Photodynamic inactivation of microorganisms known as antibacterial photodynamic therapy (APDT) is one of the most promising and innovative approaches for the destruction of pathogenic microorganisms. Among the photosensitizers (PSs), compounds based on cationic porphyrins/metalloporphyrins are most successfully used to inactivate microorganisms. Series of meso-substituted cationic pyridylporphyrins and metalloporphyrins with various peripheral groups in the third and fourth positions of the pyrrole ring have been synthesized in Armenia. The aim of this work was to determine and test the most effective cationic porphyrins and metalloporphyrins with high photoactivity against Gram negative and Gram positive microorganisms. It was shown that the synthesized cationic pyridylporphyrins/metalloporphyrins exhibit a high degree of phototoxicity towards both types of bacteria, including the methicillinresistant S. aureus strain. Zinc complexes of porphyrins are more phototoxic than metal-free porphyrin analogs. The effectiveness of these Zn–metalloporphyrins on bacteria is consistent with the level of singlet oxygen generation. It was found that the high antibacterial activity of the studied cationic porphyrins/metalloporphyrins depends on four factors: the presence in the porphyrin macrocycle of a positive charge (+4), a central metal atom (Zn2tT and hydrophobic peripheral functional groups as well as high values of quantum yields of singlet oxygen. The results indicate that meso-substituted cationic pyridylporphyrins/metalloporphyrins can find wider application in photoinactivation of bacteria than anionic or neutral PSs usually used in APDT.

High-grade squamous intraepithelial lesion (HSIL) is regarded as a serious precancerous state of cervix, and it is easy to progress into cervical invasive carcinoma which highlights the importance of earlier diagnosis and treatment of cervical lesions. Pathologists examine the biopsied cervical epithelial tissue through a microscope. The pathological examination will take a long time and sometimes results in high inter- and intra-observer variability in outcomes. Polarization imaging techniques have broad application prospects for biomedical diagnosis such as breast, liver, colon, thyroid and so on. In our team, we have derived polarimetry feature parameters (PFPs) to characterize microstructural features in histological sections of breast tissues, and the accuracy for PFPs ranges from 0.82 to 0.91. Therefore, the aim of this paper is to distinguish automatically microstructural features between HSIL and cervical squamous cell carcinoma (CSCC) by means of polarization imaging techniques, and try to provide quantitative reference index for pathological diagnosis which can alleviate the workload of pathologists. Polarization images of the H&E stained histological slices were obtained by Mueller matrix microscope. The typical pathological structure area was labeled by two experienced pathologists. Calculate the polarimetry basis parameter (PBP) statistics for this region. The PBP statistics (stat PBPs) are screened by mutual information (MI) method. The training method is based on a linear discriminant analysis (LDA) classifier which finds the most simplified linear combination from these stat PBPs and the accuracy remains constant to characterize the specific microstructural feature quantitatively in cervical squamous epithelium. We present results from 37 clinical patients with analysis regions of cervical squamous epithelium. The accuracy of PFP for recognizing HSIL and CSCC was 83.8% and 87.5%, respectively. This work demonstrates the ability of PFP to quantitatively characterize the cervical squamous epithelial lesions in the H&E pathological sections. Significance: Polarization detection technology provides an e±cient method for digital pathological diagnosis and points out a new way for automatic screening of pathological sections.

The 9th Chinese–Russian Workshop on Biophotonics and Biomedical Optics was held online on 28–30 September 2020. The bilateral workshop brought together both Russian and Chinese scientists, engineers, and clinical researchers from a variety of disciplines engaged in applying optical science, photonics, and imaging technologies to problems in biology and medicine. During the workshop, 2 plenary lectures, 35 invited presentations, 5 oral presentations, and 8 internet reports were presented. This special issue selects some papers from the attendees and includes both research and review articles.

The anti-amyloid-β (anti-Aβ) fibrils and soluble oligomers antibody aducanumab were approved to effectively slow down the progression of Alzheimer's disease (AD) at higher doses in 2019, reaffirming the therapeutic effects of targeting the core pathology of AD. A timely and accurate diagnosis in the prodromal or pre-dementia stage of AD is essential for patient recruitment, stratification, and monitoring of treatment effects. AD core biomarkers amyloid-β (Aβ1β42), total tau (t-tau), and phosphorylated tau (p-tau) have been clinically validated to reflect AD-type pathological changes through cerebrospinal fluid (CSF) measurement or positron-emission tomography (PET) and found to have high diagnostic performance for AD identification in the stage of mild cognitive impairment. The development of ultrasensitive immunoassay technology enables AD pathological proteins such as tau and neurofilament light (NFL) to be measured in blood samples. However, combined biomarker detection or targeting multiple biomarkers in immunoassays will increase detection sensitivity and specificity and improve diagnostic accuracy. This review summarizes and analyzes the performance of current detection methods for early diagnosis of AD, and provides a concept of detection method based on multiple biomarkers instead of a single target, which may become a potential tool for early diagnosis of AD in the future.

