BACKGROUND: Inert biomaterials such as metal usually hold poor biocompatibility and weak bonding force, which is against the effect of dental or bone implants. Therefore, how to improve their biocompatibility has become the research hotspot.OBJECTIVE: To prepare collagen-coated titanium alloy (Ti6Al4V), and to assess its biocompatibility.METHODS: Ti6Al4V served as the matrix, the 3-amino propyl triethoxy silane (KH550) as the crosslinking agent, and the three-dimensional printed titanium alloy coated by collagen type Ⅰ and Ⅱ was prepared,respectively. The coated materials were co-cultured with mouse preosteoblasts MC-3T3-E1 to evaluate its biocompatibility. The effect of different kinds of collagen on the cell differentiation was compared by differential recognition of surface proteins.RESULTS AND CONCLUSION: When the N content on the titanium alloy surface (Φ10 cm) was 8.41%, the cladding quantity of collagen type Ⅰ and Ⅱ was 0.81 and 0.77 mg, respectively. Compared with the bare titanium alloy, the cell adhered well and distributed extensively on the coated titanium alloy,which showed strong viability and fast proliferation.The cells cultured on collagen type Ⅰ coated materials expressed the proteins associated with matrix synthesis, and those on collagen type Ⅱ coated materials expressed the proteins associated with mineralization. These results clarify that the collagen coating can improve the biocompatibility of titanium alloy, and different types of collagens act on different functional proteins.

ObjectiveTo study the prevalence of depression and the related influencing factors among the frontline healthcare professionals in the prevention and control of risk of imported COVID-19 cases， so as to provide references for improving their mental health status. MethodsBased on Wenjuanxing platform， a total of 984 frontline healthcare professionals participating in the screening and treatment of imported COVID-19 cases in Beijing Xiaotangshan hospital were assessed using Patients’ Health Questionnaire Depression Scale-9 item（PHQ-9）. ResultsA total of 770 questionnaires were collected with a valid rate of 78.3%， among which 344 cases （44.7%） had depressive symptoms. Logistic regression analysis showed that great changes in work content （OR=2.206， P<0.01）， sleep deprivation （OR=2.359， P<0.01）， six hours or less of sleep （OR=2.032， P<0.05）， focusing on epidemic information more than 1 hour per day （OR=1.095， P<0.05） were risk factors for depression， and regular exercise （OR=0.473， P<0.01） was a protective factor for depression relief. ConclusionThe frontline healthcare professionals in the prevention and control of risk of imported COVID-19 cases suffer a high risk of depression， while measures including scientific shift system， adequate sleep， less attention to the epidemic， and regular exercise may be effective in maintaining their physical and mental health.