硫酸酯化葡甘聚糖凝胶颗粒的微观形貌及其吸附行为研究

制备了硫酸酯化魔芋葡甘聚糖凝胶颗粒血液低密度脂蛋白吸附剂，扫描电镜观察产物呈交联网状多孔结构。体外静态吸附实验表明：在37℃振荡吸附2h后，对总胆固醇（TC）、低密度脂蛋白及超低密度脂蛋白胆固醇（LDL＋VLDL-C）、高密度脂蛋白胆固醇（HDL-C）的吸附率分别为52．68％、54．76％、27．78％。通过吸附动力学曲线和吸附等温线分析，吸附剂对LDL＋VLDL-C的作用包括类似分子筛的吸附和电荷间静电相互作用两种方式。     

微沟槽图形结构对硅橡胶表面性能和细胞相容性的影响

目的 制作具有微沟槽图形的硅橡胶(silicone rubber,SR)表面改性材料,检测改性前后材料表面理化性质,初步评价细胞相容性.方法 利用具有微沟槽图形的方形母版,采用浇灌的方法成功制作表面具有微沟槽图形的硅橡胶改性材料,同时进行碳离子注入处理,并采用扫描电镜(scanning electron microscope,SEM)、原子力显微镜(atomic force microscope,AFM)、水接触角等技术测量改性前后硅橡胶的表面理化性质.通过细胞黏附实验、CCK-8细胞增殖实验以及Western blot等技术观察人真皮成纤维细胞的生长情况以及Talin、Zyxin蛋白的表达.结果 AFM观察到各组材料表面形貌出现明显的差异,微沟槽硅橡胶(patterned SR,P-SR)以及微沟槽-碳硅橡胶(patterned carbon ion implanted SR,PC-SR)均可在表面见微沟槽图形,而碳硅橡胶(carbon ion implanted SR,C-SR)出现不规则凸凹结构.水接触角显示材料进行微沟槽图形化处理后,可增加材料的水接触角.细胞黏附和增殖实验提示对材料进行微沟槽图形化处理后,细胞的黏附和增殖能力较C-SR降低,但两者差异无统计学意义.免疫荧光观察到人真皮成纤维细胞在P-SR和PC-SR组排列有序.Western blot检测细胞黏附相关蛋白Talin、Zyxin的表达在C-SR和PC-SR组高于SR组(P＜0.05).结论 微沟槽图形可影响硅橡胶的表面性能和细胞的增殖、排列等功能,对减轻包膜挛缩发生率起到积极作用.     

钛种植体表面微形态对成骨细胞生长影响的体外研究

目的:研究钛种植体表面微形态对成骨细胞生长的影响。方法:将原代培养的成骨细胞与三种不同表面处理的钛片(机械打磨组G、喷砂组SB、钛浆喷涂组TPS)共同培养,采用扫描电镜、MTT法、碱性磷酸酶活性(ALP)及骨钙素分泌(OC)的检测来观察不同表面微形态对成骨细胞粘附、增殖、分化的影响。结果:成骨细胞在不同钛片表面粘附生长,SB组、TPS组表面细胞呈分化表型。SB组、TPS组细胞增殖率高于G组(P <0 .0 5 )。第1d、5d、10d ,SB组、TPS组ALP的活性高于对照组(P <0 .0 5 ) ;G组第1d、3d、5dALP分泌与对照组比较,差异无显著性(P >0 .0 5 )。第3d、5d、10dSB组、TPS组OC分泌量与对照组相比有显著性差异(P <0 .0 5 )。结论:粗糙表面(SB组、TPS组)比光滑表面(G组)更有利于成骨细胞的粘附、增殖,能促进成骨细胞向成熟的表型分化。     

Irregularity skin index (ISI): a tool to evaluate skin surface texture

Background/aims: Irregularity of skin surface microtopography is difficult to evaluate in Euclidean geometry. Using a fast Fourier transform (FFT), it is possible to convert a space field into a frequency field and to obtain quantitative evaluation of this important feature of the skin. The aim of the present study was to test the applicability of a new parameter, derived from computer assisted FFT, to skin texture, in order to quantify its irregularity. This parameter has the additional advantage of being anisotropic.
Method: The study was conducted on 50 female volunteers. Skin replicas were performed on a healthy area that was not chronically photo-exposed. A new parameter, called "irregularity skin index" (ISI), was identified from FFT. The correlation with volunteers' age was calculated.
Results: ISI was calculated by FFT in two different directions (referred to the x and y axis of the diagram of the FFT and named, respectively, ISIωx and ISIωy). The irregularity skin indexes increased with age of the subjects, showing a correlation with age of r =0.47 (ISIωx) and r =0.51 (ISIωy).
Conclusion: By showing a relatively good correlation with age, ISI seems to be a promising parameter for the study of ageing skin.     

