Mykhaylo Losytskyy | Taras Shevchenko National University of Kyiv (original) (raw)

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Papers by Mykhaylo Losytskyy

Research paper thumbnail of Sensing of Proteins by ICD Response of Iron(II) Clathrochelates Functionalized by Carboxyalkylsulfide Groups

Biomolecules, 2020

Recognition of elements of protein tertiary structure is crucial for biotechnological and biomedi... more Recognition of elements of protein tertiary structure is crucial for biotechnological and biomedical tasks; this makes the development of optical sensors for certain protein surface elements important. Herein, we demonstrated the ability of iron(II) clathrochelates (1–3) functionalized with mono-, di- and hexa-carboxyalkylsulfide to induce selective circular dichroism (CD) response upon binding to globular proteins. Thus, inherently CD-silent clathrochelates revealed selective inducing of CD spectra when binding to human serum albumin (HSA) (1, 2), beta-lactoglobuline (2) and bovine serum albumin (BSA) (3). Hence, functionalization of iron(II) clathrochelates with the carboxyalkylsulfide group appears to be a promising tool for the design of CD-probes sensitive to certain surface elements of proteins tertiary structure. Additionally, interaction of 1–3 with proteins was also studied by isothermal titration calorimetry, protein fluorescence quenching, electrospray ionization mass spe...

Research paper thumbnail of Phthalocyanines with out-of-plane quinolinium styryl ligand as inhibitors of insulin amyloid fibrils formation

Research paper thumbnail of Author response for "Inhibition of heat‐induced protein aggregation by zirconium phthalocyanines

Research paper thumbnail of Fluorescent β-ketoenole AmyGreen dye for visualization of amyloid components of bacterial biofilms

Methods and Applications in Fluorescence, 2020

Green-emitting water-soluble amino-ketoenole dye AmyGreen is proposed as an efficient fluorescent... more Green-emitting water-soluble amino-ketoenole dye AmyGreen is proposed as an efficient fluorescent stain for visualization of bacterial amyloids in biofilms and the detection of pathological amyloids in vitro. This dye is almost non-fluorescent in solution, displays strong green emission in the presence of amyloid fibril of proteins. AmyGreen is also weakly fluorescent in presence to biomolecules that are components of cells, extracellular matrix or medium: nucleic acids, polysaccharides, lipids, and proteins. Thus, the luminescence turn-on behavior of AmyGreen can be utilized for visualization of amyloid components of bacterial biofilm extracellular matrix. Herein we report the application of AmyGreen for fluorescent staining of a number of amyloid-contained bacteria biofilms produced by Escherichia coli, Klebsiella pneumoniae, Pseudomonas aeruginosa, Bordetella avium, and Staphylococcus aureus. The effectiveness of AmyGreen was compared to traditional amyloid sensitive dye Thioflavine T. The main advantage of AmyGreen (concentration 10-5 M) is a higher sensitivity in the visualization of amyloid biofilm components over Thioflavine T (10-4 M) as it was revealed when staining E. coli and K. pneumoniae bacterial biofilms. Besides, AmyGreen displays lower cross-selectivity to nucleic acids as demonstrated both in in-solution experiments and upon staining of eukaryotic human mesenchymal stem cells used as amyloid-free negative control over amyloid-rich bacterial biofilms. The results point to a lower risk of false-positive response upon determination of amyloid components of bacterial biofilm using AmyGreen. Co-staining of biofilm by AmyGreen and cellulose sensitive dye Calcofluor White show difference in their staining patterns and localization, indicating separation of polysaccharide-rich and amyloid-rich regions of investigated biofilms. Thus, we suggest the new AmyGreen stain for visualization and differentiation of amyloid fibrils in bacterial biofilms to be used solely and in combination with other stains for confocal and fluorescence microscopy analysis.

