基于机器学习的低浓度多巴胺快速电化学检测方法研究

针对便携式恒电位仪精度较低、易受试验条件影响的问题,结合纳米材料修饰电极与机器学习算法,提出一种低浓度多巴胺(DA)电化学检测分析方法,以期在多个实验干扰因素存在的情况下实现DA的快速准确检测。利用计时电流法(CA)在玻碳电极(GCE)表面电沉积金纳米粒子制备AuNPs/GCE电极,采用循环伏安法(CV)验证其对DA的氧化还原具有良好的电催化活性。在不同底液pH和扫速下,基于AuNPs/GCE电极对不同浓度DA溶液进行重复性循环伏安检测,对检测数据进行峰高、峰电位、基线斜率、峰面积和起始氧化还原电位等重要特征参数的提取,并结合极端梯度提升树(XGBoost)和随机森林(RF)构建两阶段浓度预测模型。结果表明,对于不同pH和扫速干扰下的DA检测数据,相较于传统SVR模型,XGBoost-RF浓度预测模型的MAE、RMSE和MAPE%分别降低53.9%、39.7%和2.7%,RF预测模型的训练时间降低23%,预测准确度提升7%,预测值和真实值间的拟合度(R-Squared)为0.943。所提出方法有效降低了DA测定过程中不同实验干扰因素的影响,在提高检测精度的同时降低了实验的复杂度,对实现...     

植入式葡萄糖传感器国际研讨小组会

葡萄糖电催化传感器测量的原理在于:葡萄糖在覆盖一层薄膜的一种活化贵金属电极上直接的氧化作用。在限空扩散电流的范围内,所产生的氧化电流与膜上葡萄糖的浓度成比例关系。要准确确定其浓度,需通过三电极装置测定电极/膜系统的全阻抗,同时需考虑不同     

Tween20对联吡啶钌电化学发光的增敏作用

目的为进一步提高联吡啶钌电化学发光检测的灵敏度，研究了非离子表面活性剂Tween20对联吡啶钌电化学发光的增敏作用。方法对Tween20的浓度进行优化后，在最佳添加浓度0．1％的条件下，测试联吡啶钌的灵敏度、线性范围和稳定性。最后，探讨了Tween20对三丙胺电化学行为的影响。结果Tween20浓度为0．1％时，对联吡啶钌电化学发光的增敏作用最佳。在此浓度下，联吡啶钌的检测灵敏度提高了100倍，在浓度为5×10^-11～1×10^-7mol／L范围内与电化学发光强度呈良好的线性关系，且Tween20能促进三丙胺在电极表面的直接氧化并增强其氧化电流。结论Tween20对联吡啶钌的电化学发光具有较强的增敏作用。     

一种便携式酶电极血糖仪的研究

本研究介绍一种利用碳、银桨为导电材料的便携式高灵敏度酶电极血糖仪。酶电极一致性良好，采用二电极结构体系，用于检测以葡萄糖氧化酶催化血糖产生电化学反应形成的安培电流。仪器部分以单片微型计算机ADμC812为中央处理控制器，负责检测酶电极反应输出的安培电流，同时对信号进行放大、处理，最后在液晶显示器上显示。该机能很好地进行人体血糖值测试，测得的血糖值与大型生化分析仪器测得值的相关性较好。     

几种有发展前途厌氧菌的介绍

利用电极作为唯一的电子受体，乙酸氧化脱硫单胞菌、硫还原泥土杆茵和金属还原泥土杆菌通过氧化有机化合物收集生长所需能量。这不仅提供了一种可以从有机质中获取能量的方法，并且可用以有效提高有机污染物的生物整治效率。     

