Ricardas Rotomskis - Academia.edu (original) (raw)
Papers by Ricardas Rotomskis
Proceedings of SPIE, Jul 17, 1994
ABSTRACT
Journal of Biomedical Optics, Feb 11, 2015
This study combines several fluorescence detection methods to distinguish structural features of ... more This study combines several fluorescence detection methods to distinguish structural features of the synovium and cartilage tissues and to visualize the localization of endogenous porphyrins in the sensitized tissues. Specimens of synovium and cartilage tissues obtained from rabbits with antigen-induced monoarthritis after intra-articular 5-aminolevulinic acid methyl ester injection and those from healthy rabbits were investigated ex vivo by means of fluorescence spectroscopy, fluorescence intensity, and lifetime microscopy. The presence of endogenous porphyrins was confirmed with the fluorescence spectra measured on sliced sensitized specimens. Application of the lifetime-gating method on fast fluorescence lifetime imaging microscopy images, allowed separate visualization of tissue structures possessing different average lifetimes. The presence of the structures has been validated by histopathological imaging based on conventional rapid hematoxylineosin staining of the specimens. The fluorescence lifetime of endogenous protoporphyrin IX has been assessed and employed for visualization of sensitized tissues.
Abstract The penetration of semiconductor quantum dots (QDs) through the stratum corneum and thei... more Abstract The penetration of semiconductor quantum dots (QDs) through the stratum corneum and their subsequent distribution in the skin are important issues for developing nanoparticle-based drug delivery systems and also for nanotoxicology, as the number of nanoparticle-based commercial products is increasing. Knowledge about how QDs with a biologically inert polyethylene glycol (PEG) coating are distributed in the skin, and their subsequent migration pathways after subcutaneous injection and topical application, is crucial for the assessment of the beneficial or harmful behavior of nanoparticles in vivo. Investigation by means of fluorescence microscopy and spectroscopy reveals that QD diffusion in the dermis is limited by the basement membrane and dense connective tissue fibers, resulting in negligible QD penetration to the epidermis, hair follicles, sebaceous and sweat glands, nerves, and blood vessels. QDs are prevented from passing through the densely organized fibrils of the connective tissue coating in the peripheral nerves, blood vessel walls, and muscle fascicles. QDs are endocytosed by the dermal cells. In general, the current study reveals the details of the tissue architecture for the retention and migration patterns of interstitial QDs, which were poorly understood up to now.
International Journal of Molecular Sciences, Mar 30, 2016
Accumulation of carboxylated polyethylene glycol (PEG) CdSe/ZnSquantum dots (QDs) has been monito... more Accumulation of carboxylated polyethylene glycol (PEG) CdSe/ZnSquantum dots (QDs) has been monitored in living fibroblasts using confocal microscopy for fluorescence intensity and fluorescence-lifetime imaging (FLIM). The wide range of mean photoluminescence (PL) lifetime values was observed for the intracellular QDs in different intracellular microenvironment, which revealed structural heterogeneity of endosomes and enabled the distinguishing among endosomes of different maturity.
Sensors, Dec 2, 2020
The ever-growing demand for fast, cheap, and reliable diagnostic tools for personalised medicine ... more The ever-growing demand for fast, cheap, and reliable diagnostic tools for personalised medicine is encouraging scientists to improve existing technology platforms and to create new methods for the detection and quantification of biomarkers of clinical significance. Simultaneous detection of multiple analytes allows more accurate assessment of changes in biomarker expression and offers the possibility of disease diagnosis at the earliest stages. The concept of multiplexing, where multiple analytes can be detected in a single sample, can be tackled using several types of nanomaterial-based biosensors. Quantum dots are widely used photoluminescent nanoparticles and represent one of the most frequent choices for different multiplex systems. However, nanoparticles that incorporate gold, silver, and rare earth metals with their unique optical properties are an emerging perspective in the multiplexing field. In this review, we summarise progress in various nanoparticle applications for multiplexed biomarkers.
Journal of Photochemistry and Photobiology B-biology, Jul 1, 2004
Aqueous solutions of aluminium phthalocyanine tetrasulphonate (AlPcS 4) were investigated by mean... more Aqueous solutions of aluminium phthalocyanine tetrasulphonate (AlPcS 4) were investigated by means of absorption and fluorescence spectroscopy. The absorption spectrum of AlPcS 4 is independent of concentration in a wide range (from 10 À8 to 10 À4 M). The fluorescence spectrum measured with a standard setup is strongly dependent on AlPcS 4 concentration, and the fluorescence maximum is gradually red-shifted with increasing concentration. Calculations that take into account reabsorption of fluorescence (inner-filter effect) fit the experimental observations at low concentrations (up to 10 À6 M). Disagreement between the calculations and spectra recorded at higher concentrations (above 10 À5 M) shows that the reabsorbed light may be reemitted as fluorescence. The influence of inner-filter effects on the spectral shape was demonstrated by the experiments where a fibre-optic front-face fluorescence setup was applied: Under such conditions the shape of the fluorescence spectra for a high concentration (10 À3 M) coincided with that of a low concentration (10 À8 M). In conclusion, the present spectroscopic results show that AlPcS 4 does not form aggregates and is a very stable compound in aqueous solutions.
