A Tumor-Targeting Near-Infrared Heptamethine Cyanine Photosensitizer with Twisted Molecular Structure for Enhanced Imaging-Guided Cancer Phototherapy

In recent years, cancer phototherapy has been extensively studied as noninvasive cancer treatment. To present efficient recognition toward cancer cells, most photosensitizers (PSs) are required to couple with tumor-targeted ligands. Interestingly, the heptamethine cyanine IR780 displays an intrinsic tumor-targeted feature even without modification. However, the photothermal efficacy and photostability of IR780 are not sufficient enough for clinical use. Herein, we involve a twisted structure of tetraphenylethene (TPE) between two molecules of IR780 to improve the photothermal conversion efficiency (PCE). The obtained molecule T780T shows strong near-infrared (NIR) fluorescence and improved PCE (38.5%) in the dispersed state. Also, the photothermal stability and ROS generation capability of T780T at the NIR range (808 nm) are both promoted. In the aqueous phase, the T780T was formulated into uniform nanoaggregates (∼200 nm) with extremely low fluorescence and PTT response, which would reduce in vivo imaging background and side effect of PTT response in normal tissues. After intravenous injection into tumor-bearing mice, the T780T nanoaggregates display high tumor accumulation and thus remarkably inhibit the tumor growth. Moreover, the enhanced photostability of the T780T allows for twice irradiation after one injection and leads to more significant tumor inhibition. In summary, our study presents a tumor-targeted small-molecule PS for efficient cancer therapy and brings a new design of heptamethine cyanine PS for potential clinical applications.

Photoacoustic imaging of elevated glutathione in models of lung cancer for companion diagnostic applications

Companion diagnostics (CDx) are powerful tests that can provide physicians with crucial biomarker information that can improve treatment outcomes by matching therapies to patients. Here, we report a photoacoustic imaging-based CDx (PACDx) for the selective detection of elevated glutathione (GSH) in a lung cancer model. GSH is abundant in most cells, so we adopted a physical organic chemistry approach to precisely tune the reactivity to distinguish between normal and pathological states. To evaluate the efficacy of PACDx in vivo, we designed a blind study where photoacoustic imaging was used to identify mice bearing lung xenografts. We also employed PACDx in orthotopic lung cancer and liver metastasis models to image GSH. In addition, we designed a matching prodrug, PARx, that uses the same SNAr chemistry to release a chemotherapeutic with an integrated PA readout. Studies demonstrate that PARx can inhibit tumour growth without off-target toxicity in a lung cancer xenograft model.

A multifunctional nano-delivery system enhances the chemo-co-phototherapy of tumor multidrug resistance via mitochondrial-targeting and inhibiting P-glycoprotein-mediated efflux

Despite the excellent progress of chemotherapy and phototherapy in tumor treatment, their effectiveness on multidrug-resistant (MDR) tumors is still unsatisfactory. One of the main obstacles is drug efflux caused by P-glycoprotein in MDR cells. Herein, we developed a nano-delivery system that combines a P-glycoprotein inhibitor with chemotherapy and phototherapy to overcome MDR. Briefly, the system is prepared by the self-assembly of a ROS-triggered doxorubicin prodrug (PTD) and mitochondrial-targeted D-α-tocopherol polyethyleneglycol succinate (TPP-TPGS), in which a photoactive drug, IR780, is encapsulated (PTD/TT/IR780). PTD/TT/IR780 can target the release of TPP-TPGS, doxorubicin and IR780 at the mitochondrial site of MDR cells through ROS trigger. D-α-Tocopherol polyethyleneglycol succinate (TPGS) is a P-glycoprotein inhibitor, which will reduce the efflux of doxorubicin and IR780 from MDR cells. Under irradiation of an 808 nm near-infrared laser, IR780 generates heat and ROS, causing mitochondrial damage and prompting MDR cell apoptosis. At the same time, ROS can reduce the ATP content, which inhibits the P-glycoprotein function. In addition, an increase in the ROS generates positive feedback, allowing more nanoparticles to be cleaved and further promoting payload release in MDR cells, thereby enhancing the synergistic efficacy of chemotherapy and phototherapy. The in vitro cellular assay showed that PTD/TT/IR780 significantly inhibited MDR cell proliferation at a very low drug concentration (IC50 = 0.27 μg mL-1 doxorubicin-equivalent concentration). In vivo animal experiments based on BALB/c nude mice bearing MCF-7/ADR tumors confirmed a superior antitumor efficacy and an excellent biosafety profile. These findings demonstrate that this multifunctional nanoplatform provides a new approach for the treatment of MDR tumors.

An Activatable Near-Infrared Fluorescence Probe for in Vivo Imaging of Acute Kidney Injury by Targeting Phosphatidylserine and Caspase-3

Renal-clearable and target-responsive near-infrared (NIR) fluorescent imaging probes have been promising for in vivo diagnosis of acute kidney injury (AKI). However, designing an imaging probe that is renal-clearable and concurrently responsive toward multiple molecular targets to facilitate early detection of AKI with improved sensitivity and specificity is challenging. Herein, by leveraging the receptor-mediated binding and retention effect along with enzyme-triggered fluorescence activation, we design and synthesize an activatable small-molecule NIR fluorescent probe (1-DPA2) using a "one-pot sequential click reaction" approach. 1-DPA2 can target both the externalized phosphatidylserine (PS) and active caspase-3 (Casp-3), two essential biomarkers of apoptosis, producing enhanced 808 nm NIR fluorescence and a high signal-to-background ratio (SBR) amenable to detecting the onset of cisplatin-induced AKI in mice as early as 24 h post-treatment with cisplatin. We not only monitor the gradual activation of Casp-3 in the kidney of mice upon AKI progression but also can report on the progressive recovery of kidney functions in AKI mice following N-acetyl-l-cysteine (NAC) therapy via real-time fluorescence imaging by 1-DPA2. This study demonstrates the ability of 1-DPA2 for longitudinal monitoring of renal cell apoptosis by concurrently targeting PS externalization and Casp-3 activation, which is efficient for early diagnosis of AKI and useful for prediction of potential drug nephrotoxicity as well as in vivo screening of anti-AKI drugs' efficacy.

Nanomaterials for Targeted Delivery of Agrochemicals by an All-in-One Combination Strategy and Deep Learning

The development of modern agriculture has prompted the greater input of herbicides, insecticides, and fertilizers. However, precision release and targeted delivery of these agrochemicals still remain a challenge. Here, a pesticide-fertilizer all-in-one combination (PFAC) strategy and deep learning are employed to form a system for controlled and targeted delivery of agrochemicals. This system mainly consists of three components: (1) hollow mesoporous silica (HMS), to encapsulate herbicides and phase-change material; (2) polydopamine (PDA) coating, to provide a photothermal effect; and (3) a zeolitic imidazolate framework (ZIF8), to provide micronutrient Zn2+ and encapsulate insecticides. Results show that the PFAC at concentration of 5 mg mL-1 reaches the phase transition temperature of 1-tetradecanol (37.5 °C) after 5 min of near-infrared (NIR) irradiation (800 nm, 0.5 W cm-2). The data of corn and weed are collected and relayed to deep learning algorithms for model building to realize object detection and further targeted weeding. In-field treatment results indicated that the growth of chicory herb was significantly inhibited when treated with the PFAC compared with the blank group after 24 h under NIR irradiation for 2 h. This system combines agrochemical innovation and artificial intelligence technology, achieves synergistic effects of weeding and insecticide and nutrient supply, and will potentially achieve precision and sustainable agriculture.

