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Hypoxia is one of the hallmarks of solid tumor, which heavily restricts the clinical cancer therapy treatments, especially for the oxygen (O 2 ) -dependent photodynamic therapy (PDT). Herein, an intelligent multi-layer nanostructure was developed for decreasing the O 2 -consumption and elevating the O 2 -supply simultaneously. The cell respiration inhibitor -atovaquone (ATO) molecules were reserved in the middle mesoporous silicon layer, and thus were intelligently released at the tumor site after the degradation of gatekeeper of MnO 2 layer, which effectively inhibit tumor respiration metabolism to elevate oxygen content. Meanwhile, the degradation of MnO 2 layer can generate O 2 , further boosting oxygen content. Moreover, the inner upconversion nanostructures as the near infrared (NIR) light-transducers enable to activate photosensitizers for deep-tissue PDT. Systematic experiments demonstrate that this suppressing O 2 -consumption and O 2 -generation strategy improved oxygen supply to boost the singlet oxygen generation to eradicate cancer cells under NIR light excitation. Better still, superior trimodality imaging capabilities (computed tomography (CT), NIR-II window fluorescence, and tumor microenvironment-responsive T1-weighted magnetic resonance (MR) imaging) of the nanoplatform were evaluated. Our findings offer a promising aproach to conquer the serious hypoxia problem in cancer therapy by turning down the O 2 metabolism aveneue and simultaneously generating O 2 ., (Copyright © 2020 Elsevier Ltd. All rights reserved.)

Photobiomodulation (PBM) involves light to activate cellular signaling pathways leading to cell proliferation or death. In this work, fluorescence and Coherent anti-Stokes Raman Scattering (CARS) imaging techniques were applied to assess apoptosis in human cervical cancer cells (HeLa) induced by near infrared (NIR) laser light (808 nm). Using the Caspase 3/7 fluorescent probe to identify apoptotic cells, we found that the pro-apoptotic effect is significantly dependent of irradiation dose. The highest apoptosis rate was noted for the lower irradiation doses, that is, 0.3 J/cm 2 (~58%) and 3 J/cm 2 (~28%). The impact of light doses on proteins/lipids intracellular metabolism and distribution was evaluated using CARS imaging, which revealed apoptosis-associated reorganization of nuclear proteins and cytoplasmic lipids after irradiation with 0.3 J/cm 2 . Doses of NIR light causing apoptosis (0.3, 3 and 30 J/cm 2 ) induced a gradual increase in the nuclear protein level over time, in contrast to proteins in cells non-irradiated and irradiated with 10 J/cm 2 . Furthermore, irradiation of the cells with the 0.3 J/cm 2 dose resulted in lipid droplets (LDs) accumulation, which was apparently caused by an increase in reactive oxygen species (ROS) generation. We suggest that PBM induced apoptosis could be caused by the ability of NIR light to trigger excessive LDs formation which, in turn, induces cellular cytotoxicity., (© 2019 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)

A nanosized drug complex was explored to improve the efficiency of cancer chemotherapy, complementing it with nanodelivery and photodynamic therapy. For this, nanomolar amounts of a non-covalent nanocomplex of Doxorubicin (Dox) with carbon nanoparticle C 60 fullerene (C 60 ) were applied in 1:1 and 2:1 molar ratio, exploiting C 60 both as a drug-carrier and as a photosensitizer. The fluorescence microscopy analysis of human leukemic CCRF-CEM cells, in vitro cancer model, treated with nanocomplexes showed Dox's nuclear and C 60 's extranuclear localization. It gave an opportunity to realize a double hit strategy against cancer cells based on Dox's antiproliferative activity and C 60 's photoinduced pro-oxidant activity. When cells were treated with 2:1 C 60 -Dox and irradiated at 405 nm the high cytotoxicity of photo-irradiated C 60 -Dox enabled a nanomolar concentration of Dox and C 60 to efficiently kill cancer cells in vitro. The high pro-oxidant and pro-apoptotic efficiency decreased IC 50 16, 9 and 7 × 10 3 -fold, if compared with the action of Dox, non-irradiated nanocomplex, and C 60 's photodynamic effect, correspondingly. Hereafter, a strong synergy of therapy arising from the combination of C 60 -mediated Dox delivery and C 60 photoexcitation was revealed. Our data indicate that a combination of chemo- and photodynamic therapies with C 60 -Dox nanoformulation provides a promising synergetic approach for cancer treatment.

