Radio frequency plasma assisted surface modification of Fe3O4 nanoparticles using polyaniline/polypyrrole for bioimaging and magnetic hyperthermia applications.

Surface modification of superparamagnetic Fe3O4 nanoparticles using polymers (polyaniline/polypyrrole) was done by radio frequency (r.f.) plasma polymerization technique and characterized by XRD, TEM, TG/DTA and VSM. Surface-passivated Fe3O4 nanoparticles with polymers were having spherical/rod-shaped structures with superparamagnetic properties. Broad visible photoluminescence emission bands were observed at 445 and 580 nm for polyaniline-coated Fe3O4 and at 488 nm for polypyrrole-coated Fe3O4. These samples exhibit good fluorescence emissions with L929 cellular assay and were non-toxic. Magnetic hyperthermia response of Fe3O4 and polymer (polyaniline/polypyrrole)-coated Fe3O4 was evaluated and all the samples exhibit hyperthermia activity in the range of 42-45 °C. Specific loss power (SLP) values of polyaniline and polypyrrole-coated Fe3O4 nanoparticles (5 and 10 mg/ml) exhibit a controlled heat generation with an increase in the magnetic field.

NIR-Triggered Blasting Nanovesicles for Targeted Multimodal Image-Guided Synergistic Cancer Photothermal and Chemotherapy.

Escorting therapeutics for malignancies by nano-encapsulation to ameliorate treatment effects and mitigate side effects has been pursued in precision medicine. However, the majority of drug delivery systems suffer from uncontrollable drug release kinetics and thus lead to unsatisfactory triggered-release efficiency along with severe side effects. Herein, we developed a unique nanovesicle delivery system that shows near-infrared (NIR) light-triggered drug release behavior and minimal premature drug release. By co-encapsulation of superparamagnetic iron oxide (SPIO) nanoparticles, the ultrasound contrast agent perfluorohexane (PFH), and cisplatin in a silicate-polyaniline vesicle, we achieved the controllable release of cisplatin in a thermal-responsive manner. Specifically, vaporization of PFH triggered by the heat generated from NIR irradiation imparts high inner vesicle pressure on the nanovesicles, leading to pressure-induced nanovesicle collapse and subsequent cisplatin release. Moreover, the multimodal imaging capability can track tumor engagement of the nanovesicles and assess their therapeutic effects. Due to its precise inherent NIR-triggered drug release, our system shows excellent tumor eradication efficacy and biocompatibility in vivo, empowering it with great prospects for future clinical translation.

Polyaniline@Au organic-inorganic nanohybrids with thermometer readout for photothermal immunoassay of tumor marker.

A photothermal immunoassay using a thermometer as readout based on polyaniline@Au organic-inorganic nanohybrids was built. Temperature output is acquired due to the photothermal effect of the photothermal nanomaterial. Polyaniline@Au organic-inorganic nanohybrids were synthesized by interfacial reactions with high photothermal conversion efficiency. A sandwich structure of the immunocomplex was prepared on a microplate for determination of carcinoembryonic antigen (CEA) by polyaniline@Au organic-inorganic nanohybrids as nanolabel. The released heat based on light-to-heat conversion from the photothermal nanolabel under NIR irradiation is detectable using the thermometer. The increased temperature is directly proportional to CEA concentration. The linear range of the photothermal immunoassay is 0.20 to 25 ng mL-1 with determination limit of 0.17 ng mL-1. Polyaniline@Au organic-inorganic nanohybrids with high photothermal conversion efficiency was synthesized as labels to construct photothermal immunosensor. The sandwich-type immunoassay was built on 96 hole plate based on specific binding of antigen and antibody. Carcinoembryonic antigen in sample was detected quantitatively by thermometer readout.

Acceptor Engineering for Optimized ROS Generation Facilitates Reprogramming Macrophages to M1 Phenotype in Photodynamic Immunotherapy.

Reprogramming tumor-associated macrophages to an antitumor M1 phenotype by photodynamic therapy is a promising strategy to overcome the immunosuppression of tumor microenvironment for boosted immunotherapy. However, it remains unclear how the reactive oxygen species (ROS) generated from type I and II mechanisms, relate to the macrophage polarization efficacy. Herein, we design and synthesize three donor-acceptor structured photosensitizers with varied ROS-generating efficiencies. Surprisingly, we discovered that the extracellular ROS generated from type I mechanism are mainly responsible for reprogramming the macrophages from a pro-tumor type (M2) to an anti-tumor state (M1). In vivo experiments prove that the photosensitizer can trigger photodynamic immunotherapy for effective suppression of the tumor growth, while the therapeutic outcome is abolished with depleted macrophages. Overall, our strategy highlights the designing guideline of macrophage-activatable photosensitizers.

