In an article published in Nano Letters, the application of optical nanopore sensing techniques for quantitative analysis is examined.
Study: Optical Nanopore Sensors for Quantitative Analysis. Image Credit: ktsdesign/Shutterstock.com
Applications of Biosensors
Biosensors can evaluate analytes in biological samples, allowing them to differentiate between diseased and healthy stages.
On the other hand, several clinically useful biomarkers exist in biological samples in small amounts that need ultrasensitive biosensors to be measured.
In recent years, biosensors with the ability to detect analytes at the single-molecule level have aroused interest for these applications.
Instead of evaluating a signal change caused by a group of molecules, these sensors record "events" caused by a single molecule's engagement with the sensor.
The attractiveness of these tools for quantitative examination arises from their single-molecular resolution, which enables analysis at the ultimate detection limit.
Based on the detected signal, single-molecule biosensors also have the ability to provide details on the sample's heterogeneity as well as distinguish between particular and nonspecific activities.
Finally, measuring single molecules can also make adjusting the sensor easier or even unnecessary.
Nanopores have evolved as an interesting group of single-molecule biosensors in recent decades.
A nm sized space in an impenetrable membrane divides two reservoirs of electrolyte in these sensors.
Ions pass through the nanopore when an electric field is provided across the membrane resulting in a measured ionic current.
Electrophoretic effects can be utilized to attract biomolecules into and out of the pore when an electric field is applied across the membrane.
The flow of ions is affected by the translocation of a biomolecule through the pore, which changes the ionic current.
DNA and Protein Sequencing
In this study, impacts on the ionic current through the nanopore when a DNA molecule crosses the pore, due to the variable shape and size of every nucleobase, are examined.
The sequence of a peptide's amino acid can now be examined using this recently extended method.
The readout of data held within nanoscale electrochemistry, enzymology, polymeric molecules and protein analysis are all examples of applications for nanopore sensors that go beyond protein sequencing and DNA.
Optical Nanopore Sensing
One approach relies on observing the changes in the optical signal to identify the diffusion of biomolecules when they pass through a nanopore.
These optical sensing technologies use broad microscopy to allow independent detection of translocations through every nanopore within an array depending on the signal's position within the domain.
This greatly enhances the quantity of data that may be gathered in order to abstract analytes at sub picomolar concentrations.
Moreover, optical nanopore sensing strategies may have significant benefits over ionic current-based detection, such as increased signal-to-noise ratio, the ability to operate at high sampling frequencies, sensitivity to molecular characteristics not possible with ionic current-based detection, and the ability to detect low electrolyte concentrations
Over the last decade, advancements in optical nanopore sensor optimization have led to greater attention on the devices' usages.
These devices are ideal for analyzing analytes at extremely low concentrations in a quantitative manner. Furthermore, multiple studies have lately confirmed the identification of clinically important biomarkers in biological materials.
DNA methylation, circulating tumor DNA, microRNA and proteins have all been detected.
The application of molecular carriers, which eliminated the requirement to explicitly label the analyte and thus simplified sample processing, was especially promising in this field.
Applications of Optical Nanopore Sensors
Optical-based nanopore sensing and ionic current methods are suitable for various quantitative evaluation applications.
Specifically, the potential to miniaturize nanopore sensors based on ionic current suggests that these devices could be useful for point-of-care examinations.
Moreover, optical nanopore sensing techniques require comparatively large and powerful optical equipment that makes these devices a better choice for use in specialized areas. This can involve the usage of these sensors for early illness detection and disease surveillance in pathology labs.
Researchers can also utilize such gadgets to perform basic biological research.
Development of optical nanopore sensing strategies must be continued in order to attain this goal. This involves developing commercially feasible methodologies for fabricating these gadgets as well as boosting biomarker quantification procedures to utilize arrays of nanopores of high density.
If this can successfully be accomplished, optical nanopore sensors have considerable scope as a diverse, ultrasensitive technology for biomarker quantification.
Fried, J. P., Wu, Y., Tilley, R. D., & Gooding, J. J. (2022). Optical Nanopore Sensors for Quantitative Analysis. Nano Letters. Available at: https://doi.org/10.1021/acs.nanolett.1c03976