One of the major challenges on the way to low‐cost, simple, and effective cancer treatments is the lack of smart anticancer drug delivery materials with the requisite of site‐specific and microenvironment‐responsive properties. This work reports the development of plasma‐engineered smart drug nanocarriers (SDNCs) containing chitosan and nitrogen‐doped graphene quantum dots (NGQDs) for drug delivery in a pH‐responsive manner. Through a customized microplasma processing, a highly cross‐linked SDNC with only 4.5% of NGQD ratio can exhibit enhanced toughness up to threefold higher than the control chitosan group, avoiding the commonly used high temperatures and toxic chemical cross‐linking agents. The SDNCs demonstrate improved loading capability for doxorubicin (DOX) via π–π interactions and stable solid‐state photoluminescence to monitor the DOX loading and release through the Förster resonance energy transfer (FRET) mechanism. Moreover, the DOX loaded SDNC exhibits anticancer effects against cancer cells during cytotoxicity tests at minimum concentration. Cellular uptake studies confirm that the DOX loaded SDNC can be successfully internalized into the nucleus after 12 h incubation period. This work provides new insights into the development of smart, environmental‐friendly, and biocompatible nanographene hydrogels for the next‐generation biomedical applications.

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Environmental contamination and energy shortage are among the most critical global issues that require urgent solutions to ensure sustainable ecological balance. Rapid and ultrasensitive monitoring of water quality against pollutant contaminations using a low-cost, easy-to-operate, and environmentally friendly technology is a promising yet not commonly available solution. Here, we demonstrate the effective use of plasma-converted natural bioresources for environmental monitoring. The energy-efficient microplasmas operated at ambient conditions are used to convert diverse bioresources, including fructose, chitosan, citric acid, lignin, cellulose, and starch, into heteroatom-doped graphene quantum dots (GQDs) with controlled structures and functionalities for applications as fluorescence-based environmental nanoprobes. The simple structure of citric acid enables the production of monodispersed 3.6 nm averaged-size GQDs with excitation-independent emissions, while the saccharides including fructose, chitosan, lignin, cellulose, and starch allow the synthesis of GQDs with excitation-dependent emissions due to broader size distribution. Moreover, the presence of heteroatoms such as N and/or S in the chemical structures of chitosan and lignin coupled with the highly reactive species generated by the plasma facilitates the one-step synthesis of N, S-codoped GQDs, which offer selective detection of toxic environmental contaminants with a low limit of detection of 7.4 nM. Our work provides an insight into the rapid and green fabrication of GQDs with tunable emissions from natural resources in a scalable and sustainable manner, which is expected to generate impact in the environmental safety, energy conversion and storage, nanocatalysis, and nanomedicine fields.

4-nitrophenol (4-NP) is one of the organic pollutants that can come up from pesticides, explosives, dyes, and pharmaceutical industries. Since it can be extremely harmful to humans and other living organisms, it is crucial to have a system that can effectively detect the presence of 4-NP. Here, we report the microplasma synthesis of nitrogen-doped graphene quantum dots (N-GQDs) for fluorescence-based detection of 4-NP. Through Förster resonance energy transfer (FRET) between donor N-GQDs to the acceptor 4-NP, synthesized N-GQDs can be employed for the detection of 4-NP starting from 0.5 to 100 µM with a limit of detection as low as 95.14 nM. 4-NP detection also demonstrates remarkable stability over all pH values and wide temperatures (10–60 °C), indicating the high possibility for robust organic pollution monitoring. Our work provides insight into a simple, fast, and environmentally friendly method for synthesizing N-GQDs at ambient conditions usable for environmental nanosensors.

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