酶消解-单颗粒电感耦合等离子体质谱法测定农产品中纳米铂颗粒

铂纳米颗粒在汽车行业中被广泛用作汽车尾气催化剂.随着铂纳米颗粒在工业生产中的广泛应用,它在环境中广泛分布并可能从植物累积进入食物链中.因此,建立一种在农产品中的定量分析方法是至关重要的.以酶消解的前处理方法结合单颗粒-电感耦合等离子体质谱法(Single particle ICP-MS,SP-ICP-MS)测定农产品中...     

甲醛在铂纳米颗粒修饰电极上的电化学响应及其应用

用铂纳米颗粒直接修饰玻碳电极,制成了具有大表面积的纳米铂修饰电极.该电极对甲醛的电催化氧化明显优于铂盘电极,电化学响应显著.在碱性介质循环伏安分析中,氧化峰电流与甲醛浓度呈良好的线性关系,检出限为3.8×10(-5)mol/L(1.3μg/L),且多次测量中甲醛氧化峰电流相对标准偏差为1.9%.该修饰电极可用于腐竹提取...     

大麦醇溶蛋白负载白藜芦醇自组装纳米颗粒及其性质研究

采用液-液分散法自组装大麦醇溶蛋白纳米颗粒,重点考察了溶剂(异丙醇)浓度、大麦醇溶蛋白浓度、溶液p H值及离子强度等因素对自组装纳米颗粒粒径和Zeta电位的影响。结果表明:在选择溶剂(异丙醇)浓度为55%,蛋白质浓度为66 mg/m L,分散液p H值为7.0,离子强度为0时,自组装出粒径为(70.0±1.8)nm,Zeta电位9 m V的大麦醇溶蛋白纳米颗粒。在此基础上,进一步制备了白藜芦醇-大麦醇溶蛋白复合纳米颗粒,考察了芯材比对复合纳米颗粒粒径、包封率及载药率的影响,结果表明,当芯材比为1∶5时,自组装复合纳米颗粒的粒径为(135.3±2.5)nm,Zeta电位为(18.91±0.02)m V,包封率为90.4%,载药率为18.8%。扫描电子显微镜结果表明,大麦醇溶蛋白纳米颗粒以及白藜芦醇-大麦醇溶蛋白复合纳米颗粒均为表面光滑的球形颗粒;傅立叶变换红外光谱结果表明,复合纳米颗粒中白藜芦醇与大麦醇溶蛋白之间还存在较强的氢键与静电相互作用。     

纳米铂修饰玻碳电极对邻苯二酚的电化学氧化及测定

应用循环伏安法研究了邻苯二酚在纳米铂修饰玻碳(PtNPs/GC)电极上的电化学氧化行为。实验表明,PtNPs/GC电极对邻苯二酚有很强的电催化作用,其伏安扫描氧化峰电流随着温度的升高而增大,但氧化峰电位略有负移。常温下,邻苯二酚能自发在电极表面发生聚合反应,生成具有导电性的聚合膜,其催化氧化电流与邻苯二酚浓度在1.0×10-6mol/L~5.0×10-5mol/L范围内呈良好的线性关系,检出限为2.9×10-7mol/L。     

超声辅助提取/单颗粒电感耦合等离子体质谱法测定防晒化妆品中的纳米二氧化钛

建立了超声辅助提取/单颗粒电感耦合等离子体质谱(SP-ICP-MS)测定防晒化妆品中纳米TiO_2的方法。考察了停留时间、纳米粒子数量及浓度等分析条件,确定了防晒化妆品中纳米TiO_2的最佳萃取条件以及测定方法,对比了不同萃取溶剂对防晒霜中纳米TiO_2的提取效果。结果表明,在采用0. 1%Tritonx-100(Tx-100)以及5%乙醇作为萃取剂超声辅助提取,测定停留时间为3 ms,待测样品中纳米颗粒的数量浓度低于4×10~7个/mL条件下,该法可准确测定防晒化妆品中的纳米TiO_2,对防晒化妆品中纳米TiO_2的数量浓度检出限(LOD_(conc))为1×10~4个/mL,纳米颗粒粒度检出限(LOD_(size))为35 nm。方法简单快捷、灵敏度高、准确性良好,可同时对防晒化妆品中TiO_2进行浓度测定及粒度分布表征。     

