(1) Current Research: Targeted emissive polymersomes are biocompatible nanocarriers that have the enormous potential for in vivo imaging, diagnostics, and drug delivery applications. For example, imaging of cancer or inflammatory cells can be dramatically improved by attaching chemical compounds to emissive polymersomes that selectively bind to chemical markers on surfaces of these cells. In this work, we use NIR emissive polymersomes comprised of self-assembled amphiphilic diblock copolymers and hydrophobic porphyrin-based NIR fluorophores (NIRFs). These polymersomes have several distinguishing characteristics; (1) both the polymer and porphyrin-based NIRF are fully biocompatible; (2) polyethylene-oxide (PEO) head groups result in long in vivo circulation times and also available for coupling to biomolecules; (3) thickness (9-22nm) and mechanical strength of membrane can be adjusted to incorporate a wide range of both hydrophobic and hydrophilic compounds; (4) vesicle sizes are tunable from 50 nm to 10 um in diameter; (5) porphyrin-based NIRFs possess highly attractive and sensitive emissive spectra (700-950nm), where light is not absorbed by tissue and can penetrate deep into it; and (6) poly(ethylene oxide-b-caprolactone) based polymersomes hydrolyze over time for controlled release of molecules.

(2) Doctoral Research (with John C. Crocker, University of Pennsylvania): My doctoral research was focused on assembling novel colloidal crystal structures using DNA-mediated interaction. In order to expand the kind of structures that can be formed with simple spheres, specific interactions between different species in a binary mixture have been predicted to promote novel crystal formation. For instance, by surface functionalizing colloids with engineered DNA sequences we can control the range and magnitude of interparticle interaction and lead them to assemble in ways we want. We have developed a novel swelling/deswelling method for modifying the surface of colloids with a polymer brush and functional groups to make sterically stable DNA-grafted colloids that sucessfully assemble into close-packed colloidal crystal structures. In addition, we have studied crystal growth in a simple colloidal alloy: a binary solid solution, in which a minority species is randomly inserted into a lattice of the majority species as a substitutional impurity. A competition between DNA single-base mismatches was used to create a very small interaction strength mismatch that provided us with a view of the growing crystals' interfacial thermodynamics. Depending on the free energy difference, we found either complete exclusion of the minotrity species or a finite segregation coefficient.