COVID-19, R U still there?

Background

COVID-19 has taught us to be more self-sufficient, patience, and more prepared for the next time when COVID-19’s family member would decide to come back to Earth and visit this beautiful creation again. Would like to learn more about COVID-19?

COVID-19 is the most recently discovered infectious disease caused by β (beta) coronavirus. It is a non-segmented positive-sense RNA virus. This new virus was unknown before the outbreak began in Wuhan, China, in December 2019.

Although no concrete evidence has been established yet, the coronavirus is primarily transmitted through inhalation. Infected patients may experience mild systems such as, a sore throat, headache, fever, dry cough, shortness of breath, and fatigue. However, in severe cases, viruses attack on the lungs causing pneumonia. Air sacs in lungs known as alveoli, exchange oxygen with blood and transported throughout the body, and when the coronavirus attaches to these alveoli cells, they begin to replicate within the cells. When the immune system attempts to destroy the viruses, the action results in the inflammatory response, and causes fluid accumulation in the lungs. As the lungs are filled with fluid, the body’s available oxygen decreases, which can lead to organ injury and death.

Normally, seven days is the incubation period of this infection. After seven days B lymphocyte of our immune system starts to produce IgM antibody. Production of IgM antibody reaches to the peak level after 10 days of infection, and eventually disappears after 30 days. Similarly, after 12 days of infection, our immune system starts to produce IgG antibody. Peak production of IgG antibody reaches after 20 days and may remain for a long time.

Reverse transcriptase real time PCR (RT-qPCR) and rapid antibody tests are major diagnostic tools, which are now in use universally. RT-qPCR is a gold standard method, that can detect viruses from the first day to up to 25 days of viral onset whereas, IgM rapid antibody test is useful after 10 days to 30 days of viral onset. Similarly, IgG rapid antibody test is useful after 25 days of viral onset.

Ultra-sensitive Sensors are not an Option, they are a Necessity 

Before, sensors were used to be just used for testing glucose level in humans, but now they have been developed to detect many dangerous diseases. As sensors have evolved, they now are needed more than ever with diseases such as many forms of cancer, and COVID 19 are prevalent. The problem is that there is a disconnect between what we need these sensors to do, and what they are currently capable of doing. That’s why we need ultra-sensitive sensors in order to detect diseases at the earliest stages because so many often get missed as a result of current detection limits. This is why we at Seed NanoTech, have come up with the concept of magnetoplasmonic sensor with sharp resonances, and high sensitivity and detection limits. Our approach is based on the combination of a specially designed metallic and ferromagnetic layers that are optimized to detect changes in the environment refractive index,  examined using magnetic activity in addition to the plasmonic and optical activities.

For more information, CLICK here.

Where magnetoplasmonics meets biology

Magneto-plasmonics is a relatively new field that has many great potential applications in biomedicine and biomedical technologies such as ultra-sensitive biosensing and bio-detection, bio-imaging, bio-therapy, drug-delivery, and nano-imaging, to name a few. A deep understanding of various factors influencing magnetoplasmon properties is an important step in the effort to design new magnetic sensors and devices. Although some progress on plasmonics has been achieved in the last few years, there is still a strong need to further investigate magneto-plasmonics, in order to better tune and control magneto-optic properties, as well as to increase the sensitivity of the magnetic bio-sensor through modification of the optical radiation, magnetic field, and structure.

This new field merges the physics of nano-magnetics, where biological samples such as cells and DNA are made to interact with magnetic moments of material in the transverse direction, and nano-optics, where biological samples are made to interact with optical radiation in visible, infra-red, and telecommunication wavelength ranges. In a similar manner, it merges nano-plasmonics where biological samples are made to interact with surface plasmonic wave fields, also referred to as evanescent radiation fields.

Magneto-optic-plasmonic Surface Plasmon Resonance

Magneto-optic-plasmonics (MOP) is a relatively new class that merges the three sub-fields: optics, magnetics, and plasmonics of science. The main ingredients of MOP material are ferromagnetic and ferromagnetic oxide materials like Fe, Co, Ni, magnetite, etc. where any change in permittivity tensor is conveyed by the presence of an applied external force or a magnetic field. The permittivity tensor is also dependent on the frequency of the incident optical radiation.

