Biofactors - Volume 30, issue 4

Article Type: Other

Citation: BioFactors, vol. 30, no. 4, pp. 201-202, 2007

Authors: Han, Yuling Jamie | Loo, Say Chye Joachim | Lee, Joel | Ma, Jan

Article Type: Research Article

Abstract: The current review investigates the bioactivity of different glass interfaces created on thin glass cover slips as substrates. The interfaces studied are plain glass, functionalized glass using 0.5 M and 5 M of sodium hydroxide (NaOH) for 24 hrs, and glass coated with bioactive 58S Bioglass (58S). A biomimetic method, involving the exposure of the three interfaces to 1.5 times simulated body fluid (SBF) tests the bioactivity of the interfaces via creation of layer of Hydroxyapatite …(HA). Fluorinated SBF will precipitate fluorine doped HA (FHA) on a bioactive interface. Higher concentration of 1.5 times of SBF used in this study intended to accelerate the formation of HA and FHA layer over the substrate. HA and FHA is found to be precipitated on the thinly coated 58S. This paper, study also the thin film coatings of three forms of bioceramics – bioactive 58S, HA and FHA. The study, also proposes to draw a relation between the morphology of HA particles with duration of exposure to SBF, the effects of fluorine on the morphology and the cell interaction with bioactive 58S, HA and FHA interfaces using pre-differentiated osteoblastic MC3T3 cells. The analysis of cells in this study is confined to three parameters that include the attachment, proliferation and viability of cells. Tests employed for the analysis of the thin film coating of HA and FHA is restricted to qualitative X-Ray Diffraction and quantitative Field Emission Scanning Electron Microscope. Other mechanical tests such as shear test are not used to test the mechanical properties of this thin layer, due to the fact that the thin film is too thin for such analysis. Show more

Citation: BioFactors, vol. 30, no. 4, pp. 205-216, 2007

Authors: Sankar, Sriram | Rajalakshmi, T.

Article Type: Research Article

Abstract: Urinary catherization is a routine procedure in an intensive care unit (ICU) for monitoring the urine output of critically ill patients. The catheters which are most often used to help with urinary incontinence and retention also face problems like blockage, leakage and infection. These problems are due to proteins that adhere to the catheter surface and quickly build up on each other forming a protein layer. As the layers build up they can crystallize, providing the …major source of blockage and leakage. Current strategies to avoid these problems include coating a catheter with silver alloy to reduce bacteria on the catheter surface. However, silver alloy coatings can lead to increased silver resistance for bacteria. Since silver is already used as an antibacterial agent in many places in a hospital, it is even more possible that resistance can develop. An alternative solution is presented involving coating latex, a common urinary catheter material with a micro layer (5–100 microns) of polyethylene glycol. This hydrogel is applied using an interfacial photopolymerizatoin process with ethyl eosin as the photoinitiator. A 25 ppm concentration of ethyl eosin provided the strongest gel to surface adhesion and significantly lowered protein adhesion when compared to an uncoated latex substrate. Show more

Keywords: Hydrogel, polyethylene glycol, catheter, interfacial photo polymerization, latex, ethyl eosin

Citation: BioFactors, vol. 30, no. 4, pp. 217-225, 2007

Authors: Zhang, Hui | Gu, Chun-hu | Wu, Hong | Fan, Li | Li, Fei | Yang, Fan | Yang, Qian

Article Type: Research Article

Abstract: The aim of this study was to prepare konjac glucomannan (KGM)/chitosan (CS) film containing glycidyl methacrylate derivatized dextran (dex-GMA)/acrylic acid(AAc) nanoparticles loaded with antibacterial agent. In this study, An optimized procedure chosen from three methods was used to prepare Erythromycin (EM)-loaded poly(dex-GMA/AAc) nanoparticles and obtained nanoparticles ranged from 50–200 nm. Film was found to have equilibrium water content (EWC) 99.3% which could prevent exudates on wound bed from accumulating and also have …excellent water adsorption 2362.3 ± 55.2%; the water vapor transmission rate (WVTR) was 2335 ± 36 gm^{-2} day^{-1} and evaporative water loss from the film (EWL) was approximately 10% after 1 h and within 6 h it increased to 90%. Drug release of film containing nanoparticles or absent was determined, within 22 h accumulative release was 40.3%, 72.5% respectively. In conclusion, KGM/CS film containing nanoparticles could not only maintain a moist environment over wound bed in moderate to heavily exuding wound but also provide a continuous and sustained release of the antibacterial agent on the wound surface, which could be potential wound dressing. Show more

Keywords: Wound dressing, konjac glucomannan, chitosan, nanoparticles, erythromycin

Citation: BioFactors, vol. 30, no. 4, pp. 227-240, 2007

Authors: Drzazga, Z. | Michalik, K. | Maciejewska, K. | Trzeciak, H. | Kaszuba, M.

