Graphene is hydrophobic and cannot be washed off. However, it should be noted that the cotton swab used for nucleic acid detection is a cotton swab stored in a clean and sterile environment without graphene. Sampling cotton swabs are different from those used in daily life, but they do not contain reagents and are less toxic. It should be called "sampling cotton swab" instead of "cotton swab", which is mainly composed of nylon short fiber fluff head and medical-grade ABS plastic rod.