With the development of COVID-19, widely available tests are in great demand. Naked-eye SARS-CoV-2 test kits have recently been developed as home tests, but their sensitivity and accuracy are sometimes limited. Smartphones can convert various signals into digital information, potentially improving the sensitivity and accuracy of these home tests. Herein, we summarize smartphone-based detections for SARS-CoV-2. Optical detections of non-nucleic acids using various sensors and portable imaging systems, as well as nucleic acid analyses based on LAMP, CRISP, CATCH, and biosensors are discussed. Furthermore, different electrochemical detections were compared. We show results obtained using relatively complex equipment, complicated programming procedures, or custom smartphone apps, and describe methods for obtaining information with only simple setups and free software on smartphones. Then, the combined costs of typical smartphone-based detections are evaluated. Finally, the prospect of improving smartphone-based strategies to achieve broad availability of SARS-CoV-2 detection is proposed. 

https://doi.org/10.1016/j.trac.2022.116878

Achieving broad availability of SARS-CoV-2 detections via smartphone-based analysis


 A simple, rapid, and environmentally friendly green approach for synthesizing Fe3O4 and Fe3O4/chitosan nanoparticles with various concentrations was developed. The nanoparticles had a spherical shape with a cubic inverse spinel structure. The functionalization of the Fe3O4 using chitosan increased the crystallite size of nanoparticles from 7.2 to 7.8 nm. The Fourier transform infrared spectra of the Fe3O4/chitosan showed the existence of the characteristic peaks of chitosan in addition of 578 cm−1, which corresponds to the Fe−O group. The UV-visible spectra demonstrated a wide absorption band with the appearance of small peaks of chitosan absorption at 205 and 215 nm. The saturation magnetization of Fe3O4 was 54.1 emu/g. The surface plasmon resonance (SPR) measurements showed an enhancement in the SPR angle as the chitosan concentration increased, wherein the angle shift values from 0.17° to 1.91°. The chitosan covering the Fe3O4 surface caused the refractive index to change, which increased the SPR angle shift. The obtained results indicated that the SPR properties of the Fe3O4 were significantly improved by modification with chitosan. These results also indicated that the use of chitosan in Fe3O4 can enhance SPR properties, which has potential for future SPR-based sensor applications.

https://iopscience.iop.org/article/10.1149/2162-8777/ac8b36/pdf

Green Synthesis of Fe3O4/Chitosan Nanoparticles Utilizing Moringa Oleifera Extracts and Their Surface Plasmon Resonance Properties

Interfacial deposition of Ag nanozyme on metal-polyphenol nanosphere for SERS detection of cellular glutathione.

Recent trends in non-reactive light driven Micro/-nano propellers and rotors

Gold nanostars (AuNSs) are synthesized using a seed-mediated growth method. The synthesized AuNSs solution is stable and shows a localized surface plasmon resonance (LSPR) band in the visible range, which is confirmed using ultraviolet–visible (UV–Vis) spectroscopy. Furthermore, the as-synthesized AuNSs were functionalized with melamine and used as a sensor for the colorimetric detection of uric acid (UA). The detection mechanism could be assessed through various analytical techniques such as UV–Vis spectroscopy, Fourier transform infrared (FT-IR) spectroscopy, dynamic light scattering (DLS), zeta potential, field emission scanning electron microscopy (FE-SEM), and transmission electron microscopic techniques. These methods exhibited a good linear regression between the absorption ratio of LSPR band of melamine–AuNSs and the concentration of UA (0–120 µM), with the detection limit of 8.50 nm. As a result, UA was quantitatively detected in biofluids by using melamine-AuNSs as a colorimetric sensor, revealing melamine–AuNSs–based colorimetric approach which could be used as a simple platform for UA assay in biofluids. Graphical Abstract This is a visual representation of the abstract.

Nataly Chubarova

Papers

Diverse bio-sensing and therapeutic applications of plasmon enhanced nanostructures