Antimicrobial Coatings

Antimicrobial coatings include any chemical agent or active substance with the ability to kill or inhibit the growth of pathogens or disease-causing microorganisms. The materials used for this application typically exert antimicrobial effects via cellular membrane perturbation.

Materials:

 

  1. Graphene materials (GMs) – a group of antimicrobial materials that include fullerenes1, pristine graphene sheets, graphene oxides, graphite, and graphite oxides.2 Results showed that possible mechanisms for the antimicrobial activity might be due to bacterial membrane disruption upon physical contact and induction of oxidative stress caused by the generation of reactive oxygen species (ROS).3 Another known mechanism is the entrapment of microorganisms within aggregates of graphene sheets.4

 

  1. Graphene-like two-dimensional materials (2DMats) – the antibacterial activities of raw and chemically exfoliated MoS2 sheets were studied and the mechanism for the antimicrobial activities are similar to those of GMs.5

 

  1. Polycationic hydrogel – an antimicrobial hydrogel based on dimethyldecylammonium chitosan-graft-poly(ethylene glycol) methacrylate and poly(ethylene glycol) diacrylate, which was shown to have efficacy against Pseudomonas aeruginosa, Escherichia coli, Staphylococcus aureus and Fusarium solani. Proposed mechanism of the antimicrobial activity was by microbial membrane disruption caused by electrostatic interaction that allow sections of anionic microbial membrane to be distorted and drawn into the cationic internal nanopores of the hydrogel leading to microbial death.6

 

  1. Polymer brushes – are categorized into three main classifications: (a) polymer brushes comprising of bactericidal polymers, (b) functionalized polymer brushes wherein a bactericidal or bacteriostatic compound is either covalently linked or embedded in the brush film that can eventually diffuse, and (c) nonfouling polymer brushes that prevent bacterial adhesion and biofilm formation.7

 

  1. Silver nanoparticles – the bactericidal effect of silver nanoparticles8,9 were shown to be size-dependent, only within the 1-10 nm range, and the activity was attributed to several proposed mechanisms based on to the ability of ionic silver ions to cause the inactivation of the vital enzymes via the interaction with the thiol groups; hindering of the DNA replication process, and deformation of cellular membrane.

 

  1. Dendrimers – a multivalent lysine-based dendrimer VivaGel is currently undergoing clinical trials as a topically administered vaginal virucide to prevent HIV. Also, the unique property of dendrimers to traverse cellular membranes make this material suitable as a drug delivery system, g., dendrimer-doxorubicin conjugate.9

 References:

 

  1. Kostarelos, K., Novoselov, K. S. (2014) Graphene devices for life. Nature Nanotechnology 9:744-745.
  2. Liu, S., Zeng, T. H., Hofmann, M., Burcombe, E., Wei, J., Jiang, R., Kong, J., Chen, Y. (2011) Antibacterial activity of graphite, graphite oxide, graphene oxide, and reduced graphene oxide: membrane and oxidative stress. ACS Nano 5:6971-6980.
  3. Mao, H. Y., Laurent, S., Chen, W., Akhavan, O., Imani, M., Ashkarran, A. A., Mahmoudi, M. (2013) Graphene: promises, facts, opportunities, and challenges in nanomedicine. Chemical Reviews 113:3407-3424.
  4. Akhavan, O., Ghaderi, E., Esfandiar, A. (2011) Wrapping bacteria by graphene nanosheets for isolation from environment, reactivation by sonication, and inactivation by near-infrared irradiation. Journal of Physical Chemistry B 115:6279-6288.
  5. Yang, X., Li, J., Liang, T., Ma, C., Zhang, Y., Chen, H., Hanagata, N., Su, H., Xu, M. (2014) Antibacterial activity of two-dimensional MoS2 Nanoscale 6:10126-10133.
  6. Li, P., Poon, Y. F., Li, W., Zhu, H.-Y., Yeap, S. H., Cao, Y., Qi, X., Zhou, C., Lamrani, M., Beuerman, R. W., Kang, E.-T., Mu, Y., Li, C. M., Chang, M. W., Leong, S. S. J., Chan-Park, M. B. (2011) A polycationic antimicrobial and biocompatible hydrogel with microbe membrane suctioning ability. Nature Materials 10:149-156.
  7. Krishnamoorthy, M., Hakobyan, S., Ramstedt, M., Gautrot, J. E. (2014) Surface-initiated polymer brushes in the biomedical field: applications in membrane science, biosensing, cell culture, regenerative medicine, and antibacterial coatings. Chemical Reviews 114:10976-11026.
  8. Morones, J. R., Elechiquerra J. L., Camacho, A., Holt, K., Kouri J. B., Ramirez, J. T., Yacaman, M. J. (2005) The bactericidal effect of silver nanoparticles. Nanotechnology 16:2346-2353.
  9. Duncan, R., Gaspar, R. (2011) Nanomedicine(s) under the microscope. Molecular Pharmaceutics 8:2101-2141.