Biosensors for Security and Bioterrorism: Definitions, History, Types of Agents, New Trends and Applications

There has recently been concern about confidence intervals calculated using the standard error of parameter estimates from NONMEM, a computer program that uses a non-linear mixed-effects model to calculate relative bioavailability (F), because of possible downward bias of these estimates. In this study an alternate approach, the log-likelihood procedure, was used to calculate the confidence intervals for F from NONMEM. These were then compared with those calculated using the standard error of the parameter estimates, the traditional NONMEM approach, and the standard model-independent method, to determine whether bias exists. By use of data from a single dose, open cross-over study of ibuprofen using 14 healthy male volunteers, NONMEM was shown to give results consistent with those obtained using the standard model-independent method of analysis and could be a useful tool in the determination of F where conditions for using the standard method of analysis are not optimum. The width of the confidence interval for F using the log-likelihood procedure was narrower and non-symmetrical when compared with that obtained using the traditional NONMEM approach. The width of the confidence interval obtained using the traditional NONMEM method was similar to that from the standard approach, however the parameter estimate for F was higher than that obtained from the standard method. This could have been because of an outlier in the data set to which the standard approach is more sensitive. No downward bias was found in the confidence intervals from NONMEM. The bioavailability data set was of relatively low variability and more research with highly variable data is necessary before it can be concluded that the confidence intervals calculated from NONMEM can be used for hypothesis testing.

In this novel work the EMI shielding properties of low density, low cost and less explored carbon nano fiber (CNF) nanofiller embedded in the epoxy matrix is investigated for its potential use in electromagnetic interference (EMI) shielding of sensitive electronic equipment's applied in industrial, military applications and also in protection of human health. The CNF nanocomposite with filler concentrations 1, 5, 10 and 15 wt.% epoxy are synthesized via ultrasonication method. The EMI shielding efficiency of all the nanocomposites prepared are investigated in the X-band using VNA and the result shows that nanocomposite with CNF as 15 wt. % of epoxy achieved maximum EMI shielding efficiency of 35.53 dB in X-band at 2 mm thickness. Hence this lightweight CNF based nanocomposite can be potentially applied in many application such as military, industrial and civil application, where high shielding efficiency is required.

PCR assays were compared with standard microbiological methods for rapid detection of the United States Pharmacopoeia (USP) bacterial indicators in artificially contaminated samples of raw materials and cosmetic/pharmaceutical products. DNA primers containing the specific sequences of the uidA gene of the β-glucuronidase enzyme for Escherichia coli, the membrane lipoprotein gene oprL for Pseudomonas aeruginosa, and the 16S ribosomal gene for Staphylococcus aureus were used for detection in the PCR reaction. Contaminated samples were incubated for 24 h at 35°C. After incubation in broth media with and without 4% Tween 20, samples were streaked on selective growth media. After 5–6 days, all microbial indicators were morphologically and biochemically identified using standard methods while detection and identification by the PCR-based assays was completed within 27–30 h. Rapid PCR detection of E. coli, S. aureus, and P. aeruginosa will allow a faster quality evaluation and release of raw materials and cosmetic/pharmaceutical products sensitive to microbial contamination.

Salmonella is a common and important pathogen for both human and animals. All Salmonella except Salmonella pullorum and Salmonella gallinarum have flagellum. Flagellin (FliC) is the main subunit protein forming the bacterial filament, which is present in large amounts on the surface of all flagellated Salmonella. After bioinformatics analysis, the most highly conserved region (locates position from 1 to 102 amino acid residue of FliC, we named it as FliC′) was selected, and corresponding recombinant FliC′ (rFliC′) protein was tailored as an immunogen to generate monoclonal antibodies (MAbs) against Salmonella flagellin. BALB/c mice were immunized with the purified recombinant protein rFliC′, which were prepared by prokaryotic expression system pET22b (+) expressing FliC′. After fusion of spleen cells from the immunized mice and SP2/0 cells, three hybridoma cells (1D6, 2G6 and 3E2) producing MAbs against targeted flagellate Salmonella FliC′ were generated and screened. The ability of MAb 3E2 to recognize and bind to Salmonella flagella was demonstrated by immunogold electron microscopy (IEM) method. Western blot (WB) analysis demonstrated that MAb 3E2 could specifically recognize flagellated Salmonella strains. Moreover, MAb 3E2 has a direct agglutination activity against Salmonella strains with visible agglutination reaction. To further verify this agglutination activity, a total of 52 flagellated Salmonella strains (23 serovars), 8 non-flagellate Salmonella strains (2 serovars) and 16 other non-Salmonella bacteria strains were used to evaluate the specificity of the MAb by direct Slide Agglutination Test (SAT). Results showed that MAb 3E2 reacted with all Salmonella strains possessing flagellum and had no cross-reaction with non-flagellate Salmonella strains or other non-Salmonella bacteria strains. Sequentially, the ability to detect the presence of Salmonella in raw samples of the MAb 3E2-based SAT method was evaluated. The conventional culture-based detection method was performed as the standard reference method for detection of Salmonella. Altogether, 369 samples collected from laying hens were tested, and the results indicated that the MAb 3E2-based SAT method could specifically detect Salmonella. Furthermore, the SAT results were obtained more quickly, as compared with the standard method. As a whole, the MAbs against the tailored conserved region of Salmonella flagellin were prepared in this study, and MAb 3E2-based SAT is a promising candidate for the flagellated Salmonella spp. rapid detection.

