Sugar/sugar alcohol with glycerol as co-plasticizers for high-content starch/PBAT blown films: from fine structure to physicochemical properties.

BACKGROUND: Glycerol is a well-known plasticizer for starch-based materials, but it easily migrates during starch retrogradation, thereby deteriorating the films' properties. We hypothesized that the performance of high-content starch/poly(butylene adipate-co-terephthalate) (PBAT) films could be enhanced by using sugar/sugar alcohol (glucose, sucrose and sorbitol) as natural, green and edible co-plasticizers with glycerol. RESULTS: The employment of co-plasticizers reduced the melt fluidity of the blends, established intermolecular hydrogen bonds with starch and resulted in a brittle film structure. The presence of sucrose contributed to the formation of more B-type starch crystals. Glucose and sucrose promoted the conversion of bound water to entrapped water, while sorbitol contributed to more bound water. The co-plasticizers enhanced films' thermal stability, moisture permeability (from 3.61 to 3.72 × 10-11 g m m-2 s-1 Pa-1), and oxygen barrier (from 12.84 to 8.74 × 10-13 cm3 cm cm-2 s-1 Pa-1). Glucose/glycerol co-plasticized film had the maximum tensile strength (10.12 MPa), and sucrose/glycerol co-plasticized film showed the highest Young's modulus (380.31 MPa). CONCLUSION: Sorbitol with linear structure and the lowest melting point exhibited a plasticizing capacity similar to glycerol. The molecular structure (linear or cyclic), hydroxyl group proportion and melting point of the sugar/sugar alcohol were the key factors to regulate the fine structure and properties of starch/PBAT films. © 2024 Society of Chemical Industry.

Optimization of Phosphotyrosine Peptides that Target the SH2 Domain of SOCS1 and Block Substrate Ubiquitination.

Suppressor of cytokine signaling 1 (SOCS1) has emerged as a potential therapeutic target in inflammatory and viral diseases. SOCS1 operates via its kinase inhibitory region, Src homology 2 (SH2) domain, and SOCS box to negatively regulate the Janus kinase/signal transducers and activators of transcription signaling pathway. In this study, we utilized native phosphotyrosine peptide substrates as a starting point to iteratively explore the requirement of each amino acid position to target the SH2 domain of SOCS1. We show that Met, Thr, Thr, Val, and Asp in the respective -1, +1, +2, +3, and +5 positions within the peptide substrate are favored for binding to the SOCS1-SH2 domain and identifying several phosphotyrosine peptides that have potent SOCS1 binding affinity with IC50 values ranging from 20 to 70 nM and greater than 100-fold selectivity against the closely related SOCS family proteins, CIS, SOCS2, and SOCS3. The optimized phosphotyrosine peptide was shown to stabilize SOCS1 in a thermal shift assay using cell lysates and inhibited SOCS1-mediated ubiquitination of a target substrate in a biochemical assay. Collectively, these data provide the framework to develop cell-permeable peptidomimetics that further investigate the potential of the SOCS1-SH2 domain as a therapeutic target in inflammatory and viral diseases.

Mitochondria-targeting BODIPY-loaded micelles as novel class of photosensitizer for photodynamic therapy.

In this paper, a series of novel BODIPY-based photosensitizers have been designed and synthesized for photodynamic therapy. BODIPY3 was screened out as the most potential photosensitizer due to its excellent optical properties, high singlet oxygen efficiency and good photostability. However, as an organic photosensitizer, BODIPY3 still suffered from the drawbacks of insolubility and instability in aqueous system. In view of these problems, DSPE-PEG2000 was used to trap BODIPY3 into the hydrophobic core of micelles to obtain well-dispersing nano complexes BODIPY3-PEG3 in aqueous system. More importantly, BODIPY3-PEG3 not only has better solubility and stability in aqueous media but can generate significant singlet oxygen (1O2, one of the reactive oxygen species, the real cytotoxic agent in photodynamic therapy) in living cells and exhibit high light cytotoxicity to three cancer cell lines. The mechanism studies indicated the mitochondrial localization of BODIPY3-PEG3 was able to generate ROS in mitochondria, which further result in mitochondrial dysfunction and photoinduced apoptosis via caspase-8 and caspase-3 pathway.