Spin Exchange Interaction in Substituted Copper Phthalocyanine Crystalline Thin Films

All rights reserved. The origins of spin exchange in crystalline thin films of Copper Octabutoxy Phthalocyanine (Cu-OBPc) are investigated using Magnetic Circular Dichroism (MCD) spectroscopy. These studies are made possible by a solution deposition technique which produces highly ordered films with macroscopic grain sizes suitable for optical studies. For temperatures lower than 2K, the contribution of a specific state in the valence band manifold originating from the hybridized lone pair in nitrogen orbitals of the Phthalocyanine ring, bears the Brillouin-like signature of an exchange interaction with the localized d-shell Cu spins. A comprehensive MCD spectral analysis coupled with a molecular field model of a σπ-d exchange analogous to sp-d interactions in Diluted Magnetic Semiconductors (DMS) renders an enhanced Zeeman splitting and a modified g-factor of -4 for the electrons that mediate the interaction. These studies define an experimental tool for identifying electronic states involved in spin-dependent exchange interactions in organic materials

Spatially, Temporally and Polarization-Resolved Photoluminescence Exploration of Excitons in Crystalline Phthalocyanine Thin Films

The lack of long range order in organic semiconductor thin films prevents the unveiling of the complete nature of excitons in optical experiments, because the diffraction limited beam diameters in the bandgap region far exceed typical crystalline grain sizes. Here we present spatially-, temporally- and polarization-resolved dual photoluminescence/linear dichroism microscopy experiments that investigate exciton states within a single crystalline grain in solution-processed phthalocyanine thin films. These experiments reveal the existence of a delocalized singlet exciton, polarized along the high mobility axis in this quasi-1D electronic system. The strong delocalized {\pi} orbitals overlap controlled by the molecular stacking along the high mobility axis is responsible for breaking the radiative recombination selection rules. Using our linear dichroism scanning microscopy setup we further established a rotation of molecules (i.e. a structural phase transition) that occurs above 100 K prevents the observation of this exciton at room temperature.Comment: submitted to Journal of Chem Phys letter

Cassava foliage affects the microbial diversity of Chinese indigenous geese caecum using 16S rRNA sequencing

Geese are extremely adept in utilizing plant-derived roughage within their diet. However, the intestinal microbiome of geese remains limited, especially the dietary effect on microbial diversity. Cassava foliage was widely used in animal feed, but little information is available for geese. In this study, the geese were fed with control diet (CK), experimental diet supplemented with 5% cassava foliage (CF5) or 10% (CF10) for 42 days, respectively. The cecal samples were collected after animals were killed. High-Throughput sequencing technology was used to investigate the microbial diversity in the caecum of geese with different dietary supplements. Taxonomic analysis indicated that the predominant phyla were distinct with different dietary treatments. The phyla Firmicutes (51.4%), Bacteroidetes (29.55%) and Proteobacteria (7.90%) were dominant in the CK group, but Bacteroidetes (65.19% and 67.29%,) Firmicutes (18.01% and 17.39%), Proteobacteria (8.72% and 10.18%), Synergistete (2.51% and 1.76%) and Spirochaetes (2.60% and 1.46%) were dominant in CF5 and CF10 groups. The abundance of Firmicutes was negatively correlated with the supplementation of cassava foliage. However, the abundance of Bacteroidetes and Proteobacteria were positively correlated with the supplementation of cassava foliage. Our study also revealed that the microbial communities were significantly different at genus levels. Genes related to nutrient and energy metabolism, immunity and signal transduction pathways were primarily enriched by the microbiome

Design and Application of Near-Infrared Nanomaterial-Liposome Hybrid Nanocarriers for Cancer Photothermal Therapy

Liposomes are attractive carriers for targeted and controlled drug delivery receiving increasing attention in cancer photothermal therapy. However, the field of creating near-infrared nanomaterial-liposome hybrid nanocarriers (NIRN-Lips) is relatively little understood. The hybrid nanocarriers combine the dual superiority of nanomaterials and liposomes, with more stable particles, enhanced photoluminescence, higher tumor permeability, better tumor-targeted drug delivery, stimulus-responsive drug release, and thus exhibiting better anti-tumor efficacy. Herein, this review covers the liposomes supported various types of near-infrared nanomaterials, including gold-based nanomaterials, carbon-based nanomaterials, and semiconductor quantum dots. Specifically, the NIRN-Lips are described in terms of their feature, synthesis, and drug-release mechanism. The design considerations of NIRN-Lips are highlighted. Further, we briefly introduced the photothermal conversion mechanism of NIRNs and the cell death mechanism induced by photothermal therapy. Subsequently, we provided a brief conclusion of NIRNs-Lips applied in cancer photothermal therapy. Finally, we discussed a synopsis of associated challenges and future perspectives for the applications of NIRN-Lips in cancer photothermal therapy

Supercritical fluid coating of flavonoids on excipients enhances drug release and antioxidant activity

Supercritical anti-solvent fluidized bed (SAS-FB) technology can be applied to reduce particle size, prevent particle aggregation, and improve the dissolution and bioavailability of poorly soluble drugs. In this work, drug-loaded microparticles of three similar structures, the flavonoids luteolin (LUT), naringenin (NGR), and dihydromyricetin (DMY) were prepared using SAS-FB technology, to explore its effect on the coating of flavonoid particles. Operating temperature, pressure, carrier, solvent, and concentration of drug solution were investigated for their effects on the yield and dissolution of flavonoid particles. The results showed that temperature, pressure, carrier, and drug solution concentration have a large effect on yield. Within the study range, low supercritical CO2 density at higher temperature and lower pressure, a larger surface area carrier, and moderate drug solution concentration led to a higher yield. The effect of the solvent on the yield of flavonoids is a result of multiple factors. Scanning electron microscopy (SEM) images showed that the drug-loaded particles prepared from different carriers and solvents have different precipitations pattern on the carrier surface, and their particle sizes were smaller than unprocessed particles and those prepared by the SAS process. Fluorescence microscopy (FM) results showed that the flavonoids were uniformly coated on the carrier. X-ray powder diffraction (XRPD) results showed that the crystalline morphology of SAS-FB particles remained unchanged after the SAS-FB process, although the diffraction peak intensity decreased. The cumulative dissolution of SAS-FB particles was more than four times faster in the first 5 min than that of the unprocessed flavonoids. The antioxidant activity of SAS-FB processed LUT, NGR and DMY was 1.89-3.78 times, 4.92-10.68 times and 0.99-2.57 times higher than that of the untreated flavonoids, respectively. The approach provides a reference for the application of SAS-FB technology in flavonoids

Macroscopic Molecular Ordering and Exciton Delocalization in Crystalline Phthalocyanine Thin Films

We present spatially-, temporally- and polarization-resolved dual photoluminescence/linear dichroism microscopy experiments that investigate the correlation between long-range order and the nature of exciton states in solution-processed phthalocyanine thin films. The influence of grain boundaries and disorder is absent in these films because typical grain sizes are 3 orders of magnitude larger than focused excitation beam diameters. These experiments reveal the existence of a delocalized singlet exciton, polarized along the high mobility axis in this quasi-1D electronic system. The strong delocalized π orbitals overlap, controlled by the molecular stacking along the high mobility axis, is responsible for breaking the radiative recombination selection rules. Using our linear dichroism scanning microscopy setup, we further established that a rotation of molecules (i.e., a structural phase transition) that occurs above 100 K prevents the observation of this exciton at room temperature