Rodlike Particles of Polydopamine-CdTe Quantum Dots: An Actuator As a Photothermal Agent and Reactive Oxygen Species-Generating Nanoplatform for Cancer Therapy

Herein, novel rodlike CdTe@MPA-PDA particles based on polydopamine (PDA) loaded with CdTe quantum dots (QDs) capped with mercaptopropionic acid (CdTe@MPA QDs) with atypical chemical features are evaluated as a potential actuator for photothermal therapy and oxidative stress induction. Under mild conditions established for the safe and efficient use of lasers, temperature increases of 10.2 and 7.8 °C, photothermal conversion efficiencies of 37.7 and 26.2%, and specific absorption rates of 99 and 69 W/g were obtained for CdTe@MPA-PDA and traditional PDA particles in water, respectively. The particles were set to interact with the human breast adenocarcinoma cell line MDA-MB-231. A significant cellular uptake with the majority of particles colocalized into the lysosomes was obtained at a concentration of 100 μg/mL after 24 h. Additionally, CdTe@MPA-PDA and CdTe@MPA QDs showed significantly different internalization levels and loading kinetics profiles. For the first time, the thermal lens technique was used to demonstrate the stability of particle-like CdTe@MPA-PDA after heating at pH 7 and their migration within the heating region due to the thermodiffusion effect. However, under acidic pH-type lysosomes, a performance decrease in heating was observed, and the chemical feature of the particles was damaged as well. Besides, the internalized rodlike CdTe@MPA-PDA notably enhanced the induction of oxidative stress compared with PDA alone and CdTe@MPA QDs in MDA-MB-231 cells initiating apoptosis. Combining these effects suggests that after meticulous optimizations of the conditions, the CdTe@MPA-PDA particles could be used as a photothermal agent under mild conditions and short incubation time, allowing cytoplasmatic subcellular localization. On the other hand, the same particles act as cell killers by triggering reactive oxygen species after a longer incubation time and lysosomal subcellular localization due to the pH effect on the chemical morphology features of the CdTe@MPA-PDA particles.

Survey of X-ray induced Cherenkov excited fluorophores with potential for human use

X-ray induced molecular luminescence (XML) is a phenomenon that can be utilized for clinical, deep-tissue functional imaging of tailored molecular probes. In this study, a survey of common or clinically approved fluorophores was carried out for their megavoltage X-ray induced excitation and emission characteristics. We find that direct scintillation effects and Cherenkov generation are two possible ways to cause these molecules' excitation. To distinguish the contributions of each excitation mechanism, we exploited the dependency of Cherenkov radiation yield on X-ray energy. The probes were irradiated by constant dose of 6 MV and 18 MV X-ray radiation, and their relative emission intensities and spectra were quantified for each X-ray energy pair. From the ratios of XML, yield for 6 MV and 18 MV irradiation we found that the Cherenkov radiation dominated as an excitation mechanism, except for aluminum phthalocyanine, which exhibited substantial scintillation. The highest emission yields were detected from fluorescein, proflavin and aluminum phthalocyanine, in that order. XML yield was found to be affected by the emission quantum yield, overlap of the fluorescence excitation and Cherenkov emission spectra, scintillation yield. Considering all these factors and XML emission spectrum respective to tissue optical window, aluminum phthalocyanine offers the best XML yield for deep tissue use, while fluorescein and proflavine are most useful for subcutaneous or superficial use.

Rapid Ultrastructural Changes in the PSD and Surrounding Membrane after Induction of Structural LTP in Single Dendritic Spines

The structural plasticity of dendritic spines is considered to be an important basis of synaptic plasticity, learning, and memory. Here, we induced input-specific structural LTP (sLTP) in single dendritic spines in organotypic hippocampal slices from mice of either sex and performed ultrastructural analyses of the spines using efficient correlative light and electron microscopy. We observed reorganization of the PSD nanostructure, such as perforation and segmentation, at 2-3, 20, and 120 min after sLTP induction. In addition, PSD and nonsynaptic axon-spine interface (nsASI) membrane expanded unevenly during sLTP. Specifically, the PSD area showed a transient increase at 2-3 min after sLTP induction. The PSD growth was to a degree less than spine volume growth at 2-3 min and 20 min after sLTP induction but became similar at 120 min. On the other hand, the nsASI area showed a profound and lasting expansion, to a degree similar to spine volume growth throughout the process. These rapid ultrastructural changes in PSD and surrounding membrane may contribute to rapid electrophysiological plasticity during sLTP.SIGNIFICANCE STATEMENT To understand the ultrastructural changes during synaptic plasticity, it is desired to efficiently image single dendritic spines that underwent structural plasticity in electron microscopy. We induced structural long-term potentiation (sLTP) in single dendritic spines by two-photon glutamate uncaging. We then identified the same spines at different phases of sLTP and performed ultrastructural analysis by using an efficient correlative light and electron microscopy method. We found that postsynaptic density undergoes dramatic modification in its structural complexity immediately after sLTP induction. Meanwhile, the nonsynaptic axon-spine interface area shows a rapid and sustained increase throughout sLTP. Our results indicate that the uneven modification of synaptic and nonsynaptic postsynaptic membrane might contribute to rapid electrophysiological plasticity during sLTP.

TPGS-Galactose-Modified Polydopamine Co-delivery Nanoparticles of Nitric Oxide Donor and Doxorubicin for Targeted Chemo-Photothermal Therapy against Drug-Resistant Hepatocellular Carcinoma

The lack of cancer cell specificity and the occurrence of multidrug resistance (MDR) are two major obstacles in the treatment of hepatocellular carcinoma (HCC). To tackle these challenges, a novel nanoparticle (NP)-based drug delivery system (DDS) with a core/shell structure consisted of d-α-tocopheryl polyethylene glycol 1000 succinate (TPGS)-galactose (Gal)/polydopamine (PDA) is fabricated. The NP is loaded with doxorubicin (DOX) and a nitric oxide (NO) donor N,N'-di-sec-butyl-N,N'-dinitroso-1,4-phenylenediamine (BNN) sensitive to heat to afford NO-DOX@PDA-TPGS-Gal. The unique binding of Gal to asialoglycoprotein receptor (ASGPR) and the pH-sensitive degradation of NP ensure the targeted transportation of NP into liver cells and the release of DOX in HCC cells. The near-infrared (NIR) light further facilitates DOX release and initiates NO generation from BNN due to the photothermal property of PDA. In addition to the cytotoxicity contributed by DOX, NO, and heat, TPGS and NO act as MDR reversal agents to inhibit P-glycoprotein (P-gp)-related efflux of DOX by HepG2/ADR cells. The combined chemo-photothermal therapy (chemo-PTT) by NO-DOX@PDA-TPGS-Gal thus shows potent anti-cancer activity against drug-resistant HCC cells in vitro and in vivo and significantly prolongs the life span of drug-resistant tumor-bearing mice. The present work provides a useful strategy for highly targeted and MDR reversal treatment of HCC.

Stimuli-Responsive Metal-Organic Framework on a Metal-Organic Framework Heterostructure for Efficient Antibiotic Detection and Anticounterfeiting

Stimuli-responsiveness is an important characteristic that show promising potential in various applications. Herein, a novel ZIF-8-on-Tb-dpn (H₃dpn = 5-(2',4'-dicarboxylphenyl)nicotic acid) heterostructure is constructed using a heteroepitaxial strategy combining the chemical-responsive (antibiotics) and light-responsive behaviors. The pyridine nitrogen of Tb-dpn acts as an anchor site for Zn²⁺, which helps to overcome the limit of lattice mismatch between two metal-organic frameworks (MOFs) and promotes the growth of ZIF-8 nanocrystals. Based on the synergy effect of two MOFs, ZIF-8-on-Tb-dpn exhibits an efficient turn-off response toward tetracycline and chloramphenicol via competitive absorption, Förster resonance energy transfer, and photoinduced electron transfer processes with limit of detection values of 5.6 and 37.6 nM, respectively, which are three- to -fivefold lower than those of Tb-dpn. Moreover, the nanocage of ZIF-8 is utilized to encapsulate photochromic spiropyran (SP) molecules and realize the reversible conversion between SP and merocyanine (MC) under visible light and ultraviolet light. The MC form is accompanied with strong adsorption at 555 nm, which can erase the emission of Tb³⁺. Therefore, a reversible invisible anticounterfeiting pattern is designed with SP ⊂ ZIF-8-on-Tb-dpn for information anticounterfeiting. The excellent stimuli-responsive ability makes the luminescent platform a potential candidate in luminescence applications.

