Fluorogenic Probes Applied to the Study of Induced Oxidative Stress in the Human Leukemic HL60 Cell Line

Development of microspectrofluorometric methods using specific fluorogenic probes has provided precious help in studying in situ oxidative stress and cellular protective systems. The aim of this study was to determine ROS production concomitantly with a modification of the intracellular thiol pool after applying an oxidative stress to a nonadherent cell model represented by the HL60 cell line. The dichlorodihydrofluorescein diacetate (H₂DCFDA) probe assessed the kinetic production of ROS by cells submitted to the chemical oxidant t-butylhydroperoxide with a high signal/noise ratio. The probe sensitivity permitted us to detect endogenous ROS production in HL60 cells and the protective effect of N-acetyl cysteine against ROS. The chloromethylfluorescein diacetate probe (CMFDA) permitted us to evaluate the thiol depleting effect of N-ethyl maleimide. Complete thiol depletion was associated with a moderate increase in ROS production. The cell viability was determined with calcein-AM, which gave results similar to those with the tetrazolium dye. This probe was not affected by intracellular pH and did not required an extraction step, unlike tetrazolium dye. In conclusion, cell-permeant fluorogenic probes are useful and sensitive tools to determine in situ ROS production concomitantly with consecutive change in the thiol system in a living and non-adherent cell model.     

基于气相沉积等离激元纳米粒子/三维石墨烯-镍泡沫复合结构的高灵敏度表面增强拉曼检测

本文提出一种基于气相沉积银纳米粒子和三维石墨烯-镍泡沫的复合等离激元结构.该结构是利用气相纳米团簇束流技术将高密度的银纳米粒子直接沉积于三维石墨烯-镍泡沫的表面制备而成.与传统银纳米结构相比,复合三维等离激元纳米结构具有"热点"数量多,局域场更强的特点,可作为基于表面增强拉曼技术的高灵敏度化学传感器.拉曼测试实验结果表明,该三维纳米结构在表面增强拉曼检测中可获得灵敏度高,重复性好的探针拉曼信号.通过进一步的理论模拟,发现该三维等离激元结构中增强的拉曼信号主要归因于纳米粒子与纳米粒子之间以及纳米粒子与石墨烯-镍泡沫衬底之间的多重近场耦合效应.     

Multienzyme-Mimetic Activity of Gold/Cerium Oxide Nanozyme

Redox-active nanozymes offer low-cost controlled synthesis, high stability, and tunable catalytic properties over natural enzymes, which have attracted wide attention in the field of disease diagnosis and treatment. However, the improvement of catalytic activity remains an important challenge for nanozymes. Herein, the Au/CeO₂ nanozymes is developed to achieve enhanced multiple enzyme-mimetic activity. The Au/CeO₂ nanozymes at 5% doping possess best peroxidase-like activity with threefold higher catalytic rate than CeO₂. For catalase-mimic catalysis, the Au/CeO₂ nanozymes at 5% doping also exhibited a 1.5-fold enhanced reaction rate higher than pure CeO₂. The superoxide dismutase (SOD)-like capacity of Au/CeO₂ nanozymes is proportional to Au content. The Au/CeO₂ nanozymes at 10% doping show optimal SOD-like capacity of 60.2 U mg⁻¹. In vitro experiments validate the regulation ability of intracellular oxidative stress and inflammation. Au/CeO₂ nanozymes can reduce lipopolysaccharide- or H₂O₂-induced oxidative damage by scavenging excess ROS in nerve cell. Therefore, Au/CeO₂ can be used as a promising antioxidant in disease treatment, and the study offers general guidelines for achieving enhanced biocatalytic property through atomic doping.     

