Novel antiviral activity of dialdehyde starch

A significant effort worldwide is being directed toward development of novel biocides against drug-resistant bacterial and viruses because of the significant potential human infection risks in the general population. We report here the discovery of a strong antiviral biocide, dialdheyde starch (DAS). Antiviral tests were carried out against three non-envelop viruses, including two bacterial viruses MS2 and PRD1, and one human virus Poliovirus. Dialdehyde starch aqueous suspensions were effective biocides against these three test viruses in a 1 hr exposure test. The antiviral activity was significantly enhanced in a four-hour exposure test, with maximum seven orders of magnitude reductions against MS2 and PRD1, and four-order reduction against Poliovirus. The antiviral activity of dialdehyde starch was found to be pH dependent, being more active in alkaline and acidic conditions than in neutral conditions.

Membrane damage of bacteria by silanols treatment

Antimicrobial action of silanols, a new class of antimicrobials, was investigated by transmission electron microscopy and fluorescent dye studies. Gram-negative bacteria, Escherichia coli and Pseudomonas aeruginosa and Gram-positive bacteria, Staphylococcus aureus and Enterococcus faecalis were treated by silanols at concentration of less than 0.2 wt percent for one hour. Membrane damage of the bacteria by the silanol treatment was clearly observed by transmission electron microscopy. Separation of the cytoplasmic membrane from the outer membrane for E. coli and disorganized cytoplasmic membrane of the Gram-positive bacteria were observed when compared to the control. Fluorescent dyes, green-fluorescent nucleic acid stain (Syto 9) and the red-fluorescent nucleic acid stain (Propidium iodide), were used to monitor membrane damage of the bacteria by Confocal microscopy and Spectrophotometer. A reduction of the green fluorescent emission was detected for silanol treated bacteria indicating membrane damage of the bacteria and supporting the hypothesis that their viability loss may be due to their membrane damage analogus to alcohols.

Silanol - a novel class of antimicrobial agent

Recently, a significant amount of attention has been directed toward development of novel classes of biocides because of the potential for microbial contamination and infection risks to military personnel and in the general population. We have recently discovered a new and unexpected class of powerful biocides based upon compounds derived through simple chemistry from silicone intermediates, "silicon alcohols" called, silanols. One example is trialkylsilanols, R3SiOH. Antimicrobial tests were carried out against Gram-negative bacterium, Escherichia coli, and Gram-positive, Staphylococcus aureus, with silanols, t-butanol, and siloxanes. Trialkylsilanols were very effective biocides against Escherichia coli and Staphylococcus aureus. The number of viable bacteria reduced was more than eight orders of magnitude with silanol treatments. Triethylsilanol, in particular, exhibited a strong antimicrobial effect at a very low concentration within 10 min. These novel biocide silanols can be prepared from low cost intermediates derived from the commercial processesassociated with the silicone industry. Silanols are considered environmentally benign because of their transitory nature and ultimate conversion to CO2, SiO2, and H2O.