Research paper thumbnail of Energy Transfer in Polystyrene Nanoparticles with Encapsulated 2,5-Diphenyloxazole

French-Ukrainian Journal of Chemistry, 2015

As the first step to design nanosystems for X-ray excited sensitising of singlet oxygen, nanopart... more As the first step to design nanosystems for X-ray excited sensitising of singlet oxygen, nanoparticles of polystyrene (PS NP) and polystyrene with encapsulated diphenyloxazole molecules (PS-PPO NP) were synthesized. Inside the PS-PPO NP, the electronic excitation energy transfer from polystyrene matrix to encapsulated PPO molecules takes place; efficiency of such transfer was roughly estimated to be about 0.37. X-ray stimulated luminescence of PS-PPO NP was registered.

Research paper thumbnail of Modification of insulin amyloid aggregation by Zr phthalocyanines functionalized with dehydroacetic acid derivatives

PLOS ONE

Amyloid fibrils are widely studied both as target in conformational disorders and as basis for th... more Amyloid fibrils are widely studied both as target in conformational disorders and as basis for the development of protein-based functional materials. The three Zr phthalocyanines bearing dehydroacetic acid residue (PcZr(L1)2) and its condensed derivatives (PcZr(L2)2 and PcZr(L3)2) as out-of-plane ligands were synthesized and their influence on insulin fibril formation was studied by amyloid-sensitive fluorescent dye based assay, scanning electron microscopy, fluorescent and absorption spectroscopies. The presence of Zr phthalocyanines was shown to modify the fibril formation. The morphology of fibrils formed in the presence of the Zr phthalocyanines differs from that of free insulin and depends on the structure of out-of-plane ligands. It is shown that free insulin mostly forms fibril clusters with the length of about 0.3–2.1 μm. The presence of Zr phthalocyanines leads to the formation of individual 0.4–2.8 μm-long fibrils with a reduced tendency to lateral aggregation and cluster ...

Research paper thumbnail of Design of functionalized β-ketoenole derivatives as efficient fluorescent dyes for detection of amyloid fibrils

New Journal of Chemistry

Functionalized β-ketoenoles for efficient fluorescence sensing of protein amyloid fibrils giving ... more Functionalized β-ketoenoles for efficient fluorescence sensing of protein amyloid fibrils giving strong emission increase up to 0.5 QY are designed.

Research paper thumbnail of Study of tetraphenylporphyrins as modifiers of insulin amyloid aggregation

Journal of Molecular Recognition

Research paper thumbnail of Dicarboxyl-terminated iron(ii) clathrochelates as ICD-reporters for globular proteins

RSC Advances

Method of asymmetric mono-ribbed functionalization of iron(ii) clathrochelates is developed, new ... more Method of asymmetric mono-ribbed functionalization of iron(ii) clathrochelates is developed, new compounds are studied as ICD reporters for globular proteins.

Research paper thumbnail of Induced CD of iron(ii) clathrochelates: sensing of the structural and conformational alterations of serum albumins

Metallomics

Iron(ii) clathrochelates are protein-sensitive CD reporters able to discriminate proteins of simi... more Iron(ii) clathrochelates are protein-sensitive CD reporters able to discriminate proteins of similar structure (HSA and BSA) and reflect the transitions of protein conformation.

Research paper thumbnail of The impact of binding of macrocyclic metal complexes on amyloid fibrillization of insulin and lysozyme

Journal of Molecular Recognition

Research paper thumbnail of β-ketoenole dyes: Synthesis and study as fluorescent sensors for protein amyloid aggregates

Dyes and Pigments, 2016

The series of the new β-ketoenole dyes ((2E,5Z,7E,9E)-6-hydroxy-2-(alkylamino)-10-phenyldeca-2,5,... more The series of the new β-ketoenole dyes ((2E,5Z,7E,9E)-6-hydroxy-2-(alkylamino)-10-phenyldeca-2,5,7,9-tetraen-4-ones) with variation of alkylamino tail groups was synthesized and studied as potential probes for the sensing of protein aggregates amyloid fibrils. The dyes are low fluorescent when free but able to increase their emission intensity in dozens of times in the presence of fibrillar insulin. The fluorescent response of the dye on fibrillar insulin strongly depends on the nature of the alkylamino tail group. For compounds with propylamino (dye 13) and 2-hydroxyethylamino (dye 14) fragments the fluorescence intensity in the presence of fibrillar insulin exceeds that for the native one in 22 and 66 times correspondingly. However dyes demonstrate from low or moderate exceed of the fluorescence intensity in the presence of aggregated lysozyme compared to native one (up to 8.7 times for the dye 53 bearing methyl ester tail group), due to their pronounced sensitivity to native lysozyme. The dyes in complexes with insulin have rather height quantum yield up to 0.15, the large Stokes shifts values (about 100 nm and more), their binding constant values are about 10 5 M-1. The dye 14 allows fluorescent detection of the insulin amyloid fibrils in the concentration range 1-50 μg/ml. This causes an interest in the future study of the β-ketoenole as prospective fluorescent amyloid-sensitive molecules.