Glutathione‐Mediated Degradation of Surface‐Capped MnO2 for Drug Release from Mesoporous Silica Nanoparticles to Cancer Cells

Owing to its higher concentration in cancer cells than that in the corresponding normal cells, glutathione (GSH) provides an effective and flexible mechanism to design drug delivery systems. Here a novel GSH‐responsive mesoporous silica nanoparticle (MSN) is reported for controlled drug release. In this system, manganese dioxide (MnO₂) nanostructure, formed by the reduction of KMnO₄ on the surface of carboxyl‐functionalized MSN can block the pores (MSN@MnO₂). By a redox reaction, the capped MnO₂ nanostructure can dissociate into Mn²⁺ in the presence of GSH molecules. The blocked pores are then uncapped, which result in the release of the entrapped drugs. As a proof‐of‐concept, doxorubicin (DOX) as model drug is loaded into MSN@MnO₂. DOX‐loaded MSN@MnO₂ shows an obvious drug release in 10 × 10^?3 m GSH, while no release is observed in the absence of GSH. In vitro studies using human hepatocellular liver carcinoma cell line (HepG2) prove that the DOX‐loaded MSN@MnO₂ can entry into HepG2 cells and efficiently release the loaded DOX, leading to higher cytotoxicity than to that of human normal liver cells (L02). It is believed that further developments of this GSH‐responsive drug delivery system will lead to a new generation of nanodevices for intracellular controlled delivery.     

The effect of pre-pattern on the morphology and growth speed of TiO2 nanotube

In this work, we presented a new method which directly acts on the surface of the Ti sheet by mechanical micro-etching using a grating ruling engine. The effect of the pre-pattern on the morphology and growth speed of TiO₂ nanostructure formed on the Ti sheet with the traditional anodization method was investigated. A novel wall structure was observed and the growth speed of TiO₂ nanotube (NT) was greatly affected by the pre-pattern. The wall structure increases the surface-to-volume ratio of the nanotube arrays. The new method provided the possibility of further optimization of fast growth of TiO₂ nanostructure and improving the efficiency of dye-sensitized solar cell (DSSC) and photocatalysis.     

Colloidal,Functional, Piezoelectric BaTiO3-Au Nanohybrid for Wireless Cell Therapy

Ultrasound-assisted reactive oxygen species (ROS) generation from piezoelectric nanomaterial offers unique wireless therapeutic approach in remote places. In the previous work, piezoelectric barium titanate (BaTiO₃) nanorod have been synthesized and used for wireless cell therapy. However, the piezoelectric property of BaTiO₃ nanorod needs further improvement for diverse applications. In this work, it is shown that gold nanoparticle conjugation with BaTiO₃ nanorod (BaTiO₃-Au) can significantly enhance the piezoelectric performance with the piezoelectric constant value of 110 pm V⁻¹. The colloidal BaTiO₃-Au is further functionalized with folate for selective targeting of folate-overexpressed cancer cells and used for wireless cell therapy via intracellular ROS generation under ultrasound exposure. The synthesized colloidal nanohybrid can be used for various therapeutic applications.     

Effect of nano-titanium hydride on formation of multi-nanoporous TiO2 film on Ti

The effect of titanium hydride on the formation of nanoporous TiO₂ on Ti during anodization has been investigated by X-ray photoelectron spectroscopy, grazing incident X-ray diffraction, transmission electron microscopy and scanning electron microscopy. Titanium hydride (TiH₂) was formed after cathodization, profoundly impacting the formation of nanoporous TiO₂ on Ti by anodization. Oxide layer and nanocrystal structure were observed after anodization with cathodic pretreatments. A multi-nanoporous TiO₂ layer was formed on the titanium. The titanium hydride is a nanostructure. The nanostructure is directly changed to nanoporous TiO₂ by a dissolution reaction during anodization. The nanoporous layer is difficult to form without cathodization. The nanostructural TiH₂ is important in forming a nanoporous TiO₂ layer. Anodization treatment with cathodic pretreatment not only yields a titanium surface with a multi-nanostructure, but also transforms the titanium surface into a nanostructured titanium oxide surface.     

Oxidation fracturing of the graphitic BN sheet

Graphitic BN sheets with well-defined structure are promising candidate materials for future applications in nanoelectronics and molecular devices. The local oxidation is regarded as an effective means to produce a regular nanostructure. However, the underlying fracturing mechanism of such system is unclear. Here we aim to resolve this issue by the ab initio method. we predict the equilibrium configuration and the oxidative cutting process by introducing an epoxy-like chain and an added oxygen atom placed nearby, respectively. The results show that the intermediate epoxy-like pair can be eventually broken up after a key structure formation of B₃O during the oxidative processes.     

