Hematopoietic stem cells (HSCs) are rare cells residing in the bone marrow and give rise to millions of new blood cells daily throughout life. Because of their multipotent, self-renewing nature, they have also been used for several decades to treat hematological disorders. However, HSCs are scarce and difficult to maintain ex vivo, demonstrating the need for developing novel in vitro methods to expand HSCs that mimic the complex in vivo microenvironment in suitable culture tissue plates, in extracellular matrix scaffolds, or on a biochip. One component to include in such an artificial microenvironment is HSC-related growth factors (GFs) immobilized on surfaces that mimic membrane-bound GFs in vivo. In this paper, we have initiated the development of an ex vivo system to study the immobilization of growth factors that sustain HSC maintenance and possibly expansion. However, since HSC-related GFs are expensive we have developed a proof-of-concept model using bovine serum albumin (BSA) as an alternative. Polypyrrole (PPy) was electrochemically synthesized in the presence of dicarboxylic acids with different hydrocarbon chain lengths and polycarboxylic acids with different molecular weights as dopants. BSA was immobilized on the PPy surface using 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide hydrochloride (EDC) and N-hydroxysuccinimide (NHS) to couple BSA to the carboxylic acid dopant of PPy. These PPy films with different dopants showed different abilities to immobilize BSA using EDC/NHS coupling and also different surface properties. In addition, owing to the interesting switchable properties of PPy upon alteration of the oxidation/reduction potential, the immobilized BSA could change its presentation on the PPy surface depending on the redox state. To characterize the PPy surfaces and to study the different immobilization results of BSA on these PPy variants with different dopants and different presentation behavior upon redox switching, the electrochemical properties, hydrophobicity, thickness, roughness, surface COOH density and fluorescence labeling were investigated. The results indicate that the polycarboxylic acid dopants could immobilize more BSA on the PPy surface. Moreover, the BSA in the as-fabricated state shows a "collapsed" presentation on the PPy surface, a "less collapsed" presentation in the oxidized state and an "erected" presentation in the reduced state. Cell viability studies using hematopoietic cells showed that the developed PPy-BSA surfaces did not negatively alter cell viability or cell proliferation compared to the control.

In the domain of organic mixed ionic-electronic conductors (OMIECs), simultaneous transport and coupling of ionic and electronic charges are crucial for the function of electrochemical devices in organic electronics. Understanding conduction mechanisms and chemical reactions in operational devices is pivotal for performance enhancement and is necessary for the informed and systematic development of more promising materials. Surface-enhanced Raman spectroscopy (SERS) is a potent tool for monitoring electrochemical evolution and dynamic doping in operational devices, offering enhanced sensitivity to subtle spectral changes. We demonstrate the utility of SERS for in situ tracking of doping in OMIECs in an organic light-emitting electrochemical cell (LEC) containing a conjugated polymer (poly[2-methoxy-5-(2-ethylhexyloxy)-1,4-phenylenevinylene]; MEH-PPV), a molecular anion (lithium triflate), and an electrolyte network (poly(ethylene oxide); PEO). SERS enhancement is achieved via an interleaved layer of gold particles formed by spontaneous breakup of a deposited thin gold film. The results successfully highlight the ability of SERS to unveil time-resolved MEH-PPV doping and polaron formation, elucidating the effects of triflate ion transfer in the operating device and validating the electrochemical doping model in LECs.

The two-electron oxygen reduction reaction (ORR), powered by affordable renewable energy, presents a more promising and sustainable approach to hydrogen peroxide production than traditional methods. In this study, we introduce a membrane electrolyzer for ORR-to-H2O2 generation. The conducting polymer poly(3,4-ethylenedioxythiophene):poly(styrene sulfonate) (PEDOT:PSS) acts as the cathode that aids the oxygen reduction reaction through a two-electron pathway to produce H2O2. At the anode, we employed the oxidation of a model organic molecule, 4,5-dihydroxy-1,3-benzenedisulfonic acid disodium salt monohydrate (tiron). This catalyst-free anode process, as an alternative to the sluggish water oxidation reaction commonly used in classical electrolyzers, reduces voltage loss to release protons, cross the membrane, and feed the ORR at the cathode. Our study investigated the often-neglected issue of organic crossover during electrolyzer operation and its significant impact on transport behavior. This research paves the way for the development of crossover-free flow cells, extending the realm of electrochemical devices based on the electrolyte fed and the membrane. We introduce a membrane electrolyzer for the generation of hydrogen peroxide via oxygen reduction and catalyst-free oxidation of quinones. The study reports the effect of the applied coulombic forces on ions, which is the origin of crossover.