Research paper thumbnail of Detection of Polyamino Acids Using Trimethincyanine Dyes

Research paper thumbnail of Use of Squaraine Dyes to Visualize Protein During Separations

Research paper thumbnail of Novel dyes and compositions, and processes for using same in analysis of protein aggregation and other applications

Research paper thumbnail of Dyes for analysis of protein aggregation

Research paper thumbnail of Temperature Dependence of Photoluminescence from Silver Nanoparticles

Research paper thumbnail of Sensing the temperature influence on plasmonic field of metal nanoparticles by photoluminescence of fullerene C60 in layered C60/Au system Sensing the temperature influence on plasmonic field of metal nanoparticles by photoluminescence of fullerene C 60 in layered C 60 /Au system

Journal of Applied Physics

Influence of temperature on the plasmonic field in the temperature range of 78–278 K was studied ... more Influence of temperature on the plasmonic field in the temperature range of 78–278 K was studied employing surface plasmon enhanced photoluminescence from the fullerene C60 thin film deposited on 2D array of Au nanoparticles. It was experimentally found that temperature dependence of plasmonic enhancement factor of C60 luminescence decreases monotonically with the temperature increase. Influence of temperature on plasmonic enhancement factor was found to be considerably stronger when the frequency of surface plasmon absorption band of Au nanoparticles and the frequency of fullerene luminescence band are in resonance. Electron-phonon scattering and thermal expansion of Au nanoparticles were considered as two competing physical mechanisms of the temperature dependence of plasmonic field magnitude. The calculations revealed significant prevalence of the electron-phonon scattering. The temperature induced increase in the scattering rate leads to higher plasmon damping that causes the de...

Research paper thumbnail of Photoluminescence of rhodamine 6G in plasmonic field of Au nanoparticles: Temperature effects

Influence of temperature on the photoluminescence of rhodamine 6G deposited on 2D array of the go... more Influence of temperature on the photoluminescence of rhodamine 6G deposited on 2D array of the gold nanoparticles was studied in the temperature range of 78-278 K. The factor of surface plasmonic enhancement of rhodamine luminescence was found to decrease monotonically with increasing temperature. Electron-phonon scattering and thermal expansion of the gold nanoparticles were considered as two competing physical mechanisms of the temperature dependence of plasmonic enhancement factor. The calculations showed the significant prevalence of the electron-phonon scattering. The temperature induced increase of the scattering rate leads to higher plasmon damping that causes the decrease of plasmonic enhancement of rhodamine 6G luminescence.

Research paper thumbnail of Interaction of the Iron(II) Cage Complexes With Proteins: Protein Fluorescence Quenching Study

Journal of Fluorescence, 2013

Interaction of the iron(II) mono-and bisclathrochelates with bovine serum albumin (BSA), β-lactog... more Interaction of the iron(II) mono-and bisclathrochelates with bovine serum albumin (BSA), β-lactoglobulin, lysozyme and insulin was studied by the steady-state and time-resolved fluorescent spectroscopies. These cage complexes do not make significant impact on fluorescent properties of β-lactoglobulin, lysozyme and insulin. At the same time, the monoclathrochelates strongly quench a fluorescence intensity of BSA and substantially decrease its excited state lifetime due to their binding to this protein. This occurs due to the excitation energy transfer from a tryptophan residue to a cage molecule or/and to the change of the tryptophan nearest environment caused by either clathrochelate binding or an alteration of the BSA conformation. The effect of the iron(II) bis-clathrochelate on BSA fluorescence is much weaker as compared to its monomacrobicyclic analogs as a result of an increase in its size.

