Cu 7,7,8,8-tetracyanoquinodimethane (CuTCNQ) may be chemically synthesized in two phases, one of which is significantly more conductive (phase I) than the other (phase II). Because CuTCNQ is sparingly soluble in acetonitrile, reduction of TCNQ to <mml:math display="inline"><mml:mrow><mml:msup><mml:mi>TCNQ</mml:mi><mml:mrow><mml:mi>•</mml:mi><mml:mo>−</mml:mo></mml:mrow></mml:msup></mml:mrow></mml:math>TCNQ•− in the presence of <mml:math display="inline"><mml:mrow><mml:msubsup><mml:mi>Cu</mml:mi><mml:mrow><mml:mo>(</mml:mo><mml:mi>MeCN</mml:mi><mml:mo>)</mml:mo></mml:mrow><mml:mo>+</mml:mo></mml:msubsup></mml:mrow></mml:math>Cu(MeCN)+ under conditions where the solubility is exceeded in this solvent allows CuTCNQ nucleation-growth processes to occur at defect sites on carbon, gold, and platinum macro- and microdisk electrode surfaces. Rapid growth of large branched needle-shaped phase I crystals occurs on the time scale of cyclic voltammetry at semiconducting CuTCNQ nucleation sites. Infrared spectra and the crystal morphology detected by electron microscopy of electrocrystallized solid, are all consistent with growth of purely phase I CuTCNQ solid. The smaller crystals formed on the electrode surface, but not larger ones, may be stripped from the electrode surface by application of positive potentials. Mechanistic aspects of the electrocrystallization and stripping processes are considered.

Background: Regenerative medicine has the potential to treat genetic disorders and replace damaged or missing tissue. The use of donor or animal tissue raises many well-known issues, including limited tissue availability, the possibility of rejection and patient infection. Stem cell therapy raised hope of overcoming these issues, but created new risks including tumour formation and limited benefit if the desired target tissue does not form. The recent development of 3-dimensional tissues, including organoids, allows the creation of more complex tissues for personalised regenerative medicine. Methods: This article details the potential health risks of 3-dimensional organoid and tissue therapy versus dissociated stem cell therapy. The current ethical and regulatory issues surrounding 3-dimensional organoid and tissue therapy are presented with a focus on the highly influential FDA and International Society of Stem Cell Research (ISSCR) guidelines. Conclusions: The potential use of 3-dimensional organoid and tissue therapy may deliver greater patient benefits than other regenerative medicine approaches, but raises new health and ethical risks. Preclinical testing of these therapies will not mitigate some of their risks; they may only be understood after first-in-human trials. The potential irreversibility and high risk of these therapies affects how clinical trials should be structured, including post-trial care for participants.

An analytical solution to impedance allows correlation of an effective electrode area with the impedance and phase angle at low frequencies.

The impact of protein fouling on platinum electrodes was assessed by electrochemical methods. Protein fouling affected the electrode potential and charge transfer through the electrode‐solution interface. Adsorbed proteins partially blocked the electrode, with no charge passing through blocked regions. The electrochemical theory and methodology for investigating partially blocked electrodes is fully presented, applied to protein adsorption, and the implications for bionics applications are discussed. The partially blocked electrode had a reduced admittance, and increased impedance and polarization resistance consistent with a smaller effective electrode area. The charge storage capacity and charge injection capacity decreased after protein adsorption. The effective electrode area was assessed by impedance and cyclic voltammetry. The diffusion profile towards the partially blocked electrode was mixed between linear and radial diffusion.

Electrodes are used in vivo for chemical sensing, electrophysiological recording, and stimulation of tissue. The electrode configuration used in vivo is often optimised for a specific anatomy and biological or clinical outcomes, not electrochemical performance. Electrode materials and geometries are constrained by biostability and biocompatibility issues and may be required to function clinically for decades. We performed benchtop electrochemistry, with changes in reference electrode, smaller counter-electrode sizes, and three- or two-electrode configurations. We detail the effects different electrode configurations have on typical electroanalytical techniques used on implanted electrodes. Changes in reference electrode required correction by application of an offset potential. In a two-electrode configuration with similar working and reference/counter-electrode sizes, the electrochemical response was dictated by the rate-limiting charge transfer step at either electrode. This could invalidate calibration curves, standard analytical methods, and equations, and prevent use of commercial simulation software. We provide methods for determining if an electrode configuration is affecting the in vivo electrochemical response. We recommend sufficient details be provided in experimental sections on electronics, electrode configuration, and their calibration to justify results and discussion. In conclusion, the experimental limitations of performing in vivo electrochemistry may dictate what types of measurements and analyses are possible, such as obtaining relative rather than absolute measurements.