UC Riverside

Surface plasmon resonance (SPR) has been widely used as a powerful analytical technique for the study of a broad range of biomolecular interactions. With the capability of real-time detection, SPR allows convenient and nondestructive measurement of analyte concentration and binding kinetics. To improve the performance of SPR biosensing, we have developed a series of novel methods that lead to ultrasensitive detection via signal amplification by coupling inline atom transfer radical polymerization (ATRP) to a biospecific interaction. To adapt this enhancement method to the fragile lipid membrane-based system, initiator functionalized gold nanoparticles (AuNPs) has been used with in situ ATRP reaction, which allows sensitive measurement of lipid membrane binding proteins. In addition, conjugated nanoparticles AuNPs and Fe3O4 NPs have been employed to enhance protein detection sensitivity with SPRimaging. A novel Au-well microarray, fabricated based on spatial variation of metal thickness, is utilized to eliminate background resonance and provide better performance.

To mimic cell membrane recognition processes, a membrane bilayer has been assembled onto a nanoglassified surface, and a synthesized water-soluble deep cavitand was incorporated into the supported lipid membrane. The incorporated cavitand retains its host properties and real-time analysis of the host:guest properties is carried out by SPR and fluorescence microscopy. To further explore the biomolecule interactions on cell membrane, we have studied the polymer growth at the lipid membrane-water interface using functional guest initiator that triggers an ATRP process. A variety of functional polymers have been grown at the lipid membrane surface, demonstrating different hydrophilicity and protein binding properties.

Mass spectrometry in combination with SPR for comprehensive protein analysis has been explored to build a new technical platform. We have designed a thermoresponsive poly(N-isopropylacrylamide) (PNIPAAM) grafted surface, which demonstrates temperature-mediated hydrophobicity for enrichment of proteins based on hydrophobic interaction. SPR quantitatively measures the binding of proteins and peptides, and the biochip is directly interfaced with matrix assisted laser desorption/ionization (MALDI)-MS to characterize the bound analytes. It provides outstanding results in simple steps of on-plate desalting, offering news tools for effective proteomic analysis.