Advances in Optical Sensors for Persistent Organic Pollutant Environmental Monitoring

Abstract

Optical chemical sensors are widely applied in many fields of modern analytical practice, due to their simplicity in preparation and signal acquisition, low costs, and fast response time. Moreover, the construction of most modern optical sensors requires neither wire connections with the detector nor sophisticated and energy-consuming hardware, enabling wireless sensor development for a fast, in-field and online analysis. In this review, the last five years of progress (from 2017 to 2021) in the field of optical chemical sensors development for persistent organic pollutants (POPs) is provided. The operating mechanisms, the transduction principles and the types of sensing materials employed in single selective optical sensors and in multisensory systems are reviewed. The selected examples of optical sensors applications are reported to demonstrate the benefits and drawbacks of optical chemical sensor use for POPs assessment.

Recent advances in the analysis of polycyclic aromatic hydrocarbons in food and water

“…SERS is emerging as a popular analytical technique for quantitative determination of PAHs in different matrices. The mechanism of detection involves extremely high enhancement of weak intrinsic Raman signals by plasmonic nanostructures such as gold and silver through generation of surface plasmon resonance from localized electromagnetic fields [ 89 ]. Such unique characteristics makes the SERS technique suitable for sensor development to attain an ultra-high sensitivity with tailored synthesis of metal nanostructures for a specific purpose as well as modification with multiple anchoring of ligands/functional groups enabling detection of different analytes with multiplexing capability [ 71 , 90 ].…”

“…Moreover, some novel SERS substrates with high enhancement factors have been reported such as gold on nickel 3D foam, gold on TiO 2 nanotube arrays, gold coffee-ring, gold on alginate gel and gold on porous polymer [ 71 , 92 ]. Despite the development of several SERS substrates so far, some notable shortcomings still persist in PAHs detection by SERS which include restricted application to a specific class/ number of PAHs, requirement of preconcentration step due to poor water solubility of PAHs, significant decrease in signal enhancement due to continuous laser irradiation and distortion of SERS signals of PAHs by those generated by functionalized molecules itself [ 89 ]. Table 6 summarizes the SERS-based optical sensors recently developed for detection of PAHs in food and water samples.…”

“…The 3D substrates in the form of metal–organic frameworks (MOFs) have attracted attention recently as a porous organic-inorganic material for encapsulation of metal nanoparticles to impart unique characteristics of high surface area, tunable pore size, easy functionalization and stability for attachment of an abundant amount of SERS active metal nanoparticles in the unique 3D configuration of MOFs [ 89 , 107 ]. Also, the MOFs can adsorb analytes making them in close proximity to hotspots created by metal nanoparticles, thereby facilitating the MOFs-based sensors to function without requiring a preconcentration step.…”

“…Incorporation of magnetic nanoparticles into SERS sensors for detection PAHs has been particularly attractive as MNPs can offer synergistic signal enhancement with plasmonic nanoparticles, improved sensitivity by enrichment of analytes and reuse by their adsorptive and magnetic properties as well as enabling conjugation with receptors including antibodies and aptamers for biosensing application [ 71 , 89 ]. Du et al [ 92 ] developed a versatile Fe 3 O 4 @Au SERS substrate for detection of 16 EPA priority PAHs by homogenously grafting AuNPs on Fe 3 O 4 microspheres.…”

Fluorescent sensing of non-steroidal anti-inflammatory drugs naproxen and ketoprofen by dansylated squaramide-based receptors

“…Thus, providing devices able to allow a rapid on-site detection of target analytes would have a dramatic impact on the environmental control with significant economic benefits. 7 The development of chemical sensors has been conceived to bypass restrictions related to classical analytical protocols and use of conventional laboratory tech-niques for environmental control. While the technologic foundation for chemical sensors already exists, their application to EPs detection is complicated by the difficulty in the design of selective receptors due to the large number and diversity of listed EPs.…”