Ls55 fluorometer

Manufactured by PerkinElmer

Sourced in United Kingdom

The LS55 fluorometer is a versatile instrument used for fluorescence measurements. It is designed to detect and quantify fluorescent compounds in a variety of sample types. The LS55 provides accurate and reliable fluorescence data, enabling researchers to analyze their samples effectively.

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Lab products found in correlation

Nano zs instrument, by Malvern Panalytical (1 mentions) Uv vis u 3501 spectrophotometer, by PerkinElmer (1 mentions) Quartz cuvette, by PerkinElmer (1 mentions) Lambda 35 uv vis, by PerkinElmer (1 mentions) Zetasizer nano z, by Malvern Panalytical (1 mentions) Lambda 25 uv vis spectrometer, by PerkinElmer (1 mentions)

Close spelling variants of this product

Life Sciences LS55 model fluorometer

10 protocols using ls55 fluorometer

Fluorescence Spectroscopy Protocols

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The absorption
and steady-state fluorescence spectra were acquired on Hitachi UV–vis
U-3501 spectrophotometer and PerkinElmer LS55 fluorometer, respectively.
The time-resolved fluorescence decay measurements (lifetime and fluorescence
anisotropy measurements) were carried out by the time-correlated single
photon counting (TCSPC) method⁵⁸ on a FluoroCube-01-NL
spectrometer using a laser diode (model: DD-450L-8666, typical fwhm
∼170 ps) as the light source for excitation of the samples
at λ_ex = 450 nm. The signals were collected at the
magic angle polarization of 54.7° in order to eliminate the contribution
from fluorescence depolarization.⁵⁸ Dynamic
light-scattering (DLS) measurements were performed on a Malvern Nano-ZS
instrument equipped with a thermostated sample chamber (Laser source:
4 mW He–Ne laser having λ = 632.8 nm, scattering angle
= 173°). Each of the fluorescence decay and fluorescence depolarization
profiles reported in this work were reproduced for four individual
measurements. Detailed description of the instrumentations and experimental
protocols/procedures is given in the Supporting Information.

Sett R., Sen S., Paul B.K, & Guchhait N. (2018). How Does Nanoconfinement within a Reverse Micelle Influence the Interaction of Phenazinium-Based Photosensitizers with DNA?. ACS Omega, 3(2), 1374-1385.

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Bacterial Adhesion to Skin Cells

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Bacterial adhesion to skin cell monolayers experiments were performed in 24-well plates to 70-90% confluence. The medium was removed, the cells were washed twice with PBS, and then blocked with 10% FBS in DMEM for 2 h at 37 °C in a 5% CO₂ atmosphere. After that, cells were washed with PBS, and 100 μl of FITC-labeled bacteria in 500 μl of DMEM were added. The mixture was incubated for 1 h at 37 °C in a 5% CO₂ atmosphere. To remove the unbound bacteria, wells were rinsed four times with 500 μl of PBS. At the end of the experiments, skin cell monolayers were disaggregated with 1% SDS and the fluorescence of the bacteria attached to them was quantified in a Perkin Elmer LS55 fluorometer, at 488 nm for excitation and 560 nm for emission. Data were normalized using the adhesion values from the control, which were given a value of 1. Assays were performed at least in triplicate and the data are expressed as the mean ± SD.

Martín C., Ordiales H., Vázquez F., Pevida M., Rodríguez D., Merayo J., Vázquez F., García B, & Quirós L.M. (2022). Bacteria associated with acne use glycosaminoglycans as cell adhesion receptors and promote changes in the expression of the genes involved in their biosynthesis. BMC Microbiology, 22, 65.

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Light Scattering Assay of Clavaspirin Peptides

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Light scattering assays were performed with clavaspirin and its analogue peptides using a Perkin-Elmer LS55 fluorometer. Peptides were dissolved in 10 mM sodium phosphate buffer (pH 5.5 or pH 7.4) and incubated for 12 h at 37° C. Light scattering was excited at 400 nm and the emission was scanned at 400 nm [35 (link)].

Lee J.K., Luchian T, & Park Y. (2018). New antimicrobial peptide kills drug-resistant pathogens without detectable resistance. Oncotarget, 9(21), 15616-15634.

