Photosensitized production of superoxide anion by monochromatic (290-405 nm) ultraviolet irradiation of NADH and NADPH coenzymes

Photothermal Excitation of Neurons Using MXene: Cellular Stress and Phototoxicity Evaluation

Understanding the communication of individual neurons necessitates precise control of neural activity. Photothermal modulation is a remote and non-genetic technique to control neural activity with high spatiotemporal resolution. The local heat release by photothermally active nanomaterial will change the membrane properties of the interfaced neurons during light illumination. Recently, it is demonstrated that the two-dimensional Ti3 C2 Tx MXene is an outstanding candidate to photothermally excite neurons with low incident energy. However, the safety of using Ti3 C2 Tx for neural modulation is unknown. Here, the biosafety of Ti3 C2 Tx -based photothermal modulation is thoroughly investigated, including assessments of plasma membrane integrity, mitochondrial stress, and oxidative stress. It is demonstrated that culturing neurons on 25 µg cm-2 Ti3 C2 Tx films and illuminating them with laser pulses (635 nm) with different incident energies (2-10 µJ per pulse) and different pulse frequencies (1 pulse, 1 Hz, and 10 Hz) neither damage the cell membrane, induce cellular stress, nor generate oxidative stress. The threshold energy to cause damage (i.e., 14 µJ per pulse) exceeded the incident energy for neural excitation (<10 µJ per pulse). This multi-assay safety evaluation provides crucial insights for guiding the establishment of light conditions and protocols in the clinical translation of photothermal modulation.

KDM1A inhibition increases UVA toxicity and enhances photodynamic therapy efficacy

BACKGROUND

Lysine-specific histone demethylase 1 (KDM1A/LSD1) regulates multiple cellular functions, including cellular proliferation, differentiation, and DNA repair. KDM1A is overexpressed in squamous cell carcinoma of the skin and inhibition of KDM1A can suppress cutaneous carcinogenesis. Despite the role of KDM1A in skin and DNA repair, the effect of KDM1A inhibition on cellular ultraviolet (UV) response has not been studied.

METHODS

The ability of KDM1A inhibitor bizine to modify cell death after UVA and UVB exposure was tested in normal human keratinocytes and melanocytes, HaCaT, and FaDu cell lines. KDM1A was also downregulated using shRNA and inhibited by phenelzine in HaCaT and FaDu cells to confirm the role of KDM1A in UVA response. In addition, cellular reactive oxygen species (ROS) changes were assessed by a lipid-soluble fluorescent indicator of lipid oxidation, and ROS-related gene regulation using qPCR. During photodynamic therapy (PDT) studies HaCaT and FaDu cells were treated with aminolaevulinic acid (5-ALA) or HPPH (2-[1-hexyloxyethyl]-2-devinyl pyropheophorbide-a) sodium and irradiated with 0-8 J/cm2 red LED light.

RESULTS

KDM1A inhibition sensitized cells to UVA radiation-induced cell death but not to UVB. KDM1A inhibition increased ROS generation as detected by increased lipid peroxidation and the upregulation of ROS-responsive genes. The effectiveness of both ALA and HPPH PDT significantly improved in vitro in HaCaT and FaDu cells after KDM1A inhibition.

CONCLUSION

KDM1A is a regulator of cellular UV response and KDM1A inhibition can improve PDT efficacy.

ROS-Scavenging Therapeutic Hydrogels for Modulation of the Inflammatory Response

Although reactive oxygen species (ROS) are essential for cellular processes, excessive ROS could be a major cause of various inflammatory diseases because of the oxidation of proteins, DNA, and membrane lipids. It has recently been suggested that the amount of ROS could thus be regulated to treat such physiological disorders. A ROS-scavenging hydrogel is a promising candidate for therapeutic applications because of its high biocompatibility, 3D matrix, and ability to be modified. Approaches to conferring antioxidant properties to normal hydrogels include embedding ROS-scavenging catalytic nanoparticles, modifying hydrogel polymer chains with ROS-adsorbing organic moieties, and incorporating ROS-labile linkers in polymer backbones. Such therapeutic hydrogels can be used for wound healing, cardiovascular diseases, bone repair, ocular diseases, and neurodegenerative disorders. ROS-scavenging hydrogels could eliminate oxidative stress, accelerate the regeneration process, and show synergetic effects with other drugs or therapeutic molecules. In this review, the mechanisms by which ROS are generated and scavenged in the body are outlined, and the effects of high levels of ROS and the resulting oxidative stress on inflammatory diseases are described. Next, the mechanism of ROS scavenging by hydrogels is explained depending on the ROS-scavenging agents embedded within the hydrogel. Lastly, the recent achievements in the development of ROS-scavenging hydrogels to treat various inflammation-associated diseases are presented.

Acceleration of age-induced proteolysis in the guinea pig lens nucleus by in vivo exposure to hyperbaric oxygen: A mass spectrometry analysis

Hyperbaric oxygen (HBO) treatment of animals or ocular lenses in culture recapitulates many molecular changes observed in human age-related nuclear cataract. The guinea pig HBO model has been one of the best examples of such treatment leading to dose-dependent development of lens nuclear opacities. In this study, complimentary mass spectrometry methods were employed to examine protein truncation after HBO treatment of aged guinea pigs. Quantitative liquid chromatography-mass spectrometry (LC-MS) analysis of the membrane fraction of guinea pig lenses showed statistically significant increases in aquaporin-0 (AQP0) C-terminal truncation, consistent with previous reports of accelerated loss of membrane and cytoskeletal proteins. In addition, imaging mass spectrometry (IMS) analysis spatially mapped the acceleration of age-related αA-crystallin truncation in the lens nucleus. The truncation sites in αA-crystallin closely match those observed in human lenses with age. Taken together, our results suggest that HBO accelerates the normal lens aging process and leads to nuclear cataract.

