Research Interests
Our research is focused on
the basic and applied aspects of bioanalytical, materials and environmental
chemistry. We are interested in the design and development of chemical and biological
sensors that are inspired by the recognition processes found in nature. Perhaps
the best and most sophisticated recognition process is found in the human body.
For example, our senses of smell, tastes and ability to respond to temperature
variation all occur via living polymer interfaces. Even cellular processes are
regulated by cell walls, comprising dynamic macromolecules that are capable of
sensing and responding to specific chemical stimuli. Hence, by learning from
nature, we are developing smart sensors that can be used for applications in
environmental monitoring, homeland security, process control and biomedical
testing. Selected projects are discussed below.
Current Projects
Chemical Biosensors
The design of biosensors requires the successful immobilization of
biological reagents such as antigen, antibody, enzymes, DNA or cells. A number
of approaches for immobilizing antibody and dsDNA layers on electrodes have
been reported, yet the quest for a molecularly organized, but reproducible immobilization
continues to pose a challenge. A major research question is how to design the
interface between the transducer and the biospecific layer for efficient
molecular recognition. Basic questions include the exact nature of the
intermolecular forces at the sensor/biospecific layer and sensor/analyte
interfaces, and also whether these forces are responsible for the partial
discrimination between different chemical and biochemical compounds. The key is
to develop a molecular understanding of the sensor-analyte interactions to be
able to predict sensor characteristics even in complex mixtures. Understanding,
engineering and predicting the interactions between molecules require the
knowledge of the available types of interactions and a rational design of the
sensor chemistries.
Synthesis of Cross Selective Arrays of Polymers and Device
Fabrication
We are using different approaches to
fabricate conducting polymer membranes and hybrid polymer inorganic composites.
Examples include composites of poly (amic acid)-metallic gold, silver, cobalt
and palladium nanoparticles using pyromellitic dianhydride (PMDA) and
4,4’-oxydianiline (ODA).
Pattern
Recognition and Machine Learning:
We are exploring the effective use of polymer arrays coupled with
pattern recognition and machine learning for the detection and classification
of organophosphate nerve agents’ stimulants. For organophosphates and volatile organics, we showed a
significant 168% specificity improvement and a 40.5% positive predictive value
improvement using the s2000 kernels at 100% and 98% sensitivities when compared
to conventional system.
Bioelectrochemistry
We are
studying the theoretical and experimental approaches for monitoring the
interfacial biomolecular reaction using impedance spectroscopy. We have
demonstrated how to establish electrical communication between immobilized
antibodies (Abs) and the electrode
surfaces resulting in sensors having detection limits in the low pg/mL.
Opportunities exist to explore the use of surface plasmon resonance with
impedance spectroscopy as novel characterization tools.
Electroless and
Electrolytic Processes: We are also
studying novel plating techniques used in the fabrication of electronic
packages and chip-scale products. Electroless plating technique can be used to
metallize deep contact via for wirebond applications and for mounting chips to
chip carriers. We are using on-line sensors to assess bath performance and to
monitor the correlation between the bath chemistry and the overall quality of
plated circuitry.
Research
Collaborations
Our
group has active and ongoing research collaboration with the following:
Instrumentation & Laboratory Facilities
Sadik’s
group has over 2000 ft2 of space, located in 4 modern laboratories
in the Chemistry building. These laboratories are well equipped with
state-of-the art instrumentation and microfabrication tools. These include
eight modern electrochemical analyzers, 2 liquid chromatographs, gas
chromatography system, quartz crystal microbalances, numerous rotating disk
electrodes, three flow injection systems, small equipment (pH meters, balances,
refrigerators, ovens, etc.), five full-sized, four feet hoods and normal
glassware. Others include 14 Pentium-based PCs (for experimental control and
data processing).