Facilities Patents Educational Innovations Prior Research
Engineering microbiome interactions by real-time tracking of microbial phenotypesInteractions across the microbiome are an integral feature in controlling the emergence of infections, but monitoring and micro-engineering such interactions are a major challenge. The conventional microbial growth rate approach at various stages of microbial co-culture takes significant time for discernible results and does not work well with "unculturable" microbial strains. Immuno-assays require specific proteomic targets and are unsuited to real-time monitoring needs, due to the need for multiple incubation and wash steps. Our group has developed a label-free dielectrophoretic (DEP) technique for monitoring interactions across the microbiome based on alterations in the inherent electrophysiology and phenotype of each microbial strain, thereby providing means for micro-engineering of nutrient and environmental conditions to influence the microbiome. Alongside, we seek to develop in-situ monitoring approaches for cytokines from antigen presenting cells to enable the development of biomimetic adjuvants with well-modulated immune-reactions to enhance the influence of vaccines.
Selecting stem-cell lineages for developing cancer and transplant therapies A key challenge in tissue regeneration is the engineering of highly integrated assemblies, including hierarchical micro-vasculatures, nerve structures and muscle fibers along with specialized bone, ligament or cardiac cell types that serve particular functions. Stem cells are integral to the development of such complex assemblies, since they can be initiated to differentiate towards successively complex lineages for engineering integrated biosystems. However, current methods based on feeder cells, nutrients, and cues to the micro-environment are unable to definitively control stem cell differentiation due to the occurrence of fractional subpopulations. Using dielectrophoresis at radio frequencies as a label-free method to monitor and separate these particular stem cell subpopulations based on the characteristic frequency response of their electrophysiology, we seek to promote stem cell differentiation towards specific lineages, as well as to select particular subpopulations as transplants for therapeutic applications.
Electrically-mediated complex tissue regeneration Inherent to regenerating complex organs of more than one tissue type is the challenge of regenerating the interface between the tissues, so that neighboring tissues can ultimately function as one unit. Recently, we have obtained an opportunity to collaborate with Dr. Laurencin's orthopedics team (Connecticut Health Center) to examine the muscle and tendon of the rotator cuff (RC) of the shoulder as a test bed for complex tissue regeneration. Using pulsed electromagnetic fields and imprint lithography, we have fabricated scaffolds patterned with biocompatible conducting polymers for supporting various cell types. We seek to utilize these conducting polymeric regions to steer the electric fields towards healing muscle atrophy and reducing fatty infiltration for enabling differentiation of implanted stem cells into muscle cells. In conjunction, we seek to develop a feedback system for actively monitoring muscle regeneration by surface electromyography (sEMG) measurements in parallel to the electrical stimulation.
Conformation-specific biomarker enrichment and detection The diagnosis of diseases and detection of their pathogenesis requires the quantification of a spectrum of closely related biomarkers, which are present in extremely small quantities (~ng-pg/mL). We seek to selectively enrich particular biomarkers over other proteins in the bio-fluid media, by applying frequency-selective electrokinetic methods, such as dielectrophoresis (DEP), on a nano-slit device platform. While dielectrophoresis has been extensively applied towards sorting of similar sized biological cells with differing dielectric frequency response, its application to low polarizability biomolecules and nanostructures, especially within physiological media is unprecedented, since the trapping forces fall cube-fold with particle size and are overpowered by disruptive flow due to localized Joule heating. A set of advances from my group have overcome this limitation. First, we showed that electrode-less micro- and nano-constriction device geometries can be applied to locally enhance the field for a given applied AC bias, thereby enabling the trapping and enrichment of smaller biomolecules. Second, we developed means to construct constrictions within channels of nanoscale depth to reduce the disruptive effects of localized Joule heating in physiological media. Most recently, we demonstrated the application of AC dielectrophoresis in conjunction with DC ion concentration polarization for controlling the charge asymmetry at permselective nano-constrictions to cause ultrafast million-fold concentration enrichment of biomarkers selected based on their frequency response, while enabling separations based on differences in electrokinetic mobility (uEK).