Antimicrobial activity of 2-mercaptobenzothiazole released from environmentally friendly nanostructured layered double hydroxides

AIMS: The objective of this work was to assess the antibacterial effect of 2-mercaptobenzothiazole (MBT), used as model-biocide, immobilized in a layered double hydroxide (LDH) structure, under different conditions of pH and salinity, envisaging possible applications of the system in active antifouling and anticorrosion coatings. METHODS AND RESULTS: Biological effects of MBT immobilized in LDH were assessed by monitoring bacterial bioluminescence of cell suspensions of either Allivibrio fischeri or a recombinant strain of Escherichia coli, as a proxy for bacterial activity. Salinity (1, 2 and 3% NaCl) and pH (4, 5, 6 and 7) of the suspension media were experimentally manipulated and biocide release tests were performed in parallel. The release profiles obtained by UV-visible spectrophotometry indicated a fast release of biocide from MBT@LDH, slightly enhanced in 3% NaCl and under alkaline conditions. However, biological effects were more pronounced at 1% NaCl and at neutral pH. CONCLUSIONS: The release and toxic effect of MBT immobilized in LDH is dependent on the concentration of solutes in the suspension medium. SIGNIFICANCE AND IMPACT OF THE STUDY: The results confirm LDH as a biologically compatible material with potential to be used for biocide delivery.