Boron-Based Polyphosphazene-Functionalized Mxene Nanosheets for Polypropylene Composites with Improved Mechanical Properties and Flame Retardancy Applications

Developing high-performance resins with exceptional thermal oxidation stability, flame retardancy, smoke release suppression, and mechanical properties is an important industrial challenge. However, current flame-retardant design strategies often compromise other composite material properties. Especially when using polyolefin, unsaturated polyester, and other noncharred materials, it is usually necessary to add large amounts of flame-retardant fillers. In this study, a nanosynergist (Ti3C2Tx@PPD) for functionalizing Ti3C2Tx nanosheets with boron-based polyphosphazene was designed and adopted for a piperazine pyrophosphate/polypropylene (PAPP/PP) system as an application example. By controlling the chemical environment of cyclotriphosphazene, the condensed phase characteristics of polyphosphazene were preserved, but also an atypical vapor phase flame-retardant mechanism was activated. The combination of P/N/B elements and Ti3C2Tx exhibited excellent catalytic char-forming performance compared to others in the literature. Only 2% of incorporated Ti3C2Tx@PPD reduced the total heat released from the composite by 66.3%, the total smoke released by 71.8%, and the fire growth index by 49.4%. The incorporation of Ti3C2Tx@PPD inhibited deterioration of the mechanical properties of the composite. In addition, the pyrolysis path of Ti3C2Tx was revealed under a special environment. This study lays the foundation for the functional design of Ti3C2Tx nanomaterials that can be used in various applications that require high-performance resins

Innovative Design and Preparation of Hierarchical BP–OH@HAP Structure: Study on Flame Retardancy and Mechanical Characteristics of UPR Nanocomposites

The flammability and brittleness of unsaturated polyester resin (UPR) were two serious problems that limited its application in high-precision fields. Here, the rod-shaped hydroxyapatite (HAP) was anchored on the surface of hydroxylated black phosphorus nanosheets (BP–OH) through a hydrothermal reaction to obtain a highly stable black phosphorus-based nano flame retardant (BP–OH@HAP). Owing to the exposure of many hydroxyl groups, BP–OH@HAP was well dispersed in the UPR matrix, and UPR nanocomposites with 0.5 wt % BP–OH@HAP realized a 71% increase in impact strength. The presence of BP–OH@HAP also greatly inhibited the combustion of UPR nanocomposites. In detail, the UPR composites with 2 wt % BP–OH@HAP achieved a 47.0% decrease in peak heat release rate (PHRR) along with 23.1% reductions in total heat release (THR), revealing the excellent ability of BP–OH@HAP to inhibit polymer combustion. In addition, UPR/BP–OH@HAP 2.0 achieved a 46 s increase in the time to PHRR (tPHRR) and a 62% reduction in the fire growth index (FGI), indicating that the fire spread of UPR/BP–OH@HAP 2.0 was significantly suppressed. Therefore, this work obtained the UPR/BP–OH@HAP nanocomposite with high fire safety through the innovation of inorganic nanotechnology, which provided new research ideas for improving the toughness and flame-retardant properties of UPR-based nanocomposites

Effects on the cell cycle progression of ZR-75-1 cells treated with trastuzumab or fulvestrant or with a combination of both.

Effects on the cell cycle progression of ZR-75-1 cells treated with trastuzumab or fulvestrant or with a combination of both.</p

Effects on the cell cycle progression of BT-474 cells after continuous exposure to trastuzumab and fulvestrant as single agents or in combination for 72h.

Trastuzumab and fulvestrant as single agents or as a combination promoted the accumulation of BT-474 cells in the G1 phase of the cell cycle. However, no statistically significant differences were detected between the combination treatment group and individual drug-treated groups (P>0.05). The cell cycle stage distribution of BT-474 cells in the five different groups are shown in S4 Fig of the supplementary information section. * P<0.05 compared with control group.</p

Effects on the cell cycle stage distribution of ZR-75-1 cells after continuous exposure to trastuzumab and fulvestrant as single agents or in combination.

