Optical Biosensors and Their Applications for the Detection of Water Pollutants

Abstract

The correct detection and quantification of pollutants in water is key to regulating their presence in the environment. Biosensors offer several advantages, such as minimal sample preparation, short measurement times, high specificity and sensibility and low detection limits. The purpose of this review is to explore the different types of optical biosensors, focusing on their biological elements and their principle of operation, as well as recent applications in the detection of pollutants in water. According to our literature review, 33% of the publications used fluorescence-based biosensors, followed by surface plasmon resonance (SPR) with 28%. So far, SPR biosensors have achieved the best results in terms of detection limits. Although less common (22%), interferometers and resonators (4%) are also highly promising due to the low detection limits that can be reached using these techniques. In terms of biological recognition elements, 43% of the published works focused on antibodies due to their high affinity and stability, although they could be replaced with molecularly imprinted polymers. This review offers a unique compilation of the most recent work in the specific area of optical biosensing for water monitoring, focusing on both the biological element and the transducer used, as well as the type of target contaminant. Recent technological advances are discussed.

Extremozyme-Based Biosensors for Environmental Pollution Monitoring: Recent Developments

“…The configuration, performances, and applications of enzyme-based biosensors were discussed in several recent reviews [ 6 , 8 , 78 , 79 , 80 , 81 , 82 , 83 , 84 , 85 , 86 , 87 , 88 , 89 ]. Both the direct catalytic activity and the inhibition of enzymatic activity were exploited in these applications [ 6 , 8 , 76 , 90 ].…”

Recent Progresses in Optical Biosensors for Interleukin 6 Detection

“…Among all types of optical biosensors, the most common, predominant, and extensively used technique is the surface plasmon resonance (SPR) optical biosensors, due to high sensitivity, robustness, cost-effectiveness, multiplexing, and diversity [ 40 ]. SPR is a phenomenon which occurs when the free electrons in the metal surface layer are excited by photons of incident light at a specific angle, causing an evanescent wave [ 41 ]. This causes the production of surface plasmons and thus reduces the intensity of the reflected light at a specific angle called the resonance angle [ 39 ].…”

“…This causes the production of surface plasmons and thus reduces the intensity of the reflected light at a specific angle called the resonance angle [ 39 ]. This phenomenon is beneficial for monitoring changes in refractive index, because the evanescent wave is very sensitive to changes in the vicinity of the surface [ 41 ]. SPR occurs only at the nanometer scale in metals (gold and silver are preferred) and are classified into two categories: Localized Surface Plasmon Resonance (LSPR), when the phenomenon occurs on sub-wavelength-sized metal nanoparticles, and SPR, when it happens on thin metallic films [ 42 ].…”

“…Considering the type of material, from a physical point of view, silver is seen to be better due to its more intense plasmon. However, gold is more used because of its chemically inert nature [ 41 ]. One of the methods benefiting from the characteristics of each material is the application of multilayer or core–shell nanoparticles [ 43 ].…”

Enhancing Evanescent Wave Coupling of Near-Surface Waveguides with Plasmonic Nanoparticles

“…To our knowledge, this is the first time that nanoparticles are used to enhance evanescent wave coupling from an fs-laser-inscribed surface waveguide. This is of great interest for robust and compact three-dimensional integrated photonic circuits for sensing applications such as greenhouse gases detection [26], water pollutants detection [27] and biosensors [28,29].…”