Sungjee Kim

Type-II band engineered quantum dots (CdTe/CdSe(core/shell) and CdSe/ZnTe(core/shell) heterostructures) are described. The optical properties of these type-II quantum dots are studied in parallel with their type-I counterparts. We demonstrate that the spatial distribution of carriers can be controlled within the type-II quantum dots, which makes their properties strongly governed by the band offset of the comprising materials. This allows access to optical transition energies that are not restri

We report a new family of oligomeric alkyl phosphine ligands for nanocrystal quantum dots. These oligomeric phosphines show effective binding affinity to quantum dot surfaces. They form thin and secure organic shells that stabilize quantum dots in diverse environments including serum and polymer matrices. They maintain the initial as-grown photoluminescence quantum yield of the quantum dots and enable homogeneous incorporation into various matrices. They present a chemically flexible structure t

Recently, lead halide perovskite (LHP) materials have shown potential for many optoelectronic applications. However, the structural instability and toxicity concerns necessitated robust and heavy-metal-free alternatives. We report a synthetic route to Cs2AgInCl6 double-perovskite nanocrystals (DP NCs) that have the crystal structure replacing two lead ions in LHP by a pair of silver and indium ions. Cubic-shaped Cs2AgInCl6 DP NCs were obtained with a narrow size distribution, which showed superi

Abstract A new type of quantum dot (QD) ligand chemistry is introduced that can provide positive, negative, or zwitterionic surface QDs. CdSe/CdZnS core‐shell QDs are decorated with ligands, and the non‐specific and specific interactions of the QDs through their surface charge are investigated with the focus on cellular adsorptions and endocytosis. Zwitterionic QDs are compact with a ligand hydrodynamic thickness of less than 2 nm, they are colloidally very stable over a broad pH range and even

A DNA hydrogel is reported as a delivery vehicle for gold nanorods and doxorubicin. The two photothermal and chemo cancer agents were co-loaded using electrostatic and DNA binding interactions, respectively. Light-triggered and highly synergistic combination cancer therapy was demonstrated in cellular and animal models.

'Smart' gold nanoparticles can respond to mild acidic environments, rapidly form aggregates, and shift the absorption to red and near-infrared. They were used as a photoacoustic imaging agent responsive to the cancer microenvironment, and have demonstrated the cancer-specific accumulation at the cellular level and an amplified signal which is twice higher than the control in vivo.

Assembled AuNPs in a DNA hydrogel (Dgel) showed strongly coupled plasmon modes, and the Dgel vehicle can co-load anticancer drugs such as doxorubicin (Dox) as a light-controlled releasing cargo by DNA intercalations. Upon laser excitation, local heat shock generation was accompanied by the release of Dox. A highly synergistic combination of thermo- and chemotherapy was demonstrated in cellular and animal models. Our Dgel vehicle can be fragmented after the excitation-induced heat generations, wh

Potential advantages of quantum dot (QD) imaging in the second optical window (SOW) at 1,000 to 1,400 nm over the first optical window (FOW) at 700 to 900 nm have attracted much interest. QDs that emit at 800 nm (800QDs) and QDs that emit at 1,300 nm (1,300QDs) are used to investigate the imaging depths at the FOW and SOW. QD images in biologic tissues are processed binarized via global thresholding method, and the imaging depths are determined using the criteria of contrast to noise ratio and r

We have studied the effect of the zwitterionic surface coating of quantum dots (QDs) on their interaction with a serum supplemented cell medium and their internalization by human cervical carcinoma (HeLa) cells. Zwitterionic QDs showed negligible adsorption of human serum albumin (HSA) selected as a model serum protein, in contrast to similar but negatively charged QDs. The incorporation of zwitterionic QDs by HeLa cells was found to be lower than for negatively charged QDs and for positively ch