A novel cell transfection platform based on laser optoporation mediated by Au nanostar layers

The recently developed laser‐induced cell transfection mediated by Au nanoparticles is a promising alternative to the well‐established lipid‐based transfection or to electroporation. Optoporation is based on the laser plasmonic heating of nanoparticles located near the cell membrane. However, the uncontrollable cell damage from intense laser pulses and from random attachment of nanoparticles may be crucial for transfection. We present a novel plasmonic optoporation technique that uses Au nanostar layers immobilized in culture microplate wells. HeLa cells were grown directly on Au nanostar layers, after which they were subjected to continuous‐wave 808 nm laser irradiation. An Au monolayer density ~15 μg/cm² and an absorbed energy of about 15 to 30 J were found to be optimal for optoporation. Propidium iodide molecules were used as model penetrating agent. The transfection efficiency evaluated using fluorescence microscopy for HeLa cells transfected with pGFP under optimized optoporation conditions (95% ± 5%) was similar to the efficiency of TurboFect. The technique's efficiency (295 ± 10 relative light units, RLU), demonstrated by transfecting HeLa cells with the pCMV‐GLuc 2 control plasmid, was greater than that obtained by transfection of HeLa cells with the TurboFect agent (220 ± 10 RLU). The cell viability in plasmonic optoporation (92% ± 7%), too, was greater than that in transfection with TurboFect (75% ± 7%).      

Sensitivity enhancement of DNA sensors by nanogold surface modification

A novel amplified microgravimetric gene sensing system was developed using quartz crystal microbalance modified by gold nanoparticles anchored on its 1,6-hexanedithiol modified gold electrode surface, and ultrasensitive detection of DNA hybridization was accomplished at the level of at least 2 x 10(-16) M.     

Au/TiO2–gC3N4 Nanocomposites for Enhanced Photocatalytic H2 Production from Water under Visible Light Irradiation with Very Low Quantities of Sacrificial Agents

Here for the first time the design and optimization are presented of a three‐component Au/TiO₂–gC₃N₄ nanocomposite photocatalyst able to efficiently produce H₂ from water using very low amounts of sacrificial agents and under visible light irradiation. This enhanced photocatalytic behavior compared to Au/TiO₂ and Au/gC₃N₄ materials is the result of synergetic effects due to high quality assembly and interface between the three components. This optimized nanoscale assembly characterized by simultaneous favorable nanoheterojunction formation between g‐C₃N₄ and TiO₂ semiconductors, as well as AuNPs/gC₃N₄ and AuNPs/TiO₂ junctions, leads to enhanced visible light harvesting, charge separation, and H₂ production. This composite photocatalyst yields a high H₂ production (350 µmol^?1 h^?1 g_catalyst^?1) under visible light irradiation with minimal amounts of sacrificial agent (≤1 vol%), corresponding to activities much higher than reported so far under comparable conditions.     

A new scheme of hybridization based on the Au(nano)-DNA modified glassy carbon electrode

DNA hybridization on the Au(nano)-DNA modified glassy carbon electrode (GCE) was investigated. The thiol modified probe oligonucleotides (SH-ssDNA) at the 5' phosphate end were assembled on the Au(nano)-DNA modified GCE surface. The electrochemical response of the probe immobilization and hybridization with target DNA was measured by differential pulse voltammetry (DPV) using methylene blue (MB) as the electroactive indicator. Gold nanoparticles can be dispersed effectively on the GCE surface in the presence of calf thymus DNA. Au(nano)-DNA modified GCE could greatly increase the active sites and enhance the response signal during immobilization and hybridization. The hybridization amount of target DNA could be greatly increased. The linear detection range of Au(nano)-DNA electrode for the complementary 21-mer oligonucleotide (cDNA) was achieved from 1.52 x 10(-10) to 4.05 x 10(-8) mol L(-1). The detection limit could reach the concentration of 10(-10) mol/L.     

A simple method for detecting steroid aggregation and estimating solubility in aqueous solutions

Steroids are generally sparingly soluble in water. Thus, for in vitro studies of steroid metabolism or enzymology it is common practice to solubilize steroids by the addition of a small amount (2–10%, v/v) of an organic cosolvent. Methanol, ethanol, and 1,2-propanediol, singly or in combination, have been widely used (1). Effects of organic solvents on the kinetic parameters, K_m and V_max, of steroid-metabolizing enzymes with various substrates have been demonstrated (2,3), and the results are consistent with the conclusion that organic solvent influences on catalytic activity reflect, in part, effects on the aggregation state and solubility of steroid substrates.Light-scattering measurements have been applied extensively in studies of macromolecular structure (4) and micelle formation by a large variety of amphiphilic substances [reviewed in Ref. (5)]. Jones and Gordon (6) used a commercial instrument, designed specifically for light-scattering measurements, to characterize micelle formation in aqueous solutions by Δ5-3-ketosteroids containing various substituents at the 17β position. They showed that turbidity versus concentration plots were of the form seen in studies of micelle formation (5) and that steroids can exist in solution in monomeric or micellar forms, their aggregation state being a function of the polarity of the steroid solute and the composition of the solvent.To estimate solubility quantitatively ³H- or ¹⁴C-labeled steroids have been used in conjunction with centrifugation (3), dialysis (7), or filtration (8). These techniques allow for accurate estimates of solubility, but one may encounter problems due to nonspecific absorption on membranes or the unavailability of the labeled steroid of interest.We have observed that steroid aggregation and solubility can be estimated easily and with high sensitivity with a commercially available fluorometer. In this report the method is described and examples demonstrating the reproducibility and sensitivity of the technique are presented.     

