a b s t r a c tReproducible electrodeposition of adherent and homogeneous polypyrrole was achieved on copper from a salicylate solution. The process was facilitated by the formation of a passive layer which inhibited further dissolution of copper but was sufficiently conducting to allow electropolymerisation. The deposited polymer adopted the characteristic cauliflower morphology. The corrosion protection properties of the coating were assessed using polarisation plots, Tafel analysis, OCP measurements and electrochemical impedance spectroscopy in 0.1 and 0.6 M (3.5% w/v) NaCl solutions. The polymer coating was effective in protecting copper and was stable for periods exceeding 2 weeks of immersion in 0.6 M NaCl.

Despite advances in intracellular delivery technologies, efficient methods are still required that are vector-free, can address a wide range of cargo types and can be applied to cells that are difficult to transfect whilst maintaining cell viability. We have developed a novel vector-free method that uses reversible permeabilization to achieve rapid intracellular delivery of cargos with varying composition, properties and size. A permeabilizing delivery solution was developed that contains a low level of ethanol as the permeabilizing agent. Reversal of cell permeabilization is achieved by temporally and volumetrically controlling the contact of the target cells with this solution. Cells are seeded in conventional multi-well plates. Following removal of the supernatant, the cargo is mixed with the delivery solution and applied directly to the cells using an atomizer. After a short incubation period, permeabilization is halted by incubating the cells in a phosphate buffer saline solution that dilutes the ethanol and is non-toxic to the permeabilized cells. Normal culture medium is then added. The procedure lasts less than 5 min. With this method, proteins, mRNA, plasmid DNA and other molecules have been delivered to a variety of cell types, including primary cells, with low toxicity and cargo functionality has been confirmed in proof-of-principle studies. Co-delivery of different cargo types has also been demonstrated. Importantly, delivery occurs by diffusion directly into the cytoplasm in an endocytic-independent manner. Unlike some other vector-free methods, adherent cells are addressed in situ without the need for detachment from their substratum. The method has also been adapted to address suspension cells. This delivery method is gentle yet highly reproducible, compatible with high throughput and automated cell-based assays and has the potential to enable a broad range of research, drug discovery and clinical applications.

Metallic copper nanoparticles (CuNP) are formed from the reduction of hierarchical copper-based micro/nanostructures previously electrodeposited on polypyrrole-polystyrene sulfonate (PPy-PSS) thin films. The application of a high reduction potential causes the erosion of the micro/nanostructures nanosheets and the formation of CuNP. The CuNP are used in a series of preliminary tests in order to assess their performance in the sensing of nitrate. The sensing performance is improved with the introduction of polyethyleneimine-functionalized multiwall carbon nanotubes (MWNT-PEI) to the PPy-PSS films. Electrochemical impedance spectroscopy studies show that the nanotubes increased the electronic conductivity of the reduced films. The limit of detection of the PPy-PSS-MWNT-PEI-CuNP nanocomposite is 30 mM nitrate. The materials need further development and optimization work in order to be applied as sensors.

Pyrrole was electropolymerised in a 0.01 M sulfonated βÀcyclodextrin solution to generate an adherent polypyrrole film doped with the anionic sulfonated βÀcyclodextrin, PPyÀSβCD. This polymeric material was used as an electrochemical sensor for the detection of dopamine (DA), and compared with the sensing abilities of polypyrrole doped with several more common anionic dopants. The sensing performance of the PPyÀSβCD film was significantly better, with a linear calibration curve extending to 50 μM, with a sensitivity of 0.90 μA μM À1 cm À2 and a detection limit of 1.0  10 À6 M. Excellent selectivity was achieved and no interference was observed from a range of interference compounds, including ascorbic acid, uric acid, aspartic acid, acetylcholine, aminobutyric acid, glutamic acid, glycine, histamine, acetaminophenol 5Àhydroxytryptamine and 5Àhydroxyindole acetic acid. However, interference was seen with the structurallyÀrelated epinephrine (Ep) and 3,4Àdihydroxyphenylacetic acid (DOPAC), with the oxidation of DA, Ep and DOPAC occurring at similar potentials. The good selectivity in the presence of the other interference species was attributed to an interaction between the cyclodextrin dopant and the protonated DA molecule which was evident when data were fitted to MichaelisÀMenten and LineweaverÀBurk kinetics.

The electrochemistry of methyl, ethyl and benzyl viologens was studied at polypyrrole doped with sulfonated cyclodextrin, PPysβ-CD, a cation exchange polymer. Three reduction waves were observed corresponding to the reduction of the viologen (V 2+ ) to the radical cation (V •+ ) followed by the neutral compound (V 0 ) and a third intense peak. This third reduction peak was associated with the ingress of V 2+ as the PPysβ-CD film is reduced. As the incorporated V 2+ is reduced to the neutral viologen, the influx of more V 2+ occurs to achieve charge balance and this repeated influx and reduction of V 2+ gives an intense reduction wave. These processes were only observed with sβ-CD as a dopant and this was attributed to the formation of an ion pair between the anionic cyclodextrin and the viologen. Lower diffusion coefficients and rate constants were observed for the reduction of V 2+ and V •+ on adding an excess of sβ-CD to the viologen solution. Linear calibration curves were obtained extending from 1.0 μM to 80 μM when the PPysβ-CD was employed as a sensor for methyl viologen. While the PPysβ-CD is not suitable for the detection of low nM concentrations, the uptake and extraction of MV 2+ was observed on polarising the PPysβ-CD in a solution of the viologen, highlighting the dual action of the polymer.