A cationic amino acid polymer nanocarrier synthesized in supercritical CO2 for co-delivery of drug and gene to cervical cancer cells.

The present study was undertaken to investigate the ability of a drug curcumin-loaded polymer to inhibit the growth of cervical cancer cells by enhancing the anti-cancer efficiency of curcumin. We synthesized poly(methacryloyl beta-alanine) (PMBA) as a nanocarrier by radical polymerization in supercritical CO2. The results showed that the curcumin encapsulated and folic acid (FA)-treated PMBA (Poly@Cur-FA) for 24 h activated the reactive oxygen species-mediated programmed cell death machinery in HeLa cells. This remarkable effect of Poly@Cur-FA treatment was visualized using different fluorescent probes, which demonstrated that the Poly@Cur-FA treatment disrupted the cell membrane, as also supported by scanning electron microscopy observations. The effect of Poly@Cur-FA dispersion on the cells was observed under a transmission electron microscope. Further, the HeLa cells were treated with the polymer encapsulated curcumin and Bcl2 siRNA (Pol-Cur-siRNA) for 24 h, which effectively suppressed the Bcl2 and simulated the autophagic pathway. This co-delivery system was designed to inhibit curcumin efflux and can enhance the treatment efficacy by targeting multiple signaling pathways, including cell cycle, apoptotic, and autophagic pathways. Collectively, the Pol-Cur-siRNA system appears to offer an efficient combinational therapeutic strategy that might overcome the problems associated with the chemosensitivity against the standard synthetic anti-cancer drugs. To support the experimental data, an artificial neural network model was developed to foresee the drug and gene release behaviors.

Graphitic carbon nitride/NH2-MIL-101(Fe) composite for environmental remediation: Visible-light-assisted photocatalytic degradation of acetaminophen and reduction of hexavalent chromium.

Herein, an efficient photocatalyst composed of graphitic carbon nitrate and iron-based metal-organic framework (g-C3N4/NH2-MIL-101(Fe)) composite was fabricated by a solvothermal method for the degradation of acetaminophen (AAP) and reduction of Cr(VI) under sunlight illumination. The composite was confirmed by X-ray diffraction. UV-visible spectra showed that the bare g-C3N4, pure Fe-MOF, and composite harvest solar light effectively. The photocatalytic experiment indicated that the composite exhibited superior reduction efficiency of Cr(VI) (66%) compared to the bare g-C3N4 (35%) and pure Fe-MOF (51%) at pH 7. As the pH decreases from 9 to 2, the reduction efficiency increased. The highest Cr(VI) reduction (91%) was observed at pH 2. On the other hand, the catalyst degraded 94% of AAP at pH 7 compared to the bare g-C3N4 (42%) and pure Fe-MOF (60%) in the presence of hydrogen peroxide. A radical scavenger experiment endorsed that the generation of superoxide radicals was the main reason for the AAP degradation. The cyclic stability test indicated that there was no substantial decrease in the degradation efficiency of AAP after ten repeated cycles. The kinetic studies showed that the photodegradation of AAP and reduction Cr(VI) was well-fitted to the first-order kinetics. Gas chromatography-mass spectrometry analysis showed that hydroquinone, aliphatic carboxylic acids, monohydroxy, and dihydroxy paracetamol were the main products formed as a result of such degradation process. Therefore, the iron-based MOF and their composites can be used as effective photocatalysts for pollutants degradation.

Metal-organic frameworks with different oxidation states of metal nodes and aminoterephthalic acid ligand for degradation of Rhodamine B under solar light.

Metal-organic frameworks (MOFs) have been investigated recently as effective visible light photocatalysts. In this report, we synthesized nickel, iron, and titanium-based MOFs with different oxidation states of metal ions and aminoterephthalic acid ligand for photocatalytic degradation of Rhodamine B (RhB) dye under solar light irradiation. The photoluminescence analysis revealed that the Fe-MOF could suppress the recombination of photoinduced charges and effectively degrade the dye. The photocatalytic experiment demonstrated that the Fe-MOF exhibited higher degradation efficiency of dye (90 %) compared to the Ni-MOF (9 %) and Ti-MOF (50 %) at pH 7 in 90 min. In addition, the effects of catalyst amount, dye concentration, and solution pH on dye degradation were investigated. The photodegradation of dye using Fe-MOF was well-fitted to the first-order kinetics with an R2 value of 0.9987. Furthermore, reactive oxygen species test and electron paramagnetic resonance study revealed that the superoxide anion radicals were mainly responsible for the dye degradation. Cyclic test analysis indicates that there was no substantial decrease in the degradation efficiency of dye after four consecutive cycles.

Highly sensitive amperometric detection of glutamate by glutamic oxidase immobilized Pt nanoparticle decorated multiwalled carbon nanotubes(MWCNTs)/polypyrrole composite.