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FtsZ Polymerization Kinetics Analysis

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A reaction mix was prepared in a cold Eppendorf® tube where SaFtsZ (1 mg/mL) was mixed with the test compound at the desired concentration and a polymerization buffer diluted from a double strength buffer to give a final concentration of 25 mM PIPES pH 6.8, 50 mM KCl and 10 mM MgCl₂. The reaction mix was prepared such that the DMSO concentration remained constant at 2% (v/v). The mix was then added into a quartz cuvette (PerkinElmer®, United Kingdom), and placed in a PerkinElmer® LS 55 fluorometer under the fixed condition of excitation/emission at 350/350 nm, slit width <2 nm, a 1 s read interval. The temperature was calibrated to remain constant at 20 °C. The fluorescence was followed for 300 s to allow equilibration, then polymerization was initiated with the addition of 1 mM GTP. A separate negative control was prepared where 1 mM GDP was added instead of the GTP. The reaction was followed for 600 s.

Chai W.C., Whittall J.J., Song D., Polyak S.W., Ogunniyi A.D., Wang Y., Bi F., Ma S., Semple S.J, & Venter H. (2020). Antimicrobial Action and Reversal of Resistance in MRSA by Difluorobenzamide Derivatives Targeted at FtsZ. Antibiotics, 9(12), 873.

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Quantifying Hydroxyl Radical Scavenging Capacity

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In vitro generation of the hydroxyl radical was carried out using the Fenton reaction involving Fe²⁺-EDTA/H₂O₂, during which peroxide decomposition to OH^● occurs [77 (link)]. These radicals react with terephthalic acid to form 2-hydroxyterephthalate acid, which has a high fluorescence. The reaction mixture consisted of 100 μL of the different extracts diluted in water, 300 μL of a 1 × 10⁻⁴ M sodium terephthalate solution, 2420 μL of phosphate buffer (0.2 M and pH 7.4), 90 μL of an EDTA (ethylenediaminetetraacetic acid disodium salt dihydrate) solution (1 × 10⁻² M), and 90 μL of Fe²⁺ (1 × 10⁻² M). The kinetics of the reaction was followed for 6 min in a LS-55 fluorometer (Perkin-Elmer, Waltham, MA, USA) at an excitation λ of 326 nm and an emission λ of 432 nm, with slits of 10 nm, without attenuation [78 (link)]. The results were presented as the ability to scavenge hydroxyl radicals, using Equation (4).

% H y d r o x y l r a d i c a l a c t i v i t y = (\frac{A_{2} - A_{0}}{A_{1} - A_{0}}) \times 100,

where A₀ is the absorbance of the blank, A₁ is the absorbance of the control (without sample), and A₂ is the absorbance of the samples.

Alzate-Arbelaez A.F., Cortés F.B, & Rojano B.A. (2022). Antioxidants from Hyeronima macrocarpa Berries Loaded on Nanocellulose: Thermal and Antioxidant Stability. Molecules, 27(19), 6661.

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Membrane Permeabilization Assay for S. aureus

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S. aureus CCARM 259237 cells were grown to the mid-log phase and suspended in 10 mM sodium phosphate buffer supplemented with 10% culture medium at pH 7.4 and 37° C, and then washed and suspended (2 × 10⁷ cfu/mL) in 10 mM sodium phosphate buffer (pH 7.4) and incubated with 1 μM SYTOX-Green for 20 min in the dark. After the addition of peptides at the appropriate concentrations (1/2 MIC, MIC, 2× MIC, and/or 4× MIC), time-dependent increases in fluorescence, which is caused by the binding of the cationic dye to intracellular nucleic acids, was monitored using a Perkin-Elmer LS55 fluorometer (excitation wavelength, 485 nm; emission wavelength, 520 nm) [40 (link)].

Lee J.K., Luchian T, & Park Y. (2018). New antimicrobial peptide kills drug-resistant pathogens without detectable resistance. Oncotarget, 9(21), 15616-15634.

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Optical Characterization of Molecular Systems

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UV-vis absorption spectra were obtained on a Lambda 35 UV-vis (Perkin-Elmer) spectrometer with a path length of 1 cm. Fluorescence studies were performed on a LS55 Fluorometer (Perkin-Elmer) with a path length of either 1 cm or 3 mm. For determination of Φ_em, solutions were prepared to an optical density of less than 0.05 in order to minimize inner filter effects. Perylene in cyclohexane was used as a reference for quantum yields.²⁴ Emission lifetime measurements were performed on an EasyLife II (Photon Technology International) using a 340 nm pulsed LED.

