The role of reduced graphene oxide on mitigation of lead phytotoxicity in Triticum aestivum L.plants at morphological and physiological levels.

Rapid global industrialization and an increase in population have enhanced the risk of heavy metals accumulation in plant bodies to disrupt the morphological, biochemical, and physiological processes of plants. To cope with this situation, reduced graphene oxide (rGO) NPs were used first time to mitigate abiotic stresses caused in plant. In this study, rGO NPs were synthesized and reduced with Tecoma stans plant leave extract through modified Hummer's methods. The well prepared rGO NPs were characterized by ultra-violet visible spectroscopy (UV-Vis), Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), Zeta potential, and scanning electron microscopy (SEM). However, pot experiment was conducted with four different concentrations (15, 30, 60, 120 mg/L) of rGO NPs and three different concentrations (300, 500,700 mg/L) of lead (Pb) stress were applied. To observe the mitigative effects of rGO NPs, 30 mg/L of rGO NPs and 700 mg/L of Pb were used in combination. Changes in morphological and biochemical characteristics of wheat plants were observed for both Pb stress and rGO NPs treatments. Pb was found to inhibit the morphological and biochemical characteristics of plants. rGO NPs alone as well as in combination with Pb was found to increase the chlorophyll content of wheat plants. Under Pb stress conditions and rGO NPs treatments, antioxidant enzyme activities like ascorbate peroxidases (APX), superoxide dismutase (SOD), peroxidase (POD) and catalase (CAT) were observed. Current findings revealed that greenly reduced graphene oxide NPs can effectively promote growth in wheat plants under Pb stress by elevating chlorophyll content of leaves, reducing the Pb uptake, and suppressing ROS produced due to Pb toxicity.

Control of graphene aerogel self-assembly in strongly acidic solution via solution polarity tuning.

In view of their advantages (plasticity, low density, adjustable pore size, high porosity of >99.9%), three-dimensional graphene aerogels (GAs) are widely used for energy storage and adsorption separation, which has inspired the development and optimization of the corresponding synthetic techniques. In particular, self-assembly in the liquid phase features the benefits of tunability and sustainability and is viewed as a promising strategy of GA synthesis. During hydrothermal GA preparation, hydrophilic graphene oxide (GO) gradually turns lipophilic upon reduction, and the resulting phase transition separation and polarity change induce self-assembly into an aerogel. However, the effect of solution polarity on the structure or state of dispersed GO nanosheets, which affects the final property-determining process of automatic assembly, is still unclear. Herein, we prepared a series of GAs by hydrothermal reduction of unwashed GO with vitamin C in liquid-phase systems of different polarity and investigated the effects of polarity on the self-assembly process and aerogel properties using a range of instrumental techniques. The results showed that GO reduction is slowed down in weakly polar systems and further demonstrated that the shape of partially reduced graphene oxide (rGO) flakes depends on solution polarity. Flaky, layered, and stacked rGO particles obtained in strongly polar media self-assembled into anisotropic gully aerogels that were brittle and almost completely inelastic. Conversely, in weakly polar media, the prepared rGO sheets were twisted, which increased the number of contact points and modes between sheets and resulted in self-assembly into uniform-pore-structure honeycomb aerogels that showed good elasticity and could be repeatedly compressed.

Nano carriers for drug transport across the blood-brain barrier.

Effective therapy lies in achieving a therapeutic amount of drug to the proper site in the body and then maintaining the desired drug concentration for a sufficient time interval to be clinically effective for treatment. The blood-brain barrier (BBB) hinders most drugs from entering the central nervous system (CNS) from the blood stream, leading to the difficulty of delivering drugs to the brain via the circulatory system for the treatment, diagnosis and prevention of brain diseases. Several brain drug delivery approaches have been developed, such as intracerebral and intracerebroventricular administration, intranasal delivery and blood-to-brain delivery, as a result of transient BBB disruption induced by biological, chemical or physical stimuli such as zonula occludens toxin, mannitol, magnetic heating and ultrasound, but these approaches showed disadvantages of being dangerous, high cost and unsuitability for most brain diseases and drugs. The strategy of vector-mediated blood-to-brain delivery, which involves improving BBB permeability of the drug-carrier conjugate, can minimize side effects, such as being submicrometre objects that behave as a whole unit in terms of their transport and properties, nanomaterials, are promising carrier vehicles for direct drug transport across the intact BBB as a result of their potential to enter the brain capillary endothelial cells by means of normal endocytosis and transcytosis due to their small size, as well as their possibility of being functionalized with multiple copies of the drug molecule of interest. This review provids a concise discussion of nano carriers for drug transport across the intact BBB, various forms of nanomaterials including inorganic/solid lipid/polymeric nanoparticles, nanoemulsions, quantum dots, nanogels, liposomes, micelles, dendrimers, polymersomes and exosomes are critically evaluated, their mechanisms for drug transport across the BBB are reviewed, and the future directions of this area are fully discussed.

[Study on the inclusion complexation interaction of beta-cyclodextrin and beta-carotene by UV-Vis spectra].

Beta-cyclodextrin (beta-CD), a kind of cyclic oligosaccharides, was found to possess a strong inclusion ability with beta-carotene. The inclusion compounds of beta-CD with beta-carotene were prepared by the coprecipitation method, and studied by UV-Vis spectra of different mole ratio beta-CD/beta-carotene in the H2O+ ethanol solution (H2O for beta-CD, and ethanol for beta-carotene). Equilibrium constant of inclusion compound was determined by UV-Vis spectra. The results indicate that 3.25 moles of beta-CD can include one mole beta-carotene to form inclusion compound by Van der Waals force and hydrophobic interaction etc. The optimum synthesis conditions of inclusion compound of beta-CD with beta-carotene is that the mole ratio of beta-CD/beta-carotene is 3.25:1 (mol/mol), the concentration ratio of beta-CD H2O solution/beta-carotene solution is 12:1 (mol x L(-1)/mol x L(-1)), and the time and temperature of inclusion reaction are 2 h and 30 degrees C, respectively. Equilibrium constant of inclusion compound (Ka) is 9.46 x 10(11) L x mol(-1). The selective binding ability of beta-CD with beta-carotene has been discussed from the viewpoint of size/shape-fitting and geometry fitting between the host cavity and the guest molecule. The resistance to oxidation and photooxidation, and the solubility in H2O of beta-carotene were increased by inclusion with beta-CD.