The green and facile synthesis of metallic silver nanoparticles (AgNPs) is getting tremendous attention for exploring superior applications because of their small dimensions and shape. AgNPs are already proven materials for superior coloration, biocidal, thermal, UV-protection, and mechanical performance. Originally, some conventional chemical-based reducing agents were used to synthesize AgNPs, but these posed potential risks, especially for enhanced toxicity. This became a driving force to innovate plant-based sustainable and green metallic nanoparticles (NPs). Moreover, the synthesized NPs using plant-based derivatives could be tuned and regulated to achieve the required shape and size of the AgNPs. AgNPs synthesized from naturally derived materials are safe, economical, eco-friendly, facile, and convenient, which is also motivating researchers to find greener routes and viable options, utilizing various parts of plants like flowers, stems, heartwood, leaves and carbohydrates like chitosan to meet the demands. This article intends to provide a comprehensive review of all aspects of AgNP materials, including green synthesis methodology and mechanism, incorporation of advanced technologies, morphological and elemental study, functional properties (coloration, UV-protection, biocidal, thermal, and mechanical properties), marketing value, future prospects and application, especially for the last 20 years or more. The article also includes a SWOT (Strengths, weaknesses, opportunities, and threats) analysis regarding the use of AgNPs. This report would facilitate the industries and consumers associated with AgNP synthesis and application through fulfilling the demand for sustainable, feasible, and low-cost product manufacturing protocols and their future prospects.

Effect of Different Nanoparticle Treatments on the Decay Resistance of Wood

The present paper studied the chemical composition of recent and historical oak wood comparing the extractive, holocellulose, α-cellulose, lignin, and ash contents. Comprehensive knowledge of the chemical components in recent and historical oak wood will facilitate the use of conservation agent in the restoration and conservation process of the investigated artifacts. The cyclohexane–ethanol extract of historical oak wood was significantly lower compared to recent wood, which can be explained by the leaching of extractives into the soil. No significant differences in the holocellulose and α-cellulose content of recent and historical oak wood were found. The lignin and the ash contents were significantly higher in the historical samples. The EDX analysis of the ash of historical oak wood showed remarkably higher iron content compared to the recent material. The result indicated the degradation of hemicelluloses in the historical sample. The significant difference in the amount of ash between the samples was explained by sediment materials that have been introduced into the wood from the soil. SEM imaging made these materials clearly visible as depositions in the cell lumens.

The reinforcement of natural and artificial fiber-oriented woven fabrics with thermosetting polymers is getting popularity nowadays. The hybridization of natural hemp with glass could facilitate the developed composite panels to be a potential candidate for automotive parts. Both hemp and glass-woven fabrics were treated with greenly synthesized silver nanoparticle (AgNPs) obtained from Tilia cordata leaf extracts and then composited by using thermosetting epoxy resin. Three composite panels were developed from five consecutive layers of glass- and hemp-woven fabrics (sequence is glass, hemp, glass, hemp, glass); in two of them the fabrics were loaded with 1% and 5% AgNPs, respectively, the third one was prepared without any nanosilver loading. The presence of green AgNP was tested and confirmed by using XRF (X-ray fluorescence) and ICP OES (inductively coupled plasma optical emission spectroscopy) test. The developed hybrid composites were characterized for thermal, mechanical, physical, and morphological performance and found satisfactory results. Statistical analysis of the test results also confirmed the positive influence of nanosilver loading on hybrid composites. However, the developed biocomposite panels could facilitate the industrial production units with most advanced, feasible, and multi-functional laminated products. Graphical Abstract

The improving effect of nanoparticles on wood dimensional stability is barely known nowadays. The expected result of the research was the improvement of the dimensional stability through bulk hydrophobization, as a result of impregnation with hydrophobic SiO₂ nanoparticles. Two different wood species, beech (Fagus sylvatica) and scots pine (Pinus sylvestris) were investigated. Two different treatments with silica nanoparticles were used. One treatment was a pure emulsion of modified (hydrophobized) silica nanoparticles (carrier material: ethanol), and another one was modified (hydrophobized) silica nanoparticles in tetrahydrofuran carrier material in combination with polydimethylsiloxane (PDMS) as a bonding agent. PDMS was used to improve the bonding of the silica nanoparticles to the wood structure. The impregnation with nanoparticles was successful. Shrinking and swelling properties decreased by 17–33%, depending on wood species and treatment. Water uptake and equilibrium moisture content decreased significantly as a result of the treatments (40–58%). Application of PDMS did not provide better dimensional stability compared to the treatment without it, however, it resulted in lower equilibrium moisture content and water uptake compared to the basic nano-SiO₂ treatment.