scholarly journals Screening for Optimal Liposome Preparation Conditions by Using Dual Centrifugation and Time-Resolved Fluorescence Measurements

Pharmaceutics ◽  
2021 ◽  
Vol 13 (12) ◽  
pp. 2046
Author(s):  
Jonas K. Koehler ◽  
Johannes Schnur ◽  
Heiko Heerklotz ◽  
Ulrich Massing
Keyword(s):  
Lipid Composition ◽  
Screening Method ◽  
Water Soluble ◽  
Time Resolved Fluorescence ◽  
Screening Process ◽  
Lipid Film ◽  
Time Resolved ◽  
Lipid Mixture ◽  
Fluorescence Measurements ◽  
Liposome Preparation

Dual centrifugation (DC) is a novel in-vial homogenization technique for the preparation of liposomes in small batch sizes under gentle and sterile conditions which allows encapsulation efficiencies (EE) for water soluble compounds of >50%. Since liposome size, size distribution (PDI), and EE depend on the lipid concentration used in the DC process, a screening method to find optimal lipid concentrations for a defined lipid composition was developed. Four lipid mixtures consisting of cholesterol, hydrogenated or non-hydrogenated egg PC, and/or PEG-DSPE were screened and suitable concentration ranges could be identified for optimal DC homogenization. In addition to the very fast and parallel liposome preparation of up to 40 samples, the screening process was further accelerated by the finding that DC generates homogeneously mixed liposomes from a macroscopic lipid mixture without the need to initially prepare a molecularly mixed lipid film from an organic solution of all components. This much simpler procedure even works for cholesterol containing lipid blends, which could be explained by a nano-milling of the cholesterol crystals during DC homogenization. Furthermore, EE determination was performed by time-resolved fluorescence measurements of calcein-loaded liposomes without removing the non-entrapped calcein. The new strategy allows the rapid characterization of a certain lipid composition for the preparation of liposomes within a working day.

scholarly journals A Luminescent, Water-Soluble Ir(III) Complex as a Potential Photosensitizer for Two-Photon Photodynamic Therapy

2021 ◽  
Vol 11 (24) ◽  
pp. 11596
Author(s):  
Elisabeta I. Szerb ◽  
Sharmistha Chatterjee ◽  
Massimo La Deda ◽  
Giovanna Palermo ◽  
Lucie Sancey ◽  
...  
Keyword(s):  
Photodynamic Therapy ◽  
Water Soluble ◽  
In Vitro Experiments ◽  
Time Resolved Fluorescence ◽  
Time Resolved ◽  
Biologically Relevant ◽  
Two Photon ◽  
Fluorescence Measurements ◽  
Detection Probe

This work reports the study of two-photon induced properties of a highly luminescent cyclometalated Ir(III) complex, [Ir(ppy)2(en)] OOCCH3 (1), ppy = 2-phenylpyridine, en = ethylenediamine. Steady-state and time-resolved fluorescence measurements were performed by exciting 1 at the biologically relevant wavelength of 800 nm, whereas, the generation of singlet oxygen (1O2) was evaluated using 9,10-Anthracenediyl-bis(methylene)dimalonic acid (ABDA) as a detection probe. Preliminary in vitro experiments with U87-MG cells were performed, showing the potential of this compound as a two-photon photodynamic therapy (2P-PDT) agent at NIR wavelengths.

Sensitive, rapid procedure for time-resolved immunofluorometry of lutropin.

1988 ◽  
Vol 34 (8) ◽  
pp. 1640-1644 ◽  
Author(s):  
M J Khosravi ◽  
R C Morton ◽  
E P Diamandis
Keyword(s):  
Monoclonal Antibody ◽  
Solid Phase ◽  
Detection System ◽  
Time Resolved Fluorescence ◽  
Time Resolved ◽  
Practical Procedure ◽  
Daily Monitoring ◽  
Fluorescence Measurements ◽  
Capture Antibody ◽  
Europium Chelate

Abstract In this new immunofluorometric method for quantification of lutropin in serum, the "sandwich" principle is combined with time-resolved fluorescence measurements, with the europium chelate 4,7-bis(chlorosulfophenyl)-1,10-phenanthroline-2,9-dicarboxylic acid (BCPDA) used as label. A monoclonal antibody to the alpha-subunit of lutropin is adsorbed onto the walls of white-opaque microtiter wells to form the solid-phase capture antibody, and a biotin-labeled soluble monoclonal antibody is used for antigen quantification. The detection system is completed with streptavidin, which has been linked to a protein bulking agent labeled with multiple BCPDA residues. In the presence of excess europium, the fluorescence of the final complex attached to captured lutropin molecules is measured on the dried solid phasse with an automated time-resolved fluorometer. The assay can be performed as a rapid (less than 60 min incubation) or regular (150 min incubation) procedure. The rapid assay is well-suited for routine daily monitoring of increasing or ovulatory lutropin concentrations; the regular assay, with its greater sensitivity (0.5 int. unit/L), is a practical procedure for lutropin measurements in hyposecretory states. The assay measures up to 240 int. units/L, and results compare well with those by a commercially available radioimmunoassay, an immunoradiometric assay, and another time-resolved immunofluorometric procedure.

scholarly journals Development, Characterization, and Application of a Versatile Single Particle Detection Apparatus for Time-Integrated and Time-Resolved Fluorescence Measurements—Part II: Experimental Evaluation