Photoinactivation results of Enterococcus moraviensis with blue and violet light suggest the involvement of an unconsidered photosensitizer

Microorganisms can be photoinactivated with 405 and 450 nm irradiation, due to endogenous photosensitizers, which absorb light of these wavelengths and generate reactive oxygen species that destroy the cells from within. The photosensitizers assumed to be responsible are porphyrins in the spectral region around 405 nm and flavins at about 450 nm. The aim of this study was to investigate this hypothesis on enterococci, considering that they do not contain porphyrins. In photoinactivation experiments with Enterococcus moraviensis, 405 nm and 450 nm irradiation both led to a reduction of the bacterial concentration by several orders of magnitude with 405 nm irradiation being much more efficient. The measurement and analysis of the fluorescence spectra revealed no signs of porphyrins whereas flavins seemed to be rapidly converted to lumichrome by 405 nm radiation. Therefore, probably none of the usual suspects, porphyrins and flavins, was responsible for the photoinactivation of Enterococcus moraviensis during 405 nm irradiation. Fluorescence experiments revealed the spectra of lumichrome and NADH, which are both known photosensitizers. Presumably, one of them or both were actually involved here. As NADH and flavins (and therefore their photodegradation product lumichrome) are abundant in all microorganisms, they are probably also involved in 405 nm photoinactivation processes of other species.

Between life and death: strategies to reduce phototoxicity in super-resolution microscopy

Super-resolution microscopy (SRM) enables non-invasive, molecule-specific imaging of the internal structure and dynamics of cells with sub-diffraction limit spatial resolution. One of its major limitations is the requirement for high-intensity illumination, generating considerable cellular phototoxicity. This factor considerably limits the capacity for live-cell observations, particularly for extended periods of time. Here, we give an overview of new developments in hardware, software and probe chemistry aiming to reduce phototoxicity. Additionally, we discuss how the choice of biological model and sample environment impacts the capacity for live-cell observations.

Structural and functional alteration of human αA-crystallin after exposure to full spectrum solar radiation and preventive role of lens antioxidants

The chronically exposure of eye lenses to ultra violet and visible light of the solar radiation is an important risk factor for development of the senile cataract diseases. Various photosensitizer molecules including riboflavin (RF) play a significant role in photo-oxidative damages of lens proteins underlying development of opacity in the lenticular tissues. In the current study, RF-mediated photo-oxidation of human αA-crystallin (αA-Cry) was assessed using SDS-PAGE analysis, dynamic light scattering and other spectroscopic assessments. The RF-photosensitized reactions led to non-disulfide covalent cross-linking, oligomerization and significant structural changes in αA-Cry. The photo-damaging of αA-Cry under solar radiation was also accompanied by the reduction in both Trp and Tyr fluorescence intensities which followed by the formation of new photosensitizer chromophores. The solvent exposed hydrophobic patches, secondary structures and chaperone-like activity of αA-Cry were significantly altered after exposure to the solar radiation in the presence of RF. Although glutathione and ascorbate were capable to partially protect the photo-induced structural damages of human αA-Cry, they also disrupted its chaperone function when co-exposed with this protein to the solar radiation. Also, the most promising data were obtained with cysteine which its availability in the lenticular tissues is a rate limiting factor for the biosynthesis of glutathione. Overall our results suggest that glutathione and ascorbate, as the major anti-oxidant compounds within lenticular tissues, demonstrate controversial effect on structure and chaperone-like activity of human αA-Cry. Elucidation of this effect may demand further experiments.

Blue light exposure decreases systolic blood pressure, arterial stiffness, and improves endothelial function in humans

AIMS

Previous studies have shown that ultraviolet light can lead to the release of nitric oxide from the skin and decrease blood pressure. In contrast to visible light the local application of ultraviolet light bears a cancerogenic risk. Here, we investigated whether whole body exposure to visible blue light can also decrease blood pressure and increase endothelial function in healthy subjects.

METHODS

In a randomised crossover study, 14 healthy male subjects were exposed on 2 days to monochromatic blue light or blue light with a filter foil (control light) over 30 minutes. We measured blood pressure (primary endpoint), heart rate, forearm vascular resistance, forearm blood flow, endothelial function (flow-mediated dilation), pulse wave velocity and plasma nitric oxide species, nitrite and nitroso compounds (secondary endpoints) during and up to 2 hours after exposure.

RESULTS

Blue light exposure significantly decreased systolic blood pressure and increased heart rate as compared to control. In parallel, blue light significantly increased forearm blood flow, flow-mediated dilation, circulating nitric oxide species and nitroso compounds while it decreased forearm vascular resistance and pulse wave velocity.

CONCLUSION

Whole body irradiation with visible blue light at real world doses improves blood pressure, endothelial function and arterial stiffness by nitric oxide released from photolabile intracutanous nitric oxide metabolites into circulating blood.

Confined photo-release of nitric oxide with simultaneous two-photon fluorescence tracking in a cellular system

Nitric oxide (NO) is a key signaling molecule in biological systems. New tools are required to therapeutically modulate NO levels with confined precision. This study explores the photoactivatable properties of an NO releasing compound (CPA), based on cupferron O-alkylated with an anthracene derivative. Upon light stimulation, CPA uncages two species: cupferron, which liberates NO, and an anthrylmethyl carbocation, which evolves into a fluorescent reporter. Proof-of-principle is demonstrated using one- and two-photon excitation (1PE and 2PE) in a cellular system (A431 cells). It was found that 1PE induces cell toxicity, while 2PE does not. Since 1PE using UV light is more likely to generate cellular photodamage, the cell toxicity observed using 1PE is most likely a combinatory effect of NO release and other UV-induced damage, which should be subject to further investigation. On the other hand, absence of phototoxicity using 2PE suggests that NO alone is not cytotoxic. This leads to the conclusion that the concept of 2PE photorelease of NO from CPA enable opportunities for biological studies of NO signaling with confined precision of NO release with minimal cytotoxicity.

RGD-modified dihydrolipoamide dehydrogenase conjugated to titanium dioxide nanoparticles –switchableintegrin-targeted photodynamic treatment of melanoma cells

The photocytotoxic effect of UVA-excited titanium dioxide (TiO₂), which is caused by the generation of reactive oxygen species (ROS), is often used in medical applications, such as cancer treatment. Photodynamic-therapy (PDT) is applied in several cancer models including cutaneous melanoma (CM), however the lack of selectivity causing damage to surrounding healthy tissues limits its applicability and novel targeted-delivery approaches are required. As cancer cells often overexpress integrin receptors (e.g. αvβ₃) on their cell surface, targeted delivery of TiO₂ nanoparticles (NPs) via an Arg-Gly-Asp (RGD) motif would make PDT more selective. We have recently reported that the mitochondrial enzyme dihydrolipoamide dehydrogenase (DLDH) strongly and specifically conjugates TiO₂via coordinative bonds. In this work we have modified DLDH with RGD moieties (DLDH^RGD), creating a molecular bridge between the integrin-expressing cancer cells and the photo-excitable TiO₂ nanoparticles. Physicochemical assays have indicated that the hybrid-conjugated nanobiocomplex, TiO₂–DLDH^RGD, is producing controlled-release ROS under UVA illumination, with anatase NPs being the most photoreactive TiO₂ form. This drug delivery system exhibited a cytotoxic effect in αvβ₃ integrin-expressing mice melanoma cells (B16F10), but not in normal cells lacking this integrin (HEK293). No cytotoxic effect was observed in the absence of UV illumination. Our results demonstrate the feasibility of combining the high efficiency of TiO₂-based PDT, with an integrin-mediated tumor-targeted drug delivery for nanomedicine.

