APPLICATIONS : NANOPHOTONICS AND BIO-MEDICAL ENGINEERING Lee Woo Ram Electro-medical Fusion Engineering lab Seoul National University

Contents Plasmonics - Optical tweezing : Low-power nano-optical vortex trapping via plasmonic diabolo nanoantennas - Building plasmonic nanostructures with DNA - Discriminating chiral biomolecules - Nanowire-based single-cell endoscopy Photonic crystal - Biosensors : highly sensitive biochemical detection Metamaterial - Terahertz Technology : A new era of medical imaging

OPTICAL TWEEZING

A Basic Principle : Radiation Pressure Limitations Trapped particles are susceptible to optical damage by absorptive heating. Multiple particles may be attracted. The trapping of low-index particles requires different beam profile.

And another limitation!! For small particle…… Brownian motion makes problem... The magnitude of the restoring force decreases abruptly, which results in a shallower trapping well The damping of trapped specimen decreases because of a reduction in viscous drag Plasmonic nanostructure can be engineered to efficiently couple to concentrate light into highly localized and intense optical fields known as hot spot!

Surface Plasmon-based Microtrapping

Plasmonic Antennas Although gold pads measuring around 100nm can be designed to be resonant in the near-infrared region of the spectrum, they are not suited for trapping because of their limited intensity and symmetry in the optical near field Much higher control of plasmonic fields can be achieved through an alternative technique that exploits the strong electromagnetic coupling between several adjacent plasmonic nanostructures Among the most interesting geometries, plasmonic antennas have received much attention for their ablity to concentrate propagating light well beyond the diffraction limit Down-scaling the pad diameter……..

Subwavelength trapping with plasmonic antennas

Diabolo nanoantenna for nano-optical vortex trapping

Building plasmonic nanostructures with DNA

Schematic of Plasmonic Nanostructures with DNA

Why DNA for plasmonic? The reason of difficulties in controlling nanoparticle Interactions between nanoparticles are very complex and involve various temporal and spatial forces Most nanoparticles do not self-assemble into their thremodynamically lowest energy states, but rather form kinetically trapped non-equilibrium structures Nanoparticle Corona Engineering!! And DNA is an outstanding material for nanoparticle corona engineering The reason is.. Specific Watson-Crick base pairing provides controllable degrees of hydrogen bonding that enable the adhesive forces between DNA coronae to be systematically and precisely programmed. DNA nanotechnology uses the unique molecular recognition properties of DNA and other nucleic acids to create self assembling branched DNA complexes with useful properties

For example, DNA chip

Monofunctionalization Attaching a Single DNA strand to a single plasmonic nanoparticle at a one-to-x Control over DNA-mediated assembly of complex inorganic nanostructures depend crucially upon the ability to isolate discrete DNA-nanoparticle building blocks in which the number of DNA strand is controlled

HPLC[High performance liquid chromatography]

Building plasmonic molecules with DNA

Building plasmonic nanostructures with DNA

Discriminating chiral biomolecules

What is Chiral biomolecules? A chiral molecule have the same chemical and physical properties with structural techniques. For example, their nuclear magnetic resonance and infrared spectra are identical.

Fortunately….. Both enantiomers interact with polarized light in different ways: in particular, there are small differences in the amount of left- and right- hand circularly polarized light they absorb. However, this effect which is known as circular dichroism is very week, so detection methods based on it have low sensitivity To increase the interaction of the light with the molecules by attaching a fluorophore or a metallic nanoparticle that supports a localized surface- plasmon resonance.

PCM(planar chiral metamaterials)

Nanowire-based single-cell endoscopy

Cell Endoscopy? Why? Do you think that you can see this picture when you just look at the living cell through microscopy lens?

Cell Observation Process

Other method

How about Cell Endoscopy?

Quantum Dot Delivery Service~

Subcellular imaging with nanowire endoscopes in a single living cell

Local sensing of pH by the nanowire endoscope

Photonic Crystal biosensor

Colorimetric resonant optical biosensors

Imaging method for detection of cancer cell cytotoxicity and proliferation

Photonic Crystal Waveguide biosensor

Experiment

Terahertz Technology

Thank You