2009 ◽  
Vol 2009 ◽  
pp. 1-14
Author(s):  
Xihong Wu ◽  
J. A. Merten ◽  
N. Omenetto ◽  
B. W. Smith ◽  
J. D. Winefordner
Keyword(s):  
Single Particle ◽  
Narrow Beam ◽  
Time Resolved Fluorescence ◽  
Particle Detection ◽  
Time Resolved ◽  
Endogenous Fluorophores ◽  
Fluorescence Measurements ◽  
On Line ◽  
Single Particle Detection ◽  
Speed Mode

This paper describes the experimental realization and characterization of a versatile single particle detection apparatus. The system utilizes a novel particle beam inlet that can serve as either an on-line particle concentrator (i.e., all diameters confined in a narrow beam) or as a segregator (i.e., selected diameters confined in a narrow beam) and can be operated in a high-speed mode as well as in a low-speed mode, thus allowing different interaction times between the particles and the laser beam. An aerodynamic sizing technique has been incorporated into the system to provide rapid, real-time, and high-resolution sizing. Parameters such as transmission efficiency and size-segregation efficiency have been measured. The performance of the instrument has been demonstrated by on-line detection of spectrally resolved and time resolved fluorescence detection from airborne dye-doped particles and aerosolized endogenous fluorophores found in biological agents.

Fluorescence property of photosystem II protein complexes bound to a gold nanoparticle

2017 ◽  
Vol 198 ◽  
pp. 121-134 ◽  
Author(s):  
Kazuki Tahara ◽  
Ahmed Mohamed ◽  
Kousuke Kawahara ◽  
Ryo Nagao ◽  
Yuki Kato ◽  
...  
Keyword(s):  
Photosystem Ii ◽  
Gold Nanoparticle ◽  
Water Oxidation ◽  
Artificial Photosynthesis ◽  
Fluorescence Property ◽  
Light Illumination ◽  
Time Resolved Fluorescence ◽  
Strong Light ◽  
Time Resolved ◽  
Fluorescence Measurements

Development of an efficient photo-anode system for water oxidation is key to the success of artificial photosynthesis. We previously assembled photosystem II (PSII) proteins, which are an efficient natural photocatalyst for water oxidation, on a gold nanoparticle (GNP) to prepare a PSII–GNP conjugate as an anode system in a light-driven water-splitting nano-device (Noji et al., J. Phys. Chem. Lett., 2011, 2, 2448–2452). In the current study, we characterized the fluorescence property of the PSII–GNP conjugate by static and time-resolved fluorescence measurements, and compared with that of free PSII proteins. It was shown that in a static fluorescence spectrum measured at 77 K, the amplitude of a major peak at 683 nm was significantly reduced and a red shoulder at 693 nm disappeared in PSII–GNP. Time-resolved fluorescence measurements showed that picosecond components at 683 nm decayed faster by factors of 1.4–2.1 in PSII–GNP than in free PSII, explaining the observed quenching of the major fluorescence peak. In addition, a nanosecond-decay component arising from a ‘red chlorophyll’ at 693 nm was lost in time-resolved fluorescence of PSII–GNP, probably due to a structural perturbation of this chlorophyll by interaction with GNP. Consistently with these fluorescence properties, degradation of PSII during strong-light illumination was two times slower in PSII–GNP than in free PSII. The enhanced durability of PSII is an advantageous property of the PSII–GNP conjugate in the development of an artificial photosynthesis device.

An integrated instrumentation for light‐scattering and time‐resolved fluorescence measurements

1995 ◽  
Vol 66 (3) ◽  
pp. 2405-2410 ◽  
Author(s):  
M. Musolino ◽  
R. Cubeddu ◽  
A. Pifferi ◽  
P. Taroni ◽  
P. Lago ◽  
...  
Keyword(s):  
Light Scattering ◽  
Time Resolved Fluorescence ◽  
Time Resolved ◽  
Fluorescence Measurements

Phosphorescent porphyrin probes in biosensors and sensitive bioassays

2000 ◽  
Vol 28 (2) ◽  
pp. 74-77 ◽  
Author(s):  
D. B. Papkovsky ◽  
T. O'Riordan ◽  
A. Soini
Keyword(s):  
Oxygen Sensor ◽  
Spectral Characteristics ◽  
Screening Method ◽  
High Sensitivity ◽  
Water Soluble ◽  
Fluorescent Detection ◽  
Rapid Screening ◽  
Time Resolved ◽  
Phosphorescence Lifetime ◽  
Practical Applications

Platinum(II) and palladium(II) complexes of porphyrins and related tetrapyrrolic pigments emit strong phosphorescence at room temperatures, which is characterized by long lifetimes falling into the sub-millisecond range and long-wave spectral characteristics. These features make the dyes useful as probes for a number of bioanalytical applications, particularly those employing time-resolved fluorescent detection. They can provide high sensitivity and selectivity, together with rather simple instrumental set-up. A number of analytical systems are now under development that are based on the use of phosphorescent porphyrin probes. Experimental results are presented on the following systems: (i) fibre-optic phosphorescence lifetime-based oxygen sensor on the basis of hydrophobic platinum-porphyrins and development of advanced sensing materials and prototype instrumentation; (ii) practical applications of the optical oxygen sensor, including a sensitive immunosensor that employs glucose oxidase labels, a rapid screening method for cell viability in microtitre-plate format, non-destructive measurement of oxygen in packaged foods and reagentless biosensors for metabolites (glucose, lactate); and (iii) the use of water-soluble platinum- and palladium-porphyrins as labels for ultra-sensitive time-resolved phosphorescence immunoassays.

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