Mussel-Inspired Immobilization of Photocatalysts with Synergistic Photocatalytic-Photothermal Performance for Water Remediation

The serious problem of pharmaceutical and personal care product pollution places great pressure on aquatic environments and human health. Herein, a novel coating photocatalyst was synthesized by adhering Ag-AgCl/WO₃/g-C₃N₄ (AWC) nanoparticles on a polydopamine (PDA)-modified melamine sponge (MS) through a facile layer-by-layer assembly method to degrade trimethoprim (TMP). The formed PDA coating was used for the anchoring of nanoparticles, photothermal conversion, and hydrophilic modification. TMP (99.9%; 4 mg/L) was removed in 90 min by the photocatalyst coating (AWC/PDA/MS) under visible light via a synergistic photocatalytic-photothermal performance route. The stability and reusability of the AWC/PDA/MS have been proved by cyclic experiments, in which the removal efficiency of TMP was still more than 90% after five consecutive cycles with a very little mass loss. Quantitative structure-activity relationship analysis revealed that the ecotoxicities of the generated intermediates were lower than those of TMP. Furthermore, the solution matrix effects on the photocatalytic removal efficiency were investigated, and the results revealed that the AWC/PDA/MS still maintained excellent photocatalytic degradation efficiency in several actual water and simulated water matrices. This work develops recyclable photocatalysts for the potential application in the field of water remediation.

Near-Infrared Photothermal/Photodynamic-in-One Agents Integrated with a Guanidinium-Based Covalent Organic Framework for Intelligent Targeted Imaging-Guided Precision Chemo/PTT/PDT Sterilization

Phototherapy holds great promise in the treatment of bacterial infections, especially the multidrug resistant bacterial infections. However, most therapeutic agents are based on the integration of individual photothermal agents and photosensitizers, always in the activated state, and generally lack bacterial specificity, resulting in uncertain pharmacokinetics and serious nonspecific damage to normal tissues. Herein, we report a pH-responsive nanoplatform with synergistic chemo-phototherapy function for smart fluorescence imaging-guided precision sterilization. pH reversible activated symmetric cyanine was designed and prepared as a bacterial-specific imaging unit and PTT/PDT-in-one agent. Meanwhile, a guanidinium-based covalent organic framework (COF) was employed as a nanocarrier and chemotherapy agent to build the intelligent nanoplatform via electrostatic self-assembly. The self-assembly of the PTT/PDT-in-one agent and the COF greatly improves the stability and blood circulation of the PTT/PDT-in-one agent and provides charge-reversed intelligent targeting ability. The developed smart nanoplatform not only enables bacterial-targeted imaging but also possesses chemo/PTT/PDT synergetic high-efficiency bactericidal effects with little side effects, showing great potential in practical applications.

Novel Multifunctional Stimuli-Responsive Nanoparticles for Synergetic Chemo-Photothermal Therapy of Tumors

In this study, a novel class of multifunctional responsive nanoparticles is designed and fabricated as drug nanocarriers for synergetic chemo-photothermal therapy of tumors. The proposed nanoparticles are composed of a thermo-/pH-responsive poly(N-isopropylacrylamide-co-acrylic acid) (PNA) nanogel core, a polydopamine (PDA) layer for photothermal conversion, and an outer folic acid (FA) layer as a targeting agent for the folate receptors on tumor cells. The fabricated nanoparticles show good biocompatibility and outstanding photothermal conversion efficiency. The proposed nanoparticles loaded with doxorubicin (DOX) drug molecules are stable under physiological conditions with low leakage of drugs, while rapidly release drugs in environments with low pH conditions and at high temperature. The experimental results show that the drug release process is mainly governed by Fickian diffusion. In vitro cell experimental results demonstrate that the PNA-DOX@PDA-FA nanoparticles can be phagocytized by 4T1 tumor cells and release drugs in tumor cell acidic environments, and confirm that the combined chemo and photothermal therapeutic efficacy of PNA-DOX@PDA-FA nanoparticles is higher than the photothermal therapeutic efficacy or the chemotherapeutic efficacy alone. The proposed multifunctional responsive nanoparticles in this study provide a novel class of drug nanocarriers as a promising tool for synergetic chemo-photothermal therapy of tumors.

Novel pH-Triggered Doxorubicin-Releasing Nanoparticles Self-Assembled by Functionalized β-Cyclodextrin and Amphiphilic Phthalocyanine for Anticancer Therapy

Cyclodextrins (CDs), as pharmaceutical excipients with excellent biocompatibility, non-immunogenicity, and low toxicity in vivo, are widely used to carry drugs by forming inclusion complexes for improving the solubility and stability of drugs. However, the limited space of CDs' lipophilic central cavity affects the loading of many drugs, especially with larger molecules. In this study, β-CDs were modified by acetonization to improve the affinity for the chemotherapy drug doxorubicin (DOX), and doxorubicin-adsorbing acetalated β-CDs (Ac-CD:DOX) self-assembled to nanoparticles, followed by coating with the amphiphilic zinc phthalocyanine photosensitizer ZnPc-(PEG)₅ for antitumor therapy. The final product ZnPc-(PEG)₅:Ac-CD:DOX was demonstrated to have excellent stability and pH-sensitive drug release characteristics. The cell viability and apoptosis assay showed synergistic cytotoxic effects of chemotherapy and phototherapy. The mechanism of cytotoxicity was analyzed in terms of intracellular reactive oxygen species, mitochondrial membrane potential, and subcellular localization. More importantly, in vivo experiments indicated that ZnPc-(PEG)₅:Ac-CD:DOX possessed significant tumor targeting, prominent antitumor activity, and less side effects. Our strategy expands the application of CDs as drug carriers and provides new insights into the development of CD chemistry.

68Ga-Labeled Magnetic-NIR Persistent Luminescent Hybrid Mesoporous Nanoparticles for Multimodal Imaging-Guided Chemotherapy and Photodynamic Therapy

Featured with a zero-autofluorescence background, superior signal-to-noise ratio, high sensitivity, and deep penetration ability, near-infrared persistent luminescence nanoparticle (NIR-PLNP)-based multimodal nanoprobes show great potential for full-scale noninvasive cancer diagnosis. However, direct synthesis of NIR-PLNP-based multimodal nanoprobes with high drug loading capacity to meet growing cancer theranostic demands remains a challenge. In this work, multifunctional hybrid mesoporous nanoparticles (HMNPs) that integrate NIR-PLNPs (Ga2O3:Cr3+, Nd3+), magnetic nanoparticles (Gd2O3), and radionuclides (68Ga) are designed and constructed via a large-pore (mesoporous silica nanoparticle) MSN-templated strategy. The ingenious composition design endows HMNPs with rechargeable NIR-PL, superior longitudinal relaxivity, and excellent radioactivity, making these versatile nanoparticles available for long-term in vivo NIR-PL imaging, magnetic resonance imaging (MRI), and positron emission tomography (PET) imaging. More importantly, the application of large-pore MSN templates maintains the mesoporous structure of HMNPs, promising excellent drug loading capacity of these nanoparticles. As a proof-of-concept, HMNPs loaded with a high dose of DOX (chemotherapy agent) and Si-Pc (photosensitizer) are rationally designed for chemotherapy and NIR-PL-sensitized photodynamic therapy (PDT), respectively. Studies with mice tumor models demonstrate that the DOX/Si-Pc-loaded HMNPs possess excellent cancer cell killing ability and an outstanding tumor suppression effect without systemic toxicity. This work shows the great potential of HMNPs as an "all-in-one" nanotheranostic tool for multimodal NIR-PL/MR/PET imaging-guided chemotherapy and NIR-PL-sensitized photodynamic cancer therapy and provides an innovative paradigm for the development of NIR-PLNP-based nanoplatforms in cancer theranostic.

