Graphene quantum dot (GQD) is one of the youngest superstars of the carbon family. Since its emergence in 2008, GQD has attracted a great deal of attention due to its unique optoelectrical properties. Non‐zero bandgap, the ability to accommodate functional groups and dopants, excellent dispersibility, highly tunable properties, and biocompatibility are among the most important characteristics of GQDs. To date, GQDs have displayed significant momentum in numerous fields such as energy devices, catalysis, sensing, photodynamic and photothermal therapy, drug delivery, and bioimaging. As this field is rapidly evolving, there is a strong need to identify the emerging challenges of GQDs in recent advances, mainly because some novel applications and numerous innovations on the ease of synthesis of GQDs are not systematically reviewed in earlier studies. This feature article provides a comparative and balanced discussion of recent advances in synthesis, properties, and applications of GQDs. Besides, current challenges and future prospects of these emerging carbon‐based nanomaterials are also highlighted. The outlook provided in this review points out that the future of GQD research is boundless, particularly if upcoming studies focus on the ease of purification and eco‐friendly synthesis along with improving the photoluminescence quantum yield and production yield of GQDs.

Wastewater analysis of pathogens, particularly SARS-CoV-2, is instrumental in tracking and monitoring infectious diseases in a population. This method can be used to generate early warnings regarding the onset of an infectious disease and predict the associated infection trends. Currently, wastewater analysis of SARS-CoV-2 is almost exclusively performed using polymerase chain reaction for the amplification-based detection of viral RNA at centralized laboratories. Despite the development of several biosensing technologies offering point-of-care solutions for analyzing SARS-CoV-2 in clinical samples, these remain elusive for wastewater analysis due to the low levels of the virus and the interference caused by the wastewater matrix. Herein, we integrate an aptamer-based electrochemical chip with a filtration, purification, and extraction (FPE) system for developing an alternate in-field solution for wastewater analysis. The sensing chip employs a dimeric aptamer, which is universally applicable to the wild-type, alpha, delta, and omicron variants of SARS-CoV-2. We demonstrate that the aptamer is stable in the wastewater matrix (diluted to 50%) and its binding affinity is not significantly impacted. The sensing chip demonstrates a limit of detection of 1000 copies/L (1 copy/mL), enabled by the amplification provided by the FPE system. This allows the integrated system to detect trace amounts of the virus in native wastewater and categorize the amount of contamination into trace (<10 copies/mL), medium (10–1000 copies/mL), or high (>1000 copies/mL) levels, providing a viable wastewater analysis solution for in-field use.

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Effects of graphene oxide nanomaterials addition and oxidation level on ignition delay and burning rate of ethanol droplets are experimentally investigated. Three graphene oxide samples are synthesized and characterized. Separate high-speed OH * chemiluminescence and high-speed shadowgraphy images are collected. The results suggest that increasing the loading concentration from 0 to 0.1% (by weight) generally increases the ignition delay, except for ethanol doped with the highly oxidized graphene. The results show that unlike pure ethanol droplets, atomization may occur for the doped ethanol droplets.It is demonstrated that, independent of the tested conditions, atomization occurs in the second half of the droplet lifetime. The probability density function of the atomized baby droplet diameter, initial projected velocity, and length of the projected trajectory are similar for all tested conditions and independent of the oxidation level and loading concentration of the additives. The joint probability density function calculated for the atomization-related parameters against one another suggests that the majority of the baby droplets feature a relatively short lifetime, indicating they may potentially burn inside the flame envelope. Using droplet surface regression curves versus time, the burning rate for periods in which the atomization does not occur, and for the periods that the atomization is present are estimated. The former burning rate is shown to enhance by increasing the loading concentration and reducing the oxidation level of graphene. However, supported by Fourier-Transform Infrared spectroscopy of the graphene oxide samples, it is found that a maximum increase in the latter burning rate for both loading concentrations occurs for ethanol doped with the graphene oxide that features maximum amount of infrared radiation absorption. To quantify the effect of atomization on the droplet mass loss, a conservation of mass framework is utilized, and it is shown that relatively intense atomization suppresses the mass loss. Doping ethanol with graphene oxide and increasing the loading concentration from 0.01 to 0.1% enhances the overall burning rate, with a maximum enhancement of 8.4% pertaining to addition of reduced oxidized graphene oxide and for the loading concentration of 0.1%.