Near-infrared nanosecond-pulsed laser-activated highly efficient intracellular delivery mediated by nano-corrugated mushroom-shaped gold-coated polystyrene nanoparticles.

Here, an efficient intracellular delivery of molecules with high cell viability is reported using nanosecond-pulsed laser-activated plasmonic photoporation, mediated by high-aspect-ratio nano-corrugated mushroom-shaped gold-coated polystyrene nanoparticles (nm-AuPNPs) at near-infrared wavelength. Upon pulsed laser illumination, nm-AuPNPs exhibit greater plasmonic extinction than spherical AuPNPs, which increase their energy efficiency and reduce the necessary illumination of light, effectively controlling cell damage and improving the delivery efficiency. Nm-AuPNPs exhibit surface plasmon absorption at near infrared region with a peak at 945 nm. Pulsed laser illumination at this plasmon peak triggers explosive nanobubbles, which create transient membrane pores, allowing the delivery of dyes, quantum dots and plasmids into the different cell types. The results can be tuned by laser fluence, exposure time, molecular size and concentration of nm-AuPNPs. The best results are found for CL1-0 cells, which yielded a 94% intracellular PI dye uptake and ∼100% cell viability at 35 mJ cm-2 laser fluence for 945 nm wavelength. Thus, the presented approach has proven to have an inevitable potential for biological cell research and therapeutic applications.

Application of strong transverse magneto-optical Kerr effect on high sensitive surface plasmon grating sensors.

A high sensitive sensor is demonstrated by exploiting strong transverse magneto-optical Kerr effect on a ferromagnetic surface plasmon grating. The surface plasmon grating, made of a hybridized Au/Fe/Au layer, exhibits a very dispersive Kerr parameter variation near the surface plasmon polariton (SPP) wavelength via coherent scattering of the SPP on the grating structure. Interrogating this Kerr parameter can be utilized for detecting chemical or biological objects in a fluid medium. The experiment results show the minimal detectable mass concentration of sodium chloride in a saline solution is 4.27 × 10(-3) %, corresponding to a refractive index change of 7.60 × 10(-6) RIU. For an avidin-biotin interaction experiment, the sensitivity of avidin detection in PBS solution is 1.97 nM, which is limited by the index fluctuation of flowing media during measurement.

Manipulation of micro-particles through optical interference patterns generated by integrated photonic devices.

Micro-particle transport and switch governed by guided-wave optical interference are presented. The optical interference, occurring in a directional coupler and a multi-mode interferometer made by inverted rib waveguides, results in a specific evanescent field dependent on wavelength. Through a detailed theoretical analysis, the field of induced optical force shows a correlative pattern associated with the evanescent field. Experimental results demonstrate that 10 µm polystyrene beads are propelled with a trajectory subject to the interference pattern accordingly. By launching different wavelengths, the polystyrene beads can be delivered to different output waveguide ports. Massive micro-particle manipulation is applicable.

Study of disklike microdroplet cavities directly coupled to liquid-core waveguides.

A design of microfluidic devices is presented to integrate single-mode, liquid-core waveguides with microfluidic channels that generate and deliver disklike emulsion microdroplet cavities doped with an organic dye. The microcavity modes can be directly coupled to the liquid waveguide. Cavity-enhanced spontaneous emission was observed at the waveguide with low pump pulse energy.

Direct patterning of zinc oxide with control of reflected color through nano-oxidation using an atomic force microscope.

Atomic force microscope oxidation on Zn creating amorphous ZnO (a-ZnO) with the a-ZnO showing multiple colors under white light at different oxidation voltages was successfully demonstrated. Simulation of reflected colors at different thicknesses of a-ZnO was also conducted. The presented technique can not only be applied to near diffraction limit multilevel optical data storage, but also makes it possible to represent the color spectra observed in nature at near diffraction limits. It can also be used for device fabrication in situations exploiting the semiconductor nature of ZnO.