Facile Synthesis of Cyclic Peptide-Phthalocyanine Conjugates for Epidermal Growth Factor Receptor-Targeted Photodynamic Therapy

A facile procedure for in situ peptide cyclization and phthalocyanine conjugation was developed by utilizing a bifunctional linker incorporated with a bis(bromomethyl)benzene unit and a cyclopentadiene moiety. These functional groups facilitated the nucleophilic substitution with the two cysteine residues of the linear peptides followed by the Diels-Alder reaction with the maleimide moiety attached to a zinc(II) phthalocyanine. With this approach, three cyclic peptide-phthalocyanine conjugates were prepared in 20-26% isolated yield via a one-pot procedure. One of the conjugates containing a cyclic form of the epidermal growth factor receptor (EGFR)-binding peptide sequence CMYIEALDKYAC displayed superior features as an advanced photosensitizer. It showed preferential uptake by two EGFR-positive cancer cell lines (HT29 and HCT116) compared with two EGFR-negative counterparts (HeLa and HEK293), resulting in significantly higher photocytotoxicity. Intravenous administration of this conjugate into HT29 tumor-bearing nude mice resulted in selective localization in tumor and effective inhibition of tumor growth upon photodynamic treatment.

Construction of a Mesoporous Polydopamine@GO/Cellulose Nanofibril Composite Hydrogel with an Encapsulation Structure for Controllable Drug Release and Toxicity Shielding

The development of intelligent and multifunctional hydrogels having photothermal properties, good mechanical properties, sustained drug release abilities with low burst release, antibacterial properties, and biocompatibility is highly desirable in the biomaterial field. Herein, mesoporous polydopamine (MPDA) nanoparticles wrapped with graphene oxide (GO) were physically cross-linked in cellulose nanofibril (CNF) hydrogel to obtain a novel MPDA@GO/CNF composite hydrogel for controllable drug release. MPDA nanoparticles exhibited a high drug loading ratio (up to 35 wt %) for tetracycline hydrochloride (TH). GO was used to encapsulate MPDA nanoparticles for extending the drug release time and reinforcing the physical strength of the obtained hydrogel. The mechanical strength of the as-fabricated MPDA@GO/CNF composite hydrogel was five times greater compared to that of the pure CNF hydrogel. Drug release experiments demonstrated that burst release behavior was significantly reduced by adding MPDA@GO. The drug release time of the MPDA@GO/CNF composite hydrogel was 3 times and 7.2 times longer than that of the polydopamine/CNF hydrogel and pure CNF hydrogel, respectively. The sustained and controlled drug release behaviors of the composite hydrogel were highly dependent on the proportion of MPDA and GO. Moreover, the rate of drug release could be accelerated by near-infrared (NIR) light irradiation and pH value change. The drug release kinetics of the as-prepared composite hydrogel was well described by the Korsmeyer-Peppas model, and the drug release mechanism of TH from the composite hydrogel was anomalous transport. Importantly, this carefully designed MPDA@GO/CNF composite hydrogel showed good biocompatibility through an in vitro cytotoxicity test. In particular, the toxicity of GO was well shielded by the CNF hydrogel. Therefore, this novel MPDA@GO/CNF composite hydrogel with an encapsulation structure for controllable drug release and toxicity shielding of GO could be used as a very promising controlled drug delivery carrier, which may have potential applications for chemical and physical therapies.

Laser-induced graphitization of polydopamine leads to enhanced mechanical performance while preserving multifunctionality

Polydopamine (PDA) is a simple and versatile conformal coating material that has been proposed for a variety of uses; however in practice its performance is often hindered by poor mechanical properties and high roughness. Here, we show that blue-diode laser annealing dramatically improves mechanical performance and reduces roughness of PDA coatings. Laser-annealed PDA (LAPDA) was shown to be >100-fold more scratch resistant than pristine PDA and even better than hard inorganic substrates, which we attribute to partial graphitization and covalent coupling between PDA subunits during annealing. Moreover, laser annealing provides these benefits while preserving other attractive properties of PDA, as demonstrated by the superior biofouling resistance of antifouling polymer-grafted LAPDA compared to PDA modified with the same polymer. Our work suggests that laser annealing may allow the use of PDA in mechanically demanding applications previously considered inaccessible, without sacrificing the functional versatility that is so characteristic of PDA.

Width-Consistent Mesoporous Silica Nanorods with a Precisely Controlled Aspect Ratio for Lysosome Dysfunctional Synergistic Chemotherapy/Photothermal Therapy/Starvation Therapy/Oxidative Therapy

Although differently shaped mesoporous silica is widely studied, the formation of width-consistent mesoporous silica nanorods (MSNRs) with a precisely controlled aspect ratio (AR: length/width) is challenging and has not been reported. Herein, width-consistent (100 nm) MSNRs with ARs of 2, 3, 4, 6, 8, and 10 were obtained by increasing the concentrations while maintaining the molar ratio of cetyltrimethylammonium bromide (CTAB) and tetraethyl orthosilicate (TEOS). The results demonstrated that the as-prepared MSNR with an AR of 6 (AR6) possesses high cellular-uptake efficiency and drug-loading capacity. Thus, AR6-based cancer-cell-targeting nanosystems were designed. These nanosystems encapsulated doxorubicin (DOX) into the porous channel of AR6, adsorbed glucose oxidase (GOx), and then formed a polydopamine (PDA) layer for Siramesine (Siram, a lysosome dysfunctional drug) adsorption and folic acid modification. In this design, the PDA shell could prevent the leakage of loading components and keep the activity of GOx during delivery while achieving an on-demand drug release in the targeted location and photothermal therapy under near-infrared irradiation. The increase in temperature was highly beneficial for elevating the catalytic efficiency of GOx, accelerating the consumption of intracellular glucose, and generating a relatively high level of cytotoxic H₂O₂, all of which enhanced starvation and oxidative therapies. Siram was employed to inhibit lysosomal metabolism and accompany GOx to reach a dual-enhanced starvation therapy effect. In addition, DOX entered the nucleus and altered DNA for chemotherapy. The results showed that the nanosystems have superior therapeutic efficacy against cancer cells and not much toxicity to normal cells. Therefore, this study provides a novel strategy for lysosome dysfunctional synergistic chemotherapy/photothermal therapy/starvation therapy/oxidative therapy based on MSNR.

Multifunctional siRNA-Laden Hybrid Nanoplatform for Noninvasive PA/IR Dual-Modal Imaging-Guided Enhanced Photogenetherapy

Small interfering RNA (siRNA)-induced gene therapy has been recognized as a promising avenue for effective cancer treatment, while easy enzymatic degradation, poor transfection efficiency, nonspecific biodistribution, and uncontrolled release hinder its extensive clinical applications. Zeolitic imidazolate frameworks-8 (ZIF-8) have emerged as promising drug carriers without an in-depth exploration in programmable siRNA delivery. Herein, we report a multifunctional PDAs-ZIF-8 (PZ) nanoplatform for delivering siRNA with combined photothermal therapy (PTT) and gene therapy (GT) via the noninvasive guidance of photoacoustic (PA)/near-infrared (IR) dual-modal imaging. The ingenious PZ nanocarriers mediated the tumor-specific accumulation of therapeutic siRNA without undesired degradation and preleakage. The pH-responsive ZIF-8 decomposed in an acidic tumor microenvironment that was accompanied by the release of siRNA payloads for cleaving target mRNA in gene silencing therapy. Meanwhile, the polydopamine nanoparticles (PDAs) could simultaneously serve as a powerful noninvasive PA/IR imaging contrast agent and versatile photothermal agent for diagnosis-guided photogenetherapy. The systematic in vitro and in vivo experimental explorations demonstrated that our PDAs-siRNA-ZIF-8 (PSZ) could greatly enhance the therapeutic efficiency as compared with the corresponding PTT or GT monotherapy. This work holds great potential to advance the development of more intelligent diagnosis and therapeutic strategies, thus supplying promising smart nanomedicines in the near future.