Red and near-infrared (NIR) light effect on Ca 2+ ions flux through the influence on N-methyl-D-aspartate receptors (NMDARs) and their functioning in HeLa cells was studied in vitro. Cells were irradiated by 650 and 808 nm laser light at different power densities and doses and the obtained effect was compared with that caused by the pharmacological agents. The laser light was found to elevate Ca 2+ influx into cell cytoplasm in a dose-dependent manner without changes of the NMDAR functioning. Furthermore, the light of both wavelengths demonstrated the ability to elevate Ca 2+ influx under the pharmacological blockade of NMDARs and also might partially abolish the blockade enhancing Ca 2+ influx after selective stimulation of the receptors with NMDA. Simultaneously, the light at moderate doses demonstrated a photobiostimulating effect on cells. Based on our experiments and data reported in the literature, we suggest that the low-power visible and NIR light can instigate a cell membrane depolarization via nonthermal activation, resulting in the fast induction of Ca 2+ influx into cells. The obtained results also demonstrate that NIR light can be used for nonthermal and nonpharmacological stimulation of NMDARs in cancer cells., (© 2019 Wiley Periodicals, Inc.)

Fluorescence (FL) and X-ray computed tomography (CT) imaging-guided photodynamic therapy (PDT) can provide a powerful theranostic tool to visualize, monitor, and treat cancer and other diseases with enhanced accuracy and efficacy. Methods: In this study, clinically approved iodinated CT imaging contrast agent (CTIA) iodixanol and commercially available photosensitizer (PS) meso-tetrakis (4-sulphonatophenyl) porphine (TPPS 4 ) were co-encapsulated in biocompatible PEGylated nanoliposomes (NL) for enhanced anticancer PDT guided by bimodal (FL and CT) imaging. Results: The NL co-encapsulation of iodixanol and TPPS 4 (LIT) lead to an increase in singlet oxygen generation by PS via the intraparticle heavy-atom (iodine) effect on PS molecules, as it was confirmed by both direct and indirect measurements of singlet oxygen production. The confocal imaging and PDT of cancer cells were performed in vitro , exhibiting the cellular uptake of TPPS 4 formulations and enhanced PDT efficacy of LIT. Meanwhile, bimodal (FL and CT) imaging was also conducted with tumor-bearing mice and the imaging results manifested high-efficient accumulation and retention of LIT in tumors. Moreover, PDT of tumor in vivo was shown to be drastically more efficient with LIT than with other formulations of TPPS 4 . Conclusion: This study demonstrated that LIT can serve as a highly efficient theranostic nanoplatform for enhanced anticancer PDT guided by bimodal (FL and CT) imaging., Competing Interests: Competing Interests: The authors have declared that no competing interest exists.

Nuclear organelles are viscous droplets, created by concentration-dependent condensation and liquid-liquid phase separation of soluble proteins. Nuclear organelles have been actively investigated for their role in cellular regulation and disease. However, these studies are highly challenging to perform in live cells, and therefore, their physico-chemical properties are still poorly understood. In this study, we describe a fluorescence lifetime imaging approach for real-time monitoring of protein condensation in nuclear organelles of live cultured cells. This approach unravels surprisingly large cyclic changes in concentration of proteins in major nuclear organelles including nucleoli, nuclear speckles, Cajal bodies, as well as in the clusters of heterochromatin. Remarkably, protein concentration changes are synchronous for different organelles of the same cells. We propose a molecular mechanism responsible for synchronous accumulations of proteins in the nuclear organelles. This mechanism can serve for general regulation of cellular metabolism and contribute to coordination of gene expression.

Optical properties of the rat head tissues (brain cortex, cranial bone and scalp skin) are assessed, aiming at transcranial light applications such as optical imaging and phototherapy. The spectral measurements are carried out over the wide spectral range of 350 to 2800 nm, involving visible, near-infrared (NIR) and short-wave infrared (SWIR) regions. Four tissue transparency windows are considered: ~700 to 1000 nm (NIR-I), ~1000 to 1350 nm (NIR-II), ~1550 to 1870 nm (NIR-III or SWIR) and ~2100 to 2300 nm (SWIR-II). The values of attenuation coefficient and total attenuation length are determined for all windows and tissue types. The spectra indicate transmittance peaks in NIR, NIR-II and SWIR-II, with maximum tissue permeability for SWIR light. The use of SWIR-II window for the transcranial light applications is substantiated. Furthermore, absorbance of the head tissues is investigated in details, by defining and describing the characteristic absorption peaks in NIR-SWIR., (© 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)

The enteric nervous system (ENS) and a glutamate receptor (GluR), N-methyl-D-aspartate receptor (NMDAR), participate in gastric acid secretion (GAS) regulation. NMDARs are localized in different stomach cells; however, knowledge of NMDAR expression and function in the ENS is limited. In the present study, we clarified the types of stomach cells that express the NMDARs that are involved in GAS regulation. The pharmacological method of isolated stomach perfusion by Ghosh and Shild combined with direct mapping of NMDARs by fluorescence microscopy in the rat stomach was employed. By immunofluorescence labeling with an anti-NMDA-NR1 antibody, NMDARs were found to be highly expressed in nerve cells of the submucosal and myenteric plexuses in the stomach. The exact localization of the NMDARs relevant to GAS and its mechanism of action were determined by stimulating different receptors of neuronal and stomach cells using specific secretagogues for NMDA and by selectively blocking those receptors. NMDARs relevant to GAS stimulation are mainly localized in cholinergic interneurons; however, all of the nerve cells of the submucosal ganglia are involved in the stimulating process. In addition, the NMDARs in parietal cells are involved in gastric acid inhibition via influencing H 2 -histamine receptors.

