In this work, chemiluminescent (CL) property of the carbon dots in the presence of peroxynitrous acid was studied. Peroxynitrous acid is formed by online mixing of nitrite and acidified hydrogen peroxide. The CL intensity was increased linearly with nitrite concentration in the range from 1.0 × 10(-7) M to 1.0 × 10(-5) M, and the detection limit was 5.3 × 10(-8) M (signal-to-noise ratio of S/N = 3). This method has been successfully applied to the determination of nitrites in pond water, river water, and pure milk, with recoveries in the range of 98%-108%. The CL mechanism of the peroxynitrous acid-carbon dots system was investigated using the CL, ultraviolet-visible light (UV-vis), and electron paramagnetic resonance (EPR) spectra. The electron-transfer annihilation of hole-injected and electron-injected carbon dots could mainly account for the CL emission, which sheds new light on the optical properties of the carbon dots.

Chondrocyte phenotype has been shown to dedifferentiate during passaged monolayer cultivation. Hence, we have investigated the expression profile of 27 chondrocyte-associated genes from both osteoarthritic cartilage tissue and healthy passaged human articular chondrocytes by quantitative real-time PCR. Our results indicate that the gene expression levels of matrix proteins and proteases in chondrocytes from monolayer culture decrease compared with those from cartilage tissue, while monolayer cultured chondrocytes from normal and osteoarthritic cartilage exhibit similar gene expression patterns. However, chondrocytic gene expression profiles were differentially altered at various stages of passage. The expression of the matrix proteins aggrecan, type II collagen, and fibromodulin inversely correlated with increasing passage number, while fibronectin and link protein exhibited a marked increase with passage. The expression of matrix proteinases MMP-3/9/13 and ADAMTS-4/5 decreased with passage, whereas proteinase inhibitors TIMP-2/3 were elevated. The cytokine IL-1 also showed increased expression with monolayer chondrocyte culture, while IGF-1 expression levels were diminished. No significant changes in TGF-b, or the chondrogenic transcription factors Sox-9, c-fos, or c-jun were observed. Our data indicates that cultured chondrocytes undergo dedifferentiation during monolayer culture, although the gene expression level of transcription factors necessary for chondrogenesis remains unchanged. This data may prove important for the future development of more specific and efficacious cultivation techniques for human articular chondrocyte-based therapies. ß

Identification of functional programmable mechanical stimulation (PMS) on tendon not only provides the insight of the tendon homeostasis under physical/pathological condition, but also guides a better engineering strategy for tendon regeneration. The aims of the study are to design a bioreactor system with PMS to mimic the in vivo loading conditions, and to define the impact of different cyclic tensile strain on tendon. Rabbit Achilles tendons were loaded in the bioreactor with/without cyclic tensile loading (0.25 Hz for 8 h/day, 0-9% for 6 days). Tendons without loading lost its structure integrity as evidenced by disorientated collagen fiber, increased type III collagen expression, and increased cell apoptosis. Tendons with 3% of cyclic tensile loading had moderate matrix deterioration and elevated expression levels of MMP-1, 3, and 12, whilst exceeded loading regime of 9% caused massive rupture of collagen bundle. However, 6% of cyclic tensile strain was able to maintain the structural integrity and cellular function. Our data indicated that an optimal PMS is required to maintain the tendon homeostasis and there is only a narrow range of tensile strain that can induce the anabolic action. The clinical impact of this study is that optimized eccentric training program is needed to achieve maximum beneficial effects on chronic tendinopathy management.

We report new chemiluminescent properties of fluorescent carbon dots in the presence of classical oxidants, such as acidic potassium permanganate and cerium(IV). The radiative recombination of oxidant-injected holes and electrons in the carbon dots accounts for the CL emission, which sheds new light on characteristics of the carbon dots.

In this paper, Mn-doped ZnS quantum dots (QDs) capped by a molecularly imprinted polymer (MIP) were synthesized. The results showed a high selectivity of the MIP-capped Mn-doped ZnS QDs toward the template molecule (4-nitrophenol) by QD fluorescence quenching. The application of MIP-capped Mn-doped ZnS QDs to the chemiluminescence (CL) system was also studied using a KIO(4)-H(2)O(2) system. This application combines the good selectivity of MIP with the high sensitivity of CL. The linear range of this CL system is from 0.1 to 40 microM, and the detection limit (DL) for 4-nitrophenol in the water can reach 76 nM. The method was also used in the real water samples, and the recoveries can fall in the range of 91-96%.

ATT may be a useful treatment of chronic Achilles tendinopathy.

No abstract

Chondrocyte is a unique cell type in articular cartilage tissue and is essential for cartilage formation and functionality. It arises from mesenchymal stem cells (MSCs) and is regulated by a series of cytokine and transcription factor interactions, including the transforming growth factor-beta super family, fibroblast growth factors, and insulin-like growth factor-1. To understand the biomechanisms of the chondrocyte differentiation process, various cellular model systems have been employed, such as primary chondrocyte culture, clonal normal cell lines (HCS-2/8, Ch-1, ATDC5, CFK-2, and RCJ3.1C5.18), and transformed clonal cell lines (T/C-28a2, T/C-28a4, C-28/I2, tsT/AC62, and HPV-16 E6/E7). Additionally, cell culture methods, including conventional monolayer culture, three-dimensional scaffold culture, bioreactor culture, pellet culture, and organ culture, have been established to create stable environments for the expansion, phenotypic maintenance, and subsequent biological study of chondrocytes for clinical application. Knowledge gained through these study systems has allowed for the use of chondrocytes in orthopedics for the treatment of cartilage injury and epiphyseal growth plate defects using tissue-engineering approaches. Furthermore, the potential of chondrocyte implantation for facial reconstruction, the treatment of long segmental tracheal defects, and urinary incontinence and vesicoureteral reflux are being investigated. This review summarizes the present study of chondrocyte biology and the potential uses of this cell in orthopedics and other disciplines.