Insight of Employing Molecular Junctions for Sensor Applications.

Molecular junctions (MJs) exhibit distinct charge transport properties and have the potential to become the next generation of electronic devices. Advancing molecular electronics for practical uses, such as sensors, is crucial to propel its progress to the next level. In this review, we discussed how MJs can serve as a sensor for detecting a wide range of analytes with exceptional sensitivity and specificity.

3D nanoplasmonic structure for ultrahigh enhanced SERS with less variability, polarization independence, and multimodal sensing applied to picric acid detection.

Surface-enhanced Raman scattering (SERS) is recognized as a powerful analytical method. However, its efficacy is hindered by considerable signal variability stemming from factors like surface irregularities, temporal instability of the substrate, interference with substrate signal, polarization sensitivity and uneven molecular distribution. To address these challenges, a new strategy is employed to enhance the reproducibility of SERS signals.

Identification of spermatogenesis in individual seminiferous tubules and testicular tissue of adult normal and busulfan-treated mice employing Raman spectroscopy and principal component analysis.

The present study aims to identify spermatogenesis in testicular seminiferous tubules (ST) and testicular tissue of adult normal and busulfan-treated mice utilizing PCA and Raman spectroscopy. Raman measurements were conducted on single tubules and testes samples from adult and immature mice, comparing them with those from busulfan-treated adult mice, with validation through histological examination. The analysis revealed a higher signal variability (30 %-40 % at the peaks), prompting scrutiny of individual Raman spectra as a means of spermatogenesis measurement.

Precise detection of trace level protein using MIP-MoS nanocomposite functionalized PCF based interferometer.

Fiber optic interferometry combined with recognizing elements has attracted intensive attention for the development of different biosensors due to its superior characteristic features. However, the immobilization of sensing elements alone is not capable of low-concentration detection due to weak interaction with the evanescent field of the sensing transducer. The utilization of different 2D materials with high absorption potential and specific surface area can enhance the intensity of the evanescent field and hence the sensitivity of the sensor.

Label-Free Biochemical Sensing Using Processed Optical Fiber Interferometry: A Review.

Over the last 20 years, optical fiber-based devices have been exploited extensively in the field of biochemical sensing, with applications in many specific areas such as the food processing industry, environmental monitoring, health diagnosis, bioengineering, disease diagnosis, and the drug industry due to their compact, label-free, and highly sensitive detection. The selective and accurate detection of biochemicals is an essential part of biosensing devices, which is to be done through effective functionalization of highly specific recognition agents, such as enzymes, DNA, receptors, etc., over the transducing surface.

Real-Time Ellipsometric Surface Plasmon Resonance Sensor Using Polarization Camera May Provide the Ultimate Detection Limit.

Ellipsometric Surface Plasmon Resonance (SPR) sensors are known for their relatively simple optical configuration compared to interferometric and optical heterodyne phase interrogation techniques. However, most of the previously explored ellipsometric SPR sensors based on intensity measurements are limited by their real-time applications because phase or polarization shifts are conducted serially. Here we present an ellipsometric SPR sensor based on a Kretschmann-Raether (KR) diverging beam configuration and a pixelated microgrid polarization camera.

Detection of necrotrophic DNA marker of anthracnose causing Colletotrichum gloeosporioides fungi in harvested produce using surface plasmon resonance.

Agriculture and food crops monitoring is extremely important for securing the food supply chain to human society. Here, we developed a highly specific detection method for monitoring pathogenic fungus Colletotrichum gloeosporioides using necrotrophic DNA biomarker as the recognition element and surface plasmon resonance (SPR) as transducing mechanism in the prism coupling configuration. The sensor shows its response for a wide range of concentrations from pM to μM of target DNA sequence using a complementary DNA probe immobilized on the sensor surface, which could detect concentrations as low as 7 pM.

A comprehensive review on plasmonic-based biosensors used in viral diagnostics.

The proliferation and transmission of viruses has become a threat to worldwide biosecurity, as exemplified by the current COVID-19 pandemic. Early diagnosis of viral infection and disease control have always been critical. Virus detection can be achieved based on various plasmonic phenomena, including propagating surface plasmon resonance (SPR), localized SPR, surface-enhanced Raman scattering, surface-enhanced fluorescence and surface-enhanced infrared absorption spectroscopy.

Microstructured optical fiber based Fabry-Pérot interferometer as a humidity sensor utilizing chitosan polymeric matrix for breath monitoring.

This study reports a method for humidity sensing based on a specialty microstructured optical fiber (MOF). A suspended tri-core MOF was fabricated using the stack and draw technique. A low finesse sensing head was prepared by depositing a chitosan polymer matrix within the holes of the MOF, forming a Fabry-Pérot interferometer as a sensing platform while the chitosan film acts as the sensing material.

Hypersensitive and selective biosensing based on microfiber interferometry and molecular imprinted nanoparticles.

