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Review Article Issue
A mini-review on rare-earth down-conversion nanoparticles for NIR-II imaging of biological systems
Nano Research 2020, 13 (5): 1281-1294
Published: 25 March 2020
Downloads:30

Rare-earth (RE) based luminescent probes exhibit rich optical properties including upconversion and down-conversion luminescence spanning a broad spectral range from 300 to 3,000 nm, and have generated great scientific and practical interest from telecommunication to biological imaging. While upconversion nanoparticles have been investigated for decades, down-conversion luminescence of RE-based probes in the second near-infrared (NIR-II, 1,000-1,700 nm) window for in vivo biological imaging with sub-centimeter tissue penetration and micrometer image resolution has come into light only recently. In this review, we present recent progress on RE-based NIR-II probes for in vivo vasculature and molecular imaging with a focus on Er3+-based nanoparticles due to the down-conversion luminescence at the long-wavelength end of the NIR-II window (NIR-IIb, 1,500-1,700 nm). Imaging in NIR-IIb is superior to imaging with organic probes such as ICG and IRDye800 in the ~ 800 nm NIR range and the 1,000-1,300 nm short end of NIR-II range, owing to minimized light scattering and autofluorescence background. Doping by cerium and other ions and phase engineering of Er3+-based nanoparticles, combined with surface hydrophilic coating optimization can afford ultrabright, biocompatible NIR-IIb probe towards clinical translation for human use. The Nd3+-based probes with NIR-II emission at 1,050 and 1,330 nm are also discussed, including Nd3+ doped nanocrystals and Nd3+-organic ligand complexes. This review also points out future directions for further development of multi-functional RE NIR-II probes for biological imaging.

Research Article Issue
An electrodeposition approach to metal/metal oxide heterostructures for active hydrogen evolution catalysts in near-neutral electrolytes
Nano Research 2019, 12 (6): 1431-1435
Published: 29 May 2019
Downloads:25

Neutral water splitting is attractive for its use of non-corrosive and environmentally friendly electrolytes. However, catalyst development for hydrogen and oxygen evolution remains a challenge under neutral conditions. Here we report a simple electrodeposition and reductive annealing procedure to produce a highly active Ni-Co-Cr metal/metal oxide heterostructured catalyst directly on Ni foam. The resulting electrocatalyst for hydrogen evolution reaction (HER) requires only 198 mV of overpotential to reach 100 mA/cm2 in 1 M potassium phosphate (pH = 7.4) and can operate for at least two days without significant performance decay. Scanning transmission electron microscopy coupled with electron energy loss spectroscopy (STEM-EELS) imaging reveals a Ni-Co alloy core decorated with blended oxides layers of NiO, CoO and Cr2O3. The metal/metal oxide interfaces are suggested to be responsible for the high HER activity.

Open Access Editorial Issue
The inaugural Nano Research Young Innovators (NR45) Award in nanobiotechnology
Nano Research 2018, 11 (10): 4931-4935
Published: 03 October 2018
Downloads:39

Research Article Issue
A theranostic agent for cancer therapy and imaging in the second nearinfrared window
Nano Research 2019, 12 (2): 273-279
Published: 29 September 2018
Downloads:16

Theranostic nanoparticles are integrated systems useful for simultaneous diagnosis and imaging guided delivery of therapeutic drugs, with wide ranging potential applications in the clinic. Here we developed a theranostic nanoparticle (~ 24 nm size by dynamic light scattering) p-FE-PTX-FA based on polymeric micelle encapsulating an organic dye (FE) fluorescing in the 1, 000–1, 700 nm second near-infrared (NIR-II) window and an anti-cancer drug paclitaxel. Folic acid (FA) was conjugated to the nanoparticles to afford specific binding to molecular folate receptors on murine breast cancer 4T1 tumor cells. In vivo, the nanoparticles accumulated in 4T1 tumor through both passive and active targeting effect. Under an 808 nm laser excitation, fluorescence detection above 1, 300 nm afforded a large Stokes shift, allowing targeted molecular imaging tumor with high signal to background ratios, reaching a high tumor to normal tissue signal ratio (T/NT) of (20.0 ± 2.3). Further, 4T1 tumors on mice were completed eradicated by paclitaxel released from p-FE-PTA-FA within 20 days of the first injection. Pharmacokinetics and histology studies indicated p-FE-PTX-FA had no obvious toxic side effects to major organs. This represented the first NIR-II theranostic agent developed.

