Investigating the effects of silk fibroin on ultrasound-mediated ultrafine bubble drug transport and delivery systems

Ultrafine bubbles with ultrasound stimuli have recently gained immense attention in developing drug delivery systems. However, research into their construction, stability and the factors influencing this aspect was conducted at the infant stage. This study aimed to utilize silk fibroin (a biocompatible protein extracted from <i>Bombyx mori</i> silkworm) in conjugation with polyethylene glycol 400 to stabilize the ultrafine bubble drug loading and releasing system. Light scattering laser imaging was used to examine the effects of SF and PEG on system stability. In addition, fluorescence laser imaging and optical absorbance measurements were performed to assess the role of these additives in the drug encapsulation and release process. Results confirmed the bubble stability was enhanced by the introduction of SF and PEG into the drug-carrier system. This study demonstrated that the proposed drug-transportation system possessed an encapsulation capacity of more than 80% and a substantial released drug content of up to 50% after the application of ultrasonic radiation.