Objective To manufacture magnetic microbubbles with dual-response to ultrasound and magnetic fields.Methods Microbubbles of ultrasound contrast agent (ST68) based on a surfactant were prepared by the acoustic cavitation method.Fe3O4 magnetic nanoparticles with negative charge were synthesized using the polyol procedure.Magnetic microbubbles were generated by depositing polyethylenimine and Fe3O4 magnetic nanoparticles alternately onto the microbubbles using the layer-by-layer self-assembly.In vitro ultrasonography was performed on a silicone tube with/without magnetic microbubbles (3 × 108/ml) by a self-made device to observe the movement of magnetic microbubbles under the effects of magnetic field.In vivo imaging was performed on the kidney of New Zealand rabbits before and after the injection of magnetic microbubbles.Results The Fe3O4 nanoparticles carried a stable negative charge of (-24.6 ± 6.7) mV and more than 98％ of the particles were less than 8 μm in diameter,meeting the size requirement of an ultrasound contrast agent for intravenous administration.There was no echoic signal in the silicone tube before injection of magnetic microbubbles,but there were strong echoic signals after injection.After applying a magnetic field,the magnetic microbubbles moved along the direction of the magnetic flux.In vivo ultrasound imaging could not visualize the kidney before injection of magnetic microbubbles,but could remarkably visualize the kidney after injection.Conclusions The magnetic microbubbles exhibit favorable magnetic targeting and ultrasound contrast enhancement characteristics.Such properties may serve as the foundation to study their potential for simultaneous diagnosis and treatment in the future.

Objective To fabricate an ultrasound/fluorescence bi-modal contrast agent by encapsulating fluorescent quantum dots into polymeric ultrasound contrast agent microbubbles.Methods Polylactic acid (PLA,500 mg),(1R)-(+)-camphor (50 mg) and CdSe/ZnS quantum dots (0.5 ml,2.3 μmol/L)were dissolved or dispersed in dichloromethane (10 ml) to form in an organic phase.Ammonium carbonate solution and poly (vinyl alcohol) solution were employed as the internal and external water phase,respectively.The fluorescent microbubbles were generated using double emulsion solvent evaporation and lyophilization methods.The morphology and illumination were characterized by scanning electron microscopy (SEM) and fluorescence spectrophotometry.Synchronized contrast-enhanced ultrasound and fluorescence imaging was acquired by injecting fluorescent microbubbles into the silicone tube coupled to a self-made ultrasound/fluorescence imaging device.Ultrasound/fluorescence bi-modal in vivo imaging was acquired on the kidney of New Zealand rabbits and suckling mice.Results The fluorescent microbubbles were hollow spheres with an averaged diameter of (1.62 ± 1.47) μm.More than 99％ of these microbubbles were less than 8 μm in diameter,which meeted the size criteria for ultrasound contrast agents.The fluorescence emission peak of the microbubbles appeared at 632 nm,indicating that good luminescence properties of quantum dots were maintained.In vitro ultrasound/fluorescence imaging showed no echoic signal when the silicone tube was filled with saline,but there was a strong echo when filled with fluorescent microbubbles.The liquid column with fluorescent microbubbles emitted red luminescence under ultraviolet irradiation.The kidney of the rabbit was remarkably enhanced after the administration of fluorescent microbubbles.Bright fluorescence could be observed at the injection site of the suckling mice via subcutaneous injection.Conclusions A bi-modal but single contrast agent based on polymeric microbubbles has been successfully fabricated for the use of ultrasound and fluorescence imaging.It retains the good characteristics of both echogenicity and fluorescence,which complement each other in case of limitations imposed by uni-modal,single agents.

Objective:To study the effect of resveratrol (RES) on interleukin-1β (IL-1β)-induced chondrocytes and its pathways of action.Methods:Wistar mammary rat chondrocytes were extracted and divided into 5 groups: control group, IL-1β group, RES+IL-1β group, RES+IL-1β+EX-527 [silent information regulator 1 (SIRT1) inhibitor] group and RES+IL-1β+AS [frame transcription factor O1 (FOXO1) inhibitor] group. Quantitative real time polymerase chain reaction (qRT-PCR) was used to detect SIRT1, forkhead FOXO1 and matrix metalloproteinase 3 (MMP-3) mRNA expression. Protein expression of chondrocyte type Ⅱ collagen (Col-Ⅱ) detected by immunofluorescence, and the expression of chondrocyte SIRT1 and p-FOXO1/FOXO1 was measured by Western blot. The expression of chondrocyte inflammatory factors IL-6 and TNF-α was measured by enzyme-linked immunosorbent assay. One-way analysis of variance (ANOVA) was performed and two-way comparisons between groups were made using the least significant difference (LSD) method. P< 0.001 was statistically significant. Results:Compared to normal chondrocytes, the mRNA and protein expressions of Col-Ⅱ, SIRT1, FOXO1 and p-FOXO1/FOXO1 in chondrocytes induced by IL-1β was significantly decreased ( P<0.001). The secretion of tumor necrosis factor (TNF)-α [(24.70±2.84), t=19.24, P<0.001] and IL-6 [(3.35±0.28), t=12.97, P<0.001] was significantly increased, and the mRNA expression of MMP-3 [(2.46± 0.23), t=12.61, P<0.001] was significantly increased. The mRNA and protein expressions of Col-Ⅱ, SIRT1, FOXO1 and p-FOXO1/FOXO1 were significantly increased. The secretion of TNF-α [(12.60±1.05), t=10.14, P<0.001] and IL-6 [(2.00±0.15), t=9.89, P<0.001] was significantly reduced by RES treated IL-1β-induced chondrocytes. mRNA expression of MMP-3 [(1.30±0.14), t=10.460, P<0.001] was decreased. After adding SIRT1 inhibitor EX-527 or FOXO1 inhibitor AS, RES significantly reduced the mRNA and protein expression of Col-Ⅱ, SIRT1, FOXO1 and p-FOXO1/FOXO1 in IL-1β-induced chondrocytes ( P<0.001). The secretion of TNFα and IL-6 was significantly decreased ( P<0.001), and the mRNA expression of MMP-3 was significantly decreased ( P<0.001). Conclusion:RES significantly ameliorates IL-1β-induced cartilage extracellular matrix egradation and inflammatory responses via the SIRT1/FOXO1 pathway.