Seo-Young Kwak

Cellular uptake behavior of [γ-32P] labeled ATP–LDH nanohybrids

The inorganic layered double hydroxide support, Mg4Al2(OH)12(NO3)2·mH2O, could be obtained by coprecipitation in aqueous solution; the interlayered NO3− anions can be replaced by biomolecules such as cytidine 5′-monophosphate, adenosine 5′-monophosphate, guanosine 5′-monophosphate and adenosine 5′-triphosphate to form new biomolecule–LDH hybrids. Upon intercalating these biomolecules into hydroxide layers, the interlayer distance increases from 8.7xa0A n(for NO3−) to 14.5xa0A, 16.9xa0A, 18.4xa0A, and 19.4xa0A, respectively. According to spectroscopic analysis, it is also found that the intercalated biomolecules maintain their chemical properties unchanged in the interlayer space of the layered double hydroxide. Furthermore, the nisotope dilution test for the transfer efficiency of [γ-32P] ATP–LDH hybrid into eucaryotic cells verifies reproducibly much higher transfer efficiency of the hybrid than for ATP molecules alone due to the charge neutralization of anionic phosphate molecules by cationic hydroxide layers in the hybrid. These experimental data suggest the potential usefulness of LDHs as innovative inorganic reservoirs and delivery carriers for genes, drugs, and other biomolecules.

Bio-LDH nanohybrid for gene therapy

Abstract Nano-sized inorganic clay, such as layered double hydroxide (LDH), has been demonstrated as delivery carrier for genes and drugs by hybridizing with DNA and c-antisense oligonucleotide (As- myc ). Upon intercalating biomolecules into hydroxide layers, the basal spacing of LDH increases from 8.7 A (for NO 3 − ) to 23.9 A (DNA) and 17.1 A (As- myc ), respectively. A strong suppression of cell growth (65%) is observed when the HL-60 cells are incubated with 20 μM As- myc –LDH hybrid. However, LDH itself is found to be noncytotoxic on HL-60 cells (leukemia cells). Based on these findings, it is proved that LDHs can act as a new inorganic carrier which is completely different from ever existing nonviral vectors in terms of its chemical bonding and structure.

New organo-montmorillonite complexes with hydrophobic and hydrophilic functions

Quaternary alkylammonium cations (R4N+) with different molecular structures were intercalated into layered aluminosilicate, Na+-montmorillonite (M), by ion exchange reaction. Four kinds of R4N+ molecular ions, [(CH3(CH2)17)xN(CH3)4 − x]+ with x = 1 (ODTM) and x = 2 (DMDS) and [(CH3(CH2)15COO(CH2)2)xN(CH3)(CH2CH2OH)3 − x]+ with x = 1 (DHMC) and x = 2 (DCEM), were used as intercalants. The relative dispersibility of intercalated R4N+M samples in polar and nonpolar solvents were evaluated on the basis of viscosity. Even in an aqueous solution, the DHMC-M and DCEM-M complexes, exhibited good dispersibility due to the hydrophilic functional groups in the organic cations. On the other hand, the DMDS-M and ODTM-M complexes containing only aliphatic long chain showed enhanced dispersibility in nonpolar solvents like n-hexane.

Layered double hydroxide as gene reservoir

Abstract Novel bio-/organic-inorganic hybrid compounds of deoxyribonucleic acid (DNA) and methotrexate (MTX)-layered double hydroxide are prepared by ion-exchange type intercalation reaction. The layered inorganic support. Mg2Al(NO3)-LDH, is at first obtained by coprecipitation in an aqueous solution, and then the interlayer NO3 − anions are replaced by guest molecules such as methotrexate (an anticancer drug) and deoxyribonucleic acid (about 500 ∼ 1000 base pairs), leading to form new bio-/organic-nanohybrids. Upon intercalating guest molecules into hydroxide layers, the basal spacing of LDH increases from 8.5 Å (NO3 −) to 20.8 Å (MTX) and 23.9 Å (DNA), respectively. According to the X-ray diffraction and infrared spectroscopic analyses, it is found that the target molecules are safely preserved by hydroxide layers maintaining their chemical and structural properties.

Insertion of Inorganic-Biomolecular Nanohybrid into Eucaryotic Cell

Abstract : It has been clearly demonstrated that ATP could be intercalated into inorganic layered double hydroxide (LDH), giving rise to a biomolecular-inorganic nanohybrid with preserving its physico-chemical and biological integrity. It shows a remarkable transfer efficiency of ATP into target cells by alleviating an electrical repulsion at the cell walls due to the neutralization of negative charge of phosphates by positive hydroxide layers. From cellular uptake experiment with laser scanning confocal fluorescence microscopy, it is revealed that the FTTC-LDH hybrid is effectively transferred into 293 cells. Such an unique feature of biomolecule-LDH hybrid will open a new field of reserving and delivering genes, drugs and other functional biomolecules.