PubMed, Jun 1, 2004
Aim: Autofluorescence of experimental tumor (hepatoma A22 (MH-A22)) was employed to discriminate ... more Aim: Autofluorescence of experimental tumor (hepatoma A22 (MH-A22)) was employed to discriminate the optical differences between necrotic and non-necrotic tumor, hemorrhagic tumor and healthy tissue. Methods: The experiment was performed ex vivo using the transplantable tumor from the right haunch of hybrid mice (C57Bl/CBA). Blue LED light (lambda em=405 nm) was applied for autofluorescence excitation and fibre optics based spectrofluorimeter was used for spectra detection. Results: We observed that necrotic tumor tissue is characterized by the absence of endogenous porphyrins fluorescence, and registered spectra do not possess differences in the red spectral region (600-710 nm) in comparison with normalized autofluorescence spectra of muscle. Moreover, only certain segments of non-necrotic tumor bear the fluorescence of endogenous porphyrins. Conclusions: Based on the experimental results, we suggest that the absence of long-waved fluorescence differences between necrotic tumor tissue and healthy tissue, e.g. muscle can impede the demarcation between healthy and tumor tissue. The uneven distribution of endogenous porphyrins in non-necrotic tumor tissue as well as the absence of endogenous porphyrins fluorescence in the small experimental tumors complicates the localization of cancerous tissue based on the autofluorescence registration.
Biomedical engineering, Dec 2, 2014
Various organic dyes and nanoparticles are widely investigated due to their potential application... more Various organic dyes and nanoparticles are widely investigated due to their potential application in sensing, imaging, and therapy. Fluorescent nanoparticles (quantum dots, noble metal nanoclusters) have many advantages (excelent photostability, size dependant photoluminescence band, easy surface modification, high two-photon absorbtion cross section) over organic dyes. However these nanomaterials still have some drawbacks which restrict using new methods up to their full potential. Quantum dots (QD) are made up of toxic elements. Noble metal nanoclusters have relatively low photoluminescence quantum yield. These nanoparticles usually absorb and fluoresce in visible spectral region, thus limiting their diagnostics and therapy applications to superficial layers since tissues have high absorption in visible region. Deeper layers of tissue can be achieved by exciting fluorophores in tissue optical window (near infrared (NIR) region), however in this case two photon excitation is needed, which requires very powerful pulsed laser systems (pulse power ~10 8 W), which are very expensive and hard to operate. These disadvantages can be overcome by using upconverting nanoparticles (UCNPs). Upconversion is a process when two or more photons are absorbed in order to generate visible light from NIR excitation. In order to observe upconversion, inexpensive, continuous wave lasers can be used (average power ≤1W or less). Due to their advantages over other fluorophores, such as low toxicity, chemical stability, narrow emission peaks, deeper NIR penetration into biological tissue and tunable optical properties depending on lanthanide dopants in host matrix, UCNPs are promising nanomaterials for imaging cells and tissues [1]. In this study, we have investigated the photostability and spectral properties of water soluble NaYF 4 :Yb 3+ , Er 3+ UCNP's after modification with different phospholipids and their mixtures. We have also studied cytotoxicity and accumulation of UCNP's in NIH3T3 cell line. Materials and methods. Oleate-capped NaYF 4 doped with Yb 3+ (20%), Er 3+ (2%) upconverting nanoparticles were synthesized according to previously reported procedure [2] with slight modifications. We tested two different phospholipids (1,2-Dioleoyl-sn-glycero-3-phosphocholine (DOPC), polyethylene glycol 1,2-dioleoyl-sn-glycero-3-phosphoethanolamine (PEG-DOPE)) and their
Proceedings of SPIE, Mar 1, 1994
ABSTRACT
Ultragarsas, 2008
The impact of ambient humidity on a surface acoustic wave (SAW) propagation in the structure cons... more The impact of ambient humidity on a surface acoustic wave (SAW) propagation in the structure consisting of hematoporphyrin (Hp) film deposited on a piezoelectric lithium niobate substrate has been studied. The SAW transmission dependencies on frequency were measured using an RF network analyzer, and the variation in the SAW velocity was measured using SAW delay-line oscillator technique. The increase in the SAW velocity and decrease in the SAW attenuation with increasing ambient humidity was observed. Both dependencies exhibited exponential dependence on a humidity, and the relative velocity change was proportional to the squared change in the attenuation. This observation is in agreement with the conductivity related mechanism of the humidity impact on the SAW propagation parameters in a hematoporphyrin-lithium niobate structure. The results show that Hp-LiNbO 3 structure can be used as a SAW humidity sensor.
