The significant increase in the use (and misuse) of antibiotics allows microbes to evolve into antibiotic-resistant strains. Drug-resistant bacteria have become a major health threat: In the EU alone, there are 400,000 patients a year suffering from antibiotic-resistant infections. One multidrug-resistant superbug is Pseudomonas aeruginosa, which causes various types of infections. It is often embedded within a self-produced biofilm, where bacteria are well protected and are extremely resistant to any antibiotic treatment.

Khin Yin Win and Ming-Yong Han, A*STAR, Singapore, Lianhui Zhang, National University of Singapore, and colleagues developed an alternative photothermal treatment for drug-resistant infections. The team conjugated gold nanocrosses to antibodies, which bind to their specific surface antigens on the infectious bacteria. Here the antibodies target a secretion protein of P. aeruginosa. The antibodies on the nanocrosses bind to surface antigens on the infectious bacteria. The anisotropically branched nanocrosses (pictured) exhibit a strong near-infrared (NIR) absorption and hence generate heat quickly upon irradiation.

NIR-irradiation for five minutes at a power density of 3.0 W/cm² was sufficient to destroy the bacteria as well as their biofilms. According to the researchers, the approach can be easily shifted to target other bacteria by simply exchanging the antibodies.

• Effective Targeted Photothermal Ablation of Multidrug Resistant Bacteria and Their Biofilms with NIR-Absorbing Gold Nanocrosses,
  Choon Peng Teng, Tielin Zhou, Enyi Ye, Shuhua Liu, Leng Duei Koh, Michelle Low, Xian Jun Loh, Khin Yin Win, Lianhui Zhang, Ming-Yong Han,
  Adv. Healthcare Mater. 2016.
  DOI: 10.1002/adhm.201600346