Hepatic cirrhosis and recovery as reflected by Raman spectroscopy: information revealed by statistical analysis might lead to a prognostic biomarker

Reviews of bio-orthogonal probes in bioscience by stimulated Raman scattering microscopy

Stimulated Raman scattering (SRS) microscopy, is a nonlinear optical imaging method for visualizing chemical content based on molecular vibrational bonds, with high sensitivity, resolution, speed, and specificity. In the current review, we provided a comprehensive and critical review of the most recent developments in the field of SRS in combination with bio-orthogonal Raman tags or labels in bioscience. Firstly, we introduced the fundamentals of SRS microscopy and the theory principle of bio-orthogonal Raman tags. In particular, present the applications of each kind of bio-orthogonal Raman tags, including heavy water (D2O), stable isotope probes (SIP), and triple-bonds tags. And shared our vision for the remaining challenges, research needs, and potential future breakthroughs for SRS technology lastly. We envision that the advanced SRS imaging and analysis will be a major force in future biological discovery.

A novel alternative strategy for monitoring and insight into liver fibrosis progression: The combination of surface-enhanced Raman spectroscopy (SERS) and gut microbiota

Nowadays, the studies on the interaction and relationship between the intestinal microorganisms and liver diseases are increasing. However, it is still a huge challenge for the in-depth investigation and dynamic monitoring of such a complex network. Herein, a significant discovery was made. A strong association between gut microbial structural and functional genomics and SERS spectra of hepatocytes were revealed. Based on the study of gut microbes and SERS spectra, complementary information could be provided for the mechanism analysis of related diseases. Liver fibrosis, a chronic liver disease that lack specific cure was thus comprehensive studied. Liver targeting gold nanoparticle dimers were prepared as the SERS tags, and abundant SERS peak signals were acquired. Meanwhile, the gut microbiomes were also comparative studied. The changes of carbohydrates and lipids in liver cells were observed at the early stages of liver fibrosis, and TLR4 (toll-like receptors 4) was activated to elicit immune responses. Then again, oxidative stress, endotoxin and serum inflammatory factors were the major observations at the late stages. The SERS signals and the microbiome analysis were well confirmed and complemented each other, which suggested that the detection strategy could be another valuable method for the "gut-liver axis" study.

Raman Scattering-Based Optical Sensing Of Chronic Liver Diseases

Chronic liver diseases (CLDs) are a major public health problem. Despite the progress achieved in fighting against viral hepatitis, the emergence of non-alcoholic fatty liver disease might pose a serious challenge to the public's health in the coming decades. Medical management of CLDs represents a substantial burden on the public health infrastructures. The health care cost of these diseases is an additional burden that weighs heavily on the economies of developing countries. Effective management of CLDs requires the adoption of reliable and cost-effective screening and diagnosing methods to ensure early detection and accurate clinical assessment of these diseases. Vibrational spectroscopies have emerged as universal analytical methods with promising applications in various industrial and biomedical fields. These revolutionary analytical techniques rely on analyzing the interaction between a light beam and the test sample to generate a spectral fingerprint. This latter is defined by the analyte's chemical structure and the molecular vibrations of its functional groups. Raman spectroscopy and surface-enhanced Raman spectroscopy have been used in combination with various chemometric tests to diagnose a wide range of malignant, metabolic and infectious diseases. The aim of the current review is to cast light on the use of these optical sensing methods in the diagnosis of CLDs. The vast majority of research works that investigated the potential application of these spectroscopic techniques in screening and detecting CLDs were discussed here. The advantages and limitations of these modern analytical methods, as compared with the routine and gold standard diagnostic approaches, were also reviewed in details.

Rapid, label-free histopathological diagnosis of liver cancer based on Raman spectroscopy and deep learning

Biopsy is the recommended standard for pathological diagnosis of liver carcinoma. However, this method usually requires sectioning and staining, and well-trained pathologists to interpret tissue images. Here, we utilize Raman spectroscopy to study human hepatic tissue samples, developing and validating a workflow for in vitro and intraoperative pathological diagnosis of liver cancer. We distinguish carcinoma tissues from adjacent non-tumour tissues in a rapid, non-disruptive, and label-free manner by using Raman spectroscopy combined with deep learning, which is validated by tissue metabolomics. This technique allows for detailed pathological identification of the cancer tissues, including subtype, differentiation grade, and tumour stage. 2D/3D Raman images of unprocessed human tissue slices with submicrometric resolution are also acquired based on visualization of molecular composition, which could assist in tumour boundary recognition and clinicopathologic diagnosis. Lastly, the potential for a portable handheld Raman system is illustrated during surgery for real-time intraoperative human liver cancer diagnosis.

