Equivalent Response Strategy for Sensing Total Biothiols in Human Serums and Living Cells Using a Hemicyanine-Based Self-Immolative Probe.

Biothiols including cysteine (Cys), homocysteine (Hcy), and glutathione (GSH) are crucial in maintaining the redox balance in the body, and the metabolism and transportation of biothiols rely on the coreaction of diverse proteins and enzymes. The abnormal concentrations and metabolism of biothiols are closely associated with many diseases. However, due to the same active reaction site of the sulfydryl group in biothiols, it is inevitable to bear a confused signal of mutual influence on both nonselective detection and discriminate detection, which presents a serious challenge of accurately sensing or imaging the three biothiols. By assigning an α,ß-unsaturated ketone moiety as a Michael acceptor to trigger thiols to complete the irreversible equivalent domino response processes of nucleophilic addition, olefinic bond migration, and self-immolation, a targeted strategy was rationally pointed out, and herein, a hemicyanine-based probe CyOCy was prepared as a proof of strategy demonstration. The new probe could be equivalently lit up by Cys, Hcy, GSH, and even biothiol combinations (Cys/Hcy, Cys/GSH, Hcy/GSH, or Cys/Hcy/GSH) with unified linear ranges, detection limits, and response times. The probe CyOCy has been successfully used for the accurate quantification of total biothiols in the serum samples of healthy persons and coronary heart disease patients. In addition, the probe has been applied for cell screening, exogenous biothiol imaging, and monitoring drug-induced biothiol fluctuations. The purposive thinking of this work may provide an effective avenue for the accurate sensing of multicomponent samples.

Recent Advances in the Fluorescent Probes for Flavinase Activity: Design and Applications.

Flavinases, including monoamine oxidase (MAO-A/MAO-B), quinone oxidoreductase (NQO1), thioredoxin reductase (TrxR), nitroreductase (NTR) and so on, are important redox enzymes in organisms. They are considered as biomarkers of cell energy metabolism and cell vitality. Importantly, their aberrant expression is related to various disease processes. Therefore, the accurate measurement of flavinase is useful for the early diagnosis of diseases, which has aroused great concern in the scientific community. Various methods are also available for the detection of flavinases, fluorescence probes are considered to be one of the best detection methods due to their easy and accurate sensing capability. This review aims to introduce the advances in the design and application of flavinase probes in the last five years. This study focuses on analyzing the design strategies and reaction mechanisms of flavinases fluorescent probes and discusses the current challenges, which will further advance the development of diagnostic and therapeutic approaches for flavinase-related diseases.

Colorimetric discrimination for Stokes polarimetric imaging.

Traditional methods of discrimination for Stokes polarimetric imaging use grayscale images, in which the difference of the polarimetric properties is only reflected by the difference of grayscale. In this paper, we propose a method of colorimetric discrimination and classification for Stokes polarimetric imaging by the composed color polarimetric image, in which the objects with different polarization properties can appear in different colors. We show with real-world experiment that compared with the traditional method for the grayscale Stokes scalar image, the method proposed in this paper has a better performance for distinguishing objects with different polarization properties.

Comparison of femtosecond laser ablation of aluminum in water and in air by time-resolved optical diagnosis.

The dynamic process of material ejection and shock wave evolution during one single femtosecond laser pulse ablation of aluminum target in water and air is experimentally investigated by employing pump-probe technique. Shadowgraphs and digital holograms with high temporal resolution are recorded, which intuitively reveal the characteristics of femtosecond laser ablation in the water-confined environment. The experimental result indicates that the liquid significantly restrict the diffusion of the ejected material, and it has a considerable effect on the attenuation of the shock wave. In addition, the expansion Mach wave generated by the ultrasonic expansion of the shock wave is observed.

Spatial angular multiplexing for enlarging the detected area in off-axis digital holography.

In off-axis digital holography, e.g., for detecting and imaging ultrafast phenomena, the interference region is confined to a limited region due to the short extent of the light pulse along the propagation axis. Therefore, the detected area of the object wavefront is limited. A recording method for enlarging the detected area in the above case is proposed in this Letter, in which multiple interferences between the object and the reference waves are obtained by spatial angular multiplexing. Experimental results demonstrate the validity of this method.

Numerical iterative approach for zero-order term elimination in off-axis digital holography.

A novel numerical iterative approach is proposed to effectively eliminate the zero-order term and to improve the signal-to-noise ratio of the reconstructed image in off-axis digital holography. The iterations are conducted in the spatial domain, resulting in considerable reduction in the computational time and avoiding the subjectivity involved in selecting a filter window in spectral domain. These advantages promote the application of this approach in real-time detection processes. The feasibility of this approach is confirmed by mathematical deductions and numerical simulations, and the robustness of the proposed approach is tested by means of an experimentally obtained hologram.

Single-shot diagnostic for the three-dimensional field distribution of a terahertz pulse based on pulsed digital holography.

In this Letter, a pulsed digital holographic approach for detecting the three-dimensional (3D) field distribution of a freely propagating single terahertz (THz) pulse based on an electro-optic (E-O) sampling technique is proposed, by which the 3D field distribution of a single THz pulse sampled at different time points can be recorded in real-time on a series of subholograms and will be finally reconstructed as a series of two-dimensional spatial electric field distributions in a time series with a time resolution of femtosecond order. Simulation is carried out to demonstrate the process of the implementation, which confirmed the feasibility of the proposal.

Neutrals ejection in intense femtosecond laser ablation.

Time-resolved shadowgraphs and holograms of intense femtosecond laser ablation of aluminum are reported. The different bending trends of interference fringes are found in the ablations of aluminum and other materials at probe wavelengths of 400 and 800 nm, for the first time to our knowledge, which could be attributed to the ejection of massive neutral droplets induced by critical-point phase separation during the second material ejection.

Angular multiplexing in pulsed digital holography for aperture synthesis.

A new aperture-synthesis approach in a pulsed digital holography system for obtaining superresolution is proposed and experimentally demonstrated in which, with only a single laser pulse divided into two trains of subpulses, angular multiplexing can be applied to both the reference beam for different carrier frequency and the object beam for off-axis and on-axis illuminations. Furthermore, in the recording plane, multiple subholograms covering different spatial frequency ranges diffracted from the object can be recorded in a single frame of a CCD. Our analysis and results show that the resolution of the reconstructed image synthesized upon the reconstructed complex amplitudes of the subholograms can be improved effectively.

Pulsed digital holography system recording ultrafast process of the femtosecond order.

We report, for the first time to our knowledge, a pulsed digital microholographic system with spatial angular multiplexing for recording the ultrafast process of the femtosecond order. The optimized design of the two sets of subpulse-train generators in this system makes it possible to implement a digital holographic recording with spatial angular multiplexing of a frame interval of the femtosecond order, while keeping the incident angle of the object beams unchanged. Three pairs of amplitude and phase images from the same view angle digitally reconstructed by the system demonstrated the ultrafast dynamic process of laser-induced ionization of ambient air at a wavelength of 800 nm, with a time resolution of 50 fs and a frame interval of 300 fs.

Color image recognition by use of a joint transform correlator of three liquid-crystal televisions.

We present a joint transform correlator for color image recognition by using three liquid-crystal spatial light modulators. A method for simultaneously obtaining the correlation peaks of red, green, and blue is proposed and experimentally demonstrated.