纯钛种植体表面微弧氧化涂层的生物相容性

背景：各种纯钛种植体表面微弧氧化涂层效果不尽相同。 目的：观察3种不同微弧氧化涂层种植体钛片对小鼠成骨细胞的细胞增殖、碱性磷酸酶活性和β1-integrin的基因表达水平的影响。 方法：采用国际常用小鼠成骨细胞系(MC3T3-E1),3种不同涂层钛片作为影响因素,纯钛作为对照,采用MTT法和电镜法观察细胞附着和细胞增殖,PNPP法测定碱性磷酸酶的活性,RT-PCR法检测β1-integrin在小鼠成骨细胞中的表达。 结果与结论：MTT值、碱性磷酸酶值、β1-integrin的基因表达水平和电镜观察均显示含钙、磷、镁、锌元素的二氧化钛涂层钛片生物相容性最好,含钙磷盐的二氧化钛涂层钛片次之,二氧化钛涂层钛片最差。小鼠成骨细胞在其多孔,含有钙、磷、镁、锌元素表面的黏附及增殖最优。     

HO/CO系统对血管内皮细胞保护作用的研究进展

血红素加氧酶是催化血红素氧化降解的起始酶和限速酶,HO催化血红素生成CO、胆绿素及铁,胆绿素及其代谢物胆红素均为强氧化剂.CO是一种新的气体信息分子和血管舒张因子.HO/CO系统对血管内皮细胞有强大的保护作用.     

聚乳酸/聚乙烯醇共混膜的亲水性与降解性能研究

采用流延法和溶剂蒸发技术,以聚乳酸(PLA)和聚乙烯醇(PVA)为原料,制备可降解PLA/PVA共混膜.研究PLA/PVA共混膜的吸湿、吸水性能及水降解性能,探索共混膜的水降解机制.结果表明,共混膜的吸湿率与吸水率随共混膜中PLA含量的增加而降低;共混膜在生理盐水中的降解过程是分步进行的,降解初期,PLA降解起主导作用,降解后期,PVA降解起主导作用.在PLA降解过程中,溶液的酸性具有催化降解效果,且PLA降解是从非晶区到晶区;PVA的引入,增加了共混膜的亲水性,并对PLA的结晶性能造成一定的破坏,加速PLA降解过程.因此,可通过调整PLA与PVA配比,在一定范围内对PLA/PVA共混膜的亲水性能与降解性能进行调控.     

微弧氧化陶瓷膜表面骨髓间充质干细胞生物相容性实验

目的观察微弧氧化（micro-arc,MAO）陶瓷膜表面骨髓间充质干细胞（mesenchymal stem cell,MSC）的黏附和增殖生长情况,通过MSC在三组不同表面处理材料表面的黏附和增殖情况评价微弧氧化陶瓷膜表面的生物相容性。方法贴壁法培养大鼠骨髓间充质干细胞,骨诱导培养后,做碱性磷酸酶染色和茜素红钙结节染色,鉴定其成骨潜能。取生长良好的第三代MSC,调整细胞密度为5×10^4/mL,接种到三组钛片表面。在接种细胞后第1、3、5、7天每组分别取出5枚钛片,一个做电镜扫描,另外4个细胞计数。观察MSC在不同材料表面的黏附增殖情况。电镜扫描MAO陶瓷膜表面形貌特征,EDX分析其表面主要元素含量。结果MSC具有良好的成骨特性,在MAO陶瓷膜表面的增殖优于光滑组和喷沙组。电镜下微弧氧化陶瓷膜表面有无数2～10m的微孔,并含有钙、磷成分。结论MAO陶瓷膜具有良好的生物相容性,大鼠骨髓间充质干细胞在其多孔,含有钙、磷元素表面的黏附及增殖均优于其它组。     

钌红染色在大鼠肺纤维化模型中的应用

钌红能与细胞表面及活性层下项的黏多糖成分反应,还原四氧化锇成锇黑,形成电子致密沉淀物,在电镜下以高电子致密物形式存在[1].本实验采用博莱霉素诱导大鼠肺间质纤维化模型,钌红染色,观察肺纤维化表面活性物质及胶原纤维超微结构的变化.由于钌红为大分子物质,它的溶解性和渗透性影响着此方法的稳定性和结果.本实验对钌红储备液的配制和钌红染色方法进行了改进,提高了钌红溶液的溶解度和渗透性,获得较为稳定的结果.     

