Junghong Park

Supramolecular Inhibition of Amyloid Fibrillation by Cucurbit[7]uril

Amyloid fibrils are insoluble protein aggregates comprised of highly ordered β-sheet structures and they are involved in the pathology of amyloidoses, such as Alzheimers disease. A supramolecular strategy is presented for inhibiting amyloid fibrillation by using cucurbit[7]uril (CB[7]). CB[7] prevents the fibrillation of insulin and β-amyloid by capturing phenylalanine (Phe) residues, which are crucial to the hydrophobic interactions formed during amyloid fibrillation. These results suggest that the Phe-specific binding of CB[7] can modulate the intermolecular interaction of amyloid proteins and prevent the transition from monomeric to multimeric states. CB[7] thus has potential for the development of a therapeutic strategy for amyloidosis.

A review of RGD-functionalized nonviral gene delivery vectors for cancer therapy

The development of effective treatments that enable many patients suffering from cancer to be successfully cured is highly demanded. Angiogenesis, which is a process for the formation of new capillary blood vessels, has a crucial role in solid tumor progression and the development of metastasis. Antiangiogenic therapy designed to prevent tumor angiogenesis, thereby arresting the growth or spread of tumors, has emerged as a non-invasive and safe option for cancer treatment. Due to the fact that integrin receptors are overexpressed on the surface of angiogenic endothelial cells, various strategies have been made to develop targeted delivery systems for cancer gene therapy utilizing integrin-targeting peptides with an exposed arginine–glycine–aspartate (RGD) sequence. The aim of this review is to summarize the progress and prospect of RGD-functionalized nonviral vectors toward targeted delivery of genetic materials in order to achieve an efficient therapeutic outcome for cancer gene therapy, including antiangiogenic therapy.

Polydopamine Hollow Nanoparticle Functionalized with N‐diazeniumdiolates as a Nitric Oxide Delivery Carrier for Antibacterial Therapy

A biocompatible nitric oxide (NO) delivery nanoplatform, whose structure is a hollow nanoparticle composed of polydopamine backbone and diazeniumdiolates functional groups, is developed for antibacterial therapy. This platform liberates high NO quantitis and exerts the antibacterial activity with excellent biocompatibility thus being promising for treating bacterial infections.

DNA-templated silver nanoclusters as label-free, sensitive detection probes for potassium ions and nitric oxide

DNA-templated silver nanoclusters (DNA-AgNCs) have emerged as promising materials for sensing, bio-labelling, and bio-imaging due to their fluorogenic properties. Using the 12 mer DNA with a cytosine-rich sequence, AgCNs have been formed successfully. Herein, we develop two different types of DNA-AgNC systems for the detection of potassium ions (K+) and nitric oxide (NO) by utilizing the structural change of DNA or DNA template transformation. In K+ detection, a thrombin binding aptamer (TBA) was utilized as both the AgNC template and the K+ binding probe. The fluorescence emission of the DNA1-AgNC probe was diminished proportionally to the amount of K+ detected, which transforms the AgNC-adapted structure into G-quadruplex. On the other hand, NO detection has been accomplished by NO-induced deamination of cytosine. The structural change of cytosine to deoxyuridine destabilizes the DNA2-AgNC structure, resulting in quenching of fluorescence intensity. The characteristics of these two highly quantitative detection probes were analysed by UV absorption, fluorescence emission, and transmission electron microscopy (TEM). Each system provides a detection limit of 6.2 μM for K+ and 0.1 μM for NO. We expect that these systems enable the opening of a new horizon for highly sensitive and selective detection systems.

Therapeutic-Gas-Responsive Hydrogel

Nitric oxide (NO) is a crucial signaling molecule with various functions in physiological systems. Due to its potent biological effect, the preparation of responsive biomaterials upon NO having temporally transient properties is a challenging task. This study represents the first therapeutic-gas (i.e., NO)-responsive hydrogel by incorporating a NO-cleavable crosslinker. The hydrogel is rapidly swollen in response to NO, and not to other gases. Furthermore, the NO-responsive gel is converted to enzyme-responsive gels by cascade reactions from an enzyme to NO production for which the NO precursor is a substrate of the enzyme. The application of the hydrogel as a NO-responsive drug-delivery system is proved here by revealing effective protein drug release by NO infusion, and the hydrogel is also shown to be swollen by the NO secreted from the cultured cells. The NO-responsive hydrogel may prove useful in many applications, for example drug-delivery vehicles, inflammation modulators, and as a tissue scaffold.

Hydro-nanofibrous mesh deep cell penetration: a strategy based on peeling of electrospun coaxial nanofibers

A two-step strategy for coaxial electrospinning and postelectrospinning is an effective method for fabricating superfine nanofibers composed of highly swellable hydrogels. Alginate and poly(ε-caprolactone) [PCL] were coelectrospun via fibrous meshes with a coaxial nozzle; alginate at the core was subsequently cross-linked in calcium chloride solution. The PCL sheath was removed from the meshes by repeated organic-phase washing. The peeling process was monitored by scanning electron microscopy, transmission electron microscopy, and differential scanning calorimetry, and the complete removal of the PCL outer layers was confirmed by the thinning of the fiber volume. The obtained alginate hydronanofiber showed extreme water-swellability and mass erosion depending on the degree of cross-linking. We also measured the nanoscale and macroscale mechanical properties of a single nanofiber and of the whole mesh by atomic force microscopy and rheometry. Quantitative analysis of nanomechanical properties indicated that the hydronanofiber with higher cross-linking density had higher stiffness and Derjaguin-Müller-Toporov modulus. Cells laid on the mesh and the vertical infiltration distance were visualized and quantified by confocal laser scanning microscopy. Cells on the mesh with higher cross-linking density infiltrated deeply to the bottom of the mesh. Thus, hydrogel-like nanofibrous meshes are versatile matrices allowing for deep infiltration of cells throughout the mesh via manipulation of the mechanical properties of the nanofiber.

Focusing X-ray free-electron laser pulses using Kirkpatrick–Baez mirrors at the NCI hutch of the PAL-XFEL

Microfocusing of hard X-ray free-electron laser pulses using Kirkpatrick–Baez mirrors at the nano-crystallography and coherent imaging hutch of the Pohang Accelerator Laboratory X-ray Free-Electron Laser facility is reported.