A highly sensitive and selective glutamate biosensor using glutamate Oxidase (GlUtOx) immobilized platinum nanoparticle (PtNP) decorated multiwall carbon nanotube (MWCNTs)/polypyrrole (PPy) composite on glassy carbon electrodes (GC) is demonstrated. PtNP decorated MWCNTs (Pt-MWCNTs), PPy and Pt-MWCNTs/PPy composite were characterized by Field Emission Scanning Electron Microscope (FESEM), X-ray diffraction (XRD) and Raman analysis to confirm the formation of the nanocomposite. The glutamate Oxidase (GlUtOx) was immobilized on a GC/Pt-MWCNTs/PPy and characterized by the cyclic voltammetry (CV) and impedance spectroscopy (EIS) analysis. The fabricated L-glutamate biosensor exhibited high sensitivity (723.08 µA cm-2 mM-1) with less response time (3 s) with a detection limit of 0.88 µM. The dynamic range from 10 to 100 µM with a correlation coefficient (R2) of 0.985 was observed for the L-glutamate biosensor. The analytical recovery of added L-glutamate acid (50 and 100 µM) in human serum soup were 96.1% and 97.5% respectively. The enzyme immobilized GC/Pt-MWCNTs/PPy/GlUtOx bioelectrode lost 12.6% and 23.8% of its initial activity after 30 days when stored at - 20 °C and 4 °C respectively.

Facile construction of vertically aligned ZnO nanorod/PEDOT:PSS hybrid heterojunction-based ultraviolet light sensors: efficient performance and mechanism.

We demonstrate a simple, planar manufacturing process-compatible fabrication of highly efficient UV sensors based on a hybrid heterojunction of an array of vertically aligned ZnO nanorods (NRs) and PEDOT: PSS. The ZnO NR array was grown by the solution growth process and the aspect ratio (length 1 to 4 µm, diameter ∼80 nm) of the rods was controlled by varying the growth time. UV sensors based on (i) naked ZnO NRs and (ii) ZnO NR/PEDOT:PSS heterojunctions were fabricated and tested. The UV sensitivity of bare ZnO NRs was found to increase with increasing aspect ratio of the NRs due to the increase in the photogenerated charge carriers as the fraction of material interacting with the light increases. Under 5 V bias, naked ZnO NR arrays showed a photocurrent of 8.84 × 10(-5) A, a responsivity of 0.538 A W(-1) and a sensitivity of 4.80 under UV (λ = 256 nm, 130 µW) illumination. ZnO NR/PEDOT:PSS hybrid heterojunctions showed diode-like behavior with a leakage current less than 2.54 × 10(-8) A at -5 V and forward turn-on voltage of 1.1 V. ZnO NR/polymer-based hybrid heterojunctions show a photocurrent of 6.74 × 10(-4) A, responsivity of 5.046 A W(-1) and excellent sensitivity of 37.65 under UV (λ = 256 nm, 130 µW) illumination. Compared with bare ZnO NR arrays, the ZnO NR/polymer heterojunction device shows responsivity enhanced by a factor of 10, sensitivity enhanced by a factor of 8 and faster rise and decay time. The enhanced performance may be due to effective charge separation guided by the built-in potential formed at the interface between ZnO NRs and PEDOT: PSS.

Photocatalytic degradation of endocrine disruptor Bisphenol-A in the presence of prepared CexZn1-xO nanocomposites under irradiation of sunlight.

Photocatalytic degradation of Bisphenol A (BPA), a representative endocrine disruptor chemical, was carried out under irradiation of sunlight in the presence of CexZn1-xO nanophotocatalyst. Cerium (Ce) ions were successfully incorporated into the bulk lattice of ZnO by simple co-precipitation process. The CexZn1-xO composite nanostructures exhibited higher photocatalytic efficiency than pure ZnO in the degradation of BPA under sunlight irradiation and nearly complete mineralization of BPA was achieved. The degradation rate was strongly dependent on factors such as the size and structure of catalyst, doping material concentration, BPA concentration, catalyst load, irradiation time and pH levels. This work suggested that the CexZn1-xO assisted photocatalytic degradation is a versatile, economic, environmentally benign and efficient method for BPA removal in the aqueous environment.

On the suitability of carbon nanotube forests as non-stick surfaces for nanomanipulation.

A carbon nanotube forest provides a unique non-stick surface for nanomanipulation, as the nanostructuring of the surface allows micro- and nanoscale objects to be easily removed after first being deposited via a liquid dispersion. A common problem for smooth surfaces is the strong initial stiction caused by adhesion forces after deposition onto the surface. In this work, carbon nanotube forests fabricated by plasma-enhanced chemical vapour deposition are compared to structures with a similar morphology, silicon nanograss, defined by anisotropic reactive ion-etching. While manipulation experiments with latex microbeads on structured as well as smooth surfaces (gold, silicon, silicon dioxide, Teflon, diamond-like carbon) showed a very low initial stiction for both carbon nanotube forests and silicon nanograss, a homogeneous distribution of particles was significantly easier to achieve on the carbon nanotube forests. Contact-angle measurements during gradual evaporation revealed that the silicon nanograss was superhydrophic with no contact-line pinning, while carbon nanotube forests in contrast showed strong contact-line pinning, as confirmed by environmental scanning electron microscopy of microdroplets. As a consequence, latex microbeads dispersed on the surface from an aqueous solution distributed evenly on carbon nanotube forests, but formed large agglomerates after evaporation on silicon nanograss. Lateral manipulation of latex microbeads with a microcantilever was found to be easier on carbon nanotube forests and silicon nanograss compared to smooth diamond-like carbon, due to a substantially lower initial stiction force on surfaces with nanoscale roughness. Nanomanipulation of bismuth nanowires, carbon nanotubes and organic nanofibres was demonstrated on carbon nanotube forests using a sharp tungsten tip. We find that the reason for the remarkable suitability of carbon nanotube forests as a non-stick surface for nanomanipulation is indeed the strong contact-line pinning in combination with the nanostructured surface, which allows homogeneous dispersion and easy manipulation of individual particles.