In Vivo Bioimaging and Photodynamic Therapy Based on Two-Photon Fluorescent Conjugated Polymers Containing Dibenzothiophene-S,S-dioxide Derivatives.

As a critical component for photodynamic therapy toward cancer treatment, photosensitizers require high photoinduced reactive oxygen species generation efficiency, good biocompatibility, and high phototoxicity. Herein, a series of donor-acceptor conjugated polymers containing dibenzothiophene-S,S-dioxide derivatives are designed and synthesized, which can be used as effective photosensitizers. The resulting copolymer PTA5 shows strong green light emission with high photoluminescence quantum yields owing to the intercrossed excited state of local existed and charge transfer states. The PTA5 nanoparticles can be fabricated by encapsulation with a biocompatible polymer matrix. Upon excitation at 800 nm, these nanoparticles present a relatively large two-photon absorption cross section of 3.29 × 106 GM. These nanoparticles also exhibit good photostability in water and thus can be utilized for bioimaging. The tissue-penetrating depths of up to 170 µm for hepatic vessels and 380 µm for blood vessels of mouse ear were achieved using PTA5 nanoparticles. Furthermore, PTA5 nanoparticles show impressive reactive oxygen species generation capability under the irradiation of a white light source. This can be attributed to the effective intersystem crossing between high-level excited state. Upon irradiation with white light (400-700 nm) at 50 mW cm-2 for 5 min every other day, the tumor growth can be effectively suppressed in the presence of PTA5 nanoparticles. These findings demonstrate that PTA5 nanoparticles can be used as a photosensitizer for photodynamic therapy.

ACQ-to-AIE Transformation: Tuning Molecular Packing by Regioisomerization for Two-Photon NIR Bioimaging.

The traditional design strategies for highly bright solid-state luminescent materials rely on weakening the intermolecular π-π interactions, which may limit diversity when developing new materials. Herein, we propose a strategy of tuning the molecular packing mode by regioisomerization to regulate the solid-state fluorescence. TBP-e-TPA with a molecular rotor in the end position of a planar core adopts a long-range cofacial packing mode, which in the solid state is almost non-emissive. By shifting molecular rotors to the bay position, the resultant TBP-b-TPA possesses a discrete cross packing mode, giving a quantum yield of 15.6±0.2 %. These results demonstrate the relationship between the solid-state fluorescence efficiency and the molecule's packing mode. Thanks to the good photophysical properties, TBP-b-TPA nanoparticles were used for two-photon deep brain imaging. This molecular design philosophy provides a new way of designing highly bright solid-state fluorophores.

Polypyrrole and polyaniline nanocomposites with high photothermal conversion efficiency.

The simple and scalable synthesis of poly[2-(methacryloyloxy)ethyl phosphorylcholine] (PMPC)-coated conducting polymer (CP) nanocomposites is described. These functional nanocomposites exhibit tunable absorption in the near-infrared region with relatively high photothermal efficiencies. More importantly, their potential for bio-imaging and therapeutic treatment is proven by cellular uptake and cytotoxicity studies.

Aggregation-Dependent Photoreactive Hemicyanine Assembly as a Photobactericide.

Organic materials that show substantial reactivity under visible light have received considerable attention due to their wide applications in chemical and biological systems. Hemicyanine pigments possess a strong intramolecular donor-acceptor structure and thereby display intense absorption in the visible spectral region. However, most excitons are consumed via the twisted intramolecular charge-transfer (TICT) process, making hemicyanines generally inert to light. Herein, we describe the development of an amphiphilic hemicyanine dye whose aggregation could be easily regulated using salt or counterions. More importantly, its intrinsic photoreactivity was successfully induced by steric restriction and cofacial arrangement within the H-aggregate, thus creating an effective photobactericide. This strategy could be extended to the development of photocatalysts for photosynthesis and a photosensitizer for photodynamic therapy.

Proton Nuclear Magnetic Resonance Spectroscopy Analysis of Mixtures of Chlorhexidine with Different Oxidizing Agents Activated by Photon-Induced Photoacoustic Streaming for Root Canal Irrigation.