Core-shell nanostructures associated with photonics techniques have found innumerous applications in diagnostics and therapy. In this work, we introduce a novel core-shell nanostructure design that serves as a multimodal optical imaging contrast agent for dental adhesion evaluation. This nanostructure consists of a rare-earth-doped (NaYF 4 :Yb 60%, Tm 0.5%)/NaYF 4 particle as the core (hexagonal prism, ~51 nm base side length) and the highly refractive TiO 2 material as the shell (~thickness of 15 nm). We show that the TiO 2 shell provides enhanced contrast for optical coherence tomography (OCT), while the rare-earth-doped core upconverts excitation light from 975 nm to an emission peaked at 800 nm for photoluminescence imaging. The OCT and the photoluminescence wide-field images of human tooth were demonstrated with this nanoparticle core-shell contrast agent. In addition, the described core-shell nanoparticles (CSNps) were dispersed in the primer of a commercially available dental bonding system, allowing clear identification of dental adhesive layers with OCT. We evaluated that the presence of the CSNp in the adhesive induced an enhancement of 67% scattering coefficient to significantly increase the OCT contrast. Moreover, our results highlight that the upconversion photoluminescence in the near-infrared spectrum region is suitable for image of deep dental tissue., (© 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)

Optical and photoelectric properties of metamorphic InAs/InGaAs and conventional pseudomorphic InAs/GaAs quantum dot (QD) structures were studied. We used two different electrical contact configurations that allowed us to have the current flow (i) only through QDs and embedding layers and (ii) through all the structure, including the GaAs substrate (wafer). Different optical transitions between states of QDs, wetting layers, GaAs or InGaAs buffers, and defect-related centers were studied by means of photovoltage (PV), photoconductivity (PC), photoluminescence (PL), and absorption spectroscopies. It was shown that the use of the InGaAs buffer spectrally shifted the maximum of the QD PL band to 1.3 μm (telecommunication range) without a decrease in the yield. Photosensitivity for the metamorphic QDs was found to be higher than that in GaAs buffer while the photoresponses for both metamorphic and pseudomorphic buffer layers were similar. The mechanisms of PV and PC were discussed for both structures. The dissimilarities in properties of the studied structures are explained in terms of the different design. A critical influence of the defects on the photoelectrical properties of both structures was observed in the spectral range from 0.68 to 1.0 eV for contact configuration (ii), i.e., in the case of electrically active GaAs wafer. No effect of such defects on the photoelectric spectra was found for configuration (i), when the structures were contacted to the top and bottom buffers; only a 0.83 eV feature was observed in the photocurrent spectrum of pseudomorphic structure and interpreted to be related to defects close to InAs/GaAs QDs.

The bipolar effect of GaAs substrate and nearby layers on photovoltage of vertical metamorphic InAs/InGaAs in comparison with pseudomorphic (conventional) InAs/GaAs quantum dot (QD) structures were studied. Both metamorphic and pseudomorphic structures were grown by molecular beam epitaxy, using bottom contacts at either the grown n + -buffers or the GaAs substrate. The features related to QDs, wetting layers, and buffers have been identified in the photoelectric spectra of both the buffer-contacted structures, whereas the spectra of substrate-contacted samples showed the additional onset attributed to EL2 defect centers. The substrate-contacted samples demonstrated bipolar photovoltage; this was suggested to take place as a result of the competition between components related to QDs and their cladding layers with the substrate-related defects and deepest grown layer. No direct substrate effects were found in the spectra of the buffer-contacted structures. However, a notable negative influence of the n + -GaAs buffer layer on the photovoltage and photoconductivity signal was observed in the InAs/InGaAs structure. Analyzing the obtained results and the performed calculations, we have been able to provide insights on the design of metamorphic QD structures, which can be useful for the development of novel efficient photonic devices.