Research paper thumbnail of Sensing of Proteins by ICD Response of Iron(II) Clathrochelates Functionalized by Carboxyalkylsulfide Groups

Biomolecules, 2020

Recognition of elements of protein tertiary structure is crucial for biotechnological and biomedi... more Recognition of elements of protein tertiary structure is crucial for biotechnological and biomedical tasks; this makes the development of optical sensors for certain protein surface elements important. Herein, we demonstrated the ability of iron(II) clathrochelates (1–3) functionalized with mono-, di- and hexa-carboxyalkylsulfide to induce selective circular dichroism (CD) response upon binding to globular proteins. Thus, inherently CD-silent clathrochelates revealed selective inducing of CD spectra when binding to human serum albumin (HSA) (1, 2), beta-lactoglobuline (2) and bovine serum albumin (BSA) (3). Hence, functionalization of iron(II) clathrochelates with the carboxyalkylsulfide group appears to be a promising tool for the design of CD-probes sensitive to certain surface elements of proteins tertiary structure. Additionally, interaction of 1–3 with proteins was also studied by isothermal titration calorimetry, protein fluorescence quenching, electrospray ionization mass spe...

Research paper thumbnail of Phthalocyanines with out-of-plane quinolinium styryl ligand as inhibitors of insulin amyloid fibrils formation

Research paper thumbnail of Author response for "Inhibition of heat‐induced protein aggregation by zirconium phthalocyanines

Research paper thumbnail of Fluorescent β-ketoenole AmyGreen dye for visualization of amyloid components of bacterial biofilms

Methods and Applications in Fluorescence, 2020

Green-emitting water-soluble amino-ketoenole dye AmyGreen is proposed as an efficient fluorescent... more Green-emitting water-soluble amino-ketoenole dye AmyGreen is proposed as an efficient fluorescent stain for visualization of bacterial amyloids in biofilms and the detection of pathological amyloids in vitro. This dye is almost non-fluorescent in solution, displays strong green emission in the presence of amyloid fibril of proteins. AmyGreen is also weakly fluorescent in presence to biomolecules that are components of cells, extracellular matrix or medium: nucleic acids, polysaccharides, lipids, and proteins. Thus, the luminescence turn-on behavior of AmyGreen can be utilized for visualization of amyloid components of bacterial biofilm extracellular matrix. Herein we report the application of AmyGreen for fluorescent staining of a number of amyloid-contained bacteria biofilms produced by Escherichia coli, Klebsiella pneumoniae, Pseudomonas aeruginosa, Bordetella avium, and Staphylococcus aureus. The effectiveness of AmyGreen was compared to traditional amyloid sensitive dye Thioflavine T. The main advantage of AmyGreen (concentration 10-5 M) is a higher sensitivity in the visualization of amyloid biofilm components over Thioflavine T (10-4 M) as it was revealed when staining E. coli and K. pneumoniae bacterial biofilms. Besides, AmyGreen displays lower cross-selectivity to nucleic acids as demonstrated both in in-solution experiments and upon staining of eukaryotic human mesenchymal stem cells used as amyloid-free negative control over amyloid-rich bacterial biofilms. The results point to a lower risk of false-positive response upon determination of amyloid components of bacterial biofilm using AmyGreen. Co-staining of biofilm by AmyGreen and cellulose sensitive dye Calcofluor White show difference in their staining patterns and localization, indicating separation of polysaccharide-rich and amyloid-rich regions of investigated biofilms. Thus, we suggest the new AmyGreen stain for visualization and differentiation of amyloid fibrils in bacterial biofilms to be used solely and in combination with other stains for confocal and fluorescence microscopy analysis.

Research paper thumbnail of Energy Transfer in Polystyrene Nanoparticles with Encapsulated 2,5-Diphenyloxazole

French-Ukrainian Journal of Chemistry, 2015

As the first step to design nanosystems for X-ray excited sensitising of singlet oxygen, nanopart... more As the first step to design nanosystems for X-ray excited sensitising of singlet oxygen, nanoparticles of polystyrene (PS NP) and polystyrene with encapsulated diphenyloxazole molecules (PS-PPO NP) were synthesized. Inside the PS-PPO NP, the electronic excitation energy transfer from polystyrene matrix to encapsulated PPO molecules takes place; efficiency of such transfer was roughly estimated to be about 0.37. X-ray stimulated luminescence of PS-PPO NP was registered.

