RESUMO
objective:To prepare a composite photocrosslinked hydrogel containing zeolite imidazole framework-8(ZIF-8),and to evaluate its in vitro cytotoxicity,drug release capability,and antimicrobial propertie.Methods:The ZIF-8 particles were synthesized by hydrothermal method,and the microstructure characteristic was observed under scanning electron microscope(SEM).The particles were mixed with the gelatin methacryloyl(GelMA)with the mass fraction of 0.2%to obtain the composite hydrogel GelMA-Z.The atomic absorption spectroscope was used to detect the cumulative zinc ion(Zn2+)release amounts in GelMA-Z at different time points.The NIH-3T3 cells were co-cultured with GelMA-Z for 1,3,and 7 d;the viabilities of the cells in various groups were detected by CCK-8 assay;the GelMA-Z was co-cultured with Escherichia coli(E.coli)and Staphylococcus aureus(S.aureus)for 6,12,and 24 h and divided into control group,GelMA group,and GelMA-Z group.The bacterial activities of the cells in various groups at different time points were detected by microplate reader;the bacterial formation and the presence of live/dead becterial staining condition were detected by plate antibacterial experiment and live/dead bacterial staining method.Results:The SEM observation results showed that the hydrothermally synthesized ZIF-8 particles had the uniform particle sizes.The atomic absorption spectroscope results showed that Zn2+ in GelMA-Z showed an initial burst phase within 1 d,followed by a slow release,and reached the equilibrium around 7 d.Compared with control group,the viabilities the cells in GelMA group and GelMA-Z group were above 90%on the 1st,3rd,and 7th days,but there was no significant difference(P>0.05).The bacterial activity detection results showed that when co-cultured with bacteria for 6,12,and 24 h,compared with control group and GelMA group,the bacterial activities of the E.coli and S.aureus in GelMA-Z group were decreased(P<0.05).The plate antibacterial experiment results showed that the number of bacterial formation in GelMA-Z group was fewer than those in control group and GelMA group.The live/dead bacterial staining results showed that in GelMA-Z group,there was a large number of red fluorescence stained dead bacteria;in control group and GelMA group,there was a large number of green fluorescence stained live bacteria.Conclusion:The GelMA hydrogel loaded with ZIF-8 particles can achieve the in situ photocrosslinking and possesses good Zn2+ release capability and antimicrobial activity,and it is a novel hydrogel dressing for treatment of the infected wounds.
RESUMO
Stem cells have been regarded with promising application potential in tissue engineering and regenerative medicine due to their self-renewal and multidirectional differentiation abilities. However, their fate is relied on their local microenvironment, or niche. Recent studied have demonstrated that biophysical factors, defined as physical microenvironment in which stem cells located play a vital role in regulating stem cell committed differentiation. In vitro, synthetic physical microenvironments can be used to precisely control a variety of biophysical properties. On this basis, the effect of biophysical properties such as matrix stiffness, matrix topography and mechanical force on the committed differentiation of stem cells was further investigated. This paper summarizes the approach of mechanical models of artificial physical microenvironment and reviews the effects of different biophysical characteristics on stem cell differentiation, in order to provide reference for future research and development in related fields.