Nanosilver/hydrogel: Synthesis and application in delaying senescence of cut flower

Abstract

The superabsorbent Aquasorb hydrogel enriched with silver ion solutions was exerted with sodium borohydride (NaBH4) and glucose/ sodium hydroxide (NaOH) in various concentrations as reducing agents. Scanning electron microscopy (SEM), and transmission electron microscopy (TEM) images confirmed the presence of silver nanoparticles (SN) in the amorphous structure of hydrogel. The results showed that the swelling of hydrogel increased by glucose (5 mM) / sodium hydroxide (10 mM) 298.5 g water/g hydrogel, while atomic absorption analysis showed that the amount of SN (0. 1054 mg/ mg hydrogel) was in the reduced sample by glucose (10 mM)/ sodium hydroxide (10 mM). The highest antibacterial activity on Escherichia coli and Bacillus cereus was observed in reduced samples by NaBH4. Then the efficacy of this sample containing SN 1–3 nm sized particles (50 mg L−1) was evaluated in the preservative solution of rose cut flower cv. ‘Red Alert’. The results indicated positive effects of hydrogel enriched with silver nanoparticles on relative fresh water, membrane stability index, and the vase life extended (14.26 days) in cut flowers, and did not result in any evident toxic effects, so that the highest chlorophyll content was observed in the hydrogel containing silver nanoparticles (86.4%). The results indicated that the expression level of two senescence-associated genes (RhAA and RhCG) were decreased in rose petals, and the RhCTR1 as a negative regulator in the ethylene signaling pathway was induced at higher levels in the hydrogel- containing SN treatment. As our findings showed, the nanocomposite hydrogel containing silver nanoparticles can be used to control the toxicity of SN in the preservative solution with higher efficiency, and the ability to use multiple times for senescence delay in the cut flowers industry.