Progress of Optical Biosensors for Analysis of Pathogens and Organic Pollutants in Water since 2015

Water contamination by pathogens and organic pollutants is one of the major environmental problems that risk human health. Climate change with extreme weather can promote their prevalence in waters. Environmental monitoring of these pollutants in a fast, continuous, and accurate manner is of increasing demand, especially under the climate change context, but is challenged by their ubiquity and trace concentrations. Optical biosensing is one of the desired solutions owing to its rapid and accurate detection with high sensitivity. Principally, an optical biosensor recognizes these bioactive toxins and contaminants by tailored bioreceptors (e.g., aptamer, enzyme, and cells) and transduces the biological response to optical signals. Research efforts have been made on tailoring bioreceptors and enhancing signal transducing by nanoparticles. This study comprehensively reviewed the mechanisms of optical biosensing and the recent development of bioreceptors and nanomaterials on the enhancement for the rapid, easy, and accurate analysis of emerging contaminants in water. The advantages and challenges on sensitivity, selectivity, and durability of biosensors were discussed along with the opportunities and development strategies.

Passivated Porous Silicon Membranes and Their Application to Optical Biosensing

A robust fabrication method for stable mesoporous silicon membranes using standard microfabrication techniques is presented. The porous silicon membranes were passivated through the atomic layer deposition of different metal oxides, namely aluminium oxide Al2O3, hafnium oxide HfO2 and titanium oxide TiO2. The fabricated membranes were characterized in terms of morphology, optical properties and chemical properties. Stability tests and optical probing noise level determination were also performed. Preliminary results using an Al2O3 passivated membranes for a biosensing application are also presented for selective optical detection of Bacillus Cereus bacterial lysate. The biosensor was able to detect the bacterial lysate, with an initial bacteria concentration of 106 colony forming units per mL (CFU/mL), in less than 10 min.

Application of Tamm Plasmon Polaritons and Cavity Modes for Biosensing in the Combined Spectroscopic Ellipsometry and Quartz Crystal Microbalance Method

Low-cost 1D plasmonic photonic structures supporting Tamm plasmon polaritons and cavity modes were employed for optical signal enhancement, modifying the commercially available quartz crystal microbalance with dissipation (QCM-D) sensor chip in a combinatorial spectroscopic ellipsometry and quartz microbalance method. The Tamm plasmon optical state and cavity mode (CM) for the modified mQCM-D sample obtained sensitivity of ellipsometric parameters to RIU of ΨTPP = 126.78 RIU−1 and ΔTPP = 325 RIU−1, and ΨCM = 264 RIU−1 and ΔCM = 645 RIU‑1, respectively. This study shows that Tamm plasmon and cavity modes exhibit about 23 and 49 times better performance of ellipsometric parameters, respectively, for refractive index sensing than standard spectroscopic ellipsometry on a QCM-D sensor chip. It should be noted that for the optical biosensing signal readout, the sensitivity of Tamm plasmon polaritons and cavity modes are comparable with and higher than the standard QCM-D sensor chip. The different origin of Tamm plasmon polaritons (TPP) and cavity mode (CM) provides further advances and can determine whether the surface (TPP) or bulk process (CM) is dominating. The dispersion relation feature of TPP, namely the direct excitation without an additional coupler, allows the possibility to enhance the optical signal on the sensing surface. To the best of our knowledge, this is the first study and application of the TPP and CM in the combinatorial SE-QCM-D method for the enhanced readout of ellipsometric parameters.

Carbon dots for virus detection and therapy

Recent experience with the COVID-19 pandemic should be a lesson learnt with respect to the effort we have to invest in the development of new strategies for the treatment of viral diseases, along with their cheap, easy, sensitive, and selective detection. Since we live in a globalized world where just hours can play a crucial role in the spread of a virus, its detection must be as quick as possible. Thanks to their chemical stability, photostability, and superior biocompatibility, carbon dots are a kind of nanomaterial showing great potential in both the detection of various virus strains and a broad-spectrum antiviral therapy. The biosensing and antiviral properties of carbon dots can be tuned by the selection of synthesis precursors as well as by easy post-synthetic functionalization. In this review, we will first summarize current options of virus detection utilizing carbon dots by either electrochemical or optical biosensing approaches. Secondly, we will cover and share the up-to-date knowledge of carbon dots’ antiviral properties, which showed promising activity against various types of viruses including SARS-CoV-2. The mechanisms of their antiviral actions will be further adressed as well. Finally, we will discuss the advantages and distadvantages of the use of carbon dots in the tangled battle against viral infections in order to provide valuable informations for further research and development of new virus biosensors and antiviral therapeutics. Graphical abstract

Optical Biosensors for Diagnostics of Infectious Viral Disease: A Recent Update

The design and development of biosensors, analytical devices used to detect various analytes in different matrices, has emerged. Biosensors indicate a biorecognition element with a physicochemical analyzer or detector, i.e., a transducer. In the present scenario, various types of biosensors have been deployed in healthcare and clinical research, for instance, biosensors for blood glucose monitoring. Pathogenic microbes are contributing mediators of numerous infectious diseases that are becoming extremely serious worldwide. The recent outbreak of COVID-19 is one of the most recent examples of such communal and deadly diseases. In efforts to work towards the efficacious treatment of pathogenic viral contagions, a fast and precise detection method is of the utmost importance in biomedical and healthcare sectors for early diagnostics and timely countermeasures. Among various available sensor systems, optical biosensors offer easy-to-use, fast, portable, handy, multiplexed, direct, real-time, and inexpensive diagnosis with the added advantages of specificity and sensitivity. Many progressive concepts and extremely multidisciplinary approaches, including microelectronics, microelectromechanical systems (MEMSs), nanotechnologies, molecular biology, and biotechnology with chemistry, are used to operate optical biosensors. A portable and handheld optical biosensing device would provide fast and reliable results for the identification and quantitation of pathogenic virus particles in each sample. In the modern day, the integration of intelligent nanomaterials in the developed devices provides much more sensitive and highly advanced sensors that may produce the results in no time and eventually help clinicians and doctors enormously. This review accentuates the existing challenges engaged in converting laboratory research to real-world device applications and optical diagnostics methods for virus infections. The review’s background and progress are expected to be insightful to the researchers in the sensor field and facilitate the design and fabrication of optical sensors for life-threatening viruses with broader applicability to any desired pathogens.