This work presents a UVA switchable integrin-targeted photodynamic therapy in melanoma, composed of an RGD-modified DLDH conjugated to TiO₂ nanoparticles, with high selectivity towards integrin-expressing cancer cells.

Mitochondrial selectivity and remarkable photocytotoxicity of a ferrocenyl neodymium(iii) complex of terpyridine and curcumin in cancer cells

A mixed-ligand neodymium(iii) complex of ferrocene appended terpyridine and curcumin targets the mitochondria and shows remarkable visible-light induced cytotoxicity in HeLa and MCF-7 cancer cells while being much less toxic in dark and to MCF-10A normal cells.

A multifunctional, light-activated prochelator inhibits UVA-induced oxidative stress

UVA radiation can damage cells and tissues by direct photodamage of biomolecules as well as by initiating metal-catalyzed oxidative stress. In order to alleviate both concerns simultaneously, we synthesized a multifunctional prochelator PC-HAPI (2-((E)-1-(2-isonicotinoylhydrazono)ethyl)phenyl (trans)-3-(2,4-dihydroxyphenyl)acrylate) that contains a trans-(o-hydroxy)cinnamate ester photocleavable protecting group that is cleaved upon UVA exposure to release a coumarin, umbelliferone, and an aroylhydrazone metal chelator, HAPI (N'-[1-(2-hydroxyphenyl)ethyliden]isonicotinoylhydrazide). While the prochelator PC-HAPI exhibits negligible affinity for iron, it responds rapidly to UVA irradiation and converts to an iron-binding chelator that inhibits iron-catalyzed formation of reactive oxygen species and protects cells from UVA damage.

Oxovanadium(IV) complexes of curcumin for cellular imaging and mitochondria targeted photocytotoxicity

Oxovanadium(IV) complexes [VO(R-tpy)(cur)](ClO4) (1, 2) of curcumin (Hcur) and terpyridine ligands (R-tpy) where R is phenyl (phtpy in 1) or p-triphenylphosphonium methylphenyl bromide (C6H4CH2PPh3Br) (TPP-phtpy in 2) were prepared and characterized and their DNA photocleavage activity, photocytotoxicity and cellular localization in cancer cells (HeLa and MCF-7) were studied. Acetylacetonate (acac) complexes [VO(R-tpy)(acac)](ClO4) of phtpy (3) and TPP-phtpy (4) were prepared and used as the control species. These complexes showed efficient cleavage of pUC19 DNA in visible light of 454 nm and near-IR light of 705 nm. Complexes 1 and 2 showed significant photocytotoxicity in visible light of 400-700 nm. FACS analysis showed sub-G1/G0 phase cell-cycle arrest in cancer cells when treated with 1 and 2 in visible light in comparison with the dark controls. Fluorescence microscopic studies revealed specific localization of the p-triphenylphosphonium complex 2 in the mitochondria of MCF-7 cancer cells whereas no such specificity was observed for complex 1.

Thioredoxin reductase activity may be more important than GSH level in protecting human lens epithelial cells against UVA light

This study compares the abilities of the glutathione (GSH) and thioredoxin (Trx) antioxidant systems in defending cultured human lens epithelial cells (LECs) against UVA light. Levels of GSH were depleted with either L-buthionine-(S,R)-sulfoximine (BSO) or 1-chloro-2,4-dinitrobenzene (CDNB). CDNB treatment also inhibited the activity of thioredoxin reductase (TrxR). Two levels of O2 , 3% and 20%, were employed during a 1 h exposure of the cells to 25 J cm(-2) of UVA radiation (338-400 nm wavelength, peak at 365 nm). Inhibition of TrxR activity by CDNB, combined with exposure to UVA light, produced a substantial loss of LECs and cell damage, with the effects being considerably more severe at 20% O2 compared to 3%. In contrast, depletion of GSH by BSO, combined with exposure to UVA light, produced only a slight cell loss, with no apparent morphological effects. Catalase was highly sensitive to UVA-induced inactivation, but was not essential for protection. Although UVA light presented a challenge for the lens epithelium, it was well tolerated under normal conditions. The results demonstrate an important role for TrxR activity in defending the lens epithelium against UVA light, possibly related to the ability of the Trx system to assist DNA synthesis following UVA-induced cell damage.

BODIPY appended copper(ii) complexes of curcumin showing mitochondria targeted remarkable photocytotoxicity in visible light

BODIPY-appended copper(ii) complexes of curcumin show a remarkable PDT effect in visible light in HeLa cellsviaapoptosis with mitochondrial localization.

Light-independent reactive oxygen species (ROS) formation through electron transfer from carboxylated single-walled carbon nanotubes in water

Promising developments in application of carbon nanotubes (CNTs) have raised concern regarding potential biological and environmental effects upon their inevitable release to the environment. Although some CNTs have been reported to generate reactive oxygen species (ROS) under light, limited information exists on ROS generation by these materials in the dark. In this study, generation of ROS was examined, initiated by electron transfer from biological electron donors through carboxylated single-walled carbon nanotubes (C-SWCNT) to molecular oxygen in water in the dark. In the presence of C-SWCNT, the oxidation of NADH (β-nicotinamide adenine dinucleotide, reduced form) and DTTre (DL-dithiothreitol, reduced form) was confirmed by light absorbance shifts (340 nm to 260 nm during oxidation of NADH to NAD(+), and increased light absorbance at 280 nm during oxidation of DTTre). Production of superoxide anion (O2(•-)) was detected by its selective reaction with a tetrazolium salt (NBT(2+)), forming a formazan product that is visible at 530 nm. A modified acid-quenched N,N-diethyl-p-phenylenediamine (DPD) assay was used to measure the accumulation of H2O2 in C-SWCNT suspensions containing O2 and NADH. In the same suspensions (i.e., containing C-SWCNT, NADH, and O2), pBR322 DNA plasmid was cleaved, although •OH was not detected when using •OH scavenging molecular probes. These results indicate that the oxidation of electron donors by C-SWCNT can be a light-independent source of ROS in water, and that electron shuttling through CNTs to molecular oxygen may be a potential mechanism for DNA damage by this specific CNT and potentially other carbon-based nanomaterials.

