Live cell near-field optical imaging and voltage sensing with ultrasensitive force control.

Force controlled optical imaging of membranes of living cells is demonstrated. Such imaging has been extended to image membrane potential changes to demonstrate that live cell imaging has been achieved. To accomplish this advance, limitations inherent in atomic force microscopy (AFM) since its inception in 1986 [G. Binnig, C. F. Quate, and C. Gerber, "Atomic Force Microscope," Phys. Rev. Lett. 56, 930-933 (1986).] had to be overcome. The advances allow for live cell imaging of a whole genre of functional biological imaging with stiff (1-10N/m) scanned probe imaging cantilevers. Even topographic imaging of fine cell protrusions, such as microvilli, has been accomplished with such cantilevers. Similar topographic imaging has only recently been demonstrated with the standard soft (0.05N/m) cantilevers that are generally required for live cell imaging. The progress reported here demonstrates both ultrasensitive AFM (~100pN), capable of topographic imaging of even microvilli protruding from cell membranes and new functional applications that should have a significant impact on optical and other approaches in biological imaging of living systems and ultrasoft materials.

Wireless Communication with Nanoplasmonic Data Carriers: Macroscale Propagation of Nanophotonic Plasmon Polaritons Probed by Near-Field Nanoimaging.

The ability to control the energy flow of light at the nanoscale is fundamental to modern communication and big-data technologies, as well as quantum information processing schemes. However, since photons are diffraction-limited, efforts of confining them to dimensions of integrated electronics have so far proven elusive. A promising way to facilitate nanoscale manipulation of light is through plasmon polaritons-coupled excitations of photons and charge carriers. These tightly confined hybrid waves can facilitate compression of optical functionalities to the nanoscale but suffer from huge propagation losses that limit their use to mostly subwavelength scale applications. With only weak evidence of macroscale plasmon polaritons, propagation has recently been reported theoretically and indirectly, no experiments so far have directly resolved long-range propagating optical plasmons in real space. Here, we launch and detect nanoscale optical signals, for record distances in a wireless link based on novel plasmonic nanotransceivers. We use a combination of scanning probe microscopies to provide high resolution real space images of the optical near fields and investigate their long-range propagation principles. We design our nanotransceivers based on a high-performance nanoantenna, Plantenna, hybridized with channel plasmon waveguides with a cross-section of 20 nm × 20 nm, and observe propagation for distances up to 1000 times greater than the plasmon wavelength. We experimentally show that our approach hugely outperforms both waveguide and wireless nanophotonic links. This successful alliance between Plantenna and plasmon waveguides paves the way for new generations of optical interconnects and expedites long-range interaction between quantum emitters and photomolecular devices.

Direct antifungal effect of femtosecond laser on Trichophyton rubrum onychomycosis.

Onychomycosis is caused by dermatophyte infection of the nail. Though laser energy has been shown to eliminate dermatophytes in vitro, direct laser elimination of onychomycosis is not successful due to difficulties in selectively delivering laser energy to the deeper levels of the nail plate without collateral damage. Femtosecond (fsec) infrared titanium sapphire lasers circumvent this problem by the nonlinear interactions of these lasers with biological media. This quality, combined with the deeply penetrating nature of the near-infrared radiation, allows elimination of deeply seeded nail dermatopytes without associated collateral damage. Nail cuttings obtained from patients with onychomycosis caused by Trichophyton rubrum underwent fsec laser irradiation using increasing laser intensities with the focus scanned throughout the whole thickness of the nail specimen. The efficacy of the laser treatment was evaluated by subculture. Scanning electron microscopy was used to determine fsec laser-induced collateral damage. We found that a fsec laser fluence of 7 x 10(31) photons m(-2) s(-1) or above successfully inhibited the growth of the fungus in all samples examined, whereas laser intensities above 1.7 x 10(32) photons m(-2) s(-1) affected the structure of the nail plate. Our findings suggest that T. rubrum-mediated onychomycosis may be treated by fsec laser technology.

D-glucose-induced second harmonic generation response in human erythrocytes.

The first experimental results of the nonresonant second harmonic generation (SHG) studies of human erythrocytes membrane exposed to various glucose concentrations in phosphate buffered saline (PBS solution) are presented in this article. It is shown that the SHG signal from the membrane can be altered as a function of glucose concentration. The link between the variation of the SHG intensity and the membrane dielectric permittivity with glucose is established both theoretically and experimentally by comparison with time domain dielectric spectroscopy (TDDS) measurement data.