电沉积石墨烯的非共价功能化用于SPR核酸传感的协同增敏

研究了一种高效的表面等离子共振(SPR)基DNA分析方法,利用非共价功能化的石墨烯纳米片作为基底,并以酶催化诱导的聚合作为质量中继。该策略有多方面的目标:首先,通过原位优化的石墨烯薄膜的电生成,该过程由原子力显微拓扑图表征,来敏化总体的SPR输出;其次,用于调制镍离子螯合的胺基三乙酸支架,其吸附在石墨烯支撑的苝基衍生物表面,上端生物素化捕获探针可以自组装,并保有一定的方向;最后,通过辣根过氧化物酶标记的报告单元,实时地将苯胺添加剂转化为聚苯胺沉淀,以协同实现信号的放大。运用上述配置,获得了一个对特异性DNA靶标精确且可重现传感的平台,检测下限达到飞摩尔水平,从而展现了以二维纳米材料为独特SPR基础设施的有益探索和开发。该"自下而上"的建构、与置顶"自上而下"的重量反应器,极有可能拓展并移植用于蛋白质的定量。     

石墨烯增敏的SPR技术应用于HIV1 p24抗原的检测

目的:建立石墨烯增敏的表面等离子体共振技术(Surface Plasmon Resonance,SPR)用于检测HIV1 p24,为HIV感染者的早期快速筛查提供一种检测方法.方法:石墨烯通过静电连接在采用聚乙二醇高分子处理的SPR芯片表面,HIV1 p24特异性抗体通过石墨烯表面的羧基官能团和HIV1 p24抗体表面...     

各向异性粒子的计算机设计及其组装结构的模拟

通过对各向异性粒子表面“补丁”的类型、数量、位置等因素进行设计和调控,研究了各向异性粒子的定向可控自组装。对表面修饰的球、棒等粒子的自组装行为模拟表明,其组装结构取决于粒子本身的各向异性及表面“补丁”的性质,并且可以通过合理设计得到目标微结构。如果使用动态共价键将分子链接枝到粒子表面,可以得到具有动态响应性质及有序组装结构的“智能”材料。另外,基于生物分子螺旋结构的仿生设计,在粒子表面设计修饰上特定的互补的“补丁”对,得到了可调整螺距和半径的螺旋组装结构,可用于制备具有不同催化或光学活性的手性材料。这些研究表明,通过合理设计粒子表面性质,可以制备出具有特定目标结构和性质的粒子组装结构,极大地拓宽了纳米粒子、胶体粒子在生物、医药和光电器件材料等方面的应用范围。     

氧化石墨烯的可控还原及表征

采用Hummers修正法制备氧化石墨烯(GO),用壳聚糖(CS)作为“绿色”无毒还原剂,以反应温度和反应时间来控制氧化石墨烯的还原程度。用红外光谱、紫外可见吸收光谱、拉曼光谱和X射线衍射等多种表征手段研究不同还原程度的还原氧化石墨烯的结构与性能。结果表明,改变温度不能有效地控制氧化石墨烯的还原程度;在50℃低温环境下,控制反应时间可以得到不同还原程度的还原氧化石墨烯,为进一步研究不同还原程度还原氧化石墨烯的非线性光学性质奠定了基础。     

选钼回水中铝离子对辉钼矿可浮性的影响机制

通过辉钼矿浮选实验、Zeta电位测试、Al3+溶液化学分析及X射线光电子能谱分析(XPS),研究了选钼回水中的Al3+对辉钼矿可浮性的影响及其作用机制. 结果表明,铝离子会恶化辉钼矿的浮选指标,并导致其表面Zeta电位显著偏移,表明辉钼矿表面有Al3+吸附;Al3+在溶液中主要以铝离子、羟基铝离子、氢氧化铝沉淀形式存在,后两者具有极强的极性,能吸附在辉钼矿活泼的“棱”上,铝离子与辉钼矿“棱”氧化生成的MoO42?反应生成钼酸铝沉淀;由于辉钼矿“棱”的面积比“面”的面积小很多,而铝离子主要吸附在“棱”上,因此铝元素含量不多,但其确实能吸附在辉钼矿表面,且既有物理吸附也有化学吸附.     