A tunable spatial spin splitter based on a spin–orbit-coupling modulated magnetic nanostructure

We investigate theoretically the spin-dependent Goos–Hänchen (GH) effect in a magnetic nanostructure modulated by spin–orbit coupling (SOC), which can be experimentally realized by depositing a ferromagnetic (FM) stripe and a Schottky-metal (SM) stripe on the top and bottom of an InAs/Al_xIn_1?xAs heterostructure, respectively. We consider two kinds of different SOCs (Rashba and Dresselhaus types), and calculate the GH shift and its spin polarization for the electrons across the device. Results show that the GH shift still is spin-polarized after including the SOC, and the behavior of the spin-polarized electrons can be manipulated by the Rashba and/or Dresselhaus SOC. These interesting properties provide an alternative scheme for spatially realizing spin injection into a semiconductor, and the magnetic nanostructure can be employed as a controllable spatial spin splitter for a spin-polarized source in spintronics.     

Gallium-doped indium oxide nanoleaves: Structural characterization,growth mechanism and optical properties

The novel two-dimensional (2-D) Ga-doped In₂O₃ nanoleaves are synthesized by a simple one-step carbonthermal evaporation method using Cu–Sn alloy as the substrates. Two basic parts construct this leaf-like nanostructure: a long central trunk and two tapered nanoribbons in symmetric distribution in relation to the trunk. The Ga–In–O alloy particles are located at or close to the tips of the central trunks and serve as catalysts for the central trunk growth by the self-catalytic vapor–liquid–solid (VLS) mechanism. And the homoepitaxial growth of tapered nanoribbon on the surface of the central trunk can be explained by vapor–solid (VS) mechanism. The room-temperature photoluminescence (PL) measurement of this nanoscaled Ga-doped In₂O₃ transparent conducting oxide (TCO) detected two blue peaks located at 432 nm and 481 nm, respectively, which can be used by Ru-based dye and indicates potential application in dye-sensitized solar cells (DSSCs). The successful preparation of this novel 2-D Ga-doped In₂O₃ nanoleaves not only enriches the synthesis of TCO materials, but also provides new blocks in future architecture of functional nano-devices.     

Reciprocal Response of Human Oral Epithelial Cells to Internalized Silica Nanoparticles

Silica nanoparticles (SiO₂ NPs) are one of the most widely used engineered nanoparticles and can been found in a wide range of consumer products. Despite their massive global production scale, little is known about their potential effects in the context of unintended exposure or ingestion. Using TR146 cells as an in vitro model of the human oral buccal mucosa, the uptake, spatial intracellular distribution, reactive oxygen species (ROS) production, inflammatory response, and cytotoxic effects of commercial SiO₂ NPs are examined. SiO₂ NPs are shown to dock and cross the cellular membrane barrier in a dose–time‐dependent manner. Confocal sectioning reveals translocation of SiO₂ NPs into the cell nucleus after 12 h of exposure. A concentration threshold of more than 500 × 10^?6 m is observed, above which SiO₂ NPs are shown to exert significant oxidative stress with concomitant upregulation of inflammatory genes IL6 and TNFA. Further analysis of the p53 pathway and a series of apoptotic and cell cycle biomarkers reveals intracellular accumulation of SiO₂ NPs exert marginal nanotoxicity. Collectively, this study provides important information regarding the uptake, intracellular distribution, and potential adverse cellular effects of SiO₂ NPs commonly found in consumer products in the human oral epithelium.     