Research paper thumbnail of Modification of insulin amyloid aggregation by Zr phthalocyanines functionalized with dehydroacetic acid derivatives

PLOS ONE

Amyloid fibrils are widely studied both as target in conformational disorders and as basis for th... more Amyloid fibrils are widely studied both as target in conformational disorders and as basis for the development of protein-based functional materials. The three Zr phthalocyanines bearing dehydroacetic acid residue (PcZr(L1)2) and its condensed derivatives (PcZr(L2)2 and PcZr(L3)2) as out-of-plane ligands were synthesized and their influence on insulin fibril formation was studied by amyloid-sensitive fluorescent dye based assay, scanning electron microscopy, fluorescent and absorption spectroscopies. The presence of Zr phthalocyanines was shown to modify the fibril formation. The morphology of fibrils formed in the presence of the Zr phthalocyanines differs from that of free insulin and depends on the structure of out-of-plane ligands. It is shown that free insulin mostly forms fibril clusters with the length of about 0.3–2.1 μm. The presence of Zr phthalocyanines leads to the formation of individual 0.4–2.8 μm-long fibrils with a reduced tendency to lateral aggregation and cluster ...

Research paper thumbnail of Design of functionalized β-ketoenole derivatives as efficient fluorescent dyes for detection of amyloid fibrils

New Journal of Chemistry

Functionalized β-ketoenoles for efficient fluorescence sensing of protein amyloid fibrils giving ... more Functionalized β-ketoenoles for efficient fluorescence sensing of protein amyloid fibrils giving strong emission increase up to 0.5 QY are designed.

Research paper thumbnail of Study of tetraphenylporphyrins as modifiers of insulin amyloid aggregation

Journal of Molecular Recognition

Research paper thumbnail of Dicarboxyl-terminated iron(ii) clathrochelates as ICD-reporters for globular proteins

RSC Advances

Method of asymmetric mono-ribbed functionalization of iron(ii) clathrochelates is developed, new ... more Method of asymmetric mono-ribbed functionalization of iron(ii) clathrochelates is developed, new compounds are studied as ICD reporters for globular proteins.

Research paper thumbnail of Induced CD of iron(ii) clathrochelates: sensing of the structural and conformational alterations of serum albumins

Metallomics

Iron(ii) clathrochelates are protein-sensitive CD reporters able to discriminate proteins of simi... more Iron(ii) clathrochelates are protein-sensitive CD reporters able to discriminate proteins of similar structure (HSA and BSA) and reflect the transitions of protein conformation.

Research paper thumbnail of The impact of binding of macrocyclic metal complexes on amyloid fibrillization of insulin and lysozyme

Journal of Molecular Recognition

Research paper thumbnail of β-ketoenole dyes: Synthesis and study as fluorescent sensors for protein amyloid aggregates

Dyes and Pigments, 2016

The series of the new β-ketoenole dyes ((2E,5Z,7E,9E)-6-hydroxy-2-(alkylamino)-10-phenyldeca-2,5,... more The series of the new β-ketoenole dyes ((2E,5Z,7E,9E)-6-hydroxy-2-(alkylamino)-10-phenyldeca-2,5,7,9-tetraen-4-ones) with variation of alkylamino tail groups was synthesized and studied as potential probes for the sensing of protein aggregates amyloid fibrils. The dyes are low fluorescent when free but able to increase their emission intensity in dozens of times in the presence of fibrillar insulin. The fluorescent response of the dye on fibrillar insulin strongly depends on the nature of the alkylamino tail group. For compounds with propylamino (dye 13) and 2-hydroxyethylamino (dye 14) fragments the fluorescence intensity in the presence of fibrillar insulin exceeds that for the native one in 22 and 66 times correspondingly. However dyes demonstrate from low or moderate exceed of the fluorescence intensity in the presence of aggregated lysozyme compared to native one (up to 8.7 times for the dye 53 bearing methyl ester tail group), due to their pronounced sensitivity to native lysozyme. The dyes in complexes with insulin have rather height quantum yield up to 0.15, the large Stokes shifts values (about 100 nm and more), their binding constant values are about 10 5 M-1. The dye 14 allows fluorescent detection of the insulin amyloid fibrils in the concentration range 1-50 μg/ml. This causes an interest in the future study of the β-ketoenole as prospective fluorescent amyloid-sensitive molecules.