纳米银的单颗粒-电感耦合等离子质谱法表征及其测定

建立单颗粒-电感耦合等离子体质谱法( SP-ICP-MS)测定稀溶液中纳米银颗粒粒度分布及纳米银颗粒数量浓度的方法。当停留时间为3 ms时,两个或多个纳米银颗粒同时进入检测器的可能性降至最低。采用5倍标准偏差迭代算法(5σ)区分纳米银颗粒信号和背景信号。采用SP-ICP-MS法测定3种商品级纳米银颗粒(30,50和100 nm)粒度分布和纳米颗粒浓度。结果表明：SP-ICP-MS法测定纳米银颗粒结果与纳米银的TEM值相近,可采用SP-ICP-MS法表征纳米银颗粒。本方法测定稀溶液中纳米银颗粒粒度检出限为25 nm,纳米银颗粒浓度检出限约为8×104个/L。将纳米银颗粒加入到自来水样品中并进行测定,获得相近的纳米银粒度分布及纳米颗粒浓度。本方法简单、快捷、灵敏度高,可为研究水环境中纳米银的风险评估提供可靠分析方法,并为饮用水中纳米银的监测提供分析技术。     

单颗粒-电感耦合等离子体质谱测定金纳米颗粒

单颗粒-电感耦合等离子体质谱法(Single particle-inductively coupled plasma-mass spectrometry,SPICP-MS)是近年出现的一种纳米材料分析方法,可用于表征纳米材料的元素组成、粒径分布以及颗粒物浓度。本研究对比了驻留时间(Dwell time,t_d)和稳定时间(Settling time,t_s)等质谱参数对单颗粒分析结果的影响,分析了金纳米颗粒标准物质(NIST 8012,NIST 8013,GBWE 120127)。结果表明,使用短的驻留时间(0.05 ms)和稳定时间(0 ms),可以获得更高的信噪比,检测到更多的纳米颗粒。利用本方法分析了AuNP标准物质,得到的粒径结果与标准值相符。本方法对金纳米颗粒的数量检出限为1.1×10~5L~(-1),粒径检出限为8 nm。     

碳纳米管负载铂颗粒酶电极葡萄糖传感器

以碳纳米管负载纳米铂颗粒修饰玻碳电极 (CNT Pt/GCE)为基底 ,用明胶固定葡萄糖氧化酶(GOD) ,构建了电流型葡萄糖生物传感器 (GOD/CNT Pt/GCE)。在实验中 ,GOD/CNT Pt/GCE显示了良好的分析性能 ,与常规铂电极葡萄糖传感器 (GOD/Pt)相比较 ,测定葡萄糖的检出限从 6 .7× 10 -3 mol/L下降到8.3× 10 -4mol/L ;工作电位从 0 .6 5V下降至 0 .4 5V ;响应时间从 30s下降至 5s左右。实验结果表明 ,具有高度电催化活性的CNT Pt/GCE可作为酶传感器的一种新型基体电极。     

酶提取-单颗粒电感耦合等离子质谱法分析樱桃番茄纳米银颗粒及其吸收规律研究

为探究复合保鲜涂膜中AgNPs的迁移情况，采用酶提取的前处理方式，结合单颗粒电感耦合等离子体质谱（SP-ICP-MS），考察了前处理方式、驻留时间、校准方式以及Ag+浓度等条件对AgNPs准确测定的影响。结果表明：0.1 g樱桃番茄样品在柠檬酸盐体系下使用0.2 g的R-10离析酶可达到消解最适酶剂量；当驻留时间小于100 μs时，测定结果有较好的积分条件以及较高的信背比；采用AgNP尺寸方式进行校准比单独用Ag+标准溶液校准方式的颗粒尺寸测定结果更加准确。采用该方法测定樱桃番茄中加标AgNPs颗粒回收率达到88.9%，粒径实测值为47.8±0.3 nm，粒径检出限为13 nm，颗粒浓度检出限为 7.5×104 particles/L。通过将樱桃番茄暴露于AgNPs涂膜中来探究AgNPs迁移行为，复合保鲜涂膜后的樱桃番茄通过三次洗涤后能够在表面去除大部分AgNPs，但仍有少量AgNPs穿过果表皮浸入果肉组织。该方法灵敏度高，操作简单，能够为揭示AgNPs在农产品及农业生产中的风险提供可靠、准确的表征方法。     

