Reorganization Energy upon Controlled Intermolecular Charge-Transfer Reactions in Monolithically Integrated Nanodevices.

Intermolecular electron-transfer reactions are key processes in physics, chemistry, and biology. The electron-transfer rates depend primarily on the system reorganization energy, that is, the energetic cost to rearrange each reactant and its surrounding environment when a charge is transferred. Despite the evident impact of electron-transfer reactions on charge-carrier hopping, well-controlled electronic transport measurements using monolithically integrated electrochemical devices have not successfully measured the reorganization energies to this date. Here, it is shown that self-rolling nanomembrane devices with strain-engineered mechanical properties, on-a-chip monolithic integration, and multi-environment operation features can overcome this challenge. The ongoing advances in nanomembrane-origami technology allow to manufacture the nCap, a nanocapacitor platform, to perform molecular-level charge transport characterization. Thereby, employing nCap, the copper-phthalocyanine (CuPc) reorganization energy is probed, ≈0.93 eV, from temperature-dependent measurements of CuPc nanometer-thick films. Supporting the experimental findings, density functional theory calculations provide the atomistic picture of the measured CuPc charge-transfer reaction. The experimental strategy demonstrated here is a consistent route towards determining the reorganization energy of a system formed by molecules monolithically integrated into electrochemical nanodevices.

Organic Electrochemical Transistors for In Vivo Bioelectronics.

Organic electrochemical transistors (OECTs) are presently a focus of intense research and hold great potential in expanding the horizons of the bioelectronics industry. The notable characteristics of OECTs, including their electrolyte-gating, which offers intimate interfacing with biological environments, and aqueous stability, make them particularly suitable to be operated within a living organism (in vivo). Unlike the existing in vivo bioelectronic devices, mostly based on rigid metal electrodes, OECTs form a soft mechanical contact with the biological milieu and ensure a high signal-to-noise ratio because of their powerful amplification capability. Such features make OECTs particularly desirable for a wide range of in vivo applications, including electrophysiological recordings, neuron stimulation, and neurotransmitter detection, and regulation of plant processes in vivo. In this review, a systematic compilation of the in vivo applications is presented that are addressed by the OECT technology. First, the operating mechanisms, and the device design and materials design principles of OECTs are examined, and then multiple examples are provided from the literature while identifying the unique device properties that enable the application progress. Finally, one critically looks at the future of the OECT technology for in vivo bioelectronic applications.

Edge-driven nanomembrane-based vertical organic transistors showing a multi-sensing capability.

The effective utilization of vertical organic transistors in high current density applications demands further reduction of channel length (given by the thickness of the organic semiconducting layer and typically reported in the 100 nm range) along with the optimization of the source electrode structure. Here we present a viable solution by applying rolled-up metallic nanomembranes as the drain-electrode (which enables the incorporation of few nanometer-thick semiconductor layers) and by lithographically patterning the source-electrode. Our vertical organic transistors operate at ultra-low voltages and demonstrate high current densities (~0.5 A cm-2) that are found to depend directly on the number of source edges, provided the source perforation gap is wider than 250 nm. We anticipate that further optimization of device structure can yield higher current densities (~10 A cm-2). The use of rolled-up drain-electrode also enables sensing of humidity and light which highlights the potential of these devices to advance next-generation sensing technologies.

Bromelain: Methods of Extraction, Purification and Therapeutic Applications

Bromelain is a concoction of sulfhydryl proteolytic enzymes. Depending upon the site of extraction it can be regarded as either stem bromelain (SBM) (EC 3.4.22.32) or fruit bromelain (FBM) (EC 3.4.22.33). Bromelain remain enzymatic active over a broad spectrumand endure a range of pH (5.5 to 8.0) and temperature (35.5 to 71 ºC). It is one of the extensively investigated proteolytic enzyme owing to its astonishing applications in various industries. This necessitated employing a strategy that result in highest purified bromelain in less steps and lowest cost. Use of modernistic approach such as membrane filtration, reverse micellar systems, aqueous two phase extraction and chromatographic techniques have shown promise in this regard. Besides its industrial applications, bromelain has been widely utilized as a potential phytomedical compound. Some of its reported actions include inhibition of platelet aggregation, anti-edematous, anti-thrombotic, anti-inflammatory, modulation of cytokines and immunity, skin debridement and fibrinolytic activity. It also assist digestion, enhance absorption of other drugs and is a potential postoperatively agent that promote wound healing and reduce postsurgical discomfort and swelling.

Performance enhancement of poly(3-hexylthiophene-2,5-diyl) based field effect transistors through surfactant treatment of the poly(vinyl alcohol) gate insulator surface.

We report on the improvement of field effect transistors based on poly(3-hexylthiophene-2,5-diyl) (P3HT) as a channel semiconductor and crosslinked poly(vinyl alcohol) (cr-PVA) as a gate insulator, through the treatment of the cr-PVA film surface before P3HT deposition. We treated the cr-PVA either with hydrochloric acid (HCl) or with a cationic surfactant, hexadecyltrimethylammonium bromide (CTAB), aiming at the passivation of the hole traps at the cr-PVA/P3HT interface. The treatment with HCl leads to an excessive increase in the transistor leakage current and unstable electrical characteristics, despite implying an increase in the gate capacitance. The treatment with CTAB leads to transistors with ca. 50% higher specific capacitance and a tenfold increase in the charge carrier field-effect mobility, when compared to devices based on untreated cr-PVA.