Deep eutectic solvents (DESs) have received widespread attention for their advantages of good electrical conductivity, stability, environmental friendliness, and easy preparation with a wide range of applications. However, it was not until recent years that DESs were used as gel electrolytes as environmentally friendly alternatives to ionic liquids (ILs). In this review, we first introduce the DESs related eutectogels (or ion gels), then introduce the types and applications of the gels, the opportunities and challenges of them are also summarized.

Hierarchical targeting strategy can combat the sequential drug delivery barriers by changing their properties with response to tumor stimuli. Among these strategies, much less attention has been paid to address the issues of rapid tumor clearance and insufficient cellular translocation. In this work, we demonstrate that a transactivator of transcription (TAT)-presenting nanomedicine (^DATAT-NP/Pt), apart from improving tumor accumulation and cellular uptake, can simultaneously enhance tumor retention and promote nuclear translocation of encapsulated platinum prodrugs, and thus improve therapeutic efficacy. Specifically, a protecting 2, 3-dimethylmaleic anhydride (DA) corona on the nanomedicine prevented the TAT peptide from serum. ^DATAT-NP/Pt efficiently accumulated at the tumor site through the enhanced permeability and retention (EPR) effect, followed by acid-triggered TAT presenting within the tumor acidic microenvironment (pH ~ 6.8). The exposed TAT peptide augmented tumor retention and nuclear translocation of ^DATAT-NP/Pt. We used a tumor-on-a-chip microfluidic system to real-time mimic and analyze tumor accumulation and retention at physiological flow conditions and revealed that surface absorption of nanomedicines on tumors was critical in determining their tumor retention and clearance. Furthermore, the TAT peptide rapidly translocated the ^DATAT-NP/Pt into the perinuclear region, allowing for higher nuclear platinum concentrations and increased Pt-DNA adduct formation in nuclei, which consequently reversed cisplatin resistance. Our work presents a new strategy to overcome pathophysiological barriers of tumor clearance and insufficient cellular translocation and provides new insights for the design of cancer nanomedicines.