Light-emitting diodes (LEDs) are considered as the most promising candidate for the next-generation lighting. They are also widely used as backlight units (BLU) for displays and light sources for various other applications. To extend the range of applications of the LEDs, the improvement of the LED performance is required. Since LEDs are optoelectronics devices that convert the electrical power into the optical power, the understanding of how photons generated in LEDs behave is most important. In this paper, we have investigated the optical processes in InGaN-based LEDs using electroreflectance (ER) and photocurrent (PC) spectroscopies. We have chosen some factors that affects the optical transition in LEDs and performed the ER and PC spectroscopies by changing those factors.

The extracellular matrix provides both chemical and physical cues that control cellular processes such as migration, division, differentiation, and cancer progression. Cells can mechanically alter the matrix by applying forces that result in matrix displacements, which in turn may localize to form dense bands along which cells may migrate. To quantify the displacements, we use confocal microscopy and fluorescent labeling to acquire high-contrast images of the fibrous material. Using a technique for quantitative image analysis called digital volume correlation, we then compute the matrix displacements. Our experimental technology offers a means to quantify matrix mechanics and cell-matrix interactions. We are now using these experimental tools to modulate mechanical properties of the matrix to study cell contraction and migration.

We report an aptasensor for homogeneous ochratoxin A (OTA) detection based on luminescence resonance energy transfer (LRET). This system uses upconversion nanoparticles (UCNPs), such as NaYF₄:Yb³⁺, Er ³⁺, as the donor. The aptamer includes the optimum-length linker (5-mer-length DNA) and OTA-specific aptamer sequences. Black hole quencher 1 (BHQ1), as the acceptor, was modified at the 3' end of the aptamer sequence. BHQ1 plays as a quencher in LRET aptasensor and shows absorption at 543 nm, which overlaps with well the emission of the UCNPs. When OTA is added, the BHQ1-labeled OTA aptamer was folded due to the formation of the G-quadruplex-OTA complex, which induced the BHQ1 close to the UCNPs. Consequently, resonance energy transfer between UCNPs (donor) and BHQ1 (acceptor) enables quenching of upconversion luminescence signals under laser irradiation of 980 nm. Our results showed that the LRET-based aptasensor allows specific OTA analysis with a limit of detection of 0.03 ng/mL. These results demonstrated that the OTA in diverse foods can be detected specifically and sensitively in a homogeneous manner.

Monitoring blood glucose level of diabetic patients is crucial in diabetes care from life threating complications. Selfmonitoring blood glucose (SMBG) that involves finger prick to draw blood samples into the measurement system is a widely-used method of routine measurement of blood glucose levels to date. SMBG includes, however, unavoidable pain problems resulting from the repetitive measurements. We hereby present a hydrogel-based electrochemical (H-EC) sensor to monitor the glucose level, non-invasively. Glucose oxidase (GOx) was immobilized in the disc-type hydroxyethyl methacrylate (HEMA) based hydrogel and kept intact in the hydrogel. Fast electron transfer mediated by Prussian blue (PB, hexacyanoferrate) generated efficient signal amplifications to facilitate the detection of the extracted glucose from the interstitial fluid. The linear response and the selectivity against glucose of the H-EC sensor were validated by chronoamperometry. For the practical use, the outcomes from the correlation of the extracted glucose concentration and the blood glucose value by on-body extraction, as well as the validation of the hydrogel-based electrochemical (H-EC) device, were applied to the on-body glucose monitoring.

Surface plasmon resonance (SPR) has been heavily used as biosensors and studied dominantly on a flat surface. Recently, flexible sensor platforms have emerged, for example, as wearable devices. Here, we report investigation of SPR characteristics on a curved film structure. A rigorous 3D computational model requires extremely heavy calculation time and resources. Therefore, we adopted segmentation analysis in which curved surface is divided into an array of flat segments. Such analysis allows fast and efficient calculation. The results indicate that increased curvature produces broader SPR due to wider momentum-matching. The segmentation analysis is expected to play a critical role for diverse optical elements on curved surface.