Wilson J.N., Liu W., Brown A.S, & Landgraf R. (2015). Binding-induced, turn-on fluorescence of the EGFR/ERBB kinase inhibitor, lapatinib. Organic & biomolecular chemistry, 13(17), 5006-5011.

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Comprehensive Characterization of Materials

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The visible light spectrum was studied using a PerkinElmer Lambda 25 UV–Vis spectrometer in the range 200–800 nm. Scanning electron microscopy (SEM) images were obtained using an XL30 ESEM FEG scanning electron microscope. X-ray powder diffraction (XRD) spectroscopy was performed using a Philips diffractometer. A Fourier transform infrared (FT-IR) spectrometer (Shimadzu 8400S) was used to record the FTIR spectra. The fluorescence spectra were measured using an LS-55 fluorometer (PerkinElmer) in the wavelength range of 280–600 nm. Energy dispersive X-ray spectroscopy (EDX) was conducted with a Tescan model energy dispersive spectrometer, and for the measurement of zeta-potential, a Zetasizer Nano-Z (Malvern Instruments, UK) was applied.

Dehnoei M., Ahmadi-Sangachin E, & Hosseini M. (2024). Colorimetric and fluorescent dual-biosensor based on zirconium and preasodium metal-organic framework (zr/pr MOF) for miRNA-191 detection. Heliyon, 10(6), e27757.

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Porphyrin Extraction and Quantification

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Intracellular porphyrins obtained from ALA or derivatives were extracted with 5% HCl employing a modification of the method described previously [14] (link). The cells were centrifuged at 3000 x g after acid extraction, and afterwards, the pellet was discarded, and the supernatant was kept for porphyrin determinations. The fluorescence signal was recorded in a Perkin Elmer LS55 fluorometer (Buckinghamshire, UK) ( ex= 406 nm and em= 604 nm). A solution of PpIX in 5% HCl (Frontier Scientific, Logan, US) was employed as standard. The half-maximum effective concentrations of the ALA or derivatives (EC50s) were determined as the concentrations leading to half the maximal porphyrin values.

Vallecorsa P., Di Venosa G., Gola G., Sáenz D., Mamone L., MacRobert A.J., Ramírez J, & Casas A. (2021). Photodynamic therapy of cutaneous T-cell lymphoma cell lines mediated by 5-aminolevulinic acid and derivatives. Journal of photochemistry and photobiology. B, Biology, 221.

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Kinetic Study of β-N-Acetylhexosaminidase Variants

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A standard 120 mL assay was conducted at 37 C in 50 mM sodium phosphate buffer (pH 5.0) containing various concentrations (2.5-500 mM) of GalNAc-NIR-MP. The reaction was initiated by the addition of 50 nM of WT-Hex, Hex-K432Lys(PA), Hex-K561Lys(PA) or Hex-K561Lys-(M6P) 3 -Rh to the above assay solution. Changes in fluorescence intensity of an NIR dye was detected using an LS 55 fluorometer (Perkin-Elmer TM Life Sciences) (l ex = 690 nm, l em = 710 nm). Assays were performed in triplicate. By plotting the initial reaction velocity as the function of a concentration of GalNAc-NIR-MP, a typical Michaelis-Menten curve was obtained. The kinetic parameters (k cat and K m ) were determined by non-linear fitting of this plot using the Michaelis-Menten equation.
Cleavage of GM2-oligosaccharide to GM3-oligosaccharide by b-N-Acetylhexosaminidase WT-Hex, Hex-K561Lys(PA) and Hex-K561Lys-(M6P) 3 -Rh (10 nM) were individually added to a solution of GM2 oligosaccharide (300 nM) in 50 mM sodium phosphate buffer (pH 5.0) in a final volume of 20 mL at 37 C. The progress of enzymatic hydrolysis was monitored by thin layer chromatography (ethyl acetate: ethanol: water = 4:2:1). The reaction was terminated by addition of MeOH (20 mL).

Hyun J.Y., Kim S., Lee H.S, & Shin I. (2018). A Glycoengineered Enzyme with Multiple Mannose-6-Phosphates Is Internalized into Diseased Cells to Restore Its Activity in Lysosomes. Cell chemical biology, 25(10).

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