Low temperature, rapid solution growth of antifouling silver-zeolite nanocomposite clusters

• Low temperature synthesis of Ag-zeolite (AgZ) nanocomposite clusters.
• Zeolite structure preserved with high Ag loading (10 wt% Ag).
• Static biofilm assay on Halomonas pacifica, common marine biofilm forming bacteria.
• Higher biofilm inhibition with higher Ag loading.
• Up to 81% decrease of biofilm attachment for AgZ with 10 wt% Ag loading.

Biofouling is a common and pervasive problem which reduces the efficiency of man-made marine structures. Silver-zeolite (AgZ) nanocomposite material is proposed as a promising anti-microfouling agent. Metallic silver nanoparticles were immobilized on silver ion doped ZSM-5 zeolites using a green reducing agent, trisodium citrate. The stable and porous inner structure of ZSM-5 zeolites performs a dual role as a stable size-control template and a reservoir of antimicrobial nanosilver. SEM revealed the globular and cluster-like morphology of the AgZ composites, with a homogenous distribution of silver particles on the surface of the AgZ clusters, while TEM analysis indicated Ag nanoparticles could be detected both on the surface and within the zeolite. UV–visible analysis on AgZ displayed the characteristic surface plasmon resonance absorption maximum for Ag nanoparticles ranging from 408 to 500 nm. Indeed, BET analysis also showed a reduction in surface area of up to 44% with the incorporation of Ag nanoparticles into the zeolite, indicating the formation and growth of Ag within ZSM-5 zeolite. XRD analysis indicated the presence of metallic Ag while the ZSM-5 crystalline framework remained largely intact after the Ag crystal growth process. The AgZ nanocomposites were evaluated for their biofilm inhibition activity against Halomonas pacifica, a common marine bacterium implicated in the early stages of biofouling. AgZ loaded with up to 10 wt% Ag reduced biofilm attachment by 81%, and inhibited the growth of marine microalgae Dunaliella tertiolecta and Isochrysis sp. Overall, results demonstrated the effective anti-microfouling property of AgZ nanocomposites.

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