Protein adsorption and peroxidation of rat retinas under stimulation of a neural probe coated with polyaniline

For the purpose of investigating the potential use of conducting polymers, i.e. polyaniline (PANi), as electrode coating material for improving the function of neural probes, a PANi-coated platinum (Pt) electrode was prepared by the in situ polymerization method. Protein adsorption was observed by atomic force microscopy/scanning electron microscopy and sodium dodecyl sulfate polyacrylamide gel electrophoresis, as well as quantification. Peroxidation of rat retinas was evaluated by determination of conjugated dienes and PLOOH, which were quantified by UV–visible spectrophotometer and high-performance liquid chromatography. The stability of PANi coating for 6 months was also estimated with an in vitro electrical stimulation system. This revealed that: (1) PANi with regular and compact nanoparticles 20–40 nm in diameter was successfully polymerized on the uncoated platinum electrode surface; (2) the PANi-coated Pt electrode adsorbed fewer retinal fragments and induced less peroxidation than the uncoated platinum electrode; (3) in contrast to the uncoated platinum electrode, the PANi-coated Pt electrode surface tended to aggregate retinal fragments rather than spread them, which may help to reduce inflammation and scar formation in long-term implantation; (4) the PANi coating exhibited excellent properties in terms of the intactness and the stable nanoparticle morphology after 6 months’ electrical stimulation, while corrosion occurred on the uncoated platinum electrode after 1 month.     

Some studies related to electricity generation from biological fuel cells and galvanic cells,in vitro andin vivo

A biological fuel cell such as an oxygen/glucose cell has been considered to be an ideal power source for implantable cardiac pacemakers and similar devices. This study is mainly concerned with the development of a single oxygen/glucose cell, which can be implanted inside the body fluids with the simultaneous presence of oxidant and fuel(s). Present results ofin vitro experiments with a single oxygen/glucose cell consisting of a platinum black on platinum-mesh electrode (cathode) and a platinum black on porous-graphite electrode (anode) have shown that cell performance was markedly increased after glucose addition. Half-cell testings by means of a potentiostat coupled to a linear sweep generator also demonstrated that the anode current of a platinised graphite electrode after glucose was over 3 mA/cm². It was also found that a steady and continuous power output of 20 μW/cm² could be generated from the above oxygen/glucose cell. When the cell was testedin vivo in the rat. the continuous power output was steady at 3·3 μW/cm². The present study also investigated the possibility of generating electricity from an oxygen concentration cell and an oxygen/hydrogen cell. It was concluded that a platinum black on porous graphite electrode offers promise as a specific electrode for glucose oxidation. An oxygen/hydrogen cell could also provide a long termin vivo power supply provided the Pd-H electrode is properly encapsulated. The significance of the present study in relation to the development of biological power sources is discussed, and the importance of fundamental investigation for the development of a specific electrode is emphasised.     

Immobilized enzyme electrodes for the potentiometric measurement of glucose concentration: immobilization techniques and materials.

Glucose oxidase, catalase, and bovine serum albumin were co-immobilized with glutaraldehyde around a platinum screen or around a single platinum-iridium wire. The potential difference between this dual enzyme electrode and a Ag/AgCL reference electrode was proportional to the logarithm of the glucose concentration over the range from 10 to about 150 mg glucose per 100 ml in buffered solution at pH 7.4 and 37 degrees C. The enzyme electrode responded in serum only if coated with a semipermeable film, such as cellulose acetate, to exclude serum macromolecules. The potentiometric results were similar to those obtained with the two enzymes co-immobilized in polyacrylamide gel around a platinum screen or with only one of the enzymes, glucose oxidase, covalently coupled to a platinum screen. The results so far suggest that glucose for development of a continuous in vivo glucose sensor.     

