Due to the high demand of proteins in the pharmaceutical and biotechnological fields, the number of available proteins obtained through DNA recombinant techniques has significantly increased. The high demand for protein production has motivated a need for more efficient and sustainable methods for protein purification in downstream processing. Currently, chromatography is the primary method used in protein purification. However, it is generally regarded to be expensive and cannot be easily applied to large amounts of protein raw materials.
Preparative protein crystallization is regarded as a promising alternative for protein purification as it does not suffer the limitations of chromatography. However, protein crystallization is a complex, not well understood process. Hence, its implementation requires extensive crystallization screening with moderate success. In this poster, a new strategy for enhancing protein crystallization from metastable protein-rich droplets generated by liquid-liquid phase separation (LLPS) is outlined. This strategy requires the use of two additives. One additive promotes LLPS (inducer), and the other additive (modulator) alters the composition of droplets and their thermodynamic stability. This strategy is supported by our recent work on lysozyme in the presence of NaCl (inducer) and 4-(2-hydroxyethyl)-1-piperazineethanesulfonate (HEPES, modulator).

Artificial photosynthesis utilizes controlled photochemical reactions to store light energy from the sun as chemical potential energy (that of new chemical bonds). This study describes the fabrication and study of nanostructured BiVO4 photoanodes to optimize the capture and conversion of light energy to chemical potential energy. BiVO4 is a promising n-type semiconductor due to its ability to absorb a portion of the visible light spectrum. Moreover, BiVO4 is an eco-friendly material which exhibits an optimal conduction and valence band edge position to perform water oxidation. Research has suggested that the oxidative performance of bismuth vanadate films is based on both the overall surface area and presence of grain boundaries which can alter the chemical conductivity of the photoanode interface. Specifically, this work aims to alter the porosity and structure of the BiVO4 film by controlling the concentration of polymer additive, polyethylene glycol (PEG), used as a templating agent in the precursor sol-gel. Changing the PEG concentration should affect both the surface porosity and film thickness. The application of the film involves a simple liquid-phase, dip-coating deposition which is easily reproducible. We hypothesize that an increase in surface area and porosity of the photoanode interface will result in an increase in overall photocurrent generation. These nanostructured photoanodes were used to measure the oxidation of the stable radical, (2,2,6,6-tetramethylpiperidin-1-yl)oxyl (TEMPO), via photoelectrochemical analysis. Our findings provide insight into a simple yet effective fabrication procedure of photoanodes for use in renewable solar chemical applications.

Oxidative stress refers to the imbalance between free radical activity and antioxidant activity in the body, and is known to play a crucial role in diseases such as age-related macular degeneration in eyes and various neurodegenerative diseases (Alzheimer’s and Parkinson’s). To help the body target and rebalance this process, the Green group at TCU has developed pyridinophane macrocycle frameworks (PyN3, Py2N2) for the development of a small multimodal molecule with direct targeting of oxidative stress through various approaches (metal binding, N-oxide formation, radical scavenging, and Nrf2 pathway activation). The group proposed a library of ligands as modifications to the pyridinophane frameworks to enhance antioxidant activity, which resulted in 18,000 possible molecule structures. Computational pre-screening will be essential to select the most promising candidates for synthesis and experimental tests. We wrote a program in Python using the open-source RDKit toolkit to generate a library of 13,000 prospective reduced-dimension pyridinophane macrocycle derivatives from SMILES strings based on the variation of ligands and attaching position to the frameworks, screen these compounds for their basic chemical and pharmacological properties, and identify those that fit the required biocompatibility, metabolic stability, and permeability for medicinal drug development. The properties to be computed through the virtual screening are molecular weight (MW), solubility, ring count, Lipinski’s parameters for orally active drugs, which includes octanol-water partition coefficient cLogP, number of hydrogen bond donors (HBD) and acceptors (HBA), and polar surface area (PSA). This program, therefore, helps save time and resources for synthesis while offering better optimization of chemical frameworks, and thus it can be applied to the development of various types of medicinal drugs.

