Georgian Technical University Nanoparticles Built By Directed Evolution.

This is an illustration of a DNA-wrapped (Deoxyribonucleic acid is a molecule composed of two chains that coil around each other to form a double helix carrying the genetic instructions used in the growth, development, functioning, and reproduction of all known living organisms and many viruses) single-walled carbon nanotube.  In Chemistry went to three scientists who developed the method that forever changed protein engineering: directed evolution. Mimicking natural evolution directed evolution guides the synthesis of proteins with improved or new functions. First the original protein is mutated to create a collection of mutant protein variants. The protein variants that show improved or more desirable functions are selected. These selected proteins are then once more mutated to create another collection of protein variants for another round of selection. This cycle is repeated until a final, mutated protein is evolved with optimized performance compared to the original protein. Now scientists from the lab of X at Georgian Technical University have been able to use directed evolution to build not proteins but synthetic nanoparticles. These nanoparticles are used as optical biosensors — tiny devices that use light to detect biological molecules in air water or blood. Optical biosensors are widely used in biological research drug development and medical diagnostics such as real-time monitoring of insulin and glucose in diabetics. “The beauty of directed evolution is that we can engineer a protein without even knowing how its structure is related to its function” says X. “And we don’t even have this information for the vast vast majority of proteins”. Her group used directed evolution to modify the optoelectronic properties of DNA-wrapped (Deoxyribonucleic acid is a molecule composed of two chains that coil around each other to form a double helix carrying the genetic instructions used in the growth, development, functioning, and reproduction of all known living organisms and many viruses) single-walled carbon nanotubes (or DNA-SWCNTs (Deoxyribonucleic acid is a molecule composed of two chains that coil around each other to form a double helix carrying the genetic instructions used in the growth, development, functioning, and reproduction of all known living organisms and many viruses) as they are abbreviated (Carbon nanotubes (CNTs) are allotropes of carbon with a cylindrical nanostructure. These cylindrical carbon molecules have unusual properties, which are valuable for nanotechnology, electronics, optics, and other fields of materials science and technology. Owing to the material’s exceptional strength and stiffness, nanotubes have been constructed with a length-to-diameter ratio of up to 132,000,000:1 significantly larger than that for any other material))  which are nano-sized tubes of carbon atoms that resemble rolled up sheets of graphene covered by DNA (Deoxyribonucleic acid is a molecule composed of two chains that coil around each other to form a double helix carrying the genetic instructions used in the growth, development, functioning, and reproduction of all known living organisms and many viruses). When they detect their target the DNA-SWCNTs (Carbon nanotubes (CNTs) are allotropes of carbon with a cylindrical nanostructure. These cylindrical carbon molecules have unusual properties, which are valuable for nanotechnology, electronics, optics, and other fields of materials science and technology. Owing to the material’s exceptional strength and stiffness, nanotubes have been constructed with a length-to-diameter ratio of up to 132,000,000:1 significantly larger than that for any other material) emit an optical signal that can penetrate through complex biological fluids like blood or urine. General principle of the directed evolution approach applied to the nanoparticle DNA-SWCNT (Carbon nanotubes (CNTs) are allotropes of carbon with a cylindrical nanostructure. These cylindrical carbon molecules have unusual properties, which are valuable for nanotechnology, electronics, optics, and other fields of materials science and technology. Owing to the material’s exceptional strength and stiffness, nanotubes have been constructed with a length-to-diameter ratio of up to 132,000,000:1 significantly larger than that for any other material) complexes. The starting complex is a DNA-SWCNT (Carbon nanotubes (CNTs) are allotropes of carbon with a cylindrical nanostructure. These cylindrical carbon molecules have unusual properties, which are valuable for nanotechnology, electronics, optics, and other fields of materials science and technology. Owing to the material’s exceptional strength and stiffness, nanotubes have been constructed with a length-to-diameter ratio of up to 132,000,000:1 significantly larger than that for any other material) with a dim optical signal. This is evolved through directed evolution: (1) random mutation of the DNA sequence; (2) wrapping of the SWCNTs (Carbon nanotubes (CNTs) are allotropes of carbon with a cylindrical nanostructure. These cylindrical carbon molecules have unusual properties, which are valuable for nanotechnology, electronics, optics, and other fields of materials science and technology. Owing to the material’s exceptional strength and stiffness, nanotubes have been constructed with a length-to-diameter ratio of up to 132,000,000:1 significantly larger than that for any other material) with the DNA (Deoxyribonucleic acid is a molecule composed of two chains that coil around each other to form a double helix carrying the genetic instructions used in the growth, development, functioning, and reproduction of all known living organisms and many viruses) and screening of the complex’s optical signal; (3) selection of the DNA-SWCNT (Carbon nanotubes (CNTs) are allotropes of carbon with a cylindrical nanostructure. These cylindrical carbon molecules have unusual properties, which are valuable for nanotechnology, electronics, optics, and other fields of materials science and technology. Owing to the material’s exceptional strength and stiffness, nanotubes have been constructed with a length-to-diameter ratio of up to 132,000,000:1,significantly larger than that for any other material) complexes exhibiting an improved optical signal. After several cycles of evolution, we can evolve DNA-SWCNT (Carbon nanotubes (CNTs) are allotropes of carbon with a cylindrical nanostructure. These cylindrical carbon molecules have unusual properties, which are valuable for nanotechnology, electronics, optics, and other fields of materials science and technology. Owing to the material’s exceptional strength and stiffness, nanotubes have been constructed with a length-to-diameter ratio of up to 132,000,000:1 significantly larger than that for any other material) complexes that show enhanced optical behavior. Using a directed evolution approach X’s team was able to engineer new DNA-SWCNTs (Carbon nanotubes (CNTs) are allotropes of carbon with a cylindrical nanostructure. These cylindrical carbon molecules have unusual properties, which are valuable for nanotechnology, electronics, optics, and other fields of materials science and technology. Owing to the material’s exceptional strength and stiffness, nanotubes have been constructed with a length-to-diameter ratio of up to 132,000,000:1 significantly larger than that for any other material) with optical signals that are increased by up to 56 percent — and they did it over only two evolution cycles. “The majority of researchers in this field just screen large libraries of different materials in hopes of finding one with the properties they are looking for” says X. “In optical nanosensors we try to improve properties like selectivity, brightness and sensitivity. By applying directed evolution we provide researchers with a guided approach to engineering these nanosensors”. The study shows that what is essentially a bioengineering technique can be used to more rationally tune the optoelectronic properties of certain nanomaterials. X explains: “Fields like materials science and physics are mostly preoccupied with defining material structure-function relationships making materials that lack this information difficult to engineer. But this is a problem that nature solved billions of years ago — and in recent decades biologists have tackled it as well. I think our study shows that as materials scientists and physicists we can still learn a few pragmatic lessons from biologists”.