Near-infrared/pH dual-responsive nanocomplexes for targeted imaging and chemo/gene/photothermal tri-therapies of non-small cell lung cancer

Combination therapy offers promising opportunities for treating advanced non-small cell lung cancer (NSCLC). Here, we established a chitosan-based nanocomplex CE7Q/CQ/S to deliver molecular-targeted drug erlotinib (Er), Survivin shRNA-expressing plasmid (SV), and photothermal agent heptamethine cyanine dye (Cy7) in one platform for simultaneous near-infrared (NIR) fluorescence imaging and triple-combination therapy of NSCLC bearing epidermal growth factor receptor (EGFR) mutations. The obtained CE7Q/CQ/S exhibited favorable photothermal effects, good DNA binding ability, and pH/NIR dual-responsive release behaviors. The conjugated Er could mediate specific delivery of Cy7 to EGFR-mutated NSCLC cells to enable targeted NIR fluorescence imaging and photothermal therapy (PTT). The in vitro and in vivo results showed that downregulation of Survivin expression and the photothermal effects could act synergistically with Er to induce satisfactory anticancer effects in either Er-sensitive or Er-resistant EGFR-mutated NSCLC cells. By integrating chemo/gene/photothermal therapies into one theranostic nanoplatform, CE7Q/CQ/S could significantly suppress EGFR-mutated NSCLC, indicating its potential use in treating NSCLC. STATEMENT OF SIGNIFICANCE: The development of epidermal growth factor receptor tyrosine kinase inhibitors (EGFR-TKIs) has improved overall survival in patients with NSCLC driven by EGFR mutations. Unfortunately, the emergence of acquired resistance of EGFR-TKIs is almost inevitable after treatment. Here, we constructed a NIR/pH dual-responsive nanocomplex CE7Q/CQ/S based on chitosan which could integrate targeted near-infrared fluorescence imaging and chemo/gene/phototheramal tri-therapies together. We found that CE7Q/CQ/S possessed a promising outcome in fighting against EGFR-mutated NSCLC. The inhibition of Survivin expression and the application of photothermal therapy could act synergistically with erlotinib and reverse erlotinib resistance. The results of this work suggested that this chitosan-based combination therapeutic nanoplatform could be a promising candidate for NSCLC treatment.

A sequential targeting nanoplatform for anaplastic thyroid carcinoma theranostics

Effective accumulation of nanoparticles (NPs) in tumor regions is one of the major motivations in nanotechnology research and that the establishment of an efficient targeting nanoplatform for the treatment of malignant tumors is urgently needed for theranostic applications. In this study, we engineered multifunctional sequential targeting NPs for achieving synergistic antiangiogenic photothermal therapy (PTT) and multimodal imaging-guided diagnosis for anaplastic thyroid carcinoma (ATC) theranostics. Antibody bevacizumab with an affinity towards vascular endothelial growth factor (VEGF) on the tumor cell surface was conjugated onto the surface of polymer NPs for VEGF targeting and antiangiogenic therapy. Encapsulated IR825 was employed as a photothermal agent (PTA) with a mitochondrial targeting capability, which further cascades NPs into mitochondria to enhance hyperthermic efficiency in the ablation of tumor cells. Importantly, the combination of bevacizumab and IR825 in a single nanosystem achieved desirable accumulations of NPs and that sequential targeted PTT combined with antiangiogenesis significantly promoted the therapeutic efficiency in eradicating tumors by near-infrared (NIR) laser irradiation. Furthermore, these NPs are extraordinary contrast agents for photoacoustic, ultrasound and fluorescence imaging applications, providing multimodal imaging capabilities for therapeutic monitoring and a precise diagnosis. Therefore, this multifunctional nanoplatform provides a promising theranostic strategy for extremely malignant ATC. STATEMENT OF SIGNIFICANCE: Anaplastic thyroid carcinoma (ATC), with extremely aggressive behavior, lacks a satisfactory therapeutic method and a comprehensive early diagnostic strategy. Herein, we successfully synthesized a sequential targeting nanoplatform (IR825@Bev-PLGA-PFP NPs) with theranostic function, which specifically binds to VEGF on the tumor cell surface and further cascades into mitochondria to achieve effective accumulation of NPs in the tumor regions. As a result, it solves the urgent demand for ATC detection and therapy. By breaking the limitation of traditional target, such as low efficacy and frequent recurrence as the results of low accumulation, sequential targeting combined with synergistic antiangiogenic PTT completely eradicates tumors without any residual tissue and side effect. Therefore, this strategy paves a solid way for further investigation in the theranostic progressing of ATC.

pH and Ultrasound Dual-Responsive Polydopamine-Coated Mesoporous Silica Nanoparticles for Controlled Drug Delivery

A pH- and ultrasound dual-responsive drug release pattern was successfully achieved using mesoporous silica nanoparticles (MSNs) coated with polydopamine (PDA). In this paper, the PDA shell on the MSN surface was obtained through oxidative self-polymerization under the alkaline condition. The morphology and structure of this composite nanoparticle were fully characterized by a series of analyses, such as infrared (IR), transmission electron microscopy, and thermogravimetric analysis. Doxorubicin hydrochloride (DOX)-loaded composite nanoparticles were used to study the performances of responsive drug storage/release behavior, and this kind of hybrid material displayed an apparent pH response in DOX releasing under the acidic condition. Beyond that, upon high-intensity focused ultrasound exposure, loaded DOX in composite nanoparticles was successfully triggered to release from pores because of the ultrasonic cavitation effect, and the DOX-releasing pattern could be optimized into a unique pulsatile fashion by switching the on/off status. From the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay, it was observed that our blank nanoparticles showed no toxicity to HeLa cells, but DOX-loaded nanoparticles could inhibit the growth of tumor cells. Furthermore, these composite nanoparticles displayed an effective near-IR photothermal conversion capability with a relatively high conversion efficiency (∼37%). These as-desired drug delivery carriers might have a great potential for future cancer treatment that combine the chemotherapy and photothermal therapy.

Synthesis and characterization of a photocleavable collagen-like peptide

A 34-amino acid long collagen-like peptide rich in proline, hydroxyproline, and glycine, and with four photoreactive N-acyl-7-nitroindoline units incorporated into the peptide backbone was synthesized by on-resin fragment condensation. Its circular dichroism supports a stable triple helix structure. The built-in photochemical function enables the decomposition of the peptide into small peptide fragments by illumination with UV light of 350 nm in aqueous solution. Illumination of a thin film of the peptide, or a thin film of a photoreactive amino acid model compound containing a 5-bromo-7-nitroindoline moiety, with femtosecond laser light at 710 nm allows for the creation of well-resolved micropatterns. The cytocompatibility of the peptide was demonstrated using human mesenchymal stem cells and mouse embryonic fibroblasts. Our data show that the full-length peptide is cytocompatible as it can support cell growth and maintain cell viability. In contrast, the small peptide fragments created by photolysis are somewhat cytotoxic and therefore less cytocompatible. These data suggest that biomimetic collagen-like photoreactive peptides could potentially be used for growing cells in 2D micropatterns based on patterns generated by photolysis prior to cell growth.

Polydopamine-Coated TiO2 Nanotubes for Selective Photocatalytic Oxidation of Benzyl Alcohol to Benzaldehyde Under Visible Light

TiO2 nanotube arrays grown by anodization were coated with thin layers of polydopamine as visible light sensitizer. The PDA-coated TiO2 scaffolds were used as photocatalyst for selective oxidation of benzyl alcohol under monochromatic irradiation at 473 nm. Benzaldehyde was selectively formed and no by-products could be detected. A maximized reaction yield was obtained in O2-saturated acetonitrile. A mechanism is proposed that implies firstly the charge carrier generation in polydopamine as a consequence of visible light absorption. Secondly, photo-promoted electrons are injected in TiO2 conduction band, and subsequently transferred to dissolved O2 to form O*2- radicals. These radicals react with benzyl alcohol and lead to its selective dehydrogenation oxidation towards benzaldehyde.

