Oliver Schneider

IN VIVO AND IN VITRO EVALUATION OF FLEXIBLE, COTTONWOOL-LIKE NANOCOMPOSITES AS BONE SUBSTITUTE MATERIAL FOR COMPLEX DEFECTS

The easy clinical handling and applicability of biomaterials has become a focus of materials research due to rapidly increasing time and cost pressures in the public health sector. The present study assesses the in vitro and in vivo performance of a flexible, mouldable, cottonwool-like nanocomposite based on poly(lactide-co-glycolide) and amorphous tricalcium phosphate nanoparticles (PLGA/TCP 60:40). Immersion in simulated body fluid showed exceptional in vitro bioactivity for TCP-containing fibres (mass gain: 18%, 2 days, HAp deposition). Bone regeneration was quantitatively investigated by creating four circular non-critical-size calvarial defects in New Zealand White rabbits. The defects were filled with the easy applicable cottonwool-like PLGA/TCP fibres or PLGA alone. Porous bovine-derived mineral (Bio-Oss) was used as a positive control and cavities left empty served as a negative control. The area fraction of newly formed bone (4 weeks implantation) was significantly increased for TCP-containing fibres compared to pure PLGA (histological and micro-computed tomographic analysis). A spongiosa-like structure of the newly formed bone tissue was observed for PLGA/TCP nanocomposites, whereas Bio-Oss-treated defects afforded a solid cortical bone.

Micro-organism-Triggered Release of Silver Nanoparticles from Biodegradable Oxide Carriers Allows Preparation of Self-Sterilizing Polymer Surfaces

The antimicrobial activity of silver has attracted significant research interest and contributes to an exponentially growing use of this noble metal in commodity products. In this investigation, we describe a general approach to increase the antimicrobial activity of a silver-containing surface by two to three orders of magnitude. The use of 1-2-nm silver particles decorating the surface of 20-50-nm carrier particles consisting of a phosphate-based, biodegradable ceramic allows the triggered release of silver in the presence of a growing microorganism. This effect is based on the organisms requirements for mineral uptake during growth creating a flux of calcium, phosphate, and other ions to the organism. The growing micro-organism dissolves the carrier containing these nutrients and thereby releases the silver nanoparticles. Further, we demonstrate the rapid self-sterilization of polymer surfaces containing silver on calcium phosphate nanoparticles using a series of human pathogens. Colony-forming units (viable bacteria or fungi counts) have been routinely reduced below detection limit and suggest application of these self-sterilizing surfaces in hospital environments, food and pharmaceutical processing, and personal care.

Tissue engineered bone grafts based on biomimetic nanocomposite PLGA/amorphous calcium phosphate scaffold and human adipose-derived stem cells.

For tissue engineering of critical size bone grafts, nanocomposites are getting more and more attractive due to their controllable physical and biological properties. We report in vitro and in vivo behaviour of an electrospun nanocomposite based on poly-lactic-co-glycolic acid and amorphous calcium phosphate nanoparticles (PLGA/a-CaP) seeded with human adipose-derived stem cells (ASC) compared to PLGA. Major findings were that cell attachment, three-dimensional ingrowth and proliferation were very good on both materials. Cell morphology changed from a spindle-shaped fibroblast-like form to a more roundish type when ASC were seeded on PLGA, while they retained their morphology on PLGA/a-CaP. Moreover, we found ASC differentiation to a phenotype committed towards osteogenesis when a-CaP nanoparticles were suspended in normal culture medium without any osteogenic supplements, which renders a-CaP nanoparticles an interesting osteoinductive component for the synthesis of other nanocomposites than PLGA/a-CaP. Finally, electrospun PLGA/a-CaP scaffold architecture is suitable for a rapid and homogenous vascularisation confirmed by a complete penetration by avian vessels from the chick chorioallantoic membrane (CAM) within one week.

Flexible, silver containing nanocomposites for the repair of bone defects: antimicrobial effect against E. coli infection and comparison to tetracycline containing scaffolds

Bone regeneration in infected tissue or areas with high bacteria concentrations such as the oral cavity requires combining disinfection with biomaterial properties. Classical antibiotics typically provide excellent short term protection against re-infection of a defect but are typically washed out of an operation site within days. The present work investigates the use of silver on amorphous tricalcium phosphate (TCP) nanoparticles for electrospun, highly porous poly(lactide-co-glyclolide) (PLGA) fibrous composites. In vitro bioactivity tests of the wool-like composite PLGA/Ag-TCP (80 : 20) containing 0.5 wt% silver showed rapid hydroxyapatite deposition on the nanocomposite within 2 days. Antibacterial tests using E. coli demonstrated a strongly prolonged antibacterial effect of the scaffolds containing finely dispersed silver on TCP if compared to current clinically used methods based on soaking the scaffolds with a tetracycline solution prior to implantation.