Magneto-optic materials can be used in various areas. These include determination of dynamic studies of film growth, detection of magnetic impurities, average free carrier effective mass, MO filters, atomic line filters, field sensors, memories, modulators and integrated optoelectronic devices like optical circulators, switches and isolators. The drives using thermomagnetic recording and magnetic recording also use MO materials. Some other fields where MO materials are used include spintronics and MO microscopy. The most recent application is the biomedical field where efforts are in process to develop a biosensor that is the most sensitive to date.

The discovery of magneto-optic effects in metals and dielectric is not new (it was very first discovered and demonstrated by Michael Faraday in 1845). However, the application of MO in spintronics and recording have been found only in the 1990s. The importance of magneto-optic in sensing and imaging has emerged only in the last decade.

The recent application of magnetic-field on bio-sensing is shown in the picture below. The picture demonstrates a right-angled isosceles prism, indexed matching liquid, lenses, buffer layer, optical laser source, a substrate with transducer/sample and a photodetection (PD) system.

The future of magneto-plasmonic based nanostructures is extremely bright. These nanostructures display exceptional properties like high sensitivity, strong enhancement of electromagnetic fields, the possibility of obtaining high photothermal conversion efficiencies, large signal to noise ratio and rich spectral responses at applied magnetic fields, makes them outstanding, unique and sought for material for various applications.

Applications of Magnetoplasmonics:

The application of magnetoplasmonics has a vast range of possibilities in a number of fields including clinical therapy, biophysics, diagnostics, bio-imaging, environmental monitoring, biophysics, chemical and biological sensing, ultra-fast molecular sensing for early disease detection, magneto-plasmon-enabled photo-thermal therapy, magneto-plasmon-assisted laser welding, plasmon-assisted photo-acoustic imaging and magneto-plasmon-enhanced spectroscopies, like SERS for magneto-plasmonic structures and fields are expected to extend the production of energy and in the exploration of space as well.

Some other additional areas where magnetoplasmonic-based devices and structures can be used are magneto-plasmon based isolators, photo-detectors, harvesting and conversion of solar energy along with the coupling of magneto-plasmons to chemical reactions in order to achieve high selectivity and activity for energy saving, switching and sensing and tuning of magneto-optical properties at the femtosecond speed.

Some other highly promising areas where the potential of this technology can be fully utilized include the development of bio-nanomagnetic and magetoplasmonic bioengineering, high-performance magnetronic devices and green energy, biomedicine and biology to mention a few.

Dr. Rizal has done extensive research on Magneto-optic-plasmonics and his paper can be accessed Here

Surface Plasmon Resonance

Surface Plasmon Resonance (SPR) is the reminiscent oscillation of electrons conductions stimulated by incident light at the interface between negative and positive material. Through SPR the binding of the molecules can be measured in real-time without the use of any labels.

Surface Plasmon Resonance is used to observe the change in refractive index at any surface. SPR occurs when the total internal reflection of polarized light takes place at a metal film. SPR instruments are generally used to measure affinity and the binding kinetics of the molecular interactions. SPR can be used to measure the binding between a protein and an antibody or in between two proteins or in between DNA and a protein and many more.

The technique of SPR is Unique:

The technique of SPR is unique because it is among one of the few techniques which allow the determination of binding kinetics, not just binding affinity which is commonly observed in traditional techniques like ELISA. The determination of binding kinetics is only through a biosensing technique that provides the real-time data of both the association and dissociation phases of the interaction. This data provides insights of both the binding stability and stability of the interaction in detail. Such insights are very critical for many industries and research areas as they help researchers to determine the molecules which are interacting also why are they interacting and how strongly do they interact.

Advantages of SPR:

There are several advantages to SPR. Some of them include:

  • SPR is Label-free that means it is less expensive and easier to perform as compared to other common assay techniques.
  • SPR is easily available in small sample volumes.
  • SPR is highly sensitive which means it can be used for small molecules to large proteins.
  • SPR provides for Real-Time readings hence giving a deeper insight into the binding kinetics as compared to other affinity techniques.
  • SPR is quantitative.