In recent years, macrocycles have emerged to be potential drug leads, as they show to have promise for targeting disease pathways, however their synthesis is quite difficult and has yet to be optimized. Utilizing glycine specifically in macrocycle synthesis was the objective, and this was done by stepwise reactions of successfully adding compounds onto glycine to prepare for cyclization. Cyanuric chloride, BOC-hydrazine, and morpholine were successfully added to glycine, as proven with thin layer chromatography and NMR. However, problems that arose came with purifying the compound for cyclization due to solubility issues. Many attempts utilized column chromatography, but there seems to be promise in utilizing an extraction to purify the compound and prepare for cyclization.

Micellization is a phenomenon of central importance in surfactant solutions. Here, we demonstrate that the diffusion-based spreading of the free boundary between a micellar aqueous solution and pure water yields a one-dimensional spatial profile of surfactant concentration that can be used to identify the critical micelle concentration, here denoted as C*. This can be achieved because dilution of micelles into water leads to their dissociation at a well-defined position along the concentration profile and an abrupt increase in diffusion coefficient. Rayleigh interferometry was successfully employed to determine C* values for three well-known surfactants in water at 25 ºC: Triton X-100 (TX-100), Sodium Dodecyl Sulfate (SDS), and Polyoxyethylene(4)Lauryl Ether (Brij-30). The dependence of C* on salt concentration was also characterized for TX-100 in the presence of Na2SO4, NaCl, and NaSCN. Accurate values of C* can be directly identified by visual inspection of the corresponding concentration-gradient profiles. To apply the method of least squares to experimental concentration profiles, a mathematical expression was derived from Fick’s law and the pseudo-phase separation model of micellization with the inclusion of appropriate modifications. While Rayleigh interferometry was employed in our experiments, this approach can be extended to any experimental technique that yields one-dimensional profiles of surfactant concentration. Moreover, diffusion-driven surfactant disaggregation is precise, non-invasive, requires single-sample preparation, and applies to both non-ionic and ionic surfactants. Thus, this work provides the foundation of diffusion-driven dilution methods, thereby representing a valuable addition to existing techniques for the determination of C*.

Organic dyes with photophysical properties affected by alterations in the properties of the media, including viscosity, temperature, and polarity, are known as environment-sensitive probes. These probes are widely used in various areas of analytical, biological and material sciences. This poster will describe our initial efforts on designing multi-responsive environment-sensitive probes based on squaric acid scaffolds. Specifically, the incorporation of aminoquinoline moieties produced small molecule viscometers, which have the ability to sense polarity variations of organic solvents. Multiplexing abilities, coupled with modular and facile synthesis, distinguishes these probes from other types.

Oxidative stress is a result of an imbalance between reactive oxygen species (ROS) and the availability/activity of antioxidants. The catalase family of enzymes mitigate the risk from ROS by facilitating the disproportionation of hydrogen peroxide into molecular oxygen and water. Manganese containing catalase (MnCAT) consists of a binuclear manganese core bridged by carboxylate and single-atom ligands, likely water or hydroxide. In this work, hydrogen peroxide disproportionation using complexes of manganese with cyclen and pyclen were investigated due to the spectroscopic similarities of the latter with the native MnCAT enzyme. Potentiometric titrations were used to construct speciation curves to identify what complex compositions were present at different pH values. Based on these results, the complexes were made in situ by mixing stock solutions of ligand, buffer, and metal. The hydrogen peroxide disproportionation reaction was carried out in a sealed cell and PO2 measured using a microsensor (Unisense). When hydrogen peroxide was injected into the cell, disproportionation activity of the complexes was evident by (1) appearance of bubbles in solution, and (2) noticeable increase in PO2 as measured by the sensor. Spectroscopic investigation before, during, and after the reaction was used to follow changes in the UV-visible absorption of the complexes to collect information about the structure of the initial catalyst and any possible intermediate. Both, pyclen and cyclen were determined to form a dimeric structure under the reaction conditions used.

