基于PbS QDs/TiO2 NPs构建新型谷胱甘肽光电化学传感器

通过高温煅烧将二氧化钛纳米颗粒(TiO₂ NPs)修饰到ITO电极表面制成TiO₂ NPs/ITO电极, 再采用连续离子层吸附反应(SILAR)循环将硫化铅量子点(PbS QDs)修饰到TiO₂/ITO电极表面制得PbS QDs/TiO₂ NPs/ITO电极, 并将该电极应用于检测谷胱甘肽(GSH)的光电化学传感器. 在该传感器中, 当PbS QDs受470 nm可见光的激发时将产生电子(e)和光生空穴(h ⁺), 光生空穴可被溶液中的GSH捕获, 并将GSH氧化成GSSH, 有效避免电子和空穴的复合, 显著提高了光电效率. 该传感器对GSH的检测具有较高的灵敏度和选择性, 线性检测范围为0.06~1 mmol/L, 检出限(LOD)为4.6×10 ^-3 mmol/L(S/N=3).     

pH dependent interaction of biofunctionalized CdS nanoparticles with nucleobases and nucleotides: A fluorimetric study

The interaction of DNA bases and corresponding nucleotides with CdS nanoparticles (NPs), biofunctionalized by cysteine, has been investigated by absorption and fluorescence spectroscopy. Unique enhancement effect of adenine, in contrast to other nucleobases, on the luminescence of cysteine capped CdS (cys-CdS) NPs at both pH 7.5 and 10.5 was found, the extent of enhancement being much higher at pH 10.5. At the latter pH, the difference optical absorption spectra show development of new peak at 278 nm with corresponding decrease in the absorption of adenine at 260 nm, which is attributed to binding of adenine anion to the CdS surface through N7 of the purine ring. Appearance of a new band at 478 cm⁻¹ and concomitant shift in the C₈-N₇ vibrations to 1610 cm⁻¹ in the FTIR spectra of cys-CdS NPs with adenine also suggest Cd-N7 binding on the particle surface. Amongst various nucleotides, ATP exhibited maximum luminescence enhancement on CdS NPs for a given change in concentration in the micro-molar range at physiological pH. A quantitative correlation between ATP concentration and PL enhancement of CdS NPs has been established, a step which in future might assist in developing new protocols for fluorescence sensing of adenine nucleotides under certain pathological conditions.     

Preparation of polymer-dispersed liquid crystal doped with indium tin oxide nanoparticles

To study polymer-dispersed liquid crystal (PDLC) films doped with indium tin oxide (ITO) nanoparticles (NPs), samples were prepared by ultraviolet-initiated polymerisation based on the thiol–acrylate system. Owing to the interaction between PDLC system and ITO NPs, the content and the size of ITO NPs are the main determinants to the microstructure which plays an essential role on the electro-optical and anti-infrared properties of the PDLC films. In the polymer matrix, a novel microstructure consisting of a dense surface, micron-sized meshes and submicron meshes is found to benefit the better performances of the low driven voltage (20.7 V), the relatively high contrast ratio (8.3) and the lowest transmittance(500–2500 nm) on average at about 3.55% with maximum of merely 7.6%. Thus, it lays a solid foundation for the further investigations on the microstructure and the performance of the PDLC films. Meanwhile, it is proved that the PDLC film, improved performance through doping ITO NPs, is promising to be a superior choice in the field of energy-saving.     

Efficient chemiluminescence by aptamer – reactant platform combination with activated Ag–Au alloy nanoparticles for cobalt detection

This article deals with the detection of Co(II) in real water sample using aptamer – reactant platform combination with activated Ag–Au alloy nanoparticles (NPs) by chemiluminescence (CL) method. CL is attributed to a catalytically enhanced decomposition of H₂O₂ by aptamer conjugated Ag–Au alloy NPs to produce reactive oxygen species. The Ag–Au alloy NPs were prepared by chemical method using double reducing agent (i.e. trisodium citrate and polyethylenimine) and used for detection of Co(II) from water by CL method. CL experiments were carried out with the variation of different parameters such as pH, concentration of luminol, concentration of H₂O₂ and Ag–Au alloy NPs. We found that Ag–Au alloy NPs have very good efficiency towards Co(II) detection. Analytical parameters and kinetics were studied in detail to know the nature and mechanism of CL in presence of aptamer conjugated Ag–Au alloy NPs. The linear range of the CL sensor of Co(II) is covered concentration from 0.01 to 10 µg/L with detection limit of 0.001 µg/L. The relative standard deviation for determination of Co(II) was 6.65 in 10 replicated measurements. CL method is first time applied to detect the Co(II) in real water samples at very low level using aptamer conjugated Ag–Au NPs as a catalyst.     

