Glutathione-stabilized fluorescent gold nanoclusters show label-free high binding affinity for the bacterial biofilms but not for the planktonic bacteria
Daniil S. Chumakov, 1,
Stella S. Evstigneeva, 1
Roman S. Tumskiy , 1
Andrey M. Burov, 1
Nikolay G. Khlebtsov, 1,2
1 Institute of Biochemistry and Physiology of Plants and Microorganisms, Russian Academy of Sciences (IBPPM RAS), Saratov, Russia
2 Saratov State University, Saratov, Russia
Abstract
It is well-known, that in natural environments, most bacteria form biofilms by encapsulating themselves in a extracellular matrix, containing polysaccharides, proteins, nucleic acids and lipids. The study of biofilms is of great importance in public health and agriculture. It has been argued that 75 % of microbial infections in the body are caused by bacteria growing as biofilm. Thus, there is a need for the development of simple, rapid diagnostic biofilm imaging methods that will enable monitoring of the efficiency of antibiofilm treatments. Fluorescent gold nanoclusters (Au NC) are considered as prospect fluorescent tags for bioimaging. Au NC display a series of significant superiorities: wide Stokes shift, high photostability, high chemical stability, low toxicity, simple synthesis and low susceptibility to blinking. In our work we have used two types of Au NC, stabilized by glutathione and bovine serum albumin, for bacterial biofilm imaging. To the best of our knowledge, this is the first time that fluorescent Au Nc have been applied for such purpose. Orange-emitting glutathione-stabilized Au NC have been found to bind with single-species biofilms of 4 bacteria (gram-negative and gram-positive) without specific targeting. Surprisingly, glutathione-stabilized Au NC did not bind with planktonic cultures of the same bacteria. Red-emitting bovine serum albumin-stabilized Au NC did not show any biofilm staining. That might occur due to the absence of affinity of nanoclusters with biofilm or fluorescence quenching of Au NC when interacting with biological substrate. Viability tests did not reveal significant antibacterial activity of these bioorganic nanoclusters towards the bacterial cultures. The results obtained might be used to create a test system based on fluorescent nanoclusters for the rapid assessment of the amount of biomass in biofilms, as well as to develop technologies for biofilm staining in clinical settings.
Aknowledgement: This work was supported by a grant from the Russian Science Foundation no. 18-14-00016-П
Speaker
Daniil S. Chumakov
Institute of Biochemistry and Physiology of Plants and Microorganisms, Russian Academy of Sciences (IBPPM RAS), Saratov, Russia
Russia
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