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Infection with antibiotic-resistant bacteria is becoming a significant public health risk. In this study, we synthesized a series of imidazolium salt (IMS)-containing polymers and hydrogels and tested their antimicrobial properties against both gram-positive (Staphylococcus aureus and MRSA) and gram-negative (Escherichia coli and PA01) bacteria. IMSs were either grafted as side chains or functionalized in the main chain of linear polymers, which demonstrated antimicrobial properties with minimum inhibitory concentrations as low as 2 μg/mL. Similarly, the optimized IMS-containing hydrogel effectively killed MRSA with a 96.1% killing efficiency and inhibited the growth of PA01. These hydrogels also demonstrated high performance in terms of mechanical property (compressive strength >2 MPa) and were noncytotoxic toward human dermal fibroblasts. STATEMENT OF SIGNIFICANCE: A series of polyimidazolium hydrogels were fabricated with acrylamide monomer and poly(ethylene glycol) dimethacrylate by thermal-initiated polymerization. These hydrogels completely killed methicillin-resistant Staphylococcus aureus and inhibited the growth of Pseudomonas aeruginosa. More importantly, these hydrogels demonstrated adequate mechanical property and biocompatibility. These antimicrobial hydrogels have the potential as biomaterials for preventing infections associated with multidrug-resistant bacteria., (Copyright © 2019 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.)

Functional and perfusable vascular network formation is critical to ensure the long-term survival and functionality of engineered tissues after their transplantation. Although several vascularization strategies have been reviewed in past, the significance of microvessel organization in three-dimensional (3D) scaffolds has been largely ignored. Advances in high-resolution microscopy and image processing have revealed that the majority of tissues including cardiac, skeletal muscle, bone, and skin contain highly organized microvessels that orient themselves to align with tissue architecture for optimum molecular exchange and functional performance. Here, we review strategies to develop highly organized and mature vascular networks in engineered tissues, with a focus on electromechanical stimulation, surface topography, micro scaffolding, surface-patterning, microfluidics and 3D printing. This review will provide researchers with state of the art approaches to engineer vascularized functional tissues for diverse applications. STATEMENT OF SIGNIFICANCE: Vascularization is one of the critical challenges facing tissue engineering. Recent technological advances have enabled researchers to develop microvascular networks in engineered tissues. Although far from translational applications, current vascularization strategies have shown promising outcomes. This review emphasizes the most recent technological advances and future challenges for developing organized microvascular networks in vitro. The next critical step is to achieve highly perfusable, dense, mature and organized microvascular networks representative of native tissues., (Copyright © 2019 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.)

Proliferation and differentiation of bone-related cells are modulated by many factors such as scaffold design, growth factor, dynamic culture system, and physical simulation. Nanofibrous structure and moderate-intensity (1 mT-1 T) static magnetic field (SMF) have been identified as capable of stimulating proliferation and differentiation of osteoblasts. Herein, magnetic nanofibers were prepared by electrospinning mixture solutions of poly(L-lactide) (PLLA) and ferromagnetic Fe3O4 nanoparticles (NPs). The PLLA/Fe3O4 composite nanofibers demonstrated homogeneous dispersion of Fe3O4 NPs, and their magnetism depended on the contents of Fe3O4 NPs. SMF of 100 mT was applied in the culture of MC3T3-E1 osteoblasts on pure PLLA and PLLA/Fe3O4 composite nanofibers for the purpose of studying the effect of SMF on osteogenic differentiation of osteoblastic cells on magnetic nanofibrous scaffolds. On non-magnetic PLLA nanofibers, the application of external SMF could enhance the proliferation and osteogenic differentiation of MC3T3-E1 cells. In comparison with pure PLLA nanofibers, the incorporation of Fe3O4 NPs could also promote the proliferation and osteogenic differentiation of MC3T3-E1 cells in the absence or presence of external SMF. The marriage of magnetic nanofibers and external SMF was found most effective in accelerating every aspect of biological behaviors of MC3T3-E1 osteoblasts. The findings demonstrated that the magnetic feature of substrate and microenvironment were applicable ways in regulating osteogenesis in bone tissue engineering., (Copyright © 2015 Elsevier B.V. All rights reserved.)