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The COVID-19 pandemic has strained healthcare systems. Sensitive, specific, and timely COVID-19 diagnosis is crucial for effective medical intervention and transmission control. RT-PCR is the most sensitive/specific, but requires costly equipment and trained personnel in centralized laboratories, which are inaccessible to resource-limited areas. Antigen rapid tests enable point-of-care (POC) detection but are significantly less sensitive/specific. CRISPR-Cas systems are compatible with isothermal amplification and dipstick readout, enabling sensitive/specific on-site testing. However, improvements in sensitivity and workflow complexity are needed to spur clinical adoption. We outline the mechanisms/strategies of major CRISPR-Cas systems, evaluate their on-site diagnostic capabilities, and discuss future research directions. CRISPR-based detection systems are poised to emerge as the next-generation point-of-care (POC) diagnostic platform, and have the potential to marry the advantages of RT-PCR (sensitive/specific) and rapid test kits (RTKs) (fast turnaround, user-friendly). These systems also circumvent the deficiencies of both RT-PCR (long turnaround, equipment/trained user requirement) and RTKs (low sensitivity). These POC platforms play a crucial role for effective medical intervention and transmission control of infectious diseases such as COVID-19. For these systems to be widely adopted clinically, developments have been made to enhance the thermal compatibility of CRISPR with isothermal amplification assays, towards a one-step, one-pot platform. [ABSTRACT FROM AUTHOR]

3-dimensional (3D) nanostructures have gained broad attention in the field of microelectronics and nanotechnology owing to their fascinating properties and potential for novel applications. To enable successful fabrication of the nanostructure, deep understanding on their growth mechanism is an absolute prerequisite. In this study, thin film of hematite (α-Fe 2 O 3) nanoflakes is successfully converted to nanoflowers using aerosol-assisted chemical vapour deposition (AACVD) technique simply by supplying high amount of oxygen and regulating the deposition time. The crystal structure and morphological properties including thickness and roughness of the film are thoroughly investigated to provide a clear explanation on the growth mechanism of α-Fe 2 O 3 by AACVD. Results indicate that (110) crystal plane is the predominant factor that influence the formation of nanoflowers with unique pyramidal nanostructure. This structure causes the film thickness to increase linearly while the surface roughness shows a logarithmic growth trend. The samples are further employed in photoelectrochemical (PEC) water splitting as photoanode where 40 min deposition period is the optimum condition for achieving PEC photocurrent density of up to 585 μA/cm2 at 1.2 V vs. Ag/AgCl. The major contributor towards the performance enhancement is the large surface area and high light absorption of α-Fe 2 O 3 nanoflowers as this parameter provides greater sites for photocatalytic activity, greater charge generation and enhanced charge carrier separation efficiency. [ABSTRACT FROM AUTHOR]

Understanding the effect of electrochemical reaction on a particular material at the nanoscale level is essential for the application of solar conversion technology. Herein, electrochemical cyclic voltammetry (CV) treatment was applied on the α-Fe 2 O 3 thin films by varying the number of cycles between 0 and 100. The thorough investigation provides insight into the modifications on the properties of the CV-treated films. The performance of pristine and CV-treated α-Fe 2 O 3 as photoanodes are evaluated in the photoelectrochemical (PEC) water splitting cell. Consecutive CV scans up to the optimum number of cycles (50 cycles) promote the photocurrent density, where the photocurrent value at 0.6 V Ag/AgCl becomes about 1.5 times higher than the pristine α-Fe 2 O 3. This remarkable enhancement in PEC performance is due to the synergistic effect between the change of crystal orientation, the enhancement of surface oxygen vacancies and the increase of free charge carrier density. Our findings provide valuable information of possible pathway for improving the photoelectrochemical performance of a photoanode. Image 1 • Cyclic voltammetry treatment enhances PEC performance of α-Fe 2 O 3 by 1.5 times. • Change of crystal orientation improve electron mobility and hole trapping behaviour. • Surface oxygen vacancies generated by CV treatment facilitate water adsorption. • CV scanning induces greater free carrier density in the film. [ABSTRACT FROM AUTHOR]