Preparation and evaluation of PEGylated phospholipid membrane coated layered double hydroxide nanoparticles

AbstractThe aim of the present study was to develop layered double hydroxide (LDH) nanoparticles coated with PEGylated phospholipid membrane. By comparing the size distribution and zeta potential, the weight ratio of LDH to lipid materials which constitute the outside membrane was identified as 2:1. Transmission electron microscopy photographs confirmed the core-shell structure of PEGylated phospholipid membrane coated LDH (PEG-PLDH) nanoparticles, and cell cytotoxicity assay showed their good cell viability on Hela and BALB/C-3T3 cells over the concentration range from 0.5 to 50 μg/mL

Numerical investigation of the opening effect on the mechanical behaviours in rocks under uniaxial loading using hybrid continuum-discrete element method

Openings including their size, shape and distribution in rock play a significant role in the performance of rock related structures. The well-established knowledge in this area can contribute to the engineering practices, for example, underground space design, planning and optimisation in Civil and Mining Engineering and wellbore stability in Drilling Engineering, among others. Thus, understanding the failure mechanism of rock with openings is theoretically and practically meaningful. Laboratory testing on rock or rock-like materials with openings have been studied extensively in the literature, which, however, primarily focuses on the cracks/fractures. In this paper, a comprehensive numerical study on the effect of non-banded openings, i.e., circular, rectangular, and triangular opening, on the rock mechanical behaviour is performed using a hybrid continuum-discrete element method. It is revealed that the proposed simulation method can reproduce reasonably the crack initiation and propagation, and predict well the change of the mechanical behaviour due to the openings. In addition, the influence of the opening shape and opening ratio (=area of opening/specimen area) on the mechanical behaviour is also investigated

Mechanical behavior of sandstone during post-peak cyclic loading and unloading under hydromechanical coupling

This paper investigates mechanical behaviours of sandstone during post-peak cyclic loading and unloading subjected to hydromechanical coupling effect, confirming the peak and residual strengths reduction laws of sandstone with water pressure, and revealing the influence of water pressure on the upper limit stress and deformation characteristics of sandstone during post-peak cyclic loading and unloading. Regarding the rock strength, the experimental study confirms that the peak strength σp and residual strength σr decrease as water pressure P increases. Especially, the normalized strength parameters σp/σpk and σr/σre was negatively and linearly correlated with the P/σ3. Moreover, the Hoek-Brown strength criterion can be applied to describe the relationship between effective peak strength and effective confining stress. During post-peak cyclic loading and unloading, both the upper limit stress σp(i) and crack damage threshold stress σcd(i) of each cycle tend to decrease with the increasing cycle number. A hysteresis loop exists among the loading and unloading stress–strain curves, indicating the unloading deformation modulus Eunload is larger than the loading deformation modulus Eload. Based on experimental results, a post-peak strength prediction model related to water pressure and plastic shear strain is established

“NIR-triggered ROS storage” photodynamic intraocular implant for high-efficient and safe posterior capsular opacification prevention

Posterior capsular opacification (PCO) is the leading cause of vision loss after cataract, mainly caused by the adhesion, proliferation and trans-differentiation of post-operative residual lens epithelial cells (LECs). Effective PCO prevention remains a huge challenge to ophthalmologists and researches for decades. Herein, we developed a “NIR-triggered ROS storage” intraocular implant (CTR-Py-PpIX) based on capsular tension ring (CTR), which is concurrently linked with photosensitizer protophorphyrin IX (PpIX) and energy storage 2-pyridone derivative (Py), to guarantee instantaneous and sustainable ROS generation for LECs killing, aiming to achieve more efficient and safer photodynamic therapy (PDT) to effectively prevent PCO. The silylated PpIX-Si and Py-Si were covalently conjugated to the plasma activated CTR surface to obtain CTR-Py-PpIX. Results demonstrated that CTR-Py-PpIX had dual functions of PDT and battery, in which PpIX could generate ROS extracellularly under irradiation, with one part directly inhibiting LECs by lipid peroxidation (LPO) induction of cell membranes. Meanwhile, the excess ROS stored in Py could be continuously released to amplify LPO levels after the irradiation was removed. Ultimately, the proliferation of LECs in capsular bag was completely inhibited under mild irradiation conditions, achieving a sustainable and controlled PDT effect for effective PCO prevention with good biocompatibility. This NIR-triggered ROS storage intraocular implant would provide a more efficient and safer approach for long-term PCO prevention

Injectable, NIR/pH-Responsive Nanocomposite Hydrogel as Long-Acting Implant for Chemophotothermal Synergistic Cancer Therapy

In this study, gold nanorods (GNRs) were incorporated into the hydrogel networks formed by the copolymerization of <i>N</i>-isopropylacrylamide (NIPAm) and methacrylated poly-β-cyclodextrin (MPCD)-based macromer to fabricate an injectable and near-infrared (NIR)/pH-responsive poly­(NIPAm-<i>co</i>-MPCD)/GNRs nanocomposite hydrogel, which could serve as a long-acting implant for chemophotothermal synergistic cancer therapy. The nanocomposite hydrogel showed superior mechanical and swelling properties, gelation characteristics, and excellent NIR-responsive property. A hydrophobic acid-labile adamantane-modified doxorubicin (AD-DOX) prodrug was loaded into the hydrogel efficiently by host–guest interaction. The nanocomposite hydrogel exhibited a manner of sustained drug release and could sustain the slow and steady release of DOX for more than 1 month. The pH-responsive release of DOX from the nanocomposite hydrogel was observed owing to the cleavage of acid-labile hydrazone bond between DOX and the adamantyl group in acidic environment. NIR irradiation could accelerate the release of DOX from the networks, which was controlled by the collapse of the hydrogel networks induced by photothermal effect of GNRs. The in vitro cytotoxicity test demonstrated the excellent biocompatibility and photothermal effect of the nanocomposite hydrogel. Moreover, the in situ-forming hydrogel showed promising tissue biocompatibility in the mouse model study. The in vivo antitumor test demonstrated the capacity of the nanocomposite hydrogel for chemophotothermal synergistic therapy with reduced adverse effects owing to the prolonged drug retention in the tumor region and efficient photothermal effect. Therefore, this injectable and NIR/pH-responsive nanocomposite hydrogel exhibited great potential as a long term drug delivery platform for chemophotothermal synergistic cancer therapy