Autophagy is an essential degradative process that governs the renewal of organelle and maintains the homeostasis of cellular microenvironment. Its dysregulation has been demonstrated to be an indicator for neuroinflammation. To elucidate the interrelationship between neuroinflammation and autophagy, optical probes are ideal tools as they offer a number of advantages such as high spatiotemporal resolution and non-invasive sensing, which help to visualize the physiological and pathological functions of interested analytes. However, single autophagy parameter-response probes may generate false-positive results since they cannot distinguish between neuroinflammation and other autophagic stimuli. In contrast, chemosensors that respond to two (or more) targets can improve selectivity by qualifying response conditions. Herein, a \"dual-key-and-lock\" strategy was applied to construct probe (Vis-NO) to selectively recognize autophagy under inflammation out of other stimuli. The red fluorescence of Vis-NO was lit up only in the simultaneously presence of high viscosity and nitric oxide (NO) in lysosome. Due to the characteristics of high viscosity and overexpressed NO within lysosomes, Vis-NO could be used to selectively identify autophagy during neuroinflammation, providing expanding insights into the interrelationship between autophagy, neuroinflammation and stroke in pathology, and informing about the mechanisms through which autophagy regulates inflammation.

A highly affordable, sensitive and portable detection platform for the quantitative identification of sodium copper chlorophyllin (SCC) in food and environment is a crucial need. Even though many carbon dots (CDs) based sensors have been developed, few reports on using CDs as optical probes for SCC detection have been published so far. In this paper, orange luminescent CDs (OLCDs) were prepared via solvothermal method, which have high fluorescence quantum yield (27.20 %) and excellent photostability. OLCDs can detect SCC via inner filter effect (IFE), with fast response, high selectivity, outstanding sensitivity and superior anti-interference ability. Benefiting from the remarkable properties of OLCDs, a portable sensing platform was triumphantly constructed, which facilitated the in situ, real-time quantitative determination of SCC in diverse actual samples, by catching the fluorescence change of OLCDs-based paper sensors via smartphone RGB colorimetric analysis. This first CDs-based smart sensing system displays great potential for quantification of SCC in various fields.

The use of an optical probe for fluorescence detection combined with direct immersion single-drop microextraction has been demonstrated as an innovative approach. The optical probe served both as a drop holder for extractant and as a measuring device which made it possible to eliminate the use of cuvettes. A laser and a light emitting diode (LED) were tested as possible light sources. Both of them showed comparable results. However, given the much smaller half-band width of the laser radiation, its use has proven to be preferable since background correction can be eliminated. Direct immersion single-drop microextraction of an ionic association complex of rhodamine 6G with picric acid with subsequent fluorescent detection (λex was 532 nm and 525 nm for laser and LED, respectively; λem was 560 nm for both laser and LED) was used a model system to evaluate the new approach. The extractant phase was a 55 μL amyl acetate microdrop fixed in the optical part of the probe. LOD, LOQ and linear calibration range were found as 0.14, 0.48 and 0.5-10 nmol L-1, and 0.15, 0.50 and 0.5-5 nmol L-1 for laser and LED light sources, respectively. The accuracy of the method was assessed by analyzing real water samples.

OBJECTIVE: Staphylococcus aureus is the most common and impactful multi-drug resistant pathogen implicated in (periprosthetic) joint infections (PJI) and fracture-related infections (FRI). Therefore, the present proof-of-principle study was aimed at the rapid detection of S. aureus in synovial fluids and biofilms on extracted osteosynthesis materials through bacteria-targeted fluorescence imaging with the \'smart-activatable\' DNA-based AttoPolyT probe. This fluorogenic oligonucleotide probe yields large fluorescence increases upon cleavage by micrococcal nuclease, an enzyme secreted by S. aureus.
METHODS: Synovial fluids from patients with suspected PJI and extracted osteosynthesis materials from trauma patients with suspected FRI were inspected for S. aureus nuclease activity with the AttoPolyT probe. Biofilms on osteosynthesis materials were imaged with the AttoPolyT probe and a vancomycin-IRDye800CW conjugate (vanco-800CW) specific for Gram-positive bacteria.
RESULTS: 38 synovial fluid samples were collected and analyzed. Significantly higher fluorescence levels were measured for S. aureus-positive samples compared to, respectively, other Gram-positive bacterial pathogens (p < 0.0001), Gram-negative bacterial pathogens (p = 0.0038) and non-infected samples (p = 0.0030), allowing a diagnosis of S. aureus-associated PJI within 2 h. Importantly, S. aureus-associated biofilms on extracted osteosynthesis materials from patients with FRI were accurately imaged with the AttoPolyT probe, allowing their correct distinction from biofilms formed by other Gram-positive bacteria detected with vanco-800CW within 15 min.
CONCLUSIONS: The present study highlights the potential clinical value of the AttoPolyT probe for fast and accurate detection of S. aureus infection in synovial fluids and biofilms on extracted osteosynthesis materials.

