Antifungal properties of cellulose nanocrystals and chitosan nanofiber on the banknotes in Iran

The banknotes is one of the most important ways to transfer of the many of microbes to human and also human diseases. These banknotes have several contaminants such as fungi, bacteria, and microbes which can transfer different diseases to human and also make huge problems for health as we as environment. Therefore, the use of proper techniques especially if they were friendly environment and biobased can introduce as suitable suggestion for decreasing the environment contaminants and also healthy concern. So, in this study, the anti-fungal effect of cellulose nanocrystal alone and with chitosan nanofiber on the common paper banknotes has been examined.
Cellulose nanocrystals have been prepared using acid hydrolysis by H2SO4 from cotton linter. Shortly, the cellulose nanocrystal preparation was consist of acid hydrolysis (by using sulfuric acid), centrifuging technique at 16000 rpm, and dialysis process by using cellulose acetate membrane, and naturalizing with distilled water. The diameter of the prepared cellulose nanocrystals and chitosan nanofibers was characterized by transmission electron microscopy (TEM). Firstly, the fungal contamination of the banknotes from four centers (bakery, butchery, passenger terminal and hospital) was evaluated. Then, in order to consider the antifungal activity of cellulose nanocrystals and chitosan nanofiber compound, stable emulsions with 1%, 2%, 4% and 6% concentrations have been prepared and then coated to the surface of banknotes using rolling coating method.
According to the TEM images, the diameter for cellulose nanocrystals and chitosan nanofiber was 5-20 nm and 45 nm, respectively. It can be concluded that the cellulose nanocrystals have been successfully prepared from cotton linter. The results showed most fungal spices found in banknotes from bakery, butchery, passenger terminal and hospital) are Aspergillus, Aspergillus niger and Penicillium respectively. Anti-fungal examination of paper banknotes covered with cellulose nanocrystals at concentration of 3% shows no significant anti-fungal activity on Penicillium fungi on paper banknotes from hospital. In addition, the results also show that adding chitosan nanofiber at 1%, 2% and 4% concentrations has no anti-fungal effect on the surface of banknotes from bakery, butchery, passenger terminal and hospital, but adding chitosan nanofibers at 6% concentration shows significant anti-fungal effect. The results show that cellulose nanocrystals had no antifungal effect alone effect alone on the banknote species, but in could improve the antifungal effect, adhesion, and stability of cellulose nanocrystals on the banknote surfaces.
This study suggested a new approach to decrease the infection spreads through banknotes.