Demonstration of an ultrasensitive refractive-index plasmonic sensor by enabling its quadrupole resonance in phase interrogation.

We present an ultrasensitive plasmonic sensing system by introducing a nanostructured X-shaped plasmonic sensor (XPS) and measuring its localized optical properties in phase interrogation. Our tailored XPS exhibits two major resonant modes of a low-order dipole and a high-order quadrupole, between which the quadrupole resonance allows an ultrahigh sensitivity, due to its higher quality factor. Furthermore, we design an in-house common-path phase-interrogation system, in contrast to conventional wavelength-interrogation methods, to achieve greater sensing capability.

Raman spectroscopy for grading of live osteosarcoma cells.

Introduction: Osteosarcoma is the most common primary malignant bone tumor, and the grading of osteosarcoma cells relies on traditional histopathology and molecular biology methods, which require RNA extraction, protein isolation and immunohistological staining. All these methods require cell isolation, lysis or fixation, which is time-consuming and requires certain amount of tumor specimen. In this study, we report the use of Raman spectroscopy for grading of malignant osteosarcoma cells.

The activation of directional stem cell motility by green light-emitting diode irradiation.

Light-emitting diode (LED) irradiation is potentially a photostimulator to manipulate cell behavior by opsin-triggered phototransduction and thermal energy supply in living cells. Directional stem cell motility is critical for the efficiency and specificity of stem cells in tissue repair. We explored that green LED (530 nm) irradiation directed the human orbital fat stem cells (OFSCs) to migrate away from the LED light source through activation of extracellular signal-regulated kinases (ERK)/MAP kinase/p38 signaling pathway.

Regulation of the fate of human mesenchymal stem cells by mechanical and stereo-topographical cues provided by silicon nanowires.

Extracellular stimuli imposed on stem cells enable efficient initiation of mechanotransductive signaling to regulate stem cell fates; however, how such physical cues conferred by the stereo-topographical matrix govern the fate of stem cells still remains unknown. The purpose of this study is to delineate the effects of stereotopography and its various relevant physical properties on the fate regulation of human mesenchymal stem cells (hMSCs). Stereo-topographical silicon nanowires (SiNWs) that were precisely controlled with respect to their various dimensions and their growth orientation were used in this study.

Study of optical phase transduction on localized surface plasmon resonance for ultrasensitive detection.

Localized surface plasmon resonance (LSPR) has shown its remarkable applications in biosensing, bioimaging, and nanophotonics. Unlike surface plasmon polariton (SPP), the current studies regarding LSPR as biosensor were restricted in probing the extinction spectra, and thus limit the performance in biosensing and bioimaging. Here, we reveal that optical phase of LSPR provides an acute change at resonance beyond extinction spectra, which permits an ultra-high sensitivity in phase interrogation.

Development of a surface plasmon resonance biosensor for real-time detection of osteogenic differentiation in live mesenchymal stem cells.

Surface plasmon resonance (SPR) biosensors have been recognized as a useful tool and widely used for real-time dynamic analysis of molecular binding affinity because of its high sensitivity to the change of the refractive index of tested objects. The conventional methods in molecular biology to evaluate cell differentiation require cell lysis or fixation, which make investigation in live cells difficult. In addition, a certain amount of cells are needed in order to obtain adequate protein or messenger ribonucleic acid for various assays.

Characteristics of subgingival calculus detection by multiphoton fluorescence microscopy.

Subgingival calculus has been recognized as a major cause of periodontitis, which is one of the main chronic infectious diseases of oral cavities and a principal cause of tooth loss in humans. Bacteria deposited in subgingival calculus or plaque cause gingival inflammation, function deterioration, and then periodontitis. However, subgingival calculus within the periodontal pocket is a complicated and potentially delicate structure to be detected with current dental armamentaria, namely dental x-rays and dental probes.

A generalized model of maximizing the sensitivity in intensity-interrogation surface plasmon resonance biosensors.

Intensity interrogation of surface plasmon resonance (IISPR) biosensors possesses the greatest sensitivity beyond other interrogations and is operated at a fixed incident angle to enable real-time analysis without time delay, so that it promises excellent performance in biological/chemical detection and SPR imaging systems. Here we provide a general model to describe its sensitivity based on Lorentz equation and unveil the relation between the sensitivity and the metal thickness. This model presents the dependency between sensitivity and metal thickness, and the optimal thickness of gold layers to maximize the sensitivity in our experiment is 53 nm that agrees well in both measurement and simulation.

All-optical frequency conversion using nonlinear dynamics of semiconductor lasers.

When a semiconductor laser is subject to optical injection, it can enter the period-one dynamics through Hopf bifurcation. Under such nonlinear dynamics, equally and oppositely frequency-shifted optical signals from the injection emerge and are utilized for frequency conversion. Only a typical semiconductor laser is required as the conversion unit, where no pump or probe laser is necessary.

Detection of subgingival calculus through oral gum in vitro using two-photon fluorescence microscopy.

Periodontal disease is one of the main chronic infectious diseases of oral cavity and the principal cause of tooth loss in humans. The main cause of periodontal disease is the bacteria in calculus or plaque to cause the gum inflamed. Therefore detection and removal of subgingival calculus remains important to all periodontal therapy.

Innovative antimicrobial susceptibility testing method using surface plasmon resonance.

Utilizing the ultra sensitivity of surface plasmon resonance (SPR) biosensor to examine drug resistance of bacteria was studied in this research. Susceptible and resistant strains of Escherichia coli JM109 to ampicillin and those of Staphylococcus epidermidis to tetracycline, served as a blind test, were examined. The bacteria adhered on the Au thin film was treated by the injection of antibiotic flow.

Complete phase and amplitude synchronization of broadband chaotic optical fields generated by semiconductor lasers subject to optical injection.

A direct experimental observation of phase synchronization, amplitude synchronization, and frequency locking for the high-frequency broadband chaotic optical fields of the transmitter and the receiver is demonstrated in a fully optical system, where its chaotic optical wave form is generated through the high-speed nonlinearity of semiconductor lasers subject to optical injection. This experimentally achieved chaotic synchronous scenario is verified as identical chaos synchronization by observing several key characteristics of chaos synchronization in this system. The observation at the frequency detuning, the phase sensitivity, and the effect of mismatch at the injection strength from the master laser and match at the laser output power is in good agreement with the theoretical analysis of this system.