Chakraborty AK, Roy T and Mondal S
DNA is hereditary material with simple and stable building blocks of phosphate- 2’deoxy ribose-organic nitrogenous base with unique 3-D structure with AT-GC paring of two anti-parallel strands. DNA in solid or solution is a good carrier of electrons and biocompatable with binding efficiency to many proteins, organic molecules and metal ions. With the advent of nanotechnology in silver-gold nanoparticles and carbon nanoparticles, DNA has now been utilized as good source of nanotechnology material. In DNA nanotechnology, Watson-Crick DNA molecules are arranged into variety of nanostructures in the range of 10-100 nm size under special physical conditions due to electrostatic attraction among free electrons of sugar and phosphate oxygen and base nitrogen. However, different cohesive or sticky ends or loop structures among oligonucleotide staple strands have helped to make 3-D DNA nanostructures with various shapes. Holiday junction formation during crossover of chromosomes is the basis of DNA nanotechnology as millions fold compacted 3-D DNA structure is inherited in DNA itself. DNA tiles are hydrogen bonded few oligonucleotides which have cross sharing among themselves at the both ends. DNA-origami is principle when one big single stranded circular DNA crossovers with hundreds of short antisense oligonucleotide staple strands at different positions giving different shapes. In principle, when DNA tiles or DNA origami are allowed to crystal formation at 90°C to 4°C transition in presence of 10-20 mM MgCl2, DNA nanocrystals are formed. Thus, gold and silver as well as many drugs were impregnated in the DNA nanocages that were targeted to many pathogens and cancer cells. Such co-crystallised nano-drug delivery system also has been integrated to antisense/ribozyme/dicer molecular medicine. Recently, solid DNA nanotechnology applications combining DNA with proteins or cellulose and cross-linked with streptavidin-biotin are used in nanochip, nanosensor and nano-robotic technologies.