The molecular imprinting techniques with interferometric platform are promising for next-generation optical sensors for online and remote biosensing and device applications. This technique has shown a tremendous potential to provide a highly specific detection of target analyte/molecule with artificial complementary scaffolds in the polymeric nanostructures relay with tunable aspect ratio, low cost synthesis procedure and applicability in harsh environment. To date, no molecular imprinted nanoparticles has been integrated with optical microwire platform in the literature.

Ion-imprinted nanoparticles for the concurrent estimation of Pb(II) and Cu(II) ions over a two channel surface plasmon resonance-based fiber optic platform.

We report the design, fabrication, and characterization of an optical fiber sensor based on the surface plasmon resonance (SPR) technique for the simultaneous determination of lead (Pb) and copper (Cu) metal ions in aqueous samples. Two cascade channels over a single optical fiber are fabricated by removing cladding from two well-separated regions of the fiber. SPR working as a transducing mechanism for the sensor is realized by coating thin films of copper and silver over unclad cores of channel I and channel II, respectively.

Surface plasmon resonance based fiber optic trichloroacetic acid sensor utilizing layer of silver nanoparticles and chitosan doped hydrogel.

In this study, we report a silver nanoparticles/chitosan doped hydrogel-based fiber optic sensor for the detection of trichloroacetic acid (TCA). The sensor is based on the combined phenomenon of localized and propagating surface plasmons. The sensing relies on the interaction of TCA with silver nanoparticles (AgNP) which results in the electron transfer between the negative group of TCA and positive amino group of AgNP stabilizer (chitosan).

Highly sensitive and selective erythromycin nanosensor employing fiber optic SPR/ERY imprinted nanostructure: Application in milk and honey.

An erythromycin (ERY) detection method is proposed using the fiber optic core decorated with the coatings of silver and an over layer of ERY imprinted nanoparticles. Synthesis of ERY imprinted nanoparticles is carried out using miniemulsion method. The operating range of the sensor is observed to be from 1.

Surface Plasmon Resonance-Based Fiber Optic Sensors Utilizing Molecular Imprinting.

Molecular imprinting is earning worldwide attention from researchers in the field of sensing and diagnostic applications, due to its properties of inevitable specific affinity for the template molecule. The fabrication of complementary template imprints allows this technique to achieve high selectivity for the analyte to be sensed. Sensors incorporating this technique along with surface plasmon or localized surface plasmon resonance (SPR/LSPR) provide highly sensitive real time detection with quick response times.

A contemporary approach for design and characterization of fiber-optic-cortisol sensor tailoring LMR and ZnO/PPY molecularly imprinted film.

A fiber optic salivary cortisol sensor using a contemporary approach of lossy mode resonance and molecular imprinting of nanocomposites of zinc oxide (ZnO) and polypyrrole (PPY) is structured and depicted for the concentration range of 0-10g/ml of cortisol prepared in artificial saliva. Components of polymer preparation and the nanocomposite of polymer with ZnO are optimized for realizing the molecular imprinted layer of the sensor. Nanocomposite having 20% of ZnO in PPY is found to give highest sensitivity of the sensor.

A localized and propagating SPR, and molecular imprinting based fiber-optic ascorbic acid sensor using an in situ polymerized polyaniline-Ag nanocomposite.

We report a successful approach for the fabrication and characterization of a fiber-optic sensor for ascorbic acid (AA) detection, using a molecularly imprinted polyaniline-Ag (PANI-Ag) nanocomposite layer based on the combined phenomena of surface plasmon resonance (SPR) and localized SPR (LSPR). The PANI-Ag nanocomposite is synthesized by an in situ polymerization process and AA imprints are prepared on the polymeric composite. The confirmation of the PANI-Ag nanocomposite and AA imprinting is performed using various characterization methods such as x-ray diffraction (XRD), UV-vis, Fourier transform infrared spectroscopy and scanning electron microscopy.

FO-SPR based dextrose sensor using Ag/ZnO nanorods/GOx for insulinoma detection.

In this piece of work, a fiber optic sensor has been fabricated and characterized using surface plasmon resonance for dextrose sensing. The concentration range used in this study is for diagnosing the cases of hypoglycaemia especially in suppression tests of insulinoma. Insulinoma is a medical case in which the person is recognized being hypoglycaemic with the blood dextrose level falling down to 2.

Fiber optic profenofos sensor based on surface plasmon resonance technique and molecular imprinting.

A successful approach for the fabrication and characterization of an optical fiber sensor for the detection of profenofos based on surface plasmon resonance (SPR) and molecular imprinting is introduced. Molecular imprinting technology is used for the creation of three dimensional binding sites having complementary shape and size of the specific template molecule over a polymer for the recognition of the same. Binding of template molecule with molecularly imprinted polymer (MIP) layer results in the change in the dielectric nature of the sensing surface (polymer) and is identified by SPR technique.