Glucose-Responsive Charge-Switchable Lipid Nanoparticles for Insulin Delivery.

Lipid nanoparticle-based drug delivery systems have a profound clinical impact on nucleic acid-based therapy and vaccination. Recombinant human insulin, a negatively-charged biomolecule like mRNA, may also be delivered by rationally-designed positively-charged lipid nanoparticles with glucose-sensing elements and be released in a glucose-responsive manner. Herein, we have designed phenylboronic acid-based quaternary amine-type cationic lipids that can self-assemble into spherical lipid nanoparticles in an aqueous solution. Upon mixing insulin and the lipid nanoparticles, a heterostructured insulin complex is formed immediately arising from the electrostatic attraction. In a hyperglycemia-relevant glucose solution, lipid nanoparticles become less positively charged over time, leading to reduced attraction and subsequent insulin release. Compared with native insulin, this lipid nanoparticle-based glucose-responsive insulin shows prolonged blood glucose regulation ability and blood glucose-triggered insulin release in a type 1 diabetic mouse model.

Efficient and broadband wavelength conversion in a slot waveguide with the periodic structure altering the phase-mismatch.

High-efficiency wavelength conversion based on the quasi-phase-matching technique is proposed and simulated in a silicon slot waveguide. Due to the tight light confinement and high nonlinear material (silicon nanocrystal) filled in the slot region, a large nonlinear coefficient of 4100/(W·m) is achieved. With the waveguide width changing alternately to manage the phase-mismatch, periodical attenuation of the idler power is suppressed even in the presence of severe dispersion. Numerical simulation shows that an efficiency of -12.3 dB at 1850 nm and a 3-dB bandwidth of 484 nm are available for the 1550 nm wavelength pump in a 4 mm long silicon slot waveguide.

All-optical logic operation of polarized light signals in highly nonlinear silicon hybrid plasmonic microring resonators.

All-optical logic operation is theoretically demonstrated by means of polarization-dependent four-wave mixing (FWM) processes in a highly nonlinear silicon hybrid plasmonic waveguide (HPWG) microring resonator. We design an ultra-compact (radii = 1 µm) microring resonator (MRR) that is realized by using a silicon HPWG with the capacity for subwavelength-bending. The HPWG exhibits very high confinement (Aeff~0.045 µm(2)) that can result in a remarkably high nonlinear parameter (γ~3000 W(-1) m(-1)), given a highly nonlinear gap material. By manipulating the polarization properties of the pump and signals with a very low electric field (|E|~10(8) Vm(-1)), all-optical NOT, NOR, and NAND logical operations are obtained through the FWM process. These compact all-optical nanoplasmonic devices are stable, fabrication simplified, and silicon on insulator (SOI) compatible.

Broadband and transparent wavelength conversion based on dispersion-flattened double-slot waveguide.

The flat and low second-order dispersion of 0∼-13 ps2/km in a double-slot waveguide is optimized for broadband wavelength conversion. Subsequently, a 3 dB conversion bandwidth of about 1200 nm is presented by four-wave mixing based on the above structure in simulation. Attributed to the small phase mismatch caused by low second- and fourth-order dispersion parameter in a large waveband, the 3 dB conversion bandwidth is almost constant at about 1200 nm with the pump wavelength varying from 2200 to 2800 nm. The results indicate that this dispersion-flattened double-slot waveguide is not only an ideal device for broadband wavelength conversion but also can realize the transparency of pump wavelength, which has potential applications in wavelength conversion.

Quasi-phase-matched four-wave mixing generation between C-band and mid-infrared regions using a symmetric hybrid plasmonic waveguide grating.

A symmetric hybrid plasmonic waveguide (SHPW) configuration based on quasi-phase-matched (QPM) four-wave mixing (FWM) is proposed to realize efficient FWM conversion between the C-band and mid-infrared (mid-IR) regions. Due to the ability to allow strong confinement of light, an extremely large nonlinear parameter γ>104 m-1 W-1 and a very low propagation loss ∼3×10-3 dB/µm accompanying the sub-λ scale (effective mode area Aeff∼3×10-2 µm2) are achieved by optimally designing the SHPW geometrical parameters. In addition, a QPM technique is adopted to achieve a relatively long effective length of FWM nonlinear process by constructing a long SHPW grating, thereby resulting in highly efficient wavelength conversion without rigorous dispersion engineering of waveguide structures. By using numerical simulations we have demonstrated that, for a pump wavelength of 1,800 nm, an efficient and flat FWM conversion of ∼-17 dB (∼-22 dB) could be realized around a target signal wavelength of the C-band: 1,530-1,565 nm (mid-IR: 2,118-2,180 nm), in a 1,000 µm-long grating with a serious phase mismatch.

Multiwavelength generation based on a mode-locked fiber laser using carbon nanotube and fiber Fabry-Perot filter.

In this paper, a novel and compact configuration of stable multiwavelength generation with a uniform wavelength interval is proposed for the first time to our knowledge. It employs a mode-locked fiber laser using a carbon nanotube and spectrum-slicing technique. A flat rectangular optical output spectrum is demonstrated by adjusting the dispersion value of the fiber-loop cavity and the pump power. With a fiber Fabry-Perot filter, 33 wavelengths with 0.2 nm spacing are obtained among the power uniformity of 2.3 dB. Moreover, the variations of output power at each wavelength are all less than 0.1 dB, which implies excellent stability of the whole structure.

Effect of Grafting Conditions on the Interfacial Properties of Silane Modified Wood Veneer/PE Film Plywood.

In order to elucidate the importance of grafting in the compatibilization process of silane coupling agents, poplar veneer was treated with silane coupling agents and grafted under different heating conditions. The treated veneers were used composited with PE film to prepare different plywood samples. XPS and WCA were used to analyze the effect of grafting conditions on the surface properties of the silane-treated veneer. The results showed that free silanols can physically be adsorbed onto all silane-treated veneer surfaces, forming hydrogen-Si-O-Si- bonds and therefore increasing the water contact angle. Only under heating conditions could the -Si-O-Si- be converted into covalent -Si-O-C- bonds, which helped to improve the bonding strength. When silane-treated veneer was grafted at 120 °C for 90 min, the tensile shear strength of plywood reached 1.03 MPa, meeting the requirements of GB/T 9846.3-2004 for outdoor materials. Enhanced interlock between silane-modified veneer and PE film was observed under the optimal grafting condition by SEM. The better interface structure allowed improvement of thermal stability. DMA results showed that the retention rate in storage modulus at 130 °C was 60% for the grafted sample, while the retention rate for the ungrafted sample was only 31%.