Detection of DNA hybridization with the help of graphene
Graphene has shown promise for a number of applications, including medical and biosensing applications. A scientific team from Graphenea, in collaboration with scientists from CNRS and SENSIA SL, demonstrated the application of graphene as a DNA biosensor to kill hazardous bacteria.
Graphene is a two-dimensional allotrope of carbon, which is a potential candidate for a number of human health applications, in part because of its unique response to light. For instance, graphene shows incredibly high absorption for a single atomic layer, absorbing 2.3% of incoming light over the entire visible region of the spectrum.
The light absorption by graphene oxide is even higher, and the incident light is converted into heat. The heat generated by nanoparticles has been employed to kill cancer cells and graphene oxide was also used for the same purpose in recent studies. However, Graphenea’swork targeted hazardous bacteria such as Escherichia coli (E. coli) for the first time, using the same approach.
E. coli is generally associated with urinary tract infections. It reproduces rapidly like any other pathogen, causing major health risks to the people and community at large. Most bacterial infections lead to conditions such as tissue damage and chronic inflammation, which are further intensified due to the growth of microorganisms in continuous “biofilms”.
Bacteria have become antibiotic resistant in the past few decades and consequently the risk associated with biofilm-related infections has further increased. Bacteria’s antibiotic resistance is associated with the misuse and overuse of antibiotics.
Using Nanotechnology for Bacterial Destruction
The increasing antibiotic resistance of bacteria has led to various alternative strategies for destroy bacteria being considered. Recent nanotechnology developments have paved the way for employing near-infrared (NIR) light-absorbing gold nanostructures to treat bacterial infections by irradiating with focused laser pulses at appropriate wavelengths.
Localized heat energy can be efficiently generated from the light absorbed by the gold nanostructures for the hyperthermic destruction of pathogens. The light absorbed by the gold nanostructures is in the NIR (700-900nm) region of the spectrum, which traverses biological tissues safely. However, the toxicity of the surfactant chemical utilized in the gold nanorod production is a concern.
Use of Reduced Graphene Oxide
Reduced Graphene Oxide (rGO) is a good absorber of light, and is a potential material for use in photothermal therapy. rGO-based nanocomposites have been considered for cancer theranostics, but this method has rarely been used for pathogen destruction. This is even more surprising considering the widespread commercial availability of graphene oxide.
Graphenea explored the possibility of destroying E. coli pathogens in its study featured in the Journal of Materials Chemistry B. Reduced graphene oxide (rGO-PEG- NH2) and Au nanorods (Nrs) coated with rGO-PEG-NH2 were used to destroy the pathogens by laser irradiation. The rGO-PEG coating serves a dual purpose by mitigating the toxicity of Au NRs and improving the overall photo-thermal process and so the temperatures reachable.
In this paper, Graphenea showed 99% bacterial killing efficiency at low concentrations (20-49mg/ml) in a water solution, demonstrating the potential of reduced graphene oxide as an effective anti-pathogen agent.
In another research project as part of the same partnership, scientists have demonstrated the possibility of using a graphene layer on gold as an effective sensor of DNA hybridization with unprecedented attomolar sensitivity. The paper, titled “Highly Sensitive Detection of DNA Hybridization on Commercialized Graphene-Coated Surface Plasmon Resonance Interfaces,” has been published in the Analytical Chemistry journal.
In this work, a commercial (SENSIA SL) surface plasmon resonance instrument was used to demonstrate the sensitivity of DNA detection at very low concentrations of a few attomoles. Here, Graphenea’s high-quality CVD graphene was grown on metal and transferred onto the detection chip.
Graphenea makes every effort to extend the boundaries of the knowledge and applications of graphene through intensive partnership with the greatest scientists of the world.
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