Droplet manipulation has found broad applications in various engineering and biomedical fields, such as biochemistry, microfluidic systems, drug delivery, and tissue engineering. Many methods have been developed to enhance the ability for manipulating droplets, among which magnetically actuated droplet manipulation has attracted widespread interests due to its remote, noninvasive manipulation ability and biocompatibility. This review summarizes the approaches and their principles that enable actuating the droplet magnetically. The potential biomedical applications of such a technique in bioassay, cell assembly, and tissue engineering are given.
Abstract4D bioprinting has emerged as a powerful technique where the fourth dimension “time” is incorporated with 3D bioprinting. In this technique, the printed bioconstructs are able to change their shapes or functionalities when triggered by either internal or external stimuli. In 4D bioprinting, the materials with/without cells enable the spatial–temporal control of the shape and/or functionality of the constructs. Using this method, researchers have printed bioconstructs that can transform into rather complex structures which are difficult to obtain directly by 3D bioprinting or other methods. Although the history of 4D bioprinting is short, rapid progress in this field is witnessed recently, with focus mainly on developing novel 4D printable materials, exploring novel methods to precisely control the process, and pursuing biomedical applications. To better understand this technique, the recent advances of 4D bioprinting, including the mechanism, structure design principles, applications in biomedical engineering, and also the facing challenges are reviewed.
Periodontitis
is an inflammatory disease worldwide that may result
in periodontal defect (especially alveolar bone defect) and even tooth
loss. Stem-cell-based approach combined with injectable hydrogels
has been proposed as a promising strategy in periodontal treatments.
Stem cells fate closely depends on their extracellular matrix (ECM)
characteristics. Hence, it is necessary to engineer an appropriate
injectable hydrogel to deliver stem cells into the defect while serving
as the ECM during healing. Therefore, stem cell-ECM interaction should
be studied for better stem cell transplantation. In this study, we
developed a bioprinting-based strategy to study stem cell–ECM
interaction and thus screen an appropriate ECM for in vivo repair
of alveolar bone defect. Periodontal ligament stem cells (PDLSCs)
were encapsulated in injectable, photocrosslinkable composite hydrogels
composed of gelatin methacrylate (GelMA) and poly(ethylene glycol)
dimethacrylate (PEGDA). PDLSC-laden GelMA/PEGDA hydrogels with varying
composition were efficiently fabricated via a 3D bioprinting platform
by controlling the volume ratio of GelMA-to-PEGDA. PDLSC behavior
and fate were found to be closely related to the engineered ECM composition.
The 4/1 GelMA/PEGDA composite hydrogel was selected since the best
performance in osteogenic differentiation in vitro. Finally, in vivo
study indicated a maximal and robust new bone formation in the defects
treated with the PDLSC-laden hydrogel with optimized composition as
compared to the hydrogel alone and the saline ones. The developed
approach would be useful for studying cell–ECM interaction
in 3D and paving the way for regeneration of functional tissue.
Organ-on-a-chip has emerged as a powerful platform with widespread applications in biomedical engineering, such as pathology studies and drug screening. However, the fabrication of organ-on-a-chip is still a challenging task due to its complexity. For an integrated organ-on-a-chip, it may contain four key elements, i.e., a microfluidic chip, live cells/microtissues that are cultured in this chip, components for stimulus loading to mature the microtissues, and sensors for results readout. Recently, bioprinting has been used for fabricating organ-on-a-chip as it enables the printing of multiple materials, including biocompatible materials and even live cells in a programmable manner with a high spatial resolution. Besides, all four elements for organ-on-a-chip could be printed in a single continuous procedure on one printer; in other words, the fabrication process is assembly free. In this paper, we discuss the recent advances of organ-on-a-chip fabrication by bioprinting. Light is shed on the printing strategies, materials, and biocompatibility. In addition, some specific bioprinted organs-on-chips are analyzed in detail. Because the bioprinted organ-on-a-chip is still in its early stage, significant efforts are still needed. Thus, the challenges presented together with possible solutions and future trends are also discussed.
The results suggested that LTC alleviated chilling injury in kiwifruit by improving antioxidant enzyme activities and maintaining higher levels of endogenous ABA, IAA and ZR, lower GA3 levels and higher ABA/GA3 and ABA/IAA ratios.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.