Synthesis and anti-tumor activity study of water-soluble PEG-celastrol coupling derivatives as self-assembled nanoparticles.

To improve the drug-ability of celastrol, a series of PEGylation celastrol (PEGC) were designed and synthesized by conjugation with different kinds of polyethylene glycols (PEGs) with celastrol. Most of PEGCs could easily dissolve in water. In particular, one of them (DC1000) could be dispersed in water to form nanoparticles by self-assembly. The cytotoxic evaluation of PEGCs revealed that some of PEGCs showed more potent cytotoxicity than celastrol, and the molecular weight of PEG parts in PEGCs had apparent influence on their cytotoxic activity. Anti-tumor evaluation in vivo showed DC1000 had higher tumor inhibition rate and better safety than celastrol by intravenous administration with equivalent molar weight. These results revealed PEGylation might be an efficient and economical method to improve the water solubility and safety of celastrol and similar natural products.

Impact of microplastics on lead-contaminated riverine sediments: Based on the enzyme activities, DOM fractions, and bacterial community structure.

Microplastics (MPs) are able to interact with diverse contaminants in sediments. However, the impacts of MPs on sediment properties and bacterial community structure in heavy metal-contaminated sediments remain unclear. In this study, we investigated the adsorption of Pb(II) by sediment-MPs mixtures and the effects of different concentration MPs on sediment enzyme activities, DOM fractions, and Pb bioavailability in riverine sediments, and further explored the response of sediment microbial community to Pb in the presence of MPs. The results indicated that the addition of MPs significantly decreased the adsorption amount of Pb(II) by sediments, especially decreased by 12.6% at 10% MPs treatment. Besides, the changes in enzyme activities, DOM fractions exhibited dose-dependent effects of MPs. The higher level of MPs (5% and 10%) tends to transform Pb into more bioavailable fractions in sediments. Also, MPs amendment was observed to alter sediment bacterial community structures, and community differences were evident in the uncontaminated and lead-contaminated sediments. Therein, significant increase of Bacteroidota, Proteobacteria and decrease of Firmicutes abundance in Pb-contaminated sediment at the phylum level were observed. These findings are expected to provide comprehensive information for assessing the combined ecological risks of heavy metals and MPs in riverine sediments.

Nickel-Based Alloy Dry Milling Process Induced Material Softening Effect.

Improving the cutting efficiency is the major factor for improving the processing of nickel-based alloys. The novelty of this research is the calibrated SiAlON ceramic tool dry milling nickel-based alloy process. Firstly, the nickel-based alloy dry milling process was analyzed through the finite element method, and the required milling force and temperature were deduced. Then, several dry milling experiments were conducted with the milling temperature, and the milling force was monitored. The change in cutting speeds was from 400 m/min to 700 m/min. Experimental results verified the reduction of the dry milling force hypothesized by the simulation. The experiment also indicated that with a cut depth of 0.3 mm, cut width of 6 mm, and feed per tooth of 0.03 mm/z, when milling speed exceeded 527.52 m/min, the milling force began to decrease, and the milling temperature exceeded the nickel-based alloy softening temperature. This indicated that easy cutting could be realized under high-speed dry milling conditions. The interpolation curve about average temperature and average milling forces showed similarity to the tensile strength reduction with the rise of temperature.

Selective recognition and enrichment of carbamazepine in biological samples by magnetic imprinted polymer based on reversible addition-fragmentation chain transfer polymerization.

A well-defined molecularly imprinted polymer (Fe3O4@CS@MIP) was synthesized via reversible addition-fragmentation chain transfer polymerization for magnetic solid-phase extraction coupled with high-performance liquid chromatography-diode array detector to detect carbamazepine (CBZ) in biological samples. The composition of Fe3O4@CS@MIP was selected by a two-step screening method. 4-vinyl pyridine, divinylbenzene and dimethylformamide were chosen as the functional monomer, cross-linker and porogen, respectively. The imprinted layer was coated on the surface of the chain transfer agent-modified magnetic chitosan nanoparticles. The prepared Fe3O4@CS@MIP was characterized by scanning electron microscopy, transmission electron microscopy, Fourier transform infrared spectroscopy, Brunauer-Emmett-Teller measurement and vibrating sample magnetometer. The results indicated that Fe3O4@CS@MIP had a large surface area (265.8 m2/g), high saturation magnetization (19.88 emu/g) and uniform structure. Besides, the binding property of the Fe3O4@CS@MIP was studied in detail. The Fe3O4@CS@MIP showed high imprinting factor (IF = 4.83) and desirable adsorption capacity (323.10 µmol/g) to CBZ. Under the optimum conditions, the developed method exhibited excellent linearity (R2>0.999) in the range of 0.01-0.5 mg/L and 1.0-30.0 mg/L, and the limits of detection were 1.0 µg/L and 9.6 µg/L for the urine and serum samples, respectively. Good recoveries (88.22%-101.18%) were obtained with relative standard deviations less than 4.83%. This work provided a practical approach for the selective extraction and detection of CBZ in real samples.

