Viral infections such as HIV and SARS-CoV-2 have significantly increased morbidity in humans and resulted in a significant number of fatalities globally, hence early detection is crucial, particularly at a point-of-care (POC) setting to prevent the spread of these diseases. Localized surface plasmon resonance (LSPR) and green light-based Transmission spectroscopy techniques were used in this study to assess real-time molecular interactions between virus-spiked and nonspiked samples. The current study focuses on integrating selenium nanoparticles (SeNPs) with different optical photonic techniques for enhanced detection of HIV. Selenium nanoparticles were synthesized and functionalized with antibodies specific to HIV. Before and after bioconjugation with viral secondary antibodies, the SeNPs were characterized using Ultraviolet–visible (UV-Vis) spectroscopy, Dynamic light scattering (DLS), High-resolution transmission electron microscopy (HRTEM), and Raman spectroscopy, to elucidate their properties and confirm the presence of functional groups. After that, the NPs were integrated with plasmonic systems and used for the enhanced detection of HIV in comparison to traditional LSPR and Transmission spectroscopy. Colloidal selenium nanoparticles were successfully synthesized, using ND: YAG laser. The orange-colored, spherically shaped nanoparticles were evenly distributed and easily resuspended. Anti-HIV antibodies conjugated to SeNPs were added after HIV-specific antibodies were successfully immobilized on a glass slide substrate to react with HIV pseudovirus. The pseudovirus was effectively identified by the use of Transmission Spectroscopy and LSPR techniques. The two optical techniques for HIV detection were more sensitive after integrating selenium nanoparticles, as compared to the conventional Transmission spectroscopy and LSPR methods. This improved and highly sensitive approach may be utilized to identify viral infections early, thus combating the spread of infectious diseases.
Surface plasmon resonance is a label free optical detection technique, which responds to refractive index variations that are induced by molecular binding incidents or binding affinities. This occurrence takes place when electrons on a thin metal film are excited by the light directed at an incident angle and travel parallel to the film. The angle of incidence that triggers surface plasmon resonance is linked to the refractive index of the material and even an insignificant change in the refractive index will be detected due to the sensitivity of the method. Because of its sensitivity, this technique is used as a real-time analytical approach that can be used for many different applications such as investigating the antibody-antigen affinity. In this study, surface plasmon resonance and localized surface plasmon resonance were investigated for their efficiency in detecting human immunodeficiency virus concentrations. This was achieved by functionalizing gold coated slides using an antibody against the surface protein of the human immunodeficiency virus. To the functionalized gold coated surface, different viral concentrations were added. The samples were then analyzed on home-built surface plasmon resonance and localized surface plasmon resonance biosensing systems. The results showed that the systems detected differences in viral concentrations as demonstrated by resonance curve shifts and varying transmission intensities. These findings will used towards the development of an optical biosensor to be used at point of care system for the detection of viral load in resource limited settings.
Iodine is a crucial trace element that occurs in minute amounts in nature and is necessary for the development of bones, thyroid function, and several metabolic processes. Iodine deficiency, also known as hypothyroidism, affects millions of individuals worldwide, and an overabundance of iodine in the body is known as hyperthyroidism. The early identification of iodine with high sensitivity and selectivity is crucial for physiological impact since the abnormalities caused by iodine disorder can increase the frequency of mortality and mental impairments. This work aims to detect iodine using UV-Vis and Transmission spectroscopy and utilizing selenium nanoparticles as a probe. Selenium nanoparticles (SeNPs) were synthesized by ND: YAG laser method and characterized by Dynamic light scattering (DLS), and High-resolution transmission electron microscopy (HRTEM), while the conjugation of iodine to SeNPs was confirmed by Ultravioletvisible (UV-vis) spectroscopy. For iodine detection, UV-Vis and Transmission spectroscopy were used and compared and the synthesized colloidal and spherical selenium nanoparticles were utilized as a probe to detect iodine. The absorption peaks and a red shift for SeNPs changed upon the reaction with iodine and this shift may allow for the estimation of iodine concentration. The two methods will enable the detection and monitoring of iodine at different concentrations in the body thus preventing the onset of iodine-related diseases.
The COVID-19 pandemic is a once-in-a-lifetime public health threat. The pandemic has had a significant impact on both individuals and communities’ health, safety, and well-being. Because COVID-19 is an extremely infectious and has nonspecific symptoms that are easily confused with the typical flu, it is critical to have precise diagnostic techniques readily available. There is an urgent need for quick detection of the SARS-CoV-2 virus due to the COVID-19 pandemic. Here, we present highly sensitive gold nanoparticle-enhanced localized surface plasmon resonance (LSPR) technique for detection of SARS-CoV-2 virus. Surface plasmon resonance is a powerful method for getting label-free, real-time information about the interaction of two binding partners. Gold nanoparticles (AuNPs) were used as signal enhancers in the diagnosis of SARS-CoV- 2 virus using the LSPR technique. Gold nanoparticles are stable against oxidation, great biocompatible, non-cytotoxic and have unique optical characteristics. These specific properties make AuNPs the most potential nanomaterial for different applications such as ultrasensitive detection and biological sensing.
Chitosan-based nanoparticles (NPs) are well-known for their safely, nontoxicity, biocompatibility, and biodegradability. Since highly infectious viral diseases such as Covid-19 spread quickly, it is important to be able to diagnose these diseases early to prevent the infection from spreading. In this study, we developed a novel highly sensitive chitosan/gold nanoparticles based LSPR sensor for SARS-CoV-2 virus detection. Localized surface plasmon resonance (LSPR) is an optical phenomenon caused by collective electron charge oscillations in metallic nanoparticles excited by light source. The nanocomposites of gold nanoparticles (AuNPs) with chitosan were synthesized by the reduction technique. Chitosan/Au nanocomposites were synthesized by reducing gold salt using chitosan. Chitosan acted as a reducing/stabilizing agent to produce composites. SARS-CoV- 2 antibodies were conjugated with Chitosan/Au nanocomposites for detection of the target antigen using LSPR.
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