Acta Bio-Optica et Informatica Medica. Inżynieria Biomedyczna, 2004
Acta Bio-Optica et Informatica Medica. Inżynieria Biomedyczna, 2004
PubMed, 2004
The intrinsic autofluorescence properties of biological tissues can change depending on alteratio... more The intrinsic autofluorescence properties of biological tissues can change depending on alterations induced by pathological processes. In this paper, autofluorescence properties of normal and tumor tissue are presented and possibilities of the application of autofluorescence as a parameter for in situ cancer detection in different organs are discussed. Data obtained during in vivo measurements of normal and pigmented skin autofluorescence are presented. Autofluorescence of experimental tumor (hepatoma A22) was measured to discriminate the optical differences between necrotic, non-necrotic and hemorrhagic areas of tumor and healthy tissue. It was concluded that the uneven distribution of endogenous porphyrins fluorescence in non-necrotic tumor tissue as well as the absence of endogenous porphyrins fluorescence in the small experimental tumors complicated the diagnosis of cancerous tissue based on the autofluorescence measurements.
Solid State Phenomena, Apr 1, 2004
An understanding of both the interactions between the adsorbate molecules and the interactions be... more An understanding of both the interactions between the adsorbate molecules and the interactions between adsorbates and the surface is a prerequisite to eventually controlling the selfassembly process in supramolecular aggregation. Here we report the formation of supramolecular structures (J-aggregates) whose size and aggregation pattern are controlled by changing the number of polar sulfonic groups of meso-tetra (4-sulfonatophenyl) porphine. Using atomic force microscopy we show that substituted porphyrin molecules (5,10,15,20-tetrakis(4-sulfonatophenyl) porphine (TPPS4), 5,10,15-tris(4-sulfonatophenyl)-20-phenyl porphine (TPPS3), 5,15-bis(4-sulfonatophenyl)- 10,20-diphenyl porphyne (TPPS2op) - SO3 groups are opposite each other, and 5,20-bis(4- sulfonatophenyl)-10,15-diphenyl porphyne (TPPS2a) . SO3 groups are adjacent each other) form different spatial structures. Our findings suggest that placement of functional groups that are participating in direct noncovalent interactions will allow design and construction of different supramolecular structures adsorbed to surfaces.
Journal of Cancer Research and Clinical Oncology, Sep 3, 1999
New sensitizers for photodynamic therapy (PDT) are reported. These compounds, namely 21-thiaporph... more New sensitizers for photodynamic therapy (PDT) are reported. These compounds, namely 21-thiaporphyrin, 21,23-dithiaporphyrin and 21-oxaporphyrin, reveal some of the properties required for such therapy. Their physicochemical, chemical and pharmacological features meant that we could use them in the treatment of transplantable BFS1 fibrosarcoma in Balb/c mice. New sensitizers and the well-known chlorin e6 (Ce6) were used in doses of 2.5, 5.0, 7.5 and 10.0 mg/kg body weight, given intraperitoneally and followed by light irradiation, the total light doses being 50, 100 and 150 J/cm(2) within 24 h after injection. The effectiveness of new sensitizers in PDT was evaluated with in terms of tumor necrosis intensity, the survival time of treated animals, the rate of tumor response (complete/partial/no response), and skin photosensitivity. These results were compared to results obtained in analogous conditions after Ce6-PDT. Distribution studies revealed that the highest concentration of new compounds occurred within 24 h after injection. The results of these experiments confirmed that 21-thiaporphyrin, 21,23-dithiaporphyrin and 21-oxaporphyrin can be considered as potent tumor photosensitizers that do not exert any unwanted effects, primarily skin photosensitization. We suggest that these porphyrins are possible sensitizers to be applied in clinical PDT.