二维结构石墨烯基生物传感器的研究进展

石墨烯是严格意义上的二维材料,具有出色的光学、力学、电学和热学性能,石墨烯基材料也已广泛应用于不同领域。综述了基于石墨烯二维结构的电化学生物传感器的研究进展,主要包括酶传感器、免疫传感器、DNA传感器,同时探讨了石墨烯基材料制备和发展过程中的挑战。     

多孔石墨烯基酞菁铁复合物的制备及其电催化氧还原性能研究

利用溶剂热法制备多孔石墨烯,然后超声处理将酞菁铁修饰在多孔石墨烯表面,制备出多孔石墨烯基酞菁铁复合物用于碱性介质氧还原。利用循环伏安法和线性扫描伏安法考察该复合物的催化氧还原的能力,结果显示:多孔石墨烯基酞菁铁复合物修饰电极比多孔石墨烯修饰电极表现出更正的还原电位,具有更高的催化活性。     

一种用于合成乙二醇的固体催化剂及其制备方法

<正>常州大学开发出一种用于合成乙二醇的固体催化剂及其制备方法,该方法以氧化石墨烯和卤代烷基胺为原料,通过共价键的方式将胺基嫁接到氧化石墨烯表面,从而获得一种高效的固体催化剂。该方法操作简单,得到的固体催化剂在反应后经过简单处理即可继续循环利用,寿命长,无污染,大大降低了生产成本。将本发明制备的催化剂用于碳酸乙烯酯水解合成乙     

固定化酶提取大蒜多糖的研究

以甲基丙烯酸缩水甘油酯为功能单体,以二甲基丙烯酸乙二醇酯为交联剂,通过悬浮聚合合成了环氧基树脂载体。将合成的环氧基载体用于固定菠萝蛋白酶,并利用该固定化酶提取大蒜多糖。结果表明:环氧基载体对酶的平均固定化量可达m(蛋白质):m(树脂)=0.0501,固定化酶对大蒜多糖的提取效率比游离酶提高了1.03%。     

石墨烯/环氧树脂对碱激发砂浆基本力学性能的影响

通过水热还原法将利用Hummers法制备得到的氧化石墨烯制备成石墨烯,通过透射电镜观测石墨烯的形貌;利用占环氧树脂0.05%,0.10%和0.20%质量分数的石墨烯改性制备得到石墨烯/环氧树脂复合材料,并对石墨烯/环氧树脂复合材料的拉伸性能以及拉伸断面进行扫描电镜分析,选择拉伸性能最好的石墨烯/环氧树脂复合材料以3%,6%和9%质量分数的掺量用于矿渣粉煤灰基碱激发材料中,利用抗折抗压性能以及扫描电镜微观结构分析石墨烯/环氧树脂复合材料对矿渣粉煤灰基碱激发砂浆的性能影响。实验发现,石墨烯掺量为0.10%的石墨烯/环氧树脂复合材料的拉伸性能最好,石墨烯/环氧树脂复合材料掺量为3%,6%和9%的矿渣粉煤灰基碱激发砂浆的抗折性能分别提高了13.1%,9.3%和18.6%,而复合材料对砂浆的抗压性能影响不大。     

Effect of Molybdenum Disulfide Layer on Surface Plasmon Resonance Biosensor for the Detection of Bacteria

In this study, a molybdenum disulfide (MoS₂) based surface plasmon resonance (SPR) biosensor is proposed. The reflectance curves for the proposed SPR biosensor are analyzed and compared with the graphene based and the conventional SPR biosensors. It is observed that the performance parameters of the proposed biosensor- sensitivity, detection accuracy, and the quality factor are enhanced by the utilization of the adsorption property of MoS₂ for monolayer and bi-layer MoS₂. Also, the effect of increasing the number of layers of MoS₂ on the reflectance curve is analyzed and compared.     