Plasmonic optical trapping allows trapping and manipulation of micro- and even nanometer-sized particles using localized and enhanced electric fields by plasmon resonance in metallic nanostructure. We consider an optical conveyor belt consisting of an array of nanodisks acting as optical tweezers with different sizes to implement a system to trap and manipulate particles through a laser-induced gradient force. An electric field induced and localized at each optical resonator is sensitive to the wavelength and polarization. The maximum electric field is enhanced at resonant wavelength depending on the shape and size of the plasmonic nanostructure used for light localization. By changing the light wavelength and polarization, the position of localized light induced in the disk can be determined and nanoparticles can be moved to a desired location through the variation of resonance conditions without any mechanical forces.

Nanoscale imaging techniques that can be used to visualize and characterize local aggregations of the embedded nanoparticulates with sufficient resolution have attracted a great deal of interest. Ultrasonic scanning probe microscopy (SPM) and its derivatives are nondestructive techniques that can be used to elucidate subsurface nanoscale features and mechanical properties. Although many different ultrasonic methods have been used for subsurface imaging, the mechanisms and crucial parameters associated with the contrast formation in subsurface imaging are still unclear. Here, the impact of mechanical properties of the nanoparticulates/matrix, size of the nanoparticulates, buried depth of the nanoparticulates, and the ultrasonic excitation frequency on the developed ultrasonic SPM images have been investigated. To verify our theoretical model, experimental measurements of scanning near-field ultrasound holography (SNFUH) have been recreated in our theoretical analysis to reveal comparable variations in phase contrast measured in SNFUH while scanning over the nanoparticulates embedded in bacteria.

To overcome the speed limitation in Raman imaging, we have developed a microscope system that detects Raman spectra from hundreds of points in a sample simultaneously. The sample was illuminated by a line-shaped focus, and Raman scattering from the illuminated positions was measured simultaneously by an imaging spectrophotometer. We applied the line-illumination technique to observe the dynamics of intracellular molecules during cellular events. We found that intracellular cytochrome c can be clearly imaged by resonant Raman scattering. We demonstrated label-free imaging of redistribution of cytochrome c during apoptosis and osteoblastic mineralization. We also proposed alkyne-tagged Raman imaging to observe small molecules in living cells. Due to its small size and the unique Raman band, alkyne can tag molecules without strong perturbation to molecular functions and with the capability to be detected separately from endogenous molecules.

The FREND System is a portable cartridge reader, quantifying analytes by measuring laser-induced fluorescence in a single-use reagent cartridge. The objective of this study was to evaluate FREND-SAA and FREND-Hp assays. The FREND-SAA and Hp assays were standardized to the WHO and IFCC reference materials. Analytical performance studies of Precision, Linearity, Limits of Detections, Interferences, and Method Comparisons for both assays were performed according to the CLSI guidelines. Both assays demonstrated acceptable imprecision of %CV in three different levels of samples. The linearity of the assays was found to be acceptable (SAA 5~150 mg/L, Hp 30~400 mg/dL). The detection limits were 3.8 mg/L (SAA) and 10.2 mg/dL (Hp). No significant interference and no significant deviation from linearity was found in the both comparison studies. In conclusion, NanoEnTek’s FREND-SAA and Hp assays represent rapid, accurate and convenient means to quantify SAA and Hp in human serum on FREND system.

Unlike those of other ordinary laser scanning microscopies in the past, nonlinear optical laser scanning microscopy (SHG, THG microscopy) applied ultrafast laser technology which has high peak powers with relatively inexpensive, low-average-power. It short pulse nature reduces the ionization damage in organic molecules. And it enables us to take bright label-free images. In this study, we measured cell division of zebrafish egg with ultrafast video images using multimodal nonlinear optical microscope. The result shows in-vivo cell division label-free imaging with sub-cellular resolution.

