The photosynthetic reaction center (RC) is an integral membrane protein that, upon absorption of photons, generates a hole-electron couple with a yield close to one. This energetic state has numerous possible applications in several biotechnological fields given that its lifetime is long enough to allow non-metabolic ancillary redox chemistry to take place. Here we focus on RCs reconstituted in liposomes, formed with sole phospholipids or in blends with other lipids, and show that the electrical charge sitting on the polar head of such hydrophobic molecules does play an important role on the stability of the hole-electron couple. More specifically this study shows that the presence of negative charges in the surrounding of the protein stabilizes the charge-separated state while positive charges have a strong opposite effect.

Diatoms microalgae represent a natural source of highly porous biosilica shells (frustules) with promising applications in a wide range of technological fields. Functionalization of diatoms’ frustules with tailored luminescent molecules can be envisaged as a convenient, scalable biotechnological route to new light emitting silica nanostructured materials. Here we report a straightforward protocol for the in vivo modification of Thalassiosira weissflogii diatoms’ frustules with a red emitting organic dye based on thienyl, benzothiadiazolyl and phenyl units. The metabolic insertion of the dye molecules into the diatoms shells, combined with an acidic-oxidative isolation protocol of the resulting dye stained biosilica, represents a novel strategy to develop highly porous luminescent biosilica nanostructures with promising applications in photonics.

An efficient enzymatic route for the synthesis of conducting oligomer of substituted aniline complexed with poly(sodium 4-styrenesulfonate) is presented. This polyelectrolyte assisted horseradish peroxidase catalyzed oligomerization of ortho-toluidine provides a route to synthesize water-soluble, highly conductive oligomers under acidic conditions. The UV-Vis, FTIR, thin film conductivity, molecular weight assessment and modeling studies of the oligomer/polymer complex indicate the presence of a thermally stable and electroactive oligomer with extended conjugation that was not present in similar conductive polymers (e.g. PANI). Moreover, the use of water-soluble templates provide a unique combination of properties such as high conductivity and processability. The same procedure was also implemented for the polymerization of 2,6-xylidine: however, the reaction did not occur suggesting a much more complex stereo-specificity of the enzymatic polymerization. Modeling studies were used to explain this behavior. The conductive poly(ortho-toluidine) can be used in chemiresistive sensors for the detection of humidity.

This work decribes the enhancement of the electrical figures of merit of an Electrolyte Gated Thin-Film Transistor (EG-TFT) comprising a nanocomposite of n-type tungsten disulfide (WS2) nanotubes (NTs) dispersed in a regio-regular p-type poly(3-hexylthiophene-2,5-diyl) (P3HT) polymeric matrix. P3HT/WS2 nanocomposites loaded with different concentrations of NTs, serving as EG-TFTs electronic channel materials have been studied and the formulation has been optimized. The resulting EG-TFTs figures of merit (field-effect mobility, threshold voltage and on-off ratio) are compared with those of the device comprising a bare P3HT semiconducting layer. The optimized P3HT/WS2 nanocomposite, comprising a 60% by weight of NTs, results in an improvement of all the elicited figures of merit with a striking ten-fold increase in the field-effect mobility and the on/off ratio along with a sizable enhancement of the in-water operational stability of the device.

In this work, we report on fabrication of the thin-films of silicon oxide dielectric layers on silicon with back-side contact and utilization of the structure to study the detection of human Troponin antigen (cTnI) molecules: the cardiac biomarkers for the early diagnosis of acute myocardial infraction. Aptamers are selectively bound to the target molecules and can block the binding epitope for further reaction like immobilization or interaction to any other molecules. In contrast to antibodies, the aptamers are smaller in size, which allows target molecules to be brought closer to the surface of the biosensor and, therefore, to enhance the molecular signal. The target molecule in this work is cTnI, which is located in the cardiac muscle tissue. As a reliable indicator of heart failure and injury, it is specifically considered for the diagnosis of myocardial infarctions. The solutions of Troponin molecules were studied in different concentrations range from 10 pg/μL to 1 ng/μL. For the electrical detection of cTnI, we used the field-effect capacitive electrolyte-insulator-semiconductor (EIS) technique, which is a robust method for the quantitative characterization of molecular layers. The measured values of capacitances and flat band voltages were used to acquire information about the properties of the molecular layers obtained using solutions with different troponin concentrations. It was shown that this method demonstrates high sensitivity to target cardiac biomolecules and opens up new perspectives for highly selective and sensitive cardiac biosensors developed on the basis of silicon nanowire structures.

Electroactive conducting polymers are suitable for soft actuators (artificial muscles). The actuation is induced by electrochemical oxidation of conducting polymer (film) in an electrolyte solution, due to insertion of bulky counter ions (dopant ions). The magnitude of deformation (strain) depends on the size of dopant ions and the degree of oxidation. It is worthwhile to know the relationship between the magnitudes of deformation and ion size. An electrodeposited Polypyrrole film was electrochemically cycled in aqueous electrolytes of NaCl, NaBr, NaNO3, NaBF4 and NaClO4. The strain of film during electrochemical oxidation and reduction was precisely measured using a laser displacement meter and a handmade apparatus. From the strain and electrical charges inserted in the film during oxidation, the volumes and radii of dopant ions were estimated, assuming the isotropic expansion of the film. The estimated anion radii of Cl-, Br-, NO3-, BF4- and ClO4- were 235, 246, 250, 270 and 290, respectively. The results were discussed taking the crystallographic and hydrated ion radii in literatures into consideration.

This paper introduces preliminary work on a UV-curable, environmentally benign and degradable elastomer, poly(glycerol sebacate itaconate), or PGSI, for use in soft robotics. A one-pot, solvent-free synthesis route using safe and inexpensive chemical reagents was developed to enable easy adoption into soft robotics labs. Material characterization of non-aged PGSI samples gave: ultimate tensile strength (UTS) ranging from 134 to 193 kPa with moduli ranging from 57 to 131 kPa and elongations at break ranging from 105 to 137 % (12 samples from 6 batches tested), and resilience values ranging from 73 to 82 % (3 samples from 3 batches tested). FTIR analysis showed a possible decrease in carbon-carbon double bonds after UV curing, evidencing a decrease in itaconic acid methylene groups from photoinitiated free radical cross-linking. NMR on the pre-polymer suggested incorporation of itaconic acid into the main polymer chain and evidence of heterogeneity of the polymer backbone resulting from glycerol bonding. An example molded soft pocket pneumatic actuator is created and briefly characterized. With further development, PGSI can be a degradable material to incorporate into temporary soft robots.