UC Riverside

The detection of biomolecules, known as biosensing, has profoundly impacted biomedical diagnostics, disease monitoring/prevention, and food/water quality control. Despite the great strides in biosensing technology, there is still a drive to develop new biosensors that can improve current performance or solve emerging biosensing concerns. An emerging approach towards biosensing is using Whispering Gallery Mode (WGM) resonators. These devices are compact, highly sensitive, and require no additional fluorescent or radioactive tag, enabling real-time label-free biosensing. Polymer-based WGM cavities offer reduced material costs, simple processing strategies, and the potential for straightforward incorporation of bioreceptors in a single process step.Concurrently, filamentous bacteriophages such as the M13 bacteriophage have attracted attention as alternative bioreceptors. The length of the virus is comprised of 2700 copies of the same protein, which can each act as a bioreceptor. Crucially, this protein coat can be modified to display a wide range of specific binding motifs, creating a dense ordered arrangement of high-affinity peptides with the proper orientation for analyte binding. In this work I focus on the fabrication of WGM polymer/M13 bacteriophage sensors/biosensing using the near-field electrospinning process (NFES). NFES is a variant of electrospinning combining the high-volume, rapid manufacturing of electrospinning with precise patterning to fabricate microfibers. An advantage of NFES is the polymer-based approach can produce fibers that incorporate dyes and biomolecules such as M13 viruses. These electrospun fibers were first utilized as refractive index sensor in water-ethanol mixtures. The successful demonstration of WGM sensing spurred the fabrication of polymer/M13 biosensor where the M13 acted as a biorecognition element. The polymer/M13 fibers demonstrated specificity and sensitivity to the target analyte due to M13 on the fiber surface. Surface concentrations of M13 virus were increased during the NFES process by carefully tuning the M13 surface charge and electric field interactions. This work demonstrates the promise of NFES and electrospinning in fabricating WGM biosensors and highlights the use of M13 as a bioreceptor.