Porphyra-334 isolated from the marine algae Bangia atropurpurea: conformational performance for energy conversion

Prophyra-334 (p-334) may play a role of energy transfer under an uncertain mechanism, and we speculate the possible model. Via 1D and 2D NMR experiments, it was simulated the correlation between dissociation and conformation of p-334. Intramolecular interactions were observed based on a series of changes in the 1H and 13C chemical shifts. Nuclear Overhauser effect spectroscopy experiments and molecular models in various pD conditions indicated the p-334 molecular dissociation process status. In addition, we also used Chem3D software to find the most possible molecular conformation. The relationship between the structural status and energy conversion is explained. Those are the primary results. More researches on it are highly expected in the future.

Inactivation of Escherichia coli by polychromatic simulated sunlight: evidence for and implications of a fenton mechanism involving iron, hydrogen peroxide, and superoxide

Sunlight inactivation of Escherichia coli has previously been shown to accelerate in the presence of oxygen, exogenously added hydrogen peroxide, and bioavailable forms of exogenously added iron. In this study, mutants unable to effectively scavenge hydrogen peroxide or superoxide were found to be more sensitive to polychromatic simulated sunlight (without UVB wavelengths) than wild-type cells, while wild-type cells grown under low-iron conditions were less sensitive than cells grown in the presence of abundant iron. Furthermore, prior exposure to simulated sunlight was found to sensitize cells to subsequent hydrogen peroxide exposure in the dark, but this effect was attenuated for cells grown with low iron. Mutants deficient in recombination DNA repair were sensitized to simulated sunlight (without UVB wavelengths), but growth in the presence of iron chelators reduced the degree of sensitization conferred by this mutation. These findings support the hypothesis that hydrogen peroxide, superoxide, and intracellular iron all participate in the photoinactivation of E. coli and further suggest that the inactivation rate of enteric bacteria in the environment may be strongly dependent on iron availability and growth conditions.

Mechanism and biological relevance of blue-light (420-453 nm)-induced nonenzymatic nitric oxide generation from photolabile nitric oxide derivates in human skin in vitro and in vivo

Human skin contains photolabile nitric oxide (NO) derivates such as nitrite and S-nitrosothiols, which upon UVA radiation decompose under high-output NO formation and exert NO-specific biological responses such as increased local blood flow or reduced blood pressure. To avoid the injurious effects of UVA radiation, we here investigated the mechanism and biological relevance of blue-light (420-453 nm)-induced nonenzymatic NO generation from photolabile nitric oxide derivates in human skin in vitro and in vivo. As quantified by chemiluminescence detection (CLD), at physiological pH blue light at 420 or 453 nm induced a significant NO formation from S-nitrosoalbumin and also from aqueous nitrite solutions by a to-date not entirely identified Cu(1+)-dependent mechanism. As detected by electron paramagnetic resonance spectrometry in vitro with human skin specimens, blue light irradiation significantly increased the intradermal levels of free NO. As detected by CLD in vivo in healthy volunteers, irradiation of human skin with blue light induced a significant emanation of NO from the irradiated skin area as well as a significant translocation of NO from the skin surface into the underlying tissue. In parallel, blue light irradiation caused a rapid and significant rise in local cutaneous blood flow as detected noninvasively by using micro-light-guide spectrophotometry. Irradiation of human skin with moderate doses of blue light caused a significant increase in enzyme-independent cutaneous NO formation as well as NO-dependent local biological responses, i.e., increased blood flow. The effects were attributed to blue-light-induced release of NO from cutaneous photolabile NO derivates. Thus, in contrast to UVA, blue-light-induced NO generation might be therapeutically used in the treatment of systemic and local hemodynamic disorders that are based on impaired physiological NO production or bioavailability.

Enhancing the photocytotoxic potential of curcumin on terpyridyl lanthanide(III) complex formation

Lanthanide(III) complexes [Ln(R-tpy)(cur)(NO3)2] (Ln = La(III) in 1, 2; Gd(III) in 5, 6) and [Ln(R-tpy)(scur)(NO3)2] (Ln = La(III) in 3, 4; Gd(III) in 7, 8), where R-tpy is 4′-phenyl-2,2′:6′,2′′-terpyridine (ph-tpy in 1, 3, 5, 7), 4′-(1-pyrenyl)-2,2′:6′,2′′-terpyridine (py-tpy in 2, 4, 6, 8), Hcur is curcumin (in 1, 2, 5, 6) and Hscur is diglucosylcurcumin (in 3, 4, 7, 8), were prepared and their DNA photocleavage activity and photocytotoxicity studied. Complexes [La(ph-tpy)(cur)(NO3)2] (1) and [Gd(ph-tpy)(cur)(NO3)2] (5) were structurally characterized. The complexes in aqueous-DMF showed an absorption band near 430 nm and an emission band near 515 nm when excited at 420 nm. The complexes are moderate binders to calf-thymus DNA. They cleave plasmid supercoiled DNA to its nicked circular form in UV-A (365 nm) and visible light (454 nm) via (1)O2 and ˙OH pathways. The complexes are remarkably photocytotoxic in HeLa cells in visible light (λ = 400–700 nm) and are non-toxic in the dark. FACScan analysis of the HeLa cells treated with 2 and 4 showed cell death via an apoptotic pathway. Nuclear localization of 1–4 is evidenced from confocal imaging on HeLa cells. The hydrolytic instability of curcumin gets significantly reduced upon binding to the lanthanide ions while retaining its photocytotoxic potential.