The lifetime of the triplet excited state and modulation characteristics of all-optical switching in phenoxy-phthalocyanines liquid

We present our experimental results on the measurements of excited state dynamics in 2, 9, 16, 23-phenoxy-phthalocyanine (Pc1) and 2, 9, 16, 23-phenoxy-phthalocyanine-zinc (Pc2) using the pump-probe experiment. The results show that the lifetime of the first triplet excited state of the Pc2 longer than Pc1. The lifetimes of the triplet excited state for Pc2 and Pc1 are 12.8 μs and 10.1 μs at the same intensity, respectively. Moreover, analysis of modulation characteristics of all-optical switching (A-OS) shows that the stronger the light intensity of the pump light is, the smaller the normalized transmittance is, and the lower the A-OS response time is. The consequences of such short lifetimes are also discussed in view of the strong A-OS properties of these molecules.

Zinc(II) phthalocyanines immobilized in mesoporous silica Al-MCM-41 and their applications in photocatalytic degradation of pesticides

In the present study the authors investigated a set of three new zinc(II) phthalocyanines (zinc(II) tetranitrophthalocyanine (ZnTNPc), zinc(II) tetra(phenyloxy)phthalocyanine (ZnTPhOPc) and the tetraiodide salt of zinc(II)tetra(N,N,N-trimethylaminoethyloxy) phthalocyaninate (ZnTTMAEOPcI)) immobilized into Al-MCM-41 prepared via ship-in-a-bottle methodology. The samples were fully characterized by diffuse reflectance-UV-vis spectroscopy (DRS-UV-vis), luminescence, thermogravimetric analysis (TG/DSC), N(2) adsorption techniques and elemental analysis. A comparative study was made on the photocatalytic performance upon irradiation within the wavelength range 320-460nm of these three systems in the degradation of pesticides fenamiphos and pentachlorophenol. ZnTNPc@Al-MCM-41 and ZnTTMAEOPcI@Al-MCM-41 were found to be the most active systems, with the best performance observed with the immobilized cationic phthalocyanine, ZnTTMAEOPcI@Al-MCM-41. This system showed high activity even after three photocatalytic cycles. LC-MS product characterization and mechanistic studies indicate that singlet oxygen ((1)O(2)), produced by excitation of these immobilized photosensitizers, is a key intermediate in the photocatalytic degradation of both pesticides.

Ultrasound assisted, ruthenium-exchanged FAU-Y zeolite catalyzed alkylation of indoles with epoxides under solvent free conditions

Ruthenium-exchanged FAU-Y zeolite (RuY) was used as a recyclable catalyst for regioselective ring-opening of epoxides with indoles under irradiation of sonic waves. It was found that a solvent free process, under the above mentioned conditions provides good yields of the desired 3-alkylated indole derivatives.

Sonochemical multi-component synthesis of spirooxindoles

New and efficient multi-component methods have been developed for the synthesis of spirooxindoles in the presence of a catalytic amount of p-TSA as an inexpensive and available catalyst in EtOH under ultrasound irradiation. The method is simple, starts from readily accessible commercial starting materials, and provides biologically interesting products in good yields and short reaction times.

Ultrasound promoted clay catalyzed efficient and one pot synthesis of substituted oxindoles

A simple facile, one-pot synthesis of oxindoles in reasonable purity is reported via intramolecular Friedal-Craft cyclization. Clay KSF is an inexpensive, efficient and mild catalyst for the synthesis of substituted oxindoles by the reaction of chloroacetyl chloride and various anilines under the influence of ultrasonic irradiation under solvent-free conditions. The remarkable advantages of this method are the simple experimental procedures, short reaction times, high yields of products, suitability for a wide variety of substituents, and the green aspects through the avoidance of toxic catalyst and solvents.

Cyanobacteria and ultraviolet radiation (UVR) stress: mitigation strategies

Cyanobacteria are primitive photosynthetic oxygen-evolving prokaryotes that appeared on the Earth when there was no ozone layer to protect them from damaging ultraviolet radiation (UVR). UVR has both direct and indirect effects on the cyanobacteria due to absorption by biomolecules and UVR-induced oxidative stress, respectively. However, these organisms have developed several lines of mitigation strategies/defense mechanisms such as avoidance, scavenging, screening, repair and programmed cell death to counteract the damaging effects of UVR. This review presents an update on the effects of UVR on cyanobacteria and the defense mechanisms employed by these prokaryotes to withstand UVR stress. In addition, recent developments in the field of molecular biology of UV-absorbing compounds such as mycosporine-like amino acids and scytonemin, are also added and the possible role of programmed cell death, signal perception as well their transduction under UVR stress is being discussed.

Photocatalytic degradation of indole in a circulating upflow reactor by UV/TiO2 process--influence of some operating parameters

The present work involves the photocatalytic degradation of indole on a recirculating reactor. The effects of various factors as initial concentration of indole, catalyst-loading, pH, agitation and flow rate of the solution on the photodegradation were examined. The experimental results indicate that the optimal pH for indole elimination is about 6-7; the effect of catalyst loading shows an optimal value (1g/L) which is necessary to degrade indole; the increase of recirculating rate leads to a decrease of degradation rate due to the reduction of the residence time; the agitation speed has a slight influence on the indole degradation by improving the mass transfer step. Finally, L-H model was used to fit experimental results concerning the influence of experimental data. L-H model constants' were determined also.

A microwave assisted intramolecular-furan-Diels-Alder approach to 4-substituted indoles

The key steps of a versatile new protocol for the convergent synthesis of 3,4-disubstituted indoles are the addition of an alpha-lithiated alkylaminofuran to a carbonyl compound, a microwave-accelerated intramolecular Diels-Alder cycloaddition and an in situ double aromatization reaction.

Enhancement of ultrasonically induced cell damage by phthalocyanines in vitro

In this work, erythrocytes from carp were used as a nucleated cell model to test the hypothesis that the phthalocyanines (zinc--ZnPc and chloroaluminium -AlClPc) enhance ultrasonically induced damage in vitro. In order to confirm and complete our earlier investigation, the influence of ultrasound (US) and phthalocyanines (Pcs) on unresearched cellular components, was studied. Red blood cells were exposed to 1 MHz continuous ultrasound wave (0.61 and/or 2.44 W/cm(2)) in the presence or absence of phthalocyanines (3 microM). To identify target cell damage, we studied hemolysis, membrane fluidity and morphology of erythrocytes. To demonstrate the changes in the fluidity of plasma membrane we used the spectrofluorimetric methods using two fluorescence probes: 1-[4-(trimethylamino)phenyl]-6-phenyl-1,3,5,-hexatriene (TMA-DPH) and 1,6-diphenyl-1,3,5-hexatriene (DPH). The effect of US and Pcs on nucleated erythrocytes morphology was estimated on the basis of microscopic observation. The enhancement of ultrasonically induced membrane damage by both phthalocyanines was observed in case of hemolysis, and membrane surface fluidity, in comparison to ultrasound. The authors also observed changes in the morphology of erythrocytes. The obtained results support the hypothesis that the Pcs enhance ultrasonically induced cell damage in vitro. Furthermore, the influence of ultrasound on phthalocyanines (Pcs) in medium and in cells was tested. The authors observed changes in the phthalocyanines absorption spectra in the medium and the increase in the intensity of phthalocyanines fluorescence in the cells. These data can suggest changes in the structure of phthalocyanines after ultrasound action.

An efficient and practical synthesis of 2-((1H-indol-3-yl)(aryl)methyl)malononitriles under ultrasound irradiation

Synthesis of 2-((1H-indol-3-yl)(aryl)methyl)malononitrile via the Michael addition of indole with various arylmethylenemalononitriles was carried out in good yields using anhydrous zinc chloride as the catalyst under ultrasound irradiation.

