Cashew-gum-based silver nanoparticles and palygorskite as green nanocomposites for antibacterial applications

Yang

et al. 2022

ACS Appl. Bio Mater.

The carrier performance of palygorskite (Pal) can be significantly affected by its structure, morphology, and activity, which was regulated by controlling the dissolution degree of the metal-oxygen octahedron of raw Pal (RPal) under the action of oxalic acid (OA) in this study. The RPal and OA-leached RPal (OPal) then served as supports for immobilizing silver nanoparticles (AgNPs) to form RPal/AgNPs and OPal/AgNPs antibacterial nanocomposites. The structural and morphological characterizations were used to confirm the dispersion uniformity of AgNPs on the RPal and OPal nanorods, and antibacterial experiments were conducted to evaluate the performance of as-prepared composites and also investigate their antibacterial mechanism. The results showed that OPal-48h (OA leaching for 48 h) loaded with AgNPs (OPal-48h/AgNPs) possesses the most excellent and broad-spectrum antibacterial properties, where its minimum inhibitory concentration values against E. coli, S. aureus, ESBL-E. coli, and MRSA reached 0.25, 0.125, 0.25, and 0.5 mg/mL, respectively, which are mainly attributed to the optimal balance between surface activity and structural stability of OPal-48h that maximally increased its dispersibility and active sites, therefore contributing to the in situ formation of monodisperse AgNPs on the nanorods of OPal-48h.

Section: Xrd Analysissupporting

confidence: 88%

“…Many mature methods have been used to load AgNPs onto the surface of Pal, including pyrolysis of metal salts, green methods, and so on. Among all the methods, the metal salt pyrolysis method is the simple and efficient one, due to its advantages of not needing solvents and being able to synthesize the required nanomaterials in situ .…”

Section: Introductionmentioning

confidence: 99%

Structural Evolution of Palygorskite as the Nanocarrier of Silver Nanoparticles for Improving Antibacterial Activity

Yang

et al. 2022

ACS Appl. Bio Mater.

“…Pillai et al [28] obtained AgNPs ranging from 8-10 nm when montmorillonite was used as a support, particles much larger than the average particle sizes obtained in this study. Araujo et al [37] found that palygorskite also yielded large AgNPs (5.5-8.94 nm), similar to those in this study. Dong et al [38] tested the antimicrobial activity of different-sized NPs (10 nm, 30 nm, 60 nm, and 90 nm) and observed that smaller-sized AgNPs (10 nm and 30 nm sized particles) produced lower minimum inhibitory concentrations when tested against V. natriegens.…”

Section: Synthesis and Characterization Of Nanosilver Clay Compositessupporting

confidence: 91%

Antifungal Properties of Nanosilver Clay Composites Against Fungal Pathogens of Agaricus bisporus

Ramakutoane,

Roux‐van der Merwe,

Badenhorst

et al. 2023

ChemistrySelect

This study aimed to determine the possible control of selected pathogenic and competitive fungi of A. bisporus by three nanosilver clay composites and establish the effective concentrations of the composites for inhibiting pathogens. Nanosilver (AgNPs) clay (zeolite, montmorillonite, and palygorskite) composites were synthesized by a microwave‐assisted surface functionalization technique, and various techniques characterized the products. Zeolite and montmorillonite composites showed uniformly distributed spherical AgNPs with an average size of 3.33 nm and 2.85 nm, respectively, whereas palygorskite presented agglomerated and unevenly distributed AgNPs. The influence of the various composites on 9 fungi, including strains of T. aggressivum f. aggressivum, L. fungicola, C. dendroides, and Mycogone sp., was determined in vitro at different concentrations. At 10 mg/mL, AgNP‐zeolite and AgNP‐montmorillonite inhibited 8 out of 9 pathogens, while AgNP‐palygorskite only inhibited 1 pathogen. The nanosilver clay composites tested against A. bisporus revealed no adverse effects on mycelial growth at any concentrations tested. This study confirms that AgNP‐zeolite and AgNP‐montmorillonite composites have effective antifungal properties and can be used as alternative fungicides against mushroom pathogens without affecting A. bisporus growth. However, further investigation is required to unravel the mechanism of selective antifungal activity observed in this study.

“…More recent studies of palygorskite from Guadalupe have investigated its applicability in pharmaceutical industry due to its high specific surface area, bleaching power and maintenance of thixotropic properties in the presence of electrolytes (Araújo et al 2020;Soares et al 2013), and in environmental remediation as an adsorbent of oils, heavy metals and glyphosates (Câmara et al 2020;Simões et al 2017). Other works are related to clay processing techniques to improve its applicability, such as pelletizing, organophilization and acid activation (Furlanetto, Brandão & Bertolino 2018;Novo, Bertolino & Simões 2018;Rodrigues et al 2019).…”

Section: Introductionmentioning

confidence: 99%

Mineralogy of Palygorskite Occurrences from Guadalupe, Piauí, Parnaíba Basin

Pôssa

Bertolino

2022

Anu. Inst. Geociênc.

Palygorskite is a clay mineral with structural units forming ribbons, whose economic importance is directly related to its unusual structure and physicochemical properties, which give it a wide variety of uses in industry. The formation stability field of palygorskite is very limited, which makes deposits of this clay rare around the world. In Brazil, the only exploitable deposits of this mineral are located in the municipality of Guadalupe, Piauí state, inserted in the geological context of the Parnaíba Basin, specifically in the Carboniferous and Permian sequence represented by the Piauí, Poti and Pedra de Fogo formations. The objective of this study was the geological and mineralogical description of palygorskite occurrences in the Guadalupe region. Six occurrences were studied, and 25 samples were collected. These raw samples were processed to concentrate particles with size smaller than 44 µm. XRD, SEM/EDS, density and particle size analysis were performed. Most of the samples were composed of palygorskite, quartz and kaolinite; however, according to the diffractograms, there are three samples with the absence of palygorskite, two with the absence of kaolinite and one with presence of dolomite. From these results, it is possible to correlate hypotheses for palygorskite formation with the local geological context. The environmental conditions of Piauí and Pedra de Fogo formations were favorable to this clay mineral formation, the association of dolomite and palygorskite in an upper layer may indicate a greater association with Pedra de Fogo Formation, however the field descriptions, as the levels of silexite, and the analyses results are not enough to define in which one of these formations the occurrences of palygorskite are inserted.