High resolution fluorescence imaging of cancers using lanthanide ion-doped upconverting nanocrystals

During the last decade inorganic luminescent nanoparticles that emit visible light under near infrared (NIR) excitation (in the biological window) have played a relevant role for high resolution imaging of cancer. Indeed, semiconductor quantum dots (QDs) and metal nanoparticles, mostly gold nanorods (GNRs), are already commercially available for this purpose. In this work we review the role which is being played by a relatively new class of nanoparticles, based on lanthanide ion doped nanocrystals, to target and image cancer cells using upconversion fluorescence microscopy. These nanoparticles are insulating nanocrystals that are usually doped with small percentages of two different rare earth (lanthanide) ions: The excited donor ions (usually Yb3+ ion) that absorb the NIR excitation and the acceptor ions (usually Er3+, Ho3+ or Tm3+), that are responsible for the emitted visible (or also near infrared) radiation. The higher conversion efficiency of these nanoparticles in respect to those based on QDs and GNRs, as well as the almost independent excitation/emission properties from the particle size, make them particularly promising for fluorescence imaging. The different approaches of these novel nanoparticles devoted to "in vitro" and "in vivo" cancer imaging, selective targeting and treatment are examined in this review.

A Class I UV-blocking (senofilcon A) soft contact lens prevents UVA-induced yellow fluorescence and NADH loss in the rabbit lens nucleus in vivo

It is known that fluorescence, much of it caused by UVA light excitation, increases in the aging human lens, resulting in loss of sharp vision. This study used an in vivo animal model to investigate UVA-excited fluorescence in the rabbit lens, which contains a high level of the UVA chromophore NADH, existing both free and bound to λ-crystallin. Also, the ability of a Class I (senofilcon A) soft contact lens to protect against UVA-induced effects on the rabbit lens was tested. Rabbit eyes were irradiated with UVA light in vivo (100 mW/cm(2) on the cornea) for 1 h using monochromatic 365 nm light. Irradiation was conducted in the presence of either a senofilcon A contact lens, a minimally UV-absorbing lotrafilcon A contact lens, or no contact lens at all. Eyes irradiated without a contact lens showed blue 365 nm-excited fluorescence initially, but this changed to intense yellow fluorescence after 1 h. Isolated, previously irradiated lenses exhibited yellow fluorescence originating from the lens nucleus when viewed under 365 nm light, but showed normal blue fluorescence arising from the cortex. Previously irradiated lenses also exhibited a faint yellow color when observed under visible light. The senofilcon A contact lens protected completely against the UVA-induced effects on fluorescence and lens yellowing, whereas the lotrafilcon A lens showed no protection. The UVA-exposure also produced a 53% loss of total NADH (free plus bound) in the lens nucleus, with only a 13% drop in the anterior cortex. NADH loss in the nucleus was completely prevented with use of a senofilcon A contact lens, but no significant protection was observed with a lotrafilcon A lens. Overall, the senofilcon A lens provided an average of 67% protection against UVA-induced loss of four pyridine nucleotides in four different regions of the lens. HPLC analysis with fluorescence detection indicated a nearly six-fold increase in 365 nm-excited yellow fluorescence arising from lens nuclear λ-crystallin after the in vivo UVA exposure. It is concluded that UVA-induced loss of free NADH (which fluoresces blue) may have allowed the natural yellow fluorescence of λ-crystallin and other proteins in the lens nucleus to become visible. Increased fluorescence exhibited by UVA-exposed λ-crystallin may have been the result of a UVA-induced change in the conformation of the protein occurring during the initial UVA-exposure in vivo. The results demonstrate the greater susceptibility of the lens nucleus to UVA-induced stress, and may relate to the formation of human nuclear cataract. The senofilcon A contact lens was shown to be beneficial in protecting the rabbit lens against effects of UVA light, including changes in fluorescence, increased yellowing and loss of pyridine nucleotides.

Light-mediated activation reveals a key role for protein kinase A and sarcoma protein kinase in the development of sperm hyper-activated motility

BACKGROUND

Hyper-activated motility (HAM) is part of the sperm capacitation process, which is necessary for fertilization. In this study, we investigated the effect of visible light on sperm motility and hyperactivation and evaluated pathways mediating these effects.

METHODS

Human sperm (1 × 10⁷ cells/ml) in capacitation media were irradiated for 3 min with 40 mW/cm² visible light (400-800 nm with maximum energy at 600 nm). Sperm motility was assessed and analyzed by computer-assisted sperm analysis. The involvement of sperm capacitation factors was investigated as follows. The generation of reactive oxygen species (ROS) was measured using 20,70-dichlorofluorescein diacetate. Protein kinase A (PKA) and sarcoma protein kinase (Src) activity were measured using western blot analysis and inhibited using 50 µM H89 and 10 µM PP2, respectively. Soluble adenlyl cyclase was inhibited using 20 µM 2-OH-Estradiol. The intracellular concentration of free Ca(2+) was assessed using the fluorescent calcium indicator, Fluo-4/AM. Sperm DNA fragmentation was determined using the sperm chromatin dispersion test.

RESULTS

Light irradiation of human sperm caused a significant increase in hyper-HAM but not total motility. The production of ROS and activation of soluble adenylyl cyclase and PKA mediated the effect of light on HAM. Light irradiation also activated Src, and inhibition of Src significantly reduced the effect of light on HAM. Light irradiation caused a rapid increase in intracellular Ca²⁺ concentration and the increase in HAM was significantly reduced when voltage-dependent-Ca²⁺-channel activity was blocked or when Ca²⁺-deficient medium was used.

CONCLUSIONS

Light irradiation of human sperm for a short time causes a significant increase in HAM in a mechanism mediated by ROS production, activation of PKA, Src and Ca²⁺ influx.

The use of some nanoemulsions based on aqueous propolis and lycopene extract in the skin's protective mechanisms against UVA radiation

BACKGROUND

The use of natural products based on aqueous extract of propolis and lycopene in the skin's protective mechanisms against UVA radiation was evaluated by means of experimental acute inflammation on rat paw edema. The aim of the present study was to evaluate the harmlessness of propolis - lycopene system through evaluation of skin level changes and anti-inflammatory action. The regenerative and protective effect of the aqueous propolis and lycopene extract is based on its richness in biologically active substances such as: tocopherols, flavonoids, amino acids, polyunsaturated fatty acids, the chlorophyll pigment, all substances with strong antioxidant activity, that modify the oxidative stress, mainly by reducing the prooxidant processes and enhancing the antioxidant ones. These substances participate in the synthesis of prostaglandins and phospholipids components of cell membrane thus enhancing skin protection mechanisms.