Light-curable polymer/calcium phosphate nanocomposite glue for bone defect treatment

Light-curable, methacrylate-based resins are clinically used for complex defect repair in dentistry (Heliobond). The present study investigates how such easy-to-apply polymers may be used on a much broader range of applications, particularly for gluing wet bone. We investigate the significantly improved adhesion of the polymer to wet bone surfaces in a close to in vivo setup using freshly cut cow hip bone as a model. The use of a reactive filler (20 wt.% amorphous, glassy calcium phosphate nanoparticles, a-CaP) allows for combination of the properties of the polymer (strength; light-curing) and the reactive filler (recrystallization of amorphous CaP to hydroxyapatite within minutes). This filler alone has been earlier suggested for use as an injectable bone cement since it reacts under in vivo conditions within 10-15 min. Our study transfers this reactivity into a composite, thus using the reactive CaP phase to establish an improved adhesion of the composite to wet bone surfaces. Additional in vitro bioactivity tests, compressive and tensile strength suggest use of such light-curable nanocomposites for complex-shaped load-bearing implant materials and fracture repair.

Improving Service Operation Performance by a Cross-Industry Reference Model

The importance of business related services has been growing consequently during the past years. Industrial Services constitute the greatest share of business related service with 30% of their intermediate output. But those kinds of services are facing tremendous challenges in terms of synchronizing their process with the manufacturing processes of their customers. The EU funded project InCoCo-S aims to tackle these challenges by the development of an innovative reference model for the collaboration between Service Providers and Manufacturers. Currently, the development of the structure of the reference model is finished and its validation has already begun. In this scope, SKF, as one of the consortium partners, is currently implementing the results in their new service division — Windmill Condition Monitoring. This paper provides detailed information about conducted surveys within the InCoCo-S project, the Reference Model and its practical application.

The Concept of Modularisation of Industrial Services

The paper summarises findings from an action research project on modularisation of industrial services. Based on literature about modularisation of physical goods and literature on modularisation of services, several research gaps are highlighted and appropriate approaches discussed. Module drivers ad- dressing modularisation benefits are transferred to services. Interdependencies among service elements are presented. Research gaps on design opportunities of modular service products are addressed and possible analogies from modulari- sation of physical goods are introduced.

The Value of Lead Logistics Services

Logistics Services are one of the most outsourced functions within a supply chain. This is due to easily transferrable know-how and traceable direct cost reductions, which directly impact the profit and loss statement. However, an effective management of materials and transportations on the supply and deliver side also carries indirect benefits by positively influencing the cash flow and the amount of capital locked up in inventories. Therefore, it also affects the balance sheet and the company’s profitability. This paper describes an approach to make these effects transparent and traceable, by linking operational performance to the resulting changes in working capital. Having transparency on the direct and indirect effects fosters the service relationship and allows for new pricing concepts which carry advantages for both service provider and customer. The approach was developed in a collaborative action research project with a world leading provider of lead logistics services.

Understanding the Interdependences Among Performance Indicators in the Domain of Industrial Services

Within the context of the EU-Project InCoCo-’s’, one of the key aims is to standardize integrative industrial service processes in order to facilitate transparency on service operation performance and the resulting customer benefit. Therefore the Service Performance Measurement System (SPMS) has been developed in order to quantify both the efficiency and effectiveness of industrial service operation activities and to support the measurement of customers’ benefit through industrial service activities. But performance indicators are only a measurable expression of the underlying system performance, a system which is ordinarily complex in nature. It follows, therefore, that it would be beneficial to understand the interdependences between performance indicators in order to better utilize them in evaluating the options for improvements in system performance and the monitoring of an often complex system. Based on a comprehensive literature review and making best use of the tools and expertise available to the InCoCo-S consortium, a process to develop an understanding of the interdependences between performance indicators was created and executed. The results provide both the service provider and the manufacturing customer with an insight into those performance indicators to be targeted for improvement actions and those better suited to monitoring.

Entwicklung eines Leistungsmesssystems für industrielle Dienstleistungen

Kurzfassung Der Wandel in der Bedeutung industrieller Dienstleistungen (DL), wie z.B. Reparatur und Modernisierung von Maschinen, Qualitätskontrollen oder Verpackung von Produkten, stellt die DL-Anbieter vor die Herausforderung, industrielle Serviceleistungen wirtschaftlich anzubieten und erfolgreich zu vermarkten (Service Sales). Dazu bedarf es an Instrumenten und Methoden, die den Anbieter dabei unterstützen, die Leistung seiner Dienstleistungsaktivitäten und den resultierenden (Mehr-)Wert, der sich durch die Inanspruchnahme für den Kunden (OEM) ergibt, transparent zu machen. Im Rahmen eines EU-Projekts wurde ein Leistungsmesssystem mit monetären und nicht-monetären Kennzahlen entwickelt, das den spezifischen Eigenschaften von Dienstleistungen gerecht wird und für sämtliche industrielle Services anwendbar ist.