Toxicity change patterns and its mechanism during the degradation of nitrogen-heterocyclic compounds by O(3)/UV

Many nitrogen-heterocyclic compounds (NHCs) are toxic and recalcitrant contaminants that need to be degraded by advanced oxidation processes. In this study, quinoline, isoquinoline and indole were selected to investigate their toxicity patterns during the degradation by O(3)/UV. It was found that for all the three NHCs there was some H(2)O(2) formed in the degradation process, which caused the sharp increase of toxicity to Photobacterium phosphoreum. The toxicity decreasing patterns after H(2)O(2) elimination were different for quinoline (or isoquinoline) and indole. After H(2)O(2) elimination, for quinoline or isoquinoline the toxicity decreased concurrently with the decrease of its concentration, while for indole the toxicity lagged behind its removal rate. The rate constant of the NHC with O(3) (k(D)) was the decisive parameter of its toxicity pattern because of its critical role in determining the degradation rate of the NHC. Two quantitative structure-activity relationship equations for the k(D) values of simple NHCs and homocyclic aromatics were successfully established, which would be useful to predict their toxicity patterns.

Recurrent circuits in layer II of medial entorhinal cortex in a model of temporal lobe epilepsy

Patients and laboratory animal models of temporal lobe epilepsy display loss of layer III pyramidal neurons in medial entorhinal cortex and hyperexcitability and hypersynchrony of less vulnerable layer II stellate cells. We sought to test the hypothesis that loss of layer III pyramidal neurons triggers synaptic reorganization and formation of recurrent, excitatory synapses among layer II stellate cells in epileptic pilocarpine-treated rats. Laser-scanning photo-uncaging of glutamate focally activated neurons in layer II while excitatory synaptic responses were recorded in stellate cells. Photostimulation revealed previously unidentified, functional, recurrent, excitatory synapses between layer II stellate cells in control animals. Contrary to the hypothesis, however, control and epileptic rats displayed similar levels of recurrent excitation. Recently, hyperexcitability of layer II stellate cells has been attributed, at least in part, to loss of GABAergic interneurons and inhibitory synaptic input. To evaluate recurrent inhibitory circuits in layer II, we focally photostimulated interneurons while recording inhibitory synaptic responses in stellate cells. IPSCs were evoked more than five times more frequently in slices from control versus epileptic animals. These findings suggest that in this model of temporal lobe epilepsy, reduced recurrent inhibition contributes to layer II stellate cell hyperexcitability and hypersynchrony, but increased recurrent excitation does not.

Assembling a Mixed Phthalocyanine−Porphyrin Array in Aqueous Media through Host−Guest Interactions

A stable 1:1 host-guest complex is formed between a silicon(IV) phthalocyanine conjugated axially with two permethylated beta-cyclodextrin units and a tetrasulfonated porphyrin. The complex exhibits a light-harvesting property and works as an efficient photosensitizing system, killing HT29 human colon adenocarcinoma cells with an IC50 value of 0.09 microM. [structure: see text].

Theoretical Solar-to-Electrical Energy-Conversion Efficiencies of Perylene−Porphyrin Light-Harvesting Arrays

The efficiencies of organic solar cells that incorporate light-harvesting arrays of organic pigments were calculated under 1 sun of air mass 1.5 solar irradiation. In one set of calculations, photocurrent efficiencies were evaluated for porphyrin, phthalocyanine, chlorin, bacteriochlorin, and porphyrin-bis(perylene) pigment arrays of different length and packing densities under the assumption that each solar photon absorbed quantitatively yielded one electron in the external circuit. In another more realistic set of calculations, solar conversion efficiencies were evaluated for arrays comprising porphyrins or porphyrin-(perylene)2 units taking into account competitive excited-state relaxation pathways. A system of coupled differential equations for all reactions in the arrays was solved on the basis of previously published rate constants for (1) energy transfer between the perylene and porphyrin pigments, (2) excited-state relaxation of the perylene and porphyrin pigments, and (3) excited-state electron injection into the semiconductor. This formal analysis enables determination of the optimal number of pigments in an array for solar-to-electrical energy conversion. The optimal number of pigments depends on the molar absorption coefficient and the density at which the arrays can be packed on an electrode surface. Taken together, the ability to employ fundamental photophysical, kinetic, and structural parameters of modular molecular architectures in assessments of the efficiency of solar-to-electrical energy conversion should facilitate the design of molecular-based solar cells.

Tetrapyrrole Singlet Excited State Quenching by Carotenoids in an Artificial Photosynthetic Antenna

Two artificial photosynthetic antenna models consisting of a Si phthalocyanine (Pc) bearing two axially attached carotenoid moieties having either 9 or 10 conjugated double bonds are used to illustrate some of the function of carotenoids in photosynthetic membranes. Both models studied in toluene, methyltetrahydrofuran, and benzonitrile exhibited charge separated states of the type C*+-Pc*- confirming that the quenching of the Pc S1 state is due to photoinduced electron transfer. In hexane, the Pc S1 state of the 10 double bond carotenoid-Pc model was slightly quenched but the C*+-Pc*- transient was not spectroscopically detected. A semiclassical analysis of the data in hexane at temperatures ranging from 180 to 320 K was used to demonstrate that photoinduced electron transfer could occur. The model bearing the 10 double bond carotenoids exhibits biexponential fluorescence decay in toluene and in hexane, which is interpreted in terms of an equilibrium mixture of two isomers comprising s-cis and s-trans conformers of the carotenoid. The shorter fluorescence lifetime is associated with an s-cis carotenoid conformer where the close approach between the donor and acceptor moieties provides through-space electronic coupling in addition to the through-bond component.

Growth morphology and spectroscopy of multiwall carbon nanotubes synthesized by pyrolysis of iron phthalocyanine

Carbon nanotubes (CNTs) were synthesized by Chemical Vapor Deposition (CVD) from the pyrolytic decomposition of Iron Phthalocyanine (FePc) molecules, on SiO2/Si(111) substrates in the presence of a hydrogen flow. FePc molecules contribute simultaneously both to the formation of the precursor Fe nanoparticles and also as a Carbon source. Different experimental conditions were examined. Samples were characterized by scanning electron microscopy, transmission electron microscopy, Raman spectroscopy, X-ray photoelectron spectroscopy, and inverse photoemission. The resulting samples are highly oriented multiwall carbon nanotubes films, with heights in the range between: 4 and 20 microm. The tubes diameter is strongly dependent on growth temperature. Our experimental results show evidence of a transition in the growth mechanism, from a tip growth to a base growth mode, as the decomposition temperature is increased. Preliminary spectroscopic measurements performed on these MWCNTs, show the unoccupied density of states has several resonances close to Fermi level, related both to the graphene electronic structure and the formation of the tube.

Polyion complex micelles for photodynamic therapy: Incorporation of dendritic photosensitizer excitable at long wavelength relevant to improved tissue-penetrating property

A polymeric micelle (DPcZn/m) system, which is formed via an electrostatic interaction of anionic dendrimer phthalocyanine (DPcZn) and poly(ethylene glycol)-poly(l-lysine) block copolymers (PEG-b-PLL), was prepared for use as an effective photosensitizer for photodynamic therapy. DPcZn/m exhibited strong Q band absorption around 650 nm, a useful wavelength for high tissue penetration. Dynamic light scattering studies indicated that the DPcZn/m system has a relevant size of 50 nm for intravenous administration. Under light irradiation, either DPcZn or DPcZn/m exhibited efficient consumption of dissolved oxygen in a medium to generate reactive oxygen species and an irradiation-time-dependent increase in photocytotoxicity. The photodynamic efficacy of the DPcZn was drastically improved by the incorporation into the polymeric micelles, typically exhibiting more than two orders of magnitude higher photocytotoxicity compared with the free DPcZn at 60-min photoirradiation.

