Carbon quantum dots (CQD)-based nanosponges have been widely designed for tumor theranostic application recently. However, the drug content is usually lower with the shorter dynamic covalent linkers while the longer hydrophilic dynamic covalent linkers led to a significant premature drug leakage. Here, a hydrophobic linear reducible-responsive linker with two terminal aldehyde group was designed to crosslink the hydrazine-functionalized PEGylated CQDs (Hy-CQD-PEG), resulting in Hy-CQDss-PEG nanosponges. After doxorubicin (DOX) conjugation, the DOX-Hy-CQDss-PEG prodrug nanosponges were obtained with DOX content of 18.76 % and hydrodynamic diameter of 140 nm, respectively. The DOX-Hy-CQDss-PEG nanosponges were stable in the normal physiological medium with very low drug leakage and fluorescence, while they could disintegrate in the tumor intracellular microenvironment, releasing DOX and the hydrazine-functionalized CQDs for theranostic application.

Among explored nanomaterials, nanosponge-based systems have exhibited inhibitory effects for the biological neutralization of, and antiviral delivery against, severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). More studies could pave the path for clarification of their biological neutralization mechanisms as well as the assessment of their long-term biocompatibility and biosafety issues before clinical translational studies. In this review, we discuss recent advances pertaining to antiviral delivery and inhibitory effects of nanosponges against SARS-CoV-2, focusing on important challenges and opportunities. Finally, as promising approaches for recapitulating the complex structure of different organs/tissues of the body, we discuss the use of 3D in vitro models to investigate the mechanism of SARS-CoV-2 infection and to find therapeutic targets to better manage and eradicate coronavirus 2019 (COVID-19).

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Jenny
Journal Co-ordinator
Journal of Nano Research & Applications