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Developing high-energy-density electrodes for lithium ion batteries (LIBs) is of primary importance to meet the challenges in electronics and automobile industries in the near future. Conversion reaction-based transition metal oxides are attractive candidates for LIB anodes because of their high theoretical capacities. This review summarizes recent advances on the development of nanostructured transition metal oxides for use in lithium ion battery anodes based on conversion reactions. The oxide materials covered in this review include oxides of iron, manganese, cobalt, copper, nickel, molybdenum, zinc, ruthenium, chromium, and tungsten, and mixed metal oxides. Various kinds of nanostructured materials including nanowires, nanosheets, hollow structures, porous structures, and oxide/carbon nanocomposites are discussed in terms of their LIB anode applications.

The stiffness of hydrogels has been reported to direct cell fate. Here, we found that the stiffness of hydrogels promotes the reprogramming of mouse embryonic fibroblasts into induced pluripotent stem cells (iPSCs). We prepared cell culture substrates of various stiffnesses (0.1, 1, 4, 10, and 20 kPa) using a polyacrylamide hydrogel. We found that culture on a soft hydrogel plays an important role in inducing cellular reprogramming into iPSCs via activation of mesenchymal-to-epithelial transition and enhancement of stemness marker expression. These results suggest that physical signals at the interface between cell and substrate can be used as a potent regulator to promote cell fate changes associated with reprogramming into iPSCs, which may lead to effective and reproducible iPSC-production.

Magnetic resonance imaging (MRI) is one of the most powerful molecular imaging techniques and can noninvasively visualize and quantify biological processes within the living organisms. The introduction of exogenous contrast agents has allowed specific visualization of biological targets as well as enhanced the sensitivity of MRI. Recently, paramagnetic inorganic nanoparticles showing positive T(1) contrast effect have been investigated as T(1) MRI contrast agents. Since the first trials of spherical nanoparticles of manganese oxide and gadolinium oxide, inorganic nanoparticles of various compositions and shapes have been used for in vivo and in vitro MRI because of their distinct signal enhancement in MR images. However, for clinical applications, important and complex issues such as safety and efficiency should be investigated by active research encompassing multiple disciplines, including chemistry, biology, biomedical engineering, and medicine.

We fabricated polystyrene substrates with lotus leaf surface structure (LLSS) and investigated cell behaviors, including attachment, morphology, proliferation, and differentiation of adipose-derived stem cells (ASCs) on them. Compared to the flat substrate, the LLSS substrate induced higher cell attachment rate, but did not significantly change the cell proliferation rate. In addition, ASCs on the LLSS substrate exhibited relatively narrower spreading morphology and less organized cytoskeleton, there by resulting in smaller sizes of cells than those on the flat substrate. According to histochemical staining and RT-PCR analysis, the LLSS substrate induced higher adipogenic differentiation of ASCs than the flat substrate, while chondrogenic and osteogenic differentiation were decreased.

The effects of RGD peptide conjugation to alginate hydrogel on the adipogenic differentiation of ASCs was investigated. After 3 d of culture, RGD-modified alginate hydrogels significantly stimulated FAK and integrin α1 gene expressions and vinculin expression in ASCs. In addition, RGD-modified alginate hydrogels significantly enhanced the adipogenic differentiation of human ASCs to exhibit higher expression levels of oil red O staining and adipogenic genes compared to those of the control group (unmodified gels). These results suggest potential applications of RGD-modified alginate gels for adipose tissue regeneration.

A MHDS has been employed to fabricate 3D scaffolds from PLGA with acetyl endgroups to achieve in vivo regeneration of cartilage tissue. The fabricated acetylated-PLGA scaffold showed open pores and interconnected structures. Rabbit chondrocytes were seeded on the PLGA scaffolds and transplanted immediately into subcutaneous sites of athymic mice. Chondrocytes transplantation with untreated PLGA scaffolds served as a control. Histological analysis of the implants at 4 weeks with H&E staining and alcian blue staining revealed higher extracellular matrix and GAG expression at the neocartilage in the PLGA-6Ac scaffolds than that of the PLGA-6OH scaffold group. This endgroup-modified scaffold may be useful for successful cartilage tissue engineering in orthopedic applications.