纳米铂颗粒修饰薄膜金电极的新型葡萄糖传感器研究

在没有引入电子媒介体条件下,为了提高传感器的响应灵敏度,降低工作电位,利用电化学沉积法在薄膜金电极表面修饰纳米铂颗粒,并通过戊二醛固定酶的方法制备了一种新型生物传感器。研究了在薄膜金电极上修饰纳米铂颗粒前后传感器对低浓度葡萄糖的响应影响。结果表明,纳米铂颗粒修饰后所制备的葡萄糖传感器工作电位下降为0.4 V,测定葡萄糖的检出限从100μmol/L下降到10μmol/L。传感器对10~1300μmol/L低浓度葡萄糖的响应灵敏度为50.8 nA/(cm2μmol/L);响应时间30 s;r为0.9974;传感器精密度为2.1%,并具有较好的稳定性。     

基于单颗粒电感耦合等离子体质谱法测定环境基质水样中纳米银颗粒

采用单颗粒电感耦合等离子体质谱法(SP-ICP-MS)同时测定环境水样中纳米银颗粒(AgNPs)的颗粒浓度、质量浓度和粒径分布,并考察了溶液的pH值、溶解性有机质(DOM)浓度以及离子强度等对AgNPs测定的影响。结果表明:SP-ICP-MS方法对60 nm AgNPs标准溶液的测定结果与标准值一致,准确性较好;pH值(5.0～7.0)、离子强度(≤1 mmol/L)和DOM浓度(≤30 mg/L)对测定结果影响较小;当溶液的pH值≤5.0或离子强度1 mmol/L时,AgNPs的颗粒浓度和粒径随pH值的下降或离子强度的增强而减小。采用SP-ICP-MS方法测定河水、染料废水、养殖废水3种水样中AgNPs的加标回收率分别为98.1%、83.3%和93.3%,表明该方法在合适的基质条件下可用于快速准确测定环境水样中AgNPs的颗粒浓度、质量浓度和粒径分布。     

基于表面重建螺旋型铂铱电极的葡萄糖生物传感器

通过对螺旋型铂铱电极表面进行化学腐蚀和电化学沉积铂纳米粒子实现电极表面的重建和优化,研究了螺旋型铂铱电极在不同腐蚀时间和电沉积时间下的形貌及对过氧化氢(H2O2)的催化活性.对表面重建的工作电极涂覆氧化酶和半透膜,制备出了铂纳米粒子/葡萄糖氧化酶/环氧聚氨酯酶电极,并将其用作葡萄糖传感器的工作电极.传感器计时电流检测结果表明,表面重建后的酶电极传感器对葡萄糖的检测范围扩大为2~45 mmol/L,优于裸铂铱酶电极传感器,电流响应值和灵敏度得到明显提升,同时传感器还具有良好的稳定性和选择性.     

Amperometric Glucose Biosensor Based on Platinum Nanoparticles Combined Aligned Carbon Nanotubes Electrode

A sensitive amperometric glucose biosensor based on platinum nanoparticles (PtNPs) combined aligned carbon nanotubes (ACNTs) electrode was investigated. PtNPs which can enhance the electrocatalytic activity of the electrode for electrooxidating hydrogen peroxide by enzymatic reaction were electrocrystallized on 4‐aminobenzene monolayer‐grafted ACNTs electrode by potential‐step method. These PtNPs combined ACNTs' (PtNPs/ACNTs) surfaces were characterized by scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The highly dispersed PtNPs on ACNTs can be obtained. The enzyme electrode exhibits excellent response performance to glucose with linear range from 1×10^?5–7×10^?3 mol L^?1 and fast response time within 5 s. Furthermore, this glucose biosensor also has good reproducibility. It is demonstrated that the PtNPs/ACNTs electrode with high electrocatalytic activity is a suitable basic electrode for preparing enzyme electrodes.     

