Relative survivability of human osteoblasts is enhanced by 39 °C and ascorbic acid after exposure to photopolymerization ingredients

Photopolymerizable hydrogels offer great potential in cartilage tissue engineering due to their ability to conform to irregular defect shapes and be applied in a potentially minimally invasive manner. An important process requirement in the use of photopolymerizable hydrogels is the ability of the suspended cells to withstand low intensity ultraviolet light (UV) exposure (4–5 mW/cm²) and photoinitiator concentrations. For cartilage integration with underlying subchondral bone tissue, robust localized osteoblast activity is necessary. Yet, while it is known that osteoblasts do not respond well to UV light, limited work has been conducted to improve their survivability. In this study, we evaluated the cellular cytotoxicity of five different human cell sources at different UV exposure times, with and without a commercially used photoinitiator. We were able to confirm that human osteoblasts were the least tolerant to varying UV exposure times in comparison to bone marrow stem cell, periodontal ligament cell, smooth muscle and endothelial cell lineages. Moreover osteoblasts cultured at 39 °C did not deteriorate in terms of alkaline phosphatase expression or calcium deposition within the extracellular matrix (ECM), but did reduce cell proliferation. We believe however that the lower proliferation diminished osteoblast sensitivity to UV and the photoinitiator. In fact, the relative survivability of osteoblasts was found to be augmented by the combination of a biochemical factor and an elevated incubation temperature; specifically, the use of 50 mg/l of the anti-oxidant, ascorbic acid significantly (P < 0.05) increased the survivability of osteoblasts when cultured at 39 °C. We conclude that ascorbic acid at an incubation temperature of 39 °C can be included in in vitro protocols used to assess cartilage integration with bone ECM. Such inclusion will enhance conditions of the engineered tissue model system in recapitulating in vivo osteoblast activity.     

Effect of aeration rate on the anti-biofouling properties of cellulose acetate nanocomposite membranes in a membrane bioreactor system for the treatment of pharmaceutical wastewater

Abstract

The adhesiveness and stability of ubiquitously distributed biofilms is a significant issue in many areas such as ecology, biotechnology and medicine. The magnetic particle induction (MagPI) system allows precise determinations of biofilm adhesiveness at high temporal and spatial resolution on the mesoscale. This paper concerns several technical aspects to further improve the performance of this powerful experimental approach and enhance the range of MagPI applications. First, several electromagnets were built to demonstrate the influence of material and geometry with special regard to core remanence and magnetic strength. Secondly, the driving force to lift up the particles was evaluated and it was shown that both the magnetic field strength and the magnetic field gradient are decisive in the physics of the MagPI approach. The intricate combination of these two quantities was demonstrated with separate experiments that add permanent magnets to the MagPI system.     

Modulation of hydrogel networks by metal ions

Self-assembling hydrogels are receiving great attention for both biomedical and technological applications. Self-assembly of protein/peptides as well as organic molecules is commonly induced in response to external triggers such as changes of temperature, concentration, or pH. An interesting strategy to modulate the morphology and mechanical properties of the gels implies the use of metal ions, where coordination bonds regulate the dynamic cross-linking in the construction of hydrogels, and coordination geometries, catalytic, and redox properties of metal ions play crucial roles. This review aims to discuss recent insights into the supramolecular assembly of hydrogels involving metal ions, with a focus on self-assembling peptides, as well as applications of metallogels in biomedical fields including tissue engineering, sensing, wound healing, and drug delivery.     

Development and in vitro evaluation of chitosan-Eudragit RS 30D composite wound dressings

The purpose of this research was to design and evaluate chitosan-based films intended for wound dressing application. Required properties for successful wound dressing, such as liquid uptake, vapor and oxygen penetration, bioadhesiveness, and film elasticity, were examined. Water uptake and vapor penetration of the films were determined gravimetrically, while oxygen penetration was determined by Winkler’s method. The bioadhesive properties were determined with an in-house pulley system instrument using a pig gut model. Film elasticity was determined with a stretch test using an Instron apparatus. The results showed that pure chitosan films exhibited relatively high liquid uptake and the adsorption tended to decrease with the addition of Eudragit RS 30D. Moisture vapor and oxygen were found to be able to penetrate through all film formulations in comparable amounts. The bioadhesiveness test tended to show lower bioadhesive properties with the addition of Eudragit RS 30D. The formulation containing only chitosan exhibited low elongation of the film at 2 N, but the film elasticity increased with the addition of Eudragit RS 30D. In conclusion, the addition of Eudragit RS 30D could improve a film’s mechanical properties but lower its bioadhesiveness. Published: March 24, 2006     

Release studies from smart hydrogels as carriers for piroxicam and copper(II)-oxicam complexes as anti-inflammatory and anti-cancer drugs. X-ray structures of new copper(II)-piroxicam and -isoxicam complex molecules