The tetrapyrrole structure of porphyrins used as photosentizing agents is thought to determine uptake and retention by malignant epithelial cancer cells. To assess the contribution of the oxidized state of individual rings to these cellular processes, bacteriochlorophyll a was converted into the ring "D" reduced 3-devinyl-3-[1-(1-hexyloxy)ethyl]pyropheophorbide-a (HPPH) and the corresponding ring "B" reduced isomer (iso-HPPH). The carboxylic acid analogs of both ring "B" and ring "D" reduced isomers showed several-fold higher accumulation into the mitochondria and endoplasmic reticulum by primary culture of human lung and head and neck cancer cells than the corresponding methyl ester analogs that localize primarily to granular vesicles and to a lesser extent to mitochondria. However, long-term cellular retention of these compounds exhibited an inverse relationship with tumor cells generally retaining better the methyl-ester derivatives. In vivo distribution and tumor uptake was evaluated in the isogenic model of BALB/c mice bearing Colon26 tumors using the respective 14 C-labeled analogs. Both carboxylic acid derivatives demonstrated similar intracellular localization and long-term tumor cure with no significant skin phototoxicity. PDT-mediated tumor action involved vascular damage, which was confirmed by a reduction in blood flow and immunohistochemical assessment of damage to the vascular endothelium. The HPPH stereoisomers (epimers) showed identical uptake (in vitro & in vivo), intracellular retention and photoreaction.

To investigate the impact of linker(s) joining the photosensitizer HPPH [3-(1'-hexyloxy) ethyl-3-devinylpyropheophorbide-a] and the cyanine dye (CD) in tumor-imaging and photodynamic therapy (dual-function agents), a series of HPPH-CD conjugates were synthesized. The modifications were done in an attempt to minimize Forster Resonance Energy Transfer (FRET) between the two chromophores and maximize singlet oxygen production. Among the conjugates containing variable length of linkers, the HPPH-CD conjugate, in which the photosensitizer (PS) and the CD was joined by four Carbon [(CH2)4] units showed higher tumor uptake, improved tumor contrast and limited skin uptake in mice bearing Colon-26 (BALB/c) or U87 tumors in Nude mice. The bi-functional agents in which the HPPH was linked at the meta-position of phenyl-substituted CD 5, 6 and 7 showed longer tumor response (cure) than the corresponding para-substituted analogs 2, 3, and 4, which suggests that the orientation of the PS and CD moieties within the conjugate also makes a substantial difference in tumor-specificity. Compared to HPPH, the singlet oxygen yields of all the HPPH-CD conjugates were significantly low, and required a higher therapeutic dose to achieve the same in vivo response obtained by HPPH-PDT alone. However, conjugate 6 produced a higher singlet oxygen yield with reduced FRET and exhibited enhanced long-term PDT efficacy in mice bearing Colon-26 (BALB/c) and U87 tumors (nude) than its counterparts, including our lead compound (HPPH-CD), making it the most efficacious of the series. Thus, these conjugates bearing cyanine dye moiety (CD) provide an opportunity of imaging deeply seated tumors for fluorescence-guided surgery with an option of PDT., (Copyright © 2016 Elsevier Masson SAS. All rights reserved.)

This paper introduces the concept of in-situ upconversion of deep penetrating near infrared light via second harmonic generation from ZnO nanocrystals delivered into cells to effect photo activated therapies, such as photodynamic therapy, which usually require activation by visible light with limited penetration through biological tissues. We demonstrated this concept by subcellular activation of a photodynamic therapy drug, Chlorin e6, excited within its strong absorption Soret band by the second harmonic (SH) light, generated at 409 nm by ZnO nanocrystals, which were targeted to cancer cells and internalized through the folate-receptor mediated endocytosis. By a combination of theoretical modeling and experimental measurements, we show that SH light, generated in-situ by ZnO nanocrystals significantly contributes to activation of photosensitizer, leading to cell death through both apoptotic and necrotic pathways initiated in the cytoplasm. This targeted photodynamic action was studied using label-free Coherent Anti-Stokes Raman Scattering imaging of the treated cells to monitor changes in the distribution of native cellular proteins and lipids. We found that initiation of photodynamic therapy with upconverted light led to global reduction in the intracellular concentration of macromolecules, likely due to suppression of proteins and lipids synthesis, which could be considered as a real-time indicator of cellular damage from photodynamic treatment. In prospective applications this in-situ photon upconversion could be further extended using ZnO nanocrystals surface functionalized with a specific organelle targeting group, provided a powerful approach to identify and consequently maximize a cellular response to phototherapy, selectively initiated in a specific cellular organelle., (Copyright © 2016 Elsevier Ltd. All rights reserved.)

