Poly(sulfobetaine) versus poly(ethylene glycol) based copolymer modified polyurethane catheters for antifouling.

Polyurethane (PU) catheters are commonly used in clinical treatment. However, the hydrophobic nature of the PU catheter surface leads to adhesion or adsorption to platelets, proteins, bacteria, and other molecules when used in human treatment. To achieve a surface with strong hydrophilicity, high stability and excellent biocompatibility, it is necessary to functionalize the PU catheters. In this paper, a coating with antifouling function was constructed on the surface of PU catheters using plasma technology and an amide coupling reaction. A series of characterization methods, including X-ray photoelectron spectroscopy (XPS), water contact angles (WCA), and atomic force microscopy (AFM), were used to prove the successful modification of the polymer coatings. The coatings showed good stability under conditions such as PBS (pH 7.4, 720 h), 75% ethanol (6 h) and 1 wt% SDS (10 min). Additionally, the coatings exhibit excellent hemocompatibility and antibacterial properties. The PU/PEI/PCSB coating has the best anti-fouling performance among them, which means that using the PCSB copolymer has the potential to modify different clinical catheters into highly effective antifouling coatings.

Phosphorylcholine zwitterionic shell-detachable mixed micelles for enhanced cancerous cellular uptakes and increased DOX release.

To further enhance the cancerous cellular uptakes and increase the drug release of the drug loaded micelles, herein, we fabricated a series of mixed micelles with different mass ratios using two amphiphilic copolymers P(DMAEMA-co-MaPCL) and PCL-SS-PMPC. The mixed micelles showed a prolonged circulation time due to the zwitterionic shells in a physiological environment (pH 7.4). In addition, because of the protonation of tertiary amine groups in PDMAEMA and the breakage of the disulfide bond in PMPC-SS-PCL in a tumor microenvironment, the mixed micelles aggregated, which led to enhanced cancerous cellular penetration and increased DOX release. Moreover, cytotoxicity assay showed that the mixed micelles had good biocompatibility to L929, HeLa and MCF-7 cells, even at a concentration of up to 1 mg mL-1. Furthermore, enhanced antitumour activity and cellular uptake of HeLa and MCF-7 cells were detected after loading with DOX, which was determined by confocal laser scanning microscopy (CLSM) and flow cytometry (FC), especially for the DOX@MIX 3 micelles (20% mass ratio of the P(DMAEMA-co-MaPCL)). Therefore, the mixed strategy provides a simple and efficient ways to promote anticancer drug delivery.

Construction of Folate-Conjugated and pH-Responsive Cell Membrane Mimetic Mixed Micelles for Desirable DOX Release and Enhanced Tumor-Cellular Target.

Smart multifunctional polymeric micelles are in urgent demand for future cancer diagnosis and therapy. In this paper, doxorubicin (DOX)-loaded folic acid (FA)-targeting and pH-responsive cell membrane mimetic mixed micelles of P(DMAEMA-co-MaPCL) (PCD) and FA-P(MPC-co-MaPCL) (PMCF) (mass ratio 5/5) were prepared by a dialysis method. The micelle size, morphology, X-ray powder diffraction (XRD), pH responsiveness, in vitro DOX release, cytotoxicity, and cellular uptake were studied in detail. The results indicated that DOX could be efficiently loaded into mixed micelles (PDMCF micelles), and the DOX-loaded mixed micelles (DOX@PDMCF micelles) exhibited a size of 150 nm and pH-responsive DOX release in an extended period. Furthermore, the DOX@PDMCF micelles could efficiently suppress the proliferation of tumor cells, HeLa and MCF-7 cells. Our data suggest that the DOX@PDMCF micelles have the potential to be applied in tumor therapy, especially for treating various folate receptor overexpressed tumors.

The V-ATPase regulates localization of the TRP Ca2+ channel Yvc1 in response to oxidative stress in Candida albicans.

The vacuolar-type H+-ATPase (V-ATPase) is a highly conserved protein complex among the eukaryotic cells. We previously revealed that both the V-ATPase and the transient receptor potential (TRP) channel Yvc1 are involved in oxidative stress response (OSR). However, the relationship between V-ATPase and Yvc1 during OSR remains unknown. In this study, disruption of the V-ATPase-encoding genes VPH2 and TFP1, similar with disruption of YVC1, caused H2O2 hypersensitivity and enhancement of vacuolar membrane permeability (VMP) under oxidative stress. Further investigations showed that unlike the wild type strain with vacuole membrane-localized Yvc1, both vph2Δ/Δ and tfp1Δ/Δ had Yvc1 localization in the vacuole cavity, indicating that disruption of VPH2 or TFP1 impaired normal vacuolar membrane-localization of Yvc1. Interestingly, addition of CaCl2 alleviated the growth defect of vph2Δ/Δ and tfp1Δ/Δ under oxidative stress, leading to prevention of VMP, decrease in ROS levels and activation of OSR. In contrast, addition of the Ca2+ chelating agent glycol-bis-(2-aminoethylether)-N,N,N',N'-tetraacetic acid (EGTA) aggravated H2O2 hypersensitivity of the mutants. These results showed that the V-ATPase plays an important role in maintenance of normal Yvc1 localization, which contributes to Ca2+ transport from the vacuoles to the cytosol for activation of OSR. This work sheds a novel light on the interaction between V-ATPase and Ca2+ transport for regulation of OSR in C. albicans.

The TRP Ca2+ channel Yvc1 regulates hyphal reactive oxygen species gradient for maintenance of polarized growth in Candida albicans.

Candida albicans is an important opportunistic fungal pathogen, and hyphal polarized growth is critical for its invasive infection to the host. Both the vacuolar transient receptor potential (TRP) Ca2+ channel Yvc1 and the NADPH oxidase Fre8-governed reactive oxygen species (ROS) gradient are involved in hyphal development, but the relationship between Yvc1 and Fre8 during hyphal polarized growth remains to be investigated. Herein, we found that deletion of YVC1 led to dispersed distribution of ROS along the germ tube, while it was concentrated at the hyphal tip in WT cells. Moreover, Fre8 localization was altered as YVC1 was disrupted. Besides, similar to deletion of YVC1, addition of the Ca2+ chelating agent EGTA caused depolarization of Fre8-GFP in the wild-type cells, indicating the critical role of Yvc1-maintained Ca2+ gradient in polarized distribution of Fre8-GFP and consequent disruption of tip ROS gradient. By constructing a series of GFP-tagged polarized growth-related proteins, including Bud6, Exo70 and Lifeact, we found that these proteins, similar to Fre8 and ROS, had depolarized localization in yvc1Δ/Δ. Thus, our work provides a mechanic explanation of Yvc1-governed and ROS-related hyphal polarized growth, and shed a novel light on the role of Ca2+ signaling in maintenance of redox homeostasis and morphogenesis in the fungal pathogens.