Review of Biosensors Based on Plasmonic-Enhanced Processes in the Metallic and Meta-Material-Supported Nanostructures.

Surface plasmons, continuous and cumulative electron vibrations confined to metal-dielectric interfaces, play a pivotal role in aggregating optical fields and energies on nanostructures. This confinement exploits the intrinsic subwavelength nature of their spatial profile, significantly enhancing light-matter interactions. Metals, semiconductors, and 2D materials exhibit plasmonic resonances at diverse wavelengths, spanning from ultraviolet (UV) to far infrared, dictated by their unique properties and structures. Surface plasmons offer a platform for various light-matter interaction mechanisms, capitalizing on the orders-of-magnitude enhancement of the electromagnetic field within plasmonic structures. This enhancement has been substantiated through theoretical, computational, and experimental studies. In this comprehensive review, we delve into the plasmon-enhanced processes on metallic and metamaterial-based sensors, considering factors such as geometrical influences, resonating wavelengths, chemical properties, and computational methods. Our exploration extends to practical applications, encompassing localized surface plasmon resonance (LSPR)-based planar waveguides, polymer-based biochip sensors, and LSPR-based fiber sensors. Ultimately, we aim to provide insights and guidelines for the development of next-generation, high-performance plasmonic technological devices.

Dispersion of acid without gastric perforation on ingestion of toilet cleaner: a rare autopsy case.

Toilet cleaner containing hydrochloric acid is a common item found in households all over the world. Due to the availability of the substance, it becomes one of the main contributors to corrosive damage to the gastrointestinal system. This study reports a case of a female in her 50s with an alleged history of ingestion of toilet cleaner an empty bottle of which was found together with a suicide note at the incident site. During the autopsy, the forensic expert made an intriguing observation regarding the dispersion of ingested acid to other organs without gastric perforation. Despite the absence of gastric perforation, the corrosive effects of the ingested acid were evident in various organs, including the liver and spleen. This phenomenon suggests a unique mechanism by which the acid is able to disperse and cause damage beyond the stomach, leading to widespread organ involvement. However, through a comprehensive analysis of the detailed history, typical macroscopic autopsy findings, and chemical analysis reports, it is possible to establish that the cause of death is corrosive acid poisoning. In such cases, further investigation is warranted to gain a better understanding of the underlying mechanisms responsible for the dispersion of the acid and its clinical implications. By delving deeper into these aspects, we can enhance our knowledge and contribute to the field of forensic medicine.

Low-Cost ZnO Spray-Coated Optical Fiber Sensor for Detecting VOC Biomarkers of Diabetes.

A non-invasive optical fiber sensor for detecting volatile organic compounds (VOCs) as biomarkers of diabetes is proposed and experimentally demonstrated. It offers a low-cost and straightforward fabrication approach by implementing a one-step spray coating of a ZnO colloidal solution on a glass optical fiber. The structure of the optical fiber sensor is based on a single-mode fiber-coreless silica fiber-single-mode fiber (SMF-CSF-SMF) structure, where the CSF is the sensor region spliced between two SMFs. The ZnO layer of a higher refractive index coated over the sensing region improves the light interaction with the surrounding medium, leading to sensitivity enhancement. The optical properties, morphology, and elemental composition of the ZnO layer were analyzed. The sensing mechanism of the developed sensor is based on a wavelength interrogation technique showing wavelength shifts when the sensor is exposed to various VOC vapor concentration levels. Various concentrations of the three VOCs (including acetone, isopropanol, and ethanol) ranging from 20% to 100% were tested and analyzed. The sensor noticeably shows a significant response towards acetone vapor, with a better sensitivity of 0.162 nm/% vapor than for isopropanol (0.082 nm/% vapor) and ethanol (0.075 nm/% vapor) vapors. The high sensitivity and selectivity towards acetone, a common biomarker for diabetes, offers the potential for further development of this sensor as a smart healthcare system for monitoring diabetic conditions.

Recent Advances in Sensing Materials Targeting Clinical Volatile Organic Compound (VOC) Biomarkers: A Review.

