Poly(vinyl alcohol)/sodium alginate polymer membranes as eco-friendly and biodegradable coatings for slow release fertilizers.

BACKGROUND: The use of slow release fertilizers (SRFs) is an effective approach for reducing agriculture cost, environmental and ecological issues simultaneously. The present study provides a series of poly(vinyl alcohol) (PVA)/sodium alginate (SA) polymer membranes as eco-friendly and biodegradable coatings for SRFs. Moreover, polymer-coated urea (PCU) granules were fabricated through coating the urea granules with the resulting membranes. Our first interest was to fabricate three membranes (PS1, PS2, PS3) of different PVA/SA weight ratios (9:1, 8:2, 7:3) using glutaraldehyde as a crosslinking agent, and crosslink the PS3 membrane with a CaCl2 solution further to obtain the PC3 membrane. The chemical properties and morphologies of the membranes were characterized. Second, the nitrogen release behavior of the PCU granules was measured and calculated, respectively. RESULTS: Crosslinking with glutaraldehyde made the PS1, PS2, PS3 membranes uniform and compact, whereas crosslinking with a CaCl2 solution formed an 'egg box' structure inside the PC3 membrane. PS3 membrane with the minimum PVA/SA weight ratio had the highest hydrophily (water uptake: 106.25%, water contact angle: 55.1o ), whereas PC3 membrane had the lowest hydrophily (water uptake: 21.57%, water contact angle: 67.3o ). The biodegradation ratios of the membranes were in the range 44-60% in 90 days, indicating that they had excellent biodegradability. The measured fractional release on the day 30 of the PCU granules ranged from 89.33% to 97.07%. The calculated nitrogen release behavior agreed well with the measured values. CONCLUSION: The resulting eco-friendly and biodegradable PVA/SA membranes are alternative coatings for SRFs. © 2022 Society of Chemical Industry.

Simultaneous leaching of multiple heavy metals from a soil column by extracellular polymeric substances of Aspergillus tubingensis F12.

The use of the biological agents for leaching heavy metals from contaminated soils is a very promising method that is both efficient and eco-friendly. In this study, a fungus Aspergillus tubingensis F12 was reported to possess a strong adsorption capacity for various heavy metal ions and shown to adsorb 90.8% Pb, 68.4% Zn, 64.5% Cr, 13.1% Cu, 12.9% Ni, and 6.9% Cd in aqueous solution. As extracellular polymeric substance (EPS) was found to play a leading role in the adsorption of metal ions, we applied EPS as a leaching agent to simultaneously remove six metals from soil in a column leaching experiment. The flow rate, initial solution pH, initial EPS concentration, and ionic strength were investigated using response surface methodology. The minimum and maximum metal leaching capacities were determined to be 0.089 mg/g and 3.703 mg/g, respectively. Verified by Fourier transform infrared spectroscopy, scanning electron microscope energy dispersive X-ray spectroscopy, and X-ray photoelectron spectroscopy, we made the preliminary deductions that ion exchange determines the leaching capacity limit and that biosorption plays a large role in reaching that limit. Additionally, the redox behaviour of Cu produced more carboxyl groups, which increased the adsorption of heavy metals. The ecological impact of this method was also examined; we found that the influences of leaching with EPS on soil properties and microbial community structure were slight. Therefore, the reported leaching process might have application prospects for metal removal from soil.

Knockdown of TBRG4 suppresses proliferation, invasion and promotes apoptosis of osteosarcoma cells by downregulating TGF-ß1 expression and PI3K/AKT signaling pathway.

Transforming growth factor beta regulator 4 (TBRG4) is a novel regulator in tumorigenic progression of several tumors. However, so far, the expression and functions of TBRG4 in osteosarcoma are unknown. The aim of this study was to investigate the potential biological functions of TBRG4 in osteosarcoma. Quantitative real-time polymerase chain reaction (qRT-PCR) was used to detect the expression of TBRG4 in osteosarcoma tissues and cell lines. The levels of TBRG4 protein in osteosarcoma tissues were assessed by immunohistochemistry. Lentivirus-mediated short hairpin (sh) RNA was employed to knock down TBRG4 in osteosarcoma cells, and the expressions of TBRG4 mRNA and protein were determined by qRT-PCR and Western blot assay, respectively. Subsequently, the proliferation, clonogenic ability, apoptosis and invasion of osteosarcoma cells were measured using high content screening analysis and CCK8 assay, tumor sphere formation assay, flow cytometry and Transwell invasion assays, respectively. Furthermore, the osteosarcoma cells growth and metastasis in vivo were detected, and the effect of TBRG4 on the transforming growth factor ß1 (TGF-ß1) and PI3K/AKT signaling pathway was explored by qRT-PCR and Western blot assay, respectively. The results showed the levels of TBRG4 were overexpressed in osteosarcoma tissues and cell lines, confirming that the high TBRG4 expression was related to advanced tumor stages, large tumor size, and lymph node metastasis. Functional assays showed knockdown of TBRG4 could inhibit proliferation, invasion and induce apoptosis of osteosarcoma cells in vitro, and could also suppress osteosarcoma growth and metastasis in vivo. By examining the expression levels of TGF-ß1, p-PI3K, PI3K, p-AKT and AKT, it showed that the suppression of TBRG4 would reduce TGF-ß1 expression and inactivate the PI3K/AKT signaling pathway. These results showed for the first time that TBRG4 knockdown could suppress osteosarcoma progression, suggesting TBRG4 might be a promising therapeutic target for osteosarcoma treatment.