We examined two selenorhodamines with amide and thioamide functionality at the 5-position of a 9-(2-thienyl) substituent on the selenoxanthylium analogue of the Texas-red core for their potential as photosensitizers for photodynamic therapy (PDT) in P-glycoprotein (P-gp)-expressing Colo-26 cells. These compounds were examined for their photophysical properties (absorption, fluorescence, and ability to generate singlet oxygen), for their uptake into Colo-26 cells in the absence or presence of verapamil, for their dark and phototoxicity toward Colo-26 cells, and for their co-localization with mitochondrial-specific agents in Colo-26 cells. Both compounds were extremely effective photosensitizers with values of EC50 ⩽ 4 × 10(-8)M toward Colo-26 cells with 1.0 J cm(-2) laser light delivered at 630 ± 2 nm., (Copyright © 2015 Elsevier Ltd. All rights reserved.)

Development of long-term implantable luminescent biosensors for subcutaneous oxygen has proved challenging due to difficulties in immobilizing a biocompatible matrix that prevents sensor aggregation yet maintains sufficient concentration for transdermal optical detection. Here, Pd-porphyrins can be used as PEG cross-linkers to generate a polyamide hydrogel with extreme porphyrin density (≈5 × 10(-3) m). Dye aggregation is avoided due to the spatially constraining 3D mesh formed by the porphyrins themselves. The hydrogel exhibits oxygen-responsive phosphorescence and can be stably implanted subcutaneously in mice for weeks without degradation, bleaching, or host rejection. To further facilitate oxygen detection using steady-state techniques, an oxygen-non-responsive companion hydrogel is developed by blending copper and free base porphyrins to yield intensity-matched luminescence for ratiometric detection., (© 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)

We present a magnetoplasmonic nanoplatform combining gold nanorods (GNR) and iron-oxide nanoparticles within phospholipid-based polymeric nanomicelles (PGRFe). The gold nanorods exhibit plasmon resonance absorbance at near infrared wavelengths to enable photoacoustic imaging and photothermal therapy, while the Fe3O4 nanoparticles enable magnetophoretic control of the nanoformulation. The fabricated nanoformulation can be directed and concentrated by an external magnetic field, which provides enhancement of a photoacoustic signal. Application of an external field also leads to enhanced uptake of the magnetoplasmonic formulation by cancer cells in vitro. Under laser irradiation at the wavelength of the GNR absorption peak, the PGRFe formulation efficiently generates plasmonic nanobubbles within cancer cells, as visualized by confocal microscopy, causing cell destruction. The combined magnetic and plasmonic functionalities of the nanoplatform enable magnetic field-directed, imaging-guided, enhanced photo-induced cancer therapy., From the Clinical Editor: In this study, a nano-formulation of gold nanorods and iron oxide nanoparticles is presented using a phospholipid micelle-based delivery system for magnetic field-directed and imaging-guided photo-induced cancer therapy. The gold nanorods enable photoacoustic imaging and photothermal therapy, while the Fe3O4 nanoparticles enable magnetophoretic control of the formulation. This and similar systems could enable more precise and efficient cancer therapy, hopefully in the near future, after additional testing., (Copyright © 2013 Elsevier Inc. All rights reserved.)

A family of upconverting nanoparticles (UCNPs) with a tunable UV enhancement is developed via a facile approach. The design leads to a maximum 9-fold enhancement in comparison with known optimal β-phase core/shell UCNPs in water. A highly effective and rapid in situ real-time live-cell photoactivation is recorded for the first time with such nanoparticles., (Copyright © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)

We report herein a simple and efficient approach to the synthesis of a variety of meso-substituted purpurinimides. The reaction of meso-substituted purpurinimide with N-bromosuccinimide regioselectively introduced a bromo functionality at the 20-position, which on further reaction with a variety of boronic acids under Suzuki reaction conditions yielded the corresponding meso-substituted analogues. Interestingly, the free base and the metalated analogues showed remarkable differences in photosensitizing efficacy (PDT) and tumor-imaging ability. For example, the free-base conjugate showed significant in vitro PDT efficacy, but limited tumor avidity in mice bearing tumors, whereas the corresponding Ni(II) derivative did not produce any cell kill, but showed excellent tumor-imaging ability at a dose of 0.3 μmol kg(-1) at 24, 48, and 72 h post-injection. The limited PDT efficacy of the Ni(II) analogue could be due to its inability to produce singlet oxygen, a key cytotoxic agent required for cell kill in PDT. Based on electrochemical and spectroelectrochemical data in DMSO, the first one-electron oxidation (0.52 V vs. SCE) and the first one-electron reduction (-0.57-0.67 V vs. SCE) of both the free base and the corresponding Ni(II) conjugates are centered on the cyanine dye, whereas the second one-electron reduction (-0.81 V vs. SCE) of the two conjugates is assigned to the purpurinimide part of the molecule. Reduction of the cyanine dye unit is facile and occurs prior to reduction of the purpurinimide group, which suggests that the cyanine dye unit as an oxidant could be the driving force for quenching of the excited triplet state of the molecules. An interaction between the cyanine dye and the purpurinimide group is clearly observed in the free-base conjugate, which compares with a negligible interaction between the two functional groups in the Ni(II) conjugate. As a result, the larger HOMO-LUMO gap of the free-base conjugate and the corresponding smaller quenching constant is a reason to decrease the intramolecular quenching process and increase the production of singlet oxygen to some degree., (Copyright © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)

