What is bionanotechnology?

Transcription

1 In today s lecture, we will cover: What is bionanotechnology? What is bionanotechnology? Bionanotechnology is nanotechnology that uses biological starting materials, biological design principles or has biological or medical applications. How can DNA be used in nanotechnology? What are aptamers? ATP synthase Nano motor Ribosome Nano factory 1 Using ATP synthase for a rotor Ni nanopropellor attached to ATP synthase, then attached to a surface. Rotation powered by 2 mm ATP Mimicking the ATP synthase nano rotor Ricky K. Soong, et al. Powering an Inorganic Nanodevice with a Biomolecular Motor Science 290, 1555 (2000) 1

2 Molecular assembler mimicking the ribosome How can DNA be used in nanotechnology? nanomachine-mimics-natures-protein-factory/ Science 11 January 2013: Vol. 339 no pp DNA s unique properties make it wellsuited for nanotechnology Size/Shape Diameter of about 2.5 nm Helical pitch of 3.4 nm (10 base pairs) Persistence length of 50 nm DNA s unique properties make it wellsuited for nanotechnology Recognition A binds to T G binds to C Shape of DNA is programmable and predictable 2

3 DNA s unique properties make it wellsuited for nanotechnology DNA nanoscaffolds Can be chemically synthesized PCR to make many copies DNA nanomachines DNA nanosensors DNA as a nanoscaffold One approach uses sticky ends and DNA tiles DNA as a nanoscaffold Very complicated tiles can make interesting patterns Seeman et al Nature 1991, 350, 631 Seeman JACS, 2004, 126,

4 How can this be useful? Can use the DNA patterns as a scaffold or a template for other nanocomponents How can this be useful? Can use the DNA patterns as a scaffold or a template for other nanocomponents Nano Lett Vol. 6, No. 7, Nano Lett Vol. 6, No. 7, DNA can access complex patterns A newer approach is called DNA origami A long piece of viral DNA is folded by a computer program into a certain pattern Short staple DNA are designed to hold the folds in place Sharma et al Science

5 DNA Origami can make complex patterns DNA Origami can make complex 2D and 3D patterns Rothemund, P.W.K. Nature 2006, 440, Rothemund, P.W.K. Nature 2006, 440, D box made with DNA origami You can make your own! dna origami.org/ AFM images of the sheets (a), the folded box (b), and the box with the lid open (c). Andersen et al. Self-assembly of a nanoscale DNA box with a controllable lid Nature 2009, 459,

6 DNA as a nanomachine A DNA based molecular assembler We are probably years away from DNA machines that can do complex tasks Current nanomachines are very simple Seeman, A proximity based programmable DNA nanoscale assembly line Nature Volume: 465, Pages: A DNA based molecular assembler UV powered DNA walker UV light excites a molecule to release an electron Electron reacts and breaks DNA DNA releases and walks along a track Seeman, A proximity-based programmable DNA nanoscale assembly line Nature Volume: 465, Pages:

7 UV powered DNA walker UV light excites a molecule to release an electron Electron reacts and breaks DNA DNA releases and walks along a track DNA as a nanosensor (cont d) DNA recognition is not limited to its complementary sequence Certain type of DNA can also recognize and bind to other molecules These molecules are known as Aptamers Aptus: to fit What are Aptamers? Aptamers are synthetic stretches of DNA or RNA that can fold into nanosized shapes capable of binding to molecular targets bind targets (small molecules, proteins) with high affinity K d values in the micromolar to subnanomolar range What are Aptamers? Aptamers are synthetic stretches of DNA or RNA that can fold into nanosized shapes capable of binding to molecular targets remarkable selectivity Theophyline aptamer: difference of a single methyl group leads to times weaker binding 7

8 Aptamers are discovered by the SELEX screening procedure SELEX explained: Science Magazine s Dance your Ph.D Random region Fixed regions Clone, sequence, characterize PCR target Tuerk, C., Gold, L. Science 1990; Ellington, A.D., Szostak, J.W. Nature 1990 Can aptamers make fertilizers smart? You cannot feed 6B people today (2007) and 9B in 2050 without judicious use of chemical fertilizers." Dr. Jacques Diouf, Director General of the FAO. The efficiency of current fertilizer technology is very low 50 70% of fertilizer applied to crops is lost to air, water and other processes >$1B a year for Canadian farmers Major environmental impact (runoff and greenhouse gas emissions) 8

9 Can aptamers make fertilizers smart? Preparation of hollow capsules with aptamer loaded walls Y. Sultan and M. C. DeRosa Small 2011, 7, Preparation of hollow capsules with aptamer loaded walls Aptamer capsules specific for a root exudate show increased dye permeability Film deposition by Layer by Layer approach on sacrificial templates Target molecule Diffusion coefficient (µm 2 /s) Aptamer film with Exudate 0.113± Aptamer film with Negative 0.051± control Y. Sultan and M. C. DeRosa Small 2011, 7, Sultan and DeRosa 9