Article Type: Research Article

Abstract: Concentration of abundant elements e.g. calcium as well as of elements present in trace amount e.g. zinc in mandibles of 7, 14 an 28 day old newborn rats were determined by X-ray fluorescence analysis. The measurements were carried out by using a measurement system containing X-ray tube ECLIPSE-III and X-ray and gamma ray detector XR-100T-CdTe (Amptek Inc.). Concentration of calcium and zinc depended on the region of interest on the rat's mandible due to mineralization degree …conditioned by its function. Increasing age produced a remarkable increase in Ca content in contrast to Zn content in the bone tissue obtained from 7, 14 and 28 day old newborn rats. The calculated Zn/Ca concentration ratio was the biggest for 7 day old newborns and successively decreased with age indicating the important role of zinc at the beginning of bone ontogenesis. Show more

Keywords: Calcium, mandible, ontogenesis, X-ray fluorescence, zinc

Citation: BioFactors, vol. 30, no. 4, pp. 243-248, 2007

Authors: Xie, Fang | Goldys, Ewa | Baker, Mark

Article Type: Research Article

Abstract: We report here the first observation of appreciable enhancement of fluorescence induced by large Au colloids. Au monolayers with Au colloids of 40 nm, 59 nm, and 81 nm in radii, were formed on silane modified glass surfaces, respectively. The nanoparticle densities were varied by varying the deposition times and documented by scanning electron microscopy. Two types of samples were prepared, with large inter-particle distance and hence little or no inter-particle coupling and small inter-particle distance …with inter-particle coupling. The fluorescence enhancement was examined by using a self assembled monolayer of the fluorophore-protein conjugate with Deep Purple as a fluorophore and Bovine Serum Albumin as protein (DP-BSA). The data show the over 15 fold enhancement under optimized conditions and reveal strong variations with both inter-particle distance and particle size. Nanostructures of appropriate size with optimized inter-particle distance thus prepared can produce promising substrates for decent fluorescence enhancement. We demonstrated that the Au colloid monolayers on glass surfaces are promising substrates for fluorescence enhancement with outstanding macroscopic homogeneity. This important feature will pave the way for the application of our substrates in biotechnology and life sciences such as imaging and sensing of biomolecules in proteomics. Show more

Keywords: Nanoparticle, self assembly monolayer (SAM), MIFE substrate, deep purple-BSA conjugation

Citation: BioFactors, vol. 30, no. 4, pp. 249-253, 2007

Authors: Prince, Shanthi | Malarvizhi, S.

Article Type: Research Article

Abstract: The spectral reflectance measurements in tissue reveal physiological meaning. Normally, functional changes like, increase in total hemoglobin concentration, decrease in oxygen saturation, etc., are observed when there is an abnormality creeping in the normal tissue. These functional changes can act together to reveal disease by non-invasive near-infrared (NIR) spectroscopy, as it influence its optical properties. In the present study, a simple two dimensional, four layer model of breast is proposed. The four layers are …(i) skin (ii) adipose layer (iii) glandular tissue and (iv) muscle. Each layer is modeled with appropriate biological chromophores like hemoglobin, water, lipid and melanin. From the literature, the concentrations and molar extinction coefficients of the chromophores in various layers of the model are obtained. These values are used to calculate the wavelength dependent absorption characteristics of a particular layer. Monte Carlo simulation of diffuse reflectance (percentage of back reflected photons after multiple scattering with the broad variety of angles) are simulated for the modeled breast tissue with and without diseased condition. Near-infrared wavelengths are chosen, as the depth of penetration in tissue is more compared to UV and visible region. Simulations are carried out on the modeled breast tissue for different races (skin colors) at different NIR wavelengths. Results show significant changes in diffuse reflectance and relative absorbance for normal and diseased breast tissues for differently pigmented model. This model can be used to study the photo dynamical therapy, drug delivery and prognosis of cancer. Show more

Keywords: Diffuse reflectance, chromophores, modeling and Monte Carlo simulations

