The Park group’s research focuses on developing methods to control the organization of nanoparticles and polymers and to construct functional hybrid materials with controllable structure and properties. In particular, we use biomimetic approach to control the arrangement of nanoparticles and polymers of various compositions (e.g., conjugated polymers, peptides, and DNA). Our primary interest is to learn how to manipulate properties of inorganic nanoparticles, optoelectronic polymers, and DNA through the self-assembly.

So-Jung Park
Professor - Department of Chemistry and Nanoscience, Ewha Womans University

 Dr. So-Jung Park is a professor in the department of chemistry and nanoscience at Ewha womans university. She obtained her Ph.D. in Chemistry at Northwestern University in 2002 under the guidance of Prof. Chad Mirkin with a thesis on DNA-mediated assembly of nanostructured materials: structure, properties, and biodetection applications. Her PhD work was recognized by several prestigious awards including the ACS Nobel signature award. She then carried out her postdoctoral research with Prof. Paul Barbara at University of Texas at Austin, where she developed a new technique that allows for single molecule optical measurements correlated with electrical modulation for photophysical studies of semiconducting polymers and nanocrystals. She joined the faculty of the department of chemistry at the University of Pennsylvania as an assistant professor in the fall of 2005 and promoted to an associate professor with tenure in 2012. She then moved to Ewha woman’s university as a professor in 2013. Her research focuses on self-assembly of nanoparticles and functional polymers and their applications in biomedicine and optoelectronic devices. Her current research topics includes 1) colloidal self-assembly of nanoparticles and block-copolymers, 2) functional block copolymers (e.g., DNA, conjugated polymers), 3) plasmonic nanoparticles, and 4) dynamic nanostructures. The research projects aim to understand collective behaviour of nanomaterials and to develop new functional materials through self-assembly. She has received the NSF career award, ARO young investigator award, and Camille Dreyfus Teacher Scholar Award. She is serving as an associate editor for ACS Applied Materials & Interfaces and an advisory board member for Nanoscale.

01. Nanoparticle-Directed Self-Assembly of Block Copolymers

Superparamagnetic Polymersomes
The incorporation of nanoparticles induce interesting morphology changes in self-assembly of amphiphilic polymers. For example, we have fabricated polymersomes densely packed with magnetic nanoparticles through cooperative self-assembly of nanoparticles and micelle-forming polymers. The superparamagnetic polymersomes exhibited significantly enhanced magnetic relaxivity than typical micellar structures. [Angew. Chem. Int. Ed. 2007, 46, 48, 9235-9238, JACS, 2011, 133, 1517-1525, ACS Nano, 2013, 7, 5824, ACS Nano. 2014, 8, 495-502.]

Nanoporous Films
We investigated self-assembly of nanoparticles and block copolymers at the air-water interface, which led to the formation of highly uniform composite films with interesting nanoscale porous structures. [ACS Nano, 2020, 14, 12203.]

02. Self-Assembly of Conjugated Block-Copolymer

Hierarchical Self-Assembly of Conjugated Block-Copolymers
Solution phase self-assembly of P3HT-b-PEO led to various types of hierarchical assembly structures of P3HT nanofibers, demonstrating that the supramolecular self-assembly of conjugated polymers provides a new toolbox for the formation of functional organic nanostructures. [JACS, 2010, 132, 9931, ACS Nano. 2012, 6, 2844]

Air-Liquid Interfacial Self-Assembly of Conjugated Block-Copolymers
Interfacial self-assembly of P3HT-b-PEO was used to fabricate ultrathin conjugated polymer films composed of well-aligned P3HT nanowires. Furthermore, binary self-assembly with functional nanoparticles led to ordered arrays of functional nanoparticles and polymers with improved transport properties. [ACS Nano 2014, 8, 12755, ACS AMI 2019, 11, 28538, ACS AMI 2020, 12, 5099, ACS AMI 2022]

03. DNA Block-Copolymers

Low-Dimensional DNA Nanostructures
Unusual low-dimensional DNA nanostructures were fabricated from DNA-b-poly(amino acid) through programmable and sequence-specific peptide interactions. Unlike prototypical DNA block copolymers, which typically form simple spherical micelles, DNA-b-poly(amino acid) assemble into various low-dimensional structures such as nanofibers, ribbons, and sheets through controllable amino acid interactions (ACS Nano 2020, 14, 2276).

Janus Nanosheets
Janus DNA nanosheets were fabricated from molecular building blocks composed of two information-carrying biopolymers, DNA and peptides. Experimental and structural modeling studies reveal that DNA1-peptide-DNA2 conjugates assemble into Janus nanosheets presenting two different DNA on opposite faces. The surprising level of structural control is attributed to the exclusive parallel β-sheet formation of phenylalanine-rich peptides. (Small 2021, 17, 2006110).

04. Plasmonic Nanoparticles

Spiky Gold Nanoshells
We developed a new synthetic method for metal nanoshells with highly structured surface. They exhibit enhanced near-field and far-field scattering compared to widely studied smooth shells and serve as highly reproducible and bright surface-enhanced Raman scattering (SERS) substrate. [J. Phys. Chem. C 2012, 116, 10318(Featured on the journal cover), ACS Nano, 2014, 8, 9, 9025-9034.]

Metamolecules
Assembly of metal nanoparticles can bring about unusual metamaterial properties that are rarely observed in our surroundings. The synthetic method allows for simultaneous synthesis and assembly of nanoparticles to fabricate raspberry-like metamolecules supporting strong magnetic resonances. [ACS Nano 2015, 9, 1263, J. Phys. Chem. C 2020, 124, 20436?20444(Editor's choice), Adv. Mater. 2021, 2007668.]

05. DNA-Mediated Layer-by-Layer Assembly for Dynamic Nanostructures

Responsive Free-Standing Nanoparticle Films
Responsive free standing films of gold nanoparticles were fabricated by a new approach based on the programmable DNA-directed self-assembly and the layer-by-layer (LbL) thin film fabrication technique. [Nano Lett., 2013, 13, 4449, Nat. Nanotech., 2017, 12, 41]. We further combined the strategy with plasmonic photopatterning to fabricate nanoparticle films with vertical and lateral heterogeneity, which showed complex morphing actions instructed by the lateral and vertical patterns inscribed in the film as well as the information carried in DNA [Adv. Mater., 2022].