Biocompatible and flexible graphene oxide/upconversion nanoparticle hybrid film for optical pH sensing.

Free-standing optical hybrid film which is composed of positively-charged polyethylenimine-coated NaYF4:Yb,Er nanoparticles and negatively-charged graphene oxide (GO) has been developed to measure pH based on the pH-dependent luminescence quenching effect caused by GO. The isothermal titration calorimetry analyses indicate that the interaction between GO and NaYF4:Yb,Er nanoparticles becomes stronger with increasing pH, leading to a more significant fluorescence quenching of NaYF4:Yb,Er nanoparticles at high pH values. The excellent mechanical properties of the hybrid film endow the thin-film pH sensor with better repeatability and higher stability during the measurements. Quantitatively, the upconversion luminescence intensity of the hybrid film exhibits a linear trend over the pH range of 5.00-8.00. Because of excitation with a 980 nm laser, as expected, the hybrid film sensor is also sensitive to the urine measurements with reduced background absorption. In addition to its good biocompatibility, our free-standing hybrid film sensor would be a promising candidate for biological, medical, and pharmaceutical applications.

Toxicological properties of nanomaterials.

The development of engineered nanomaterials opens tremendous opportunities for their application as therapeutic and diagnostic tools, as well as in the fields of consumer products. As the newly developed material subtype, they exhibit great activities for the high ratio of surface to total atoms. In the bio-system, the activity can render nanomaterials some negative outcomes for their unexpected deposition in organs and cells, the cellular response to the exogenous substance and the interfacial reaction with biomolecules. In this review, we have discussed the evolution of nanotoxicology studies in the past ten years mainly emerging from our laboratory. The early in vivo studies mainly focused on the biokinetic of inhaled nanoparticles and their impacts on mammal tissues, such as the central nervous system, respiratory system, cardiovascular system and so on. Then the scope extended to engineered nanomaterials used as food additives and medicines, as well as their influence on alimentary and reproductive systems. In vitro experiments to study the nanoparticle-cell interaction and nanoparticle-biomolecule interplay are indispensable to reveal the mechanisms behind the macroscopic phenomenon. In addition, novel tools such as new model organisms and synchrotron radiation-based techniques are used to facilitate our understanding of the toxicology profile of nanomaterials.

Comparative bio-effects of SiO2/Gd2O3 nanoparticles depending on their core-shell structures.

Engineered nanoparticles (NPs) can produce negative impacts on human health even in low doses. In this study, Gd2O3 nanoparticles were synthesized via the polyol route and coated with silicon to form particles with different sizes. Although all the SiO2/Gd2O3 NPs did not induce obvious cell death at 10 microg/mL on a macrophage-like cell line (RAW 264.7), their DNA damaging effects, which is measured by single cell gel electrophoresis (SCGE), is prominent in cells treated with the sample with an overall size of 120 nm. Besides, the NPs with core size of 20 nm induced greater damaging effect than NPs with similar total size but core size of 50 nm. Further test applying the modified SCGE with endonuclease III indicated that the DNA damaging effect was greatly associated with oxide pyridine after the treatment. Using immunoblotting, we found that p53 protein is activated and accumulated after the damage occurred. These results provide a new insight into the adverse effect of nanoparticles with core-shell structures, that not only the overall size but the core size of the particles determines their effect in cells.

Variation in the internalization of differently sized nanoparticles induces different DNA-damaging effects on a macrophage cell line.

Although researchers have expended considerable effort on studying the cytotoxicity of nanomaterials, it is possible that there has been insufficient attention paid to their genotoxic potential. Here, we describe a test model that we have developed to evaluate the DNA-damaging effects of negatively charged nanoparticles of different sizes. We compared the DNA damaging effect induced by nanoparticles of various sizes and found that the effect is closely associated with the internalization pattern of the particles. Macrophage cell line RAW 264.7 cells were incubated with carboxylated polystyrene beads (COOH-PBs) ranging in size from 30 to 500 nm. Size-dependent DNA damage was detected, and the lesion induced by two carboxylated fullerene particles confirmed this observation. Confocal microscopy revealed that the entry pathways of these COOH-PBs shifted from direct penetration to endocytosis with increasing particle size, followed by changes in subcellular localization. Subsequent deposition of 30-nm COOH-PBs in the cytosol led to a reduction of Zn²âº and Mg²âº content in the nucleus and an increased p53 level in the whole cell rather than in nucleus, while localization of 50- and 100-nm COOH-PBs in acidic vesicles induced p53 accumulation in both types of extracts. Based on these results, we assume that the damage resulted from a disruption of the balance between DNA damage and repair.

