Qun Tang

Synthesis of yttrium hydroxide and oxide nanotubes

Abstract Yttrium hydroxide nanotubes were hydrothermally synthesized via a metastable precursor, PEG–Y(NO 3 ) 3 complex. XRD patterns showed the product was a pure hexagonal phase of Y(OH) 3 . TEM images displayed that the nanotubes have outer diameters ranging from 80 to 200xa0nm, wall thicknesses of about 30xa0nm, and lengths up to several micrometers. The nanotube growth may have three stages: formation of a metastable PEG–Y(NO 3 ) 3 complex; nucleation and formation of Y(OH) 3 nanorods; developing Y(OH) 3 nanotubes. We proposed the Y(OH) 3 nanotubes growth mechanism to be a nucleation-diffusion growth based on the characterization results. Y 2 O 3 nanotubes were formed with smaller diameters after post-treatment at 500°C for 2xa0h.

A template-free aqueous route to ZnO nanorod arrays with high optical property

A mild template-free aqueous route was successfully established to synthesize well-aligned ZnO nanorod arrays, which were proved to exhibit high optical property by PL spectra.

A new type of silica-coated Gd2(CO3)3:Tb nanoparticle as a bifunctional agent for magnetic resonance imaging and fluorescent imaging

We report a new type of dual modal nanoprobe to combine optical and magnetic resonance bioimaging. A simple reverse microemulsion method and coating process was introduced to synthesize silica-coated Gd(2)(CO(3))(3):Tb nanoparticles, and the particles, with an average diameter of 16 nm, can be dispersed in water. As in vitro cell imaging of the nanoprobe shows, the nanoprobe accomplishes delivery to gastric SGC7901 cancer cells successfully in a short time, as well as NCI-H460 lung cancer cells. Furthermore, it presents no evidence of cell toxicity or adverse affect on kidney cell growth under high dose, which makes the nanoprobes optical bioimaging modality available. The possibility of using the nanoprobe for magnetic resonance imaging is also demonstrated, and the nanoprobe displays a clear T(1)-weighted effect and could potentially serve as a bimodal T(1)-positive contrast agent. Therefore, the new nanoprobe formed from carbonate nanoprobe doped with rare earth ions provides the dual modality of optical and magnetic resonance imaging.

Preparation, characterization and optical properties of terbium oxide nanotubes

Tb2O3 nanotubes were fabricated by calcination of the precursor Tb(OH)3 nanotubes prepared by a template-assisted hydrothermal route. The oxide nanotubes have outer diameters ranging from 80 to 100 nm, wall thickness of about 30 nm, and lengths up to several micrometers. The optical absorption spectrum shifted to high energy and became broad, more lines were observed in the emission bands in comparison with the bulk. Surface effects were found to account for these novel optical properties.

Development of PEGylated KMnF3 nanoparticles as a T1-weighted contrast agent: chemical synthesis, in vivo brain MR imaging, and accounting for high relaxivity.

Magnetic nanoparticles consisting of manganese-based T1-weighted contrast agents have rapidly achieved clinical application, however low proton relaxivity impedes further development. In this report, by analyzing nanoparticles surface oxidation states we propose the possible reason for the low r1 relaxivity of common MnO nanoparticles and develop PEGylated fluoroperovskite KMnF3 nanoparticles as new T1-weighted contrast agents, which exhibit the highest longitudinal relaxivity (r1 = 23.15 mM(-1) s(-1)) among all the reported manganese-based T1-weighted contrast agents. We, for the first time, illustrate a typical example showing that the surface oxidation states of metal ions exposed on the nanoparticles surfaces are able to influence not only the optical, magnetic, electronic or catalytic properties but also water proton longitudinal relaxivity when applied as an MRI contrast agent. Cytotoxicity tests demonstrate that the PEGylated KMnF3 nanoparticles are free from toxicity. Further in vivo MRI experiments distinctively depict fine anatomical features in brain imaging at a low dose of 5 mg of Mn per kg and possible removal from the kidneys due to their small size and biocompatibility.

