Simultaneous noninvasive ultrasensitive detection of prostate specific antigen and lncRNA PCA3 using multiplexed dual optical microfibers with strong plasmonic nanointerfaces.

Low accuracy of diagnosing prostate cancer (PCa) was easily caused by only assaying single prostate specific antigen (PSA) biomarker. Although conventional reported methods for simultaneous detection of two specific PCa biomarkers could improve the diagnostic efficiency and accuracy, low detection sensitivity restrained their use in extreme early-stage PCa clinical assay applications. In order to overcome above drawbacks, this paper herein proposed a multiplexed dual optical microfibers separately functionalized with gold nanorods (GNRs) and Au nanobipyramids (Au NBPs) nanointerfaces with strong localized surface plasmon resonance (LSPR) effects. The sensors could simultaneously detect PSA protein biomarker and long noncoding RNA prostate cancer antigen 3 (lncRNA PCA3) with ultrahigh sensitivity and remarkable specificity. Consequently, the proposed dual optical microfibers multiplexed biosensors could detect the PSA protein and lncRNA PCA3 with ultra-low limit-of-detections (LODs) of 3.97 × 10-15 mol/L and 1.56 × 10-14 mol/L in pure phosphorus buffer solution (PBS), respectively, in which the obtained LODs were three orders of magnitude lower than existed state-of-the-art PCa assay technologies. Additionally, the sensors could discriminate target components from complicated physiological environment, that showing noticeable biosensing specificity of the sensors. With good performances of the sensors, they could successfully assay PSA and lncRNA PCA3 in undiluted human serum and urine simultaneously, respectively. Consequently, our proposed multiplexed sensors could real-time high-sensitivity simultaneously detect complicated human samples, that providing a novel valuable approach for the high-accurate diagnosis of early-stage PCa individuals.

Energy focusability of spatial incoherent beam combining for pulse laser propagation in marine atmosphere.

In this study, we have deduced the generalized scintillation index of the plane wave and plane wave structure function based on the modified non-Kolmogorov power spectrum of atmospheric refractive index with the spectrum power index α. In addition, we have analyzed the fluctuation of atmospheric density due to thermal blooming. Based on the interaction of six beams in thermal blooming, the thermal phase screening and intensity distribution are simulated. Under the influence of atmospheric turbulence and thermal blooming, the six-beam combination is then simulated numerically to obtain the equivalent radius with long exposure (RL), power in the bucket (PIB), Strehl ratio (SR), and peak value of intensity (Ip). Results show that PIB, Ip, and SR of the pulse beam combination decrease with an increase in α; however, RL operates in reverse mode and the short pulse durations reduce the thermal blooming. Moreover, laser of short duration cannot generate high ring energy on the target.

Optical-resolution functional gastrointestinal photoacoustic endoscopy based on optical heterodyne detection of ultrasound.

Photoacoustic endoscopy shows promise in the detection of gastrointestinal cancer, inflammation, and other lesions. High-resolution endoscopic imaging of the hemodynamic response necessitates a small-sized, high-sensitivity ultrasound sensor. Here, we utilize a laser ultrasound sensor to develop a miniaturized, optical-resolution photoacoustic endoscope. The sensor can boost the acoustic response by a gain factor of ωo/Ω (the frequency ratio of the signal light and measured ultrasound) by measuring the acoustically induced optical phase change. As a result, we achieve a noise-equivalent pressure density (NEPD) below 1.5 mPa·Hz-1/2 over the measured range of 5 to 25 MHz. The heterodyne phase detection using dual-frequency laser beams of the sensor can offer resistance to thermal drift and vibrational perturbations. The endoscope is used to in vivo image a rat rectum and visualize the oxygen saturation changes during acute inflammation, which can hardly be observed with other imaging modalities.

High spatiotemporal resolution optoacoustic sensing with photothermally induced acoustic vibrations in optical fibres.

Optoacoustic vibrations in optical fibres have enabled spatially resolved sensing, but the weak electrostrictive force hinders their application. Here, we introduce photothermally induced acoustic vibrations (PTAVs) to realize high-performance fibre-based optoacoustic sensing. Strong acoustic vibrations with a wide range of axial wavenumbers kz are photothermally actuated by using a focused pulsed laser. The local transverse resonant frequency and loss coefficient can be optically measured by an intra-core acoustic sensor via spectral analysis. Spatially resolved sensing is further achieved by mechanically scanning the laser spot. The experimental results show that the PTAVs can be used to resolve the acoustic impedance of the surrounding fluid at a spatial resolution of approximately 10 µm and a frame rate of 50 Hz. As a result, PTAV-based optoacoustic sensing can provide label-free visualization of the diffusion dynamics in microfluidics at a higher spatiotemporal resolution.

Sensitivity characteristics of broadband fiber-laser-based ultrasound sensors for photoacoustic microscopy.

High-frequency fiber laser sensor is a new acoustic detector for photoacoustic imaging. However, its performance has not been thoroughly studied. Here, we present a comprehensive characterization of a fiber laser sensor for photoacoustic imaging. Ultrasound waves deform the fiber laser cavity and induce frequency changes in the heterodyning output signal. The sensitivity peaks at 22 MHz, which is associated with an azimuthal mode number l = 2 and a radial mode number n = 1. The broadband acoustic sensitivity in terms of frequency shift is 2.25 MHz/kPa and the noise-equivalent pressure reaches 45 Pa with a sampling rate of 100 MHz. The 3-dB bandwidth is 18 MHz for spherical-wave detection. We characterized the spatial distribution of acoustic sensitivity. The sensitivity along the fiber longitudinal direction varies with the laser spatial mode and is determined by the grating and cavity parameters. The sensitivity at the azimuthal direction presents a |cos(2θ)| dependence as a result of fiber core asymmetry. In the radial direction, the sensitivity is inversely proportional to the square root of the distance between the source and the detector. The acoustic sensitivity can be enhanced by reducing the cavity length. We experimentally show that a short sensor can enhance the contrast and penetration depth of PAM than a long one.

Highly sensitive fiber laser ultrasound hydrophones for sensing and imaging applications: publisher's note.

This note corrects the range of acoustic frequencies mentioned in the opening paragraph of Opt. Lett.41, 4530 (2016)OPLEDP0146-959210.1364/OL.41.004530 as having rarely been investigated.

Highly sensitive fiber laser ultrasound hydrophones for sensing and imaging applications.

We have developed highly sensitive photonic ultrasound hydrophones based on polymer-packaged dual-polarization-mode fiber lasers. The incident ultrasound wave is scattered by the polymer cylinder due to the difference in elastic property. The scattered wave can drive harmonic vibration of the cylinder and result in optical response in terms of beat-frequency variation of the laser output. Experimental results exhibit a broadband ultrasound response at frequencies below 1 MHz. The individual vibration modes are excited by the ultrasound waves with different efficiencies, yielding a frequency-dependent response. A hydrophone with a diameter of 5 mm presents a detection limit of 2 mPa/Hz1/2 at 200 kHz. We further demonstrate its capability of ultrasound imaging for applications in underwater acoustics and sonar systems.