Nonlinear optical microscopy has enabled the possibility to explore inside the living organisms. It utilizes ultrashort laser pulse with long wavelength (greater than 800nm). Ultrashort pulse produces high peak power to induce nonlinear optical phenomenon such as two-photon excitation fluorescence (TPEF) and harmonic generations in the medium while maintaining relatively low average energy pre area. In plant developmental biology, confocal microscopy is widely used in plant cell imaging after the development of biological fluorescence labels in mid-1990s. However, fluorescence labeling itself affects the sample and the sample deviates from intact condition especially when labelling the entire cell. In this work, we report the dynamic images of Arabidopsis thaliana root cells. This demonstrates the multimodal nonlinear optical microscopy is an effective tool for long-term plant cell imaging.

We have successfully fabricated nanocomposite, which is composed of polyaniline (PAni) and pyrene butyric acid (Pyba) via solvent shift method, and the outer layer was enclosed by Tween 80 as a surfactant. First of all, the various ratios between PAni and Pyba were applied for synthesis of polyaniline nanocomposite, and an identical condition for exhibition of proper absorbance and fluorescence properties was found out. The morphology of polyaniline nanocomposite was confirmed via scanning electron microscopic imaging and hydrodynamic size was also confirmed by dynamic light scattering method. We demonstrated that confined self-doped polyaniline nanocomposite as a pH sensing agent are preserved in the doped state even at a neutral pH value. Especially, PAni exhibited strong convertible property at absorbance spectra, on the other hand, Pyba showed changing property at fluorescence spectra at various pH values. In conclude, this polyaniline nanocomposite can accomplish as a fine nanoagent expressing absorbance and fluorescence properties according to surrounding pH values.

In this study, C-reactive protein (CRP) was detected by monitoring of LSPR shift promoted by precipitation of 4-chloro-1-naphthol (4-CN). The precipitation occurred by horseradish peroxide (HRP) catalyst which is modified at CRP-detection antibody utilized in sandwich enzyme-linked immunosorbent assay (ELISA) on gold nano bipyramid (GNBP) substrate. Due to 4-CN precipitates which are located nearby the surface of GNBP, local refractive index (RI) and molecular density were greatly increased. This phenomenon eventually induced strong spectral red-shift of absorption band of GNBP. An excellent linear relationship (R²=0.9895) between the LSPR shift and CRP concentration was obtained in the range from 100 pg/mL to 100 ng/mL and limit of detection (LOD) was reached to 87 pg/mL.

In this paper, we introduce a wellness software platform, called WellnessHumanCare, is a semi-automatic wellness management software platform which has the functions of complex wellness data acquisition(mental, physical and environmental one) with smart wearable devices, complex wellness condition analysis, private-aware online/offline recommendation, real-time monitoring apps (Smartphone-based, Web-based) and so on and we has demonstrated a wellness management service with 79 participants (experimental group: 39, control group: 40) who has worked at experimental group (H Corp.) and control group (K Corp.), Korea and 3 months in order to show the efficiency of the WellnessHumanCare.

It is known that naphthalene diimide carrying two substituents binds to DNA duplex with threading intercalation. Naphthalene diimide carrying ferrocene moieties, ferrocenylnaphthalene diimide (FND), formed a stable complex with DNA duplex and an electrochemical gene detection was achieved with current signal generated from FND bound to the DNA duplex between target DNA and DNA probe immobilized electrode. FND couldn’t bind to the mismatched and its surrounding region of DNA duplex and thus FND was applied to the precision detection of single nucleotide polymorphisms (SNPs) using the improved discrimination ability between fully matched and mismatched DNA hybrids and multi-electrode chip. Some of FND derivatives bound to telomere DNA tetraplex stronger than to DNA duplex and was applied to cancer diagnosis as a measure of the elongated telomere DNA with telomerase as a suitable maker of cancer. Furthermore, cyclic naphthalene diimides realized the extremely high preference for DNA tetraplex over DNA duplex. Such molecules will open an effective anti-cancer drug based on telomerase specific inhibitor.