Cytotoxicity and drug release behavior of PNIPAM grafted on silica-coated iron oxide nanoparticles

The nanoparticles containing thermosensitive and magnetic properties were investigated for their potential use as a novel drug carrier for targeted and controlled release drug delivery system. These thermosensitive and magnetic nanoparticles were prepared by grafting thermosensitive poly (N-isopropylacrylamide) (PNIPAM) on the surface of silica (SiO₂)-coated Fe₃O₄ nanoparticles with the particle size of 18.8 ± 1.6 nm. Adsorption and desorption behavior of bovine serum albumin (BSA) on the surface of PNIPAM-grafted SiO₂/Fe₃O₄ nanoparticles was studied, and the results indicated that these nanoparticles were able to absorb protein at temperature above the lower critical solution temperature (LCST) and to be desorbed below the LCST. Cytotoxicity studies conducted on Chinese hamster ovary (CHO-K1) cells using methyl tetrazolium (MTT) assays revealed that cell viability of 1 mg/mL PNIPAM-grafted nanoparticles was slightly decreased after 24 h of incubation as compared to the lower concentration of nanoparticles. Furthermore, the concentration of 0.5 mg/mL PNIPAM-grafted nanoparticles was totally biocompatible for 48 h, but had low cytotoxicity after 72 h of incubation. These PNIPAM-grafted nanoparticles did not induce morphological change in their cellularity after exposure for 24 and 108 h. These results demonstrate that PNIPAM-grafted nanoparticles are biocompatible and have potential use as drug carriers.     

Renal Clearable Luminescent WSe2 for Radioprotection of Nontargeted Tissues during Radiotherapy

High‐energy ionizing radiation is widely used in medical diagnosis and cancer radiation therapy. However, high‐energy radiation can also impose significant damages in healthy tissues during medical treatments via direct DNA damages and indirect damages from production of reactive oxygen species (ROS). Therefore, it is urgent to develop highly effective radioprotectants with low toxicities that can meet the increasing needs for alleviating the adverse effects from cancer radiation therapy and nuclear emergency. In this work, strongly catalytic ultrasmall (sub‐5 nm) cysteine‐protected WSe₂ dots are employed to protect healthy tissues against radiation via diminishing radiation‐induced free radicals. The WSe₂ dots with high surface activities can recover radiation‐induced DNA damages and eliminate the excessive ROS generated from radiation. In vivo experiments confirm that the survival rate of mice treated with WSe₂ dots is significantly elevated with radiation damages postponed under exposure to high‐dose ionizing radiation. Furthermore, the free radicals in major organs and hematological system can be appreciably omitted, suggesting their unique role as free radical scavengers. These WSe₂ dots in ultrasmall size show rapid renal clearance of ≈74% injection dose via urine excretion in 24 h and do not cause any apparent toxicity in vivo for up to 30 d.     

Effects of hydroxyapatite nanoparticles on proliferation and apoptosis of human breast cancer cells (MCF-7)

The study aimed to correlate cell proliferation inhibition with oxidative stress and p53 protein expression in cancerous cells. Hydroxyapatite (HAP) (Ca₁₀(PO₄)₆(OH)₂) is the essential component of inorganic composition in human bone. It has been found to have obvious inhibitory function on growth of many kinds of tumor cells and its nanoparticle has stronger anti-cancerous effect than macromolecule microparticles. Human breast cancer cells (MCF-7) were cultured and treated with HAP nanoparticles at various concentrations. Cells viability was detected with MTT colorimetric assay. The morphology of the cancerous cells was performed by transmission electron microscopy and the expression of a cell apoptosis related gene (p53) was determined by ELISA assay and flow cytometry (FCM). The intracellular reactive oxygen species (ROS) level in HAP exposed cells was measured by H₂DCFDA staining. DNA damage was measured by single-cell gel electrophoresis assay. The statistical analysis was done by one way ANOVA. The cellular proliferation inhibition rate was significantly (p < 0.05) increasing in a dose-dependent manner of HAP nanoparticles. Cell apoptotic characters were observed after MCF-7 cells were treated by HAP nanoparticles for 48 h. Moreover, ELISA assay and FCM shows a dose-dependent activation of p53 in MCF-7 cells treated with nanoHAP. These causative factors of the above results may be justified by an overproduction of ROS. In this study, a significant (p < 0.05) increase in the level of intracellular ROS in HAP-treated cells was observed. This study shows that HAP inhibits the growth of human breast cancer MCF-7 cells as well as induces cell apoptosis. This study shows that HAP NPs Induce the production of intracellular reactive oxygen species and activate p53, which may be responsible for DNA damage and cell apoptosis.     

