Silk nanoparticles for the protection and delivery of guava leaf (Psidium guajava L.) extract for cosmetic industry, a new approach for an old herb oleh Duy Toan Pham, Doan Xuan Tien Nguyen, Ruby Lieu, Quoc Cuong Huynh, Ngoc Yen Nguyen, Tran Thi Bich Quyen, Van De Tran