Publications by authors named "I Gryczynski"

364 Publications

On the origin and correction for inner filter effects in fluorescence. Part II: secondary inner filter effect -the proper use of front-face configuration for highly absorbing and scattering samples.

Methods Appl Fluoresc 2021 May 24;9(3). Epub 2021 May 24.

Department of Physics and Astronomy, Texas Christian University, Fort Worth, TX, 76109, United States of America.

Fluorescence is an established technology for studying molecular processes and molecular interactions. More recently fluorescence became a leading method for detection, sensing, medical diagnostics, biotechnology, imaging, DNA analysis, and gene expression. Consequently, precise and accurate measurements in various conditions have become more critical for proper result interpretations. Previously, in Part 1, we discussed inner filter effect type I, which is a consequence of the instrumental geometrical sensitivity factor and absorption of the excitation. In this part, we analyze inner filter effect type II and discuss the practical consequences for fluorescence measurements in samples of high optical density (absorbance/scattering). We consider both the standard square and front-face experimental configurations, discuss experimental approaches to limit/mitigate the effect and discuss methods for correcting and interpreting experimental results.
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http://dx.doi.org/10.1088/2050-6120/ac0243DOI Listing
May 2021

The Luminescence of 1,8-Diazafluoren-9-One/Titanium Dioxide Composite Thin Films for Optical Application.

Materials (Basel) 2020 Jul 6;13(13). Epub 2020 Jul 6.

Department of Biopharmaceutics and Pharmacodynamics, Medical University of Gdańsk, Al. Gen. Hallera 107, 80-416 Gdańsk, Poland.

The investigation of innovative label-free α-amino acids detection methods represents a crucial step for the early diagnosis of several diseases. While 1,8-diazafluoren-9-one (DFO) is known in forensic application because of the fluorescent products by reacting with the amino acids present in the papillary exudate, its application for diagnostic purposes has not been fully investigated. The stabilization of DFO over a transparent substrate allows its complexation with biomolecules for the detection of α-amino acids. In this study, DFO was immobilized into a titanium dioxide (TiO) matrix for the fluorescence detection of glycine, as a target α-amino acid (a potential marker of the urogenital tract cancers). The DFO/TiO composite was characterized by atomic force microscopy, spectroscopic ellipsometry, fluorescence spectroscopy and fluorescence microscopy. The performed fluorescent studies indicate spectacular formation of aggregates at higher concentration. The measurements performed using various fluorescence and microscopic techniques together with the suitable analysis show that the aggregates are able to emit short-lived fluorescence.
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http://dx.doi.org/10.3390/ma13133014DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7372385PMC
July 2020

On the possibility of direct triplet state excitation of indole.

J Photochem Photobiol B 2020 Jul 16;208:111897. Epub 2020 May 16.

Department of Microbiology, Immunology, and Genetics, Center for Fluorescence Technologies and Nanomedicine, University of North Texas Health Science Center, Fort Worth, TX 76107, USA.

We studied the luminescence properties of indole in poly (vinyl alcohol) (PVA) film. The indole molecules are effectively immobilized in this polymer film and display both fluorescence and phosphorescence emission at room temperature. We noticed that the phosphorescence of indole in PVA film can be effectively excited at a longer wavelength than its typical singlet to triplet population route involving intersystem crossing. The maximum of the phosphorescence excitation is about 410 nm which corresponds to the energy of indole's triplet state. Interestingly, the phosphorescence anisotropy excited with the longer wavelength (405 nm) is positive and reaches a value of about 0.25 in contrast to the phosphorescence anisotropy excited within the indole singlet absorption spectrum (290 nm), which is negative. Very different temperature dependences have been observed for fluorescence and phosphorescence of indole in PVA film. While fluorescence depends minimally, the phosphorescence decreases with temperature dramatically. The fluorescence lifetime was measured to be a single component 4.78 ns while the intensity weighted average phosphorescence lifetime with 290 nm and 405 nm excitations were 6.57 and 5.62 ms, respectively. We believe that the possibility of the excitation of indole phosphorescence in the blue region of visible light and its high anisotropy opens a new avenue for future protein studies.
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http://dx.doi.org/10.1016/j.jphotobiol.2020.111897DOI Listing
July 2020

On the origin and correction for inner filter effects in fluorescence Part I: primary inner filter effect-the proper approach for sample absorbance correction.