Many drugs today are small molecules and function through a specific binding with their target. This has proved to be efficient, yet the idea of larger macromolecules being used as drugs has grown more popular because of their flexibility. The issue with these larger molecules is that they have been previously difficult to synthesize. The emphasis of the research is to find an efficient way to synthesize macrocycles, reducing purification processes and side products. All reactions are done in solution and column chromatography is used to purify. An important aspect is testing if this cyclization method is possible with all amino acids or if limitations are present based on the backbone of the molecule. Because macrocycles have proved difficult to synthesize in the past, they are overlooked in the field of drug design. However, with this rather basic process it is possible to create new rules associated with drug design and defy what was once believed about macrocycles.

The aptamer domain of a naturally occurring glycine riboswitches was randomized to generate a library containing billions of different variants. The dual genetic selection of this library was performed for sarcosine, a prostate cancer marker, and successfully led to the identification of sarcosine-specific synthetic riboswitches. When a chloramphenicol-resistance gene was expressed under control of these riboswitches, E. coli cells showed chloramphenicol resistance only in the presence of sarcosine. For a colorimetric assay, the sarcosine riboswitch gene was inserted upstream of the lacZ gene. When tested with various concentrations of sarcosine, the enzymatic activity of LacZ was proportional to the amount of sarcosine, clearly indicating the sarcosine-dependent gene regulation by the sarcosine riboswitch.

Triazines appear in pharmaceuticals, agrochemicals, and as building blocks for polymers used in materials science and medicine. Predicting the structure and dynamics in water as a function of pH requires reliable simulations of the pKa values for different sites for protonation. We present the initial DFT methods and continuum solvent for pKa of amines, ring nitrogens, and 2,4,6-triamino-1,3,5-triazine (melamine) derivatives. These M06-2X/6-311++G(2d,2p) calculations in SMD continuum solvent provide consistent accuracy for tested systems, use for future studies of more complex structures.

Organic synthesis and research into the activity and uses for macrocycle compounds have increased in recent years. These compounds proved to be an interesting field of research due to their size and ability to orient in different ways depending on the environment. The synthesis of these molecules is done by using a stable foundation molecule, cyanuric chloride, which is subject to substitution. The compound can be built from there using nucleophilic substitution with various nitrogen-based compounds. Then, in the final steps of the synthesis, the compounds dimerize forming the macrocycle. The amino acid nucleophile used to build the molecule is being varied to build many different compounds. The challenge, however, is to find the most efficient route for synthesis. I have successfully managed to synthesize one macrocycle compound using lysine with a Z protecting group as the starting material. Throughout the synthesis there was great difficulty with the compound’s solubility, therefore the starting material was switched to a BOC protected lysine amino acid. This resulted in better solubility throughout the process and yielded another successful macrocycle. These results demonstrate how the synthesis pathway we used to build these macrocyclic dimers is successful, but the process can be variable, based on the properties of the amino acid. It is recognized how the synthesis of these compounds is only the first step and further research into the properties and actions of the compounds is necessary. However, a pure product and efficient synthesis in making the macrocycle is important to properly access its properties. My further research will specifically test the antibiotic properties, if any, the macrocycles possess.

