Rod-shaped keratin nanoparticles extracted from human hair by acid hydrolysis as photothermally triggered berberine delivery system

Abstract Human hair can be a sustainable keratin source to prepare cytocompatible drug nanocarriers. A simple and effective methodology to create rod-like keratin nanoparticles (KNPs) using acidic hydrolysis was reported in this work. The extracted KNPs were characterized by infrared spectroscopy (FTIR), X-Ray diffraction (XRD), thermal analysis (TG and DSC), Zeta potential measurements, scanning electron microscopy (SEM), and transmission electron microscopy (TEM). The KNPs presented an amorphous structure with a smaller average size and higher aspect ratio than KNPs created from previously reported alkaline methods. Furthermore, cell viability assays confirmed that the extracted KNPs are cytocompatible toward adipose mesenchymal stem cells (ADSCs) and healthy cells of the African green monkey (VERO cells). The material was evaluated as berberine (BERB) nanocarrier, a drug with anticancer activity. The BERB was associated with KNPs by adsorption. The rod-shaped KNPs presented a type II adsorption profile toward BERB, adsorbing approximately 168.05 ± 1.44 mg/g. BERB is a cationic species capable of interacting with negatively charged KNPs (Zeta potential equal to −33.8 mV at pH 8.0). After BERB adsorption, the KNPs/BERB Zeta potential is reduced to −10.14 mV (pH 8.0). The KNPs exhibited strong photothermal properties, which improved and enhanced the BERB desorption. The photothermal KNPs responsiveness promoted a sustained BERB release. The KNPs/BERB shows cytotoxity against colon adenocarcinoma cells (HT-29 cells). Therefore, the extracted rod-shaped KNPs can be alternative nanocarriers for BERB delivery.