纳米Ag/TiO2涂层托槽的研制及力学性能

背景：前期实验发现纳米Ag可以原子态沉积于纳米TiO₂涂层表面,增强涂层的可见光催化抗菌性能。 目的：研制纳米Ag/TiO₂涂层托槽,并分析其力学性能。 方法：使用溶胶-凝胶法制备不同退火温度下的纳米Ag/TiO₂涂层托槽,在扫描电镜下观察纳米Ag/TiO₂涂层托槽的表面形貌;测量普通金属托槽、纳米TiO₂涂层托槽和各组纳米Ag/TiO₂涂层托槽的表面粗糙度;采用划痕实验法检测纳米TiO₂涂层和各组纳米Ag/TiO₂涂层与基体托槽的结合强度。 结果与结论：纳米Ag/TiO₂涂层厚度约120 nm,为具有严整组织结构的纳米颗粒膜,表面平整、光滑、光洁度高,并可见Ag颗粒沉积在涂层上。纳米TiO₂涂层托槽和各组纳米Ag/TiO₂涂层托槽表面粗糙度与普通商业用托槽差别无差异(P > 0.05);纳米TiO₂涂层、120,200,300 ℃退火温度纳米Ag/TiO₂涂层与基体托槽的结合强度分别为1.18,1.16,1.12,1.26 kg。表明研制的纳米Ag/TiO₂涂层托槽具有良好的力学性能,可以满足口腔正畸临床需要。     

Metallocene Catalyzed Polymerization of Ethylene in the Presence of Graphite, 1. Synthesis and Characterization of the Composites

Polyethylene/graphite composites have been prepared by two different methods. In a first approach, the ethylene polymerization has been catalyzed by metallocene in the presence of neat graphite particles (NGC composites). A second series of composites (TGC) has been prepared by the polymerization‐filling technique, which requires that the metallocene/methylalumoxane catalyst is fixed onto the graphite surface prior to the ethylene polymerization. The two series of composites exhibit significantly different morphology and thermal properties. The filler distribution is very heterogeneous in the NGC series. The morphology changes from an intimate mixture of PE and filler particles at low graphite content to graphite covered by patches of PE at high filler loading. The graphite distribution is much more homogeneous in the TGC samples, and the morphology consists of particles covered by a layer of PE in the whole composition range. Differences in the thermal properties are discussed in relation to the morphology.     

Pt/TiO2 brain biocompatible nanoparticles: GBM treatment using the C6 model in Wistar rats

In the present work we synthesized inorganic oxide nanoparticle carriers of platinum compounds and tested their therapeutic effect on animal models in which C6 glioma cells have been inoculated. TiO(2)-containing Pt(NH(3))(4)Cl(2) complexes were synthesized using sol-gel methods. The platinum species are chemically bonded to the TiO(2) carrier, as shown by Fourier transform infrared spectroscopy of probe molecules. Treatment with TiO(2)-Pt nanoparticles reduces tumour growth rate by up to 56%, showing that a synergistic effect exists between the TiO(2) carrier and the platinum drug.     

Goldmag-based enzyme-linked immunosorbent assay for determination of α-lactalbumin in milk

In this work, a goldmag-based enzyme-linked immunosorbent assay was developed for determination of α-lactalbumin (α-LA) in milk. The magnetic nanoparticle functionalized with polyetherimide was synthesized by one-pot method and coated with two layers of gold nanoparticles on the surface to synthesize goldmag nanoparticles. Anti-α-LA monoclonal antibody, prepared by hybridoma cell lines via cell fusion, was then bound to this goldmag nanoparticle to develop a capture nanoprobe. The results showed that this developed immunoassay had a good linear range of 2.33–127.1?ng/mL with IC₅₀ of 17.2?ng/mL. Besides, recovery rates for α-LA in four commercial milks were from 86.7% to 109.8%. The coefficients of variation in intra-assay and inter-assay were 3.9–6.8% and 5.5–9.8%, separately, which could meet the requirements to quantify α-LA content in milk. This goldmag-based immunoassay might have considerable potentials in the detection of food allergies.     

