patients often have cardiopulmonary perturbations that require rapid and frequent assessment for optimal care, including cardiac output determinations, measurement of cardiac filling pressures, and arterial and mixed venous blood gas determinations. We evaluated the performance of a rapid, on-demand bedside blood gas monitor to determine arterial and mixed venous blood gas values. The blood gas monitor uses fluorescent optode technology to directly measure Po2, Pco2, and pH. This measurement is accomplished by aspirating blood from the artery or vein into a sampling chamber where it interfaces with the fluorescent optode. After approximately 90 s of equilibration, the blood gas values are reported. Since the blood is drawn into the sampling chamber, it can be returned to the patient, thus eliminating the need for phlebotomy. We studied 15 critically ill patients requiring systemic and pulmonary arterial catheterization. Conventional blood gas analysis was performed simultaneously. The results obtained from the blood gas monitor were compared with those obtained via traditional blood gas analysis using Bland-Altman plots and examination of bias and precision. The results were well within the expected clinical variance. During the study period, there was no interference with patient care or adverse events related to the use of the monitoring system. In conclusion, the blood gas monitor can provide rapid, accurate determinations of arterial and mixed venous blood gases allowing optimal therapeutic interventions in critically ill patients.

Preliminary evaluation of an intra-arterial blood gas system in dogs and humans.

The reliability and accuracy of an intra-arterial fluorescent optode system to measure continuously pHa, PaCO2, and PaO2 were evaluated in a dog model and in a group of critically ill patients. Six hundred sixty-three arterial blood gas (ABG) samples were analyzed for pHa, PaCO2, and PaO2 in the dog studies. The intra-arterial blood gas system (IBGS) indicated a steady state in 420 instances for pH, 359 instances for PaCO2, and 256 instances for PaO2. Comparison of these ABG and IBGS values by linear regression analysis revealed r = .97 for pHa, .95 for PaCO2, and .96 for PaO2. The mean +/- SD of the difference between ABG and IBGS was -0.02 +/- 0.03 for pHa, 1.05 +/- 3.8 for PaCO2, and -17 +/- 13 for PaO2. Nonsteady states were correctly identified by the IBGS in every instance. Comparisons between 79 temporally matched ABG and IBGS values, exclusive of in vivo calibration samples, in 12 critically ill patients revealed r = .97 for pHa, .96 for PaCO2, and .99 for PaO2. The difference was 0.002 +/- 0.02 for pHa, 0.44 +/- 2.97 for PaCO2, and -1.22 +/- 9.34 for PaO2. We conclude that it is possible to measure continuously pHa, PaCO2, and PaO2 with the IBGS in critically ill patients for periods from 3 to 25.5 h while maintaining the ability to monitor BP and withdraw blood samples from the arterial cannula. Agreement between the two techniques is within clinically acceptable ranges for pHa and PaCO2, whereas PaO2 measurement by the IBGS requires further refinement.(ABSTRACT TRUNCATED AT 250 WORDS)