Analysis of tizoxanide,active metabolite of nitazoxanide,in rat brain tissue and plasma by UHPLC–MS/MS

Tizoxanide, the active metabolite of nitazoxanide, has recently been reported as an effective agent for the treatment of glioma. As there had been no report about the analysis of tizoxanide in brain tissue, we established extraction and UHPLC–MS/MS methods to quantify tizoxanide in rat brain and plasma to evaluate the brain-to-plasma ratio of tizoxanide. The biological samples were mainly prepared by acetonitrile and the separation was performed on a Waters XBridge® BEH C₁₈ column. The mobile phase was composed of water mixed with 10 mm ammonium formate (pH 3.0) and acetonitrile according a gradient volume. Tizoxanide and topiramate (internal standard) were monitored utilizing negative electron spray ionization in multiple reaction monitoring mode. The methods were validated to be precise and accurate within the dynamic range of 5–1000 ng/mL and 0.2–50 ng/g for plasma and brain tissue samples, respectively. The lower limit of quantitation of the method was 0.2 ng/g, which was far more sensitive than all existing methods to quantify tizoxanide in biological samples. Application performed on rats exhibited that the brain-to-plasma ratio of tizoxanide ranged from 3.16 to 26.86% in 1 h after administration of 10 mg/kg nitazoxanide.     

Piezoelectric Performance of Microcellular Polypropylene Foams Fabricated Using Foam Injection Molding as a Potential Scaffold for Bone Tissue Engineering

Abstract

Piezoelectric properties and adequate porosity play important roles in bone tissue engineering. In this paper we describe the fabrication of piezoelectric polypropylene (PP) foam using injection molding to be utilized as a potential cost-effective scaffold for bone tissue engineering. One-side mechanical skin removal from the foam was used to investigate the effect of the solid skin on the piezoelectric performance. The microcellular structure, relative density, crystalline structure, mechanical properties, piezoelectric properties under repeated impact pressure and biocompatibility of the scaffolds were investigated using scanning electron microscopy (SEM), water displacement method, differential scanning calorimetry (DSC), uniaxial tension tests, piezoelectric tests and MTT assays, respectively. Uniform spherical cells, with an average size of 75?µm and a density of 1.23?×?10⁶ cells/cm^?3, suitable for bone regeneration, were imaged by SEM. The DSC results showed β crystals formation in the PP foam during the foaming process which would be valuable for mechanical properties. The foaming process did not reduce the mechanical properties significantly. The foaming process promoted the piezoelectric responses by 134, 922, and 87%, respectively, for the PP samples with 3, 2 and 1?mm thickness. The biocompatibility test suggested improved cellular biocompatibility by foaming. Overall, the results demonstrated the development of a cost-effective scaffold for tissue engineering.     

3D Printed Anchoring Sutures for Permanent Shaping of Tissues

Sutures are one of the most widely used devices for adhering separated tissues after injury or surgery. However, most sutures require knotting, which can create a risk of inflammation, and can act as mechanically weak points that often result in breakage and slipping. Here, an anchoring suture is presented with a design that facilitates its propagation parallel to the suturing direction, while maximizing its resistive force against the opposite direction of external force to lock its position in tissues. Different microstructures of suture anchors are systematically designed using orthogonal arrays, and selected based on shape factors associated with mechanical strength. 3D printing is used to fabricate different types of hollow microstructured suture anchors, and optimize their structure for the effective shaping of tissues. To define the structural design for fixing tissues, the maximum force required to pull 3D printed anchors in different directions is examined with tissues. The tissue reshaping function of suture anchors is further simulated ex vivo by using swine ear, nose, and skin, and bovine muscle tendon. This study provides advantages for building functional sutures that can be used for permanently reshaping tissues with enhanced mechanical strength, eliminating the need for knotting to improve surgical efficiency.     

Minimally Invasive & Long‐lasting Neural Probes from a Materials Perspective

Neurological disorders in aging society have created the need to understand how the brain works. At present, there are limited engineered “non‐invasive” tools to study and characterize the brain activity. Advancement in neuroscience research is highly focused on the fabrication of implantable neural probes that can effectively integrate with the neural tissue. Challenges associated with the commercially available probes has driven the development of mechanically compliant and non‐invasive neural implants. Engineering the mechanical and electrical performance of these probes is necessary to obtain tremendous sensitivity and selectivity along with chronic functionality. Selection of proper materials and understanding their fundamentals plays an essential role in achieving the desired neural interface. In this review, we have highlighted the recent progress in the utilization of new materials to attain a neural probe with improved flexibility, biocompatibility and signal quality.     

Pharmacokinetics and tissue distribution of trans-ferulic acid-4-β-glucoside in rats using UPLC–MS/MS

Trans-ferulic acid-4-β-glucoside (FAG) is a monomer extracted from Radix Aconiti Lateralis Preparata, which is a potential candidate for the prevention and treatment of cold injury. To determine the concentration of FAG in rats, it is essential to develop an ultra-performance liquid chromatography coupled with MS/MS method. Chromatographic separation was achieved by an Acquity UPLC BEH C18 column (2.1 × 50 mm, 1.7 μm). A Xevo triple quadrupole tandem mass spectrometer was used to quantitatively determine FAG in the negative-ion mode. The standard calibration curve was linear over the concentration range of 0.1–100 μg/mL and 0.0626–31.28 μg/g for rat plasma and liver tissue homogenate samples, respectively. The inter- and intra-batch precision (% relative standard deviation) of the assay was ≤8.29%, and accuracy (% relative error) ranged from −7.41 to 10.99%. The matrix effect was between 92.99 and 102.39%. The oral absolute bioavailability of FAG was obtained as 1.80%. The results of tissue distribution suggested that FAG spread rarely in the liver and brown adipose, which was not propitious to exert its ability to treat cold injury. In general, these studies were significant to provide necessary information for further study.     