RESULTS

The experimental systems offered a sustained release of the drug, in vitro, for aim eight hours. The prepared formulations aim did not reveal a deteriorating effect on tissues. They proved a better therapeutic efficiency Compared to standard suspension, they provided a better therapeutic efficiency coupled with extended time interval of tested parameters (24 hours). Preliminary examination of tissues showed that the experimental formulations did not irritate. Local application of propolis and lycopene aqueous extract nanoemulsion has a high potential both regarding its efficiency (the analgesic effect) and therapeutic safety.

CONCLUSIONS

This study demonstrates that propolis and lycopene extract nanoemulsions, preparations contains active substances, can confer better therapeutic effects than those of the conventional formulations, based on local control-release of dozed form, for a longer period of time, which probably improve its efficiency and skin acceptance, meaning a better compliance. The information obtained in the present study suggests that administration of propolis and lycopene aqueous extract nanoemulsion is safe. The preparation can be useful for further preclinical studies lycopene embedded in aqueous propolis extract to be used in pharmaceuticals (targeted medical therapy).

Transient transfection of mammalian cells using a violet diode laser

We demonstrate the first use of the violet diode laser for transient mammalian cell transfection. In contrast to previous studies, which showed the generation of stable cell lines over a few weeks, we develop a methodology to transiently transfect cells with an efficiency of up to approximately 40%. Chinese hamster ovary (CHO-K1) and human embryonic kidney (HEK293) cells are exposed to a tightly focused 405-nm laser in the presence of plasmid DNA encoding for a mitochondrial targeted red fluorescent protein. We report transfection efficiencies as a function of laser power and exposure time for our system. We also show, for the first time, that a continuous wave laser source can be successfully applied to selective gene silencing experiments using small interfering RNA. This work is a major step towards an inexpensive and portable phototransfection system.

Optically controlled thermal management on the nanometer length scale

The manipulation of polymers and biological molecules or the control of chemical reactions on a nanometer scale by means of laser pulses shows great promise for applications in modern nanotechnology, biotechnology, molecular medicine or chemistry. A controllable, parallel, highly efficient and very local heat conversion of the incident laser light into metal nanoparticles without ablation or fragmentation provides the means for a tool like a 'nanoreactor', a 'nanowelder', a 'nanocrystallizer' or a 'nanodesorber'. In this paper we explain theoretically and show experimentally the interaction of laser radiation with gold nanoparticles on a polymethylmethacrylate (PMMA) layer (one-photon excitation) by means of different laser pulse lengths, wavelengths and pulse repetition rates. To the best of our knowledge this is the first report showing the possibility of highly local (in a 40 nm range) regulated heat insertion into the nanoparticle and its surroundings without ablation of the gold nanoparticles. In an earlier paper we showed that near-infrared femtosecond irradiation can cut labeled DNA sequences in metaphase chromosomes below the diffraction-limited spot size. Now, we use gold as well as silver-enhanced gold nanoparticles on DNA (also within chromosomes) as energy coupling objects for femtosecond laser irradiation with single-and two-photon excitation. We show the results of highly localized destruction effects on DNA that occur only nearby the nanoparticles.

The role of corneal crystallins in the cellular defense mechanisms against oxidative stress

The refracton hypothesis describes the lens and cornea together as a functional unit that provides the proper ocular transparent and refractive properties for the basis of normal vision. Similarities between the lens and corneal crystallins also suggest that both elements of the refracton may also contribute to the antioxidant defenses of the entire eye. The cornea is the primary physical barrier against environmental assault to the eye and functions as a dominant filter of UV radiation. It is routinely exposed to reactive oxygen species (ROS)-generating UV light and molecular O(2) making it a target vulnerable to UV-induced damage. The cornea is equipped with several defensive mechanisms to counteract the deleterious effects of UV-induced oxidative damage. These comprise both non-enzymatic elements that include proteins and low molecular weight compounds (ferritin, glutathione, NAD(P)H, ascorbate and alpha-tocopherol) as well as various enzymes (catalase, glucose-6-phosphate dehydrogenase, glutathione peroxidase, glutathione reductase, and superoxide dismutase). Several proteins accumulate in the cornea at unusually high concentrations and have been classified as corneal crystallins based on the analogy of these proteins with the abundant taxon-specific lens crystallins. In addition to performing a structural role related to ocular transparency, corneal crystallins may also contribute to the corneal antioxidant systems through a variety of mechanisms including the direct scavenging of free radicals, the production of NAD(P)H, the metabolism and/or detoxification of toxic compounds (i.e. reactive aldehydes), and the direct absorption of UV radiation. In this review, we extend the discussion of the antioxidant defenses of the cornea to include these highly expressed corneal crystallins and address their specific capacities to minimize oxidative damage.

Reductive DNA cleavage induced by UVA photoirradiation of NADH without oxygen

UVA irradiation of dihydronicotinamide coenzyme (NADH), which plays a key role in a number of biological redox processes, results in effective DNA cleavage without oxygen via photoionization of NADH and the subsequent reaction of hydrated electron with DNA as well as photoinduced electron transfer from NADH to DNA.

DNA cleavage by UVA irradiation of NADH with dioxygen via radical chain processes

Efficient DNA cleaving-activity is observed by UVA irradiation of an O(2)-saturated aqueous solution of NADH (beta-nicotinamide adenine dinucleotide, reduced form). No DNA cleavage has been observed without NADH under otherwise the same experimental conditions. In the presence of NADH, energy transfer from the triplet excited state of NADH ((3)NADH*) to O(2) occurs to produce singlet oxygen ((1)O(2)) that is detected by the phosphorescence emission at 1270 nm. No quenching of (1)O(2) by NADH was observed as indicated by no change in the intensity of phosphorescence emission of (1)O(2) at 1270 nm in the presence of various concentrations of NADH. In addition to the energy transfer, photoinduced electron transfer from (3)NADH* to O(2) occurs to produce NADH(*+) and O(2)(*-), both of which was observed by ESR. The quantum yield of the photochemical oxidation of NADH with O(2) increases linearly with increasing concentration of NADH but decreases with increasing the light intensity absorbed by NADH. Such unusual dependence of the quantum yield on concentration of NADH and the light intensity absorbed by NADH indicates that the photochemical oxidation of NADH with O(2) proceeds via radical chain processes. The O(2)(*-) produced in the photoinduced electron transfer is in the protonation equilibrium with HO(2)(*), which acts as a chain carrier for the radical chain oxidation of NADH with O(2) to produce NAD(+) and H(2)O(2), leading to the DNA cleavage.

