Platinum Meso-tetra Research Articles

Preparation and characterization of dually fluorescent core–shell particles and dual-sensing membranes for simultaneous detection of pH and dissolved oxygen

In this study, two dually fluorescent core–shell particles based on the response of 8-hydroxypyrene-1,3,6-trisulfonic acid trisodium salt (HPTS) and platinum meso-tetra (pentafluorophenyl) porphyrin (PtP) were prepared for simultaneous detection of dissolved oxygen (pO2) and pH. The first involved forming a core–shell structure by capturing PtP in polystyrene (PS) particles as the core (PS@PtP) and then coating HPTS on the surface of PS@PtP via a supporting layer of melamine–formaldehyde resin as the shell. The second comprised covalently binding HPTS to a shell layer of sol–gel coated onto the surface of PS@PtP. The fluorescent particles from either method were immobilized in a supporting polymer matrix of ethyl cellulose (EC) and polyurethane hydrogel HydroMed D4 (D4) to produce the dual-sensing membranes. The resulting two dual-sensing membranes showed high sensitivity to pO2 in the range of 0–100% pO2 and to pH in the range of pH 5–9. They also showed high reproducibility, less interference, and long-term stability. A ratiometric fluorescence method was also applied to the dual emissions from HPTS and PtP to correct for a variety of analyte-independent factors and to provide precise quantitative analysis.

Ratiometric Fluorescent Biosensors for Glucose and Lactate Using an Oxygen-Sensing Membrane.

In this study, ratiometric fluorescent glucose and lactate biosensors were developed using a ratiometric fluorescent oxygen-sensing membrane immobilized with glucose oxidase (GOD) or lactate oxidase (LOX). Herein, the ratiometric fluorescent oxygen-sensing membrane was fabricated with the ratio of two emission wavelengths of platinum meso-tetra (pentafluorophenyl) porphyrin (PtP) doped in polystyrene particles and coumarin 6 (C6) captured into silica particles. The operation mechanism of the sensing membranes was based on (i) the fluorescence quenching effect of the PtP dye by oxygen molecules, and (ii) the consumption of oxygen levels in the glucose or lactate oxidation reactions under the catalysis of GOD or LOX. The ratiometric fluorescent glucose-sensing membrane showed high sensitivity to glucose in the range of 0.1–2 mM, with a limit of detection (LOD) of 0.031 mM, whereas the ratiometric fluorescent lactate-sensing membrane showed the linear detection range of 0.1–0.8 mM, with an LOD of 0.06 mM. These sensing membranes also showed good selectivity, fast reversibility, and stability over long-term use. They were applied to detect glucose and lactate in artificial human serum, and they provided reliable measurement results.

Development of a Ratiometric Fluorescent Glucose Sensor Using an Oxygen-Sensing Membrane Immobilized with Glucose Oxidase for the Detection of Glucose in Tears.

Glucose concentration is an important parameter in biomedicine since glucose is involved in many metabolic pathways in organisms. Many methods for glucose detection have been developed for use in various applications, particularly in the field of healthcare in diabetics. In this study, ratiometric fluorescent glucose-sensing membranes were fabricated based on the oxygen levels consumed in the glucose oxidation reaction under the catalysis of glucose oxidase (GOD). The oxygen concentration was measured through the fluorescence quenching effect of an oxygen-sensitive fluorescent dye like platinum meso-tetra (pentafluorophenyl) porphyrin (PtP) by oxygen molecules. Coumarin 6 (C6) was used as a reference dye in the ratiometric fluorescence measurements. The glucose-sensing membrane consisted of two layers: The first layer was the oxygen-sensing membrane containing polystyrene particles (PS) doped with PtP and C6 (e.g., PS@C6^PtP) in a sol–gel matrix of aminopropyltrimethoxysilane and glycidoxypropyltrimethoxysilane (GA). The second layer was made by immobilizing GOD onto one of three supporting polymers over the first layer. These glucose-sensing membranes were characterized in terms of their response, reversibility, interferences, and stability. They showed a wide detection range to glucose concentration in the range of 0.1 to 10 mM, but high sensitivity with a linear detection range of 0.1 to 2 mM glucose. This stable and sensitive ratiometric fluorescent glucose biosensor provides a reliable way to determine low glucose concentrations in blood serum by measuring tear glucose.