Optical Biosensor Based on Graphene and Its Derivatives for Detecting Biomolecules

Graphene and its derivatives show great potential for biosensing due to their extraordinary optical, electrical and physical properties. In particular, graphene and its derivatives have excellent optical properties such as broadband and tunable absorption, fluorescence bursts, and strong polarization-related effects. Optical biosensors based on graphene and its derivatives make nondestructive detection of biomolecules possible. The focus of this paper is to review the preparation of graphene and its derivatives, as well as recent advances in optical biosensors based on graphene and its derivatives. The working principle of face plasmon resonance (SPR), surface-enhanced Raman spectroscopy (SERS), fluorescence resonance energy transfer (FRET) and colorimetric sensors are summarized, and the advantages and disadvantages of graphene and its derivatives applicable to various types of sensors are analyzed, and the methods of surface functionalization of graphene and its derivatives are introduced; these optical biosensors can be used for the detection of a range of biomolecules such as single cells, cellular secretions, proteins, nucleic acids, and antigen-antibodies; these new high-performance optical sensors are capable of detecting changes in surface structure and biomolecular interactions with the advantages of ultra-fast detection, high sensitivity, label-free, specific recognition, and the ability to respond in real-time. Problems in the current stage of application are discussed, as well as future prospects for graphene and its biosensors. Achieving the applicability, reusability and low cost of novel optical biosensors for a variety of complex environments and achieving scale-up production, which still faces serious challenges.     

Graphene oxide-based SPR biosensor chip for immunoassay applications

This work develops a highly sensitive immunoassay sensor for use in graphene oxide sheet (GOS)-based surface plasmon resonance (SPR) chips. This sensing film, which is formed by chemically modifying a GOS surface, has covalent bonds that strongly interact with the bovine serum albumin (BSA), explaining why it has a higher sensitivity. This GOS film-based SPR chip has a BSA concentration detection limit that is 100 times higher than that of the conventional Au-film-based sensor. The affinity constants (K_A) on the GOS film-based SPR chip and the conventional SPR chip for 100 μg/ml BSA are 80.82 × 10⁶ M^-1 and 15.67 × 10⁶ M^-1, respectively. Therefore, the affinity constant of the GOS film-based SPR chip is 5.2 times higher than that of the conventional chip. With respect to the protein-protein interaction, the SPR sensor capability to detect angle changes at a low concentration anti-BSA of 75.75 nM on the GOS film-based SPR chip and the conventional SPR chip is 36.1867 and 26.1759 mdeg, respectively. At a high concentration, anti-BSA of 378.78 nM on the GOS film-based SPR chip and the conventional SPR chip reveals two times increases in the SPR angle shift. Above results demonstrate that the GOS film is promising for highly sensitive clinical diagnostic applications.     

Function of Graphene Oxide as the “Nanoquencher” for Hg2+ Detection Using an Exonuclease I-Assisted Biosensor

Graphene oxide is well known for its excellent fluorescence quenching ability. In this study, positively charged graphene oxide (pGO25000) was developed as a fluorescence quencher that is water-soluble and synthesized by grafting polyetherimide onto graphene oxide nanosheets by a carbodiimide reaction. Compared to graphene oxide, the fluorescence quenching ability of pGO25000 is significantly improved by the increase in the affinity between pGO25000 and the DNA strand, which is introduced by the additional electrostatic interaction. The FAM-labeled single-stranded DNA probe can be almost completely quenched at concentrations of pGO25000 as low as 0.1 μg/mL. A simple and novel FAM-labeled single-stranded DNA sensor was designed for Hg²⁺ detection to take advantage of exonuclease I-triggered single-stranded DNA hydrolysis, and pGO25000 acted as a fluorescence quencher. The FAM-labeled single-stranded DNA probe is present as a hairpin structure by the formation of T–Hg²⁺–T when Hg²⁺ is present, and no fluorescence is observed. It is digested by exonuclease I without Hg²⁺, and fluorescence is recovered. The fluorescence intensity of the proposed biosensor was positively correlated with the Hg²⁺ concentration in the range of 0–250 nM (R² = 0.9955), with a seasonable limit of detection (3σ) cal. 3.93 nM. It was successfully applied to real samples of pond water for Hg²⁺ detection, obtaining a recovery rate from 99.6% to 101.1%.     

Surface plasmon resonance-induced visible light photocatalytic reduction of graphene oxide: using Ag nanoparticles as a plasmonic photocatalyst

The present communication reports on the first preparation of reduced graphene oxide (rGO) via surface plasmon resonance (SPR)-induced visible light photocatalytic reduction of GO with the use of Ag nanoparticles (AgNPs) as a plasmonic photocatalyst in the presence of an electron donor (ED).     

