Preface

This book, named Diatom Nanotechnology, presents the recent progress and current developments in this fascinating new field, which has emerged as a result of extensive interdisciplinary research on single-celled algae called diatoms. Diatoms, due to their unique silica nano/microstructures and properties, have attracted thousands of publications across many disciplines including marine biology, genetics, ecology, materials science, nanotechnology, engineering, optics, electronics, medicine and agriculture. This book presents the most recent ground-breaking discoveries and discussions of promising new avenues of research and development that reveal the enormous potential of emerging approaches in the field of diatom nanotechnology. This book is timely as the contributions are from the world’s leading experts, summarizing the present progress in this field with a focus on emerging applications. This book covers a selected range of topics presented throughout eleven chapters, which cover the most significant aspects of the applications of these outstanding bionanomaterials. I am particularly impressed with the judicious combination of chapters covering both fundamental and technical aspects of the various fields of diatom nanotechnology and their applications for the development of new technologies for addressing some of the world’s most concerning problems, such as energy, cancer, clean water and food production.

The first chapter, written by James Mitchel (Flinders University, Australia), gives an inspiring explanation as to why diatoms are ideal to study microscale and nanoscale manipulations from nature, because their structures can change the production of organic carbon and oxygen on a global scale, which makes them key for the biosphere. These principles can be translated across most of the biosphere, as well as in chemistry and engineering applications.

Chapter 2, written by Gary Rosengarten and co-authors (RMIT, Australia), deals with complex interactions between diatom structures and their fluidic environment on scales ranging from macroscale turbulence to nanoscale diffusion, explaining fundamental concepts regarding how diatoms can manipulate these in a range of ways that can affect their uptake of nutrients and sorting of particles. These include changes in buoyancy, rotation and, on the nanoscale, local manipulation of streamlines over their surface, rotation, and filtration through the silica pores, suggesting how these concepts developed by diatoms could be translated and engineered into new materials and devices.

Chapter 3, by Vandana Vinayak and co-authors (India), highlights the most exciting emerging research and developments in the nanoengineering of diatom surfaces for nanodevices and nanosensors, as well as their biomedical applications, including a “lab on a chip” for detecting antibodies and biomolecules, and biosensing devices for disease diagnostics.

Chapter 4, by G. L. Rorrer (Oregon University, USA), highlights biological and chemical approaches to functionalize nanostructured diatom frustules as an amazing new platform for bottom-up assembly and functionalization for optoelectronic and bio-nanotechnology applications. Suggested future directions of this rapidly-evolving field include the development of planar diatom frustule biofabrication processes for thin-film devices, as well as the genetic engineering of diatom cells to express functional biomolecules anchored to the frustule biosilica for broad bio-nanotechnology applications.

Chapter 5, written by Luca de Stefano and co-authors (Italy), reviews the recent results of studies by this group focused on the biophotonic properties of diatoms demonstrating how light manipulation by diatom micro/nanostructures, made by nature, can be effectively achieved by this low cost and largely available material and used for the development of low-cost optical biosensors, optical devices, micro-lenses etc.

Chapter 6, written by N. Kröger and co-authors (TU Dresden, Germany), summarizes the synthetic and biotechnological genetic routes for functionalizing diatom biosilica with proteins, and describes the properties and the first steps towards “real-world emerging applications” of these materials in catalysis, biosensing, and drug delivery.

Chapter 7, by Nicolas H. Voelcker and co-authors (Monash University, Australia), presents new and cutting-edge developments in the modification and application of diatom frustules as a natural platform for dye-sensitised solar cells and photo-electrochemical hydrogen production. This exciting advancement of green and lightweight energy harvesting, producing and storage devices could serve as a blueprint for future energy systems, suggesting that this research on diatom frustules for solar cells will hopefully begin to transition from the laboratory into working prototypes and onto the open market over the next decade.

Chapter 8, written by Yu Xin Zhang (Chongqing University, China), highlights the recent developments in the application of diatom structures combined with other nanomaterials for energy storage and production. Many exciting and promising concepts are presented using these diatom-based materials in energy-related fields, such as lithium ion batteries, supercapacitors, solar cells, hydrogen storage and thermal energy storage.

Chapter 9, by Hélder A. Santos and co-authors (University of Helsinki, Finland), presents recent progress in the use of diatoms for drug delivery applications developed by this group, showing the preparation of diatom carriers, surface bioengineering, biocompatibility tests, cellular uptake and capability to deliver different therapeutic molecules including anticancer drugs. The results and concepts presented are very encouraging toward the future use of diatom silica as a low-cost alternative to synthetic porous silica and other artificial materials for the preparation of future smart drug delivery devices.

Chapter 10, by D. Losic and co-authors (University of Adelaide, Australia), highlights the most outstanding advances in recent research on the use of diatom silica and silicon conversions for broad biomedical applications including tunable and responsive drug release, including in cancer therapy, theranostics, haemorrhage control and tissue engineering.

Finally, Chapter 10, written by D. Losic and Z. Korunic (University of Adelaide, Australia, and Diatom Research & Consulting, Canada) presents a review of recent progress in the application of diatom silica as a natural, non-toxic, chemical-free and resistance-free insecticide for stored grain protection, describing the impact of the origin, particle size, chemical composition, dosage, physical conditions and insect species on the insecticidal performance.

As a result of the highly interdisciplinary nature of this book, it should be of profound and immediate interest for a broad audience, including undergraduate students, educators, diatom enthusiasts, academics, industrial scientists and engineers across many disciplines, ranging from physics, to chemistry, engineering, materials science, marine biology, microscopy, bioengineering and medicine. This book gives an excellent overview for non-specialists by providing an up-to-date review of the existing literature in addition to providing new insights for interested scientists, giving a jump-start to this emerging research area. It can be used as a textbook for advanced courses in undergraduate schools or as a general teaching material for graduate students. Postdoctoral and senior researchers will find a stimulating description of state-of-the-art research in the field of bionanomaterials, biophotonics, nanofluidics and drug delivery. I hope this book will stimulate their interest and encourage them to start research in the exciting field of diatom nanotechnology and find new directions to solve many unsolved problems. I also believe that this book will be valuable to many entrepreneurial and business people, who are in the process of trying to better understand and evaluate nanotechnology and new nanomaterials for future high-tech emerging applications and disrupting industries.

On behalf of all authors, I am particularly pleased to recognize and acknowledge the efforts of the RSC publishing team in supporting the idea for publishing this book and providing enormous assistance during the preparation, reviewing and editing of the chapters.

Dusan Losic

The University of Adelaide, Australia