Poly(butyl methacrylate)-grafted alginate/Fe3O4 nanocomposite: Synthesis and its application for removal of dyes

This study involved the utilization of a free radical-graft copolymerization reaction for the development of a novel adsorbent, namely, poly(butyl methacrylate)-grafted alginate/Fe₃O₄ nanocomposite (PBMA-gft-Alg/Fe₃O₄). Transmission electron microscopy, scanning electron microscopy, energy-dispersive X-ray analysis, X-ray diffraction patterns analysis, and Fourier transform infrared spectroscopy (FT-IR) were carried out for the characterization of Fe₃O₄ NPs and PBMA-gft-Alg/Fe₃O₄ nanocomposites. The capability of nanocomposites and nanoparticles to adsorb dyes such as MG and MB, resulting in their removal from aqueous media, was evaluated under different conditions such as pH, temperature, contact time, and dose of adsorbent. Optimum parameters for adsorption of dyes were found to be pH of 10, 50°C, contact time of 180 min, and 0.2 g of adsorbent. Efficiency of the PBMA-gft-Alg/Fe₃O₄ nanocomposite was found to be significantly greater than that of Fe₃O₄ NPs for eliminating the desired dye. Langmuir, Freundlich, Sips, and Temkin models were used for testing the experimental data. Freundlich model was the one that best described the adsorption.     

Biosynthesis of Nickel oxide Nanoparticles from Euphorbia heterophylla (L.) and their biological application

Nickel oxide Nanoparticles (NiO NPs) were synthesized from E. heterophylla (L.) leaves extract act as reducing/capping agent by biosynthesis process. Further the synthesized NiO NPs was subjected for structural, optical and biological properties. The XRD pattern of NiO NPS exhibit face centred cubic (FCC) crystalline structure. The UV-DR spectrum of biosynthesized NiO NPs exhibited optical properties with well-defined at 321 nm and its exhibits optical band gap is 3.24 eV. The FT-IR spectrum of NiO NPs shows stretching vibration of Ni-O at 452 cm⁻¹. The morphological features of NiO NPs are rhombohedra and slightly agglomerated and then size of the biosynthesized NiO NPs as found in the range of 12–15 nm. The NiO NPs shows vital non-toxic properties on human erythrocytes and its interference in activity coagulation cascade both on PRP and PPP on human blood. The Bactericidal activity of NiO NPs was shows significant inhibitory activity against pathogenic bacterial strains. Further, NiO NPs show significant cytotoxicity against human lung cancer cell line (A549) and human hepatocarcinoma (HepG2) cell lines. Therefore, the study reveals states that, the E. heterophylla (L.) leaves extract is an effective reducing/capping agent for the formation of NiO NPs and its exhibits biological properties.     

Bioinspired synthesis of multifunctional silver nanoparticles for enhanced antimicrobial and catalytic applications with tailored SPR properties

In the developing nanotechnology world, numerous attempts have been made to prepare the nobel metallic nanoparticles (NPs), which can improve their applicability in diverse fields. In the present work, the biosynthesis of silver (Ag) NPs has been successfully achieved through the medicinal plant extract (PE) of G. resinifera and effectively used for the catalytic and antibacterial applications. The size dependant tuneable surface plasmon resonance (SPR) properties attained through altering precursor concentrations. The X-ray and selected area diffraction pattern for Ag NPs revealed the high crystalline nature of pure Ag NPs with dominant (111) phase. The high-resolution TEM images show the non-spherical shape of NPs shifting from spherical, hexagonal to triangular, with wide particle size distribution ranging from 13 to 44 nm. Accordingly, the dual-band SPR spectrum is situated in the UV–Vis spectra validating the non-spherical shape of Ag NPs. The functional group present on the Ag NPs surface was analysed by FT-IR confirms the capping and reducing ability of methanolic PE G. resinifera. Further, the mechanism of antimicrobial activity studied using electron microscope showed the morphological changes with destructed cell walls of E. coli NCIM 2931 and S. aureus NCIM 5021 cells, when they treated with Ag NPs. The Ag NPs were more effective against S. aureus and E. coli with MIC 128 μg/ml as compared to P. aeruginosa NCIM 5029 with MIC 256 μg/ml. Apart from this, the reduction of toxic organic pollutant 4-NP to 4-AP within 20 min reveals the excellent catalytic activity of Ag NPs with rate constant k = 15.69 s^?1.     

