ABSTRACT
The capacitance-voltage (C-V) and deep level transient spectroscopy (DLTS) measurements have been made on a Schottky Ti-ZnTe (p-type) diode containing CdTe self-assembled quantum dots (QD) and control diode without dots. The C-V curve of the QD diode exhibits a characteristic step associated with the QD states whereas the reference diode shows ordinary bulk behavior. A quasistatic model based on the self-consistent solution of the Poisson's equation is used to simulate the capacitance. By comparison of the calculated C-V curve with the experimental one, hole binding energy at the QD states is found to be equal about 0.12 eV. The results of DLTS measurements for the sample containing QDs reveal the presence of a low-temperature peak which is not observed for the control diode. Analysis of its behavior at different bias conditions leads to the conclusion that this peak may be related to the hole emission from the QD states to the ZnTe valence band. Its thermal activation energy obtained from related Arrhenius plot equals to 0.12 eV in accordance with the energy obtained from the Poisson's equation. Thus based on the C-V and DLTS studies it may be concluded that the thermal activation energy of holes from the QD states to the ZnTe valence band in the CdTe/ZnTe QD system is equal about 0.12 eV.
ABSTRACT
Oligo(polyethylene glycol) fumarate (OPF) hydrogel has been employed in musculoskeletal tissue engineering for photoencapsulation of chondrocytes and as a matrix for marrow stromal cells differentiation. In this study, we have studied the application of OPF hydrogel for coencapsulation of DNA and bone cells and examined whether coencapsulation can enhance gene transfer by maintaining the DNA within the cellular microenvironment. Our results showed that plasmid DNA encoding green fluorescence protein (GFP), coencapsulated with bone tumor cells, was capable of transfecting the cells, and the transfected tumor cells continuously expressed GFP protein over the time course of study (21 days). Furthermore, we have examined the coencapsulation of estrogen receptor (ER) encoding plasmid DNA and human fetal osteoblast cells (hFOB) that lack endogenous ER. Our results show that the transfected cells responded to estrogen as alkaline phosphatase (ALP), and estrogen response element (ERE)-directed luciferase enzyme activities increased with estrogen treatment. Taken together, these studies show that OPF hydrogel could be further explored for targeted gene delivery in bone and other tissues encapsulated within the hydrogels.
Subject(s)
DNA/metabolism , Estrogens/pharmacology , Gene Transfer Techniques , Hydrogel, Polyethylene Glycol Dimethacrylate/chemistry , Osteoblasts/drug effects , Alkaline Phosphatase/metabolism , Cell Line , Cell Survival/drug effects , Green Fluorescent Proteins/metabolism , Humans , Luciferases/metabolism , Osteoblasts/cytology , Osteoblasts/enzymology , Receptors, Estrogen/metabolism , Spectroscopy, Fourier Transform Infrared , TransfectionABSTRACT
Efficacious bone regeneration could revolutionize the clinical management of bone and musculoskeletal disorders. Although several bone morphogenetic proteins (BMPs) (mostly BMP-2 and BMP-7) have been shown to induce bone formation, it is unclear whether the currently used BMPs represent the most osteogenic ones. Until recently, comprehensive analysis of osteogenic activity of all BMPs has been hampered by the fact that recombinant proteins are either not biologically active or not available for all BMPs. In this study, we used recombinant adenoviruses expressing the 14 types of BMPs (AdBMPs), and demonstrated that, in addition to currently used BMP-2 and BMP-7, BMP-6 and BMP-9 effectively induced orthotopic ossification when either AdBMP-transduced osteoblast progenitors or the viral vectors were injected into the quadriceps of athymic mice. Radiographic and histological evaluation demonstrated that BMP-6 and BMP-9 induced the most robust and mature ossification at multiple time points. BMP-3, a negative regulator of bone formation, was shown to effectively inhibit orthotopic ossification induced by BMP-2, BMP-6, and BMP-7. However, BMP-3 exerted no inhibitory effect on BMP-9-induced bone formation, suggesting that BMP-9 may transduce osteogenic signaling differently. Our findings suggest that BMP-6 and BMP-9 may represent more effective osteogenic factors for bone regeneration.
Subject(s)
Adenoviridae/genetics , Bone Diseases/therapy , Bone Morphogenetic Proteins/genetics , Genetic Therapy/methods , Genetic Vectors/administration & dosage , Osteogenesis/genetics , Animals , Bone Morphogenetic Protein 2 , Bone Morphogenetic Protein 6 , Bone Morphogenetic Protein 7 , Cell Line , Genetic Vectors/genetics , Growth Differentiation Factor 2 , Injections, Intramuscular , Male , Mice , Mice, Nude , Reverse Transcriptase Polymerase Chain Reaction , Transforming Growth Factor beta/geneticsABSTRACT
PURPOSE: To evaluate the surface of the new PC IOLs commercially available in Poland in 2000. MATERIAL AND METHODS: Representative samples of new posterior chamber IOLs produced by 6 different companies (Alcon, Lensita, Medicontur, Opsia, Rayner, Storz), 5 of each, underwent surface examination with Novoscan 30 scanning electron microscope. RESULTS: Although, in general, smooth surface of optic and haptic parts were observed, three samples with irregularities were found. CONCLUSIONS: Comparing to previous evaluation performed in 1994, significant improvement in quality of IOLs surface was noted. No considerable differences in this field between above mentioned producers were observed.
Subject(s)
Lenses, Intraocular , Microscopy, Electron, Scanning , Biocompatible Materials , Humans , Surface PropertiesABSTRACT
PURPOSE: The aim of our study was to find the method of preparation of soft contact lenses for examination by SEM and next evaluation of deposits on the surfaces of frequent replacement lenses. MATERIAL AND METHODS: Frequent replacement contact lenses (Acuvue) stored in physiological saline, distilled water and sterile, dry container were prepared for examination by SEM (Novoscan 30). The best quality preparations were made from contact lenses stored in sterile, dry container and dried at room temperature. Acuvue contact lenses were taken from five young, healthy persons after one, two, three and four weeks of wearing. All the lenses were examined by SEM. RESULTS: We observed nearly all the components of tear film on the surfaces of the lenses. Flat, amorphic protein, crystalline deposits, fibrinous structures were usually observed. Sometimes the nectrotic cell were seen. In one preparation we found bacteria. The amount of deposits was not high and did not increase with four weeks time of lens usage. The quality and quantity of deposits were individually variable. CONCLUSIONS: The methods we choose let us to prepare good quality preparations of soft contact lenses for examination by SEM. On the surfaces of the frequent replacement contact lenses we found only a small quantity of deposits.
Subject(s)
Contact Lenses/microbiology , Microscopy, Electron , Humans , Microscopy, Electron/methods , Time FactorsABSTRACT
New posterior chamber lenses produced by 6 different companies, 3 from each, were examined in a Novoscan 30 scanning microscope. Practically in each lens irregularities of the surface of the haptic part were found and in many of them also in the optic part. The relatively smallest irregularities were observed in the lenses of the companies (in alphabetical order): Alcon, Domilens and Storz.
Subject(s)
Lenses, Intraocular/standards , Microscopy, Electron, ScanningABSTRACT
Results of examination of 6 transparent infant lenses in a scanning microscope are presented. Discussed is the structure of the termination of the zonula on the lens capsule and the appearance of lenticular fibres in the cortical and nuclear layers.