Improving Dissolution Properties by Polymers and Surfactants: A Case Study of Celastrol.

Two polymorphs of celastrol were discovered and fully characterized by X-ray powder diffraction, thermogravimetry analysis, and differential scanning calorimetry. The single-crystal structures of form I and the isostructural solvate of form II were disclosed by single-crystal X-ray diffraction. The apparent solubility and wettability of both the crystalline forms were determined. It was found that surfactant can significantly improve the solubility of celastrol up to more than 104 times. Tween 80 and sodium dodecyl sulfate largely improved the wettability of the 2 crystals. Form I shows better wettability than form II in all the buffer solutions with polymers and surfactants. Compared with form II, form I exhibits higher solubility in carboxymethylcellulose and polyvinylpyrrolidone media but much lower solubility in tween 80 and sodium dodecyl sulfate solutions. An investigation of wettability and solubility mechanisms was fully explored, and a hypothesis was proposed to understand the abnormal solubility differences.

Delayed total hip arthroplasty after failed treatment of acetabular fractures: an 8- to 17-year follow-up study.

BACKGROUND: Delayed total hip arthroplasty (THA) is a reliable procedure following failed treatment of acetabular fractures. The aim of the present study was to evaluate the influence of the type of fracture treatment and modern ceramic bearing on the clinical outcomes of delayed THA. METHODS: Between January 1997 and January 2008, 33 patients (33 hips) underwent cementless THA after failed acetabular fractures. Twenty-one were initially treated by open reduction internal fixation (ORIF) and 12 had non-ORIF. Joint articulation was either conventional metal-on-polyethylene (MOP) or ceramic-on-ceramic (COC). Intraoperative measures and preoperative and follow-up clinical, radiological, and functional outcomes were compared between the ORIF and non-ORIF groups. RESULTS: Surgery duration, blood loss, and transfusion requirement were greater in the ORIF group than in the non-ORIF group (p < 0.05). Significant improvement in Harris Hip Scores was seen post-surgery in both groups. However, a significant difference in the mean Harris Hip Score was not observed between the two groups (p = 0.57). Six patients in the ORIF group required acetabular reconstructive procedures to address bony defects compared to seven patients in the non-ORIF group (p = 0.09). The rate of anatomical restoration was 58.3% (7/12) in the non-ORIF group and 42.9% (9/21) in the ORIF group (p = 0.12). Radiolucent lines were observed in the MOP group and none in the COC group. Overall survival rate was similar in both groups (p = 0.85): 89.3% in the ORIF group and 87.5% in the non-ORIF group. CONCLUSION: Delayed THA with previous acetabular fractures is a challenging procedure. Initial fracture treatment does not influence the outcome of delayed THA, and modern ceramic bearing has promising results in the long-term follow-up.

Improved dielectric properties of nanocomposites based on poly(vinylidene fluoride) and poly(vinyl alcohol)-functionalized graphene.

In this work, two series of nanocomposites of poly(vinylidene fluoride) (PVDF) incorporated with reduced graphene oxide (rGO) and poly(vinyl alcohol)-modified rGO (rGO-PVA) were fabricated using solution-cast method and their dielectric properties were carefully characterized. Infrared spectroscopy and atom force microscope analysis indicated that PVA chains were successfully grafted onto graphene through ester linkage. The PVA functionalization of graphene surface can not only prevent the agglomeration of original rGO but also enhance the interaction between PVDF and rGO-PVA. Strong hydrogen bonds and charge transfer effect between rGO-PVA and PVDF were determined by infrared and Raman spectroscopies. The dielectric properties of rGO-PVA/PVDF and rGO/PVDF nanocomposites were investigated in a frequency range from 10² Hz to 107 Hz. Both composite systems exhibited an insulator-to-conductor percolating transition as the increase of the filler content. The percolation thresholds were estimated to be 2.24 vol % for rGO-PVA/PVDF composites and 0.61 vol % for rGO/PVDF composites, respectively. Near the percolation threshold, the dielectric permittivity of the nanocomposites was significantly promoted, which can be well explained by interfacial polarization effect and microcapacitor model. Compared to rGO/PVDF composites, higher dielectric constant and lower loss factor were simultaneously achieved in rGO-PVA/PVDF nanocomposites at a frequency range lower than 1 × 10³ Hz. This work provides a potential design strategy based on graphene interface engineering, which would lead to higher-performance flexible dielectric materials.