Optical Biosensors for Label-Free Detection of Small Molecules

Abstract

Label-free optical biosensors are an intriguing option for the analyses of many analytes, as they offer several advantages such as high sensitivity, direct and real-time measurement in addition to multiplexing capabilities. However, development of label-free optical biosensors for small molecules can be challenging as most of them are not naturally chromogenic or fluorescent, and in some cases, the sensor response is related to the size of the analyte. To overcome some of the limitations associated with the analysis of biologically, pharmacologically, or environmentally relevant compounds of low molecular weight, recent advances in the field have improved the detection of these analytes using outstanding methodology, instrumentation, recognition elements, or immobilization strategies. In this review, we aim to introduce some of the latest developments in the field of label-free optical biosensors with the focus on applications with novel innovations to overcome the challenges related to small molecule detection. Optical label-free methods with different transduction schemes, including evanescent wave and optical fiber sensors, surface plasmon resonance, surface-enhanced Raman spectroscopy, and interferometry, using various biorecognition elements, such as antibodies, aptamers, enzymes, and bioinspired molecularly imprinted polymers, are reviewed.

Critical assessment of relevant methods in the field of biosensors with direct optical detection based on fibers and waveguides using plasmonic, resonance, and interference effects

“…Plasmon-enhanced optical sensors are discussed in comparison with surface-enhanced Raman approaches [409]. Similar discussions with added interferometry can be found in [114]. More general reviews deal with SPR, interferometers, waveguide-based sensors, ring resonators, photonic crystals, and Bragg gratings [111].…”

“…Progress in material fabrication and novel substrate with enhanced optical response properties and potential application for rapid analytical measurement of target interactions from proteins to DNA and viruses are demonstrated in a review article on emerging applications [113]. Looking especially at small molecules, many techniques, including surfaceenhanced Raman spectroscopy, have been reviewed in a recent article, together with potential evaluation techniques [114]. Raman and especially using the SERS (surfaceenhanced Raman spectroscopy) instrumentation has become very interesting because of new developments resulting in easy to use and at low costs [115].…”

Recent Progress in Optical Sensors for Biomedical Diagnostics

“…Optical detection is more common than electrochemical or piezoelectric techniques and it is performed by harnessing the optical field with a moiety capable of biorecognition [1,3]. Optical sensors can be classified on the basis of their detection modes (label-based or label-free), recognition mechanism or the optical phenomenon exploited for sensing [5]. Although the introduction of a label is an additional step, any desired wavelength can be used for the analysis in label-based sensors [6,7].…”

“…In case of catalytic optical sensors, biochemical species are recognised and converted into products via a chemical reaction by the biocomponent. Affinity-based sensors make use of the specific abilities of the receptor to bind with the analyte [3,5,6]. Based on the phenomenon exploited for sensing the receptor-analyte interactions, Figure 1 shows the different varieties of sensors used for health care diagnosis.Micromachines 2020, 11, x FOR PEER REVIEW 2 of 31 affinity-based sensors.…”

Human elastin‐like polypeptides as a versatile platform for exploitation of ultrasensitive bilirubin detection by UnaG

“…(Kumagai et al, 2013). We speculated that UnaG might be an interesting functional domain to realize three-dimensional (3D) matrices for the reagentless ultrasensitive detection of bilirubin in complex biological fluids, enabling the establishment of new detection systems for lab and field-based applications (Peltomaa, Glahn-Martínez, Benito-Peña, & Moreno-Bondi, 2018).…”