​Abstract:  Optical sensors based on Surface-enhanced Raman scattering (SERS) effect are among the most versatile sensors due to their ability to characterize samples in various state of matter. The appeal of the SERS sensors lies in the molecular “fingerprint” specificity, sensitivity, and the non-invasive nature of the analysis. Although the current state of art SERS sensors have advanced toward ultrasensitivity with single-molecule detection limit, ultrafast analysis at femtosecond and sub-nanometer resolution, the application of these innovations in the industrial settings is still limited by the complexity of the substrate fabrication and the reproducibility of the SERS measurements. In this context, a study on the SERS sensors fabrication strategies and reliability of the SERS analysis is essential. This dissertation investigates various hybrids of noble metal and semiconductor materials and surface modifications to improve the stability and reliability of SERS measurement. Different industrial applications, including detection of petrochemical organic compounds and sensitive biochemical samples, were conducted to evaluate the performance of different SERS sensor designs. Evaluation of the morphology and surface functionalization of the substrate was accomplished to optimize the performance and stability of the collected signal. Together with the separately performed studies on Raman signal processing and interpretation, the proposed SERS sensor fabrication and signal analysis approach was successfully applied to detect and quantify organic isomers compounds and mutation point in peptides. The findings presented in this thesis offer rational SERS substrate designs and detection approaches which can advance the future commercialization of SERS sensors.

MORE INFORMATION

• CONTACTLinda J. Sapolu
• EMAILLinda.Sapolu@kaust.edu.sa

​Abstract:
By controlling the exposed chemical functionality of materials from the submolecular through the centimeter scale, we have enabled new capabilities in biology, medicine, and other areas. I will discuss current and upcoming advances and will pose the challenges that lie ahead in creating, developing, and applying new tools using this capability. These advances include using biomolecular recognition in sensor arrays to probe dynamic chemistry in the brain and microbiome systems. In other areas, we introduce biomolecular payloads into cells for gene editing at high throughput for off-the-shelf solutions targeting hemoglobinopathies, immune diseases, and cancers. We circumvent the need for viral transfection and electroporation, both of which have significant disadvantages in safety, throughput, cell viability, and cost. Mechanical deformation can make cell membranes transiently porous and enable gene-editing payloads to enter cells. These methods use specific chemical functionalization and control of surface contact and adhesion in microfluidic channels. 

Biography:
Paul S. Weiss holds a UC Presidential Chair and is a distinguished professor of chemistry & biochemistry and of materials science & engineering at UCLA. He received his S.B. and S.M. degrees in chemistry from MIT in 1980 and his Ph.D. in chemistry from the University of California at Berkeley in 1986. He was a postdoctoral member of technical staff at Bell Laboratories from 1986-88 and a visiting scientist at IBM Almaden Research Center from 1988-89. He served as the director of the California NanoSystems Institute and held the Fred Kavli Chair in NanoSystems Sciences at UCLA from 2009-14. Before coming to UCLA, he was a distinguished professor of chemistry and physics at the Pennsylvania State University, where he began his academic career in 1989. His interdisciplinary research group includes chemists, physicists, biologists, materials scientists, mathematicians, bioengineers, electrical and mechanical engineers, computer scientists, clinicians, and physician scientists. They focus on the ultimate limits of miniatu­rization, exploring the atomic-scale chemical, physical, optical, mechanical, and electronic properties of surfaces, interfaces, supramolecular, and biomolecular assemblies. They develop new techniques to expand the applicability and chemical specificity of scanning probe microscopies. They apply these and other tools to study self- and directed assembly, and molecular and nanoscale devices. They advance nanofabrication down to ever smaller scales and greater chemical specificity to operate and to test functional molecular assemblies, and to connect to the chemical and biological worlds in neuroscience, gene editing, cancer immunotherapy, and the microbiome. He has written over 400 publications, holds over 30 patents, and has given over 800 invited, plenary, keynote, and named lectures.