A Novel Simulation Method of Micro-Topography for Grinding Surface

A novel simulation method of microtopography for grinding surface was proposed in this paper. Based on the theory of wavelet analysis, multiscale decomposition of the measured topography was conducted. The topography was divided into high frequency band (HFB), theoretical frequency band (TFB), and low frequency band (LFB) by wavelet energy method. The high-frequency and the low-frequency topography were extracted to obtain the digital combination model. Combined with the digital combination model and the theoretical topography obtained by geometric simulation method, the simulation topography of grinding surface can be generated. Moreover, the roughness parameters of the measured topography and the simulation topography under different machining parameters were compared. The maximum relative error of Sa, Sq, Ssk and Sku were 1.79%, 2.24%, 4.69% and 4.73%, respectively, which verifies the feasibility and accuracy of the presented method.     

Analysis of the microtopography of the skin by silicone replicas after repeated exposure to actinic radiation at high altitudes.

We investigated the superficial microtopography of the normal skin of 11 volunteers (not exposed to sunlight during the last 4 months), before and after sun exposure for 5 days at high altitudes of 2900-4559 m. The experiments were carried out on Mount Rosa in Italy, and cutaneous replicas using silicone resin were taken every day after 7 h of sun exposure. Casts were taken from the forehead, glabella, dorsum nasi, radial side (protected with a cream SPF 9.72) and ulnar side of the back of the hands, the only areas not protected. A total of 422 replicas were metallized with gold-palladium and observed under Zeiss 940A scanning electron microscope. The images were elaborated and analysed on computer with appropriate software supplying geometrical features of cutaneous surface using parameters proposed by Takahashi (1994). A Student's test for paired series was used to analyse the differences before and after 1-5 days of exposure giving uniform and significant data compared with controls. Using cutaneous replicas we demonstrated that repeated exposure of skin to sunlight in a short time elicits temporary defence mechanisms with increased obstruction of cutaneous pores, deepening of primary cutaneous furrows and shallowing of part of the secondary furrows; the two latter alterations are the consequence of reactive oedema.     

Shape anisotropy-governed locomotion of surface microrollers on vessel-like microtopographies against physiological flows

Surface microrollers are promising microrobotic systems for controlled navigation in the circulatory system thanks to their fast speeds and decreased flow velocities at the vessel walls. While surface propulsion on the vessel walls helps minimize the effect of strong fluidic forces, three-dimensional (3D) surface microtopography, comparable to the size scale of a microrobot, due to cellular morphology and organization emerges as a major challenge. Here, we show that microroller shape anisotropy determines the surface locomotion capability of microrollers on vessel-like 3D surface microtopographies against physiological flow conditions. The isotropic (single, 8.5 µm diameter spherical particle) and anisotropic (doublet, two 4 µm diameter spherical particle chain) magnetic microrollers generated similar translational velocities on flat surfaces, whereas the isotropic microrollers failed to translate on most of the 3D-printed vessel-like microtopographies. The computational fluid dynamics analyses revealed larger flow fields generated around isotropic microrollers causing larger resistive forces near the microtopographies, in comparison to anisotropic microrollers, and impairing their translation. The superior surface-rolling capability of the anisotropic doublet microrollers on microtopographical surfaces against the fluid flow was further validated in a vessel-on-a-chip system mimicking microvasculature. The findings reported here establish the design principles of surface microrollers for robust locomotion on vessel walls against physiological flows.