Citation: BioFactors, vol. 30, no. 4, pp. 255-263, 2007

Authors: Wang, Sigen | Liu, Zhijun | Sultana, Shabana | Schreiber, Eric | Zhou, Otto | Chang, Sha

Article Type: Research Article

Abstract: Micro-radiotherapy (micro-RT) system is specially designed for small animal (cancer cell) irradiation for basic and translational cancer research. We use carbon nanotube (CNT) field emission technology to develop a novel micro-RT system for image-guided high precision irradiation that is similar to the state of the art radiotherapy which our cancer patients receive today at mouse scale. Through the field emission control of its individually addressable x-ray pixel beams the micro-RT system electronically shapes the radiation field …and forms intensity modulation pattern. In this paper, we present the development of a carbon nanotube field emission cathode array chip – a key component for our novel micro-RT system. The prototype micro-RT CNT field emission cathode array chip has 5 × 5 individually addressable cathode pixels that are 1 mm in diameter and 2 mm in pitch. An individual CNT cathode pixel is predicted to generate a dose rate in the order of 100 cGy/min at the center of the irradiated mouse based on our Monte Carlo simulation. The temporal and spatial resolutions of the micro-RT system are expected to be ∼ ms level and < 2 mm respectively. Show more

Keywords: Cancer treatment, micro-radiotherapy (micro-RT) system, small animal model, carbon nanotubes, field emission

Citation: BioFactors, vol. 30, no. 4, pp. 265-270, 2007

Authors: Cai, Dong | Yu, Ying | Lan, Yucheng | Dufort, Fay J. | Xiong, Guangyong | Paudel, Trilochan | Ren, Zhifeng | Wagner, Dean J. | Chiles, Thomas C.

Article Type: Research Article

Abstract: Carbon nanotube and metal particle composites have been exploited to fabricate high performance electrochemical devices. However, the physical and chemical procedures to synthesize the composites are labor intensive and inefficient. Our study reveals an one-step wet chemistry method to accomplish fast and controllable production of gold nanoparticle (AuNP) and carbon naotube (CNT) composites. Such a process is sensitive to the surface charge. Especially, when functionalized with carboxyl groups, the CNTs carried negative …charges and showed low level association with negatively charged AuNPs. Thermal treatment was employed to decompose the carboxyl groups and render each CNT a charge-free surface thereby achieving a high level AuNP-CNT association. The fabricated glucose sensors demonstrated dependence of their sensitivities to the amount of AuNPs on the CNTs. The enhancement of sensitivity can be attributed to an accelerated electron transfer rate from glucose oxidase Gox to the electrode. The Michaelis-Menten kinetics also indicated improved performance in the glucose sensor made of AuNP-CNTs. Therefore, our research revealed a novel approach to produce metallic nanoparticle and CNT composite for fabricating high performance electrochemical sensors. Show more

Keywords: Carbon nanotube, sensor, nanoparticle, glucose oxidase

Citation: BioFactors, vol. 30, no. 4, pp. 271-277, 2007

Authors: Cho, Hyun-Young | Kong, Kwang-Hoon

Article Type: Research Article

Abstract: To gain further insight into herbicide detoxification, we studied the herbicide activity and specificity toward glutathione S-transferases from human and rice. In this study, the genes of the plant specific phi and tau class GST enzymes from Oryza sativa (OsGST) and human pi class GST enzyme (hGSTP1-1) were cloned and expressed in Escherichia coli with the pET and pKK vector systems, respectively. The gene products were purified to homogeneity by GSH Sepharose …affinity column chromatography. The herbicide specificity of the enzymes was investigated by enzyme-catalyzed conjugation of GSH with chloroacetanilide, diphenylether and chloro-s-triazine herbicides. The hGSTP1-1 showed very high specific activity toward atrazine. On the other hand, the phi class OsGST enzymes showed high specific activity toward chloroacetanilide herbicides, acetochlor, alachlor and metolachlor. The tau class GST enzymes displayed remarkable activity toward the diphenylether herbicide, fluorodifen. From these results, we conclude that the phi and the tau class GST enzymes show herbicide specificities and also they play an important role in the detoxification reaction of plant toward herbicides. Show more

Keywords: Glutathione S-transferase, herbicide detoxification, herbicide specificity, Oryza sativa GST, phi class GST, rice, tau class GST

Citation: BioFactors, vol. 30, no. 4, pp. 281-287, 2007