The mis-regulation of reactive oxygen species (ROS) and transition metals contribute to the onset of Alzheimer’s Disease (AD). A tetra-aza macrocyclic pyridinophane with an indole moiety, (Ind)PyN3, was evaluated on its radical scavenging reactivity and ability to chelate and stabilize the copper (II) oxidation state; these evaluations contribute to the overall therapeutic efficacy of the ligand in treating AD. Compared to a congener replacing the indole moiety with a hydroxyl moiety, (OH)PyN3, (Ind)PyN3 displayed comparable radical scavenging reactivity to (OH)PyN3. The fluorometric CCA assay revealed that (Ind)PyN3 was able to the stabilize the copper (II) oxidation state and prevent it from generating ROS via redox cycling at both 1 and ½ equivalents, albeit (OH)PyN3 was more effective at copper (II) oxidation state stabilization than (Ind)PyN3 at half molar equivalence. Our results demonstrate that the addition of the indole moiety to a tetra-aza macrocyclic pyridinophane does not disrupt radical scavenging reactivity by the indole moiety nor the ability of the pyridinophane to stabilize transition metal ions, warranting future exploration of the indole moiety in therapeutic design for AD.

Owing to the increasing importance of manganese(II) complexes in the field of magnetic resonance imaging (MRI), large efforts have been devoted to find an appropriate ligand for Mn(II) ion encapsulation by providing balance between the seemingly contradictory requirements (i.e., thermodynamic stability and kinetic inertness vs low ligand denticity enabling water molecule(s) to be coordinated in its metal center). Among these ligands, a large number of pyridine or pyridol based open-chain and macrocyclic chelators have been investigated so far. As a next step in the development of these chelators, 15-pyN3O2Ph and its transition metal complexes were synthesized and characterized using established methods. The 15-pyN3O2Ph ligand incorporates both pyridine and ortho-phenylene units to decrease ligand flexibility. The thermodynamic properties, protonation and stability constants, were determined using pH-potentiometry; the solid-state structures of two protonation states of the free ligand and its manganese complex were obtained by single crystal X-ray diffractometry. The results show a seven-coordinate metal center with two water molecules in the first coordination sphere. The longitudinal relaxivity of [Mn(15-pyN3O2Ph)]2+ was found to be 5.16 mM−1 s−1 at 0.49 T (298 K). Furthermore, the r2p value of 11.72 mM−1 s−1 (0.49 T), which is doubled at 1.41 T field, suggests that design of this Mn(II) complex does achieve some characteristics required for contrast imaging. In addition, 17O NMR measurements were performed in order to access the microscopic parameters governing this key feature (e.g., water exchange rate). Finally, manganese complexes of ligands with analogous polyaza macrocyclic scaffold have been investigated as low molecular weight Mn(CAT) mimics. Here, we report the H2O2 disproportionation study of [Mn(15-pyN3O2Ph)]2+ to demonstrate the versatility of this platform as well.

Dispersion interactions also known as van der Waals interactions are essential for everything from nanomaterials to organic chemistry to biological chemistry. Modeling that chemistry requires modeling van der Waals interactions. Approximations that start from “freshman chemistry” molecular orbital (MO) theory do not account for dispersion. For example, helium-helium interactions are unbound in molecular orbital theory as two electrons are placed in antibonding orbital, but in reality, the interactions are weakly bound and can form a liquid. We have developed a density functional theory method embodying MO theory and corrections. Dispersion corrections can be added to noncovalent interactions in order to model them by using a standard model with different parameters. By fitting these parameters, the accurate known bond energies of real noncovalent complexes can be reproduced.

This project is aimed to develop triazine-based fluorescent bivalent antibody mimics against the epidermal growth factor receptor (EGFR), a protein disease marker for cancer. A synthetic gene for the anti-EGFR Z-domain was constructed by overlapping extension PCR and inserted into the pET-Z plasmid to produce pET-Z anti-EGFR. The anti-EGFR Z-domain variant was expressed as a C-terminal His-tag fusion in BL21(DE3) E. coli cells transformed with the pET-Z anti-EGFR plasmid and purified by immobilized metal ion affinity chromatography. A dansyl fluorophore was attached to the first position of a triazine core that has three positions available for modification. To the second available position of the dansyl-triazine conjugate, an anti-EGFR Z-domain molecule was selectively attached to generate a monomeric conjugate. Another anti-EGFR Z-domain molecule will be attached to the remaining position of the triazine core to produce a dimeric conjugate. We will test the fluorescent monomeric and dimeric anti-EGFR Z-domain conjugates for binding to the EGFR by a standard ELISA method and isothermal titration calorimetry.