Photochemical and Photobiological Sciences, Jul 1, 2005
The inflamed synovium of rheumatoid arthritis exhibits many features typical for neoplastic tissu... more The inflamed synovium of rheumatoid arthritis exhibits many features typical for neoplastic tissue implying that the photodynamic therapy might be an efficient modality for chronic poliarthritis. The accumulation of endogenously produced porphyrins after administration of exogenous 5-aminolevulinic acid (ALA) in a rabbit model of rheumatoid arthritis was evaluated by fluorescence spectroscopy. Independent of the way, intravenously or intra-articularly, in which ALA was administered to the experimental animals, the highest fluorescence intensity of endogenously produced porphyrins was detected in the tissues of the inflamed joints. Besides, the application of ALA had a systemic sensitising effect on the whole organism of rabbits. The highest amount of endogenously produced porphyrins in the inflamed joints measured from the surface of the skin above the synovium tissues was detected 1-3 h after the administration of ALA. Fluorescence measurements performed on the tissue specimens ex vivo showed the predominant accumulation of porphyrins in the synovium of the inflamed joints. The fluorescence of porphyrins was also observed in the cartilage tissues taken from knee joints. However, the fluorescence spectra features indicated that the composition of porphyrins detected in the cartilage tissues was different than that in the synovial tissues. The selective accumulation of porphyrins in the inflamed synovial tissues stands up for the application of photodynamic therapy in the treatment of rheumatoid arthritis and implies the possibility to use optical non-invasive methods based on fluorescence detection of endogenously produced porphyrins for diagnostics of inflamed tissues.
Sensors and Actuators B-chemical, Feb 1, 2017
Abstract The impact of ambient air humidity on surface acoustic wave (SAW) propagation in structu... more Abstract The impact of ambient air humidity on surface acoustic wave (SAW) propagation in structures consisting of bovine serum albumin (BSA) and bovine serum albumin - gold nanoclusters (BSA-Au NCs) films deposited on YZ lithium niobate (LiNbO3) substrate has been investigated. The BSA-Au NCs film deposited on the surface of LiNbO3 significantly reduced the low-humidity value of the SAW transmission loss and considerably improved its long-term stability as compared to the BSA film. The amplitude of the output signal of the BSA-Au NCs on LiNbO3 SAW delay line was measured as a function of relative humidity (RH) at the steady-state conditions and as a function of time upon the step-like RH variation. An observed decrease in the transmitted SAW amplitude with increasing RH was explained in terms of the acoustoelectric attenuation. The response and recovery times of the structure with BSA-Au NCs on LiNbO3 SAW delay line upon abrupt humidity changes were on the order of 0.2 s. No impact of RH variation on the SAW propagation was observed in the structures with BSA-Au NCs films deposited on metalized LiNbO3 substrate surface. The time-stable, fast-response and low-loss BSA-Au NCs on LiNbO3 SAW humidity sensor has been applied for monitoring the human respiration by detecting moisture contained in the exhaled air.
Journal of Luminescence, Apr 1, 2003
The energy relaxation kinetics and the structure of the J-aggregates of water-soluble porphyrin 5... more The energy relaxation kinetics and the structure of the J-aggregates of water-soluble porphyrin 5,10,15,20tetrasulphonatophenyl porphine (TPPS 4) were investigated in aqueous medium by means of time-resolved fluorescence spectroscopy and confocal laser-scanning fluorescence microscopy. The excitation of the J-aggregates, at excitation intensities higher than B10 15 photons/cm 2 per pulse, results in a remarkable decrease of the fluorescence quantum yield and in the appearance of an additional, non-exponential energy relaxation channel with a decay constant that depends on the excitation intensity. This relaxation mechanism was attributed to the exciton single-singlet annihilation. The exciton lifetime in the absence of the annihilation was calculated to be B150 ps. Using exciton annihilation theory, the exciton migration within the J-aggregates could be characterized by determining the exciton diffusion constant (1.870.9) 10 À3 cm 2 /s and the hopping time (1.270.6) ps. Using the experimental data, the size of the J-aggregate could be evaluated and was seen to yield at least 20 TPPS 4 molecules per aggregate. It was shown by means of confocal fluorescence laser scanning microscopy that TPPS 4 does self-associate in polyvinyl alcohol (PVA) at acidic pH forming molecular macro-assemblies on a scale of B1 mm in PVA matrices.
Acta Bio-Optica et Informatica Medica. Inżynieria Biomedyczna, 2004
Solid State Phenomena, Apr 1, 2004
The mechanism and conditions of meso-tetra (4-sulfonatophenyl) porphine (TPPS4) molecular aggrega... more The mechanism and conditions of meso-tetra (4-sulfonatophenyl) porphine (TPPS4) molecular aggregate formation and their geometrical structure are investigated by methods of molecular mechanics and quantum chemistry. J- type aggregates are formed of zwitterionic forms of TPPS4via interaction of their positively charged porphyrin rings and negatively charged SO3- groups. According to ab initio and PM3 calculations it was found that TPPS4zwitterion has asymmetrical structure (parts of porphyrin ring are asymmetrically bent out of plane), although the porphyrin ring of TPPS4molecule in neutral aqueous solution (at pH 7) is flat and the planes of phenyl rings are nearly perpendicular to the porphyrin plane. We propose that asymmetrical porphyrin rings are able to form bent threads. The thread is bent approx. 5° for each monomer, so approximately 60 monomers should form the loop (diameter ~20 nm).