Objective: The aim of this in vitro study was to investigate the possible interactions between photon-induced photoacoustic streaming (PIPS™)-activated oxidizing agents and 2% chlorhexidine digluconate. Background data: There is no information about the safety of laser-activated oxidizing agents in combination usage with chlorhexidine gluconate. Materials and methods: Groups were designed as follows G1: 98% para-chloroaniline (PCA); G2: 2% chlorhexidine (CHX); G3: 5.25% sodium hypochlorite (NaOCl) +2% CHX; G4: 5.25% NaOCl (30 sec PIPS activated) +2% CHX; G5: 5.25% NaOCl (60 sec PIPS activated) +2% CHX; G6: 3.5% chlorine dioxide (ClO2) + 2% CHX; G7: 3.5% (ClO2) (30 sec PIPS activated) +2% CHX; G8: 3.5% (ClO2) (60 sec PIPS activated) +2% CHX. The laser-irrigation protocol was performed with an erbium:yttrium-aluminum-garnet laser with a wavelength of 2940 nm equipped with a 140 mm long endodontic fiber tip (PIPS) using 10 mJ at 15 Hz (0.15 W), per pulse operating outputs. Groups were analyzed with proton nuclear magnetic resonance spectroscopy, using PCA as an internal standard. Results: No free PCA was formed in any groups of mixtures or after PIPS activation. Conclusions: Mixing of 3.5% ClO2 and 2% CHX does not form bulky precipitates, unlike the mixture NaOCl + CHX. PIPS activation does not cause changes in reactions of oxidizing agents.

Radical polymerization inside living cells.

Polymerization reactions conducted inside cells must be compatible with the complex intracellular environment, which contains numerous molecules and functional groups that could potentially prevent or quench polymerization reactions. Here we report a strategy for directly synthesizing unnatural polymers in cells through free radical photopolymerization using a number of biocompatible acrylic and methacrylic monomers. This offers a platform to manipulate, track and control cellular behaviour by the in cellulo generation of macromolecules that have the ability to alter cellular motility, label cells by the generation of fluorescent polymers for long-term tracking studies, as well as generate a variety of nanostructures within cells. It is remarkable that free radical polymerization chemistry can take place within such complex cellular environments. This demonstration opens up a multitude of new possibilities for how chemists can modulate cellular function and behaviour and for understanding cellular behaviour in response to the generation of free radicals.

Excellent Temperature-Control Based on Reversible Thermochromic Materials for Light-Driven Phase Change Materials System.

Light-driven phase change materials (PCMs) have received significant attention due to their capacity to convert visible light into thermal energy, storing it as latent heat. However, continuous photo-thermal conversion can cause the PCMs to reach high thermal equilibrium temperatures after phase transition. In our study, a novel light-driven phase change material system with temperature-control properties was constructed using a thermochromic compound. Thermochromic phase change materials (TC-PCMs) were prepared by introducing 2-anilino-6-dibutylamino-3-methylfluoran (ODB-2) and bisphenol A (BPA) into 1-hexadecanol (1-HD) in various proportions. Photo-thermal conversion performance was investigated with solar radiation (low power of 0.09 W/cm2) and a xenon lamp (at a high power of 0.14 W/cm2). The TC-PCMs showed a low equilibrium temperature due to variations in absorbance. Specifically, the temperature of TC-PCM180 (ODB-2, bisphenol A and 1-HD ratio 1:2:180) could stabilize at 54 °C approximately. TC-PCMs exhibited reversibility and repeatability after 20 irradiation and cooling cycles.

Instantaneous Detection of Trichlorinated Carbon via Photo-Induced Electron Transfer toward Chemosensor for Toxic Organochlorides.

Despite the usefulness of organochlorides as raw materials for organic synthesis, they cause several issues in the human body, such as hepatic dysfunction, tumor, and heavy damage to the central nervous system. Especially when organochlorides contain three or more chlorinated carbons, they tend to be more toxic to the human body possibly owing to relatively high reactivity. Several electron donors (TPCAs) are designed to devise a novel detection system for toxic organochlorides containing trichlorinated carbons, and the detection mechanism of the devised sensor system is systematically identified by EPR measurement and the analysis of the solution after the detection of chloroform, which is used as a model compound. Since the detection system simultaneously utilizes the radical-generation capability and the low LUMO level of the trichlorinated carbon, it provides high selectivity against most of the common organic compounds including other organochlorides containing mono- or dichlorinated carbons, and the outstanding selectivity of the designed sensor has been verified with Mirex composed of numerous chlorinated carbons. In addition, the detection system exhibits immediate sensing capability because only electron transfer and radical reaction are involved in the detection process. Finally, when diphosgene is detected with the devised sensing platform, a noticeable change in fluorescence intensities can be identified within 5 s even for a diphosgene concentration of less than 1 ppm.

