Preface

Today, it is clear that we are surrounded by those materials that people commonly named as plastics and scientists prefer to designate as macromolecules or polymers. From early in the morning just after getting up we start using these materials, either natural or synthetic: a simple cotton towel to dry off after the shower, (a natural macromolecule); the comb or the toothbrush (mainly made from synthetic macromolecules); passing through the body or facial creams for maintaining the youth of our skin or used after shaving, all of these cosmetics containing polymers as ingredients; our clothing (shirt, pants, skirt, etc.) are manufactured using natural or synthetic macromolecules. Once we are ready, we should go to work in most cases not on foot (although shoes are made also with polymers) but by transport. This transportation will be mostly built by polymeric-based materials whether this is public (bus, train or subway) or private (car). The truth is that natural and synthetic macromolecules or polymers, plastics or elastomers, are an indispensable part of our daily lives and in many cases totally necessary. Once upon a time, we could think that all these enveloped systems would allow us to have a better quality of life, keeping us safe from possible attacks from outsiders. Who among us has not bought the “perfect” cleaner that kills all type of bacteria, and has painted his house with antifungal plastic paint, or has purchased a freezer, air conditioning or light switches that prevent bacterial proliferation? In fact, one of our colleagues has a footrest in the office that was sold as antimicrobial.

We are looking for systems that keep clean or fight against possible contamination and, in this way, people feel safer. This is always desirable but more especially in health and/or food areas since in these environments most of the tools and devices undergo sterilization procedures to avoid contamination. This objective has been pursued since antiquity and people have attempted to prevent from becoming infected, diseased or deceased. Today, this aim is more than a necessity, not only from the health-care standpoint, chasing the same goals as our ancestors but also to reach greater social and economic well-being.

When the RSC raised the idea for this book on polymeric materials with antimicrobial activity, at first, we had some doubts. It was clear that the subject was fascinating; we knew that because we have worked on antimicrobial polymeric materials, but what we did not know was whether we would be able to compose an excellent book, screening all the aspects that this field covers. We now have no doubt, we have been very fortunate to rely on well-known researchers in this wonderful and enigmatic field, offering to us not only their knowledge but also their generosity. Thus, this book is intended to serve both researchers working in the field of antimicrobial polymeric materials as well as those planning to enter into this area, but also for the many students of microbiology, chemistry, materials, physics, pharmacy, medicine, engineering, or others, who, not knowing what the future holds, think about the possibility to develop their scientific, technological, educational vocation on it or, simply, to acquire a background knowledge.

The book is divided into several chapters: Chapter 1, introduction to the antimicrobial polymeric materials, discusses the world of micro-organisms, how they are classified, quantified and really act. Understanding that, the reader will be submerged in the classification of antimicrobial polymers and the way to determine the activity of these systems. Chapter 2 describes the antimicrobial activity of chitosan and its derivatives focusing on their main applications in food and biomedical technologies but also in other areas, such as agriculture. The antimicrobial polymers with ammonium and phosphonium groups will be collected in Chapter 3. The different applications of these materials will also be presented, focusing more in their antimicrobial applications. Chapter 4 includes guanidine-based polymers, gemini surfactants and polymers, polymeric complexes formed with polymers and antibiotics and polymers containing antibiotics. These systems present the water-soluble antimicrobial polymers for functional cellulose fibres and hygiene paper products. The foreword on polymeric systems that mimic antimicrobial peptides will be presented in Chapter 5. On it, previous works dealing with mimic antimicrobial peptides are discussed, pointing out that there are some design rules for them and trends in their biological data. Antimicrobial textiles and clothing is detailed in Chapter 6, with a focus on the prevention of infection diseases in hospitals. The potential of different antimicrobial systems, including also halamine polymers, which are approved by the Environmental Protection Agency, are also commented. The synthesis and characterization by X-ray diffraction of polymeric and nonpolymeric metal complexes with special attention on silver ones are described in Chapter 7. The mode of action against microbes is discussed as a function of the used metal character to form the complexes. Chapter 8 is focused on polymer nanofibres with antimicrobial activities obtained by an electrospinning technique. As will be disclosed in this chapter the unique properties of the obtained fibres, with small diameters and large surface area to volume ratio, are of great interest in a variety of applications including filtration, tissue engineering scaffolds, drug-release systems, enzyme stabilization, protective clothes, sensors, carbonaceous materials, and controlled-drug delivery platforms. The preparation and the characteristics of polyurethanes are rationalized in Chapter 9, where we will see that these materials constitute a great fraction of biomedical devises. Thereof, the requirement to understand their antifouling and antimicrobial mechanisms of action has primary significance. One of the great concerns, especially in developed countries, is our dentition. In Chapter 10, the antimicrobial polymeric dental materials including all kinds of applied materials involved in the dental area, in particular those that release chlorhexidine antiseptic are discussed. Moreover, essential oils and natural compounds are used mainly in the food industry as antimicrobial and virucidal systems. Chapter 11 collects all the properties of such systems, with particular attention on those with virucidal potential since those are less explored. The carbon-based polymer systems, which are now powerfully emerging in different fields as exceptional candidates to shake up nanoscience and nanotechnology, are also revised in Chapter 12 as materials able to fight against micro-organisms. The use of copper and copper oxide in polymeric matrices is detailed in Chapter 13. The use of copper nanoparticles is nowadays remerging within the “nano” era. The toxicity of these particles is also discussed. The preparation of polymeric (nano)composites with zinc oxide and titanium dioxide, taking into consideration the photocatalytic activity of particles, is described in Chapter 14. The size and dispersion of particles into the matrix is widely discussed in it. The last chapter intends to expose antimicrobial systems different than those collected in the other chapters, e.g. those based on nitric oxide, combination and synergy of different approaches as innovative alternatives to fight against infections. Finally, we will comment on the expectations and trends of these antimicrobial materials.

Alexandra Muñoz-Bonilla, María L. Cerrada and

Marta Fernández-García

Instituto de Ciencia y Tecnología de Polímeros

(ICTP-CSIC), Madrid, Spain