Green synthesis of platinum nanoparticles using Atriplex halimus leaves for potential antimicrobial,antioxidant, and catalytic applications

Herein, green platinum nanoparticles (PtNPs) were synthesized using an aqueous extract of Atriplex halimus leaves as a reductant. Atriplex platinum nanoparticles (At-PtNPs) were stable for up to three months. At-PtNPs were characterized by several techniques including UV–Visible spectroscopy, Fourier Transform Infrared (FT-IR) spectroscopy, X-ray diffraction (XRD), Energy Dispersive X-ray spectroscopy (EDX), EDX elemental mapping, High-resolution Transmission electron microscope (HRTEM), Selected Area Electron Diffraction (SAED), and X-ray Photoelectron Spectroscopy (XPS) and Zeta measurements. At-PtNPs were black-colored and mainly spherical with a plasmon peak at 295 nm with ultra-small particle size (1–3 nm) and high surface charge (?25.4 mV). At-PtNPs were verified as a superb catalyst as they were able to catalytically degrade MB dye. At-PtNPs exhibited a high antibacterial efficiency against gram-negative bacteria. At-PtNPs were proved as a highly efficient antioxidant agent. Thus, the attained results offer a promising route of the green synthesis of PtNPs using the aqueous extract of Atriplex halimus.     

All-electrochemical approach for the assembly of platinum nanoparticles/polypyrrole nanowire composite with electrocatalytic effect on dopamine oxidation

In the present study, a composite material consisting of polypyrrole nanowires (PPyNWs) and platinum nanoparticles (PtNPs) has been developed by an all-electrochemical approach and proved to be highly effective for electrochemical determination of dopamine (DA). PPyNWs are electropolymerized by a template-free method, and PtNPs are subsequently electrodeposited by cyclic voltammetry. Chemical characterization by X-ray photoelectron spectroscopy showed the effective PtNP immobilization on polymer nanowires discriminating at the same time Pt species deposited and revealing the occurrence of polypyrrole-PtNP interaction. The morphology of the composite material was characterized using scanning electron microscopy that showed spherical Pt nanoparticles well distributed within PPy-NW network. DA detection was performed by differential pulse voltammetry technique obtaining satisfactory performances in terms of linear range (1–77 μM), sensitivity, reproducibility (RSD 2.7%), and detection limit (0.6 μM). The electrocatalytic role of PtNPs in DA electroxidation process is clearly demonstrated by the comparison with PPyNWs only. Moreover, no significant response is observed in the presence of common interference as ascorbic acid and uric acid, which may coexist with DA in biological fluids, demonstrating a good selectivity toward DA. Moreover, DA was detected in human serum samples spiked obtaining a satisfactory recovery of 94%. A synergistic effect involving both PtNPs and PPyNWs is invoked for explaining the observed electrocatalytic activity.     

In situ chemical reductive growth of platinum nanoparticles on glass slide for the mass fabrication of biosensors

Platinum nanoparticles (PtNPs) attached to glass slide surface was successfully prepared by using a simple in situ chemical reduction method. In this method, a approximately 10nm gold layer was first sputtered uniformly onto the glass slide surface, PtNPs could be grown directly on the gold layer by immersing the glass slide into the grown solution containing H(2)PtCl(4) and ascorbic acid. The gold layer sputtered uniformly serves as "seed" for the following growth of PtNPs and high dense of PtNP modified film can be prepared. Control experiment without the gold layer found no obvious formation of PtNPs indicating the importance of the "seed". The electrocatalytic effect of the PtNP film was investigated with the detection of hydrogen peroxide and for the fabrication of biosensors. Glucose oxidase was selected and directly electrodeposited onto the PtNPs modified surface. The resulting biosensor has a fast response time (<10s) with wide linear range (5x10(-6) to 2x10(-2)). The fabrication method is simple, convenient and can be used for the mass fabrication of biosensors. The present preparation method of PtNPs modified film could be used for the preparation of other metal nanoparticle and find electrochemical applications as well as for optical uses.     

Functionalization of platinum nanoparticles for electrochemical detection of nitrite

In this work, a novel electrochemical method for nitrite detection by using functionalized platinum nanoparticles (PtNPs) is proposed. Firstly, a gold electrode is immobilized with 4-(2-aminoethyl)benzenamine. Then, PtNPs are modified with 5-[1, 2]dithiolan-3-yl-pentanoic acid [2-(naphthalene-1-ylamino)-ethyl]amide (DPAN). Consequently, in the presence of nitrite ions, Griess reaction occurs between 4-(2-aminoethyl)benzenamine on the electrode and DPAN on PtNPs, thus PtNPs are localized onto the electrode surface. So, PtNPs-electrocatalyzed reduction of H₂O₂ can be achieved to correlate the electrochemical signal with the concentration of nitrite ions. The linear concentration range can be as wide as 10–1,000 μM, while the detection limit is as low as 5 μM. The proposed method has been also successfully applied to the detection of nitrite with the local lake water, and the result is well consistent with that obtained by UV-visible spectrophotometric method. So, this method has potential use for monitoring nitrite in drinking water supplies in the future.     