Applications of SPR:

The SPR data is critical in many industries and has been in use for over 25 years by companies like GSK, Roche and Pfizer and by many universities throughout the world. Some examples of applications include:

  • Developing and screening new biotherapeutics and new pharmaceuticals
  • Quality control in the monitoring of the bioprocess
  • Development of new diagnostic assays
  • In basic research like characterizing and discovering protein function, disease mechanisms etc.

To know more about it, Click Here.

Biosensor Principle

Introduction

A biosensor is a diagnostic device used for the detection of a physical or chemical substance that combines a biological component with a physio-chemical detector. The reader of the biosensor device connects with the signal processors or associated electronics, which are primarily responsible for the display of results in a user-friendly manner. Now it is possible to generate a user-friendly display that includes a transducer and sensitive elements.

There are primarily two types of biosensors, some are portable and others are either the fixed type or bench-type. Some examples are electrochemical, catalytic Bead, photoionization, infrared, infrared Image, ultrasonic, holographic detectors/sensors and more recently surface plasmon resonance (SPR) and magneto-optic (MO) surface plasmon resonance (MOSPR)-based sensors.

The major requirement of any biosensors depends on the approach in terms of commercial applications and research in the identification of the target molecule, as well as the availability of an appropriate biological recognition element.

The most common and best example of a commercial biosensor is the blood glucose biosensor. This sensor utilizes the glucose-oxidase enzyme that breaks down the glucose. In this process of breakdown, it first oxidizes glucose and uses two electrons to reduce the flavin adenine dinucleotide (FAD) — an enzyme component to FADH2 which is then oxidized by the electrode in several steps. The resulting current is a measure of the concentration of glucose. In this scenario, the electrode is the transducer, and the enzymes are the biologically active components.

Applications of Biosensors

Most optical biosensors are based on the principle of surface plasmon resonance (SPR). The SPR occurs when a thin layer of gold on a high refractive index glass surface absorbs the laser light and produces electron waves (known as surface plasmons) on the gold surface. This condition arises at a specific angle and wavelength of the incident light. The phenomena depend on the binding of a target analyte to a receptor that produces a measurable signal.

One way the SPR sensors operate is by using a sensor chip. The chip consists of a plastic cassette supporting a glass plate, coated with a microscopic layer of gold on one of the sides. where the optical detection apparatus of the instrument lies. The opposite side of the plate is then attached to the microfluid flow system that allows the passage of reagents in the solution.

The glass sensor chip of this side can be modified in a number of ways, which allows easy attachment of molecules of interest. Hence, the refractive index at the flow side of the chip surface has a direct influence on the behaviour of the light reflected off the sensor side. The flow side of the chip has an effect bonded on the refractive index of the material of interest and in this way, biological interactions are measured to a high degree of sensitivity. As a result, the refractive index of the medium changes near the surface when the biomolecules are attached to the surface and the angle of SPR varies as the function of this change.

Biological biosensors are designed from a genetically modified form of a native protein or enzyme. The protein is configured for the detection of a specific analyte and the ensuing signal is read with the help of detection instruments such as fluorometers or luminometers, to name a few. To read more about “Biosensors” Click Here.

Biosensor Technology-a Game Changer

Biosensors are new, highly innovative devices used for detecting biological responses, which are converted into measurable data.

How Biosensors Work:

Biosensors capture biological data, which is first analyzed using algorithms and then translated into measurable quantity.

Advantages of Biosensors:

  • Detects & Prevents Progression of Illness
    Research has shown that biosensors highly effective in diagnosing the early onset of diseases caused by various infections. This technology has the ability to be used daily, as the sensors can be incorporated to mobile devices, which can synchronize personalized data to applications, which aids in remotely monitoring health. This data can be immediately available to physicians, which allows treatment to be more convenient and efficient. Early detection of these diseases can allow treatment to begin promptly, which increases the likely-hood of recovery.
  • Detects Blood-Alcohol Levels in the Body
    A recently designed wearable device called “Biosensor Tattoo” can sense the changes in the electric currents flowing through the sweat of the user. These changes in the electric currents determine blood-alcohol levels in the body. This information is then sent to the user’s mobile phone to alert them. This will allow users to make informed decisions as to whether it is safe to drive.
  • Detects Blood-Glucose Levels in the Body
    The advancement in biosensor technology allows diabetics to monitor their glucose levels in a more affordable, convenient way. This non-invasive device eliminates the use of multiple test strips.
  • Biosensor Technology can have a Huge Impact 
    Biosensor technology currently has a huge impact on the healthcare industry, but with time and innovation these sensors can revolutionize the way diseases are diagnosed. Biosensors play an important role when it comes to monitoring health.