Fmoc-protected and propargyl-containing thymine and Cbz-protected cytosine monomers were synthesized for possible use in the pre- or post-functionalization of PNA oligomers via click chemistry. The monomers should be suitable for incorporation in normal automated solid phase PNA synthesis. The synthesis is suitable for the preparation of gram-quantities of monomers and uses reductive amination as the key step.

Alzheimer's disease is a neurodegenerative disorder that is characterized by amyloid-beta plaques, neurofibrillary tangles, and unregulated reactive oxygen species. The production of reactive oxygen species in the brain is exacerbated by an excess of free-metal ions in nervous tissue. Our team and others have shown a library of tetra-azamacrocycles to have the ability to scavenge free-metal ions and quench reactive oxygen species. These macrocyclic ligands have, thus, been considered as potential therapeutic agents for combatting Alzheimer’s disease. The ability of a neuro-active pharmaceutical to cross the blood-brain barrier is crucial to its pharmacological success and has proven to be a significant challenge to date in moving molecules from the bench to clinical treatment paradigms. The aim of this work is to enhance the pharmacological potential of these macrocyclic ligands. To accomplish this, computational analyses were performed on two tetra-azamacrocycles to predict their baseline blood-brain barrier permeability. The structures of these macrocycles were then modified with various moieties and analyzed via the same computational methods to predict their blood-brain barrier permeability potential. One target modification this project is focused on is the attachment of omega-3 fatty acids to these tetra-azamacrocycles. Omega-3 fatty acids have been shown to have beneficial anti-inflammatory properties in vivo and have the ability to assist in transporting molecules across the blood-brain barrier. Thus, the inclusion of these moieties to the structure of the Green Group ligands are attractive in regard to enhancing their pharmacological potential. To accomplish this attachment, the synthetic approach of one of the Green Group’s flagship tetra-azamacrocycles, OHPy-N3, had to be completely reimagined. New synthetic approaches and protection strategies were employed to achieve a suitable intermediate molecule primed for the addition omega-3 fatty acids. These novel synthetic methods and subsequent results are discussed in this work herein.

The objective of this project is to make a vaccine that will negate the effects of the powerful opioid fentanyl in the long term. Fentanyl is a strong synthetic opioid that is 50 to 100 times more potent than morphine. According to the CDC, there were over 70,000 deaths due to street drug overdoses, which has increased in the last ten years. 40 % of these deaths are related to fentanyl overdoses, therefore it is imperative that approaches are developed to combat this alarming increase in deaths. The vaccine against fentanyl will be synthesized out of molecules that will take advantage of fentanyl’s amide functional group to be hydrolyzed into safe byproducts. Any patient that is administered with the vaccine, will not feel the effects of the opioid because the immune system will hydrolyze the drug as soon as it enters. This project will exploit the properties of both catalytic antibodies (CAbs) and transition state analogs. If the molecule resembles the transition-state of fentanyl hydrolysis, then the antibodies can cleave the fentanyl in a fast and efficient manner due to their catalytic properties. Therefore, after immunization, a person who is addicted to fentanyl would no longer feel the effects of the opioid because it will be degraded as soon as an immune response is triggered, creating a long-term possible solution to one factor of the “opioid crisis.”

Alkenyl phosphorus compounds appear in multiple industrial products, from flame retardants to fungicides. Although several methods are available to synthesize these compounds, many require expensive catalysts, inaccessible starting materials, or multi-steps sequences. In response to these issues, this project sought to develop an efficient, two-step method to synthesize alkenyl phosphorus compounds from simple ketones. We compare acid and base catalysts and find both are effective in the first reaction step; furthermore, a one-pot reaction provides comparable yields to the reactions conducted with a purified intermediate. These findings lay the foundation for the exploration of more complex substrates, including those utilized in industrial applications.