One-pot doping platinum porphyrin recognition centers in Zr-based MOFs for ratiometric luminescent monitoring of nitric oxide in living cells

A new kind of nanoscale MOFs probe for nitric oxide (NO) sensing has been successfully constructed by a one-pot strategy, in which the chemically stable UiO-66 crystal structure was achieved using platinum meso-tetra(4-carboxyphenyl)porphyrin (Pt-TCPP), 1,1,2,2-Tetra(4-carboxylphenyl)ethylene (H4TCPE) and 1,4-dicarboxybenzene (BDC) as co-linkers (Pt-TCPP/H4TCPE@UiO-66). Pt-TCPP was verified to serve as a signal reporter in NO sensing fields for the first time while H4TCPE worked as a luminescence reference to build a ratiometric sensor. The integration of luminescent dyes in nanoscale MOFs effectively avoided their aggregation-caused quenching effect and poor aqueous dispersibility to rationalize NO detection in the aqueous phase. The obtained Pt-TCPP/H4TCPE@UiO-66 nanoparticles (NPs) exhibited an excellent sensing property toward NO with an ultrahigh linear correlation of the Stern-Volmer equation and a rapid response time as short as 2 min. Moreover, the elaborated sensor could work under a wide pH window (7.4, 5.6 and 0) and the limit of detection (LOD) reached as low as 0.1420 µg mL-1. The specificity of the obtained Pt-TCPP/H4TCPE@UiO-66 NPs toward NO sensing was scarcely affected by other possibly coexistent species in biological system. The in vitro monitoring for NO in living cells was also testified with these Pt-TCPP/H4TCPE@UiO-66 NPs.

Portable optical oxygen sensor based on time-resolved fluorescence.

A new, simple signal processing, low-cost technique for the fabrication of a portable oxygen sensor based on time-resolved fluorescence is described. The sensing film uses the oxygen sensing dye platinum meso-tetra (pentfluorophenyl) porphyrin (PtTFPP) embedded in a polymer matrix. The ratio τ0/τ100 measures sensitivity of the sensing film, where τ0 and τ100 represent the detected fluorescence lifetimes from the sensing film exposed to 100% nitrogen and 100% oxygen, respectively. The experimental results reveal that the PtTFPP-doped oxygen sensor has a sensitivity of 2.2 in the 0%-100% range. A preparation procedure for coating the photodiodes with the oxygen sensor film that produces repetitive and reliable sensing devices is proposed. The developed time-resolved optical oxygen sensor is portable, low-cost, has simple signal processing, and lacks optical filter elements. It is a cost-effective alternative to traditional electrochemical-based oxygen sensors and provides a platform for other optical based sensors.

Signal drift of oxygen optical sensors. Part I: Rationalization of the drift nature and its experimental check with a light intensity detection based sensor

A way to quantify the signal drift causes of an oxygen optical sensor is reported. Theoretical formalization were experimentally confirmed by using a polysulfone-based thin layer membrane embedding platinum meso-tetra-(pentafluorophenyl)-porphyrine working in light emission detection mode. Photochemical, thermal and oxidative degradation of both luminophore and polymeric matrix were rationalized and tested. Experimentally determinable light intensity drift, DI, and Stern–Volmer constant (K′SV) drift, DK, were related to matrix and luminophore modifications. The mathematical modeling of the drift evidenced that DI, is constant by increasing the %O2 only in the absence of DK. It has been possible to quantify all the contributions independently through a very good match between theory and experiments. The sensor drift analysis allowed understanding whether luminophore and/or polymer degradations were operative. In the studied caseoxidative degradation was absent; thermal degradation of the sole luminophore, was independent of %O2 and caused a relative light intensity drift of −0.028(0.002) day−1; photochemical degradation was present both on luminophore and polymeric matrix. When DK≠0, either light intensity and phase-shift and the life-time based detection modes lead to incorrect oxygen concentration values. The results reported in this paper suggest the design of a new, simple, cheap and robust light intensity-based sensor working with high accuracy and precision. This will be done in the Part II of the workby setting up an algorithm able to correct all the drift effects operating during the life-time of the sensor.

Studies on the oxygen sensitivity and microstructure of sol–gel based organic–inorganic hybrid coatings doped with platinum porphyrin dye

Hybrid organic–inorganic nanocomposite coatings were prepared by copolymerizing tetraethylorthosilicate with ethyltriethoxysilane with an acid catalysis process. Oxygen sensor coatings were fabricated by doping the hybrid sol with platinum meso-tetra(pentfluorophenyl) porphyrin. Photophysical properties and oxygen sensitivity of the sensor coatings were studied. The microstructure of the coatings was examined using optical microscopy and scanning electron microscopy. The effect of sol–gel process conditions like precursor silane molar ratio, acid concentration and stirring time of the sol on the oxygen sensitivity and surface microstructure of the sensor coating was studied. Oxygen sensitivity and surface morphology of the coatings were dependent on the sol–gel process parameters.