Diabetes mellitus (DM) is a kind of metabolic disorder characterized by chronic hyperglycemia and glucose intolerance due to absolute or relative lack of insulin, leading to chronic damage of vasculature within various organ systems. These detrimental effects on the vascular networks will result in the development of various diseases associated with microvascular injury. Modern optical imaging techniques provide essential tools for accurate evaluation of the structural and functional changes of blood vessels down to capillaries level, which can offer valuable insight on understanding the development of DM-associated complications and design of targeted therapy. This review will briefly introduce the DM-induced structural and functional alterations of vasculature within different organs such as skin, cerebrum and kidneys, as well as how novel optical imaging techniques facilitate the studies focusing on exploration of these pathological changes of vasculature caused by DM both in-vivo and ex-vivo.

The size and shape of the foveal avascular zone (FAZ) have a strong positive correlation with several vision-threatening retinovascular diseases. The identification, segmentation and analysis of FAZ are of great significance to clinical diagnosis and treatment. We presented an adaptive watershed algorithm to automatically extract FAZ from retinal optical coherence tomography angiography (OCTA) images. For the traditional watershed algorithm, "over-segmentation" is the most common problem. FAZ is often incorrectly divided into multiple regions by redundant "dams". This paper analyzed the relationship between the "dams" length and the maximum inscribed circle radius of FAZ, and proposed an adaptive watershed algorithm to solve the problem of "over-segmentation". Here, 132 healthy retinal images and 50 diabetic retinopathy (DR) images were used to verify the accuracy and stability of the algorithm. Three ophthalmologists were invited to make quantitative and qualitative evaluations on the segmentation results of this algorithm. The quantitative evaluation results show that the correlation coefficients between the automatic and manual segmentation results are 0.945 (in healthy subjects) and 0.927 (in DR patients), respectively. For qualitative evaluation, the percentages of "perfect segmentation" (score of 3) and "good segmentation" (score of 2) are 99.4% (in healthy subjects) and 98.7% (in DR patients), respectively. This work promotes the application of watershed algorithm in FAZ segmentation, making it a useful tool for analyzing and diagnosing eye diseases.

The influence of ischemia–reperfusion (I/R) action on pancreatic blood flow (PBF) and the development of acute pancreatitis (AP) in laboratory rats is evaluated in vivo by using the laser speckle contrast imaging (LSCI). Additionally, the optical properties in norm and under condition of AP in rats were assessed using a modified integrating sphere spectrometer and inverse Monte Carlo (IMC) software. The results of the experimental study of microcirculation of the pancreas in 82 rats in the ischemic model are presented. The data obtained confirm the fact that local ischemia and changes in the blood flow velocity of the main vessels cause and provoke acute pancreatitis.

Cone photoreceptor cell identification is important for the early diagnosis of retinopathy. In this study, an object detection algorithm is used for cone cell identification in confocal adaptive optics scanning laser ophthalmoscope (AOSLO) images. An effectiveness evaluation of identification using the proposed method reveals precision, recall, and F1-score of 95.8%, 96.5%, and 96.1%, respectively, considering manual identification as the ground truth. Various object detection and identification results from images with different cone photoreceptor cell distributions further demonstrate the performance of the proposed method. Overall, the proposed method can accurately identify cone photoreceptor cells on confocal adaptive optics scanning laser ophthalmoscope images, being comparable to manual identification.

Intracranial hypertension is a serious threat to the health of neurosurgical patients. At present, there is a lack of a safe and effective technology to monitor intracranial pressure (ICP) accurately and nondestructively. In this paper, based on near infrared technology, the continuous nondestructive monitoring of ICP change caused by brain edema was studied. The rat brain edema models were constructed by lipopolysaccharide. The ICP monitor and the self-made near infrared tissue parameter measuring instrument were used to monitor the invasive intracranial pressure and the reduced scattering coe±cient of brain tissue during the brain edema development. The results showed that there was a negative correlation between the reduced scattering coe±cient (690nm and 834nm) and ICP, and then the mathematical model was established. The experimental results promoted the development of nondestructive ICP monitoring based on near infrared technology.

