Antibacterial Hydrogels and Their Implications
Antimicrobial resistance (AMR) is the ability of microorganisms to resist the effects of a drug that were previously effectively treating the microbe [1-3]. Antibiotics have been extensively used in the antibacterial field and have significantly improved the quality of life for human beings by effectively suppressing various infections [4-6]. Antibiotic resistance happens when bacteria develop resistance against antibiotics, which thereby reduces or eliminates the effectiveness of antibacterial drugs. The bacteria survive and continue to multiply, causing more harm and making prevention and treatment a tedious task, hence making AMR a challenging global issue [7-10]. Antibiotics are well known for their crucial roles and applications. But their wrong use causes abuse and leads to major health concerns. The overuse and misuse of antibiotics and the reduced amount of novel antimicrobial drug development are a major cause of the aggravation of this crisis. Microbial resistance to multiple drugs is known as multidrug-resistant (MDR) whereas extensively drug-resistant (XDR) is often termed “superbugs” [11-14]. Conventional antibacterial treatments are ineffective, and infections persist due to antibiotic resistance. The instant emergence of antibiotic-resistant bacteria almost after the advanced antibiotics approval was challenging in cases of Fidaxomicin-resistant Enterococci (K-1476) and Methicillin- resistant Staphylococcus aureus (MRSA) . Pathogens like Pseudomonas aeruginosa, Staphylococcus aureus, and Escherichia coli pose severe health concerns. Wound healing delay, sepsis of the affected site, occurrence of pneumonia.
complications for ICU patients, transplant rejection, or even severe internal infections which are hard to detect and difficult to treat can be caused by AMR [16-20]. Global threats from AMR pathogenic microorganisms trigger the need for the advancement and development of novel antibacterial materials. In this context, recently several biomaterials and hydrogels have been synthesized, investigated, and characterized for their effective and efficient antibacterial activities. Hydrogels are smart materials which can represent antibacterial activities and can act as novel agents in the fight against AMR [21-24]. Hydrogel contains very high amounts of water and a specific structural complexity. Hydrogels are cross-linked polymer networks formed by either physical interactions or covalent bonds according to the change in diverse parameters such as pH, ionic strength, ultraviolet exposure, temperature, etc. [25— 27]. Hydrogel has broad applications in diverse fields such as wound healing/dress- ing, three-dimensional (3D) cell culture systems, tissue engineering, bioengineering, nanomedicine, and drug delivery [28-33]. Their better biocompatibility, higher adsorbent quality, and the feasibility to design and modify the hydrogels to mimic extracellular structures or specific parts of tissues makes them potential candidates for biomedical applications. Several nanomaterials based on metal ions and other bionanomaterials were discovered and investigated for their antibacterial activity [34-38]. In this chapter, we have reviewed the different types of antibacterial hydrogels and their implications, applications, and potential future scope.
Hydrogels as Antibacterial Agent and Their Implications
Hydrogels are natural or synthetic porous materials which consist of cross-linked polymers formed by either physical or chemical interaction [22, 23, 39]. Recently hydrogels have been comprehensively considered and implemented as an alternative material for antibacterial applications [29. 40-42]. There are mainly three classes of antibacterial hydrogels (Figure 9.1). These are inorganic nanoparticle-containing hydrogels (metal or metal oxide), antibacterial (antibiotics)-containing hydrogels, and inherent hydrogel (natural or synthetic) with antibacterial capabilities. The properties of hydrogels, such as hydrophilicity and porosity, have been utilized for
FIGURE 9.1 Schematic overview of various types of antimicrobial hydrogels.
the development of effective antibacterial candidates and drug delivery purposes. Antibacterial hydrogels could help resolve the challenges of antibiotic resistance. Antibacterial hydrogels could be used locally to avoid the side effects of systemic application. Antibacterial hydrogels, as a novel drug delivery system, offer sustainable release and prolonged antibacterial consequence. Additionally, synergestic application has advantages over aiming at a single target. However, multiple mechanisms involved with nanoparticles and other antibacterial constituents intricates the development of bacterial resistance. Thus, making hydrogels as a smart alternative to fight AMR varied component might exhibit synergistic effects which could provide broader antibacterial spectrum and effective antibacterial activity. High selectivity and negligible toxicity of these hydrogels would make them great impending candidates in the prevention and treatment of infections [43-45].