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UK Health Security Agency

NCTC and the science of small silverware

Biomedical research teams use microorganisms to understand the properties of microscopic particles. It is clear that scientists are using bacterial pathogens from the National Collection of Type Cultures (NCTC) to test a range of applications of nanoparticles in fighting infectious diseases. This was demonstrated after NCTC curators reviewed up to 100 studies published in 2018 to keep abreast of the value and uses of the collection in the wider scientific community.

Although it is believed that silver and copper nanoparticles were used by artisans to create a glittering glaze to their pottery in the Middle Ages, their use in pharmaceutical and medical applications has only progressed significantly over the past 50 years. Nobel-prize winning scientist Paul Ehrlich was credited with developing the theory that targeted delivery could greatly improve drug therapy at the turn of the twentieth century when the concept of nanoparticles and drug targeting was born1.

A research group in the UK are advancing Ehrlich’s theme more than 100 years later using NCTC 10662, a strain of Pseudomonas aeruginosa, to assess the efficacy of an inhalation formulation of hybrid silver/ciprofloxacin nanoparticles. P. aeruginosa causes recurrent pulmonary infections in people with cystic fibrosis and although ciprofloxacin is still an effective treatment against this bacterium, it is challenging to deliver the drug to the highly viscous environment found in the lungs of patients with this disease. It is well-known that silver has antimicrobial and mucolytic properties and this research demonstrated that these hybrid nanoparticles are effective against P. aeuginosa embedded in a biofilm2.

By comparison, a collaboration of scientists from Australia and China developed the first generation of self-sterilising dissolving microneedle transdermal patches containing silver nanoparticles.  Microneedle arrays consist of miniaturised (<1 mm length) needle-shaped structures that have gained interest for the delivery of vaccines and can also be incorporated into medicated adhesive patches placed on the skin to deliver drugs through the skin into the bloodstream.  This group included the use of NCTC 6749, a strain of P. aeruginosa that was given to the collection in 1944, as part of their testing protocol3.   

Meanwhile, scientists in Iran turned their attention to a greener approach for synthesising silver nanoparticles for medical applications, recognising a growing need to develop eco-friendly processes that reduce the use of environmentally toxic chemicals. They successfully accomplished the biosynthesis of silver nanoparticles using an extract of Prosopis farcta fruit as a reducing agent, evaluating the antibacterial activity of the both the fruit extract and the silver nanoparticles with a range of bacteria including NCTC 7465, a strain of Streptococcus pneumoniae4.

References:

  1. Kreuter, J. (2007). "Nanoparticles—a historical perspective." International journal of pharmaceutics 331(1): 1-10. doi:10.1016/j.ijpharm.2006.10.021
  2. Al-Obaidi, H., et al. (2018). "Fabrication of inhaled hybrid silver/ciprofloxacin nanoparticles with synergetic effect against Pseudomonas aeruginosa." European Journal of Pharmaceutics and Biopharmaceutics128: 27-35. doi.org/10.1016/j.ejpb.2018.04.006 
  3. González García, L. E., et al. (2019). "Self-sterilizing antibacterial silver-loaded microneedles." Chemical Communications55(2): 171-174.  https://pubs.rsc.org/en/content/articlelanding/2019/cc/c8cc06035e/unauth#!divAbstract
  4. Salari, S., et al. (2019). "In vitro evaluation of antioxidant and antibacterial potential of green synthesized silver nanoparticles using Prosopis farcta fruit extract." Iranian Journal of Pharmaceutical Research18(1): 430-445. http://ijpr.sbmu.ac.ir/article_2330.html

Written by Julie E Russell

January 2020