A porous scaffold for bone tissue engineering/45S5 Bioglass<Superscript>®</Superscript> derived porous scaffolds for co-culturing osteoblasts and endothelial cells

One of the major factors in the therapeutic success of bone tissue engineered scaffolds is the ability of the construct to vascularise post implantation. One of the approaches for improving vascularisation within scaffolds has been to co-culture human umbilical vein endothelial cells (HUVECS) with human osteoblasts (HOBS), which may then promote vascularisation and facilitate tissue regeneration. However, in order to mimic a natural physiological niche it is vital that the scaffold is able to support and promote the proliferation of both cell types and thus become a viable tissue engineered construct. In this study we report the development of a porous bioactive glass–ceramic construct and examine the interaction with human umbilical vein endothelial cells (HUVEC’s) and human osteoblast-like cell both in mono and co-culture. The study clearly demonstrated that the scaffolds were able to support both endothelial and human osteoblast cell proliferation both in mono and co-culture. A comparison of the proliferation response of HUVEC and HOB in mono-culture on the test scaffolds and the commercial porous hydroxyapatite was assessed over a 28 day period (4, 7, 14, 21 and 28 days), using alamar Blue^TM assay. Proliferation of HOB cells seeded in the scaffolds was consistently shown to be above those observed on commercial HA scaffolds.     

A Breakdown Voltage Multiplier for High Voltage Swing Drivers

A novel breakdown voltage (BV) multiplier is introduced that makes it possible to generate high output voltage swings using transistors with low breakdown voltages. The timing analysis of the stage is used to optimize its dynamic response. A 10 Gb/s optical modulator driver with a differential output voltage swing of 8V on a 50 Omega load was implemented in a SiGe BiCMOS process. It uses the BV-Doubler topology to achieve output swings twice the collector-emitter breakdown voltage without stressing any single transistor