To test protein-ligand interactions, the key mechanisms for most drugs, without any external disturbances caused by molecular labelling or immobilization.
Protein ligand interaction is one of the most fundamental and widely studied areas in biology and chemistry because of their close relation to many diseases and disease therapies. Nearly all diseases including cancer, neural disorders, infectious diseases, cardiovascular diseases, renal diseases, metabolic diseases, immune diseases, etc. are connected to the abnormality of protein-protein or protein-ligand interactions. Unfortunately, all the current methods for in-vitro protein-ligand tests use either labels (often fluorescent) or ligand immobilization, both of which can produce substantial disruptions and introduce artifacts. These limitations have caused significant delay and cost increase in drug development. A new method is proposed and investigated to fundamentally solve the above problems, allowing precise in-vitro tests of the binding strength and kinetics of proteins ligand interactions to accelerate the process of drug discovery. The work can have significant impact on public health and the country's healthcare by shortening the time and saving the cost for drug discovery. The proposed research will also contribute to education and training of new generation of scientists for multi-disciplinary research involving biology, biochemistry, biophysics and engineering. The research also includes significant outreach activities to engage middle and high school students and underrepresented minority students to advance the STEM efforts.
Since a protein and ligand have a large molecular weight and size difference (e.g.,100 kDa versus 1 kDa), linking organic fluorescent molecules to a protein or ligand can perturb or even change the binding properties. Similarly, the bioactivity of protein depends on its 3D configuration. Immobilization of the molecules limits its degree of freedom for binding, thus often yielding results different from reactions in physiological conditions. Lacking a precise method of in-vitro detection of protein-ligand interactions without any external disturbances has presented a major challenge for mid to late stage drug tests. Drug companies have often conducted unnecessary and unsuccessful human trials while the failures should have been detected earlier if a precise in-vitro test method exists. The most significant scientific and technological contributions of the proposed research will be the development of the method of Transient Induced Electronic Molecular Spectroscopy (TIMES) that allows label-free and immobilization-free detection of protein-ligand interactions. The TIMES method measures the signal caused by the dipole moment change when protein and ligand form protein-ligand complex. When integrated with ultralow noise electronics and microfluidics, the new µTIMES system will enable researchers to collect unprecedented rich information with high timing resolution and enhanced signal-to-noise ratio. This method will be applied to quantitative studies of protein-ligand and protein-aptamer interactions by measuring the dissociation constant and reaction kinetics.