Pyridine macrocycles have useful applications due to their ability to complex with metals. A library of substituted pyridine macrocycles exists along with how modifications at Carbon 4 impact compound reactivity. Despite literature about similar pyridine macrocycle structures, little is known about how an iodo-substituted pyridine macrocycle will alter the properties of the compound when complexed to Copper. To understand the fundamental characteristics of an Iodo-substituted pyridine macrocycle, the ligand is synthesized followed by electronic environment analysis via 1H NMR. Ultraviolet-Visible Spectroscopy is used to verify ligand complexation with Copper (II) metal followed by X-ray diffraction to determine metal binding nature of the complex. Cyclic Voltammetry analysis is used to support the theory that the iodo functional group behaves as an electron withdrawing group. This compound serves as a comparison to explain the results of the Chloro-substituted pyridine macrocycle as well as a gateway molecule for the synthesis of new pyridine macrocycles.

Porous silicon nanoparticles exhibit great potential as drug delivery vectors due to their high surface-area-to-volume ratio allowing for increased efficacy of surface functionalization and therapeutic loading capabilities. This data set demonstrates the fabrication of a class of plant-derived materials which are sub-micron in size and capable of functionalization with primary amine groups through the addition of APTES.
The production of porous silicon particles (pSi) is achieved through magnesiothermic reduction of silica containing Tabasheer powder isolated from the nodal joints of the Bambuseae plant. Efficacy of this reduction is evaluated using techniques including X-ray diffraction and Energy-dispersive X-ray spectroscopy which show successful reduction of silica starting material to porous silicon.
High energy ball milling followed by reduction is used to produce pSi particles of sub-micrometer size while also allowing for a significantly higher yield (~90%) of material than previous methods. Particle size is confirmed via electron microscopy and dynamic light scattering (DLS).
Following reduction, surface functionalization of silicon nanoparticles with primary amine groups was carried out using a 4% (v/v) solution of APTES in acetone. The evaluation of this functionalization was conducted using techniques including zeta potential and infrared spectroscopy (IR). Zeta potential values are found to be approximately -10 mV. This data demonstrates successful amino silanization.
The results achieved through these methods suggest successful fabrication of pSi nanoparticles and subsequent functionalization for future use as a drug delivery vector.

Drug delivery is the process by which medications are administered to the body. This is complex due to the difficulty of determining compounds that have the proper biocompatibility and permissibility to our human cells. Many medications are taken orally; however, there are advantages to administering medication subcutaneously or by inserting it in the inner corner of the eye. Porous films made out of biocompatible polymers provide a good platform for drug delivery as they have the ability to be loaded with plant derived porous Silicon. Functionalizing the porous silicon using (3-aminopropyl)triethoxysilane and glutaraldehyde can be done in an attempt to covalently attach particles to the film which is important for embedding them into the pores of the film. Porous silicon has biocompatible properties and can be loaded with drugs then modified to alter the release of those drugs in the body. This method has the potential to be a useful drug delivery method due to the biocompatible and biodegradable properties of the material and the ability to manipulate the material in order to maximize drug release.

