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Polyethylene terephthalate) (PET) nanocomposites containing multi-walled carbon nanotubes (MWNT) of different diameters and aspect ratios were prepared by coagulation method. The diameter and aspect ratio MWNT with the same mass percent shows substantial effects on crystallization behavior and electrical conductivity of PET. FESEM observations show that the diameter of MWNT could affect their interactions with the surrounding PET and the thickness of interfacial PET layer. High aspect ratio of MWNT can facilitate the overlapping of MWNT and the formation of conductive networks. The electrical performance of PET/MWNT nanocomposites can be tuned by controlling the thickness of interfacial polymer layer and the aspect ratios of MWNT. The smallest diameter MWNT possesses the strongest interfacial interactions with the PET chains, leading to the most noticeable increase in nucleating effect and crystal growth rate. Moreover, MWNT with high aspect ratio can facilitate the growth and development of PET crystals due to the greater nucleating efficiency and less restricted effect to PET crystallization. However, MWNT with small aspect ratio owns much more nucleation sites than MWNT with high aspect ratio at the same loadings, which may enhance nucleation density and nucleation rate of PET crystallization, but result in slower PET crystal growth and broader crystal size distributions., INTRODUCTION Since their discovery in 1990s, carbon nanotubes (CNT) have attracted much attention throughout the academic and industrial world owing to their extraordinary mechanical, electrical and thermal properties, together with [...]

Crystallization and stress relaxation behaviors of ultrahigh molecular weight polyethylene (UHMWPE) doped with carbon nanotubes (CNTs) have been investigated by X‐ray diffraction, differential scanning calorimetry (DSC) and single strand strength testing. Compared with UHMWPE, crystallinity of the UHMWPE/CNT composites significantly increases from 71.95 to 82.92% while crystallization activation energy decreases from 679.4 to 535.8 KJ/mol. CNTs as the nucleating agent changes the nucleation type of UHMWPE from homogenous to heterogeneous and accelerates the nucleation and growing of crystalline grains. Above crystallization changes also affect the mechanical properties of the UHMWPE/CNTs composites. Stress relaxation testing indicates that the relaxation stability of UHMWPE/CNT composites increases while the relaxation rate decreases. J. VINYL ADDIT. TECHNOL., 24:229–232, 2018. © 2016 Society of Plastics Engineers [ABSTRACT FROM AUTHOR]

The acquisition of multidrug resistance (MDR) is a major hurdle for the successful chemotherapy of tumors. Herein, a novel hybrid micelle with pH and near-infrared (NIR) light dual-responsive property is reported for reversing doxorubicin (DOX) resistance in breast cancer. The hybrid micelles are designed to integrate the pH- and NIR light-responsive property of an amphiphilic diblock polymer and the high DOX loading capacity of a polymeric prodrug into one single nanocomposite. At physiological condition (i.e., pH 7.4), the micelles form compact nanostructure with particle size around 30 nm to facilitate blood circulation and passive tumor targeting. Meanwhile, the micelles are quickly dissociated in weakly acidic environment (i.e., pH ≤ 6.2) to release DOX prodrug. When exposed to NIR laser irradiation, the hybrid micelles can trigger notable tumor penetration and cytosol release of DOX payload by inducing tunable hyperthermia effect. In combination with localized NIR laser irradiation, the hybrid micelles significantly inhibit the growth of DOX-resistant MCF-7/ADR breast cancer in an orthotopic tumor bearing mouse model. Taken together, this pH and NIR light-responsive micelles with hyperthermia-triggered tumor penetration and cytoplasm drug release can be an effective nanoplatform to combat cancer MDR. [ABSTRACT FROM AUTHOR]

