Cu-MOF-Decorated 3D-Printed Scaffolds for Infection Control and Bone Regeneration

Abstract

Infection control and bone regeneration remain critical challenges in bone defect treatment. We developed a 3D-printed scaffold incorporating copper-based metal-organic framework-74 (Cu-MOF-74) within a polycaprolactone/hydroxyapatite composite. The synthesized Cu-MOF-74 exhibited a well-defined crystalline structure and rod-like morphology, as confirmed by TEM, EDS, FTIR, and XRD analyses. The scaffolds exhibited hierarchical pores (100-200 μm) and demonstrated tunable hydrophilicity, as evidenced by the water contact angles decreasing from 103.3 ± 2.02° (0% Cu-MOF-74) to 63.60 ± 1.93° (1% Cu-MOF-74). A biphasic Cu²⁺ release profile was observed from the scaffolds, reaching cumulative concentrations of 98.97 ± 3.10 ppm by day 28. Antimicrobial assays showed concentration-dependent efficacy, with 1% Cu-MOF-74 scaffolds achieving 90.07 ± 1.94% and 80.03 ± 2.17% inhibition against Staphylococcus aureus and Escherichia coli, respectively. Biocompatibility assessments using bone marrow-derived mesenchymal stem cells revealed enhanced cell proliferation at Cu-MOF-74 concentrations ≤ 0.2%, while concentrations ≥ 0.5% induced cytotoxicity. Osteogenic differentiation studies highlighted elevated alkaline phosphatase activity and mineralization in scaffolds with 0.05-0.2% Cu-MOF-74 scaffolds, particularly at 0.05% Cu-MOF-74 scaffolds, which exhibited the highest calcium deposition and upregulation of bone sialoprotein and osteopontin expression. These findings demonstrate the dual functional efficacy of Cu-MOF-74/PCL/HAp scaffolds in promoting both infection control and bone regeneration. These optimized Cu-MOF-74 concentrations (0.05-0.2%) effectively balance antimicrobial and osteogenic properties, presenting a promising strategy for bone defect repair in clinical applications.

Keywords: 3D printing scaffold; antibacterial properties; bone regeneration; copper; metal–organic frameworks; osteoinductive potential.

Figure 1

TEM image of Cu-MOF-74 (A) and the corresponding elemental mapping (B–F).

Figure 2

FTIR spectra (A) and XRD pattern (B) of Cu-MOF-74.

Figure 3

Photographs of the Cu-MOF-74/HAp/PCL composite scaffolds (A,B) and SEM images of the different Cu-MOF-74/HAp/PCL scaffolds: 0 Cu (C), 0.05 Cu (D), 0.1 Cu (E), 0.2 Cu (F), 0.5 Cu (G), and 1 Cu (H).

Figure 4

EDS mapping of the 0.2% Cu-MOF-74/HAp/PCL composite scaffolds: ch1 (A), Ca (B), O (C), C (D), P (E), and Cu (F).

Figure 5

Water absorption process of Cu-MOF-74/HAp/PCL (A) and released Cu²⁺ concentration of the Cu-MOF-74/HAp/PCL immersed in PBS solution (B).

Figure 6

Optical images (A) and graphs of the percentage inhibition of colony counts for Cu-MOF-74/HAp/PCL scaffolds against E. coli (B) and S. aureus (C) at different concentrations.

Figure 7

Images of BMSCs extracted from rat bone marrow (A). Cytoskeleton staining of BMSCs grown on different scaffolds for 3 d (B). Live/dead staining of BMSCs grown on different scaffolds for 3 d (C). The proliferation of BMSCs on different composite scaffolds for 1, 4, and 7 d (D). * p < 0.05, ** p < 0.01.

Figure 8

ALP staining (A) and ALP quantitative analysis (B) at 7 d and 14 d, and tetracycline staining (C) and Alizarin Red staining quantitative analysis (D) for 21 d; ** p < 0.01.

Figure 9

Western blot analysis of osteogenic marker expression (A–D) and quantitative analysis (D–F) at 21 days; (A,D) bone sialoprotein (BSP), (B,E) osteopontin (OPN), (C,F) osteocalcin (OCN); β-tubulin was used to normalize protein input and quantification; ** p < 0.01.