IEC 61000-4-30 has recently defined a method for detection and analysis of rapid voltage changes in power system networks. This paper presents some of the results obtained in the application of the IEC standard method in different low-voltage and medium-voltage power system networks with different load types and some of the limitations found in the standard method for the correct detection and characterization of these voltage events.

Frequency‐selective rasorber (FSR) can realize a passband between two adjacent absorption bands, which is essential in many electromagnetic scenarios such as antennas and cloaking technologies. However, the current printed circuit board (PCB)–based FSR has shortcomings such as being heavy, rigid, and complex structure (too many lumped elements), making it a long distance from practical military and civil applications. Here, a novel FSR comprised of carbon cloth/ copper cloth/ fabric hybrid structure is proposed to realize the function of frequency selective absorption for the application of indoor electromagnetic protection. Several sub‐subjects are studied, including the structure design of rasorber without lumped elements, the carbon cloth‐based planner resistive material, and the fabrication method of large area non‐contact patterns. Measured results show that a transmission window is achieved between two absorption bands with a transmission rate higher than 86%. Under the circumstances of similar electromagnetic properties, the sample has the unique features of simple structure, large area, high flexibility, and light‐weight compared with commonly used PCB technology, which largely improve the usability of FSR in practical civil or military applications.

A review of current advances in the detection of organophosphorus chemical warfare agents based biosensor approaches

Nerve agents such as Sarin, Soman, and Tabun are among the most lethal chemical warfare agents, classified as mass destruction agents due to their extreme toxicity and rapid disruption of the nervous system. These highly volatile and easily dispersible compounds can be deployed in warfare or acts of terrorism, causing fatal respiratory failure, seizures, and irreversible nerve damage even at minimal exposure. The urgency of detecting these agents with high precision is critical for global security and counterterrorism efforts. To address this challenge, a highly sensitive photonic crystal fiber (PCF) sensor with an elliptical cladding and circular core (E-PCF) is designed for the rapid and accurate detection of nerve agents in the terahertz (THz) spectrum. The sensor employs circular air holes in the vestibule region to enhance light-matter interaction, optimizing detection through key performance metrics such as relative sensitivity, effective material loss, and confinement loss. Using two materials, such as silica glass and Zeonex as background materials, the proposed sensor demonstrates exceptional sensitivity and minimal loss. Numerical analysis within the 1.6–3.6 THz range reveals outstanding performance for Sarin (99.6% relative sensitivity, 3 × 10⁻13 dB/m confinement loss), Soman (98.8% relative sensitivity, 1.1 × 10⁻¹² dB/m loss), and Tabun (98% relative sensitivity, 7.6 × 10⁻11 dB/m loss). With its exceptional optical properties, silica glass ensures highly reliable detection, making the proposed sensor a powerful tool for counterterrorism efforts, environmental monitoring, industrial hazard detection, and military defense. This innovative PCF-based sensing technology marks a major breakthrough in chemical warfare agent detection, providing a fast, precise, and efficient solution for identifying highly toxic substances that pose severe threats to public safety and national security.

Chromatographic analysis of chemical compounds related to the Chemical Weapons Convention

V-series nerve agents are very lethal to health and cause the inactivation of acetylcholinesterase which leads to neuromuscular paralysis and, finally, death. Therefore, rapid detection and elimination of V-series nerve agents are very important. Herein, we have carried out a theoretical investigation of carbon nitride quantum dots (C2N) as an electrochemical sensor for the detection of V-series nerve agents, including VX, VS, VE, VG, and VM. Adsorption of V-series nerve agents on C2N quantum dots is explored at M05-2X/6-31++G(d,p) level of theory. The level of theory chosen is quite adequate in systems describing non-bonding interactions. The adsorption behavior of nerve agents is characterized by interaction energy, non-covalent interaction (NCI), Bader’s quantum theory of atoms in molecules (QTAIM), frontier molecular orbital (FMO), electron density difference (EDD), and charge transfer analysis. The computed adsorption energies of the studied complexes are in the range of −12.93 to −17.81 kcal/mol, which indicates the nerve agents are physiosorbed onto C2N surface through non-covalent interactions. The non-covalent interactions between V-series and C2N are confirmed through NCI and QTAIM analysis. EDD analysis is carried out to understand electron density shifting, which is further validated by natural bond orbital (NBO) analysis. FMO analysis is used to estimate the changes in energy gap of C2N on complexation through HOMO-LUMO energies. These findings suggest that C2N surface is highly selective toward VX, and it might be a promising candidate for the detection of V-series nerve agents.