ZL-004, a promising small molecule that increases white blood cell counts, was developed for extended-release nanosuspensions to improve low solubility and compliance of patients. In vivo pharmacokinetic studies of nanosuspensions with different particle sizes and administration volumes were conducted. Unexpectedly, Cmax of NS-PC-L (1156 nm) was 1.3 fold higher than NS-PB-L (836 nm), and area under plasma concentration-time curve (AUC) was similar. It suggested that in vivo behavior of nanosuspensions was influenced significantly by the original dissolved drug, which did not only rely on the particle size but also the amount of the free stabilizers. In addition, smaller administration volume (0.1 mL) achieved significantly lower Cmax and AUC than the higher volume (0.5 mL), due to the reduced amount of dissolved drug. DSC and XPRD demonstrated that the crystal forms of nanosuspensions prepared by the precipitation method and high-pressure homogenization were similar; therefore, in vivo behaviors did not show significant differences. An additional 0.15% PEG 4000 enhanced the redispersity and maintained the particle size for 3 months. Finally, a nanosuspensions with the desired initial release was achieved, which lasted approximately 32 days steadily after a single dose. AUC and t1/2 were 161.2 fold and 22.9 fold higher than oral administration. [ABSTRACT FROM AUTHOR]

On page 2489 H. Yu, Y. Li, and co‐workers report a pH and near‐infrared light responsive micelle for combating cancer multidrug resistance (MDR). The micelles induce moderate hyperthermia effect upon NIR laser illumination to facilitate their tumor penetration and lysosome escape, thus improving the therapeutic efficacy of doxorubicin. This study implies a novel strategy for treatment of MDR cancer. [ABSTRACT FROM AUTHOR]

ZL-004, a promising small molecule that increases white blood cell counts, was developed for extended-release nanosuspensions to improve low solubility and compliance of patients. In vivo pharmacokinetic studies of nanosuspensions with different particle sizes and administration volumes were conducted. Unexpectedly, C max of NS-PC-L (1156 nm) was 1.3 fold higher than NS-PB-L (836 nm), and area under plasma concentration-time curve (AUC) was similar. It suggested that in vivo behavior of nanosuspensions was influenced significantly by the original dissolved drug, which did not only rely on the particle size but also the amount of the free stabilizers. In addition, smaller administration volume (0.1 mL) achieved significantly lower C max and AUC than the higher volume (0.5 mL), due to the reduced amount of dissolved drug. DSC and XPRD demonstrated that the crystal forms of nanosuspensions prepared by the precipitation method and high-pressure homogenization were similar; therefore, in vivo behaviors did not show significant differences. An additional 0.15% PEG 4000 enhanced the redispersity and maintained the particle size for 3 months. Finally, a nanosuspensions with the desired initial release was achieved, which lasted approximately 32 days steadily after a single dose. AUC and t 1/2 were 161.2 fold and 22.9 fold higher than oral administration.

The combination of chemotherapy and RNA interference is a promising approach for efficient cancer therapy. However, the success of such a strategy is hampered by the lack of suitable vectors to coordinate small interfering RNA (siRNA) and chemotherapeutic drug into one single platform. We herein report a novel triple-layered pH-responsive micelleplex loading siRNA and alkylated cisplatin prodrug for NF-Kappa B targeted treatment of metastatic breast cancer. The micelles were self-assembled from poly(ethylene glycol)-block-poly(aminolated glycidyl methacrylate)-block-poly(2-(diisopropyl amino) ethyl methacrylate) (PEG-b-PAGA-b-PDPA) triblock copolymers. At pH 7.4, the cisplatin prodrug was encapsulated in the hydrophobic PDPA core and siRNA was loaded on the positively charged PAGA interlayer to form the micelleplexes. The PEG corona can prevent protein absorption during blood circulation, minimize non-specific interaction with the reticuloendothelial system, and prolong the systemic circulation of the micelleplexes. The positively charged PAGA interlayer can facilitate deep tumor penetration of the micelleplexes, which, upon cellular uptake, are dissociated in the early endosomes to release anticancer drug payload due to protonation of the PDPA core. Using a 4T1 breast cancer model, we demonstrate that this novel micelleplex co-loaded with cisplatin prodrug and siRNA-p65 is able to simultaneously inhibit tumor growth and suppress distant metastasis of the cancer cells by downregulating NF-kappa B expression. The results reported in this study suggest that siRNA and anticancer drug co-delivery using pH-responsive micelleplexes is a promising strategy for efficient treatment of metastatic cancer.