High-efficiency hydrocracking of phenanthrene into BTX aromatics over a Ni-modified lamellar-crystal HY zeolite.

A new Ni-HY zeolite with lamellar-crystals was prepared as a catalyst for phenanthrene hydrocracking. It showed significantly improved reactivity and BTX (benzene, toluene and xylene) selectivity (up to 99.1% and 75.6%, respectively), depending on a reasonable synergistic effect between its excellent internal-diffusion and the high-efficiency concerted catalysis of surface metal-Ni active sites and acid sites. In particular, compared with a conventional Ni-HY with diamond-shaped crystals, its significantly shortened diffusion-reaction path of the micropore system in the lamellar crystals greatly enhanced the diffusion-reaction efficiency of large-molecule phenanthrene and polycyclic intermediates and remarkably improved the utilization of both pores and internal reactive sites, powerfully promoting phenanthrene into benzene series conversion. The much decreased diffusion-residence time of benzene-series products in shortened channels also effectively weakened the further cracking loss of the benzene-ring, leading to enhanced BTX selectivity. Moreover, this shorter-channel Ni-HY catalyst with a higher external surface area and mesoporous volume also exhibited greatly improved catalytic stability attributed to its stronger capabilities of accommodating coke and resisting coke-deposition. The phenanthrene conversion of >76.3% and the BTX yield of >46.3% were obtained during a 60 h on-stream reaction.

Fiber endface photoacoustic generator for quantitative photoacoustic tomography.

We demonstrate a novel fiber endface photoacoustic (PA) generator using infrared (IR) 144 laser dye dispersed within an ultraviolet adhesive. The generator provides a wide acoustic bandwidth in the transducer frequency range of 2-7 MHz, high thermal conversion efficiency (${\gt}90\%$), good PA signal controllability (well-controlled IR 144 concentration), and high feasibility (simple procedures). Through a series of experimental validations, we show that this fiber-based endface PA generator can be a useful tool for a broad range of biomedical applications such as calibrating the local absorption coefficient of biological tissue for quantitative PA tomography.

Augmenting insect olfaction performance through nano-neuromodulation.

Biological olfactory systems are highly sensitive and selective, often outperforming engineered chemical sensors in highly complex and dynamic environments. As a result, there is much interest in using biological systems to build sensors. However, approaches to read-out information from biological systems, especially neural signals, tend to be suboptimal due to the number of electrodes that can be used and where these can be placed. Here we aim to overcome this suboptimality in neural information read-out by using a nano-enabled neuromodulation strategy to augment insect olfaction-based chemical sensors. By harnessing the photothermal properties of nanostructures and releasing a select neuromodulator on demand, we show that the odour-evoked response from the interrogated regions of the insect olfactory system can not only be enhanced but can also improve odour identification.

Gold nanoparticle-enhanced X-ray microtomography of the rodent reveals region-specific cerebrospinal fluid circulation in the brain.

Cerebrospinal fluid (CSF) is essential for the development and function of the central nervous system (CNS). However, the brain and its interstitium have largely been thought of as a single entity through which CSF circulates, and it is not known whether specific cell populations within the CNS preferentially interact with the CSF. Here, we develop a technique for CSF tracking, gold nanoparticle-enhanced X-ray microtomography, to achieve micrometer-scale resolution visualization of CSF circulation patterns during development. Using this method and subsequent histological analysis in rodents, we identify previously uncharacterized CSF pathways from the subarachnoid space (particularly the basal cisterns) that mediate CSF-parenchymal interactions involving 24 functional-anatomic cell groupings in the brain and spinal cord. CSF distribution to these areas is largely restricted to early development and is altered in posthemorrhagic hydrocephalus. Our study also presents particle size-dependent CSF circulation patterns through the CNS including interaction between neurons and small CSF tracers, but not large CSF tracers. These findings have implications for understanding the biological basis of normal brain development and the pathogenesis of a broad range of disease states, including hydrocephalus.

Analysis of Stable Chelate-free Gadolinium Loaded Titanium Dioxide Nanoparticles for MRI-Guided Radionuclide Stimulated Cancer Treatment.