Near infrared sensing based on fluorescence resonance energy transfer between Mn:CdTe quantum dots and Au nanorods

A novel sensing system based on the near infrared (NIR) fluorescence resonance energy transfer (FRET) between Mn:CdTe quantum dots (Qdots) and Au nanorods (AuNRs) was established for the detection of human IgG. The NIR-emitting Qdots linked with goat anti-human IgG (Mn:CdTe-Ab1) and AuNRs linked with rabbit anti-human IgG (AuNRs-Ab2) acted as fluorescence donors and acceptors, respectively. FRET occurred by human IgG with the specific antigen–antibody interaction. And human IgG was detected based on the modulation in FRET efficiency. The calibration graph was linear over the range of 0.05–2.5 μM of human IgG under optimal conditions. The proposed sensing system can decrease the interference of biomolecules in NIR region and increase FRET efficiency in optimizing the spectral overlap of AuNRs with Mn:CdTe Qdots. This method has great potential for multiplex assay with different donor–acceptor pairs.     

Dynamic injection behaviour of carbon monoxide nano-jets: analysis based on molecular dynamics simulation

Molecular dynamics simulation was used to characterise the dynamical injection behaviour of CO through a gold nano-injector with a Gr coating. We also varied the nozzle outlet size, system temperature, and extrusion velocity to elucidate their influence on the flow patterns, injection pressure, and flow rate of the CO nano-jets. Simulation results revealed the following important findings. (1) At 100?K, the liquefaction of a CO jet led to a wider spray angle (ø_s?=?84～96°) and allowed molecules to attach to the Gr layer, resulting in agglomeration at the orifice. (2) At 500?K and 55.824?m/s, the nebulisation of the CO nano-jet was induced, which produced a narrower spray angle (ø_s?=?47°). (3) The flow rate of CO molecules was essentially linear under the following conditions: low extrusion velocity (≤13.956?m/s), large orifice (d?=?1.5?nm), and high system temperature (≥300?K). (4) Due to the compressibility of CO molecules, the pressure inside the chamber under a high extrusion speed (≥27.912?m/s) presented a sharp increase in the middle and final extrusion stages. A delay in the pressure increase enabled the liquefaction of the extruded CO molecules, resulting in an unstable flow rate.     

山东省台上金矿区赤松林叶绿素含量的季节动态

在1991年春、夏、秋三个季节对山东省招远市台上金矿区赤松林叶绿素含量的变化进行了测定,并与背景区作比较,对金矿区和背景区赤松针叶中的Au、Ag、Cu、Pb元素含量也进行了比较。金矿区和背景区Au、Ag、Cu、Pb元素含量有明显差异,金矿区高于背景区数倍,这对赤松的生长有一定影响,与叶绿素含量有一定的正相关;无论金矿区还是背景区,赤松一年生叶和二年生叶的叶绿素总量变化规律大体一致,都是春季较低,随气温上升而开始增加,至夏末达到最大值,然后从秋季开始下降,金矿区叶绿素总量低于背景区,一年生叶略高于二年生叶;当叶绿素总量变化时,叶绿素a/b的比率稍有波动,但几乎保持不变,金矿区和背景区也无差异。     

Amplification of blue emission of Tm3+ ions in Li2O-HfO2-SiO2 glass system by means of Au0 metallic particles

Li₂O-HfO₂-SiO₂-Tm₂O₃:Au₂O₃ glass samples (containing fixed content of Tm₂O₃ and different concentration of Au₂O₃) were prepared and characterized. Bearing of Au⁰ metallic particles (MPs) on improving blue emission of thulium ions (Tm³⁺) ions was explored. Optical absorption (OA) spectra exhibited multiple bands excited from ³H₆ of Tm³⁺. Additionally, a broad peak in the wavelength range 500–600 nm due to surface plasmon resonance (SPR) of Au⁰ MPs was noticed in the spectra. Photoluminescence (PL) spectra (of thulium free glasses) indicated a peak in the visible range due to sp → d electronic transition of Au⁰ MPs. Luminescence spectra of Tm³⁺ and Au₂O₃ co-doped glasses exhibited intense blue emission with substantial increase of intensity with increase of Au₂O₃ content. Bearing of Au⁰ MPs on the reinforcement of blue emission of Tm³⁺ was discussed in detail with kinetic rate equations.