We report a previously unrecognized mechanism for the prolonged action of biocidal agents, which we denote as the zombies effect: biocidally-killed bacteria are capable of killing living bacteria. The concept is demonstrated by first killing Pseudomonas aeruginosa PAO1 with silver nitrate and then challenging, with the dead bacteria, a viable culture of the same bacterium: Efficient antibacterial activity of the killed bacteria is observed. A mechanism is suggested in terms of the action of the dead bacteria as a reservoir of silver, which, due to Le-Chatelier's principle, is re-targeted to the living bacteria. Langmuirian behavior, as well as deviations from it, support the proposed mechanism.

We report a biocidal zombie effect of chlorhexidine, a wide-scope biocidal agent commonly used in disinfectant and antiseptic formulations. The zombie effect refers to the ability of dead bacteria killed by a biocidal agent to act as efficient biocidal agents toward a new generation of viable bacteria. The killed bacteria serve as a reservoir for the antibacterial agent incorporated within them; and the new viable population of bacteria acts as a trap of the bioactive agent, shifting the equilibrium of this agent between the reservoir in the dead cells and their aqueous environment. This report is a major generalization of the zombie phenomenon reported previously for silver from the points of view of extending to organic antibacterial agents; extending the effect to both Gram-negative—Pseudomonas aeruginosa PAO1—and Gram positive—Staphylococcus aureus—representative bacteria; showing that the zombie effect is maintained in the second and third generations; showing the effect to operate in an environment of growth media, which extends it to life-supporting environments; and proving that cross-killing is possible, that is, killed S. aureus cells fully inactivated viable P. aeruginosa.

Entrapment of chlorhexidine within antibacterial copper leads to the formation of a metal composite, whose bactericidal activity exceeds that of silver and that of its individual components. Since the cost of copper is by far lower than that of silver, high volume applications become more accessible.

Major attention has been given to safety, environmental, and health hazard issues which arise from using toxic inorganic colorants and pigments in ceramic and glass technologies. A safe alternative is presented, wherein organic colorants approved for human use are entrapped within sol–gel aluminosilicate hybrid matrices and used for glazing porcelain ceramic and glass substrates. Among the colorants used are brilliant blue FCF replacing the toxic cobalt blue, curcumin replacing the toxic cadmium sulfide yellow, and a mixture of carmine and allura-red replacing the toxic cadmium selenide red. Additional advantages of the proposed approach are lowering of energy consumption, offering convenient and efficient recyclability of the colored glasses (thus also solving the current requirements for color-classified recycling), offering a huge library of thousands of organic colorants, opening for the artist and product designer a wide range of visual effects, and opening new artistic coloration methods to be explored. Full characterization was carried out including UV-vis spectroscopy, photoluminescence, topographic thickness analysis, wettability, SEM and XRD analyses, and FIB elemental analyses. The glazes are bright, of the order of 250 microns thick, crack free, chemically stable, with good adherence to both ceramic and glassy surfaces, and recyclable to the pure colorless ceramics or glass by heating. The potential for artistic applications, is demonstrated.