Construction of tea tree oil/salicylic acid/palygorskite hybrids for advanced antibacterial and anti-inflammatory performance.

This study describes the construction of a tailor-made clay-based hybrid with advanced dermocompatibility, antibacterial and anti-inflammatory performance by incorporating tunable ratios of tea tree oil (TTO) and salicylic acid (SA) into the naturally occurring porous structure of palygorskite (Pal). Among the three TTO/SA/Pal (TSP) systems constructed, TSP-1 with a TTO : SA ratio of 1 : 3 demonstrated the lowest 3T3 NRU predicted acute oral toxicity and dermal HaCaT cytotoxicity as well as the most pronounced antibacterial activity with a selective inhibitory action against the pathogens (E. coli, P. acnes and S. aureus) over the beneficial (S. epdermidis) species inhabiting on the human skin. Also noticeable is that exposure of these skin commensal bacteria to TSP-1 prevented the antimicrobial resistance evolution compared to the conventional antibiotic ciprofloxacin. Mechanistic investigation of its antibacterial modes of action revealed a synergy between the TTO and SA loadings on the Pal supports in reactive oxygen production, causing oxidative damage to bacterial cell membranes and increased leakage of intracellular compounds. Additionally, TSP-1 significantly decreased the proinflammatory cytokines of IL-1ß, IL-6, IL-8, and TNF-α in a bacterial lipopolysaccharide-stimulated differentiated THP-1 macrophage model, showing the potential to inhibit inflammatory responses in bacterial infections. Overall, this is the first report exploring the potential of constructing clay-based organic-inorganic hybrids as alternatives to antibiotics to combat bacterial resistance with advanced compatibility and anti-inflammatory benefits that are desired for the development of topically applied biopharmaceuticals.

[Effects of Chemical Fertilizer Reduction Substitute with Organic Fertilizer on Soil Functional Microbes and Lemon Yield and Quality].

To clarify the effects of non-rhizosphere/rhizosphere soil functional microbes (nitrifiers, denitrifiers, and phosphorus-solubilizing microorganisms) on lemon yield and quality, the lemon fruit and non-rhizosphere/rhizosphere soil were selected as subjects. To explore the correlation between non-rhizosphere/rhizosphere soil functional microbes and lemon yield and quality under a chemical fertilizer reduction substitute with organic fertilizer, traditional fruit quality determination and multiple molecular techniques were used. The results showed that:① 30% chemical fertilizer reduction substitute with organic fertilizer increased the nitrification intensity and phosphatase activity but effectively controlled the denitrifying enzyme activity. ② The chemical fertilizer reduction substitute with organic fertilizer significantly decreased the abundances of nitrifiers and nirS/nirK-harboring denitrifiers and significantly increased the abundances of nosZ-harboring denitrifier and phoD-harboring microorganisms. However, the diversities of functional microbial community structure did not have clear regularity under chemical fertilizer reduction substitute with organic fertilizer. ③ Compared with that under the application of chemical fertilizer and organic fertilizer alone, lemon yield and quality were the highest under the 30% reduction of chemical fertilizer substitute with organic fertilizer. ④ Nitrogen and its related microbes significantly affected lemon yield through internal and external quality. Phosphorus and its related microbes affected lemon yield mainly through internal quality. In addition, the influence factors of non-rhizosphere soil and rhizosphere soil on lemon intrinsic quality were obviously different. Altogether, these results showed that the 30% reduction of chemical fertilizer substitute with organic fertilizer significantly affected soil nitrogen and phosphorus functional microorganisms and further improved lemon yield and quality.

[Effects of Chemical Fertilizer Reduction Combined with Organic Fertilizer Application on Bacterial Community Structure in Rhizosphere/Non-Rhizosphere Soil of Lemon].