Enhanced photocatalytic removal of Safranin-T dye under sunlight within minute time intervals using heulandite/polyaniline@ nickel oxide composite as a novel photocatalyst.

Natural zeolite heulandite/polyaniline composite (Hu/PANI) was synthesized for the first time as catalyst support for nickel oxide photocatalyst (Hu/PANI@Ni2O3). The structural, chemical, morphological, textural and optical properties were investigated using different techniques. The synthetic Ni2O3 crystals showed well developed flaky habits with diameter range 200-400 nm and length range 1-4 µm. The estimated band gap energies of Hu/PANI composite and Hu/PANI@Ni2O3 composite are 1.8 eV and 1.46 eV, respectively, which are remarkably smaller than the recorded value for pure nickel oxide. The photocatalytic properties of Hu/PANI@Ni2O3 composite for efficient degradation of safranin-T dye were evaluated under sunlight as a function of irradiation time, initial dye concentration, catalyst mass, solution pH, and the catalyst stability. Hu/PANI@Ni2O3 composite exhibits amazing photocatalytic degradation efficiency for safranin dye, whereas 80%, 98%, and ~ 100% of 5 mg/l dye were removed after only 1 min of solar irradiation using 0.025, 0.03, and 0.035 g of Hu/PANI@Ni2O3, respectively. The higher concentrations of the dye (10-50 mg/L) can be fully removed within minutes by increasing the solution pH or using higher doses from the Hu/PANI@Ni2O3 catalyst. The removal percentage achieved the maximum value at the alkaline conditions. Also, the Hu/PANI@Ni2O3 displayed high stability and remain 84.5% of the initial photocatalytic efficiency after 5 runs. Additionally, the composite can be used effectively in the removal of different types of dyes and mixed dyes within the same time intervals. Thus, loading of nickel oxide onto hybrid Hu/PANI composite as a catalyst support achieved amazing photocatalytic degradation capacity.

Tuning the Hydrophobicity of a Mitochondria-Targeted NO Photodonor.

A few compounds in which the nitric oxide (NO) photodonor N-[4-nitro-3-(trifluoromethyl)phenyl]propane-1,3-diamine is joined to the mitochondria-targeting alkyltriphenylphosphonium moiety via flexible spacers of variable length were synthesized. The lipophilicity of the products was evaluated by measuring their partition coefficients in n-octanol/water. The obtained values, markedly lower than those calculated, are consistent with the likely collapsed conformation assumed by the compounds in solution, as suggested by molecular dynamics simulations. The capacity of the compounds to release NO under visible light irradiation was evaluated by measuring nitrite production by means of the Griess reaction. The accumulation of compounds in the mitochondria of human lung adenocarcinoma A549 cells was assessed by UPLC-MS. Interestingly, compound 13 [(9-((3-((4-nitro-3-(trifluoromethyl)phenyl)amino)propyl)amino)-9-oxononyl) triphenylphosphonium bromide] displayed both the highest accumulation value and high toxicity toward A549 cells upon irradiation-mediated NO release in mitochondria.

Visual Evoked Potential Recovery by Subretinal Implantation of Photoelectric Dye-Coupled Thin Film Retinal Prosthesis in Monkey Eyes With Macular Degeneration.

Retinal prosthesis or artificial retina is a promising modality of treatment for outer retinal degeneration, caused by primary and secondary loss of photoreceptor cells, in hereditary retinal dystrophy and age-related macular degeneration, respectively. Okayama University-type retinal prosthesis (OUReP) is a photoelectric dye-coupled polyethylene film which generates electric potential in response to light and stimulates nearby neurons. The dye-coupled films were implanted by vitreous surgery in the subretinal space of monkey eyes with macular degeneration which had been induced by cobalt chloride injection from the scleral side. A pilot 1-month observation study involved 6 monkeys and a pivotal 6-month observation study involved 8 monkeys. Of 8 monkeys in 6-month group, 3 monkeys underwent dye-coupled film removal at 5 months and were observed further for 1 month. The amplitude of visual evoked potential which had been reduced by macular degeneration did recover at 1 month after film implantation and maintained the level at 6 months. Optical coherence tomography showed no retinal detachment, and full-field electroretinograms maintained a-wave and b-wave amplitudes, indicative of no retinal toxicity. Pathological examinations after 6-month implantation showed structural integrity of the inner retinal layer in close apposition to dye-coupled films. The implanted films which were removed by vitrectomy 5 months later showed light-evoked surface electric potentials by scanning Kelvin probe measurement. The photoelectric dye-coupled film (OUReP), which serves as a light-receiver and a displacement current generator in the subretinal space of the eye, has a potential for recovering vision in diseases with photoreceptor cell loss, such as retinitis pigmentosa and age-related macular degeneration.

