Surface modification of Ti6Al4V based on ultrasonic surface rolling processing and plasma nitriding for enhanced bone regeneration

Titanium alloy has been widely used in dentistry, orthopedic surgery and other medical fields. Surface morphology and structure of titanium alloy play an important role in cell adhesion and proliferation. The main purpose of this study is to investigate the biocompatibility and osteogenesis performance of Ti6Al4V modified using ultrasonic surface rolling processing (USRP) and plasma nitriding (PN). The raw materials were nominated as untreated, and the Ti6Al4V samples treated by USRP (with a processing duration of 1 h and 3 h) and PN were named as USRP1, USRP2, USRP1+PN, and USRP2+PN, respectively. The Ti6Al4V samples were characterized by SEM, AFM, and surface profilometer for surface morphology and 3D surface topography, and USRP1+PN showed the highest surface roughness (268 nm). The water contact angle measurements demonstrated that USRP2 had more favorite wettability (75.7°). The XRD analysis indicated the enhancement of nanocrystallization for the samples treated by USRP and the formation of a nitride layer for the samples treated by USRP and PN. The interactions between the Ti6Al4V samples and MC3T3-E1 cells were investigated in vitro by SEM, CCK-8 test, alkaline phosphatase (ALP) activity assay, and Alizarin Red S staining. The SEM images and CCK-8 tests revealed that all the Ti6Al4V samples were biocompatible to MC3T3-E1 cells, and the results of ALP activity assay and Alizarin Red S staining showed a better osteogenesis performance for the samples treated by USRP and PN. The present study indicates that USRP and PN may act as an effective method for Ti6Al4V to induce bone regeneration.