Weiss has been awarded a National Science Foundation (NSF) Presidential Young Investigator Award (1991-96), the Scanning Microscopy International Presidential Scholarship (1994), the B. F. Goodrich Collegiate Inventors Award (1994), an Alfred P. Sloan Foundation Fellowship (1995-97), the American Chemical Society (ACS) Nobel Laureate Signature Award for Graduate Education in Chemistry (1996), a John Simon Guggenheim Memorial Foundation Fellowship (1997), a NSF Creativity Award (1997-99), the ACS Award in Colloid and Surface Chemistry (2015), the ACS Southern California Section Tolman Medal (2017), the ACS Patterson-Crane Award in Chemical Information (2018), and the IEEE Nanotechnology Pioneer Award (2019), among others.
He was elected a fellow of:  the American Association for the Advancement of Science (2000), the American Physical Society (2002), the American Vacuum Society (2007), the ACS (2010), the American Academy of Arts and Sciences (2014), the American Institute for Medical and Biological Engineering (2016), the Canadian Academy of Engineering (2017), the Materials Research Society (2019), and an honorary fellow of the Chinese Chemical Society (2010).
He was also elected a senior member of the IEEE (2009). He received Penn State's University Teaching Award from the Schreyer Honors College (2004), was named a nanofabrication fellow at Penn State (2005), and won the Alpha Chi Sigma Outstanding Professor Award (2007).
He was a visiting professor at the University of Washington, Department of Molecular Biotechnology (1996-97) and Kyoto University, Electronic Science and Engineering Department and Venture Business Laboratory (1998 and 2000), and a distinguished visiting professor at the Kavli Nanoscience Institute and the Joint Center for Artificial Photosynthesis at Caltech (2015). He is a visiting scholar at the Kavli Institute for Bionano Science & Technology and the Wyss Institute for Biologically Inspired Engineering at Harvard University (2015-18).
He held the Institut National de la Recherche Scientifique (INRS) Chaire d'excellence Jacques­Beaulieu (2016-17) and was a Fulbright Specialist for the Czech Republic (2017).
Weiss was a member of the U.S. National Committee to the International Union of Pure and Applied Chemistry (2000-05). He has been the technical co-chair of the Foundations of Nanoscience Meetings and thematic chair of the Spring 2009 and Fall 2018 ACS National Meetings.
He was the senior editor of IEEE Electron Device Letters for molecular and organic electronics (2005-07), and is the founding editor-in-chief of ACS Nano (2007-).
At ACS Nano, he won the Association of American Publishers, Professional Scholarly Publishing PROSE Award for 2008, Best New Journal in Science, Technology, and Medicine, and ISI's Rising Star Award a record ten times.

MORE INFORMATION

• CONTACTSijian Hou

Abstract:  This dissertation shed lights on metal-nitrogen organometallic fragments supported on silica surface for catalytic applications. It Focuses on group IV and V metal transition as a well-defined single-site catalysts, specifically titanium, hafnium, and tantalum to utilize them in the development of selective heterogeneous catalysis for imine metathesis, hydroamination and hydroaminoalkylation of olefins and alkynes. Developing new metal-nitrogen containing fragments by using easily available and abundant precursors which is silica (SiO2) and metal amides complexes. Research in this area has led to isolating several intermediates containing nitrogen fragments, this is the strength of surface organometallic chemistry which allows a deeper understanding of catalytic phenomena which could not be approached either in homogeneous catalysis or in classical heterogeneous catalysis. A molecular level characterization of the surface  nitrogen containing fragments have been characterized by SOMC tools such as FTIR and EXAFS spectroscopies, elemental analysis, solid-state single and multiple quantum NMR, and advanced DNP-SENS. A catalytic cycle proposed for each reaction based not only on the isolation of intermediates but also based on DFT calculations

MORE INFORMATION

• CONTACTLinda J. Sapolu
• EMAILLinda.Sapolu@kaust.edu.sa

​Abstract:  Metal–organic frameworks (MOFs) are porous crystalline materials built by metal clusters coordinated to organic ligands. Synthesis of MOFs have attracted great attentions in the last decades owing to its potential for a wide range of applications such as gas separation, dye adsorption, and catalysis etc. The development of MOF membrane further enhances the potential of this material in industrial applications. Membrane fabrication methods including in-situ growth, secondary growth, interfacial growth, dip-coating, and spin coating have been widely studied. However, most of these methods either require complicated operations or are time consuming. Besides these methods, electrochemical synthesis is an emerging method in the recent years to be high potential candidate to make MOF membranes industrial scale-up. This method has advantages of shorter synthesis time, milder synthesis condition, continuous reaction fashion, and crystal self-healing nature. In this work, we used cathodic deposition to fabricate MOF membrane without addition of any supporting electrolyte or modulator in the aqueous medium. The defect-free membranes were synthesized in 60 min without the post-treatment. The membrane showed the best combination of permeance vs. selectivity in the separation of propylene/propane mixture.