Endometrial cancer is one of the common gynecological malignancies, and its incidence has been increasing year by year in recent years, raising higher requirements for its rapid diagnosis. In this article, gold nanorods (AuNRs) with localized surface plasmon resonance properties (LSPR) has used to prepare AuNRs-antibody to waveform protein (AuNRs-AntiVimentin) optical probes, and a new method has been constructed that could rapidly detect and identify endometrial cancer tissue sections by polarized light microscopy. AuNRs were prepared by seed growth method using gold chloride as raw material, and the morphology of AuNRs and the optical characteristics of AuNRs-AntiVimentin has characterized by transmission electron microscopy (TEM), ultraviolet-visible spectroscopy (UV-Vis), and zeta potential; immunohistochemistry (IHC) and AuNRs-AntiVimentin optical probes have used to detect clinical endometrial cancer, respectively. The AuNRs-AntiVimentin optical probe has been used to detect endometrial cancer tissue sections and found to have good bio-specificity, with no significant difference in the detection of AuNRs-AntiVimentin compared with conventional IHC techniques (p > .05). An optical probe generated by coupling AuNRs with Vimentin antibodies has been obtained to detect and identify endometrial cancer with simple operation and comparable effect to conventional IHC, providing a new method and idea for the rapid detection of endometrial cancer.

Biodegradable magnesium-based implants offer mechanical properties similar to natural bone, making them advantageous over nonbiodegradable metallic implants. However, monitoring the interaction between magnesium and tissue over time without interference is difficult. A noninvasive method, optical near-infrared spectroscopy, can be used to monitor tissue\'s functional and structural properties. In this paper, we collected optical data from an in vitro cell culture medium and in vivo studies using a specialized optical probe. Spectroscopic data were acquired over two weeks to study the combined effect of biodegradable Mg-based implant disks on the cell culture medium in vivo. Principal component analysis (PCA) was used for data analysis. In the in vivo study, we evaluated the feasibility of using the near-infrared (NIR) spectra to understand physiological events in response to magnesium alloy implantation at specific time points (Day 0, 3, 7, and 14) after surgery. Our results show that the optical probe can detect variations in vivo from biological tissues of rats with biodegradable magnesium alloy \"WE43\" implants, and the analysis identified a trend in the optical data over two weeks. The primary challenge of in vivo data analysis is the complexity of the implant interaction near the interface with the biological medium.

Deep tissue noninvasive high-resolution imaging with light is challenging due to the high degree of light absorption and scattering in biological tissue. Photoacoustic imaging (PAI) can overcome some of the challenges of pure optical or ultrasound imaging to provide high-resolution deep tissue imaging. However, label-free PAI signals from light absorbing chromophores within the tissue are nonspecific. The use of exogeneous contrast agents (probes) not only enhances the imaging contrast (and imaging depth) but also increases the specificity of PAI by binding only to targeted molecules and often providing signals distinct from the background.
We aim to review the current development and future progression of photoacoustic molecular probes/contrast agents.
First, PAI and the need for using contrast agents are briefly introduced. Then, the recent development of contrast agents in terms of materials used to construct them is discussed. Then, various probes are discussed based on targeting mechanisms, in vivo molecular imaging applications, multimodal uses, and use in theranostic applications.
Material combinations are being used to develop highly specific contrast agents. In addition to passive accumulation, probes utilizing activation mechanisms show promise for greater controllability. Several probes also enable concurrent multimodal use with fluorescence, ultrasound, Raman, magnetic resonance imaging, and computed tomography. Finally, targeted probes are also shown to aid localized and molecularly specific photo-induced therapy.
The development of contrast agents provides a promising prospect for increased contrast, higher imaging depth, and molecularly specific information. Of note are agents that allow for controlled activation, explore other optical windows, and enable multimodal use to overcome some of the shortcomings of label-free PAI.

Tuberculosis (TB) is a contagious disease that causes 1.5 million deaths per year globally. Early diagnosis of TB patients is critical to control its spread. However, standard TB diagnostic tests such as sputum culture take days to weeks to produce results. Here, we demonstrate a quick, portable, easy-to-use, and non-invasive optical sensor based on sputum samples for TB detection. The probe uses Raman spectroscopy to detect TB in a patient\'s sputum supernatant. We deploy a machine-learning algorithm, principal component analysis (PCA), on the acquired Raman data to enhance the detection sensitivity and specificity. On testing 112 potential TB patients, our results show that the developed probe\'s accuracy is 100% for true-positive and 93.4% for true-negative. Moreover, the probe correctly identifies patients on TB medication. We anticipate that our work will lead to a viable and rapid TB diagnostic platform.

Formaldehyde, one of the simplest reactive carbonyl substances, is involved in many physiological and pathological processes in living organisms. There is a large amount of data showing that abnormal elevation of formaldehyde is associated with a variety of diseases in the body, such as neurodegenerative diseases, Alzheimer\'s disease, cardiovascular diseases and cancer, and is also a representative carcinogen, so monitoring formaldehyde is of great importance for disease diagnosis and treatment. In this review, In this paper, we summarize and classify the last ten years of probes for the detection of formaldehyde according to different reaction mechanisms and discuss the structures and applications of the probes. Finally, we briefly describe the challenges and possible solutions in this field. We believe that more new probes provide powerful tools to study the function of formaldehyde in living systems.

The diffraction limit is one of the main obstacles in the development of microscopes to analyze the morphology and structure of materials. The main idea of near field scanning optical microscopy (NSOM) is to overcome the diffraction limit using sub-wavelength apertures. In this work, the near-field is simulated in the vicinity of three-dimensional nano-optical apertureless probes. For this purpose, the Helmholtz equation is solved using the boundary element method (BEM). The effects of different parameters on the near field generated in the vicinity of the optical probe are studied. These parameters consist of the length and radius of the probe, the size of the aperture, the angle of the tapered tip, and the geometry of the probe tip. The main advantages of the proposed method are the high accuracy, the very short calculation time, and the ability to calculate the near field inside and outside the optical probe without any approximation.