Research paper thumbnail of Detection of Polyamino Acids Using Trimethincyanine Dyes

Research paper thumbnail of Use of Squaraine Dyes to Visualize Protein During Separations

Research paper thumbnail of Novel dyes and compositions, and processes for using same in analysis of protein aggregation and other applications

Research paper thumbnail of Dyes for analysis of protein aggregation

Research paper thumbnail of Temperature Dependence of Photoluminescence from Silver Nanoparticles

Research paper thumbnail of Sensing the temperature influence on plasmonic field of metal nanoparticles by photoluminescence of fullerene C60 in layered C60/Au system Sensing the temperature influence on plasmonic field of metal nanoparticles by photoluminescence of fullerene C 60 in layered C 60 /Au system

Journal of Applied Physics

Influence of temperature on the plasmonic field in the temperature range of 78–278 K was studied ... more Influence of temperature on the plasmonic field in the temperature range of 78–278 K was studied employing surface plasmon enhanced photoluminescence from the fullerene C60 thin film deposited on 2D array of Au nanoparticles. It was experimentally found that temperature dependence of plasmonic enhancement factor of C60 luminescence decreases monotonically with the temperature increase. Influence of temperature on plasmonic enhancement factor was found to be considerably stronger when the frequency of surface plasmon absorption band of Au nanoparticles and the frequency of fullerene luminescence band are in resonance. Electron-phonon scattering and thermal expansion of Au nanoparticles were considered as two competing physical mechanisms of the temperature dependence of plasmonic field magnitude. The calculations revealed significant prevalence of the electron-phonon scattering. The temperature induced increase in the scattering rate leads to higher plasmon damping that causes the de...

Research paper thumbnail of Photoluminescence of rhodamine 6G in plasmonic field of Au nanoparticles: Temperature effects

Influence of temperature on the photoluminescence of rhodamine 6G deposited on 2D array of the go... more Influence of temperature on the photoluminescence of rhodamine 6G deposited on 2D array of the gold nanoparticles was studied in the temperature range of 78-278 K. The factor of surface plasmonic enhancement of rhodamine luminescence was found to decrease monotonically with increasing temperature. Electron-phonon scattering and thermal expansion of the gold nanoparticles were considered as two competing physical mechanisms of the temperature dependence of plasmonic enhancement factor. The calculations showed the significant prevalence of the electron-phonon scattering. The temperature induced increase of the scattering rate leads to higher plasmon damping that causes the decrease of plasmonic enhancement of rhodamine 6G luminescence.

Research paper thumbnail of Interaction of the Iron(II) Cage Complexes With Proteins: Protein Fluorescence Quenching Study

Journal of Fluorescence, 2013

Interaction of the iron(II) mono-and bisclathrochelates with bovine serum albumin (BSA), β-lactog... more Interaction of the iron(II) mono-and bisclathrochelates with bovine serum albumin (BSA), β-lactoglobulin, lysozyme and insulin was studied by the steady-state and time-resolved fluorescent spectroscopies. These cage complexes do not make significant impact on fluorescent properties of β-lactoglobulin, lysozyme and insulin. At the same time, the monoclathrochelates strongly quench a fluorescence intensity of BSA and substantially decrease its excited state lifetime due to their binding to this protein. This occurs due to the excitation energy transfer from a tryptophan residue to a cage molecule or/and to the change of the tryptophan nearest environment caused by either clathrochelate binding or an alteration of the BSA conformation. The effect of the iron(II) bis-clathrochelate on BSA fluorescence is much weaker as compared to its monomacrobicyclic analogs as a result of an increase in its size.