Chitosan with Aloevera

What is Chitosan ?

Chitosan is a product obtained from Chitin which is the main structural unit and found in abundance in the shells of crustacean such as crabs, lobsters, prawns, insects and also in the cell walls of certain fungi. Sea food processing industries are/can be, the source of Chitin.

Renewable chitin in produced in nature at a level of up to 1×10⁹ to 1×10¹⁰ tones per year

Properties:

• Chitosan has properties including, anti-microbial activity, bio-compatibility, low-allergen, high moisture retention and is completely harmless to humans.
• Chitosan has been shown to be effective even agaisnt MRSA
• Bio de-gradable
• Chitosan is extremely safe and non-toxic.
• Chitosan films interact comfortably with the human body
• Chitosan is produced commercially by deacetylation of chitin

Chitosan… an antimicrobial

The results obtained from a piece of treated fabric specimen against Staphylococcus Aureus according to testing method AATCC147.

As can be seen the treated sample shows good antibacterial properties even after 50 washes.

Notes on Chitosan

Chitosan is a linear polysaccharide [a carbohydrate (e.g. starch or cellulose) whose molecules consist of chains of sugar molecules] whose , polysaccharide is composed of randomly distributed β-(1-4)-linked D-glucosamine (deacetylated unit) and N-acetyl-D-glucosamine (acetylated unit).

Chitosan is produced commercially by deacetylation of chitin , which is the structural element in the exoskeleton of crustaceans (crabs, shrimp, etc.) and cell walls of fungi.

An important property of chitosan is its positive charge in acidic solution. This is due to the presence of primary amines on the molecule that binds protons according to the equation:

The pka value for the equation is approximately 6.3. Chitosan solubalizes when more than 50% of the amino groups are protonated, so the solubility of most chitosan preparations decreases sharply the solution ph rises above 6.0 – 6.5. The maximum soluble concentration varies with different chitosan, but is usually around 10 – 20gm/L.

Notes on Antimicrobial Activity

• Chitosan is antimicrobial against a wide range of target organisms. Activity varies considerably with the type of Chitosan, the target organism and the environment in which it is applied.
• Yeasts are the most sensitive group, followed by Gram-positive bacteria and experimental work with the baker’s yeast Saccharomyces Cerevisiae showed that fermentation was halted as little as 3.6 mg/L chitosan in buffer system.
• Moulds are the most sensitive group, followed by Gram-negative bacteria and a powerful activity has been demonstrated against the mould Fusarium Solani, the growth of which was prevented by 4mg/L chitosan in liquid nutrient medium.
• It has been demonstrated that lower molecular weights (of less than 10 kDa) have greater antimicrobial activity than the native chitosan. However, a degree of polymerization of at least 7 is required; lower molecular weight fractions have little or no activity.
• Highly deacetylated chitosans are more antimicrobial than those with a higher portions of acetylated amino groups, due to increased solubility and higher charge density.
• Lower pH value increase the antimicrobial activity of the chitosan
• Higher temperature (37°C, the human body temperature) has been shown to enhance the antimicrobial activity compared to refrigeration temperatures.
• Chitosan being cationic, has the potential to bind to many components, such as alginates, pectin, proteins and inorganic polyelectrolytes such as polyphosphate. Solubility can be decreased by using high concentrations of low molecular weight electrolytes such as Sodium Halides, Sodium Phosphate, organic anions.