Methods Appl Fluoresc 2020 Jun 1;8(3):033002. Epub 2020 Jun 1.

Department of Physics and Astronomy, Texas Christian University, Fort Worth, TX, 76109, United States of America.

Fluorescence technologies have been the preferred method for detection, analytical sensing, medical diagnostics, biotechnology, imaging, and gene expression for many years. Fluorescence becomes essential for studying molecular processes with high specificity and sensitivity through a variety of biological processes. A significant problem for practical fluorescence applications is the apparent non-linearity of the fluorescence intensity resulting from inner-filter effects, sample scattering, and absorption of intrinsic components of biological samples. Sample absorption can lead to the primary inner filter effect (Type I inner filter effect) and is the first factor that should be considered. This is a relatively simple factor to be controlled in any fluorescence experiment. However, many previous approaches have given only approximate experimental methods for correcting the deviation from expected results. In this part we are discussing the origin of the primary inner filter effect and presenting a universal approach for correcting the fluorescence intensity signal in the full absorption range. Importantly, we present direct experimental results of how the correction works. One considers problems emerging from varying absorption across its absorption spectrum for all fluorophores. We use Rhodamine 800 and demonstrate how to properly correct the excitation spectra in a broad wavelength range. Second is the effect of an inert absorber that attenuates the intensity of the excitation beam as it travels through the cuvette, which leads to a significant deviation of observed results. As an example, we are presenting fluorescence quenching of a tryptophan analog, NATA, by acrylamide and we show how properly corrected results compare to the initial erroneous results. The procedure is generic and applies to many other applications like quantum yield determination, tissue/blood absorption, or acceptor absorption in FRET experiments.
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http://dx.doi.org/10.1088/2050-6120/ab947cDOI Listing
June 2020

Probing the Assembly of HDL Mimetic, Drug Carrying Nanoparticles Using Intrinsic Fluorescence.

J Pharmacol Exp Ther 2020 04 15;373(1):113-121. Epub 2020 Jan 15.

Departments of Physiology and Anatomy (S.R., A.G., B.N., N.S., A.L.) and Microbiology, Immunology and Genetics (R.F., I.G., Z.G., J.B.), UNT Health Science Center, Fort Worth, Texas; National Heart, Lung and Blood Institute, National Institutes of Health, Bethesda, Maryland (A.R.); and Departments of Physics and Astronomy (Z.G.) and Chemistry and Biochemistry (S.V.D.), Texas Christian University, Fort Worth, Texas

Reconstituted high-density lipoprotein (HDL) containing apolipoprotein A-I (Apo A-I) mimics the structure and function of endogenous (human plasma) HDL due to its function and potential therapeutic utility in atherosclerosis, cancer, neurodegenerative diseases, and inflammatory diseases. Recently, a new class of HDL mimetics has emerged, involving peptides with amino acid sequences that simulate the the primary structure of the amphipathic alpha helices within the Apo A-I protein. The findings reported in this communication were obtained using a similar amphiphilic peptide (modified via conjugation of a myristic acid residue at the amino terminal aspartic acid) that self-assembles (by itself) into nanoparticles while retaining the key features of endogenous HDL. The studies presented here involve the macromolecular assembly of the myristic acid conjugated peptide (MYR-5A) into nanomicellar structures and its characterization via steady-state and time-resolved fluorescence spectroscopy. The structural differences between the free peptide (5A) and MYR-5A conjugate were also probed, using tryptophan fluorescence, Fӧrster resonance energy transfer (FRET), dynamic light scattering, and gel exclusion chromatography. To our knowledge, this is the first report of a lipoprotein assembly generated from a single ingredient and without a separate lipid component. The therapeutic utility of these nanoparticles (due to their capablity to incorporate a wide range of drugs into their core region for targeted delivery) was also investigated by probing the role of the scavenger receptor type B1 in this process. SIGNIFICANCE STATEMENT: Although lipoproteins have been considered as effective drug delivery agents, none of these nanoformulations has entered clinical trials to date. A major challenge to advancing lipoprotein-based formulations to the clinic has been the availability of a cost-effective protein or peptide constituent, needed for the assembly of the drug/lipoprotein nanocomplexes. This report of a robust, spontaneously assembling drug transport system from a single component could provide the template for a superior, targeted drug delivery strategy for therapeutics of cancer and other diseases (Counsell and Pohland, 1982).
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http://dx.doi.org/10.1124/jpet.119.262899DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7160862PMC
April 2020