The aim of this study was to examine the effects of different fertilization methods on the physicochemical properties and bacterial community structure of lemon rhizosphere/non-rhizosphere soil in order to provide theoretical basis for scientific and rational fertilization of orchards. A pot experiment was carried out, and six fertilization treatments were set up:control (CK), conventional fertilization (FM), organic fertilizer (P), fresh organic fertilizer (NP), 70% chemical fertilizer+30% organic fertilizer (70FP), and 50% chemical fertilizer+50% organic fertilizer (50FP). Chemical analysis, real-time fluorescence quantitative PCR, and terminal restriction fragment length polymorphism (T-RFLP) were used to study the effects of different fertilization treatments on the physicochemical properties of rhizosphere and non-rhizosphere soils, the abundance of the bacterial 16S rRNA gene, and bacterial community structure. Redundancy analysis (RDA) was used to explore the environmental factors affecting the bacterial community structure of lemon rhizosphere/non-rhizosphere soil. The results showed the following:① the pH and contents of organic matter, alkali-hydrolyzed nitrogen, available phosphorus, available potassium, and nitrate nitrogen in rhizosphere/non-rhizosphere soil were significantly increased by reducing the amount of chemical fertilizer and applying organic fertilizer (50FP and 70FP) (P<0.05). Compared with conventional fertilization (FM) and single application of organic fertilizer (P and NP), the soil available P content, available K content, and nitrate nitrogen content increased by 24.76%-97.98%, 6.87%-45.11%, and 18.42%-55.82%, respectively. ② Fertilizer reduction combined with organic fertilizer significantly increased the abundance of soil bacteria and soil respiration intensity (P<0.05), and the abundance of soil rhizosphere bacteria and soil respiration intensity under the 50FP treatment increased by 15.83%-232.98% and 8.0%-162.5% compared with that under conventional fertilization and organic fertilizer alone, respectively. The bacterial abundance of rhizosphere soil was positively correlated with the pH and contents of organic matter, total nitrogen, and total phosphorus. ③ The PCoA and RDA analysis results showed that the single organic fertilizer and organic fertilizer and chemical fertilizer de-weighting of rhizosphere bacterial community structure and not adding fertilizer had a bigger difference between processing, and the main environmental factors influencing the rhizosphere/non rhizosphere bacterial community structure were organic matter, total nitrogen, total phosphorus, total potassium, alkali solution nitrogen, nitrate nitrogen, and available potassium. Fertilizer reduction combined with organic fertilizer could significantly increase soil nutrient content, increase soil bacterial abundance, and change the bacterial community structure of rhizosphere soil, and the 50FP treatment yielded better results. Therefore, 50% Chemical fertilizer+50% organic fertilizer (50FP) was a better fertilization method to improve the physical and chemical properties of orchard soil, increase the abundance of soil bacteria, and improve the soil respiration intensity.

Fibrous Clays in Dermopharmaceutical and Cosmetic Applications: Traditional and Emerging Perspectives.

Functionalization of natural clay minerals for high value-added pharmaceutical and cosmetic applications receives significant research attention worldwide attributable to a rising demand and ongoing search for green, efficient, economically sustainable and ecofriendly geomaterials. Fibrous clays, i.e. palygorskite and sepiolite, are naturally-occurring hydrated magnesium aluminum silicate clay minerals with 2:1 layer-chain microstructure and one-dimensional nanofibrous morphology. Due to their unique structural, textural and compatibility features, over the past decade, fibrous clays and their organic modified derivatives are increasingly used in the dermopharmaceutical and cosmetic fields as excipients, active agents or nanocarriers to develop novel skin delivery systems or to modify drug release profile for enhanced health effects. This comprehensive review presents the up-to-date information on fibrous clays used in topically-applied products for therapeutic and cosmetic purposes with the focus on their performance-related structural characteristics and the underlying mechanisms. The recent advancement of fibrous clay-based skin delivery systems was summarized in wide range of applications including pelotherapy, wound healing, antimicrobial action, coloration and UV protection. An overview of the commonly used topically-applied dosage forms (powders, hydrogels, films, peloids and Pickering emulsion) as well as the toxicological aspects was also included, which might provide guidance to the design and development of fibrous clay-based skin delivery systems.

Fibrous palygorskite clays as versatile nanocarriers for skin delivery of tea tree oils in efficient acne therapy.

This paper presents a facile approach to develop palygorskite (Pal), a fibrous clay mineral, as a delivery system of tea tree oil (TTO) for topical acne therapy. The obtained TTO-Pal composite showed an efficient loading of TTO (27.4%) with a selective accumulation of terpine-4-ol and 1,8-cineole (two major antimicrobial TTO constituents), sustained release of TTO at skin physiological conditions (pH5.4, 32 °C) and superior skin sebum (2.2 g/g) absorbability. In vitro toxicological assessments showed that the Pal incorporation strategy significantly reduced the acute contact toxicity of TTO. The antimicrobial results revealed a preferable bacteriostatic effect for the TTO-Pal system towards opportunistic dermal pathogens (Escherichia coli, Staphylococcus aureus and Propionibacterium acnes) over the beneficial bacterium (Staphylococcus epidermis). Moreover, TTO-Pal based formulations exhibited pronounced clinical therapeutic efficacy in treating facial acne by rapidly reducing inflamed lesions, modulating skin sebum overproduction and restoring barrier function. This is the first report of using fibrous clay as a biocompatible nanocarrier system for topical delivery of essential oils in efficient management of facial acne with both in vitro and in vivo evidences, which may open perspectives for fibrous clay-drug delivery system in topical application and expand the high added value development of this mineral resource in the advanced healthcare fields.