Efficient microwave enhanced regioselective synthesis of a series of benzimidazolyl/triazolyl spiro [indole-thiazolidinones] as potent antifungal agents and crystal structure of spiro[3H-indole-3,2′-thiazolidine]-3′(1,2,4-triazol-3-yl)-2,4′(1H)-dione

A microwave-assisted three-component, regioselective one-pot cyclocondensation method has been developed for the synthesis of a series of novel spiro[indole-thiazolidinones] (6a-l) using an environmentally benign procedure at atmospheric pressure in open vessel. This rapid method produces pure products in high yields within few minutes in comparison to a conventional two-step procedure. The crystal structure of one representative compound has been determined by X-ray diffraction. The synthesized compounds have been screened 'in vitro' for antifungal activity against Rhizoctonia solani, Fusarium oxysporum and Collectotrichum capsici. All compounds have shown good activity against these pathogens.

An efficient and practical synthesis of bis(indolyl)methanes catalyzed by aminosulfonic acid under ultrasound

Synthesis of bis(indolyl)methanes via electrophilic substitution reactions of indoles with aromatic aldehydes and ketones catalyzed by aminosulfonic acid was carried out in 23-96% yield at 30-38 degrees C in EtOH aqueous solution under ultrasound irradiation.

Intracellular photodynamic therapy with photosensitizer-nanoparticle conjugates: cancer therapy using a ‘Trojan horse’

Phthalocyanine-nanoparticle conjugates have been designed and synthesised for the delivery of hydrophobic photosensitizers for photodynamic therapy (PDT) of cancer. The phthalocyanine photosensitizer stabilized gold nanoparticles have an average diameter of 2-4 nm. The synthetic strategy interdigitates a phase transfer reagent between phthalocyanine molecules on the particle surface that solubilises the hydrophobic photosensitizer in polar solvents enabling delivery of the nanoparticle conjugates to cells. The phthalocyanine is present in the monomeric form on the nanoparticle surface, absorbs radiation maximally at 695 nm and catalytically produces the cytotoxic species singlet oxygen with high efficiency. These properties suggest that the phthalocyanine-nanoparticle conjugates are ideally suited for PDT. In a process that can be considered as cancer therapy using a 'Trojan horse', when the nanoparticle conjugates are incubated with HeLa cells (a cervical cancer cell line), they are taken up thus delivering the phthalocyanine photosensitizer directly into the cell interior. Irradiation of the nanoparticle conjugates within the HeLa cells induced substantial cell mortality through the photodynamic production of singlet oxygen. The PDT efficiency of the nanoparticle conjugates, determined using colorimetric assay, was twice that obtained using the free phthalocyanine derivative. Following PDT with the nanoparticle conjugates, morphological changes to the HeLa cellular structure were indicative of cell mortality via apoptosis. Further evidence of apoptosis was provided through the bioluminescent assay detection of caspase 3/7. Our results suggest that gold nanoparticle conjugates are an excellent vehicle for the delivery of surface bound hydrophobic photosensitizers for efficacious photodynamic therapy of cultured tumour cells.

High resolution photofragment translational spectroscopy of the near UV photolysis of indole: Dissociation via the1πσ* state

The fragmentation dynamics of indole molecules following excitation at 193.3 nm, and at a number of different wavelengths in the range 240 < or = lambda(phot) < or = 286 nm, have been investigated by H Rydberg atom photofragment translational spectroscopy. The longer wavelength measurements have been complemented by measurements of excitation spectra for forming parent and fragment ions by two (or more) photon ionisation processes. Analysis identifies at least three distinct contributions to the observed H atom yield, two of which are attributable to dissociation of indole following radiationless transfer from the 1pi pi* excited states (traditionally labelled 1L(b) and 1L(a)) prepared by UV single photon absorption. The structured channel evident in total kinetic energy release (TKER) spectra recorded at lambda(phot) < or = 263 nm is rationalised in terms of N-H bond fission following initial pi* <-- pi excitation and subsequent coupling to the 1pi sigma* potential energy surface via a conical intersection between the respective surfaces--thereby validating recent theoretical predictions regarding the importance of this process (Sobolewski et al., Phys. Chem. Chem. Phys., 2002, 4, 1093). Analysis provides an upper limit for the N-H bond strength in indole: D0(H-indolyl) < or = 31,900 cm(-1). Unimolecular decay of highly vibrationally excited ground state molecules formed by internal conversion from the initially prepared 1pi pi* states is a source of (slow) H atoms but their contribution to the TKER spectra measured in the present work is dwarfed by that from H atoms generated by one or more (unintended but unavoidable) multiphoton processes.

A novel10B-enriched carboranyl-containing phthalocyanine as a radio- and photo-sensitising agent for boron neutron capture therapy and photodynamic therapy of tumours: in vitro and in vivo studies

The synthesis of a Zn(ii)-phthalocyanine derivative bearing four 10B-enriched o-carboranyl units (10B-ZnB4Pc) and its natural isotopic abundance analogue (ZnB4Pc) in the peripheral positions of the tetraazaisoindole macrocycle is presented. The photophysical properties of ZnB4Pc, as tested against model biological systems, were found to be similar with those typical of other photodynamically active porphyrin-type photosensitisers, including a singlet oxygen quantum yield of 0.67. The carboranyl-carrying phthalocyanine was efficiently accumulated by B16F1 melanotic melanoma cells in vitro, appeared to be partitioned in at least some subcellular organelles and, upon red light irradiation, induced extensive cell mortality. Moreover, ZnB4Pc, once i.v.-injected to C57BL/6 mice bearing a subcutaneously transplanted pigmented melanoma, photosensitised an important tumour response, provided that the irradiation at 600-700 nm was performed 3 h after the phthalocyanine administration, when appreciable concentrations of ZnB4Pc were still present in the serum. Analogously, irradiation of the 10B-ZnB4Pc-loaded pigmented melanoma with thermal neutrons 24 h after injection led to a 4 day delay in tumour growth as compared with control untreated mice. These results open the possibility to use one chemical compound as both a photosensitising and a radiosensitising agent for the treatment of tumours by the combined application of photodynamic therapy and boron neutron capture therapy.

Floral fluorescence effect

The way flowers appear to insects is crucial for pollination. Here we describe an internal light-filtering effect in the flowers of Mirabilis jalapa, in which the visible fluorescence emitted by one pigment, a yellow betaxanthin, is absorbed by another, a violet betacyanin, to create a contrasting fluorescent pattern on the flower's petals. This finding opens up new possibilities for pollinator perception as fluorescence has not previously been considered as a potential signal in flowers.

Tuning Photoinduced Energy- and Electron-Transfer Events in Subphthalocyanine-Phthalocyanine Dyads

A series of subphthalocyanine-phthalocyanine dyads has been prepared by means of palladium-catalyzed cross-coupling reactions between a monoalkynylphthalocyanine and different monoiodosubphthalocyanines. Electronic coupling between the two photoactive units is ensured by a rigid and pi-conjugated alkynyl spacer. In addition, the electronic characteristics of the subphthalocyanine moiety were modulated by the introduction of different peripheral substituents. Cyclic and Osteryoung square-wave voltammetry experiments revealed that the reduction potential of this subunit can be decreased by about 400 mV on going from thioether or no substituents to nitro groups. As a consequence, the energy level of the charge-transfer state could be fine-tuned so as to gain control over the fate of the photoexcitation energy in each subunit. The diverse steady-state and time-resolved photophysical techniques employed demonstrated that, when the charge-transfer state lies high in energy, a quantitative singlet-singlet energy-transfer mechanism from the excited subphthalocyanine to the phthalocyanine takes place. On the contrary, stabilization of the radical pair by lowering the redox gap between electron donor and acceptor results in a highly efficient photoinduced electron-transfer process, even in solvents of low polarity such as toluene (Phi(ET) approximately 0.9). These features, together with the extraordinary absorptive cross section that these molecular ensembles display across the whole UV/Vis spectrum, make them model candidates for application in situations where broadband light sources are needed.