Rashid Amin

DNA nanotechnology: a future perspective.

In addition to its genetic function, DNA is one of the most distinct and smart self-assembling nanomaterials. DNA nanotechnology exploits the predictable self-assembly of DNA oligonucleotides to design and assemble innovative and highly discrete nanostructures. Highly ordered DNA motifs are capable of providing an ultra-fine framework for the next generation of nanofabrications. The majority of these applications are based upon the complementarity of DNA base pairing: adenine with thymine, and guanine with cytosine. DNA provides an intelligent route for the creation of nanoarchitectures with programmable and predictable patterns. DNA strands twist along one helix for a number of bases before switching to the other helix by passing through a crossover junction. The association of two crossovers keeps the helices parallel and holds them tightly together, allowing the assembly of bigger structures. Because of the DNA molecules unique and novel characteristics, it can easily be applied in a vast variety of multidisciplinary research areas like biomedicine, computer science, nano/optoelectronics, and bionanotechnology.

The label free DNA sensor using a silicon nanowire array

Biosensors based on silicon nanowire (Si-NW) promise highly sensitive dynamic label free electrical detection of various biological molecules. Here we report Si-NW array electronic devices that function as sensitive and selective detectors of as synthesized 2D DNA lattices with biotins. The Si-NW array was fabricated using top-down approach consists of 250 nanowires of 20 μm in length, equally spaced with an interval of 3.2 μm. Measurements of photoresistivity of the Si-NW array device with streptavidin (SA) attached on biotinylated DNA lattices at different concentration were observed and analyzed.. The conductivity in the DNA lattices with protein SA shows significant change in the photoresistivity of Si-NW array device. This Si-NW based DNA sensor would be one of very efficient devices for direct, label free DNA detection and could provide a pathway to immunological assays, DNA forensics and toxin detection in modern biotechnology.

A two-dimensional DNA lattice implanted polymer solar cell

A double crossover tile based artificial two-dimensional (2D) DNA lattice was fabricated and the dry-wet method was introduced to recover an original DNA lattice structure in order to deposit DNA lattices safely on the organic layer without damaging the layer. The DNA lattice was then employed as an electron blocking layer in a polymer solar cell causing an increase of about 10% up to 160% in the power conversion efficiency. Consequently, the resulting solar cell which had an artificial 2D DNA blocking layer showed a significant enhancement in power conversion efficiency compared to conventional polymer solar cells. It should be clear that the artificial DNA nanostructure holds unique physical properties that are extremely attractive for various energy-related and photonic applications.

NANOBIOTECHNOLOGY: AN INTERFACE BETWEEN NANOTECHNOLOGY AND BIOTECHNOLOGY

Nanotechnology is one of the most important emerging fields of science in this century. It deals with designing, construction, investigation, and utilization of systems at the nanoscale. Another interesting research discipline of current day is biotechnology, which gives us a way to understand biological system and to utilize our knowledge for industrial manufacturing. Nanobiotechnology lies at the interface of these two research fields. It exploits nanotechnology and biotechnology to analyze and create nanobiosystems to meet a wide variety of challenges and develops a wide range of applications.

Quantitative analysis of molecular-level DNA crystal growth on a 2D surface

Crystallization is an essential process for understanding a molecules aggregation behavior. It provides basic information on crystals, including their nucleation and growth processes. Deoxyribonucleic acid (DNA) has become an interesting building material because of its remarkable properties for constructing various shapes of submicron-scale DNA crystals by self-assembly. The recently developed substrate-assisted growth (SAG) method produces fully covered DNA crystals on various substrates using electrostatic interactions and provides an opportunity to observe the overall crystallization process. In this study, we investigated quantitative analysis of molecular-level DNA crystallization using the SAG method. Coverage and crystal size distribution were studied by controlling the external parameters such as monomer concentration, annealing temperature, and annealing time. Rearrangement during crystallization was also discussed. We expect that our study will provide overall picture of the fabrication process of DNA crystals on the charged substrate and promote practical applications of DNA crystals in science and technology.

Size‐Controllable DNA Rings with Copper‐Ion Modification

by simple molecular modi-fication, it makes DNA nanostructures one of the most viable biomaterials for use with current techniques. Although many developments took advantage of these characteristics, what has been lacking in DNA nanotechnology is sufficient investi-gation into specific interactions between DNA nanostructures and metal ions. Due to DNA’s poor conductivity,

Graphene-Based Waveguides: Novel Method for Detecting Biological Activity

We demonstrate the fabrication of a biosensor based on graphene coupled with polydimethylsiloxane (PDMS) waveguide. Biosensors work on the principle of local evanescent graphene-coupled wave sensor. It is observed that the evanescent field shifts in the presence of chemical or biological species as evanescent waves are extremely sensitive to a change in refractive index. This method helps to monitor the target analyte by attaching the selective receptor molecules to the surface of the PDMS optical waveguide resulting in its optical intensity distribution shift. We monitor the electrical properties of graphene in the dark and under illumination of PDMS waveguide. The changes in photocurrent through the graphene film were monitored for blue, green, and red light. We observed that the fabricated graphene-coupled PDMS optical waveguide sensor is sensitive to visible light for the used bioanalytes.

ARTIFICIALLY DESIGNED DNA NANOSTRUCTURES

In the field of structural DNA nanotechnology, researchers create artificial DNA sequences to self-assemble into target molecular superstructures and nanostructures. The well-understood Watson–Crick base-pairing rules are used to encode assembly instructions directly into the DNA molecules. A wide variety of complex nanostructures has been created using this method. DNA directed self-assembly is now being adapted for use in the nanofabrication of functional structures for use in electronics, photonics, and medical applications.

Growth and restoration of a T-tile-based 1D DNA nanotrack

We designed an artificial one-dimensional DNA nanotrack that contains two T-motifs. It can be fabricated in a free solution and with a mica-assisted growth process. Also, we introduced a dry and wet method for the restoration of DNA nanostructures in order for them to be used in multiple applications.

Intrinsic DNA curvature of double-crossover tiles

A theoretical model which takes into account the structural distortion of double-crossover DNA tiles has been studied to investigate its effect on lattice formation sizes. It has been found that a single vector appropriately describes the curvature of the tiles, of which a higher magnitude hinders lattice growth. In conjunction with these calculations, normal mode analysis reveals that tiles with relative higher frequencies have an analogous effect. All the theoretical results are shown to be in good agreement with experimental data.