In general, volatile organic compounds (VOCs) have a high vapor pressure at room temperature (RT). It has been reported that all humans generate unique VOC profiles in their exhaled breath which can be utilized as biomarkers to diagnose disease conditions. The VOCs available in exhaled human breath are the products of metabolic activity in the body and, therefore, any changes in its control level can be utilized to diagnose specific diseases. More than 1000 VOCs have been identified in exhaled human breath along with the respiratory droplets which provide rich information on overall health conditions. This provides great potential as a biomarker for a disease that can be sampled non-invasively from exhaled breath with breath biopsy. However, it is still a great challenge to develop a quick responsive, highly selective, and sensitive VOC-sensing system. The VOC sensors are usually coated with various sensing materials to achieve target-specific detection and real-time monitoring of the VOC molecules in the exhaled breath. These VOC-sensing materials have been the subject of huge interest and extensive research has been done in developing various sensing tools based on electrochemical, chemoresistive, and optical methods. The target-sensitive material with excellent sensing performance and capturing of the VOC molecules can be achieved by optimizing the materials, methods, and its thickness. This review paper extensively provides a detailed literature survey on various non-biological VOC-sensing materials including metal oxides, polymers, composites, and other novel materials. Furthermore, this review provides the associated limitations of each material and a summary table comparing the performance of various sensing materials to give a better insight to the readers.

Standardization of Manual Method of Immunohistochemical Staining for Breast Cancer Biomarkers at Tertiary Cancer Care Center: An Audit.

Immunohistochemistry (IHC) is a necessary ancillary technique in surgical pathology laboratories, particularly for oncology tissue specimens. Automation in the IHC technique has an advantage over manual methods in terms of quality, except for the cost of the equipment. Thus, the manual method of IHC staining is the preferred method of choice in countries with limited resources. However, standardization of all steps in the preanalytic phase is critical to obtain reliable immunohistochemistry test results. The current audit was conducted to describe the preanalytic factors affecting manual IHC methods. The most important preanalytic factors were fixative, the composition of dehydrate, pH, drying of sections, and heat-mediated antigen retrieval method (HMAR). The domestic pressure cooker method was found to be the best for HMAR.

Optical Fiber, Nanomaterial, and THz-Metasurface-Mediated Nano-Biosensors: A Review.

The increasing use of nanomaterials and scalable, high-yield nanofabrication process are revolutionizing the development of novel biosensors. Over the past decades, researches on nanotechnology-mediated biosensing have been on the forefront due to their potential application in healthcare, pharmaceutical, cell diagnosis, drug delivery, and water and air quality monitoring. The advancement of nanoscale science relies on a better understanding of theory, manufacturing and fabrication practices, and the application specific methods. The topology and tunable properties of nanoparticles, a part of nanoscale science, can be changed by different manufacturing processes, which separate them from their bulk counterparts. In the recent past, different nanostructures, such as nanosphere, nanorods, nanofiber, core-shell nanoparticles, nanotubes, and thin films, have been exploited to enhance the detectability of labelled or label-free biological molecules with a high accuracy. Furthermore, these engineered-materials-associated transducing devices, e.g., optical waveguides and metasurface-based scattering media, widened the horizon of biosensors over a broad wavelength range from deep-ultraviolet to far-infrared. This review provides a comprehensive overview of the major scientific achievements in nano-biosensors based on optical fiber, nanomaterials and terahertz-domain metasurface-based refractometric, labelled and label-free nano-biosensors.

No-core fiber-based highly sensitive optical fiber pH sensor.

The present work describes the fabrication and characterization of an optical fiber pH sensor using a sol­gel technique. The sensing head configuration is incorporated using a short section of no-core fiber, coated with tetraethyl orthosilicate and spliced at the end of a single mode fiber with a bulge. Different types of indicators (bromophenol blue, cresol red, and chlorophenol red) were used to achieve a wide pH range from 2 to 13. High sensitivities of the fabricated device were found to be 1.02 and ? 0.93 ?? nm / pH for acidic and alkaline solutions, respectively. From the characterization results, it was noted that there is an impact of ionic strength and an effect of the temperature of liquid on the response characteristic, which is an advantage of the existing device over the other pH sensors. The fabricated sensor exhibited good reflection spectrum, indicating a blueshift in resonance wavelength for alkaline solutions and a redshift for acidic solutions.

Signs of Fungal Infection in Dead Mimic the Chronic Torture.

The cases of battered woman syndrome (BWS) are very common in India. The majority of the women suffer battering by their family members especially in-laws. The injuries occurring each time indicate their being battered, but on being questioned about these happenings, a mismatched history being given by them is the major indication of BWS. In many of the cases, the injuries present over the body either in healing stages or in association with skin diseases may mislead the forensic pathologists and investigating agencies. One such rare autopsy was conducted where the healing lesions of the chronic fungal infections were mistaken as the injuries of chronic torture. The case is presented here to remind to the forensic pathologist about the possibility of the signs of chronic fungal infections in dead, which can mimic the torture, and to discuss its medicolegal implications.