Abstract
To fight against antibiotic-resistant bacteria adhering and developing on medical devices, which is a growing problem worldwide, researchers are currently developing new "smart" materials and coatings. They consist in delivery of antimicrobial agents in an intelligent way, i.e., only when bacteria are present. This requires the use of new and sophisticated tools combining antimicrobial agents with lipids or polymers, synthetic and/or natural. In this review, three classes of innovative materials are described: hydrogels, nanomaterials, and thin films. Moreover, smart antibacterial materials can be classified into two groups depending on the origin of the stimulus used: those that respond to a nonbiological stimulus (light, temperature, electric and magnetic fields) and those that respond to a biological stimulus related to the presence of bacteria, such as changes in pH or bacterial enzyme secretion. The bacteria presence can induce a pH change that constitutes a first potential biological trigger allowing the system to become active. A second biological trigger signal consists in enzymes produced by bacteria themselves. A complete panel of recent studies will be given focusing on the design of such innovative smart materials that are sensitive to biological triggers.
Highlights
In recent years, there is an increase in antibiotic-resistant bacteria[1] and a decline in development of new antibiotics.[2]
21% and 28% of vancomycin was released from the Gel 2 and the Gel 3, respectively, at pH 7.4, while 78% and 93%, respectively, were released at pH 5. These results suggest that the increasing number of Schiff bases makes the hydrogel more pH-sensitive and is responsible for an increase in vancomycin release
NCs showed a significant activity of reduction of the cell viability (4.4 log), suggesting that the local concentration of octenidine dihydrochloride (OCT) due to release triggered by bacterial esterase is sufficient to inhibit S. mutans growth
Summary
There is an increase in antibiotic-resistant bacteria[1] and a decline in development of new antibiotics.[2]. Smart antibacterial systems, i.e. systems targeting bacterial infections and responsive to the bacterial microenvironment have been increasingly studied in recent years (Figure 1) Their ability to adjust the release of antibiotics according to the bacterial contamination allows for better efficacy of the antibacterial treatment by increasing the local drug concentration at the infected site. In alkaline media, where hydrogen bonds would be broken and electrostatic repulsions could repel chain segments, the hydrogel was expected to have higher swelling ratio and to favour the release of the drug These peptide-based bis-acrylate/AAc hydrogels loaded with triclosan as a drug were applied on bacteria and provided a fast drug release, achieving killing of the bacteria in a short period of time
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