Biocompatible KMnF3 nanoparticular contrast agent with proper plasma retention time for in vivo magnetic resonance imaging

Nanoparticular MRI contrast agents are rapidly becoming suitable for use in clinical diagnosis. An ideal nanoparticular contrast agent should be endowed with high relaxivity, biocompatibility, proper plasma retention time, and tissue-specific or tumor-targeting imaging. Herein we introduce PEGylated KMnF3 nanoparticles as a new type of T1 contrast agent. Studies showed that the nanoparticular contrast agent revealed high bio-stability with bovine serum albumin in PBS buffer solution, and presented excellent biocompatibility (low cytotoxicity, undetectable hemolysis and hemagglutination). Meanwhile the new contrast agent possessed proper plasma retention time (circulation half-life t1/2 is approximately 2xa0h) in the body of the administrated mice. It can be delivered into brain vessels and maintained there for hours, and is mostly cleared from the body within 48xa0h, as demonstrated by time-resolved MRI and Mn-biodistribution analysis. Those distinguishing features make it suitable to obtain contrast-enhanced brain magnetic resonance angiography. Moreover, through the process of passive targeting delivery, the T1 contrast agent clearly illuminates a brain tumor (glioma) with high contrast image and defined shape. This study demonstrates that PEGylated KMnF3 nanoparticles represent a promising biocompatible vascular contrast agent for magnetic resonance angiography and can potentially be further developed into an active targeted tumor MRI contrast agent.

Inorganic phosphate-triggered release of anti-cancer arsenic trioxide from a self-delivery system: An in vitro and in vivo study

On-demand drug delivery is becoming feasible via the design of either exogenous or endogenous stimulus-responsive drug delivery systems. Herein we report the development of gadolinium arsenite nanoparticles as a self-delivery platform to store, deliver and release arsenic trioxide (ATO, Trisenox), a clinical anti-cancer drug. Specifically, unloading of the small molecule drug is triggered by an endogenous stimulus: inorganic phosphate (Pi) in the blood, fluid, and soft or hard tissue. Kinetics in vitro demonstrated that ATO is released with high ON/OFF specificity and no leakage was observed in the silent state. The nanoparticles induced tumor cell apoptosis, and reduced cancer cell migration and invasion. Plasma pharmacokinetics verified extended retention time, but no obvious disturbance of phosphate balance. Therapeutic efficacy on a liver cancer xenograft mouse model was dramatically potentiated with reduced toxicity compared to the free drug. These results suggest a new drug delivery strategy which might be applied for ATO therapy on solid tumors.

Highly sensitive MRI contrast agent for enhanced visualization of tumors

Compared with other medical imaging techniques, magnetic resonance imaging (MRI) has an obvious disadvantage of low sensitivity, in other words, the injection dosage of the probe (contrast agent) is very high. In this paper, we developed c(RGDyK)-conjugated KMnF3 nanocubes as a tumor targeting T1 contrast agent. The short cyclic peptide (c(RGDyK)) was conjugated with carboxylic terminated KMnF3 nanoparticles via 1-ethyl-3-(3-dimethylaminopropyl)-carbodiimide (EDC) coupling. The nanoparticles have an appropriate hydrodynamic size and narrow size distribution. Furthermore, they showed high in vitro bio-stability and biocompatibility. Application of the c(RGDyK)-conjugated nanoparticles for in vivo MR imaging of tumors profoundly enhanced the image contrast to almost double. More importantly, the injection dosage required is one to two orders lower than that of a commercial or reported contrast agent. The c(RGDyK) short peptide was proven to play a targeting role, and c(RGDyK)-conjugated KMnF3 nanoparticles have a potential application for the diagnosis of tumors.

Non-degradable contrast agent with selective phagocytosis for cellular and hepatic magnetic resonance imaging

Degradation is the long-existing toxic issue of metal-containing inorganic medicine. In this paper, we fully investigated the degradation of dextran-coated KMnF3 nanocube in the in vitro and in vivo surroundings. Different from the general decomposing and ion releasing events, this special agent is resistant to acidic environment, as well as ion exchange. Non-degradability was proved by simulated and real cellular experiments. Moreover, it can be engulfed in the macrophage cells and kept stable in the lysosome. Due to its stability and highly selective phagocytosis, implanted liver cancer can be clearly visualized after administration.

The evaluation of lanthanum trapped prussian blue as a phosphate binding agent with reduced bone uptake

Toxicity arising from lanthanum accumulation in bone and liver is a big concern in the usage of lanthanum carbonate as a phosphate binder. In this paper colloidal lanthanum trapped Prussian blue is developed as a two-process-independent phosphate binder, which meets the requirement of separating two processes. The layered nanostructure of the as-formed LaPO4–PB hints its high binding affinity of phosphate and stability of lanthanum, hence free from absorption through the gastrointestinal tract, thus reducing lanthanum accumulation in the bone and liver is evidenced after long-term administration. Those results indicate that lanthanum trapped Prussian blue is a safe phosphate binder alternative to lanthanum carbonate.