This review introduces quantum dots (QDs) and explores their properties, synthesis, applications, delivery systems in biology, and their toxicity. QDs are one of the first nanotechnologies to be integrated with the biological sciences and are widely anticipated to eventually find application in a number of commercial consumer and clinical products. They exhibit unique luminescence characteristics and electronic properties such as wide and continuous absorption spectra, narrow emission spectra, and high light stability. The application of QDs, as a new technology for biosystems, has been typically studied on mammalian cells. Due to the small structures of QDs, some physical properties such as optical and electron transport characteristics are quite different from those of the bulk materials.

In the course of the coronavirus disease 2019 (COVID‐19), raising and reducing the function of Th17 and Treg cells, respectively, elicit hyperinflammation and disease progression. The current study aimed to evaluate the responses of Th17 and Treg cells in COVID‐19 patients compared with the control group. Forty COVID‐19 intensive care unit (ICU) patients were compared with 40 healthy controls. The frequency of cells, gene expression of related factors, as well as the secretion levels of cytokines, were measured by flow cytometry, real‐time polymerase chain reaction, and enzyme‐linked immunosorbent assay techniques, respectively. The findings revealed a significant increase in the number of Th17 cells, the expression levels of related factors (RAR‐related orphan receptor gamma [RORγt], IL‐17, and IL‐23), and the secretion levels of IL‐17 and IL‐23 cytokines in COVID‐19 patients compared with controls. In contrast, patients had a remarkable reduction in the frequency of Treg cells, the expression levels of correlated factors (Forkhead box protein P3 [FoxP3], transforming growth factor‐β [TGF‐β], and IL‐10), and cytokine secretion levels (TGF‐β and IL‐10). The ratio of Th17/Treg cells, RORγt/FoxP3, and IL‐17/IL‐10 had a considerable enhancement in patients compared with the controls and also in dead patients compared with the improved cases. The findings showed that enhanced responses of Th17 cells and decreased responses of Treg cells in 2019‐n‐CoV patients compared with controls had a strong relationship with hyperinflammation, lung damage, and disease pathogenesis. Also, the high ratio of Th17/Treg cells and their associated factors in COVID‐19‐dead patients compared with improved cases indicates the critical role of inflammation in the mortality of patients.

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Background: Coronavirus disease-2019 (COVID-19)-related organ failure is partly related to a sepsis-like syndrome and extreme pro-inflammatory cytokine release, named cytokine storm. Therapeutic strategies that prevent the production of or remove the pro-inflammatory cytokines could potentially be an effective therapy in critically afflicted COVID-19 patients. Methods:In this clinical trial study, from April until June 2020, 68 COVID-19 patients (35 vs. 33 controls) with severe critical symptoms, and PaO 2 /FiO 2 (P/F) ratio less than 200 mmHg either received a single standard therapy or a combination of standard treatment for COVID-19 combined with hemoperfusion (hemofilter, HA330 D Javfron) for 4 h, in 3 consecutive days. The length of hospital stay and mechanical ventilation, the resolution of radiologic abnormalities, and the mortality rate were defined as the primary outcomes.Results: Demographic characteristics, the acute physiology, and chronic health evaluation score of both groups were similar (p > 0.05). Importantly, we noticed a significant mortality rate reduction in the perfused group compared with controls (37.1% vs. 63.6%, p = 0.02), this positive effect was stronger among those with a P/F ratio higher than 75 (mortality rate of 84.7% for P/F ratio < 75 vs. 15.4% for P/F ratio ≥ 75, p = 0.02). Conclusions:The results imply that early start of hemoperfusion could be more effective and significantly reduce the mortality rate among COVID-19 patients with critical diseases.