Future of Plasmonic Biosensors

Introduction

Biosensors represent the technological side of the living senses that have found a routine application in amperometry enzyme electrodes for the decentralization of blood glucose measurement, for the interaction analysis by surface plasmon resonance in drug development, and to some extent, DNA chips for enzyme polymorphisms and expression analysis. These technologies have already reached a highly advanced level and need only minor improvement now.

Fundamentals

In the field of optics, the phenomenon of surface plasmon resonance (SPR), is widely used as optical biosensors. This was established from studies that involved the excitation of the surface plasmons on the metallic surfaces, especially noble metals. In this process, the metallic surfaces are exposed to light, a photon is trapped near them and that prompts electrons to move as a single entity. The oscillation of electrons on the metal film results in the formation of an electromagnetic field that decays out on the surface and is also known as the evanescent field.

Potential Applications

Point of Care

  • One of the primary applications of the biosensors is the development of the point- of-care testing system for prompt and precise therapy. This can be achieved by the integration of technologies such as disposable chips, portable platforms, miniaturization of the analytical machines and so on.
  • A smartphone-integrated analytical system can be used, which enables rapid diagnoses by allowing the data collected on the smartphone to be connected to medical doctors and institutions via Wi-Fi. In addition to this, disposable chips have also been developed as convenient devices with a simple operation such as color-change detection. Thus, the SPR sensors (e.g. immunosensor, etc.) have a great potential to utilize measurement of bio-markers due to their label-free, cost-effective analysis, and with the rapid response time. Because of these advantages, SPR-based sensors can facilitate high throughput and multiplex measurement of biomarkers when integrated with the microfluidic system.

SPR and Sensitivity

One of the challenges of the existing surface plasmon resonance (SPR) based sensors is that the sensitivity (if you would like to learn more about the biosensor sensitivity, click here) is not high enough for the measurement of biomarkers in small volumes of body fluids. Also, it is not a natural color change-based method, except for that of Au nano-particles.

Several efforts have been made to improve the sensitivity of the biosensors. These include metal surfaces, magnetic activity, grating or photonic crystals, etc. Meanwhile, the plasmonic effect which stimulates the SPR phenomena, can also stimulate another phenomenon that can also be applied to the development of immuno-sensors, including surface-enhanced Raman scattering (SERS), fluorescence resonance energy transfer (FERT), and metal-enhanced fluorescence) (MEF). If the SERS, FRET, MEF based analytical methods could be assimilated with an SPR-based sensor that employs plasmonic effects, targets can be measured in a better way and the drawbacks of each analytical method can be supplemented.

MOSPR and Sensitivity

  • Several plasmonic-based analytical methods have advantages with nano-structures and noble metals, and there is a possibility to develop a magneto-optic SPR sensor with high performance using an integrated platform.
  • Significant potential exists to develop MOSPR-based sensors with noble metals and nanostructures, for improvement in functionality as effective biosensors. The best advantage of this analytical method is in-situ, label-free detection. This could result in the development of several new types of sensors that can measure targets in a simple, rapid and cost-effective manner.


Figure: A microfluidic channel incorporated biosensor, and optical excitation scheme.

Currently, there are signific shortcomings in SPR-based immuno-sensor systems which is a challenge for effective detection. However, now the integration of magneto-plasmonic-based sensing systems can offer a breakthrough for the development of effective MOSPR sensors, for early diagnosis and point of care testing of various diseases, which in turn can significantly improve pharmaceutical, biomedical and clinical applications.

For more information, Click Here.