Preface

Quenched-phosphorescence oxygen sensing has now emerged as one of the most versatile, flexible and successful sensor technologies. This is largely because of the paramount significance of O₂ in life and biomedical sciences and the capabilities of this detection method to quantify oxygen concentration and other related parameters - directly, reversibly, non-invasively, accurately and in various gaseous, liquid and biological samples.

Since the pioneering proofs of concept studies of Dietrich Lubbers and David Wilson and their colleagues back in the late 70s and early 80s, this sensor technology has undergone major development and diversification. This work has produced a comprehensive panel of high-performance indicator dyes, sensing materials on their basis, advanced detection schemes, analytical methodologies and measurement instrumentation. Based on this technology and materials, a diverse range of applications has been developed and demonstrated in various settings. Over the three decade-long history of optical O₂ sensing, life science and biomedical applications have remained as its central pillar, while many other industrial and research applications have advanced as well.

On the other hand, only in the last 5–10 years, has O₂ sensing technology come to a stage, when it became widely accessible and affordable for ordinary users (researchers, clinicians, industry), and transferrable from high technology research and development labs into real-life environment, practical research and industrial applications. A number of commercial instruments and systems designed for routine laboratory use and also suitable for large-scale and large-volume applications such as biological screening, packaging, environmental and process control, quality assurance, have been introduced.

In many research labs, solid-state O₂ sensors have already become routine analytical tools used on a daily basis, like pH meters or UV-Vis spectroscopy. Further development of bioanalytical systems, which rely on quenched-phosphorescence oxygen sensing continues with great pace. At the same time, the level of awareness of both the research community and industry about such systems, their analytical and research capabilities and potential benefits of their adoption and use still remain low. These factors limit wider uptake and practical use of these technologies. More demonstrational and educational work needs to be conducted to break these barriers.

In this book we aimed to assemble a comprehensive collection of papers covering all core aspects of quenched-phosphorescence oxygen sensing technology and its applications. The first group of chapters describe the fundamentals and core aspects of O₂ sensing technique, the range of most common sensor dyes (Pt(ii)-porphyrins, Ru(ii)- and Ir(iii)-cyclometallated complexes), materials (solid-state sensors, soluble probes and nanoparticle formulations), fabrication technologies and dedicated instrumentation.

The second group of chapters describes specific life science applications and customized experimental setups and sensor systems (e.g. marine research and aquatic organisms, live cell analysis, oxygen imaging and oxygen transport in tissue, in vivo oxygen sensing and imaging) and application areas (cancer and stem cell research, photodynamic therapy, vascular biology and clinical applications, bio-imaging, microfluidic biochips, food packaging and safety). Some of these applications have already been commercialized or are close to this stage and therefore available for ordinary users.

The leading experts in respective areas, who have extensive hands-on experience with corresponding sensor systems and biological applications and know their merits and limitations, provided the chapters for the book. Altogether, this gives a comprehensive picture of the current status in this area, performance and capabilities of the different sensor systems and applications, and future avenues of research and development in this field.

The book is targeted at potential new users and young researchers who are not very familiar with these technologies and applications, but who can benefit from them. It is also of significant interest for established experts and researchers in O₂ sensing and current users of adjacent life science applications. Presenting them with the recent achievements in the broader area and related applications can further stimulate their work. We are hoping to attract many new researchers, young scientists and end-users to this very exciting technology.

Dmitri B. Papkovsky

Ruslan I. Dmitriev