SERS diagnosis of liver fibrosis in the early stage based on gold nanostar liver targeting tags

In order to realize the accurate and early diagnosis of liver fibrosis, a long slow pathological process which may lead to cirrhosis or even liver cancer, liver targeting tags made up of gold nanostars and glycyrrhetinic acid are reported in this paper. Gold nanostars (GNSs) and GNS liver targeting tags (GLTTs) were injected into model mice with stage S1 liver fibrosis and normal mice via the tail vein respectively, then the SERS spectra were collected. GLTTs had a better detection effect on liver tissue than unmodified GNSs (12.85 times), and better detection reproducibility as well. Moreover, according to the MTT and survival analysis experiments, GLTTs also had better biocompatibility. Hence, the changes of 10 SERS signals and other substances in the early stage of liver fibrosis were analyzed at the molecular level, and the SERS characteristic peaks that could be used for the diagnosis of early liver fibrosis were screened out. Revealed by the experimental results, the GLTTs designed and prepared were applicable to the efficient SERS detection of early liver fibrosis in mice, and the strategy we have proposed might be a potential approach for the early diagnosis of this disease in clinics.

Imaging the invisible-Bioorthogonal Raman probes for imaging of cells and tissues

A revolutionary avenue for vibrational imaging with super-multiplexing capability can be seen in the recent development of Raman-active bioortogonal tags or labels. These tags and isotopic labels represent groups of chemically inert and small modifications, which can be introduced to any biomolecule of interest and then supplied to single cells or entire organisms. Recent developments in the field of spontaneous Raman spectroscopy and stimulated Raman spectroscopy in combination with targeted imaging of biomolecules within living systems are the main focus of this review. After having introduced common strategies for bioorthogonal labeling, we present applications thereof for profiling of resistance patterns in bacterial cells, investigations of pharmaceutical drug-cell interactions in eukaryotic cells and cancer diagnosis in whole tissue samples. Ultimately, this approach proves to be a flexible and robust tool for in vivo imaging on several length scales and provides comparable information as fluorescence-based imaging without the need of bulky fluorescent tags.

Confocal Raman microscopy in life sciences

Microscopy techniques are widely used in life sciences to study cells and tissues. Fluorescence microscopy, for example, is a very common method in many laboratories. While reliable and strong fluorescence signals are a clear advantage of this method, the labelling procedure with fluorescent dyes, the availability of required antibodies or the potentially necessary genetic modifications of the studied organism all introduce potential complications. By contrast, confocal Raman microscopy is a label-free and non-destructive imaging technique. In contrast to infrared microscopy, it is easily applicable in aqueous environments. Different microscope setups and combinations allow for the examination of various solid and liquid samples, even in their typical environments. The article demonstrates the analyzing capability of confocal Raman microscopy and correlative techniques through application examples of eukaryotic and prokaryotic cells, and cancerous and normal tissues and shows how confocal Raman microscopy provides valuable information for a more comprehensive understanding of the investigated sample.

Photonic monitoring of treatment during infection and sepsis: development of new detection strategies and potential clinical applications

Despite the strong decline in the infection-associated mortality since the development of the first antibiotics, infectious diseases are still a major cause of death in the world. With the rising number of antibiotic-resistant pathogens, the incidence of deaths caused by infections may increase strongly in the future. Survival rates in sepsis, which occurs when body response to infections becomes uncontrolled, are still very poor if an adequate therapy is not initiated immediately. Therefore, approaches to monitor the treatment efficacy are crucially needed to adapt therapeutic strategies according to the patient's response. An increasing number of photonic technologies are being considered for diagnostic purpose and monitoring of therapeutic response; however many of these strategies have not been introduced into clinical routine, yet. Here, we review photonic strategies to monitor response to treatment in patients with infectious disease, sepsis, and septic shock. We also include some selected approaches for the development of new drugs in animal models as well as new monitoring strategies which might be applicable to evaluate treatment response in humans in the future. Figure Label-free probing of blood properties using photonics.

A Critical Review on Ultrasensitive, Spectroscopic-based Methods for High-throughput Monitoring of Bacteria during Infection Treatment

The world is in the midst of a pre-emptive public health emergency, one that is just as dramatic as the global aggressive viruses-related crises (Ebola, Zika, or SARS), but not as visible. The "superbugs" and their antimicrobial resistance do not cause much public alarm or awareness, but provoke financial losses of $100 trillion annually (WHO, http://www.who.int/mediacentre/commentaries/superbugs-action-now/en/ ). This status quo review offers an overview of ultrasensitive methods for high-throughput monitoring of bacteria during infection treatment, the effects of antibiotics on bacteria at single-cell level and the challenges we will face in their detection due to the extraordinary capability of these "superbugs" to gain and constantly improve multiresistance to antibiotics. A special emphasis is put on the ultrasensitive spectroscopic-based analysis techniques, using nanotechnology or not necessarily, that are more and more promising alternatives to conventional culture-based ones. The particular case of Mycobacteria detection is discussed based on recent reported work.