A novel electrochemical DNA biosensor based on graphene and polyaniline nanowires

A novel DNA biosensor based on oxidized graphene and polyaniline nanowires (PANIws) modified glassy carbon electrode was developed. The resulting graphene/PANIw layers exhibited good DPV current response for the complementary DNA sequences. The good electron transfer activity might be attributed to the effect of graphene and PANIw. Graphene and PANIw nanolayers film with highly conductive and biocompatible nanostructure were characterized by scanning electron microscopy (SEM), cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS). The immobilization of the probe DNA on the surface of electrode was largely improved due to the unique synergetic effect of graphene and PANIw. Under optimum conditions, the biosensor exhibited a fast amperometric response, high sensitivity and good storage stability for monitoring DNA. The current response of the sensor increases linearly with the concentration of target from 2.12 × 10⁻⁶ to 2.12 × 10⁻¹² mol l⁻¹ with a relative coefficient of 0.9938. The detection limit (3σ) is 3.25 × 10⁻¹³ mol l⁻¹. The results indicate that this modified electrode has potential application in sensitive and selective DNA detection.     

Raman characterization and UV optical absorption studies of surface plasmon resonance in multishell nanographite

Nanographite (NG) particles were produced by annealing of superpurified detonation nanodiamonds (grain size ~ 5 nm) at 1600 °C. The aim of this research was to provide Raman characterization of nanographites obtained and to investigate characteristic features of UV optical absorption in NG suspensions caused by the excitation of surface plasmon resonance (SPR) and its dependence on disorder and defectiveness of graphene shells during their transformation. The 1-st and 2-nd order Raman spectra of the NG samples excited at 514 nm were analyzed. Two different approaches applied for evaluation of the in-plane NG crystallite sizes by using the D- and G-band intensities ratio gave quite different results (~ 3.5 nm and ~ 5.5 nm) reflecting, most likely, a complicated NG structure. The changes in both intensity and position of SPR absorption peak for water suspension of NG particles may originate in structural imperfections and/or changes in aggregation of NG particles.     

Gold nanoparticles/single-stranded DNA-reduced graphene oxide nanocomposites based electrochemical biosensor for highly sensitive detection of cholesterol

High density and uniform distribution of the gold nanoparticles functionalized single-stranded DNA modified reduced graphene oxide nanocomposites were obtained by non-covalent interaction. The positive gold nanoparticles prepared by phase inversion method exhibited good dimensional homogeneity and dispersibility, which could readily combine with single-stranded DNA modified reduced graphene oxide nanocomposites by electrostatic interactions. The modification of single-stranded DNA endowed the reduced graphene oxide with favorable biocompatibility and provided the preferable surface with negative charge for further assembling of gold nanoparticles to obtain gold nanoparticles/single-stranded DNA modified reduced graphene oxide nanocomposites with better conductivity, larger specific surface area, biocompatibility and electrocatalytic characteristics. The as-prepared nanocomposites were applied as substrates for the construction of cholesterol oxidase modified electrode and well realized the direct electron transfer between the enzyme and electrode. The modified gold nanoparticles could further catalyze the products of cholesterol oxidation catalyzed by cholesterol oxidase, which was beneficial to the enzyme-catalyzed reaction. The as-fabricated bioelectrode exhibited excellent electrocatalytic performance for the cholesterol with a linear range of 7.5−280.5 μmol·L⁻¹, a low detection limit of 2.1 μmol·L⁻¹, good stability and reproducibility. Moreover, the electrochemical biosensor showed good selectivity and acceptable accuracy for the detection of cholesterol in human serum samples.     

Tight binding of the antitumor drug ditercalinium to quadruplex DNA

The structural selectivity of the DNA-binding antitumor drug ditercalinium was investigated by competition dialysis with a series of nineteen different DNA substrates. The 7H-pyridocarbazole dimer was found to bind to double-stranded DNA with a preference for GC-rich species but can in addition form stable complexes with triplex and quadruplex structures. The preferential interaction of the drug with four-stranded DNA structures was independently confirmed by electrospray mass spectrometry and a detailed analysis of the binding reaction was performed by surface plasmon resonance (SPR) spectroscopy. The BIAcore SPR study showed that the kinetic parameters for the interaction of ditercalinium with the human telomeric quadruplex sequence are comparable to those measured with a duplex sequence. Slow association and dissociation were observed with both the quadruplex and duplex structures. The newly discovered preferential binding of ditercalinium to the antiparallel quadruplex sequence d(AG(3)[T(2)AG(3)](3)) provides new perspectives for the design of drugs that can bind to human telomeres.