PLGA/O-CMC载药纳米粒子的体外释药行为研究

本文以聚乳酸-乙醇酸共聚物(PLGA)和自行制备的O-羧甲基壳聚糖(O-CMC)为原料,以5-氟尿嘧啶(5-FU)为抗癌药物模型,采用自身设计的改良复乳法制备了载药纳米微粒。微粒平均粒径为98.5nm,粒径分布指数为0.192,粒子表面∈电位为61．48eV,载药率高达18．9％,包封率为86％。然后用SEM动态监测载药纳米粒子降解过程中表面形貌的变化,并连续追踪粒子降解过程中的质量损失和降解介质的pH变化。载药纳米粒子在PBS中的释药行为研究表明：(1)前12h的释药动力学符合Huguchi方程,具有一级释放特性;(2)在20天内的释药动力学符合零级释放特性。     

An ultrasensitive electrochemical immunosensor for CA72-4 based on a signal amplification strategy of MoS2 nanoflower-supported Au nanoparticles

Accurate detection of cancer antigen 72-4 (CA72-4), a tumor-associated glycoprotein, is of great significance for gastric cancer diagnosis and immunotherapy monitoring. Modification of noble metal nanoparticles on transition metal dichalcogenides can significantly enhance functions, such as electron transport. Molybdenum disulfide gold nanoparticles nanocomposites (MoS₂-Au NPs) were prepared in this study and a series of characterization studies were carried out. In addition, a label-free, highly sensitive electrochemical immunosensor molybdenum disulfide -Au nanoparticles/Glassy carbon electrode (MoS₂-Au NPs/GCE) was also prepared and used for the detection of CA72-4. The electrochemical performance of the immunosensor was characterized by electrochemical techniques, such as cyclic voltammetry (CV), differential pulse voltammetry (DPV), and electrochemical impedance spectroscopy (EIS). The results indicated that better MoS₂-Au NPs nanomaterials have been synthesized, and the prepared electrochemical immunosensor, MoS₂-Au NPs/GCE, showed excellent electrochemical performance. The sensor exhibited high detection sensitivity under optimal conditions, including an incubation time of 30 min, an incubation temperature of 25 °C, and a pH of 7.0. The electrochemical immunosensor also had a low detection limit of 2.0 × 10^?5 U/mL (S/N = 3) in a concentration range of 0.001–200 U/mL, with good selectivity, stability, and repeatability. In conclusion, this study provided a theoretical basis for the highly sensitive detection of tumor markers in clinical biological samples.     

Catalytic reduction of 4-nitrophenol using synthesized and characterized CoS@MorphcdtH/CoS@4-MPipzcdtH nanoparticles

CoS@MorphcdtH NPs and CoS@4-MPipzcdtH NPs were synthesized by precipitation method involving three mechanisms: inclusion, occlusion, and adsorption. The synthesized NPs were characterized with the help of UV-Vis spectroscopy, FESEM-EDAX, powder x-ray diffraction, TEM, ESIMS, TG/DSC analysis. The morphology of the CoS@MorphcdtH NPs and CoS@4-MPipzcdtH NPs were hexagonal and rectangular, and the particles were in the range 7–12 nm. UV–visible spectral measurements showed surface plasmon resonance at 320 nm–340 nm with band gap of 3.65 eV–3.86 eV. The catalytically active CoSNPs called were investigated for the reduction of 4-nitrophenol (4-NP) via hydrogenation using sodium borohydride (NaBH₄) as a reducing agent. Both the CoS NPs successfully reduced 4-NP to 4- aminophenol (4-AP) in a short time, catalytic performances are almost unchanged for the first five cycles. Herein, we report the preparation and characterizations of efficient active CoS NPs consisting carbodithioic acid framework as a support/capping material, along with catalytic property.