Proceedings of SPIE, Jul 17, 1994
ABSTRACT
Journal of Biomedical Optics, Feb 11, 2015
This study combines several fluorescence detection methods to distinguish structural features of ... more This study combines several fluorescence detection methods to distinguish structural features of the synovium and cartilage tissues and to visualize the localization of endogenous porphyrins in the sensitized tissues. Specimens of synovium and cartilage tissues obtained from rabbits with antigen-induced monoarthritis after intra-articular 5-aminolevulinic acid methyl ester injection and those from healthy rabbits were investigated ex vivo by means of fluorescence spectroscopy, fluorescence intensity, and lifetime microscopy. The presence of endogenous porphyrins was confirmed with the fluorescence spectra measured on sliced sensitized specimens. Application of the lifetime-gating method on fast fluorescence lifetime imaging microscopy images, allowed separate visualization of tissue structures possessing different average lifetimes. The presence of the structures has been validated by histopathological imaging based on conventional rapid hematoxylineosin staining of the specimens. The fluorescence lifetime of endogenous protoporphyrin IX has been assessed and employed for visualization of sensitized tissues.
Abstract The penetration of semiconductor quantum dots (QDs) through the stratum corneum and thei... more Abstract The penetration of semiconductor quantum dots (QDs) through the stratum corneum and their subsequent distribution in the skin are important issues for developing nanoparticle-based drug delivery systems and also for nanotoxicology, as the number of nanoparticle-based commercial products is increasing. Knowledge about how QDs with a biologically inert polyethylene glycol (PEG) coating are distributed in the skin, and their subsequent migration pathways after subcutaneous injection and topical application, is crucial for the assessment of the beneficial or harmful behavior of nanoparticles in vivo. Investigation by means of fluorescence microscopy and spectroscopy reveals that QD diffusion in the dermis is limited by the basement membrane and dense connective tissue fibers, resulting in negligible QD penetration to the epidermis, hair follicles, sebaceous and sweat glands, nerves, and blood vessels. QDs are prevented from passing through the densely organized fibrils of the connective tissue coating in the peripheral nerves, blood vessel walls, and muscle fascicles. QDs are endocytosed by the dermal cells. In general, the current study reveals the details of the tissue architecture for the retention and migration patterns of interstitial QDs, which were poorly understood up to now.
International Journal of Molecular Sciences, Mar 30, 2016
Accumulation of carboxylated polyethylene glycol (PEG) CdSe/ZnSquantum dots (QDs) has been monito... more Accumulation of carboxylated polyethylene glycol (PEG) CdSe/ZnSquantum dots (QDs) has been monitored in living fibroblasts using confocal microscopy for fluorescence intensity and fluorescence-lifetime imaging (FLIM). The wide range of mean photoluminescence (PL) lifetime values was observed for the intracellular QDs in different intracellular microenvironment, which revealed structural heterogeneity of endosomes and enabled the distinguishing among endosomes of different maturity.
Sensors, Dec 2, 2020
The ever-growing demand for fast, cheap, and reliable diagnostic tools for personalised medicine ... more The ever-growing demand for fast, cheap, and reliable diagnostic tools for personalised medicine is encouraging scientists to improve existing technology platforms and to create new methods for the detection and quantification of biomarkers of clinical significance. Simultaneous detection of multiple analytes allows more accurate assessment of changes in biomarker expression and offers the possibility of disease diagnosis at the earliest stages. The concept of multiplexing, where multiple analytes can be detected in a single sample, can be tackled using several types of nanomaterial-based biosensors. Quantum dots are widely used photoluminescent nanoparticles and represent one of the most frequent choices for different multiplex systems. However, nanoparticles that incorporate gold, silver, and rare earth metals with their unique optical properties are an emerging perspective in the multiplexing field. In this review, we summarise progress in various nanoparticle applications for multiplexed biomarkers.
Journal of Photochemistry and Photobiology B-biology, Jul 1, 2004
Aqueous solutions of aluminium phthalocyanine tetrasulphonate (AlPcS 4) were investigated by mean... more Aqueous solutions of aluminium phthalocyanine tetrasulphonate (AlPcS 4) were investigated by means of absorption and fluorescence spectroscopy. The absorption spectrum of AlPcS 4 is independent of concentration in a wide range (from 10 À8 to 10 À4 M). The fluorescence spectrum measured with a standard setup is strongly dependent on AlPcS 4 concentration, and the fluorescence maximum is gradually red-shifted with increasing concentration. Calculations that take into account reabsorption of fluorescence (inner-filter effect) fit the experimental observations at low concentrations (up to 10 À6 M). Disagreement between the calculations and spectra recorded at higher concentrations (above 10 À5 M) shows that the reabsorbed light may be reemitted as fluorescence. The influence of inner-filter effects on the spectral shape was demonstrated by the experiments where a fibre-optic front-face fluorescence setup was applied: Under such conditions the shape of the fluorescence spectra for a high concentration (10 À3 M) coincided with that of a low concentration (10 À8 M). In conclusion, the present spectroscopic results show that AlPcS 4 does not form aggregates and is a very stable compound in aqueous solutions.