Synthesis and structural investigation of ferrofluids with porphyrins and prospects of their application in photodynamic therapy

Complexes of superparamagnetic nanoparticles of magnetite with porphyrins, i.e., sulfonated tetraphenylporphine dihydrochloride (H₂TPPS₄(HCl)₂) and photodithazine (used in photodynamic therapy for treatment of oncological diseases), in an aqueous medium have been synthesized for the first time and investigated using small-angle neutron scattering and spectrophotometry. The influence of the biocompatible polymer Pluronic on the functional properties of the synthesized complexes has also been analyzed. It has been shown that the synthesized complexes of ferrofluids with photodithazine and Pluronic exhibit a high efficiency as compounds capable of suppressing the reproduction of tumor cell cultures. The results obtained can be used in the design of a magnetically guided drug for photodynamic therapy.     

A new approach to the drug release kinetics of a discrete system: SiO2 system obtained by ultrasonic dry spraying

Mesoporous silica materials have already proved to be non-toxic and biocompatible, and also to have large pore volume and very high specific surface area suitable for loading of small molecules. Having this in mind and the fact that silicon dioxide (SiO₂) powders can be so designed to obtain particle structures organized at multi levels, SiO₂ was chosen as a potential carrier for metronidazole, an antibiotic drug. SiO₂ powder was synthesized in two stages: first silica sol was prepared by hydrothermal synthesis and second the sol was converted into powder by dry spraying with simultaneous incorporation of the antibiotic into its structure. Scanning and transmission electron microscopy study revealed very complex structure and sub-structure of SiO₂ particles. Cell viability tests were used for estimation of cytotoxicity of so synthesized SiO₂. The drug release data showed that the system can provide drug release for a long time. Also, the device behavior is fully predictable, according to our theoretical model of multilevel structure design, and gives many opportunities for model investigations of drug release and its kinetics. The pore sizes and their distribution were observed as a limiting factor of drug release kinetics. Therefore, as the pore sizes are given as a set of discrete values, the kinetics of drug release might also be given as a set of corresponding discrete values.     

ROS enhancement by silicon nanoparticles in X-ray irradiated aqueous suspensions and in glioma C6 cells

The capability of silicon nanoparticles to increase the yield of reactive species upon 4 MeV X-ray irradiation of aqueous suspensions and C6 glioma cell cultures was investigated. ROS generation was detected and quantified using several specific probes. The particles were characterized by FTIR, XPS, TEM, DLS, luminescence, and adsorption spectroscopy before and after irradiation to evaluate the effect of high energy radiation on their structure. The total concentration of O₂ ^•−/HO₂ ^•, HO^•, and H₂O₂ generated upon 4-MeV X-ray irradiation of 6.4 μM silicon nanoparticle aqueous suspensions were on the order of 10 μM per Gy, ten times higher than that obtained in similar experiments but in the absence of particles. Cytotoxic ¹O₂ was generated only in irradiation experiments containing the particles. The particle surface became oxidized to SiO₂ and the luminescence yield reduced with the irradiation dose. Changes in the surface morphology did not affect, within the experimental error, the yields of ROS generated per Gy. X-ray irradiation of glioma C6 cell cultures with incorporated silicon nanoparticles showed a marked production of ROS proportional to the radiation dose received. In the absence of nanoparticles, the cells showed no irradiation-enhanced ROS generation. The obtained results indicate that silicon nanoparticles of <5 nm size have the potential to be used as radiosensitizers for improving the outcomes of cancer radiotherapy. Their capability of producing ¹O₂ upon X-ray irradiation opens novel approaches in the design of therapy strategies.     