Research Article Issue
Nickel-coated silicon photocathode for water splitting in alkaline electrolytes
Nano Research 2015, 8 (5): 1577-1583
Published: 17 January 2015
Downloads:17

Photoelectrochemical (PEC) water splitting is a promising approach to harvest and store solar energy [1]. Silicon has been widely investigated for PEC photoelectrodes due to its suitable band gap (1.12 eV) matching the solar spectrum [2]. Here we investigate employing nickel both as a catalyst and protecting layer of a p-type silicon photocathode for photoelectrochemical hydrogen evolution in basic electrolytes for the first time. The silicon photocathode was made by depositing 15 nm Ti on a p-type silicon wafer followed by 5 nm Ni. The photocathode afforded an onset potential of ~0.3 V vs. the reversible hydrogen electrode (RHE) in alkaline solution (1 M KOH). The stability of the Ni/Ti/p-Si photocathode showed a 100 mV decay over 12 h in KOH, but the stability was significantly improved when the photocathode was operated in potassium borate buffer solution (pH ≈ 9.5). The electrode surface was found to remain intact after 12 h of continuous operation at a constant current density of 10 mA/cm2 in potassium borate buffer, suggesting that Ni affords good protection of Si based photocathodes in borate buffers.

Research Article Issue
WS2 nanoflakes from nanotubes for electrocatalysis
Nano Research 2013, 6 (12): 921-928
Published: 12 October 2013
Downloads:20

Next-generation catalysts for water splitting are crucial towards a renewable hydrogen economy. MoS2 and WS2 represent earth-abundant, noble metal cathode alternatives with high catalytic activity at edge sites. One challenge in their development is to nanostructure these materials in order to achieve increased performance through the creation of additional edge sites. In this work, we demonstrate a simple route to form nanostructured-WS2 using sonochemical exfoliation to break interlayer and intralayer bonds in WS2 nanotubes. The resulting few-layer nanoflakes are ~100 nm wide with a high density of edge sites. WS2 nanoflakes are utilized as cathodes for the hydrogen evolution reaction (HER) and exhibit superior performance to WS2 nanotubes and bulk particles, with a lower onset potential, shallower Tafel slope and increased current density. Future work may employ ultra-small nanoflakes, dopant atoms, or graphene hybrids to further improve electrocatalytic activity.

Research Article Issue
Short Channel Field-Effect Transistors from Highly Enriched Semiconducting Carbon Nanotubes
Nano Research 2012, 5 (6): 388-394
Published: 06 May 2012
Downloads:27

Semiconducting single-walled carbon nanotubes (s-SWNTs) with a purity of ~98% have been obtained by gel filtration of arc-discharge grown SWNTs with diameters in the range 1.2–1.6 nm. Multi-laser Raman spectroscopy confirmed the presence of less than 2% of metallic SWNTs (m-SWNTs) in the s-SWNT enriched sample. Measurement of ~50 individual tubes in Pd-contacted devices with channel length 200 nm showed on/off ratios of > 104, conductances of 1.38–5.8 μS, and mobilities in the range 40–150 cm2/(V·s). Short channel multi-tube devices with ~100 tubes showed lower on/off ratios due to residual m-SWNTs, although the on-current was greatly increased relative to the devices made from individual tubes.

Research Article Issue
Multifunctional FeCo–Graphitic Carbon Nanocrystals for Combined Imaging, Drug Delivery and Tumor-Specific Photothermal Therapy in Mice
Nano Research 2011, 4 (12): 1248-1260
Published: 04 November 2011
Downloads:12

Ultrasmall FeCo–graphitic carbon shell nanocrystals (FeCo/GC) are promising multifunctional materials capable of highly efficient drug delivery in vitro and magnetic resonance imaging in vivo. In this work, we demonstrate the use of FeCo/GC for highly effective cancer therapy through combined drug delivery, tumor-selective near-infrared photothermal therapy, and cancer imaging of a 4T1 syngeneic breast cancer model. The graphitic carbon shell of the ~4 nm FeCo/GC readily loads doxorubicin (DOX) via π–π stacking and absorbs near-infrared light giving photothermal heating. When used for cancer treatment, intravenously administrated FeCo/GC–DOX led to complete tumor regression in 45% of mice when combined with 20 min of near-infrared laser irradiation selectively heating the tumor to 43–45 ℃. In addition, the use of FeCo/GC–DOX results in reduced systemic toxicity compared with free DOX and appears to be safe in mice monitored for over 1 yr. FeCo/GC–DOX is shown to be a highly integrated nanoparticle system for synergistic cancer therapy leading to tumor regression of a highly aggressive tumor model.

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