PubMed, Jun 1, 2004
Aim: Autofluorescence of experimental tumor (hepatoma A22 (MH-A22)) was employed to discriminate ... more Aim: Autofluorescence of experimental tumor (hepatoma A22 (MH-A22)) was employed to discriminate the optical differences between necrotic and non-necrotic tumor, hemorrhagic tumor and healthy tissue. Methods: The experiment was performed ex vivo using the transplantable tumor from the right haunch of hybrid mice (C57Bl/CBA). Blue LED light (lambda em=405 nm) was applied for autofluorescence excitation and fibre optics based spectrofluorimeter was used for spectra detection. Results: We observed that necrotic tumor tissue is characterized by the absence of endogenous porphyrins fluorescence, and registered spectra do not possess differences in the red spectral region (600-710 nm) in comparison with normalized autofluorescence spectra of muscle. Moreover, only certain segments of non-necrotic tumor bear the fluorescence of endogenous porphyrins. Conclusions: Based on the experimental results, we suggest that the absence of long-waved fluorescence differences between necrotic tumor tissue and healthy tissue, e.g. muscle can impede the demarcation between healthy and tumor tissue. The uneven distribution of endogenous porphyrins in non-necrotic tumor tissue as well as the absence of endogenous porphyrins fluorescence in the small experimental tumors complicates the localization of cancerous tissue based on the autofluorescence registration.
Biomedical engineering, Dec 2, 2014
Various organic dyes and nanoparticles are widely investigated due to their potential application... more Various organic dyes and nanoparticles are widely investigated due to their potential application in sensing, imaging, and therapy. Fluorescent nanoparticles (quantum dots, noble metal nanoclusters) have many advantages (excelent photostability, size dependant photoluminescence band, easy surface modification, high two-photon absorbtion cross section) over organic dyes. However these nanomaterials still have some drawbacks which restrict using new methods up to their full potential. Quantum dots (QD) are made up of toxic elements. Noble metal nanoclusters have relatively low photoluminescence quantum yield. These nanoparticles usually absorb and fluoresce in visible spectral region, thus limiting their diagnostics and therapy applications to superficial layers since tissues have high absorption in visible region. Deeper layers of tissue can be achieved by exciting fluorophores in tissue optical window (near infrared (NIR) region), however in this case two photon excitation is needed, which requires very powerful pulsed laser systems (pulse power ~10 8 W), which are very expensive and hard to operate. These disadvantages can be overcome by using upconverting nanoparticles (UCNPs). Upconversion is a process when two or more photons are absorbed in order to generate visible light from NIR excitation. In order to observe upconversion, inexpensive, continuous wave lasers can be used (average power ≤1W or less). Due to their advantages over other fluorophores, such as low toxicity, chemical stability, narrow emission peaks, deeper NIR penetration into biological tissue and tunable optical properties depending on lanthanide dopants in host matrix, UCNPs are promising nanomaterials for imaging cells and tissues [1]. In this study, we have investigated the photostability and spectral properties of water soluble NaYF 4 :Yb 3+ , Er 3+ UCNP's after modification with different phospholipids and their mixtures. We have also studied cytotoxicity and accumulation of UCNP's in NIH3T3 cell line. Materials and methods. Oleate-capped NaYF 4 doped with Yb 3+ (20%), Er 3+ (2%) upconverting nanoparticles were synthesized according to previously reported procedure [2] with slight modifications. We tested two different phospholipids (1,2-Dioleoyl-sn-glycero-3-phosphocholine (DOPC), polyethylene glycol 1,2-dioleoyl-sn-glycero-3-phosphoethanolamine (PEG-DOPE)) and their
Proceedings of SPIE, Mar 1, 1994
ABSTRACT
Ultragarsas, 2008
The impact of ambient humidity on a surface acoustic wave (SAW) propagation in the structure cons... more The impact of ambient humidity on a surface acoustic wave (SAW) propagation in the structure consisting of hematoporphyrin (Hp) film deposited on a piezoelectric lithium niobate substrate has been studied. The SAW transmission dependencies on frequency were measured using an RF network analyzer, and the variation in the SAW velocity was measured using SAW delay-line oscillator technique. The increase in the SAW velocity and decrease in the SAW attenuation with increasing ambient humidity was observed. Both dependencies exhibited exponential dependence on a humidity, and the relative velocity change was proportional to the squared change in the attenuation. This observation is in agreement with the conductivity related mechanism of the humidity impact on the SAW propagation parameters in a hematoporphyrin-lithium niobate structure. The results show that Hp-LiNbO 3 structure can be used as a SAW humidity sensor.