Background: Recent studies demonstrate that titanium dioxide nanoparticles (TiO2 NPs) are an effective source of reactive oxygen species (ROS) for photodynamic therapy and radionuclide stimulated dynamic therapy (RaST). Unfortunately tracking the in vivo distribution of TiO2 NPs noninvasively remains elusive. Objective: Given the use of gadolinium (Gd) chelates as effective contrast agents for magnetic resonance imaging (MRI), this study aims to (1) develop hybrid TiO2-Gd NPs that exhibit high relaxivity for tracking the NPs without loss of ROS generating capacity; and (2) establish a simple colorimetric assay for quantifying Gd loading and stability. Methods: A chelate-free, heat-induced method was used to load Gd onto TiO2 NPs, which was coated with transferrin (Tf). A sensitive colorimetric assay and inductively coupled plasma mass spectrometry (ICP-MS) were used to determine Gd loading and stability of the TiO2-Gd-Tf NPs. Measurement of the relaxivity was performed on a 1.4 T relaxometer and a 4.7 T small animal magnetic resonance scanner to estimate the effects of magnetic field strength. ROS was quantified by activated dichlorodihydrofluorescein diacetate fluorescence. Cell uptake of the NPs and RaST were monitored by fluorescence microscopy. Both 3 T and 4.7 T scanners were used to image the in vivo distribution of intravenously injected NPs in tumor-bearing mice. Results: A simple colorimetric assay accurately determined both the loading and stability of the NPs compared with the expensive and complex ICP-MS method. Coating of the TiO2-Gd NPs with Tf stabilized the nanoconstruct and minimized aggregation. The TiO2-Gd-Tf maintained ROS-generating capability without inducing cell death at a wide range of concentrations but induced significant cell death under RaST conditions in the presence of F-18 radiolabeled 2-fluorodeoxyglucose. The longitudinal (r1 = 10.43 mM-1s-1) and transverse (r2 = 13.43 mM-1s-1) relaxivity of TiO2-Gd-Tf NPs were about twice and thrice, respectively, those of clinically used Gd contrast agent (Gd-DTPA; r1 = 3.77 mM-1s-1 and r2 = 5.51 mM-1s-1) at 1.4 T. While the r1 (8.13 mM-1s-1) reduced to about twice that of Gd-DTPA (4.89 mM-1s-1) at 4.7 T, the corresponding r2 (87.15 mM-1s-1) increased by a factor 22.6 compared to Gd-DTPA (r2 = 3.85). MRI of tumor-bearing mice injected with TiO2-Gd-Tf NPs tracked the NPs distribution and accumulation in tumors. Conclusion: This work demonstrates that Arsenazo III colorimetric assay can substitute ICP-MS for determining the loading and stability of Gd-doped TiO2 NPs. The new nanoconstruct enabled RaST effect in cells, exhibited high relaxivity, and enhanced MRI contrast in tumors in vivo, paving the way for in vivo MRI-guided RaST.

Ultrathin surface coated water-soluble cobalt ferrite nanoparticles with high magnetic heating efficiency and rapid in vivo clearance.

To obtain magnetic nanoparticles with high magnetic heating efficiency and rapid in vivo clearance, this study utilized an improved linear response theory model to theoretically simulate the specific absorption rate (SAR) value versus the particle size of cobalt ferrite nanoparticles (CFNPs). An accurate SAR curve consistent with experimental results was obtained using cubes instead of spheres as the shape of CFNPs, given that cube was closer to the actual shape of prepared CFNPs. Under the guidance of simulation, we predicted and prepared water-soluble cubic CFNPs of 10-13 nm in size, with an ultrathin surface coating less than 1 nm in thickness. These CFNPs were experimentally verified to have high magnetic heating efficiency and rapid in vivo clearance rate. Our CFNPs of 11.8 nm in size had a high intrinsic loss power of 12.11 nHm2/kg. Most of the cells were killed within 30 min under magnetic heating with CFNPs. In an in vivo study, these CFNPs can heat a tumor area to 45 °C (ΔT > 9 °C) within 120 s under a weak alternating magnetic field (27 kA/m, 115 kHz). Notably, these CFNPs had significant tumor inhibition rate in vivo and can be cleared from the body by more than 64% within 2 weeks, demonstrating excellent rapid in vivo clearance. This result was close to the clearance level of the magnetic resonance imaging contrast agent Feridex. Therefore, our CFNPs had high magnetic heating efficiency and rapid in vivo clearance rate, indicating their great potential for future clinical applications.