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Cellulose nanofibrils (CNF) is considered as an inexhaustible precursor to produce antibacterial materials, such as antibacterial hydrogel, antibacterial paper, and antibacterial film. However, the poor antimicrobial property of neat CNF required it should be coupled with an antibacterial ingredient. Herein, biocompatible Au nanoclusters (AuNCs) were synthesized and added into the CNF dispersion to prepare a novel antibacterial film (AuNCs@CNF film). The effects of addition of AuNCs with different amount on the morphology and physicochemical properties of AuNCs@CNF films were characterized using atomic force microscopy (AFM), scanning electron microscopy (SEM), X-ray diffraction (XRD), FTIR (Fourier-transform infrared), light transmittance spectra, and thermogravimetric analysis (TGA). The results showed that AuNCs did not affect the nano-structural features of the CNF film and its basic structures, but could greatly increase the hydrophilicity, the flexibility and the thermal stability of CNF film, which might improve its application in antimicrobial wound-healing dressing. The prepared AuNCs@CNF films demonstrated high antibacterial properties toward Escherichia coli (E. coli) and Streptococcus mutans (S. mutans) both in vitro and in vivo, which can prohibit their growths and promote the healing of bacteria-infected wound, respectively. Thus, the prepared AuNCs@CNF film with great antibacterial properties could be applicable in biomedical field.

PurposeElectrospun scaffolds have been studied extensively for their potential use in bone tissue engineering. However, their hydrophobicity and relatively low matrix stiffness constrain their osteoinduction capacities. In the present study, we studied polymer electrospun scaffolds coated with hydrophilic hematite nanoparticles (αFeNPs) constructed using layer-by-layer (LbL) assembly to construct a bioactive interface between the scaffolds and cells, to improve the osteoinduction capacities of the scaffolds.Materials and methodsThe morphology of the αFeNPs was assessed. Surface properties of the scaffolds were tested by X-ray photoelectron spectroscopy (XPS), surface water contact angle, and in vitro protein adsorption test. The stiffness of the coating was tested using an atomic force microscope (AFM). In vitro cell assays were performed using rat adipose-derived stem cells (ADSCs).ResultsMorphology characterizations showed that αFeNPs assembled on the surface of the scaffold, where the nano assemblies improved hydrophilicity and increased surface roughness, with increased surface stiffness. Enhanced initial ADSC cell spread was found in the nano assembled groups. Significant enhancements in osteogenic differentiation, represented by enhanced alkaline phosphatase (ALP) activities, elevated expression of osteogenic marker genes, and increased mineral synthesis by the seeded ADSCs, were detected. The influencing factors were attributed to the better hydrophilicity, rougher surface topography, and harder interface stiffness. In addition, the presence of nanoparticles was believed to provide better cell adhesion sites.ConclusionThe results suggested that the construction of a bioactive interface by LbL assembly using αFeNPs on traditional scaffolds should be a promising method for bone tissue engineering.

Magnetic scaffolds incorporated with iron oxide nanoparticles (IONPs) are biocompatible and present excellent osteogenic properties. However, the underlying mechanism is unclear. In this study, 3D‐printed poly(lactic‐co‐glycolic acid) scaffolds were coated with IONPs using layer‐by‐layer assembly (Fe‐scaffold) to prepare magnetic scaffolds. The effects of this modification on osteogenesis were investigated by comparison with untreated scaffolds (Uncoated‐scaffold). The results showed that the proliferation of rat bone mesenchymal stem cells (rBMSCs) on the Fe‐scaffold was enhanced compared with those on the Uncoated‐scaffold (p < 0.05). The alkaline phosphatase activity and expression levels of osteogenic‐related genes of cells on the Fe‐scaffold were higher than those on the Uncoated‐scaffold (p < 0.05). Fe‐scaffold was found to promote the cell adhesion compared with Uncoated‐scaffold, including increasing the adhered cell number, promoting cell spreading and upregulating the expression levels of adhesion‐related genes integrin α1 and β1 and their downstream signaling molecules FAK and ERK1/2 (p < 0.05). Moreover, the amount of new bone formed in rat calvarial defects at 8 weeks decreased in the order: Fe‐scaffold > Uncoated‐scaffold > Blank‐control (samples whose defects were left empty) (p < 0.05). Therefore, 3D magnetic nanocomposite scaffolds enhanced the osteogenic capacities of rBMSCs in vitro and in a rat calvarial bone defect model by promoting cell adhesion. The mechanisms were attributed to the alteration in its hydrophilicity, surface roughness, and chemical composition.