How Silver Safe Disinfectant works?
Hydrogen peroxide is known for its ability to kill viruses and other pathogens for years now. According to the World Health Organisation (WHO), solutions containing 0.5% hydrogen peroxide (H2O2) can destroy a wide spectrum of bacteria and viruses, including the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), the virus responsible for COVID-19. Silver Safe Disinfectant contains 1% hydrogen peroxide as a minimum.
The addition of silver in Silver Safe Disinfectant range stabilises the solutions by inhibiting catalase, ensuring the long-lasting effects of hydrogen peroxide on surfaces and objects. Additionally, studies have shown that bacteria killed due to silver poisoning can kill other bacteria found in their environment, also known as the “zombies” effect. Therefore, the use of our products suggests that surface will remain active with Silver-Nano particles long after it has been applied.
“Zombies” effect: Silver-killed (zombie) bacteria can kill other bacteria found in their environment
What is the “zombies” effect?
The term “zombies” effect was introduced to describe the ability of silver-killed bacteria to kill other living bacteria found in their environment. This observation was first reported in a 2015 study published in the journal Scientific Reports.
Bactericidal effects of silver?
Silver has been known to exert strong direct bacteriostatic and bactericidal effects for many years; it is also effective against fungi, viruses, and parasites. Notably, silver is being used for the treatment of various conditions or to prevent the transmission of infectious diseases for more than 6000 years now. Despite the advent of antibiotics, silver is still used for the treatment of wound infections, burns, systemic and local infections, and ulcerations.
Over years of research, it has become evident that silver causes cell death via three main mechanisms:
- It creates pores on cell membranes, increasing the permeability of bacterial cells.
- It modulates bacterial metabolism and blocks the respiratory chain. 3. It binds to the DNA, inhibiting bacterial cell division.
The direct antimicrobial effects of silver have been demonstrated in a variety of microorganisms. However, the ability of silver to kill bacterial indirectly has remained unknown until recently.
Discovery of the “zombies” effect?
According to a study conducted at the Hebrew University of Jerusalem, bacteria that died due to silver poisoning can kill other living bacteria found in their environment. This phenomenon was named “zombies” effect, and the findings of this study were published in the journal Scientific Reports in 2015.
The researchers exposed bacteria (Pseudomonas aeruginosa PAO1) to silver. After bacteria were killed by silver, the researchers examined the dead bacteria under an electron microscope and observed the presence of trapped silver particles inside bacterial cells.
Transmission electron microscopy images of E. coli cells before (a) and after (b) treatment with silver, showing accumulation of silver particles in silver-killed cells. Adapted from Scientific Reports 5, Article number: 9555; doi:10.1038/srep09555.
Incubation of dead bacteria with “fresh” living bacteria for 6 hours in a silver-free solution killed 99.99% of the new bacteria – the researchers described this as the “zombies” effect.
Further investigations to identify the cause of death in the fresh bacteria revealed that a low concentration of silver was not sufficient to all of the third bacterial batch, which further supported that the bacteria soaked up the silver particles and suggested that the silver released from the dead bacteria was responsible for the death of other bacteria found in the environment.
Overview of the discovery of the “zombies” effect. Adapted from Scientific Reports 5, Article number: 9555; doi:10.1038/srep09555.
A recent study published in the journal Antibiotics in 2020 confirmed that silver- killed Escherichia coli O104:H4 and its supernatant exerted strong microbicidal effects against fresh living cells of the same bacterium and some other species, including Escherichia coli O157:H7. By electron microscopy, the researchers also confirmed the accumulation of silver particles inside the bacterial cells, which had been previously shown in P. aeruginosa in the 2015 study.
Importantly, silver-killed bacteria were able to kill the multidrug-resistant Pseudomonas aeruginosa and methicillin-resistant Staphylococcus aureus; the antimicrobial effects of silver-killed E. coli O104:H4 lasted for up to 40 days.
How the “zombies” effect works?
The researchers found that silver ions can create holes in bacterial membranes, penetrating and killing bacteria. After dying, these bacteria serve as silver reserves, gradually releasing silver in their environment. Silver released from dead bacteria penetrates and kills other living bacteria, starting the whole process over again; hence, these dead bacterial resemble “zombie” bacteria that kill other bacteria around them.
Implications of the “zombies” effect?
Silver-killed bacteria act as powerful weapons against living microorganisms that are present in their environment. Hence, the killing ability of silver-containing solutions could carry on indefinitely: silver particles accumulate in bacterial cells and then are slowly released by silver-killed bacterial, starting the next cycle of accumulation-kill-release.
This makes our Silver Safe Disinfectant useful for a wide range of applications, providing potent and long-lasting bacteriostatic and bactericidal effects.