We describe the development of novel and biocompatible core/shell (α-NaYbF(4):Tm(3+))/CaF(2) nanoparticles that exhibit highly efficient NIR(in)-NIR(out) upconversion (UC) for high contrast and deep bioimaging. When excited at ~980 nm, these nanoparticles emit photoluminescence (PL) peaked at ~800 nm. The quantum yield of this UC PL under low power density excitation (~0.3 W/cm(2)) is 0.6 ± 0.1%. This high UC PL efficiency is realized by suppressing surface quenching effects via heteroepitaxial growth of a biocompatible CaF(2) shell, which results in a 35-fold increase in the intensity of UC PL from the core. Small-animal whole-body UC PL imaging with exceptional contrast (signal-to-background ratio of 310) is shown using BALB/c mice intravenously injected with aqueously dispersed nanoparticles (700 pmol/kg). High-contrast UC PL imaging of deep tissues is also demonstrated, using a nanoparticle-loaded synthetic fibrous mesh wrapped around rat femoral bone and a cuvette with nanoparticle aqueous dispersion covered with a 3.2 cm thick animal tissue (pork).

We report a novel post-loading approach for constructing a multifunctional biodegradable polyacrylamide (PAA) nanoplatform for tumor-imaging (fluorescence) and photodynamic therapy (PDT). This approach provides an opportunity to post-load the imaging and therapeutic agents at desired concentrations. Among the PAA nanoparticles, a formulation containing the photosensitizer, HPPH [3-(1'-hexyloxyethyl)pyropheophorbide-a], and the cyanine dye in a ratio of 2:1 minimized the undesirable quenching of the HPPH electronic excitation energy because of energy migration within the nanoparticles and/or Förster (fluorescence) resonance energy transfer (FRET) between HPPH and cyanine dye. An excellent tumor-imaging (NIR fluorescence) and phototherapeutic efficacy of the nanoconstruct formulation is demonstrated. Under similar treatment parameters the HPPH in 1% Tween 80/5% aqueous dextrose formulation was less effective than the nanoconstruct containing HPPH and cyanine dye in a ratio of 2 to 1. This is the first example showing the use of the post-loading approach in developing a nanoconstructs for tumor-imaging and therapy., (Copyright © 2012 Elsevier Inc. All rights reserved.)

In this work we demonstrate the potential use of gold nanoparticles as contrast agents for the optical coherence tomography (OCT) imaging technique in dentistry. Here, a new in situ photothermal reduction procedure was developed, producing spherical gold nanoparticles inside dentinal layers and tubules. Gold ions were dispersed in the primer of commercially available dental bonding systems. After the application and permeation in dentin by the modified adhesive systems, the dental bonding materials were photopolymerized concurrently with the formation of gold nanoparticles. The gold nanoparticles were visualized by scanning electron microscopy (SEM). The SEM images show the presence of gold nanospheres in the hybrid layer and dentinal tubules. The diameter of the gold nanoparticles was determined to be in the range of 40 to 120 nm. Optical coherence tomography images were obtained in two- and three-dimensions. The distribution of nanoparticles was analyzed and the extended depth of nanosphere production was determined. The results show that the OCT technique, using in situ formed gold nanoparticles as contrast enhancers, can be used to visualize dentin structures in a non-invasive and non-destructive way.

We report core/shell NaYbF(4):Tm(3+)/NaGdF(4) nanocrystals to be used as probes for bimodal near infrared to near infrared (NIR-to-NIR) upconversion photoluminescence (UCPL) and magnetic resonance (MR) imaging. The NaYbF(4):Tm(3+) nanocrystals were previously reported to produce the intense NIR-to-NIR UCPL peaked at ∼800 nm under excitation at ∼975 nm. We have found that the growth of a NaGdF(4) shell on surface of the NaYbF(4):Tm(3+) nanocrystals results in the increase in the intensity of UCPL of Tm(3+) ions by about 3 times. Unlike biexponential PL decay of NaYbF(4):Tm(3+) nanocrystals, the PL decay of NaYbF(4):Tm(3+)/NaGdF(4) core/shell nanocrystals is single exponential and of longer lifetime due to the suppression of surface quenching effects for Tm(3+) PL. The growth of a NaGdF(4) shell on surface of the NaYbF(4):Tm(3+) nanocrystals also provides high MR relaxivity from paramagnetic Gd(3+) ions contained in the shell. The T1-weighted MR signal of the (NaYbF(4):2% Tm(3+))/NaGdF(4) nanoparticles was measured to be about 2.6 mM(-1)s(-1). Due to the combined presence of efficient optical and MR imaging capabilities, nanoprobes based on NaYbF(4):Tm(3+)/NaGdF(4) fluoride nanophosphors can be considered as a promising platform for simultaneous bimodal PL and MR bioimaging., (© The Royal Society of Chemistry 2011)

