Expansion microscopy (ExM) enables imaging of preserved specimens with nanoscale precision on diffraction limited instead of specialized super-resolution microscopes. ExM works by physically separating fluorescent probes after anchoring them to a swellable gel. The first expansion microscopy method was unable to retain native proteins in the gel and used custom made reagents not widely available. Here, we describe protein retention ExM (proExM), a variant of ExM that anchors proteins to the swellable gel allowing the use of conventional fluorescently labeled antibodies and streptavidin, and fluorescent proteins. We validate and demonstrate utility of proExM for multi-color super-resolution (~70 nm) imaging of cells and mammalian tissues on conventional microscopes.

The fabrication process and performance characteristics of the laser lift-off ͑LLO͒ GaN light-emitting diodes ͑LEDs͒ were investigated. The LLO-GaN LEDs were fabricated by lifting off the GaN LED wafer structure grown on the original sapphire substrate by a KrF excimer laser at 248 nm wavelength with the laser fluence of 0.6 J/cm 2 and transferring it onto a Cu substrate. The LLO-GaN LEDs on Cu show a nearly four-fold increase in the light output power over the regular LLO-LEDs on the sapphire substrate. High operation current up to 400 mA for the LLO-LEDs on Cu was also demonstrated. Based on the emission wavelength shift with the operating current data, the LLO-LEDs on Cu show an estimated improvement of heat dissipation capacities by nearly four times over the light-emitting devices on sapphire substrate. The LLO process should be applicable to other GaN-based LEDs in particular for those high light output power and high operation current devices.

Expansion microscopy (ExM) physically magnifies biological specimens to enable nanoscaleresolution imaging on conventional microscopes. Current ExM methods permeate biological specimens with free radical-polymerized polyacrylate hydrogels, whose network structure limits the microscopy resolution enabled by ExM. Here we report that ExM is possible using hydrogels with more homogeneous network structure, assembled via non-radical terminal linking of monomers of tetrahedral shape. As with earlier forms of ExM, such "tetra-gel"-embedded specimens can be iteratively expanded for greater physical magnification. Iterative tetra-gel expansion of herpes simplex virus type 1 (HSV-1) virions by ~10x in linear dimension results in a viral envelope deviation from sphericity of 9.2 nm, rather than the 14.3 nm enabled by free radical-polymerized hydrogels used in earlier versions of ExM. Thus, tetra-gel polymer chemistry may support new forms of ExM imaging that introduce fewer spatial errors than earlier versions, and raise the question of whether single biomolecule precision may be achievable..

We report the fabrication of InGaN/GaN nanorod light-emitting diodes (LEDs) using inductively coupled plasma reactive-ion etching (ICP-RIE) and a photo-enhanced chemical (PEC) wet oxidation process via self-assembled Ni nanomasks. An enhancement by a factor of six times in photoluminescence (PL) intensities of nanorods made with the PEC process was achieved in comparison to that of the as-grown structure. The peak wavelength observed from PL measurement showed a blue shift of 3.8 nm for the nanorods made without the PEC oxidation process and 8.6 nm for the nanorods made with the PEC oxidation process from that of the as-grown LED sample. In addition, we have demonstrated electrically pumped nanorod LEDs with the electroluminescence spectrum showing more efficiency and a 10.5 nm blue-shifted peak with respect to the as-grown LED sample.