Advances in antimicrobial photodynamic inactivation at the nanoscale

Nasim Kashef, Ying Ying Huang, Michael R. Hamblin

Research output: Contribution to journalReview articlepeer-review

153 Citations (Scopus)


The alarming worldwide increase in antibiotic resistance amongst microbial pathogens necessitates a search for new antimicrobial techniques, which will not be affected by, or indeed cause resistance themselves. Light-mediated photoinactivation is one such technique that takes advantage of the whole spectrum of light to destroy a broad spectrum of pathogens. Many of these photoinactivation techniques rely on the participation of a diverse range of nanoparticles and nanostructures that have dimensions very similar to the wavelength of light. Photodynamic inactivation relies on the photochemical production of singlet oxygen from photosensitizing dyes (type II pathway) that can benefit remarkably from formulation in nanoparticle-based drug delivery vehicles. Fullerenes are a closed-cage carbon allotrope nanoparticle with a high absorption coefficient and triplet yield. Their photochemistry is highly dependent on microenvironment, and can be type II in organic solvents and type I (hydroxyl radicals) in a biological milieu. Titanium dioxide nanoparticles act as a large band-gap semiconductor that can carry out photo-induced electron transfer under ultraviolet A light and can also produce reactive oxygen species that kill microbial cells. We discuss some recent studies in which quite remarkable potentiation of microbial killing (up to six logs) can be obtained by the addition of simple inorganic salts such as the non-toxic sodium/potassium iodide, bromide, nitrite, and even the toxic sodium azide. Interesting mechanistic insights were obtained to explain this increased killing.

Original languageEnglish
Pages (from-to)853-879
Number of pages27
Issue number5
Publication statusPublished - 28 Aug 2017
Externally publishedYes


  • Antimicrobial photodynamic inactivation
  • Drug-resistant microbial cells
  • drug delivery nanovehicles
  • efflux-pump inhibition
  • fullerenes
  • nanotechnology-based drug delivery
  • photochemical mechanisms
  • potentiation
  • titania photocatalysis
  • titanium dioxide photocatalysis

ASJC Scopus subject areas

  • Biotechnology
  • Electronic, Optical and Magnetic Materials
  • Atomic and Molecular Physics, and Optics
  • Electrical and Electronic Engineering


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