Accurate real-time methods for the detection of pathogenic microorganisms in the agri-food industry would represent an improvement over standard methods of analysis. We are currently developing a non-contact, scanning optical system for the detection of bacteria on meat surfaces based on fluorescence lifetime and intensity measurements. The system detects autofluorescent light emitted by the naturally occurring fluorophores in bacteria. Potential expected advantages of this system include accurate and efficient 2D real-time mapping of bacterial contamination of surfaces, and elimination of sample-to-sample cross-contamination. Furthermore, as the technique only requires minimal sample preparation and handling, the chemical properties of the specimen are preserved. This article presents the preliminary results obtained from a time-resolved fluorescence imaging system for the characterization of a non-pathogenic gram-negative bacteria, <i>Pseudomonas fluorescens</i>. Additionally we present a particular application of the system of interest to the agri-food industry, demonstrating its potential as a real-time macroscopic imaging system for mapping bacterial contamination on meat surfaces. Initial results indicate that the combination of fluorescence lifetime and intensity measurements provides a means for characterizing biological media and for detecting microorganisms on surfaces.

Amatoxin-containing mushroom poisonings are recorded worldwide and the frequency increases due to confusion with other macrofungi. Affected regions are characterized by important disparities in relation to available technological equipment for analytical identification of amatoxins. In this context the present study was designed to define advantages and disadvantages of the most accessible standard analytical methods for amatoxin detection. Several methods were compared: (1) a commercialized immunoassay kit, (2) standard high-performance liquid chromatography (HPLC) and (3) high-performance thin layer chromatography (HP-TLC). For each method, linearity, limit of detection (LOD), limit of quantification (LOQ) and recovery were determined. Six macrofungi were analysed using these compared methods, three known to contain amatoxins: Amanita phalloides, Amanita virosa, Lepiota josserandii, and three free-amatoxin containing macrofungi: Amanita muscaria, Macrolepiota procera and Omphalotus olearius. Our results will allow for a choice of method with full knowledge of advantages and disadvantages of each technique as a function of local technological possibilities when facing suspected poisoning due to amatoxin-containing mushrooms. The final aim is to be able to reach faster and effective diagnosis in order to save a patient's life.

Medical countermeasures to WMDs: Defence research for civilian and military use

Rapid and robust sensing of nerve agent (NA) threats is necessary for real-time field detection to facilitate timely countermeasures. Unlike conventional phosphotriesterases employed for biocatalytic NA detection, this work describes the use of a new, green, thermally stable, and biocompatible zirconium metal-organic framework (Zr-MOF) catalyst, MIP-202(Zr). The biomimetic Zr-MOF-based catalytic NA recognition layer was coupled with a solid-contact fluoride ion-selective electrode (F-ISE) transducer, for potentiometric detection of diisopropylfluorophosphate (DFP), a F-containing G-type NA simulant. Catalytic DFP degradation by MIP-202(Zr) was evaluated and compared to the established UiO-66-NH2 catalyst. The efficient catalytic DFP degradation with MIP-202(Zr) at near-neutral pH was validated by 31P NMR and FT-IR spectroscopy and potentiometric F-ISE and pH-ISE measurements. Activation of MIP-202(Zr) using Soxhlet extraction improved the DFP conversion rate and afforded a 2.64-fold improvement in total percent conversion over UiO-66-NH2. The exceptional thermal and storage stability of the MIP-202/F-ISE sensor paves the way toward remote/wearable field detection of G-type NAs in real-world environments. Overall, the green, sustainable, highly scalable, and biocompatible nature of MIP-202(Zr) suggests the unexploited scope of such MOF catalysts for on-body sensing applications toward rapid on-site detection and detoxification of NA threats.

This study deals with the rapid detection and differentiation of Escherichia coli, Salmonella, and Campylobacter, which are the most commonly identified commensal and pathogenic bacteria in foods, using fluorescence spectroscopy and multivariate analysis. Each bacterial sample cultured under controlled conditions was diluted in physiologic saline for analysis. Fluorescence spectra were collected over a range of 200-700 nm with 0.5 nm intervals on the PerkinElmer Fluorescence Spectrometer. The synchronous scan technique was employed to find the optimum excitation (lambda(ex)) and emission (lambda(em)) wavelengths for individual bacteria with the wavelength interval (Deltalambda) being varied from 10 to 200 nm. The synchronous spectra and two-dimensional plots showed two maximum lambda(ex) values at 225 nm and 280 nm and one maximum lambda(em) at 335-345 nm (lambda(em) = lambda(ex) + Deltalambda), which correspond to the lambda(ex) = 225 nm, Deltalambda = 110-120 nm, and lambda(ex) = 280 nm, Deltalambda = 60-65 nm. For all three bacterial genera, the same synchronous scan results were obtained. The emission spectra from the three bacteria groups were very similar, creating difficulty in classification. However, the application of principal component analysis (PCA) to the fluorescence spectra resulted in successful classification of the bacteria by their genus as well as determining their concentration. The detection limit was approximately 10(3)-10(4) cells/mL for each bacterial sample. These results demonstrated that fluorescence spectroscopy, when coupled with PCA processing, has the potential to detect and to classify bacterial pathogens in liquids. The methodology is rapid (>10 min), inexpensive, and requires minimal sample preparation compared to standard analytical methods for bacterial detection.