Regulation of Nucleotide Metabolism with Nutrient-Sensing Nanodrugs for Cancer Therapy

The continual growth of tumor cells requires considerable nutrient consumption. Methotrexate (MTX) is used to treat certain types of cancer by blocking the DNA and RNA productions through interfering one-carbon metabolism and de novo purine and pyrimidine synthesis. However, treatment of MTX may cause many serious adverse effects, which hamper its clinical application. Herein, the authors synthesize ferrous ions, histidine, and MTX assembled nanoparticles (FHM) to deliver MTX at tumor site and enhance the sensitivity of tumor cells to MTX with histidine catabolism. Furthermore, fasting-mimicking diet (FMD) is applied to intervene in the one-carbon metabolism and enhance the cytotoxicity of MTX. Meanwhile, FMD treatment can significantly augment the cellular uptake and tumor accumulation of FHM nanoparticles. Due to the triple inhibitions of the one-carbon metabolism, the proliferation of tumor cells is strongly disturbed, as which is highly replying on DNA and RNA production. Taken together, a 95% lower dose of MTX adopted in combined therapy significantly inhibits the growth of two types of murine tumors without evident systemic toxicity. This strategy may provide a promising nucleotide metabolism-based nanomedicine for cancer therapy.

Phase Behavior and Thermo-Mechanical Properties of IF-WS2 Reinforced PP-PET Blend-Based Nanocomposites

The industrial advancement of high-performance technologies directly depends on the thermo-mechanical properties of materials. Here we give an account of a facile approach for the bulk production of a polyethylene terephthalate (PET)/polypropylene (PP)-based nanocomposite blend with Inorganic Fullerene Tungsten Sulfide (IF-WS₂) nanofiller using a single extruder. Nanofiller IF-WS₂ was produced by the rotary chemical vapor deposition (RCVD) method. Subsequently, IF-WS₂ nanoparticles were dispersed in PET and PP in different loadings to access impact and their dispersion behavior in polymer matrices. As-prepared blend nanocomposites were characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), thermogravimetric analysis (TGA), dynamic differential scanning (DSC), dynamic mechanical analysis (DMA), and X-ray diffraction (XRD). In this work, the tensile strength of the PP/PET matrix with 1% IF-WS₂ increased by 31.8%, and the thermal stability of the sample PP/PET matrix with 2% increased by 18 °C. There was an extraordinary decrease in weight loss at elevated temperature for the nanocomposites in TGA analysis, which confirms the role of IF-WS₂ on thermal stability versus plain nanocomposites. In addition, this method can also be used for the large-scale production of such materials used in high-temperature environments.

Melt-Processed Poly(Ether Ether Ketone)/Carbon Nanotubes/Montmorillonite Nanocomposites with Enhanced Mechanical and Thermomechanical Properties

The agglomeration problem of nanofillers, for instance, carbon nanotubes (CNTs) in a poly(ether ether ketone) (PEEK) matrix, is still a challenging assignment due to the intrinsic inert nature of PEEK to organic solvents. In this work, organically modified montmorillonite (MMT) was introduced as a second filler for improving the dispersion of CNTs in the PEEK matrix and enhancing the mechanical properties, as well as reducing the cost of the materials. The nanocomposites were fabricated through melt-mixing PEEK with CNTs/MMT hybrids, which were prepared in advance by mixing CNTs with MMT in water. The introduction of MMT improved the dispersion stability of CNTs, as characterized by sedimentation and zeta potential. The CNTs/MMT hybrids were maintained in PEEK nanocomposites as demonstrated by the transmission electron microscope. The mechanical and thermomechanical measurements revealed that CNTs together with MMT had a strong reinforcement effect on the PEEK matrix, especially at high temperature, although it had a negative effect on the toughness. A maximum increase of 48.1% was achieved in storage modulus of PEEK nanocomposites with 0.5 wt% CNTs and 2 wt% MMT at 240 °C, compared to that of neat PEEK. The differential scanning calorimetry results revealed that CNTs accelerated the crystallization of the PEEK matrix while a further addition of MMT played an opposite role. The nucleation activity of the fillers was also evaluated by the Dobreva method.