Golden Nanostars
Biomedical engineers from Duke University have developed a method for simultaneous detection of various specific microRNAs in tissue samples without the need for labeling or amplification of nucleic acids. This method can be used for early detection of cancer and other diseases without complex, time-consuming and expensive processes and special laboratory equipment.
microRNAs are short RNA molecules that bind to the matrix RNA and prevent them from transmitting instructions for protein production. They can regulate the expression of genes, changing the implementation of certain biological functions as a result. More than 2000 microRNAs have been found in humans, which affect development, differentiation, growth and metabolism.
Some microRNAs are associated with improper regulation of biological functions, resulting in oncological and other diseases. These discoveries have increased research interest in the use of microRNAs as biomarkers of diseases and therapeutic targets. Due to the very small number of microRNAs present in body tissue samples, traditional methods of studying them require genetic amplification processes.
These technologies work in well-equipped laboratories and large-budget scientific research, which can last months or years, but they are not suitable for rapid diagnosis in the clinic.
To fill this gap in accessibility, a group from Duke University created silver-plated gold nanostars.
Gold star nanoparticles have several spikes that can amplify electromagnetic waves – this is the uniqueness of the special shape of the particles, which the creators used to generate clear signals about the presence of various microRNAs.
The design of the nanosensors causes the labeled molecule to move very close to the peaks of the nanostar if a certain part of the target RNA is recognized and captured. The laser is triggered by the sensor signal, and the effect of the lightning removal of the nanostar rays causes the labeled molecule to glow brightly, informing the researchers about the capture of the target RNA.
The molecule with the label (orange dot) is located at a distance from the nanostar due to the spacer (blue). If there is a corresponding RNA sequence in the sample, it removes the spacer, causing the DNA strand to twist (orange), bringing the molecule with the label closer to the nanostar. The graph on the right shows a burst of signal caused by amplified light emission.
Under laser excitation, this label emits very weak light, but the shape of the star and the effect of a combination of individual reactions caused by gold nanoparticles and silver coating enhances the glow by several million times, facilitating their detection.
In this clinical trial to test the platform, the team demonstrated the detection of miR-21 microRNA specific to early stage esophageal cancer in 17 endoscopic biopsy samples. The inverse molecular sentinel (iMS) method with stellate nanoparticles showed diagnostic accuracy.
In this case, the use of one miR-21 is enough to distinguish healthy tissue samples from cancer samples, but for other diseases, simultaneous detection of several microRNAs may be required for reliable diagnosis, which is why researchers are so excited about the effectiveness of the new nanobiosensors. This method can provide a diagnostic alternative to histological analysis and PCR and simplify the process of cancer diagnosis
A patent for the invention has been obtained, it is planned to start research to detect colon cancer in blood samples even before the tumor forms.
Article by B.M.Crawford et al. Plasmonic Nanobiosensors for Detection of microRNA Cancer Biomarkers in Clinical Samples is published in the journal Analyst.
Aminat Adzhieva, portal "Eternal Youth" http://vechnayamolodost.ru based on Duke materials: Silver-Plated Gold Nanostars Detect Early Cancer Biomarkers.