美斯地浓聚乳酸载药纳米粒的制备及体外释放

背景：美斯地浓临床常用于治疗重症肌无力,但其水溶性较强,半衰期短,生物利用度低,给药频率高,患者依从性差,因此提高其缓释作用对临床应用有重要意义。 目的：制备美斯地浓聚乳酸纳米粒,并考察其体外释放性能。 方法：以聚乳酸为载药材料,采用复乳液中干燥法制备美斯地浓聚乳酸纳米粒,运用单因素实验设计优化处方,动态透析法进行体外药物释放实验。 结果与结论：确定以二氯甲烷作为油相制备纳米粒,内水相与油相的比例1∶10,聚乳酸浓度6%,外水相聚乙烯醇浓度3%,美斯地浓投药量40 mg为最佳制备工艺,此条件制备的药物纳米粒包封率和载药率分别为(67.59±1.46)%和(4.31±0.17)%。美斯地浓聚乳酸纳米粒的平均粒径为937 nm,圆球形,表面光滑,未观察到粘连现象。与美斯地浓游离药物相比,美斯地浓聚乳酸纳米粒存在突释现象,之后呈现缓慢释放特性,72 h释放量为57.03%,提示成功制备美斯地浓聚乳酸纳米粒,具有缓释效应。     

Development of a platinized platinum/iridium electrode for use in vitro

Silver/silver chloride (Ag/AgCl) electrodes possess excellent electrical properties for measuring the electrical activity of gastrointestinal smooth muscle but exert toxic effects on this tissue in vitro. We thus developed a platinum electrode for use in vitro, the construction of these electrodes relying upon the formation of a glass-platinum/iridium seal. The platinum/iridium (Pt/Ir) electrodes were platinized using a current density of 0.45 mA mm⁻². The electrode impedance at 0.01 Hz showed a minimum with platinization current-time products greater than 500 mA s mm⁻². However, deposits in excess of 600 mA s mm⁻² were readily removed by mechanical abrasion and proved unsatisfactory. Optimal platinization was obtained with a deposit of platinum-black corresponding to a current-time product of 550 mA s mm⁻². Optimally-platinized electrodes (geometric surface area 0.11 mm²) had a stable and reproducible potential with a drift of less than 1 μV min⁻¹ and a lower impedance than optimally chlorided silver electrodes (geometric surface area 0.46 mm²) at frequencies higher than 0.25 Hz. The platinized Pt/Ir electrodes were used to record the electrical activity of gastrointestinal smooth muscle in vitro.     

Substrate dependent stability of conducting polymer coatings on medical electrodes

Conducting polymer (CP) coatings on medical electrodes have the potential to provide superior performance when compared to conventional metallic electrodes, but their stability is strongly dependant on the substrate properties. The aim of this study was to examine the effect of laser roughening of underlying platinum (Pt) electrode surfaces on the mechanical, electrical and biological performance of CP coatings. In addition, the impact of dopant type on electrical performance and stability was assessed. The CP poly(ethylene dioxythiophene) (PEDOT) was coated on Pt microelectrode arrays, with three conventional dopant ions. The in?vitro electrical characteristics were assessed by cyclic voltammetry and biphasic stimulation. Results showed that laser roughening of the underlying substrate did not affect the charge injection limit of the coated material, but significantly improved the passive stability and chronic stimulation lifetime without failure of the coating. Accelerated material ageing and long-term biphasic stimulus studies determined that some PEDOT variants experienced delamination within as little as 10 days when the underlying Pt was smooth, but laser roughening to produce a surface index of 2.5 improved stability, such that more than 1.3 billion stimulation cycles could be applied without evidence of failure. PEDOT doped with paratoluene sulfonate (PEDOT/pTS) was found to be the most stable CP on roughened Pt, and presented a surface topography which encouraged neural cell attachment.