Influence of root resistivity on plant water uptake mechanism,Part II: analytical solutions for low/moderate soil-root conductivity ratio

A one-dimensional approximate analytical model, which preserves the main features of soil-crop-atmospheric hydrodynamics, has been suggested for plant roots of low soil-root conductivity ratio (SRCR). The proposed approach involves physically based concepts, such as mass balance equation, Darcy’s law, and related water uptake and plant transpiration functions. Two main assumptions have been made to derive the analytical solution: (1) gravitational flow is adopted and (2) the uniform soil moisture distribution within the root water activity zone is supposed. The mass balance equation in its integral form is solved by the method of characteristics. This leads to the two functional equations for soil pressure head and root potential, which can be solved simultaneously by using common software. The model has been further verified against the numerical one. The model represents a reasonable compromise between the complicated mechanism of unsaturated water flow with root water uptake (RWU) and still insufficient knowledge of the soil-plant-atmospheric continuum. It is able to account for temporal fluctuations in root activity zone and provides a relatively simple algorithm for investigation of RWU-mechanism. Besides the theoretical and applicative importance, this flow model yields water and velocity distributions within soil profile, and, thereby, constitutes a preliminary step toward solution of contaminant transport problems in vadose zone. Deceased     

纳米生物无机界面的构筑与循环肿瘤细胞分离

纳米生物无机界面的研究是无机化学学科新兴的前沿领域之一。纳米结构的无机材料在仿生界面、细胞界面、生物检测界面等领域扮演着越来越重要的角色。近几年来,无机纳米结构被尝试用于痕量循环肿瘤细胞(Circulating Tumor Cells,CTCs)分离的基础探索研究中,并展现出非常吸引人的应用前景。痕量CTCs的高效分离对于癌症早期检测、术后监测及生物学研究等具有重要的意义。本文主要综述纳米生物无机界面在CTCs分离中的应用,详细介绍其发展现状,并对未来做一展望。     

Where is the road to bio-water-saving for the globe?

The First International Conference on the Theory and Practices in Bio-water-saving (ICTPB) was held from May 21 to 25, 2006 in Beijing, China. This indicated that the work related to this hot topic on the globe has been paid more attention to. Most progress in this field has been presented from near 300 participating people worldwide, who were meeting together to discuss about the theory and practices of water-saving biology and how to serve global agricultural and ecological sustainable development. The work related to bio-water-saving has been involved in different scales and soil–plant root biointerfaces. On the basis of this background and in combination with the work from our laboratory and the center, we provided some ideas for global bio-water-saving in this paper, sharing the achievement in this field and advocating true bio-water-saving for the world and promoting the pace of global bio-water-saving.     

Multifunctional Surface Modification: Facile and Flexible Reactivity toward a Precisely Controlled Biointerface

A multicomponent functional polymer is synthesized to support specific reactivity for successful conjugation with the vast array of functionality present in biological systems and the flexibility to conjugate biomolecules without requiring additional modification to install a terminal functional group. The multifunctional surface is realized using a novel coating composed of distinct N‐hydroxysuccinimide (NHS) ester and benzoyl functionalities, which can provide accessibility to both the NHS ester‐amine coupling reaction and the photochemically induced benzophenone crosslinking reaction, respectively. In addition, the multifunctional polymer is fabricated and transformed to form nanoscale colloids through the solvent displacement of a water/DMF system due to solubility characteristics of the resulting polymer with high polarity. A facile and efficient fabrication approach using the multifunctional nanocolloid is thus demonstrated to create a drug carrier by installing paclitaxel and folic acid for targeted cancer therapy.

     

纳米生物无机界面的构筑与循环肿瘤细胞分离

纳米生物无机界面的研究是无机化学学科新兴的前沿领域之一。纳米结构的无机材料在仿生界面、细胞界面、生物检测界面等领域扮演着越来越重要的角色。近几年来, 无机纳米结构被尝试用于痕量循环肿瘤细胞(Circulating Tumor Cells, CTCs)分离的基础探索研究中, 并展现出非常吸引人的应用前景。痕量CTCs的高效分离对于癌症早期检测、术后监测及生物学研究等具有重要的意义。本文主要综述纳米生物无机界面在CTCs分离中的应用, 详细介绍其发展现状, 并对未来做一展望。     

基于磷脂膜的界面相互作用研究

磷脂是一类非常重要的生物分子,它是细胞膜的主要组成部分,同时也在诸多生命活动（如细胞激活、代谢维持和激素分泌等）中发挥着不可替代的作用。磷脂种类繁多,且具有自组装能力强、生物相容性好、无细胞毒性、易于获得等一系列优点。作为一种最典型的界面材料,磷脂膜特殊的双层结构及出色的生物学性能引起了科研人员的广泛关注,其能够模拟生物膜结构,有助于研究界面上的分子特征及作用行为。此外,磷脂可被用作生物医学材料,改性磷脂以及磷脂与纳米颗粒的复合物在肿瘤成像技术、药物靶向递送系统等方面具有良好的发展前景,显著促进了新型生物材料的开发与进步。本文先归纳了磷脂的分类,并比较了磷脂在不同基底的吸附行为;之后重点分析了磷脂膜界面的选择性识别功能以及与多肽、酶、蛋白质等生物分子之间的相互作用;最后对基于磷脂膜的生物材料在生物传感、药物研究和成像技术中的应用作出了展望。     

Catch and release cell sorting: electrochemical desorption of T-cells from antibody-modified microelectrodes

The development of integrated microsystems capable of interrogation, characterization and sorting of mammalian cells is highly significant for further advancement of point-of-care diagnostics and drug discovery fields. The present study sought to design a novel strategy for releasing antibody-bound cells through electrochemical disruption of the underlying antibody (Ab) layer. A microsystem for selective capture and release of cells consisted of an array of individually addressable gold microelectrodes fabricated on a glass substrate. Poly(ethylene glycol) (PEG) hydrogel photolithography was employed to make the glass regions non-fouling, thus, ensuring selective localization of proteins and cells on the microelectrodes. The gold surfaces were decorated with anti-CD4 Ab molecules using standard alkanethiol self-assembly and carbodiimide coupling approaches. The Ab-functionalized electrodes selectively captured model T-lymphocytes (Molt-3 cells) expressing CD4 antigen while minimal cell adhesion was observed on PEG hydrogel-modified glass substrates. Importantly, application of a reductive potential (-1.2V vs. Ag/AgCl reference electrode) resulted in release of surface-bound T-cells from the electrode surface. Cyclic voltammetry and fluorescence microscopy were employed to verify that the detachment of captured T-cells was indeed due to the electrochemical disruption of the underlying alkanethiol-Ab layer. In the future, the cell sorting approach described here may be combined with microfluidic delivery to enable Ab-mediated capture of T-lymphocytes or other cell types followed by release of select cells for downstream gene expression studies or re-cultivation.     

Chiral polymer-based biointerface materials

Chirality is a unique phenomenon in nature. Chiral interactions play an important role in biological and physiological processes, which provides much inspiration for scientists to develop chiral materials. As a breakthrough from traditional materials, biointerface materials based on chiral polymers have attracted increasing interest over the past few years. Such materials elegantly combine the advantages of chiral surfaces and traditional polymers, and provide a novel solution not only for the investigation of chiral interaction mechanisms but also for the design of biomaterials with diverse applications, such as in tissue engineering and biocompatible materials, bioregulation, chiral separation and chiral sensors. Herein, we summarize recent advances in the study of chiral effects and applications of chiral polymer-based biointerface materials, and also present some challenges and perspectives.