Silk fibers have unique mechanical properties, and many studies of silk aim at understanding how these properties are related to secondary structure content, which often is determined by infrared spectroscopy. We report significant method-induced irreversible structural changes to both natural and synthetic spider silk fibers, derived from the widely used attenuated total reflection Fourier-transform infrared (ATR-FTIR) technique. By varying the force used to bring fibers into contact with the internal reflection elements of ATR-FTIR accessories, we observed correlated and largely irreversible changes in the secondary structure, with shape relaxation under pressure occurring within minutes. Fitting of spectral components shows that these changes agree with transformations from the alpha-helix to the beta-sheet secondary structure with possible contributions from other secondary structure elements. We further confirm the findings with IR microspectroscopy, where similar differences were seen between the pressed and unaffected regions of spider silk fibers. Our findings show that ATR-FTIR spectroscopy requires care in its use and in the interpretation of the results.

Electrocatalysis for energy‐efficient chemical transformations is a central concept behind sustainable technologies. Numerous efforts focus on synthesizing hydrogen peroxide, a major industrial chemical and potential fuel, using simple and green methods. Electrochemical synthesis of peroxide is a promising route. Herein it is demonstrated that the conducting polymer poly(3,4‐ethylenedioxythiophene), PEDOT, is an efficient and selective heterogeneous catalyst for the direct reduction of oxygen to hydrogen peroxide. While many metallic catalysts are known to generate peroxide, they subsequently catalyze decomposition of peroxide to water. PEDOT electrodes can support continuous generation of high concentrations of peroxide with Faraday efficiency remaining close to 100%. The mechanisms of PEDOT‐catalyzed reduction of O2 to H2O2 using in situ spectroscopic techniques and theoretical calculations, which both corroborate the existence of a chemisorbed reactive intermediate on the polymer chains that kinetically favors the selective reduction reaction to H2O2, are explored. These results offer a viable method for peroxide electrosynthesis and open new possibilities for intrinsic catalytic properties of conducting polymers.

Cornea diseases are a leading cause of blindness and the disease burden is exacerbated by the increasing shortage around the world for cadaveric donor corneas. Despite the advances in the field of regenerative medicine, successful transplantation of laboratory‐made artificial corneas is not fully realized in clinical practice. The causes of failure of such artificial corneal implants are multifactorial and include latent infections from viruses and other microbes, enzyme overexpression, implant degradation, extrusion or delayed epithelial regeneration. Therefore, there is an urgent unmet need for developing customized corneal implants to suit the host environment and counter the effects of inflammation or infection, which are able to track early signs of implant failure in situ. This work reports a nanotoolbox comprising tools for protection from infection, promotion of regeneration, and noninvasive monitoring of the in situ corneal environment. These nanosystems can be incorporated within pro‐regenerative biosynthetic implants, transforming them into theranostic devices, which are able to respond to biological changes following implantation.

Epitaxial graphene (EG) on silicon carbide (SiC) is a combination of two robust materials that are excellent candidates for post silicon electronics. In this work, we systematically investigate structural changes in SiC substrate as well as graphene on SiC and explore the potential for controlled applications due to 100 MeV silver swift heavy ion (SHI) irradiation. Raman spectroscopy showed fluence dependent decrease in intensity of first and second order modes of SiC, along with decrease in Relative Raman Intensity upon ion irradiation. Similarly, Fourier-transform infrared (FTIR) showed fluence dependent decrease in Si-C bond intensity with presence of C = O, Si-O-Si, Si-Si and C-H bond showing introduction of vacancy, substitutional and sp(3) defects in both graphene and SiC. C1s spectra in XPS shows decrease in C = C graphitic peak and increase in interfacial layer following ion irradiation. Reduction in monolayer coverage of graphene after ion irradiation was observed by Scanning electron microscopy (SEM). Further, UV-Visible spectroscopy showed increase in absorbance of EG on SiC at increasing fluence. I-V characterization showed fluence dependent increase in resistance from 62.9 O in pristine sample to 480.1 Omega in sample irradiated at 6.6 x 10(12) ions/cm(2) fluence. The current study demonstrates how SHI irradiation can be used to tailor optoelectronic applicability of EG on SiC.