MORE INFORMATION

• CONTACTLinda J. Sapolu
• EMAILLinda.Sapolu@kaust.edu.sa

​Abstract:  Metal organic frameworks (MOFs) have showed great promise for membrane based separations, owing to their regular pore structures and precisely controlled pore aperture sizes. Rare earth fcu-MOFs, assembled from rare-earth based hexanuclear clusters and linear ditopic ligands, expressed unique performance in separating different gas pairs and excellent stability in harsh atmospheres, such as H2S. By judiciously selecting different ligands with different length and functionalized groups, we can finely tune the sizes of the triangular windows. Therefore, RE fcu-MOFs can be ideal candidates for tailor-made MOF membranes.

Conventional methods to fabricate supported thin-film MOF membranes, such as solvothermal synthesis, rely on high temperature, high pressure and long growth period. Here we show that RE fcu-MOF membranes can be prepared by a fast current driven synthesis method, where the external current can promote the fast growth of RE fcu-MOF layers on the porous supports at room temperature and ambient conditions. A series of different RE fcu-MOFs with different ligands have been successfully integrated into RE fcu-MOF membranes by current-driven synthesis, which demonstrates the feasibility in combining electrochemistry with reticular chemistry.

MORE INFORMATION

• CONTACTLinda J. Sapolu
• EMAILLinda.Sapolu@kaust.edu.sa

​Abstract:  Room Temperature Ionic Liquids (RTILs) are solvents consisting entirely of ions resembling the ionic melts of metallic salts; however, RTILs are liquids at much lower temperatures.  RTILs have high thermal stability, high ionic conductivity, negligible vapor pressure and are non-flammable.  Unlike traditional organic media, RTIL’s properties may be adjusted via chemical alteration of the cation or anion to produce application specific compounds.  Polymeric versions of ILs have been synthesized and used as membranes for gas separations.  High coulombic forces constrain the RTIL constituents and thus, composite membrane structures can be prepared with a polymer backbone and RTIL added to enhance the gas permeation rate.  Mixed matrix membranes, where a nanoporous solid is added to the composite, have also been prepared.
These composite structures have also been evaluated for electrochemical applications and as barrier materials to protect against chemical warfare agents or toxic industrial chemicals.

Lytotropic Liquid Crystals (LLCs) are amphiphilic molecules containing a hydrophobic organic tail section and a hydrophilic headgroup, which self-assemble in the presence of water or other hydrophilic species into highly ordered, yet fluid phase-separated assemblies with specific nanometer-scale hydrophilic domains. Depending on the shape of the constituent LLCs and the interfacial curvature energy of the system, monodispersed hydrophilic domains ranging in structure from lamellae to cylindrical channels to three-dimensionally interconnected pores with dimensions in the 1–5 nm size range can be formed. By making polymerizable analogs of LLC mesogens, it has been possible to stabilize the various LLC assemblies with retention of phase microstructure via photo-initiated radical cross-linking.  These membranes have charged pores and reject ions in solution analogous to reverse osmosis and small neutral solutes based on size similar to nanofiltration membranes.  These membranes have demonstrated exceptional performance to treat fracking water, reject chemical warfare agents, and operate for electrochemical applications.

Biography:  Education
    Stevens Institute of Technology    Chemical Engineering       B.E. (Honors),           (1968)
    Stevens Institute of Technology        Chemical Engineering       M.E. (Chemical),       (1969)
    University of California, Davis    Chemical Engineering       Ph.D.                          (1976)

MORE INFORMATION

• CONTACTLinda J. Sapolu
• EMAILLinda.Sapolu@kaust.edu.sa