Aniline chlorination by in situ formed Ag-Cl complexes under simulated solar light irradiation.

Ag speciation in a chloride medium was dependent upon the Cl/Ag ratio after releasing into surface water. In this study, the photoreaction of in situ formed Ag-Cl species and their effects on aniline photochlorination were systematically investigated. Our results suggested that formation of chloroaniline was strongly relevant to the Cl/Ag ratio and could be interpreted using the thermodynamically expected speciation of Ag in the presence of Cl-. AgCl was the main species responsible for the photochlorination of aniline. Both photoinduced hole and •OH drove the oxidation of Cl- to radical •Cl, which promoted the chlorination of aniline. Ag0 formation was observed from the surface plasmon resonance absorption during AgCl photoreaction. This study revealed that Ag+ released into Cl--containing water may result in the formation of chlorinated intermediates of organic compounds under solar light irradiation.

Removal of oxalic acid, oxamic acid and aniline by a combined photolysis and ozonation process.

Aniline (ANL), an aromatic amine, oxalic acid (OXA) and oxamic acid (OMA), short-chain carboxylic acids, were chosen as model organic pollutants for testing the combined effect of neat photolysis and ozonation in the treatment of aqueous effluents. In order to better understand the results, single ozonation and neat photolysis were also carried out. OXA has a high refractory character relatively to single ozonation and neat photolysis only accounted for 26% conversion of OXA after 2 h of reaction. On the other hand, OXA complete degradation was observed in less than an hour when ozone and light were used simultaneously. Despite OMA, a compound never studied before by a combined ozonation and photolysis treatment, being highly refractory to oxidation, more than 50% was removed by photo-ozonation after 3 h of reaction. In the case of ANL, both single ozonation and photo-ozonation resulted in 100% removal in a short reaction period due to the high reactivity of ozone to attack this type of molecules; however, only the combined method leads to efficient mineralization (89%) after 3 h of reaction. A significant synergetic effect was observed in the degradation of the selected contaminants by the simultaneous use of ozone and light, since the mineralization rate of combined method is higher than the sum of the mineralization rates of the individual treatments. The promising results observed in the degradation of the selected contaminants are paving the way to the application of photo-ozonation in the treatment of wastewater containing this type of pollutants.

Highly efficient exciplex formation via radical ion pair recombination in X-irradiated alkane solutions for luminophores with short fluorescence lifetimes.

X-irradiation of alkane solutions of N,N-dimethylaniline with various organic luminophores produces characteristic emission bands ascribed to the corresponding exciplexes. In contrast to optical generation, which requires diffusion-controlled quenching of excited states, an additional channel of exciplex formation via irreversible recombination of radical ion pairs is operative here, which produces exciplexes in solution with high efficiency even for p-terphenyl and diphenylacetylene having fluorescence decay times of 0.95 ns and 8 ps, respectively. The exciplex emission band is sensitive to an external magnetic field and exerts a very large observed magnetic field effect of up to 20%, the maximum possible value under the conditions of the described experiment.

Synthesis and characterization of CoFe2O4/polyaniline nanocomposites for electromagnetic interference applications.

The Cobalt ferrite (CoFe2O4) powders were synthesized by Co-precipitation method. The as prepared ferrite powders were incorporated into a polyaniline matrix at various volumetric ratios. The as prepared composites of ferrite and polyaniline powders were characterized using X-ray diffraction (XRD), transmission electron microscope (TEM). The particle size of CoFe2O4 is found to be 20 nm. The saturation magnetization (M(s)) of all the composites was found to be decreasing with decrease of ferrite content, while coercivity (H(c)) remained at the value corresponding to pure cobalt ferrite nanopowders. The complex permittivity (epsilon' and epsilon") and permeability (mu' and mu") of composite samples were measured in the range of 1 MHz to 1.1 GHz. The value of epsilon' and mu' found to be increased with ferrite volume concentration.

Diaryl-substituted ortho-carboranes as a new class of hypoxia inducible factor-1α inhibitors.

Diaryl-substituted ortho-carboranes 1 were synthesized from the corresponding alkynes by decaborane coupling under microwave-irradiated conditions with a combination of N,N-dimethylaniline and chlorobenzene. Among the compounds synthesized, 1a and 1d exhibited significant inhibition of hypoxia-induced HIF-1 transcriptional activity. Both compounds similarly suppressed hypoxia-induced HIF-1α accumulation in a concentration-dependent manner without affecting HIF-1α mRNA expression.