Advanced Evanescent-Wave Optical Biosensors for the Detection of Nucleic Acids: An Analytic Perspective

Abstract

Evanescent-wave optical biosensors have become an attractive alternative for the screening of nucleic acids in the clinical context. They possess highly sensitive transducers able to perform detection of a wide range of nucleic acid-based biomarkers without the need of any label or marker. These optical biosensor platforms are very versatile, allowing the incorporation of an almost limitless range of biorecognition probes precisely and robustly adhered to the sensor surface by covalent surface chemistry approaches. In addition, their application can be further enhanced by their combination with different processes, thanks to their integration with complex and automated microfluidic systems, facilitating the development of multiplexed and user-friendly platforms. The objective of this work is to provide a comprehensive synopsis of cutting-edge analytical strategies based on these label-free optical biosensors able to deal with the drawbacks related to DNA and RNA detection, from single point mutations assays and epigenetic alterations, to bacterial infections. Several plasmonic and silicon photonic-based biosensors are described together with their most recent applications in this area. We also identify and analyse the main challenges faced when attempting to harness this technology and how several innovative approaches introduced in the last years manage those issues, including the use of new biorecognition probes, surface functionalization approaches, signal amplification and enhancement strategies, as well as, sophisticated microfluidic solutions.

Applications of Graphene Quantum Dots in Biomedical Sensors

“…Commonly, they bring together an emitting light source, a modulating element, a bio-receptor and a photo-detector for interpreting the optical response of a generated signal [11,82]. Optical transducers include fluorescence, photoluminescence (PL), chemiluminescence (CL), electrochemiluminescence (ECL), fluorescence resonance energy transfer (FRET) or Förster resonance energy transfer, interferometry, optical wavelength-modulated spectroscopy and surface plasmon resonance (SPR) [11,[82][83][84][85][86][87]. These techniques interpret optical signals that are highly sensitive to the refractive index variation in the proximity of bio-recognition events [86].…”

Silicon‐Based Integrated Label‐Free Optofluidic Biosensors: Latest Advances and Roadmap

“…For immobilization of nucleic acid probes in Figure 2c, the incorporation of reactive groups at the end of the nucleic acid sequence is required during the synthesis. [ 81,82 ]…”

“…The fundamental mode reveals a much weaker evanescent field for biointeraction compared to that of the first‐order mode. [ 82 ] As two modes reveal different n eff and phase velocity, the interference pattern at the output port changes when the bound analyte interacts with two modes. Capture and analysis of bacteria ( Bacillus cereus and Escherichia coli ) in ascitic fluids were first reported using BiMW biosensors in 2016 (see Figure 4c).…”

Bacteriophage Based Biosensors: Trends, Outcomes and Challenges

“…Optical biosensors are used as more suitable diagnostic systems for the detection of pathogens. Detection in optical biosensors is based on the variations induced in the light properties, such as refractive index, wavelength and polarization [42]. Currently, BIACORE 3000 biosensor and SPREETA biosensor as commercial optical biosensors are used for the detection of foodborne pathogens.…”

“…Salmonella enteritidis and E. coli O157:H7, and S. typhimurium and S. enteritidis, can be successfully detected by BIACORE 3000. and SPREETA biosensors, respectively [43]. Wavelengths-based biosensors enable real-time monitoring of biomolecular interactions by evaluating the kinetics and affinity of the interactions [42]. Planar optical waveguides contain an optically transparent guiding layer with a refractive index, which is higher than the substrate layers.…”