Trastuzumab and fulvestrant used as single agents promoted a statistically significant accumulation of ZR-75-1 cells in the G1 phase of the cell cycle when compared to the control groups. The combination of trastuzumab and fulvestrant caused a statistically significant further increase in the percentage of ZR-75-1 cells in the G1 phase compared with the effect of fulvestrant alone (P = 0.030). * PS3 Fig of the supplementary information section.</p

Combinatorial use of trastuzumab and fulvestrant (CalcuSyn).

Combinatorial use of trastuzumab and fulvestrant (CalcuSyn).</p

An Experimental Analysis of the Molecular Effects of Trastuzumab (Herceptin) and Fulvestrant (Falsodex), as Single Agents or in Combination, on Human HR+/HER2+ Breast Cancer Cell Lines and Mouse Tumor Xenografts

<div><p>Purpose</p><p>To investigate the effects of trastuzumab (herceptin) and fulvestrant (falsodex) either in combination or alone, on downstream cell signaling pathways in lab-cultured human HR+/HER2+ breast cancer cell lines ZR-75-1 and BT-474, as well as on protein expression levels in mouse xenograft tissue.</p><p>Methods</p><p>Cells were cultivated in the presence of trastuzumab or fulvestrant or both. Molecular events that resulted in an inhibition of cell proliferation and cell cycle progression or in an increased rate of apoptosis were studied. The distribution and abundance of the proteins p-Akt and p-Erk expressed in these cells in response to single agents or combinatorial treatment were also investigated. In addition, the effects of trastuzumab and fulvestrant, either as single agents or in combination on tumor growth as well as on expression of the protein p-MED1 expressed in <i>in vivo</i> mouse xenograft models was also examined.</p><p>Results</p><p>Cell proliferation was increasingly inhibited by trastuzumab or fulvestrant or both, with a CI<1 and DRI>1 in both human cell lines. The rate of apoptosis increased only in the BT-474 cell line and not in the ZR-75-1 cell line upon treatment with fulvestrant and not trastuzumab as a single agent (P<0.05). Interestingly, fulvestrant, in combination with trastuzumab, did not significantly alter the rate of apoptosis (in comparison with fulvestrant alone), in the BT-474 cell line (P>0.05). Cell accumulation in the G1 phase of cell cycle was investigated in all treatment groups (P<0.05), and the combination of trastuzumab and fulvestrant reversed the effects of fulvestrant alone on p-Akt and p-Erk protein expression levels. Using ZR-75-1 or BT-474 to generate <i>in vivo</i> tumor xenografts in BALB/c athymic mouse models, we showed that a combination of both drugs resulted in a stronger inhibition of tumor growth (P<0.05) and a greater decrease in the levels of activated MED1 (p-MED1) expressed in tumor issues compared with the use of either drug as a single agent.</p><p>Conclusions</p><p>We demonstrate that the administration of trastuzumab and fulvestrant in combination results in positive synergistic effects on both, ZR-75-1 and BT-474 cell lines. This combinatorial approach is likely to reduce physiological side effects of both drugs, thus providing a theoretical basis for the use of such combination treatment in order to resolve HR+/HER2+ triple positive breast cancer that has previously been shown to be resistant to endocrine treatment alone.</p></div

Effects on the levels of the proteins p-Akt and p-Erk extracted from ZR-75-1 cells either untreated or cultured in the presence of vehicle or trastuzumab at ED₅₀ or fulvestrant at ED₅₀ or with a combination of both for 72h.

p-Akt and p-Erk proteins from two samples in the control group and vehicle group and from three samples in each treatment group were detected. It was found that trastuzumab decreased p-Akt levels and that fulvestrant increased both, p-Akt and p-Erk levels. In addition, the combination of both drugs significantly reduced levels of p-Akt and notably inhibited the effect that fulvestrant had on the levels of both proteins. * P<0.05 compared with control group. ** P<0.05 compared with combination group.</p

Effects on ZR-75-1 cell apoptosis treated with trastuzumab and fulvestrant as single agents or with a combination of both.

<p>Effects on ZR-75-1 cell apoptosis treated with trastuzumab and fulvestrant as single agents or with a combination of both.</p

Effects on the cell cycle progression of BT-474 cells treated with trastuzumab or fulvestrant or with a combination of both.

<p>Effects on the cell cycle progression of BT-474 cells treated with trastuzumab or fulvestrant or with a combination of both.</p