Acta Bio-Optica et Informatica Medica. Inżynieria Biomedyczna, 2004
Acta Bio-Optica et Informatica Medica. Inżynieria Biomedyczna, 2004
PubMed, 2004
The intrinsic autofluorescence properties of biological tissues can change depending on alteratio... more The intrinsic autofluorescence properties of biological tissues can change depending on alterations induced by pathological processes. In this paper, autofluorescence properties of normal and tumor tissue are presented and possibilities of the application of autofluorescence as a parameter for in situ cancer detection in different organs are discussed. Data obtained during in vivo measurements of normal and pigmented skin autofluorescence are presented. Autofluorescence of experimental tumor (hepatoma A22) was measured to discriminate the optical differences between necrotic, non-necrotic and hemorrhagic areas of tumor and healthy tissue. It was concluded that the uneven distribution of endogenous porphyrins fluorescence in non-necrotic tumor tissue as well as the absence of endogenous porphyrins fluorescence in the small experimental tumors complicated the diagnosis of cancerous tissue based on the autofluorescence measurements.
Solid State Phenomena, Apr 1, 2004
An understanding of both the interactions between the adsorbate molecules and the interactions be... more An understanding of both the interactions between the adsorbate molecules and the interactions between adsorbates and the surface is a prerequisite to eventually controlling the selfassembly process in supramolecular aggregation. Here we report the formation of supramolecular structures (J-aggregates) whose size and aggregation pattern are controlled by changing the number of polar sulfonic groups of meso-tetra (4-sulfonatophenyl) porphine. Using atomic force microscopy we show that substituted porphyrin molecules (5,10,15,20-tetrakis(4-sulfonatophenyl) porphine (TPPS4), 5,10,15-tris(4-sulfonatophenyl)-20-phenyl porphine (TPPS3), 5,15-bis(4-sulfonatophenyl)- 10,20-diphenyl porphyne (TPPS2op) - SO3 groups are opposite each other, and 5,20-bis(4- sulfonatophenyl)-10,15-diphenyl porphyne (TPPS2a) . SO3 groups are adjacent each other) form different spatial structures. Our findings suggest that placement of functional groups that are participating in direct noncovalent interactions will allow design and construction of different supramolecular structures adsorbed to surfaces.
Journal of Cancer Research and Clinical Oncology, Sep 3, 1999
New sensitizers for photodynamic therapy (PDT) are reported. These compounds, namely 21-thiaporph... more New sensitizers for photodynamic therapy (PDT) are reported. These compounds, namely 21-thiaporphyrin, 21,23-dithiaporphyrin and 21-oxaporphyrin, reveal some of the properties required for such therapy. Their physicochemical, chemical and pharmacological features meant that we could use them in the treatment of transplantable BFS1 fibrosarcoma in Balb/c mice. New sensitizers and the well-known chlorin e6 (Ce6) were used in doses of 2.5, 5.0, 7.5 and 10.0 mg/kg body weight, given intraperitoneally and followed by light irradiation, the total light doses being 50, 100 and 150 J/cm(2) within 24 h after injection. The effectiveness of new sensitizers in PDT was evaluated with in terms of tumor necrosis intensity, the survival time of treated animals, the rate of tumor response (complete/partial/no response), and skin photosensitivity. These results were compared to results obtained in analogous conditions after Ce6-PDT. Distribution studies revealed that the highest concentration of new compounds occurred within 24 h after injection. The results of these experiments confirmed that 21-thiaporphyrin, 21,23-dithiaporphyrin and 21-oxaporphyrin can be considered as potent tumor photosensitizers that do not exert any unwanted effects, primarily skin photosensitization. We suggest that these porphyrins are possible sensitizers to be applied in clinical PDT.
