pH-Activatable Cyanine Dyes for Selective Tumor Imaging Using Near-Infrared Fluorescence and Photoacoustic Modalities

Photoacoustic (PA) imaging is an emerging molecular imaging modality that complements fluorescence imaging and enables high resolution within deep tissue. Fluorescence/PA multimodality imaging would be a powerful technique to extract more comprehensive information from targets than traditional single-modality imaging. In this paper, we developed a new pH-activatable sensor, CypHRGD, which is applicable to both fluorescence and PA detection. CypHRGD was derived from our previous near-infrared pH-sensing platform, in which substitution with a bulky phenyl group and functionalization with a cRGD peptide remarkably improved the sensor's biocompatibility with attenuated dye aggregation. The multi-modality imaging applications of CypHRGD were demonstrated in cultured cells and cancer-xenografted mice with rapid kinetics and high sensitivity and specificity, which relies on cRGD-facilitated tumor targeting, probe accumulation and subsequent activation in the acidic organelles after endocytosis

Amphiphilic γ-cyclodextrin–fullerene complexes with photodynamic activity

Amphiphilic γ-cyclodextrin–fullerene 2 : 1 complexes (CLFCH complexes) were prepared by high-speed vibration milling of lipophilic tail-grafted γ-cyclodextrin (γ-CD), hydrophilic tail-grafted γ-CD and fullerene C₆₀. The transamidation of γ-CD–fullerene complexes having two amino groups with lipophilic and hydrophilic activated esters also afforded amphiphilic CLFCH complexes. Self-assemblies consisting of amphiphilic CLFCH complexes efficiently generated singlet oxygen under photoirradiation. Under visible light irradiation conditions, CLFCH complexes bearing a vitamin E moiety as a lipophilic tail showed high photodynamic activity toward cancer cells

Photoacoustic signal enhancement of Al- and Si-Phthalocyanines caused by photoinduced cleavage of water-soluble axial ligand

Aluminum and silicon phthalocyanines bearing water-soluble poly(ethylene glycol) as axial ligands which formed vesicles in water enhanced photoacoustic (PA) signal intensities under continuous photoirradiation. The photoinduced cleavage of axial ligands in water-soluble phthalocyanines is a key step to produce phthalocyanine aggregates which generate strong photoacoustic wave

Atom locations in a Ni doped η-(Cu,Ni)6Sn5 intermetallic compound

The present study has succeeded in direct determination of the location of dopant Ni atoms in η-(Cu,Ni)Sn by aberration-corrected scanning transmission electron microscopy (STEM) including atomic-resolution imaging as well as elemental mapping by X-ray energy-dispersive spectroscopy (XEDS). The three sublattices of Sn, Cu1 and Cu2 were distinguished in atomic-resolution images observed along the [21¯1¯0] direction. Atomic-resolution XEDS maps have verified for the first time that the dopant Ni atoms located at the Cu2 sites in η-(Cu,Ni)Sn, taking advantage of the Poisson non-local principal component analysis (NLPCA) processing and the lattice-averaging procedure

MMP-2-Activatable Photoacoustic Tumor Imaging Probes Based on Al- and Si-Naphthalocyanines

Enzyme-activatable photoacoustic probes are powerful contrast agents to visualize diseases in which a specific enzyme is overexpressed. In this study, aluminum and silicon naphthalocyanines (AlNc and SiNc, respectively) conjugated with matrix metalloprotease-2 (MMP-2)-responsive PLGLAG peptide sequence and poly(ethylene glycol) (PEG) as an axial ligand were designed and synthesized. AlNc-peptide-PEG conjugates AlNc-pep-PEG formed dimeric species interacting with each other through face-to-face H-aggregation in water, while SiNc-based conjugates SiNc-pep-PEG hardly interacted with each other because of the two bulky hydrophilic axial ligands. Both conjugates formed spherical nanometer-sized self-assemblies in water, generating photoacoustic waves under near-infrared photoirradiation. The treatment of MNc-peptide-PEG conjugates (M = Al, Si) with MMP-2 smoothly induced the cleavage of the PLGLAG sequence to release the hydrophilic PEG moiety, resulting in the aggregation of MNcs. By comparing the PA signal intensity changes at 680 and 760 nm, the photoacoustic signal intensity ratios were shown to be enhanced by 3–5 times after incubation with MMP-2. We demonstrated that MNc-peptide-PEG conjugates (M = Al, Si) could work as activatable photoacoustic probes in the in vitro experiment of MMP-2-overexpressed cell line HT-1080 as well as the in vivo photoacoustic imaging of HT-1080-bearing mice

The effects of trace Sb and Zn additions on Cu6Sn5 lithium-ion battery anodes

Sn-based compounds are promising candidates for application as anodes in lithium-ion batteries (LIBs) due to the favourable storage capacity of Sn at 993 mAh g(-1) compared to carbon at 372 mAh g(-1). The use of Sn-based anodes also avoids some of the safety concerns associated with carbon anodes. However, the large volume changes during lithiation and delithiation of pure Sn anodes often results in poor cyclic performance. Alloying Sn with Cu, an element inactive with respect to Li, buffers the expansion stresses and can improve cycling performance. Cu6Sn5 is therefore a promising candidate anode material. In this work, the effects of Sb and Zn additions on the morphology, crystal structure, atomic arrangements and the electrochemical performance of the anodes were evaluated. Characterisation with synchrotron X-ray powder diffraction and C-s-corrected transmission electron microscopy revealed the larger lattice parameters, higher symmetry crystal structures and well-ordered atomic arrangements in the Sb and Zn modified electrodes, which resulted in a more than 50% increase in cycling capacity from 490 mAh g(-1) to 760 mAh g(-1)

In-situ investigation of the hydrogen release mechanism in bulk Mg2NiH4

Hydrogen storage is an important aspect to enable the so-called hydrogen economy. Mg-Ni alloys are among the most promising candidates for solid-state hydrogen storage systems yet many questions remain unanswered regarding the hydriding/dehydriding mechanism of the alloys. MgNiH particularly has received much attention both for its potential as a hydrogen storage medium and also exhibits interesting properties relating to its different polymorphs. Here, the dehydriding mechanism in bulk MgNiH is investigated using in-situ ultra-high voltage transmission electron microscopy (TEM) combined with Synchrotron powder X-ray diffraction (XRPD) and differential scanning calorimetry (DSC). We find that the hydrogen release is based on a mechanism of nucleation and growth of MgNiH (x∼0–0.3) solid solution grains and is greatly enhanced in the presence of crystal defects occurring as a result of the polymorphic phase transformation. Also importantly, with atomic resolution TEM imaging a high density of stacking faults is identified in the dehydrided MgNiH (x∼0–0.3) lattices