Lattice distortion of CaF2 nanocrystals for shortening their 19F longitude relaxation time.

As a promising 19F MRI tracer, the relatively slow lattice-spin relaxation of CaF2 nanocrystals leads to an unacceptable scanning time in MR imaging, hampering their application. We herein controlled the size and lattice distortion of CaF2 nanocrystals and showed that the shortened interplanar spacing pronouncedly sped up the longitude relaxation.

Improvement in storage quality of postharvest tomato fruits by nitroxyl liposomes treatment.

Nitroxyl (HNO) has attracted much attention due to its unique biological activity. To investigate the preservation effect of HNO on fruits, a nitroxyl liposome based on 1-nitrosocyclohexyl acetate was prepared and characterized by infrared spectroscopy and transmission electron microscopy. The optimal preparation conditions were explored, and then HNO liposomes were prepared under the optimal conditions to study the effect of HNO liposomes on postharvest quality of tomatoes. The tomato fruits were treated with different concentrations (0, 5, 10, 15 and 20 µmol L-1) of HNO liposomes and stored at room temperature. The results indicated that treatment with HNO liposomes can more effectively delay the browning and slow down the decrease in lightness of tomatoes. Additionally, HNO liposomes can reduce the activity of PPO and POD, inhibit the increase of MDA and total phenol content. These results suggest that treatment with HNO liposomes can effectively preserve the quality of tomatoes.

Revisiting the factors influencing the magnetic resonance contrast of Gd2O3 nanoparticles.

Gadolinium oxide nanoparticles (GONs) have the potential to be one of the best candidates for the contrast agents of magnetic resonance imaging. Even though the influence of parameters on the relaxation has been substantially demonstrated, the variation of the r 1 of GONs with a similar structure and surface chemistry implied our limited understanding. We herein synthesized GONs with adjustable size, shape, and crystallinity, modified them with a series of molecules with different acidities, and recorded their r 1 values and imaging contrast. Our results showed that the isoelectric point could be regarded as an indicator of the relaxation covering the influence of both surface modification and size, which highlighted the impact of protons dissociated from the contrast agents. We further showed that the nanoparticles with lower crystallinity possess higher relaxivity, and this phenomenon manifested significantly under a low field. Our work clarified that the longitudinal relaxivity of Gd2O3 nanoparticles is sensitively dependent on the numbers of H+ generated from the surface and in the environment, which may shed light on developing high-performance nanoparticulate T 1 contrast agents.

Fixed-diameter upconversion nanorods with controllable length and their interaction with cells.

A series of NaYF4: Yb, Er upconversion nanorods with fixed diameter and controllable length were synthesized by the injection of sodium trifluoroacetate (CF3COONa) mixed with potassium trifluoroacetate (CF3COOK) precursor into a heated solution of ligand. We found that with the increased percentage of CF3COOK, the length of resultant nanorods was increased from ∼40 nm to ∼200 nm whilst the diameter was kept in a narrow range of 37-42 nm. The elongation of nanorods was attributed to the specific absorption of sodium oleate on the prismatic facets, and the integration of potassium ions into the lattice as well. We further found that the elongated length affected the relative fluorescence intensity between red and green emission. More importantly, with fixed diameter, the cellular uptake of nanorods was found decreasing with the increase of their length. Meanwhile the decrease of diameter resulted in an increased cellular uptake. These results were attributed to both specific surface area and possibly varied contacting angle between nanorods and cell membrane. The current work not only suggested a synthetic method for the precise control of upconversion nanorods, but also shed light on the design of nanocrystals for cell-related biomedical applications.

Multimodal Nanoprobe Based on Upconversion Nanoparticles for Monitoring Implanted Stem Cells in Bone Defect of Big Animal.

Monitoring implanted stem cells in bone regeneration and other cell therapies is of great importance to reveal the mechanism of tissue repair and to optimize clinical treatments. However, big challenge still remained in lacking an imaging nanoprobe. Herein, we designed surface modified upconversion nanoparticles (UCNs) with multimodal imaging capabilities of fluorescence, magnetic resonance imaging (MRI) and dual-energy computed tomography (CT). It was found that the UCNs can label stem cells in an efficient (over 200 pg/cell) and long-term (at least 14 days) manner, with almost no influence on the viability, cell cycle, apoptosis, and multilineage differentiation. Thus, clinical dual-energy CT and MRI were successfully applied to observe the migration of labeled cells on a bone-defect model of rabbit for at least 14 days. The results visualized the gathering of stem cells at the defect site of cortical bone, and the in vivo images were well-correlated with the in vitro fluorescence observation without extra staining. Therefore, a potentially translatable nanoprobe was developed for noninvasive and real-time tracking of cells, which may be meaningful for understanding the bone regeneration in clinic and shed light on the visualization of cells in other cell therapies.

Interleukin-17-induced expression of monocyte chemoattractant protein-1 in cardiac myocytes requires nuclear factor κB through the phosphorylation of p65.

IL-17 plays a key role in a variety of autoimmune diseases. MCP-1 is involved in the infiltration of mononuclear cells of myocardium in VMC. However, the relationship between IL-17 and MCP-1 in myocardial injury remains unclear. In this study, expression of MCP-1 mRNA and protein in cardiac myocytes was detected with qRT-PCR and ELISA, respectively. It was found that IL-17A induced MCP-1 expression in a dose- and time-dependent manner in cardiac myocytes, which could be blocked by IL-17A and IL-17RA neutralizing antibodies. NF-κB p65 and p-p65 protein expression in cardiac myocytes was studied with western blotting. Rates of p-p65 in whole lysates and in nuclear lysates all increased in the first 15 min. Meanwhile, the amount of NF-κB p65 in whole lysates did not change, but the amount of NF-κB p65 in nuclear lysates increased in the first 15 min. Then the optimal sequence and concentration of NF-κB p65 siRNAs was selected. After transfection of 10 nM siRNA-2 of NF-κB p65 into cardiac myocytes before stimulation by IL-17A, expression of MCP-1 mRNA and protein obviously decreased. In conclusion, expression of MCP-1 induced by IL-17 requires NF-κB through the phosphorylation of p65 in cardiac myocytes, which is meaningful to study the onset of chronic viral myocarditis and will provide a new target for the treatment of viral myocarditis.

[Effect of IL-17 on the expression of monocyte chemoattractant protein-1 in the cardiac myocytes].

AIM: To investigate the effect of interleukin-17 (IL-17) on the expression of monocyte chemoattractant protein-1(MCP-1) in the primary cultured cardiac myocytes. METHODS: The cardiac myocytes were isolated from neonatal mice by different adhesion method. The expressions of IL-17R and MCP-1 in the cardiac myocytes were evaluated by reverse transcription-polymerase chain reaction (RT-PCR). And the concentration of MCP-1 in the culture supernatant of the cardiac myocytes was detected by enzyme-linked immunosorbent assay (ELISA). RESULTS: There was the expression of IL-17R in the cardiac myocytes. After stimulated by IL-17, the expressions of MCP-1 in the cardiac myocytes were significantly increased in dose-dependent manner compared with that of culture medium control (P<0.05). The amount of MCP-1 mRNA in the cardiac myocytes was the highest at 4 h after stimulated by IL-17. And then the amount of MCP-1 mRNA in the cardiac myocytes began to descend. The concentrations of MCP-1 in the culture supernatant of the cardiac myocytes increased in time-dependent manner and had significant differences with the control group (P<0.05). CONCLUSION: The cardiac myocytes could express IL-17R. IL-17 could up-regulate the expression of MCP-1 in the cardiac myocytes, which was associated with the dose and stimulation time of IL-17.