■ CONTENTS Books, Reviews, and Articles of General Interest 488 Sensors for (Dissolved) Gases and Vapors 489 Hydrogen 489 Hydrocarbons 490 Oxygen 491 Ammonia 493 Carbon Dioxide 494 Nitrogen Oxides 494 Vapors of Organic Solvents 495 Sensors for Humidity, Water Fractions, Hydrogen Peroxide, and Hydrazine 495 Humidity 495 Water Fractions 496 Hydrogen Peroxide and Hydrazine 496 Sensors for pH Values, Ions, and Salinity 496 pH Values 496 Ions 497 Salinity and Ionic Strength 499 Sensors for Organic Species 499 Biosensors 500 Immunosensors 500 PNA-Based Biosensors (DNA, Aptamers) 501 Other Affinity Sensors 501 Enzymatic Biosensors 502 Whole Cell Sensors 502 Advanced Optical Sensing Schemes and Materials 503 Author Information 505 Corresponding Author 505 Notes 505 Biographies 505 Acknowledgments 505 References 505

Fiber-Optic Chemical Sensors and Biosensors (2008–2012)

Pathogen and toxin-contaminated foods and beverages are a major source of illnesses, even death, and have a significant economic impact worldwide. Human health is always under a potential threat, including from biological warfare, due to these dangerous pathogens. The agricultural and food production chain consists of many steps such as harvesting, handling, processing, packaging, storage, distribution, preparation, and consumption. Each step is susceptible to threats of environmental contamination or failure to safeguard the processes. The production process can be controlled in the food and agricultural sector, where smart sensors can play a major role, ensuring greater food quality and safety by low cost, fast, reliable, and profitable methods of detection. Techniques for the detection of pathogens and toxins may vary in cost, size, and specificity, speed of response, sensitivity, and precision. Smart sensors can detect, analyse and quantify at molecular levels contents of different biological origin and ensure quality of foods against spiking with pesticides, fertilizers, dioxin, modified organisms, anti-nutrients, allergens, drugs and so on. This paper reviews different methodologies to detect pathogens and toxins in foods and beverages.

Detection Methodologies for Pathogen and Toxins: A Review

Etched multicore fiber sensor using copper oxide and gold nanoparticles decorated graphene oxide structure for cancer cells detection.

In this study, we report a chemical sensor utilizing localized surface plasmon resonance (LSPR) of gold nanoparticles (GNP) for vapour phase detection of explosives like 2,4,6-trinitrotoluene (TNT) and cyclotrimethylenetrinitramine (RDX). The GNP were immobilized on a U-bend fibre optic sensor probe of 200 μm core diameter and bend diameter of 1.5 mm for evanescent field based excitation of localized surface plasmons of the GNP. The immobilized GNP were functionalized with receptor molecules viz. 4-mercaptobenzoic acid (4-MBA), l -cysteine and cysteamine to provide the binding sites for the nitro-based explosive molecules. Binding of the explosive analytes to the surface moieties of the GNP was found to elicit refractive index changes in the environment surrounding the nanoparticles. This led to changes in the absorbance characteristics of the GNP-LSPR spectrum. Furthermore, the GNP coated probes modified with l -cysteine and cysteamine exhibited a high degree of selectivity towards TNT. The detection limit of the LSPR fibre optic probe for TNT vapours was found to be in the lower parts per billion (ppb) with further scope for improvement.

Pradeep Kumar Verma

Papers

Evanescent wave absorbance based fiber optic biosensor for label-free detection of E. coli at 280 nm wavelength.