Shu Han,Ruiyang Sun,Hong Su,Jing Lv,Huan Xu,Di Zhang,Yuanshan Fu
This study aimed to investigate the ability of the novel materials D -α-tocopheryl poly(2-ethyl-2-oxazoline) succinate (TPOS) to construct pH-sensitive liposomes. TPOS was initially synthesized and characterized by TLC, FTIR, and 1 H-NMR. The buffering capacity of polyethylene glycol- distearoyl phosphatidylethanolamine (PEG-DSPE) and TPOS was determined by acid-base titration, and TPOS displayed a slower downtrend and gentler slope of titration curve than PEG-DSPE within pH 7.4–5.0. Studies on the in vitro drug release demonstrated that TPOS modified docetaxel (DOC) liposomes (TPOS-DOC-L) had a slower drug-release rate at pH 7.4 similar to PEGylated-DOC liposomes (PEG-DOC-L), whereas the release rate reached approximately 86.92% ± 1.69% at pH 6.4. In vitro cellular uptake assays by microplate reader, and flow cytometry revealed that TPOS modified coumarin 6 liposomes (TPOS-C6-L) had stronger cellular uptake at pH 6.4 than that at pH 7.4 ( P < 0.01). Conversely, for PEGylated C6 liposomes (PEG-C6-L) and conventional C6 liposomes (C6-L), very similar cellular uptakes were exhibited at different pH values. Confocal laser scanning microscopy images showed that PEG-C6-L and C6-L were mainly located in lysosomes. By contrast, TPOS-C6-L showed broader cytoplasmic release and distribution at 4 h. MTT assay showed that the cytotoxicity of TPOS-DOC-L was similar to that of PEG-DOC-L and conventional DOC liposomes (DOC-L) at the same DOC concentration and at pH 7.4, but was much lower than those at pH 6.4 after 48 h of incubation. The apoptosis of PEG-DOC-L and DOC-L had no remarkable improvement with decreased pH from 7.4 to 6.4. Meanwhile, TPOS-DOC-L significantly induced the apoptosis of HeLa cells with decreased pH. Therefore, TPOS can be a biomaterial for the construction of a pH-sensitive drug delivery system.
The control and detection of sunset yellow (SY) are very important due to the high risk of harmful effects on humans caused by excessive intake. In this work, we reported the synthesis of hollow mesoporous carbon spheres (HMCS) and their application in developing a novel electrochemical sensor for SY. Initially, three hollow carbon spheres with different sizes and pore structures were synthesized by adjusting the ratio of TPOS and TEOS using the hard-templating approach. In comparison, HMCS showed the smallest diameter (290 nm), the largest surface area (2229.1 m 2 g −1 ), and a high content of mesoporous structure. This provides a structural basis for high-efficiency pre-concentration of SY on the surface of the HMCS-modified electrode, which effectively improves its electrocatalytic activity . Under optimized conditions, the HMCS/GCE sensor showed a wide linear range varying from 0.0015 − 4 µM, with an ultralow LOD (0.12 nM). Moreover, the HMCS/GCE sensor was deployed for the detection of SY with the advantages of impressive anti-interference ability, satisfactory reproducibility, good repeatability as well as long-term stability. The proposed sensor has been successfully used for the detection of SY in food samples with spiked recoveries of 91.1–103.3%, showing the promising application of the method for the detection of SY in the food matrix.
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