Photosensitized DNA damage induced by NADH: site specificity and mechanism

Increasing evidence reveals the carcinogenicity of UVA radiation. We demonstrated that UVA-irradiated NADH induced damage to (32)P-labeled DNA fragments obtained from the p53 gene in the presence of Cu(II). Formamidopyrimidine glycosylase (Fpg)-sensitive lesions were formed at guanine residues, whereas piperidine-labile lesions occurred frequently at thymine residues. Formation of 8-oxo-7,8-dihydro-2'-deoxyguanosine (8-oxodG), upon UVA exposure in the presence of Cu(II), increased depending on NADH concentration. Catalase and bathocuproine, a Cu(I)-specific chelator, inhibited the DNA damage, suggesting the involvement of reactive species derived from H(2)O(2) and Cu(I). UVA-irradiated riboflavin induced DNA cleavage through electron transfer at 5' guanine of the 5'-GG-3' sequence with both Fpg and piperidine treatments; Fpg induced less cleavage at the guanine residues than piperidine. These results imply that NADH may participate as an endogenous photosensitizer in UVA carcinogenesis via H(2)O(2) generation, producing metal-mediated mutagenic lesions such as 8-oxodG.

New photoproducts from irradiation of NADH with near-UV light

Adenosine 5'-diphosphoribose (ADPR) and a second compound, which may be nicotinamide, are the newly discovered photoproducts resulting from irradiation of beta-nicotinamide adenine dinucleotide (beta-NADH) in the wavelength range of 300-400 nm under oxygen-poor conditions. Both products emerge there even exclusively, whereas, at higher oxygen concentrations, the oxidized form of nicotinamide adenine dinucleotide (NAD+) is additionally formed, although still as a minor product. The development of ADPR and NAD+ is clearly oxygen-dependent, while, for the formation of the second photoproduct, small quantities of oxygen appear to be sufficient.

Algae extract-mediated stimulation and protection of proteasome activity within human keratinocytes exposed to UVA and UVB irradiation

Sun exposure is the major environmental influence for epidermal cells; the harmful effect of UV radiation on skin is related to the generation of reactive oxygen species that alter cellular components including proteins. It is now well established that the proteasome is responsible for the degradation of most of oxidized proteins and that impairment of proteasome function is a hallmark of cellular aging. In a previous study, we investigated the effects of UV irradiation on proteasomes in human keratinocyte cultures and showed that all three peptidase activities were decreased 24 h after irradiation of the cells. Increased levels of oxidatively modified proteins were observed in irradiated cells and were found to act as endogenous inhibitors of the proteasome. We report here on the stimulating and protective effects of an algae extract, prepared from Phaeodactylum tricornutum, on proteasome peptidase activities of human keratinocytes exposed to UVA and UVB irradiation. In addition, preserving proteasome function resulted in lowering the extent of the irradiation-induced protein oxidative damage, opening up new strategies for protection of epidermal cells against the detrimental effects of UV irradiation.

Photocontrol of nitric oxide production in cell culture using a caged isoform selective inhibitor

Over the past decade, multiphoton microscopy has progressed from a photonic novelty to a technique whose application is currently experiencing exponential growth in the biological sciences. A novel application of this technology with significant therapeutic potential is the control of drug activity by multiphoton photolysis of caged therapeutics. As an initial case study, the potent isoform selective inhibitor N-(3-(aminomethyl)benzyl) acetamidine (1400W) of inducible nitric oxide synthase (iNOS) has been conjugated to a caging molecule 6-bromo-7-hydroxy-4-hydroxyquinoline-2-ylmethyl acetyl ester (Bhc). Here we present the first report of a bulk therapeutic effect, inhibition of nitric oxide production, in mammalian cell culture by multiphoton photolysis of a caged drug, Bhc-1400W. Mouse macrophage RAW 264.7 cells induced with bacterial lipopolysaccharides to express iNOS were used to assess the therapeutic value of the conjugated inhibitor. Both 1400W and Bhc-1400W are stable in metabolically active cells and an optimal time interval for the photorelease of the inhibitor was determined. The ratios of the IC(50) values of Bhc-1400W over 1400W calculated in the presence of iNOS enzyme and in RAW 264.7 cell culture are 19 and 100, respectively, indicating that a broad therapeutic range exists in cell culture. Multiphoton uncaging protocols and therapeutic doses of inhibitors were not cytotoxic. Photocontrol of LPS induced nitric oxide production was achieved in mammalian cell culture using a single laser focal volume. This technology has the potential to control active drug concentrations in vivo, a lack of which is one of the main problems currently associated with systemic drug administration.

Optical manipulation in combination with multiphoton microscopy for single-cell studies

We demonstrate how optical tweezers can be incorporated into a multiphoton microscope to achieve three-dimensional imaging of trapped cells. The optical tweezers, formed by a cw 1064 nm Nd:YVO4 laser, were used to trap live yeast cells in suspension while the 4',6-diamidino-2-phenylindole-stained nucleus was imaged in three dimensions by use of a pulsed femtosecond laser. The trapped cell was moved in the axial direction by changing the position of an external lens, which was used to control the divergence of the trapping laser beam. This gives us a simple method to use optical tweezers in the laser scanning of confocal and multiphoton microscopes. It is further shown that the same femtosecond laser as used for the multiphoton imaging could also be used as laser scissors, allowing us to drill holes in the membrane of trapped spermatozoa.

