DNA moves into photonics and electronics EU-funded scientists are developing novel biomaterials that promise to have a major impact on biodegradeable electronic applications. Energy © Thinkstock In the EU-funded project 'Functionalized biopolymers for application in molecular electronics and in photonics' (BIOMOLEC) scientists from leading laboratories throughout Europe are functionalising and doping well-known biopolymers such as DNA with photoactive chromophores. This should help develop materials with controllable charge mobility and with strong non-linear optical properties. Project members have already synthesised five push–pull chromophores at gram scale for doping the biopolymers. After incorporation in two different thin-film polymer matrices (PMMA and DNA-CTMA), they were evaluated for their luminescent properties, with DNA-CTMA exhibiting greater quantum yield. A number of different types of polymer–DNA composites have been prepared and synthesised by electropolymerisation. DNA-CTMA was found to be more electroactive, with double-layer capacity being three times greater than that of a pure polymer. Rendering DNA conducting capability, with controlled charge mobility, makes such polymer materials useful for molecular electronics applications, especially for field-effect transistors. To obtain nanorods and wire nanostructures, scientists have used the hydrothermal method, thus obtaining highly crystalline structures. The nanorods were deposited on substrates through a spin-coating technique, showing relatively homogeneous surface coverage without segregation. Oxidation and reduction processes — electron loss and gain — occurring in the coating could thus be observed. Having a great impact on the photorefractive properties of conjugated organic systems, nano objects can change the non-linear optical properties of such systems. This finding is important for strengthening matrix inorganic materials and creating a new contactless method for orienting vertically liquid crystal molecules in display devices. Project findings are important for fields as diverse as optical signal processing, molecular electronics and solar energy conversion. Development of new materials and of knowledge in biodegradable and renewable materials will prove fruitful as the 21st century is considered to be the century of photonics. Keywords Biopolymers, DNA, photonics, molecular electronics, doping, chromophores, charge mobility, non-linear optical, polymer matrices, quantum yield, field-effect transistors, spin-coating, photorefractive, energy conversion
