A DNA tetrahedron is employed for efficient delivery of doxorubicin into drug-resistant breast cancer cells. The drug delivered with the DNA nanoconstruct is considerably cytotoxic, whereas free doxorubicin is virtually non-cytotoxic for the drug-resistant cells. Thus, the DNA tetrahedron, made of the inherently natural and biocompatible material, can be a good candidate for the drug carrier to overcome MDR in cancer cells.

Despite the promising photofunctionalities, phosphorescent probes have been examined only to a limited extent, and the molecular features that provide convenient handles for controlling the phosphorescence response have yet to be identified. We synthesized a series of phosphorescence zinc sensors based on a cyclometalated heteroleptic Ir(III) complex. The sensor construct includes two anionic cyclometalating ligands and a neutral diimine ligand that tethers a di(2-picolyl)amine (DPA) zinc receptor. A series of cyclometalating ligands with a range of electron densities and band gap energies were used to create phosphorescence sensors. The sensor series was characterized by variable-temperature steady-state and transient photoluminescence spectroscopy studies, electrochemical measurements, and quantum chemical calculations based on time-dependent density functional theory. The studies demonstrated that the suppression of nonradiative photoinduced electron transfer (PeT) from DPA to the photoexcited Ir(IV) species provided the underlying mechanism that governed the phosphorescent response to zinc ions. Importantly, the Coulombic barrier, which was located on either the cyclometalating ligand or the diimine ligand, negligibly influenced the PeT process. Phosphorescence modulation by PeT strictly obeyed the Rehm-Weller principle, and the process occurred in the Marcus-normal region. These findings provide important guidelines for improving sensing performance; an efficient phosphorescence sensor should include a cyclometalating ligand with a wide band gap energy and a deep oxidation potential. Finally, the actions of the sensor were demonstrated by visualizing the intracellular zinc ion distribution in HeLa cells using a confocal laser scanning microscope and a photoluminescence lifetime imaging microscope.

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A new glioblastoma (GBM) targeting peptide is developed and successfully demonstrated the delivery of a nano-therapeutic.

Photodynamic therapy (PDT) is a cytotoxic treatment using singlet oxygen produced by photosensitizers. Approved porphyrinoid PDT still suffers from a lack of robust production methods and low water solubility. Methylene blue (MB) is a good candidate for the PDT drug, because the dye is an effective photosensitizer, can be easily synthesized, and is already being used in other clinical fields. However, its poor cell/tissue penetration and low stability against the reducible biological conditions should be addressed by using a proper delivery vehicle. Here, we employed a DNA tetrahedron, a self-assembled nanostructure as the carrier for intracellular delivery of MB by taking advantage of the DNA binding property of the photosensitizer and demonstrated photo-induced cytotoxicity by the MB delivered by the DNA nanocarrier. We also evaluated the PDT potency of the MB-loaded DNA nanoconstruct in vivo tumor model to suppress tumor growth.

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Although rolling circle amplification (RCA) is an efficient method to produce DNA materials for biomedical applications, it does not yield nano-sized products suitable for intracellular delivery. We here provide the ways to control the size of RCA products and show a potential application of the size-controlled DNA nanoparticles.