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, process control and biomedical testing. 

Interfacial Studies based on Electroless & Electrochemical Deposition

Our Group has extensive expertise in interfacial reaction at metal-metal surfaces using electroless plating and has specifically studied the mechanism of electroless gold, nickel and cobalt. We employ a combination of surface, structural and morphological techniques to monitor the interfacial reactivity and plating rates, including electrochemical quartz crystal microbalance (EQCM), scanning electron microscopy (SEM), energy-dispersive spectroscopy (EDS), and X-ray photoelectron (XPS) analysis. We have also developed EQCM based mass sensor arrays for correlating the bath chemistry with the overall plating quality on industrial wirebond samples.

            We have shown that the mechanism of electroless gold deposition follows a multi-step electron transfer process during the oxidation of dimethylamine borane (DMAB) on gold in alkaline media. According to this mechanism, the initial chemical step is the S_N2 substitution reaction of DMAB with OH^- leading to the formation of the active reducing agent, trihydrohydroxy borate ion, BH₃OH^-, which depends on the pH of the solution. The resulting BH₃OH^- species undergoes a series of irreversible electrochemical oxidation producing the following intermediates BH₂(OH)₂^-, BH(OH)₃^- and B(OH)₄^-, the latter of which is the final product. The number of electrons transferred in each oxidation wave of DMAB in hydroxide was calculated and confirmed using the rotating disk electrode (RDE). When the KOH concentration is less than the dimethylamine-borane complex, the diffusion rate of hydroxide might be rate-limiting.

 

State-of-the-art 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, some of which can be viewed here below:

Biosensors                       

Electrochemistry            

Electrochemistry II            

Materials_Synthesis       

Mass_Spectrometry           

Sample_Preparation                   

Chromatography

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).

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.

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.

Collaborators
Our group has active and ongoing research collaboration with the following:

• Professor Joe Wang, University of California, San Diego.
• Professors Jim Melvin and Bedi Gurrinder, University of Rochester, Rochester, NY
• Professor Hector Abruña, Cornell University
• Professor Walker Land, SUNY-Binghamton
• Professor Qinru Qiu, SUNY-Binghamton
• Dr. Eugen Gherghiou, Director, UNESCO International Center of Biodynamics, Bucharest, Romania.
• Professor Ozsoz's Group at Ege University, Izmir (Ephesus), Turkey.
• Professor Shin-ichiro Suye, Fukui University, Japan