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The application of substrates composed of microporous materials and gold nanoparticles enables bacterial communication processes to be observed at very early stages, at which the number of bacteria is still very low to cause infections, according to research conducted by groups led by Luis Liz-Marzán at both CIC biomaGUNE (Donostia-San Sebastián) and the University of Vigo.
The work, published in the prestigious journal Nature Materials, has given rise to three plasmonic substrates with different features, offering advantages ranging from subcutaneous detection to high spatial resolution, and opens up the potential for diagnosis of bacterial infections in a general fashion. As Luis Liz-Marzán, Ikerbasque Research Professor and Scientific Director at CIC biomaGUNE, explains, “one such example could be the use of implants in areas where surgery has been performed and there is a risk of infection. Similar applications can be envisaged in dental implants, whereby the risk of infection could be pre-detected”.
The research shows the potential for identifying those molecules which use bacteria to communicate with each other. This communication process, known as quorum sensing, is used by these microorganisms to ascertain colony density (the number of individuals in any one colony) and consequently to take diverse actions, often related to bacterial infections. Dr. Liz-Marzán adds: “The work presents the application of substrates composed of microporous materials and gold nanoparticles which enable ultrasensitive detection of quorum sensing markers”.
Five years of research
After five years of research, trace amounts of pyocyanin, a molecule involved in the communication of bacteria known as Pseudomonas aeruginosa, which in turn collude in serious diseases such as cystic fibrosis and cause serious problems in hospital facilities, have been discovered.
The work leading to the article “Detection and imaging of quorum sensing in Pseudomonas aeruginosa biofilm communities by surface-enhanced resonance Raman scattering” began over five years ago with considerable funding from the European Research Council through an ERC Advanced Grant. The research work, taken forward on a joint basis by the groups at CIC biomaGUNE and the University of Vigo, has its roots in the experience gained by Liz -Marzán’s research group on the synthesis and organisation of gold nanoparticles and their plasmonic properties (electron oscillations in response to visible or infrared light).
To clarify the scientific dimension of the findings, Liz-Marzán explains that … “what this work reveals is that the directed organisation of nanoparticles, together with the presence of a porous matrix, enables ultrasensitive detection in real conditions of bacterial proliferation. This is the first time this technique has been applied for real-time detection of the appearance of so-called bacterial biofilms with no impact on the biofilm formation process itself. The nanoparticles themselves act as sensors, whilst the porous material acts as a filter to stop large-size molecules such as fats or proteins from hindering detection”.
The main technique used in this research has been Surface Enhanced Raman Scattering (SERS). This technique provides ultrasensitive and specific identification of molecules, down to the single-molecule level. The challenge for the application of this technique is in designing amplifier substrates containing optimally organised nanoparticles to improve the spectroscopic signal.
On a personal level, Luis Liz-Marzán recognises that… “this work is the culmination of a long study through which knowledge and know-how related to chemical synthesis, physical characterisation and even theoretical prediction have been practically applied in the field of biomedicine and have opened up numerous future lines of development. The satisfaction of having proved the hypothesis put forward when project funding was originally requested is also to be highlighted”.
About CIC biomaGUNE
The Centre for Cooperative Research in Biomaterials (CIC biomaGUNE), located in the Donostia-San Sebastián Technology Park, conducts cutting-edge research at the interface between Chemistry, Biology and Physics, and particularly on the properties of molecular level biological nanostructures and their biomedical applications.