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Abstract

The equilibrium adsorption of three nucleic acids: chromosomal DNA, supercoiled plasmid DNA, and 25S rRNA, on the clay minerals, montmorillonite (M) and kaolinite (K), were studied. Adsorption of the nucleic acid on the clays was rapid and maximal after 90 min of contact time. Chromosomal DNA was adsorbed to a greater extent than plasmid DNA and RNA, and the adsorption was also greater on M than on K. Adsorption isotherms were of the L type, and a plateau was reached with all the complexes, with the exception of chromosomal DNA adsorbed on M. To deterine where nucleic acids are adsorbed on clay minerals and the nature of the interaction, complexes were studied by X-ray diffraction (X-RD), electron microscopy, and Fourier transform infrared (FT-IR) spectroscopy. X-RD showed that nucleic acids did not penetrate the clay, indicating that the adsorption occurred primarily on the external surfaces of clay particles, as also suggested by electron microscopy observations. FT-IR spectra of clay-tightly bound nucleic acid complexes showed adsorption bands that indicate a variation of the nucleic acids status as a consequence of their adsorption on clay. Data obtained suggested that the formation of clay-nucleic acid complex could have an important role in the preservation of genetic material in primeval habitats.

Analysis of Oligonucleotide DNA Binding and Sedimentation Properties of Montmorillonite Clay Using Ultraviolet Light Spectroscopy

“…Determination of the mechanism by which nucleic acids interact with clays found naturally in soils is important for understanding how extracellular DNA might be preserved in the environment and also how it may be transferred between organisms over time 9. In addition, clays have been used successfully as vectors for delivery of DNA into cells in recent experiments 10-12.…”

“…In addition, clays have been used successfully as vectors for delivery of DNA into cells in recent experiments 10-12. The binding of single-stranded or double-stranded DNA polymers to the large, negatively charged surfaces of montmorillonite particles is poorly understood, but is thought to be affected by pH and the concentration and nature of the metal cations that are present 9,13. Strands of DNA possess a strong negative charge due to the phosphate groups present on each nucleotide monomer.…”

“…In these experiments, DNA (nucleotides, single-stranded or double-stranded) and clay were mixed in aqueous solution and centrifuged at various speeds (typically between 15,000 and 40,000 × g) to pellet the clay plus any bound DNA molecules 9,11,13-24. Residual absorbance of the supernatant at 260 nm then permitted calculation of the concentration of unbound DNA.…”

Adsorption of L-amino Acids on Sea Sand

“…There are many studies on the adsorption of amino acids [2][3][4][5][6] as well as other biomolecules, 7,8 and biopolymers [9][10][11][12][13] on clays. Clays were used in many experiments because they have a large surface-area-to-volume ratio in comparison with quartz or sand whose surface-area-to-volume ratios are small.…”

Protective Effect of Montmorillonite on Plasmid DNA in Oral Gene Delivery into Small Intestine

“…The structure is an octahedral laminated sheet sandwiched between tetrahedral silicate layers. Since the interaction between clay and DNA has been well studied using montmorillonite, 7,8) we chose this mineral in this study to evaluate as a novel vector for an oral gene delivery system.…”