Photochemical and Photobiological Sciences, Jul 1, 2005
The inflamed synovium of rheumatoid arthritis exhibits many features typical for neoplastic tissu... more The inflamed synovium of rheumatoid arthritis exhibits many features typical for neoplastic tissue implying that the photodynamic therapy might be an efficient modality for chronic poliarthritis. The accumulation of endogenously produced porphyrins after administration of exogenous 5-aminolevulinic acid (ALA) in a rabbit model of rheumatoid arthritis was evaluated by fluorescence spectroscopy. Independent of the way, intravenously or intra-articularly, in which ALA was administered to the experimental animals, the highest fluorescence intensity of endogenously produced porphyrins was detected in the tissues of the inflamed joints. Besides, the application of ALA had a systemic sensitising effect on the whole organism of rabbits. The highest amount of endogenously produced porphyrins in the inflamed joints measured from the surface of the skin above the synovium tissues was detected 1-3 h after the administration of ALA. Fluorescence measurements performed on the tissue specimens ex vivo showed the predominant accumulation of porphyrins in the synovium of the inflamed joints. The fluorescence of porphyrins was also observed in the cartilage tissues taken from knee joints. However, the fluorescence spectra features indicated that the composition of porphyrins detected in the cartilage tissues was different than that in the synovial tissues. The selective accumulation of porphyrins in the inflamed synovial tissues stands up for the application of photodynamic therapy in the treatment of rheumatoid arthritis and implies the possibility to use optical non-invasive methods based on fluorescence detection of endogenously produced porphyrins for diagnostics of inflamed tissues.
Sensors and Actuators B-chemical, Feb 1, 2017
Abstract The impact of ambient air humidity on surface acoustic wave (SAW) propagation in structu... more Abstract The impact of ambient air humidity on surface acoustic wave (SAW) propagation in structures consisting of bovine serum albumin (BSA) and bovine serum albumin - gold nanoclusters (BSA-Au NCs) films deposited on YZ lithium niobate (LiNbO3) substrate has been investigated. The BSA-Au NCs film deposited on the surface of LiNbO3 significantly reduced the low-humidity value of the SAW transmission loss and considerably improved its long-term stability as compared to the BSA film. The amplitude of the output signal of the BSA-Au NCs on LiNbO3 SAW delay line was measured as a function of relative humidity (RH) at the steady-state conditions and as a function of time upon the step-like RH variation. An observed decrease in the transmitted SAW amplitude with increasing RH was explained in terms of the acoustoelectric attenuation. The response and recovery times of the structure with BSA-Au NCs on LiNbO3 SAW delay line upon abrupt humidity changes were on the order of 0.2 s. No impact of RH variation on the SAW propagation was observed in the structures with BSA-Au NCs films deposited on metalized LiNbO3 substrate surface. The time-stable, fast-response and low-loss BSA-Au NCs on LiNbO3 SAW humidity sensor has been applied for monitoring the human respiration by detecting moisture contained in the exhaled air.
Journal of Luminescence, Apr 1, 2003
The energy relaxation kinetics and the structure of the J-aggregates of water-soluble porphyrin 5... more The energy relaxation kinetics and the structure of the J-aggregates of water-soluble porphyrin 5,10,15,20tetrasulphonatophenyl porphine (TPPS 4) were investigated in aqueous medium by means of time-resolved fluorescence spectroscopy and confocal laser-scanning fluorescence microscopy. The excitation of the J-aggregates, at excitation intensities higher than B10 15 photons/cm 2 per pulse, results in a remarkable decrease of the fluorescence quantum yield and in the appearance of an additional, non-exponential energy relaxation channel with a decay constant that depends on the excitation intensity. This relaxation mechanism was attributed to the exciton single-singlet annihilation. The exciton lifetime in the absence of the annihilation was calculated to be B150 ps. Using exciton annihilation theory, the exciton migration within the J-aggregates could be characterized by determining the exciton diffusion constant (1.870.9) 10 À3 cm 2 /s and the hopping time (1.270.6) ps. Using the experimental data, the size of the J-aggregate could be evaluated and was seen to yield at least 20 TPPS 4 molecules per aggregate. It was shown by means of confocal fluorescence laser scanning microscopy that TPPS 4 does self-associate in polyvinyl alcohol (PVA) at acidic pH forming molecular macro-assemblies on a scale of B1 mm in PVA matrices.
Acta Bio-Optica et Informatica Medica. Inżynieria Biomedyczna, 2004
Solid State Phenomena, Apr 1, 2004
The mechanism and conditions of meso-tetra (4-sulfonatophenyl) porphine (TPPS4) molecular aggrega... more The mechanism and conditions of meso-tetra (4-sulfonatophenyl) porphine (TPPS4) molecular aggregate formation and their geometrical structure are investigated by methods of molecular mechanics and quantum chemistry. J- type aggregates are formed of zwitterionic forms of TPPS4via interaction of their positively charged porphyrin rings and negatively charged SO3- groups. According to ab initio and PM3 calculations it was found that TPPS4zwitterion has asymmetrical structure (parts of porphyrin ring are asymmetrically bent out of plane), although the porphyrin ring of TPPS4molecule in neutral aqueous solution (at pH 7) is flat and the planes of phenyl rings are nearly perpendicular to the porphyrin plane. We propose that asymmetrical porphyrin rings are able to form bent threads. The thread is bent approx. 5° for each monomer, so approximately 60 monomers should form the loop (diameter ~20 nm).