The rapid technological developments enforce us to live in an increasingly electronic world, and the revolutionary usage of conjugated polymers in electronics in the late 1970s accelerated these developments, based on the unique characteristics of conjugated polymers, such as low cost, easy processing, mechanical flexibility, large-area application and compatibility with a variety of substrates. Organic electronic devices are commercially available in the form of, for example, solar cells, transistors, and organic light-emitting diode (OLED) displays. Scientists work on electroactive polymers to enhance their chemical, electrical and mechanical properties, to improve parameters such as charge carrier mobility and doping capacity, in order to reach acceptable efficiency and stability to fabricate organic electronic devices. A comprehensive understanding of the changes in chemical structure, in response to external factors such as applied potential and temperature gradients, which can disturb the chemical equilibrium of the constituent materials, and of the conduction mechanisms of the operating devices, can help to enhance the performance of organic electronics devices. Vibrational spectroscopy is a powerful analytical method for in-situ monitoring of such chemical or electrochemical reactions and associated structural changes of conjugated polymers in a working device.

In this thesis, Fourier-transform infrared (FTIR) spectroscopy has been used to study the structural changes in electroactive organic materials, in response to chemical or electrochemical reactions, and to study electrical and thermal conduction mechanisms in different organic electronic devices. FTIR microscopy was used to approach a realistic conduction mechanism by time-resolved chemical imaging of active materials in planar light-emitting electrochemical cells (LECs), investigated as an alternative to organic light emitting diodes (OLEDs). These chemical images are used for in-situ mapping of anion density profiles, polymer doping, and dynamic junction formation in the active layer under an applied bias. Results confirm the electrochemical doping model and help the systematic improvement of function and manufacture of LECs. Mixed ion-electron polymeric conductor materials such as PEDOT-PSS are used as active materials in organic thermoelectric generators (OTEGs), where charge carrier transport through the active layer promotes internal electrochemical reactions under a temperature gradient. FTIR microscopy and FTIR-attenuated total reflection (FTIR-ATR) were used to study thermoelectric and electrical properties of the conducting polymers. Recently, electrochemical supercapacitors have emerged as an alternative to conventional batteries, and polymeric materials are used to design polymer electrodes for renewable energy storage. To understand the charge transfer and structural changes of the polymer during the redox reaction, we have used FTIR-ATR as a tool for the in-situ spectroelectrochemical study of redox states in polypyrrole/lignin composites; we clarified the structural changes in the materials during charging and discharging of the composite. In further work, FTIR-ATR was also used for in-situ spectroelectrochemical studies of PEDOT:Cl, to monitor the effects of dissolved oxygen on PEDOT:Cl films, which are used as electrodes in renewable energy technologies. Further, time-resolved oxygen reduction reactions of PEDOT:Cl have been studied via polarization-modulation infrared reflection-absorption spectroscopy (PM-IRAS) to reveal chemical changes in electrochemically doped PEDOT upon exposure to oxygen.

Taken together, these studies provide an advancement in the use of infrared spectroscopy as a tool to understand electroactive materials under wet conditions, and have provided detailed chemical and electrochemical information of materials and devices under operation, that is not easily accessible with other methods.

A light-switchable graphene interface to control and regulate electrobiocatalysis in a nanoconfined space is reported for the first time. The development of switchable and/or tunable interfaces on 2D nanosurfaces endowed with desirable functionalities, and incorporation of these interfaces into remote controlled biodevices, is a rapidly emerging area in bioelectronics.

PEDOT-Tos is one of the conducting polymers that displays the most promising thermoelectric properties. Until now, it has been utterly difficult to control all the synthesis parameters and the morphology governing the thermoelectric properties. To improve our understanding of this material, we study the variation in the thermoelectric properties by a simple acido-basic treatment. The emphasis of this study is to elucidate the chemical changes induced by acid (HCl) or base (NaOH) treatment in PEDOT-Tos thin films using various spectroscopic and structural techniques. We could identify changes in the nanoscale morphology due to anion exchange between tosylate and Cl- or OH-. But, we identified that changing the pH leads to a tuning of the oxidation level of the polymer, which can explain the changes in thermoelectric properties. Hence, a simple acid-base treatment allows finding the optimum for the power factor in PEDOT-Tos thin films.