Untethered cell-sized microrobots have emerged as a promising technology for next-generation biomedical applications, especially for minimally invasive cargo delivery at hard-to-reach regions inside the human body (1–5). Although the circulatory system appears as the ideal route for reaching all organs and tissues, harsh fluidic conditions in the blood vessels impair the motion of the swimming microrobots (6–8). On the other hand, surface-rolling magnetic microrobots inspired by leukocytes can evade the strong fluidic forces by taking advantage of decreased flow velocities at the vessel walls (9, 10). While surface-rolling microrobots can evade resistive fluidic effects, heterogeneous surface topography of vessel walls poses a crucial barrier for surface locomotion. The inner layer of the blood vessels, endothelium, is covered with elongated and packed endothelial cells that possess undulating topographic features in the size scale of a few microns (11). Topographical features on the endothelium mainly stem from the following: 1) topography of individual endothelial cells due to relatively rigid nucleus with a height of ∼2 to 5 µm (11, 12); 2) organization of endothelial cells in a monolayer depending on the biophysical and biochemical conditions, such as flow profile (13–15); and 3) abnormalities within the endothelium, such as protruding cells, due to abnormal physical conditions, including disturbed blood flow (16, 17) and atherosclerosis (18). Such topographic features could deteriorate and even completely stop the translational motion of rolling microrobots due to counterintuitive hydrodynamic effects. In our previous work (9), we observed nonmonotonic motion of spherical microrollers on endothelial cell layers against the physiological blood flow. Even though microrobot rolling over large obstacles (7, 19) and on periodic sharp ridges (20) was reported previously, the effects of physiological microtopographies and flow conditions found in blood vessels on the propulsion of cell-sized microrobots remain to be investigated.Here, we report the effects of vessel-like surface microtopographies on the propulsion of rolling microrobots with different shapes, under physiologically relevant flow conditions. Magnetically rotated single (isotropic) and doublet (anisotropic) microrollers are composed of a single 8.5 µm diameter and 2×4 µm diameter Janus microparticles, respectively, ensuring that both have similar height but different aspect ratio. Propulsion characteristics of both groups were similar on flat glass surfaces in static and flow conditions. While the doublet microrollers could translate over most of the three-dimensional (3D) microprinted topographical surfaces emulating the vascular surface topographies in static and dynamic flow conditions, the motion of single microrollers was almost completely impaired in both cases. The two-dimensional (2D) computational fluid dynamic (CFD) analyses revealed larger flow fields generated by the single microrollers in comparison to the doublet microrollers, causing resistive forces nearby microtopographical structures against the translation direction. We further investigated the motion of the microrollers on an endothelialized microfluidic “vessel-on-a-chip” system, in which the doublet microrollers outperformed the single microrollers. The experimental findings along with the numerical simulation results suggest the employment of rolling microrobots with an anisotropic shape, such as the doublet microrollers shown in Fig. 1, for efficient and robust surface locomotion against the flow within the circulatory system.Open in a separate windowFig. 1.Conceptual schematic illustration of the upstream motion capability of two different (single and doublet) microrollers on endothelium in a blood vessel. (A–C) The spherical (isotropic) microrollers are prone to fail on topographical features of the endothelial cells, whereas the doublet (anisotropic) microrollers could smoothly translate.     

Pedicle origin and intervertebral compartment in the lumbar and upper sacral spine

Summary The osseous boundaries of the intervertebral compartment are described. Measurements of the pedicles demonstrate that their configuration determines the shape of the intervertebral compartment. The pedicles originate in the upper lumbar spine (L 1 and L 2) in a vertical direction from the posterior aspects of the vertebral bodies. In the caudal lumbar spine (L 4 and L 5) the origin of the pedicles is more oblique and thereby moves much more laterally and ventrally. As a consequence the horizontal extension of the pedicles is increasing in the lower lumbar spine. In the upper lumbar region the intervertebral compartment corresponds more to a foramen, in the lower lumbar spine more to a canal. The resulting clinical relevance for the length of the intervertebral compartment and the nerve root course is discussed.     

Fabrication of Multiple Microscale Features on Polymer Surfaces for Applications in Tissue Engineering

One major difficulty in the creation of tissue-engineered constructs is the formation of a reproducible scaffold with a well-defined micro-architecture. In order to induce in vivo like cell geometry, complex patterns may be required. Such surfaces have been created by a combination of microfabrication and photolithography steps. These structures have been designed to be biologically, mechanically, and optically compatible with the study of cellular systems. Microtextured surfaces present new opportunities to engineer structures for more physiologically relevant biological studies. In addition, a temporary scaffold, allowing for cell in-growth, can be created by applying well-controlled microtopography to biodegradable polymers. Microfabrication techniques can be used to create complex patterns on the micron scale providing both scaffolding of tissue-engineered constructs as well as textured substrates for use in studies of biological phenomena such as cell-cell communication or cell-substrate interaction.