Some new 4‐coordinated nanostructure cadmium imidazolidine Schiff base complexes: Thermal behavior,antimicrobial, and DNA cleavage potential

In this study, a new series of cadmium halide/pseudohalide complexes with a novel Schiff base ligand containing imidazolidine ring has been successfully synthesized. The structure of the ligand and its complexes was characterized by analysis tools such as Fourier transform infrared, UV‐visible, proton and carbon nuclear magnetic resonance spectra, molar conductance, and thermal analysis. Also cadmium bromide and iodide nanostructure complexes have been prepared via sonochemical method. X‐ray powder diffraction and scanning electron microscopy techniques confirmed nanostructure sheets for these 2 cadmium complexes. All the newly prepared compounds were screened for their antimicrobial activities, against 4 bacterial and 2 fungal strains using disk diffusion and serial dilution methods. The CdL(N₃)₂ and CdLCl₂ complexes showed the best antimicrobial activity as compared with other compounds. Moreover, DNA cleavage potential of all compounds was investigated by agarose gel electrophoresis method. The results showed remarkable ability of some cadmium complexes for DNA cleavage. Furthermore, thermal behaviors of all cadmium complexes were studied in the range of room temperature to 800°C under nitrogen atmosphere. The complexes were thermally decomposed via 2 to 4 steps. Cadmium metal was suggested as final residue at the end of thermal decomposition process.     

Physalis angulata induces death of promastigotes and amastigotes of Leishmania (Leishmania) amazonensis via the generation of reactive oxygen species

Leishmaniasis are a neglected group of emerging diseases that have been found in 98 countries and are caused by protozoa of the genus Leishmania. The therapy for leishmaniasis causes several side effects and leads to drug-resistant strains. Natural products from plants have exhibited activities against Leishmania in various experimental models. Physalis angulata is a widely used plant in popular medicine, and in the literature it has well-documented leishmanicidal activity. However, its mechanism of action is still unknown. Thus, this study aims to evaluate the mechanism driving the leishmanicidal activity of an aqueous extract of P. angulata root (AEPa). AEPa was effective against both promastigotes and intracellular amastigote forms of Leishmania amazonensis. This effect was mediated by an increase of reactive oxygen species (ROS), but not of nitric oxide (NO). The increased production of ROS induces cell death by phenotypes seems by apoptosis cell death in Leishmania, but not autophagy or necrosis. In addition, morphological analysis of macrophages showed that AEPa induced a high number of cytoplasmic projections, increased the volume of cytoplasm and number of vacuoles, caused cytoskeleton alterations and resulted in high spreading ability. AEPa also promoted superoxide anion (O₂⁻) production in both uninfected macrophages and those infected with Leishmania. Therefore, these results revealed that AEPa causes cell death by phenotypes seems by apoptosis cell death in L. amazonensis and modulates macrophage activation through morphofunctional alterations and O₂⁻ generation to induce Leishmania death.     

Encapsulating Tin Dioxide@Porous Carbon in Carbon Tubes: A Fiber‐in‐Tube Hierarchical Nanostructure for Superior Capacity and Long‐Life Lithium Storage

A novel fiber‐in‐tube hierarchical nanostructure of SnO₂@porous carbon in carbon tubes (SnO₂@PC/CTs) is creatively designed and synthesized though a carbon coating on scalable electrospun hybrid nanofibers template and a post‐etching technique. This 1D nanoarchitecture consists of double carbon‐buffering matrixes, i.e., the external carbon tubular shell and the internal porous carbon skeleton, which can work synergistically to address the various issues of SnO₂ nanoanode operation, such as pulverization, particle aggregation, and vulnerable electrical contacts between the SnO₂ nanoparticles and the carbon conductors. Thus, the as‐obtained SnO₂@PC/CTs nanohybrids used as a lithium‐ion‐battery anode exhibits a higher reversible capacity of 1045 mA h g^?1 at 0.5 A g^?1 after 300 cycles as well as a high‐rate cycling stability after 1000 cycles. The enhanced performance can be attributed to the wonderful merits of the external carbon protective shell for preserving the integrity of the overall electrode, and the internal porous carbon skeleton for inhibiting the aggregation and electrical isolation of the active particles during cycling.