NADH enzyme-dependent fluorescence recovery after photobleaching (ED-FRAP): applications to enzyme and mitochondrial reaction kinetics, in vitro

NADH enzyme-dependent fluorescence recovery after photobleaching (ED-FRAP) was evaluated for studying enzyme kinetics in vitro and in isolated mitochondria. Mass, optical, and nuclear magnetic resonance spectroscopy data were consistent with the UV NADH photolysis reaction being NADH --> NAD* + H+ + e-. The overall net reaction was O2 + 2NADH + 2H+ --> 2NAD+ + 2H2O, or in the presence of other competing electron acceptors such as cytochrome c, NADH + 2Cyt(ox) --> NAD+ + H+ + 2Cyt(red). Solution pH could differentiate between these free-radical scavenging pathways. These net reactions represent the photooxidation of NADH to NAD+. Kinetic models and acquisition schemes were developed, varying [NADH] and [NAD] by altering NADH photolysis levels, for extracting kinetic parameters. UV irradiation levels used did not damage mitochondrial function or enzymatic activity. In mitochondria, [NADH] is a high affinity product inhibitor that significantly reduced the NADH regeneration rate. Matrix NADH regeneration only slightly exceeded the net rate of NADH consumption, suggesting that the NADH regeneration process is far from equilibrium. Evaluation of NADH regeneration in active mitochondria, in comparison to rotenone-treated preparations, revealed other regulatory elements in addition to matrix [NADH] and [NAD] that have yet to be fully characterized. These studies demonstrate that the rapid UV photolysis of NADH to NAD is an effective tool in evaluating the steady-state kinetic properties of enzyme systems. Initial data support the notion that the NADH regeneration process is far from equilibrium in mitochondria and is potentially controlled by NADH levels as well as several other matrix factors.

Modern laser scanning microscopy in biology, biotechnology and medicine

Laser microscopic techniques currently used in morphology and cell biology represent highly sensitive tools for detecting biomolecules within their natural environment. Use of the fluorescence-, reflectance- and transmission modes of confocal laser scanning microscopes (CLSM) equipped with He-Ne- and Ar+-ion lasers for CeIV and DAB based detection of endogenous or immunobound enzymatic activities in tissue sections (vibratome, cryostat, paraffin and semithin plastic sections) opens a wide range of interesting new possibilities in cellular and molecular biology. Increased resolution power, blur-free confocal imaging, higher sensitivity, optical sectioning capability and 3D-image analysis provide a large quantity of valuable information about biological objects specimens. The new infrared multiphoton laser scanning microscopy (NIR-LSM) is increasingly becoming the optical tool of choice for (a) fluorescence imaging of cellular and subcellular components with high spatial and temporal resolution, (b) fluorescence resonance energy transfer between physiologically relevant molecular species involving protein-protein interactions, (c) nanoprocessing within living cells and tissues, with varied applications in (d) photochemistry and (e) medical diagnostics as well. Both, CLSM and NIR-LSM as modern microscopical strategies are indispensable in basic research and will prove to be invaluable for clinical diagnostic studies and therapy in the near future.

Impairment of proteasome function upon UVA- and UVB-irradiation of human keratinocytes

The major environmental influence for epidermal cells is sun exposure and the harmful effect of UV radiation on skin is related to the generation of reactive oxygen species that are altering cellular components including proteins. It is now well established that the proteasome is responsible for the degradation of oxidized proteins. Therefore, the effects of UV-irradiation on proteasome have been investigated in human keratinocyte cultures. Human keratinocytes were irradiated with 10 J/cm(2) of UVA and 0.05 J/cm(2) of UVB and proteasome peptidase activities were measured in cell lysates using fluorogenic peptides. All three peptidase activities were decreased as early as 1 h and up to 24 h after irradiation of the cells. Increased levels of oxidized and ubiquitinated proteins as well as proteins modified by the lipid peroxidation product 4-hydroxy-2-nonenal were also observed in irradiated cells. However, immunopurified 20S proteasome exhibited no difference in both peptidase specific activities and 2D gel pattern of subunits in irradiated cells, ruling out the possibility that the 20S proteasome could be a target for the UV-induced damage. Finally, extracts from irradiated keratinocytes were able to inhibit degradation by the proteasome, demonstrating the presence of endogeneous inhibitors, including 4-hydroxy-2-nonenal modified proteins, generated upon UV-irradiation.

Mycosporine-like amino acids and related Gadusols: biosynthesis, acumulation, and UV-protective functions in aquatic organisms

Organisms living in clear, shallow water are exposed to the damaging wavelengths of solar ultraviolet radiation (UVR) coincident with the longer wavelengths of photosynthetically available radiation (PAR) also necessary for vision. With the general exception of bacteria, taxonomically diverse marine and freshwater organisms have evolved the capacity to synthesize or accumulate UV-absorbing mycosporine-like amino acids (MAAs), presumably for protection against environmental UVR. This review highlights the evidence for this UV-protective role while also considering other attributed functions, including reproductive and osmotic regulation and vision. Probing the regulation and biosynthesis of MAAs provides insight to the physiological evolution and utility of UV protection and of biochemically associated antioxidant defenses.

Ultraviolet A1 radiation induces nitric oxide synthase-2 expression in human skin endothelial cells in the absence of proinflammatory cytokines

Skin exposure to ultraviolet radiation from sunlight causes erythema and edema formation as well as inflammatory responses. As some of these ultraviolet-induced effects are potentially mediated by nitric oxide synthases, we examined the role of cytokines and ultraviolet A1 radiation (340-400 nm) on the expression of the nitric oxide synthase-2 in endothelia of normal human skin biopsies during short-term organ culture as well as expression and activity of the nitric oxide synthase-2 in in vitro cell cultures of human dermal endothelial cells. Both, cytokine challenge (interleukin-1beta + tumor necrosis factor-alpha + interferon-gamma) but also ultraviolet A1 exposure (50 J per cm2) in the absence of cytokines led to the expression of nitric oxide synthase-2 in human skin organ cultures as shown by immunohistochemistry. Moreover, exposing human dermal endothelial cell cultures to proinflammatory cytokines but also to ultraviolet A1 radiation (6-24 J per cm2) in the absence of cytokines resulted in significant nitric oxide synthase-2 mRNA and protein expression as well as enzyme activity. Ultraviolet A1 irradiation of cytokine activated cells led to further increases in nitric oxide synthase-2 mRNA, protein expression, and enzyme activity. Moreover, a reporter gene assay using a human nitric oxide synthase-2 promoter construct provide evidence that ultraviolet A1, in the absence of cytokines, induces nitric oxide synthase-2 expression and activity, as previously shown for cytokines. Thus, the results presented here demonstrate for the first time that in dermal endothelia of human skin ultraviolet A1 radiation alone represents a proinflammatory stimulus sufficient to initiate nitric oxide synthase-2 expression as well as activity comparable with the respective response seen in the presence of proinflammatory cytokines.