基于微流控技术调控生物大分子相分离

液-液相分离作为蛋白质等生物大分子组装成具有功能性的微液滴及无膜细胞器的基础,是生命体功能调控的一种极为普遍的方式,也是近年来新兴的前沿交叉领域。蛋白质相分离蕴含着微纳尺度流体在生物界面上复杂的力学机理,但是我们对相分离液滴成核生长的动力学及其精准调控的了解仍然有限。针对其中相分离微液滴形成的机制与调控的关键科学问题,本研究基于微流控技术,系统地研究了在不同实验条件下PGL-3蛋白质相分离的成核和生长动力学过程,实现了通过盐浓度以及蛋白质与固体表面之间的相互作用来控制相分离的生长过程和标度率。本研究提供了一个定量表征生物大分子相分离动态过程的体外系统,为深入理解生物大分子微液滴在复杂环境中的形成机制提供了研究基础

PHD2基因原核表达载体的构建及其在大肠埃希菌中的表达

目的构建PHD2基因原核表达载体pET43.1b(+)-PHD2,实现Nus-PHD2融合蛋白在大肠埃希菌中的可溶性表达。方法用Sac I酶切pET43.1b(+)制备线性化载体,设计与线性化载体两端具有至少15个同源序列的特异性引物,以真核重组质粒pCMV6-Entry-EGLNl为模板,PCR法扩增PHD2目的基因。采用In-Fusion技术构建原核表达载体pET-43.1b(+)-PHD2,并将其导入大肠埃希菌BL21 (DE3)中诱导表达。用SDS-PAGE和Western blot分析并鉴定表达出的融合蛋白。用Ni-NTA亲和层析法纯化目的蛋白。结果成功构建了PHD2原核表达载体;SDS-PAGE结果显示融合蛋白以可溶性形式表达;Western blot鉴定表明融合蛋白可以与PHD2单克隆抗体特异性结合。结论实现了 Nus-PHD2融合蛋白在大肠埃希菌中的可溶性表达,为PHD2生物学功能的研究奠定了基础

Sub-Nanogram Resolution Measurement of Inertial Mass and Density Using Magnetic-Field-Guided Bubble Microthruster

Artificial micro/nanomotors using active particles hold vast potential in applications such as drug delivery and microfabrication. However, upgrading them to micro/nanorobots capable of performing precise tasks with sophisticated functions remains challenging. Bubble microthruster (BMT) is introduced, a variation of the bubble-driven microrobot, which focuses the energy from a collapsing microbubble to create an inertial impact on nearby target microparticles. Utilizing ultra-high-speed imaging, the microparticle mass and density is determined with sub-nanogram resolution based on the relaxation time characterizing the microparticle's transient response. Master curves of the BMT method are shown to be dependent on the viscosity of the solution. The BMT, controlled by a gamepad with magnetic-field guidance, precisely manipulates target microparticles, including bioparticles. Validation involves measuring the polystyrene microparticle mass and hollow glass microsphere density, and assessing the mouse embryo mass densities. The BMT technique presents a promising chip-free, real-time, highly maneuverable strategy that integrates bubble microrobot-based manipulation with precise bioparticle mass and density detection, which can facilitate microscale bioparticle characterizations such as embryo growth monitoring. This work demonstrates a substantial progress of using swimming microrobots to perform precise tasks with sophisticated functions. This magnetic-field-guided bubble microthruster technique presents a promising chip-free, real-time, highly maneuverable strategy that integrates bubble microrobot-based manipulation with precise bioparticle mass and density detection with sub-nanogram resolution. This technique can facilitate microscale bioparticle characterizations such as embryo growth monitoring. imag

Catastrophic Degradation of InGaN/GaN Blue Laser Diodes

A study of catastrophic degradation of InGaN/GaN laser diodes (LDs) is presented. Local damage on the aged LD is identified with the reduction of the electron beam induced current intensity. A pipe-shaped defect is observed in the particular damaged region by using the transmission electron microscopy (TEM) and scanning TEM technique. Diffusion of the contact metal along the defect is enhanced by the local electric field and high temperature. Catastrophic degradation of the LD occurs due to burning of the local region