Introduction: Nanotechnology is the science that deals with matter on the nanoscale, with sizes ranging from 1 to 100 nm. It involves designing, synthesising, characterising and applying these nanoscale materials. Nanoparticles (NPs) are known for their high surface-area to volume-ratio, surface charge density, low melting point, and distinguishably good optical/electrical properties. NPs exhibit an excellent drug delivery system, an effective contrast agent for vascular imaging, and effective antimicrobial activity. The biological synthesis of NPs is a simple, cost-effective, and environmentally friendly technique. This bottom-up technique utilises organisms’ enzymes/bio-compounds and a plant extract as capping and reducing agents. Cinnamomum species are known for their intrinsic antimicrobial, antidiabetic, antioxidant, anti-inflammatory, anticancer, and neuroprotective properties. This review summarises articles that greenly synthesised NPs using Cinnamomum species’ extracts, describing their methodologies, characterisation of the nanoparticles and their medical applications. Methods: A literature search has been conducted on databases PubMed, ScienceDirect, and Frontier on the green synthesis of metal nanoparticles (MNPs) using Cinnamomum-based extracts. Various articles reported the methodology of utilising Cinnamomum species’ extracts as reducing and capping agents. Only original lab articles were considered. Results: Various types of MNPs have been successfully synthesised. The most common Cinnamomum species utilised as extracts is Cinnamomum tamala. The most common applications tested were the MNPs’ antibacterial, antiviral, antifungal, antidiabetic and anticancerous activity. MNPs also had a role in treating mice-induced polycystic ovarian syndrome and Parkinson-like neurodegenerative diseases. Conclusion: Cinnamomum species have been successfully utilised in the green synthesis of various MNPs. Silver and Gold NPs were the most reported. These MNPs proved their efficacy in multiple fields of medicine and biology, especially their antibacterial, antiviral and antifungal activity. Notably, the newly synthesised NPs showed promising results in treating polycystic ovarian syndrome in rats.

The linear and nonlinear optical properties of a CdO film post-annealed in a hydrogen atmosphere for 30 min (CdO:H) were studied. The prepared CdO and CdO:H films were characterized by X-ray diffraction and UV-VIS-NIR absorption spectroscopy. Experimental data indicated that annealing in an H₂ atmosphere slightly compresses the CdO unit cell and widens the energy gap of CdO by about 3% relative to a nonhydrogenated film. This effect can be explained by the Burstein-Moss energy effect. The nonlinear absorption and nonlinear refractive index coefficients were determined and found to be higher than the values previously determined for nonhydrogenated CdO.

The wildfire-like spread of COVID-19, caused by severe acute respiratory syndrome-associated coronavirus-2, has resulted in a pandemic that has put unprecedented stress on the world’s healthcare systems and caused varying severities of socio-economic damage. As there are no specific treatments to combat the virus, current approaches to overcome the crisis have mainly revolved around vaccination efforts, preventing human-to-human transmission through enforcement of lockdowns and repurposing of drugs. To efficiently facilitate the measures implemented by governments, rapid and accurate diagnosis of the disease is vital. Reverse-transcription polymerase chain reaction and computed tomography have been the standard procedures to diagnose and evaluate COVID-19. However, disadvantages, including the necessity of specialized equipment and trained personnel, the high financial cost of operation and the emergence of false negatives, have hindered their application in high-demand and resource-limited sites. Nanoparticle-based methods of diagnosis have been previously reported to provide precise results within short periods of time. Such methods have been studied in previous outbreaks of coronaviruses, including severe acute respiratory syndrome-associated coronavirus and middle east respiratory syndrome coronavirus. Given the need for rapid diagnostic techniques, this review discusses nanoparticle use in detecting the aforementioned coronaviruses and the recent severe acute respiratory syndrome-associated coronavirus-2 to highlight approaches that could potentially be used during the COVID-19 pandemic.

This study presents a green method for synthesizing gold nanoparticles (AuNPs) and silver nanoparticles (AgNPs) employing gum arabic extract as a reducing and stabilizing agent. The synthesized nanoparticles are characterized using UV-Vis absorption spectroscopy and transmission electron microscopy (TEM). The visible color change and the presence of surface plasmon resonance (SPR) peaks confirmed the formation of silver and gold nanoparticles. The size of the nanoparticles was determined from the UV-Vis spectra data, and the results were compared to sizes measured by TEM. The nonlinear refraction (n2) and nonlinear absorption (β) coefficient of AgNPs and AuNPs at 488 and 514 nm were investigated under continuous wave mode excitation using the Z-scan technique. By fitting the experimental data to the Z-scan theoretical equations, the nonlinear refraction index and the nonlinear absorption coefficient were found. The origin of the nonlinearities was discussed, and it was proposed to be of thermal effect for the nonlinear refractive index and reverse saturation absorption for nonlinear absorption. Optical limiting and switching were demonstrated by taking advantage of the samples’ nonlinear optical characteristics. Received: 22 July 2024 | Revised: 25 September 2024 | Accepted: 26 November 2024 Conflicts of Interest The authors declare that they have no conflicts of interest to this work. Data Availability Statement Data are available from the corresponding author upon reasonable request. Author Contribution Statement Fryad Z. Henari: Conceptualization, Methodology, Software, Validation, Formal analysis, Investigation, Resources, Data curation, Writing – original draft, Writing – review & editing, Visualization, Supervision, Project administration. G. Roshan Deen: Conceptualization, Software, Formal analysis, Resources, Data curation, Visualization.