Intrinsic Biotaxi Solution Based on Blood Cell Membrane Cloaking Enables Fullerenol Thrombolysis In Vivo.

We report the construction of blood cell membrane cloaked mesoporous silica nanoparticles for delivery of nanoparticles [fullerenols (Fols)] with fibrinolysis activity which endows the active Fol with successful thrombolysis effect in vivo. In vitro, Fols present excellent fibrinolysis activity, and the Fol with the best fibrinolysis activity is screened based on the correlation between Fols' structure and their fibrinolysis activity. However, the thrombolytic effect in vivo is not satisfactory. To rectify the unsatisfactory situation and avoid the exogenous stimuli, a natural blood cell membrane cloaking strategy with loading the active Fol is chosen to explore as a novel thrombolysis drug. After cloaking, the therapeutic platform prolongs blood circulation time and enhances the targeting effect. Interestingly, compared with platelet membrane cloaking, red blood cell (RBC) membrane cloaking demonstrates stronger affinity with fibrin and more enrichment at the thrombus site. The Fol with RBC cloaking shows quick and efficient thrombolysis efficacy in vivo with less bleeding risk, more excellent blood compatibility, and better biosafety when compared with the clinical drug urokinase (UK). These findings not only validate the blood cell membrane cloaking strategy as an effective platform for Fol delivery on thrombolysis treatment, but also hold a great promising solution for other active nanoparticle deliveries in vivo.

Abscisic acid promotes accumulation of toxin ODAP in relation to free spermine level in grass pea seedlings (Lathyrus sativus L.).

Interrelationship among abscisic acid (ABA) content, accumulation of free polyamines and biosynthesis of beta-N-oxalyl-l-alpha,beta-diaminopropionic acid (ODAP) was studied in grass pea (Lathyrus sativus L.) seedlings under drought stress induced by 10% polyethylene glycol (PEG6000). Increase of ABA content occurred prior to that of ODAP and polyamine contents, and was found significantly positive correlation between ABA content and ODAP content. Addition of exogenous ABA increased ODAP content in leaves. On the other hand, pretreatment with alpha-difluoromethylarginine (DFMA), a polyamine biosynthesis inhibitor, significantly suppressed the accumulation of free putrescine (Put), free spermidine (Spd) and free spermine (Spm), which in turn inhibited biosynthesis of ODAP in well-watered leaves. Meanwhile, addition of exogenous Put alleviated DFMA-induced inhibition on the biosynthesis of Put and Spd, but did not affect the biosynthesis of Spm and ODAP in well-watered leaves. Same result was also achieved in drought-stressed leaves. Increasing accumulation of ODAP was significantly correlated with increasing Spm content (R=0.7957**) but not with that of Spd and Put. Therefore, it can be argued that ABA stimulated the biosynthesis of ODAP simultaneously with increasing the level of free Spm under drought stress condition.

The scavenging of reactive oxygen species and the potential for cell protection by functionalized fullerene materials.

We demonstrated that three different types of water-soluble fullerenes materials can intercept all of the major physiologically relevant ROS. C(60)(C(COOH)(2))(2), C(60)(OH)(22), and Gd@C(82)(OH)(22) can protect cells against H(2)O(2)-induced oxidative damage, stabilize the mitochondrial membrane potential and reduce intracellular ROS production with the following relative potencies: Gd@C(82)(OH)(22)> or =C(60)(OH)(22)>C(60)(C(COOH)(2))(2). Consistent with their cytoprotective abilities, these derivatives can scavenge the stable 2,2-diphenyl-1-picryhydrazyl radical (DPPH), and the reactive oxygen species (ROS) superoxide radical anion (O(2)(*-)), singlet oxygen, and hydroxyl radical (HO(*)), and can also efficiently inhibit lipid peroxidation in vitro. The observed differences in free radical-scavenging capabilities support the hypothesis that both chemical properties, such as surface chemistry induced differences in electron affinity, and physical properties, such as degree of aggregation, influence the biological and biomedical activities of functionalized fullerenes. This represents the first report that different types of fullerene derivatives can scavenge all physiologically relevant ROS. The role of oxidative stress and damage in the etiology and progression of many diseases suggests that these fullerene derivatives may be valuable in vivo cytoprotective and therapeutic agents.