In cancer therapy, nucleic acid-based therapeutic strategies have been extensively investigated to suppress mutated gene expression, thereby inhibiting cancer cell growth. Among the approaches, small interfering (siRNA)-mediated gene silencing has been envisaged as a promising therapeutic approach to silence specific gene expression by targeting mRNA of the unwanted gene for degradation, thereby readily controlling cellular functions. However, delivery of small interfering RNA (siRNA) has been known to encounter multiple challenging barriers, such as blood circulation and cellular internalization, thus limiting the potential merits of this therapeutic strategy. While non-viral vectors have been preferred owing in part to better immune system compatibilities, porous silicon (pSi) with various geometric shapes (e.g. platelet and discoid) have recently been demonstrated as exceptional delivery carriers of siRNA in various disease models. Here our initial in vitro studies show that silicon in a unique one-dimensional porous nanotube structure (pSiNTs) can serve as a promising vector for delivery of siRNA to limit target gene expression, thereby expanding the library of possible nanostructures of Si in delivery of siRNA.
In this work, we demonstrate that pSiNTs after being functionalized with 3-(aminopropyl)triethoxysilane (APTES) can deliver enhanced green fluorescence protein (EGFP)-targeting-siRNA via electrostatic conjugation and suppress EGFP expression in HeLa cervical cancer cells by up to 50%. Cytocompatibility and biodegradation of the functionalized pSiNT matrix upon siRNA delivery are characterized by ATP quantification assays (CellTiter Glo) and Transmission Electron Microscopy imaging (TEM) respectively. These results encourage further development of pSiNTs in therapeutic applications.

The objective of this project is to make a vaccine that will negate the effects of the powerful opioid fentanyl in the long term. Fentanyl is a strong synthetic opioid that is 50 to 100 times more potent than morphine. According to the CDC, there were over 70,000 deaths due to street drug overdoses, which has increased in the last ten years. 40 % of these deaths are related to fentanyl overdoses, therefore it is imperative that approaches are developed to combat this alarming increase in deaths. The vaccine against fentanyl will be synthesized out of molecules that will take advantage of fentanyl’s amide functional group to be hydrolyzed into safe byproducts. Any patient that is administered with the vaccine, will not feel the effects of the opioid because the immune system will hydrolyze the drug as soon as it enters. This project will exploit the properties of both catalytic antibodies (CAbs) and transition state analogs. The Cabs will trigger an immune response to attract phagocytic cells, such as macrophages to phagocytose pathogens and eliminate them from the system. However, if the molecule resembles the transition-state of fentanyl hydrolysis, then the antibodies can cleave the fentanyl in a fast and efficient manner due to their catalytic properties. Therefore, after immunization, a person who is addicted to fentanyl would no longer feel the effects of the opioid because it will be degraded as an immune response is triggered, creating a long-term possible solution to one factor of the “opioid crisis.”

It is extremely important in our age to look for alternative, more environmentally favorable energy sources. The Sun is a largely unused and widely available energy source to power human industry which can be utilized in different ways. Photovoltaic cells directly convert solar energy to electricity but only provide power when illuminated. Supplying solar-sourced energy during night hours and inclement weather requires conversion to another form, for instance into chemical fuel by means of water splitting into oxygen and hydrogen. This strategy, inspired by natural photosynthesis, is currently a promising and actively researched approach. However, achieving a high energy conversion efficiency, which is essential for industrial implantation of the method, remains a primary goal.
A Dye-Sensitized Photoelectrochemical Solar Cell (DSPEC) is specifically designed for using solar energy to generate hydrogen from water. We are pursuing the formation of photoanodes with polymer surface coatings prepared by electropolymerization. The polymer interfaces are designed to promote directional electron transfer at the interface, thereby resulting in a better solar energy conversion efficiency. The structure of the surface polymer enables the incorporation of catalyst units to the interface. To this end, we have prepared several novel iridium-oxide nanoparticle suspensions, using two different synthetic methods, to serve as the water-oxidation catalysts in our system. During the synthesis, the nanoparticles are functionalized with specific capping groups that contain terminal double bonds, through which they can be incorporated to the surface polymer electrochemically. Using acrylic acid and acrylamide as small molecule precursors, electro-polymer coatings have been prepared on FTO (fluorine-doped tin oxide) surfaces. Future research work will involve the incorporation of functionalized iridium oxide nanoparticles in the poly(acrylic acid/acrylamide) films and the characterization of their catalytic activity toward water oxidation. The method will then be extended to tin-oxide and titanium-dioxide semiconductor electrodes for preparing photo-active interfaces.