Piroxicam H₂PIR (H₂PIR, 4-hydroxy-2-methyl-N-pyridin-2-yl-2H-1,2-benzothiazine-3-carboxamide 1,1-dioxide), [Cu(HPIR)₂(H₂O)₂] previously prepared and tested from this laboratory and at National Institute of Health, National Cancer Institute, Developmental Therapeutic Program, NIH-NCI-DTP, USA [R. Cini, G. Tamasi, S. Defazio, M.B. Hursthouse, J. Inorg. Biochem. 101 (2007) 1140-1152, and references cited therein], [Cu(HMEL)₂(DMF)] (H₂MEL, 4-hydroxy-2-methyl-N-(5-methyl-1,3-thiazol-2-yl)-2H-1,2-benzothiazine-3-carboxamide 1,1-dioxide; DMF, N,N-dimethylformamide), [Cu(HISO)₂] (H₂ISO, 4-hydroxy-2-methyl-N-(5-methylisoxazol-3-yl)-2H-1,2-benzothiazine-3-carboxamide 1,1-dioxide), and [Cu(HTEN)₂(H₂O)₂] (H₂TEN, 4-hydroxy-2-methyl-N-pyridin-2-yl-2H-thieno[2,3-e][1,2]thiazine-3-carboxamide 1,1-dioxide), were loaded on CMH2 hydrogel (co-1:10-poly(N-methacryloyl-l-histidine-co-N-isopropylacrylamide) cross-linked with N,N′-ethylene-bis-acrylamide (EBA) 2%) and the kinetics of release of Cu-HPIR species in several media were studied. The release of Cu(HPIR)₂ in DMSO from CMH2 hydrogel after swelling and loading from DMSO followed a diffusion controlled process. The release of Cu(HPIR)/Cu(HPIR)₂ from dried CMH2 hydrogel after swelling and loading from THF solution, then soaking into water/DMSO 95:5 v/v (pH 5.6) followed a relaxation controlled and diffusion controlled mechanism. The amount of Cu(HPIR)₂ released in the medium reached 0.03 μg Cu/mg gel/mL, i.e. ca 0.8 μM within 48 h that compares well with the IC₅₀ values reported for metal based drugs like carboplatin (diammino(1,1-cyclobutandicarboxylato)platinum(II)) against certain human tumor cell lines. The release studies performed by monitoring both the absorbance values at 362 nm (sensitive to metal-bound HPIR⁻) and the content of Cu via AAS, showed an excellent agreement with the Cu(HPIR)₂ or Cu(HPIR)₂ stoichiometry, depending on the delivery medium. Corresponding studies were performed for other Cu(oxicam-H)₂ species in different delivery media.     

Strong green fluorescent hydrogels with Ba2MgSi2O7:Eu2+ phosphor embedded in cellulose

Non‐cytotoxic and green‐emitting fluorescent hydrogels were constructed from a cellulose solution containing Ba₂MgSi₂O₇:Eu²⁺ green phosphor in a NaOH/urea aqueous system. The structure, optical properties and cytotoxicity of these hydrogels were studied. The Ba₂MgSi₂O₇:Eu²⁺ phosphor particles were dispersed evenly in the cellulose hydrogel matrix. Good luminescent properties of Ba₂MgSi₂O₇:Eu²⁺ phosphor were maintained in the hydrogels, leading to strong green emission under ultraviolet excitation. Fluorescent hydrogels have no obvious cytotoxicity in a 3‐(4,5‐dimethylthiazol‐2‐yl)‐2,5‐diphenyltetrazolium bromide (MTT) proliferation test, and have potential use in in vivo applications like optical imaging and drug delivery.     

Development of a simple coarse-grained DNA model for analysis of oligonucleotide complex formation

In this paper, we develop a coarse-grained nucleotide model for the purpose of simulating large-scale aptamer-based hydrogel network formation in future research. In the model, each nucleotide is represented by a single interaction site containing sugar, phosphate and base. Discontinuous molecular dynamics (DMD) simulations are performed to simulate formation and denaturation of oligonucleotide duplexes as a function of temperature. The simulated melting temperatures of oligonucleotide duplexes are calculated in simulations of systems with different sequences, lengths and concentrations of oligonucleotides, and compared to data from the OligoAnalyzer tool. The denaturation of oligonucleotide triplexes containing a hybridised structure of three different oligonucleotides is analysed using both simulations and experiments. The nucleotide model is found to be a good predictor of the oligonucleotide’s hybridised state for both duplexes and triplexes. This coarse-grained model has wide ranging applications in the development or optimisation of DNA-based technologies including DNA origami, DNA-enabled hydrogels and DNA-based biosensors.     

甘氨酸和赤藓糖醇胶饵对红火蚁工蚁的毒杀效果

前期研究发现甘氨酸和赤藓糖醇对红火蚁Solenopsis invicta Buren有较好的毒杀效果,为进一步挖掘这两种物质的实际应用价值,在室内测试了甘氨酸和赤藓糖醇不同浓度配比的水溶液及胶状饵剂对红火蚁工蚁的毒杀效果.结果显示,20％的配比为1∶3、3∶1的赤藓糖醇和甘氨酸溶液喂饲48 h红火蚁工蚁的死亡率分别为8...     

Progress of new label-free techniques for biosensors: a review

The detection techniques used in biosensors can be broadly classified into label-based and label-free. Label-based detection relies on the specific properties of labels for detecting a particular target. In contrast, label-free detection is suitable for the target molecules that are not labeled or the screening of analytes which are not easy to tag. Also, more types of label-free biosensors have emerged with developments in biotechnology. The latest developed techniques in label-free biosensors, such as field-effect transistors-based biosensors including carbon nanotube field-effect transistor biosensors, graphene field-effect transistor biosensors and silicon nanowire field-effect transistor biosensors, magnetoelastic biosensors, optical-based biosensors, surface stress-based biosensors and other type of biosensors based on the nanotechnology are discussed. The sensing principles, configurations, sensing performance, applications, advantages and restriction of different label-free based biosensors are considered and discussed in this review. Most concepts included in this survey could certainly be applied to the development of this kind of biosensor in the future.