Tissue engineering has become a promising strategy for repairing damaged cartilage and bone tissue. Among the scaffolds for tissue-engineering applications, injectable hydrogels have demonstrated great potential for use as three-dimensional cell culture scaffolds in cartilage and bone tissue engineering, owing to their high water content, similarity to the natural extracellular matrix (ECM), porous framework for cell transplantation and proliferation, minimal invasive properties, and ability to match irregular defects. In this review, we describe the selection of appropriate biomaterials and fabrication methods to prepare novel injectable hydrogels for cartilage and bone tissue engineering. In addition, the biology of cartilage and the bony ECM is also summarized. Finally, future perspectives for injectable hydrogels in cartilage and bone tissue engineering are discussed.
Gene transfer methods are promising in the field of gene therapy. Current methods for gene transfer include three major groups: viral, physical and chemical methods. This review mainly summarizes development of several types of chemical methods for gene transfer in vitro and in vivo by means of nano-carriers like; calcium phosphates, lipids, and cationic polymers including chitosan, polyethylenimine, polyamidoamine dendrimers, and poly(lactide-co-glycolide). This review also briefly introduces applications of these chemical methods for gene delivery.
Relationships between biodiversity and multiple ecosystem functions (that is, ecosystem multifunctionality) are context-dependent. Both plant and soil microbial diversity have been reported to regulate ecosystem multifunctionality, but how their relative importance varies along environmental gradients remains poorly understood. Here, we relate plant and microbial diversity to soil multifunctionality across 130 dryland sites along a 4,000 km aridity gradient in northern China. Our results show a strong positive association between plant species richness and soil multifunctionality in less arid regions, whereas microbial diversity, in particular of fungi, is positively associated with multifunctionality in more arid regions. This shift in the relationships between plant or microbial diversity and soil multifunctionality occur at an aridity level of ∼0.8, the boundary between semiarid and arid climates, which is predicted to advance geographically ∼28% by the end of the current century. Our study highlights that biodiversity loss of plants and soil microorganisms may have especially strong consequences under low and high aridity conditions, respectively, which calls for climate-specific biodiversity conservation strategies to mitigate the effects of aridification.
Although gold nanorods (GNRs) have been prepared with a wide range of methods for their uses as novel diagnostic and therapeutic agents, the synthesis of monodispersed GNRs with high yields and size tunability still requires further improvements. We report on a simple one-pot method for preparing highly monodispersed GNRs using phenols (e.g., hydroquinone, 1,2,3-trihydroxybenzene, and 1,2,4-trihydroxybenzene) as the reducing agent and NaBH 4 as the initiating reactant. Finetuning of the LSPR peak position of phenols-reduced GNRs from 550 to 1150 nm is accomplished by regulating the silver ion concentrations. The size of GNRs produced via phenols reduction can also be controlled by changing the NaBH 4 concentration. By systematically optimizing the concentrations of the reagents involved in the one-pot synthesis of GNRs, the yield (in many cases exceeding 90%) is significantly higher than that prepared with the commonly used reductant (e.g., ascorbic acid). The improved efficiency and controllability cut down the cost and time involved in GNRs production.
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