Cisplatin-tethered gold nanoparticles that exhibit enhanced reproducibility, drug loading, and stability: a step closer to pharmaceutical approval?

Gold nanoparticles (AuNPs) can be used as delivery vehicles for platinum anticancer drugs, improving their targeting and uptake into cells. Here, we examine the appropriateness of different-sized AuNPs as components of platinum-based drug-delivery systems, investigating their controlled synthesis, reproducibility, consistency of drug loading, and stability. The active component of cisplatin was tethered to 25, 55, and 90 nm AuNPs, with the nanoparticles being almost spherical in nature and demonstrating good batch-to-batch reproducibility (24.37 ± 0.62, 55.2 ± 1.75, and 89.1 ± 2.32 nm). The size distribution of 25 nm AuNPs has been significantly improved, compared with a previous method that produces polydispersed nanoparticles. Attachment of platinum to the AuNP surface through a poly(ethylene glycol) (PEG) linker exhibits an increase in the drug loading with increasing particle size: 25 nm (815 ± 106 drug molecules per AuNP), 55 nm (14216 ± 880), and 90 nm (54487 ± 15996). The stability of the naked, PEGylated, and platinum-conjugated nanoparticles has been examined over time under various conditions. When stored at 4 °C, there is minimal variation in the diameter for all three AuNP sizes; variation after 28 days for the 25 nm AuNPs was 2.4%; 55 nm, 3.3%; and 90 nm, 3.6%. The 25 nm AuNPs also demonstrate minimal changes in UV-visible absorbance over the same time period.     

Application of platinum nanoparticles as affinity probe and matrix for direct analysis of small biomolecules and microwave digested proteins using matrix-assisted laser desorption/ionization mass spectrometry

We report the use of platinum nanoparticles (PtNPs) for analysis of amino acids, peptides, proteins and microwave digested proteins (lysozyme and bovine serum albumin) without any tedious washing and separation procedures prior to matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF-MS). In the present study, PtNPs play three functions, such as matrix, affinity probe and acceleration of protein digestion by absorbing the microwave irradiation. Good signal intensity of the target molecules from the sample was obtained when laser energy, NPs concentration and incubation time were set to 35 μJ, 25 nM and 30 min, respectively. In addition, higher numbers of peptide sequence were obtained for microwave digested lysozyme protein using PtNPs as compared to previously reported methods for analysis of digested protein in MALDI-MS. Thus, the present method is a simple, rapid and one step preparation method for the analysis of amino acids, peptides, proteins and digested proteins in MALDI-TOF-MS without the need for any tedious purifications and washing procedures.     

Dual detection strategy for electrochemical analysis of glucose and nitrite using a partitionally modified electrode

A dual-region modified electrode was designed and fabricated by means of partitioned electrodeposition of gold and platinum nanoparticles on an indium tin oxide (ITO) conductive glass for dual-component electrochemical detection. The two differently modified regions were assigned to detect two analytes, separately and simultaneously. The gold nanoparticle modified ITO region (AuNPs/ITO) was used for glucose detection while the platinum nanoparticle modified ITO region (PtNPs/ITO) for nitrite detection. The glucose oxidation peak current at 0.10 V on AuNPs/ITO exhibited a linear dependence on the concentration of glucose and was used to determine the concentration of glucose in dual-detection. The nitrite reduction peak current at PtNPs/ITO showed a nonlinear dependence on the concentration of nitrite. A theoretical model combining the adsorption-controlled and the mass-transfer-controlled kinetics was proposed to quantitatively describe the nonlinear behavior. Though the presence of glucose interfered with the electrochemical detection of nitrite, it was demonstrated that the influence of glucose on nitrite detection can be corrected. On the basis of the proposed theoretical model, the simultaneous dual-detection of glucose and nitrite was accomplished at ITO electrodes partitionally modified with AuNPs and PtNPs.