Myelin sheaths wrapping axons are key structures that help maintain the propagation speed of action potentials in both central and peripheral nervous systems (CNS and PNS). However, noninvasive, deep imaging technologies visualizing myelin sheaths in the digital skin in vivo are lacking in animal models. 3-photon fluorescence (3PF) imaging excited at the 1700-nm window enables deep imaging of myelin sheaths, but necessitates labeling by exogenous fluorescent dyes. Since myelin sheaths are lipid-rich structures which generate strong third-harmonic signals, in this paper, we perform a detailed comparative experimental study of both third-harmonic generation (THG) and 3PF imaging in the mouse digital skin in vivo. Our results show that THG imaging also enables visualization of myelin sheaths deep in the mouse digital skin, which shows colocalization with 3PF signals from labeled myelin sheaths. Besides its superior label-free advantage, THG does not suffer from photobleaching due to its 3PF property.

Photodynamic antibacterial therapy shows great potential in bacterial infection and the reactive oxygen species (ROS) production of the photosensitizers is crucial for the therapeutic effect. Introducing heavy atoms is a common strategy to enhance photodynamic performance, while dark toxicity can be induced to impede further clinical application. Herein, a novel halogen-free photosensitizer Aza-BODIPY-BODIPY dyad NDB with an orthogonal molecular configuration was synthesized for photodynamic antibacterial therapy. The absorption and emission peaks of NDB photosensitizer in toluene were observed at 703 nm and 744 nm, respectively. The fluorescence (FL) lifetime was measured to be 2.8 ns in toluene. Under 730 nm laser illumination, the ROS generation capability of NDB was 3-fold higher than that of the commercial ICG. After nanoprecipitation, NDB NPs presented the advantages of high photothermal conversion efficiency (39.1%), good photostability, and excellent biocompatibility. More importantly, in vitro antibacterial assay confirmed that the ROS and the heat generated by NDB NPs could extirpate methicillin-resistant S. aureus effectively upon exposure to 730 nm laser, suggesting the potential application of NDB NPs in photo-initiated antibacterial therapy.

This study investigated the neural mechanisms located in the prefrontal cortex (PFC) involved in maintaining addictive-like eating behavior. Therefore, we aimed to fill a gap in the existing literature and help clarify the food addiction (FA) cycle by inspecting the relationship between the executive control and psychopathology involved in the FA cycle. Twenty-three students recruited from the University of Macau participated in this study. We investigated a hemodynamic response captured by NIRS recordings, activated during n-back, set-shifting, and go/nogo paradigms. Moreover, we investigated the FA symptoms through the YFAS clinical inventory to better understand the relationship between hemodynamic response and clinical symptomatology in college students. First, the hemodynamic findings confirm that altered cognitive control in executive function performance appears to be linked to addictive-like eating behaviors, which in turn confirms a circuit similarity between FA and the substance abuse population (SUD) as reported in previous fMRI studies. Secondly, the psychological findings confirm the significant association between the working memory deficits and symptoms severity which suggest the role of self-control and regulation in limiting the storage resources as a potential trigger to develop overconsumption episodes in the FA cycle. Our findings highlight how disrupted self-control and regulation of craving and negative affect induced by mental imagery might shape and overload the working memory storage as a potential trigger to develop binge eating episodes to maintain the FA cycle. In conclusion, the use of fNIRS in the context of eating disorders studies represents a valuable application, noninvasive, and patientfriendly tool, providing new insights into understanding the addiction cycle and treatment guidelines.

The aim of this study is to detect whether the quantitative textural features of optical coherence tomography angiography (OCTA) images can be used to detect the eyes in the early stage of diabetic retinopathy (DR) from eyes with diabetes and no DR (NDR). Textural features including fractal dimension, contrast, correlation, entropy, energy, and homogeneity were calculated from the OCTA images. The Student's t-test was performed to identify the textural features that can be able to detect DR in the early stage. The area under the receiver operating characteristic (AUROC) curves, sensitivity, and specificity were calculated between the study groups. Our results indicated that the fractal dimension in ICP and SVP and the correlation in SVC showed the statistical significance between mild NPDR patients and NDR patients. The ROC analysis results showed that the AUROC of the fractal dimension in ICP was 0.736 with 0.773 sensitivity and 0.700 specificity. The cutoff point in ICP was 2.616. The OCTA-based fractal dimension was able to discriminate diabetic eyes with early retinopathy from healthy and NDR with higher sensitivity and specificity. The OCTA-based correlation showed the power to differentiate the mild NPDR eyes from the normal healthy and diabetic eyes. These results suggest that texture-based features of OCTA have the potential to assist in the assessment of therapeutic interventions to prevent early DR in diabetic subjects.