Spectral-fluorescent properties of benzothiazole styryl monomer (Bos-3) and homodimer (DBos-21) dyes in presence of DNA were studied. The dyes enhance their fluorescence intensity in 2-3 orders of magnitude upon interaction with DNA. Studied styrylcyanines in DNA presence demonstrate rather high values of two-photon absorption (TPA) cross-section, which are comparable with the values of TPA cross section of the rhodamine dyes. An applicability of the styrylcyanines as probes for the fluorescence microscopy of living cells was studied. It was shown that both dyes are cell-permeable but homodimer dye DBos-21 produces noticeably brighter staining of HeLa cells comparing with monomer dye Bos-3. Molecules of DBos-21 initially bind to the nucleic acids-containing cell organelles (presumable mitochondria) and are able to penetrate into the cell nucleus. Thus, homodimer styryl DBos-21 dye is viewed as efficient stain for single-photon and two-photon excitation fluorescence imaging of living cells.

We report a novel nanoformulation of a photosensitizer (PS), for photodynamic therapy (PDT) of cancer, where the PS molecules are covalently incorporated into organically modified silica (ORMOSIL) nanoparticles. We found that the covalently incorporated PS molecules retained their spectroscopic and functional properties and could robustly generate cytotoxic singlet oxygen molecules upon photoirradiation. The synthesized nanoparticles are of ultralow size ( approximately 20 nm) and are highly monodispersed and stable in aqueous suspension. The advantage offered by this covalently linked nanofabrication is that the drug is not released during systemic circulation, which is often a problem with physical encapsulation. These nanoparticles are also avidly uptaken by tumor cells in vitro and demonstrate phototoxic action, thereby highlighting their potential in diagnosis and PDT of cancer.

2,4-Bis(4-dimethylaminophenyl)-6-alkylthiopyrylium and selenopyrylium dyes are essentially nonfluorescent (phi F < 0.001) and are poor generators of singlet oxygen in aqueous solution. However, upon complexation to calf thymus DNA, quantum yields for both fluorescence and generation of singlet oxygen increased dramatically. Irradiation of the dye-DNA complexes produced strand breaks in the DNA. The photodamage is not observed in the absence of oxygen and is suppressed by the addition of the singlet oxygen quencher imidazole. The inactivation of the pseudo-rabies virus upon treatment of oxygenated leukodepleted 20% hematocrit red blood cell suspensions with the chalcogenopyrylium dyes and light followed the same trend observed with quantum yields for the generation of singlet oxygen in the dye-DNA complexes.

A series of thio- and selenopyrylium analogues of 2,4-di(4-dimethylaminophen-yl)-6-methylthiopyrylium iodide were prepared in five steps from 4-dimethylaminophenyl-propargyl aldehyde and the corresponding lithium acetylide. When bound to DNA, all of the dyes absorb at wavelengths >600nm, which avoids the hemoglobin band I maximum at 575nm. The binding of the series of dyes to double-stranded DNA was examined spectrophotometrically and by isothermal titration calorimetry to determine binding constants, by a topoisomerase I DNA unwinding assay, by competition dialysis with [poly(dGdC)](2) and [poly(dAdT)](2), and by ethidium bromide displacement studies to examine propensities for intercalation, and by circular dichroism studies. The dyes were found to show mixed binding modes.

We report the design, synthesis using nanochemistry, and characterization of a novel multifunctional polymeric micelle-based nanocarrier system, which demonstrates combined function of magnetophoretically guided drug delivery together with light-activated photodynamic therapy. Specifically, the nanocarrier consists of polymeric micelles of diacylphospholipid-poly(ethylene glycol) (PE-PEG) coloaded with the photosensitizer drug 2-[1-hexyloxyethyl]-2-devinyl pyropheophorbide-a (HPPH), and magnetic Fe3O4 nanoparticles. The nanocarrier shows excellent stability and activity over several weeks. The physicochemical characterizations have been carried out by transmission electron micrography and optical spectroscopy. An efficient cellular uptake has been confirmed with confocal laser scanning microscopy. The loading efficiency of HPPH is practically unaffected upon coloading with the magnetic nanoparticles, and its phototoxicity is retained. The magnetic response of the nanocarriers was demonstrated by their magnetically directed delivery to tumor cells in vitro. The magnetophoretic control on the cellular uptake provides enhanced imaging and phototoxicity. These multifunctional nanocarriers demonstrate the exciting prospect offered by nanochemistry for targeting photodynamic therapy.

