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Coating nanosized anticancer drug delivery systems (DDSs) with poly(ethylene glycol) (PEG), the so-called PEGylation, has been proven an effective method to enhance hydrophilicity, aqueous dispersivity, and stability of DDSs. What is more, as PEG has the lowest level of protein absorption of any known polymer, PEGylation can reduce the clearance of DDSs by the mononuclear phagocyte system (MPS) and prolong their blood circulation time in vivo. However, the “stealthy” characteristic of PEG also diminishes the uptake of DDSs by cancer cells, which may reduce drug utilization. Therefore, dynamic protection strategies have been widely researched in the past years. Coating DDSs with PEG through dynamic covalent or noncovalent bonds that are stable in blood and normal tissues, but can be broken in the tumor microenvironment (TME), can achieve a DePEGylation-based “tumor-triggered” targeting or intracellular drug release, which can effectively improve the utilization of drugs and reduce their side effects. In this review, the stimuli and methods of “tumor-triggered” targeting or intracellular drug release, based on DePEGylation, are summarized. Additionally, the targeting and intracellular controlled release behaviors of the DDSs are briefly introduced.

In general, the total antioxidant capacity (TAC) in food is vital for evaluating the quality of antioxidant food and health monitoring. Most studies about the access of the TAC in food are mainly focused on typical colorimetric strategies. Herein, a simple and sensitive strategy for TAC in beverages and fruit has been proposed based on amino/hydroxyl-functionalized carbon dots (N 2 H 4 -CDs) and Fe 3+ . The fluorescence (FL) of N 2 H 4 -CDs at 650 nm can be effectively and selectively quenched via the formation of the nonfluorescence complex (Fe 3+ /N 2 H 4 -CDs). Moreover, the FL of N 2 H 4 -CDs is concentrated in the red region, which can eliminate the interference in complex biological environments. Interestingly, based on the theoretical calculations of density functional theory (DFT), we have confirmed that the surface amino and hydroxyl play an essential role in selective association with Fe 3+ , resulting in effective quenching. Moreover, because Fe 3+ can be reduced by antioxidants to Fe 2+ , the quenched FL of N 2 H 4 -CDs can be restored in the presence of ascorbic acid (AA) and glutathione (GSH). Therefore, the typical antioxidants (AA) and especially certain thiol antioxidants (GSH) can also be analyzed by the proposed strategy. More importantly, we have proved that this strategy is successfully utilized for analyzing the TAC in beverages and fruit.

Pickering emulsions stabilized by food-grade colloidal particles have attracted increasing attention in recent years due to their “surfactant-free” nature. In this study, the alkali-treated zein (AZ) was prepared via restricted alkali deamidation and then combined with sodium alginate (SA) in different ratios to obtain AZ/SA composite particles (ZS), which were used to stabilize Pickering emulsion. The degree of deamidation (DD) and degree of hydrolysis (DH) of AZ were 12.74% and 6.58% respectively, indicating the deamidation occurred mainly in glutamine on the side chain of the protein. After the treatment with alkali, AZ particle size decreased significantly. Moreover, the particle size of ZS with different ratios was all less than 80 nm. when the AZ/SA ratio was 2:1(Z2S1) and 3:1(Z3S1), the three-phase contact angle (θo/w) were close to 90°, which was favorable for stabilizing the Pickering emulsion. Furthermore, at a high oil phase fraction (75%), Z3S1-stabilized Pickering emulsions showed the best long-term storage stability within 60 days. Confocal laser scanning microscope (CLSM) observations showed that the water-oil interface was wrapped by a dense layer of Z3S1 particles with non-agglomeration between independent oil droplets. At constant particle concentration, the apparent viscosity of the Pickering emulsions stabilized by Z3S1 gradually decreased with increasing oil phase fraction, and the oil-droplet size and the Turbiscan stability index (TSI) also gradually decreased, exhibiting solid-like behavior. This study provides new ideas for the fabrication of food-grade Pickering emulsions and will extend the future applications of zein-based Pickering emulsions as bioactive ingredient delivery systems.

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