Transplanting stem cells differentiated towards a cardiac lineage can regenerate cardiac muscle tissues to treat myocardial infarction. In this study, we tested the hypothesis that transforming growth factor-b1 (TGF-b1) induces cardiomyogenic differentiation of adiposederived stromal cells (ADSCs) in vitro. Rat ADSCs were cultured with TGF-b1 (10ngml � 1 ) for 2 weeks in vitro. ADSCs cultured without TGF-b1 served as a control. The mRNA expression of cardiac-specific gene was induced by TGF-b1, while the control culture did not show cardiac-specific gene expression. Immunocytochemical analyses showed that a small fraction of ADSCs cultured with TGF-b1 for 2 weeks stained positively for cardiac myosin heavy chain (MHC) and a-sarcomeric actin. Flow cytometric analyses showed that the proportion of cells expressing cardiac MHC increased with TGF-b1. However, no mesenchymal differentiation (e.g., osteogenic and adipogenic differentiation) was detected other than cardiomyogenic differentiation. These results showed that TGF-b1 induce ADSC cardiomyogenic differentiation in vitro, which could be useful for myocardial infarction stem cell therapy. Copyright # 2009 John Wiley & Sons, Ltd. key words—adult stem cell; adipose-derived stromal cells; cardiomyogenic differentiation; transforming growth factor-b1; osteogenic differentiation

We have developed proteolytically degradable hydrogels with covalently immobilized fluorogenic protease substrates to visualize extracellular proteolytic activity and cell migration in three dimensions. Dye quenched-bovine serum albumin (DQ-BSA), a quenched, proteolytically activated fluorogenic substrate, was conjugated to poly(ethylene glycol) (PEG)-monoacrylate, and the product (DQ-BSA-PEG) was then covalently incorporated into proteolytically degradable and cell adhesive PEG hydrogels via photopolymerization. The DQ-BSA-PEG substrate in solution and incorporated into hydrogels exhibited significantly enhanced fluorescence after exposure to enzymes. Fibroblasts seeded within this hydrogel spread in three dimensions and extended lamellipodia. Cell migration and proteolytic activity were visualized using confocal microscopy. Proteolytic activity was concentrated near cell surfaces and remained present in the tracks where cell migration had occurred.

Poly(ethylene oxide/polylactide/poly(ethylene oxide) (PEO/PL/PEO) triblock copolymers, in which each block is connected by an ester bond, were synthesized by a coupling reaction between PL and PEO. Hydroxyl-terminated PLs with various molecular weights were synthesized and used as hard segments. Hydroxyl-terminated PEOs were converted to the corresponding acid halides via their acid group and used as a soft segment. Triblock copolymers were identified by Fourier transform infrared spectroscopy, 1H NMR, and gel permeation chromatography. Differential scanning calorimetry (DSC) and X-ray diffractometry of PEO/PL/PEO triblock copolymers suggested that PL and PEO blocks were phase-separated and that the crystallization behavior of the PL block was markedly affected by the presence of the PEO block. PEO/PL/PEO triblock copolymers with PEO 0.75k had two exothermic peaks (by DSC), and both peaks were related to the crystallization of PL. According to thermogravimetric analysis, PEO/PL/PEO triblock copolymer showed a higher thermal stability than PL or PEO. © 2002 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 40: 2545–2555, 2002

Three kinds of OH-terminated polylactides were synthesized by the ring-opening polymerization of lactide, with an alcohol such as dodecanol, glycerol, or pentaerythritol, in the presence of stannous octoate. Moreover, Cl-, NH2-, and COOH-terminated polylactides were synthesized from OH-terminated polylactides. The end groups of the polylactides were identified by 1H NMR and 13C NMR. According to thermal analysis, the cold crystallization temperatures of Cl-, NH2-, and COOH-terminated polylactides were higher than those of OH-terminated polylactides. The thermal stability of OH-terminated polylactides was poor, whereas NH2- and Cl-terminated polylactides were more resistant to thermal degradation. In a hydrolysis degradation test, the mass and molecular weight loss of COOH-terminated polylactides were high, whereas those of Cl- and NH2-terminated polylactides were much lower. These end-group effects were increased with an increasing number of chain arms. © 2001 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 39: 973–985, 2001

The stiffness of hydrogels has been reported to direct cell fate. Here, we found that the stiffness of hydrogels promotes the reprogramming of mouse embryonic fibroblasts into induced pluripotent stem cells (iPSCs). We prepared cell culture substrates of various stiffnesses (0.1, 1, 4, 10, and 20 kPa) using a polyacrylamide hydrogel. We found that culture on a soft hydrogel plays an important role in inducing cellular reprogramming into iPSCs via activation of mesenchymal-to-epithelial transition and enhancement of stemness marker expression. These results suggest that physical signals at the interface between cell and substrate can be used as a potent regulator to promote cell fate changes associated with reprogramming into iPSCs, which may lead to effective and reproducible iPSC-production.