Several thio and seleno analogues of tetramethylrosamine (TMR) were prepared. Thio derivatives of TMR have absorption maxima near 570 nm, while seleno derivatives of TMR have absorption maxima near 580 nm. The 3- or 4-N,N-dimethylaminophenyl substituent in the 9-position greatly increases internal conversion, which lowers quantum yields for fluorescence and the generation of singlet oxygen. Thio and seleno analogues of TMR are effective photosensitizers against chemosensitive AUXB1 cells in vitro and against multidrug-resistant CR1R12 cells in vitro, which have been treated with verapamil. The CR1R12 cells accumulated significantly lower concentrations of the photosensitizers relative to the AUXB1 cells presumably due to the expression of P-glycoprotein (Pgp) in the CR1R12 cells. Following treatment with 5 x 10(-5) M verapamil, the uptake in CR1R12 cells of several fluorescent thio analogues of TMR is comparable to that observed for the chemosensitive AUXB1 cells.

21,23-Dithiaporphyrins (2-10) were designed and prepared as analogues of 5,20-diphenyl-10,15-bis(4-carboxylatomethoxy)phenyl-21,23-dithiaporphyrin (1) to examine the impact of steric bulk at the 5- and 20-meso positions as well as the impact of symmetry. Changes at the meso positions had minimal impact on the UV-vis-near-IR absorption spectra, quantum yields for the generation of singlet oxygen, and quantum yields for fluorescence and some impact on values of the octanol/water partition coefficient. Of the compounds 1-10, 5-phenyl-20-(2-thienyl)-10,15-bis-(4-carboxylatomethoxy-phenyl)-21,23-dithiaporphyrin (3) showed the greatest phototoxicity toward cultured R3230AC cells, with 68% cell kill at 1 x 10(-7)M and irradiation with 5J cm(-2) of 350-750 nm light. Results in this study suggest that smaller substituents on the meso ring and less symmetrical compounds are more effective as photosensitizers than compounds with two bulky substituents at adjoining meso sites and a higher symmetry. The mitochondria appear to be involved in the process of phototoxicity as determined by the inhibition of whole cell cytochrome c oxidase activity in cells treated with 3 and light. No impact upon mitochondrial cytochrome c oxidase activity was observed in cells treated with 3 and no light. Fluorescence microscopy studies suggest that the mitochondria are not initial sites of accumulation of 3.

A method is presented for the preparation of a biocompatible ferrofluid containing dye-functionalized magnetite nanoparticles that can serve as fluorescent markers. This method entails the surface functionalization of magnetite nanoparticles using citric acid to produce a stable aqueous dispersion and the subsequent binding of fluorescent dyes to the surface of the particles. Several ferrofluid samples were prepared and characterized using Fourier transform infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS), thermogravimetric analysis (TGA), BET surface area analysis, transmission electron microscopy (TEM), and SQUID magnetometry. In addition, confocal fluorescence microscopy was used to study the response of the fluorescent nanoparticles to an applied magnetic field and their uptake by cells in vitro. Results are presented on the distribution of particle sizes, the fluorescent and magnetic properties of the nanoparticles, and the nature of their surface bonds. Biocompatible ferrofluids with fluorescent nanoparticles enable optical tracking of basic processes at the cellular level combined with magnetophoretic manipulation and should be of substantial value to researchers engaged in both fundamental and applied biomedical research.

This article reports a multidisciplinary approach to produce fluorescently labeled organically modified silica nanoparticles as a nonviral vector for gene delivery and biophotonics methods to optically monitor intracellular trafficking and gene transfection. Highly monodispersed, stable aqueous suspensions of organically modified silica nanoparticles, encapsulating fluorescent dyes and surface functionalized by cationic-amino groups, are produced by micellar nanochemistry. Gel-electrophoresis studies reveal that the particles efficiently complex with DNA and protect it from enzymatic digestion of DNase 1. The electrostatic binding of DNA onto the surface of the nanoparticles, due to positively charged amino groups, is also shown by intercalating an appropriate dye into the DNA and observing the Forster (fluorescence) resonance energy transfer between the dye (energy donor) intercalated in DNA on the surface of nanoparticles and a second dye (energy acceptor) inside the nanoparticles. Imaging by fluorescence confocal microscopy shows that cells efficiently take up the nanoparticles in vitro in the cytoplasm, and the nanoparticles deliver DNA to the nucleus. The use of plasmid encoding enhanced GFP allowed us to demonstrate the process of gene transfection in cultured cells. Our work shows that the nanomedicine approach, with nanoparticles acting as a drug-delivery platform combining multiple optical and other types of probes, provides a promising direction for targeted therapy with enhanced efficacy as well as for real-time monitoring of drug action.