调控细胞迁移和组织再生的生物材料研究

组织再生材料为细胞、组织的生长提供必要的物质基础,维持再生组织的形状和力学性能,并实现与周围组织的有机整合。其中,材料-细胞的相互作用是组织再生材料的核心问题。组织再生材料表界面的物理结构和化学性能可以直接影响细胞的黏附、铺展、增殖、迁移和分化等行为,进而影响组织修复和再生的效果。多数组织和器官具有立体结构,并具有更为精细的微结构。因此,三维组织再生材料体系的构建及其微结构调控是另外一个重要问题。本文结合本课题组近年的工作,综合国内外最新研究成果,重点介绍了生物材料表界面物理结构和理化性质对微粒吞噬、细胞黏附的影响、梯度材料对细胞黏附和定向迁移的作用、3D水凝胶中的细胞迁移行为及特点,以及用于皮肤和软骨组织修复与再生的植入材料,最后对生物材料在组织再生中的研究与应用进行了展望。     

Laser irradiation desorption of microcystins from protein complex in fish tissue and liquid chromatography‐tandem mass spectrometry analysis

Microcystins are a group of cyanotoxins which interact with the C‐terminal region of PP1 and PP2A proteins, so denaturation and inactivation are necessary for breaking covalent binding to release microcystins. In this study, a novel extraction method was developed by laser irradiation desorption of microcystins from fish protein. The sample was mixed with aqueous methanol and irradiated by a 450 nm laser, with an optimized value of laser power density at 8 W and exposure time at 5 min. ThenLC–MS/MS was applied for the determination of microcystins in fish extracts. The ionization behaviors of microcystins were investigated firstly, and doubly charged microcystins were selected as precursor ions in multiple reaction monitoring scan for quantification. This proposed quantitative method was well validated in terms of selectivity, linearity, sensitivity, accuracy, recovery, and stability. The successful application of this LC–MS/MS method showed its ability for the analysis of microcystins in low concentration, and it would be of significant interest for environmental and food safety applications to ensure the safety of fish and related products.     

Modifying the Pores of an Inverse Opal Scaffold With Chitosan Microstructures for Truly Three‐Dimensional Cell Culture

Inverse opal scaffolds have recently emerged as a novel class of scaffolds with uniform and controllable pore sizes for tissue engineering to provide better nutrient transport, a uniform cell distribution, and an adjustable microenvironment for cell differentiation. However, when the pore size of the scaffold is much larger than the dimension of a cell, the cell actually encounters a local 2D environment and the void space associated with the pore can not be efficiently utilized. Here, we demonstrate that a truly 3D microenvironment can be created inside a pore by further functionalizing the as‐prepared inverse opal scaffold with a second polymer by freeze‐drying. The resultant inverse opal scaffold with hierarchically structured pores can enhance both cell proliferation and tissue infiltration.     

Detection of nickel in fish organs with a two-photon fluorescent probe

Molecular imaging by two‐photon microscopy (TPM) has become indispensable to the study of biology/medicine owing to its capability of imaging deep inside intact tissues. To make TPM a more‐versatile tool, a large variety of two‐photon probes are needed. Herein, we report a new two‐photon fluorescent probe (ANi2) that can be excited by 750 nm femtosecond pulses and detect Ni²⁺ ions in fresh fish organs at 90–175 μm depth without interference from the pH value or from other biologically relevant species through the use of TPM. TPM images of fish organs labeled with ANi2 revealed that Ni²⁺ ions accumulate in fish organs in the order: kidney > heart > gill ≥ liver. Moreover, a linear relationship was found between the two‐photon‐excited fluorescence (TPEF) and the inductively coupled plasma mass spectrometry intensities (ICP‐MS), thereby allowing the quantitative measurement of Ni²⁺ ions in live tissue.     

多重机制杂质吸附萃取净化-快速液相色谱-串联质谱法测定鱼组织中11种同化激素

建立了准确、灵敏的鱼组织中11种同化激素(勃地酮、雄烯二酮、诺龙、美雄酮、甲睾酮、睾酮、醋酸睾酮、群勃龙、丙酸睾酮、康力龙、氟甲睾酮)的多重机制杂质吸附萃取净化-快速液相色谱-串联质谱的分析方法。鱼组织均质样品经甲醇提取后,在上清液中加入一定量的C18固体吸附剂、中性氧化铝吸附剂和氨基功能化纳米吸附剂实现快速净化。采用Shim-Pack XR-ODSII色谱柱(100 mm×2.0 mm, 2.2 μm)分离,以乙腈(含0.1%甲酸)和水(含0.1%甲酸)为流动相进行梯度洗脱,电喷雾正离子多反应监测(MRM)模式下检测,外标法定量。结果表明,11种目标化合物在线性范围内具有良好的线性关系,相关系数大于0.999,其在鱼组织中的检出限(S/N＞3)为0.03～0.4 μg/kg,定量限(S/N＞10)为0.1～1.5 μg/kg,平均回收率为80.9%～98.1%,相对标准偏差(RSD)为5.2%～11.5%。该方法简便、快速、准确,可用于鱼组织中同化激素的定性、定量监测。