Nanoscale sensors are devices which employ nanotechnology to detect and react to specific chemical, physical, or biological stimulus at the level of the nanoscale. This article discusses the operating principle, classification, and applications of numerous nanoscale sensors in life sciences.
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What Are Nanoscale Sensors?
The global market for nanoscale sensors has grown significantly over several decades. The industry has witnessed novel applications for nanoscale sensors in medical diagnosis and other life science sectors.
Nanoscale sensors have also provided us with remarkable resolution, sensitivity, and specificity for analyzing biological systems.
A nanoscale sensor is a sensing system having at least a single dimension of one hundred nanometers (nm), collecting and converting nanoscale information into data useful for analysis.
They readily interact with substances at the nanoscale (such as proteins, for example) and identify special processes that are invisible at the macroscale.
Many techniques, such as molecular self-assembly, bottom-up assembly (e.g., chemical vapor deposition) and top-down lithography, have been presented today to develop nanoscale sensors.
How Do Nanoscale Sensors Work?
A nanoscale sensor is made up of four parts: a sensor, analyte, transducer, and detector.
Nanoscale sensors typically work by detecting electrical changes in sensor materials. The analyte reacts when it diffuses from the sample to the sensor's surface.
This changes the transducer surface's chemical and physical characteristics, which then affects the transducer surface's electronic or optical properties, generating an electrical signal that can be detected.
Classification of Nanoscale Sensors
Nanoscale sensors can be characterized and classified based on their component materials, detection targets, and data transmission signals.
There are four main types: electrochemical, optical, calorimetric, and acoustic. Nanomaterials, including metallic nanoparticles, nanotubes, are employed in developing nanoscale sensors.
The detection targets of nanoscale sensors can include peptides, antibodies, biological molecules, enzymes, aptamers, and more.
The optimum sensing probe (device) for bio-molecular applications must meet numerous criteria. For example, it should be readable with high temporal and spatial resolution. Aside from the quantity of interest, it must be biocompatible and unaffected by changes in other factors.
What Are the Applications of Nanoscale Sensors?
The vital need for nanoscale sensors facilitates a wide range of everyday activities, which explains how this technology is effectively applied in many sectors to meet ongoing demands.
Nanoscale sensors, for example, are applied in public settings to monitor virus and disease transmission. Other applications include in-body networks that evaluate blood, disease, and breath in real-time. Furthermore, these technologies can easily be linked to wearable health and environmental trackers.
Nanoscale sensors can also be utilized for early disease detection, medication research and discovery, bio-data monitoring, disease status and treatment effectiveness identification, biomolecule detection, and high-resolution genome-phenome connection elucidation. The following are some of the uses for nanoscale sensors in life sciences.
Early Disease Detection
Early illness detection is one of the most promising uses for nanoscale sensors in life sciences. Researchers have invented nanoscale sensors that detect specific biomarkers linked to illnesses, including cancer.
Nanoscale sensors and highly specific nanomaterial-based devices have been constructed for cancer to detect biomarkers, circulating tumor cells (CTCs), or tumor-derived vessels that are released early on from the tumor into the blood, potentially changing the disease's morbidity and mortality.
Ann-Katrine Jakobsen et al. applied nanosensors to examine the TDP1 (Tyrosyl-DNA phosphodiesterase 1) and TOP1 (Topoisomerase I) processes in cryo-sections of non-small cell lung cancer (NSCLC) tissue specimens collected at Aarhus University Hospital, which included twenty-four paired (tumor and non-tumor) tissue samples.
Their findings revealed that in NSCLC, both TDP1 and TOP1 were elevated in tumor tissue relative to surrounding non-tumor tissue.
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Monitor Cellular Processes
Our knowledge of cellular functions could be improved by applying nanoscale sensors, which offer strong, adaptable instruments for tracking bio-molecular targets and signaling pathways within living cells.
Kasili et al. demonstrated the usability of a novel optical sensor with a nano-probe for monitoring the initiation of the mitochondrial apoptosis pathway in a living cell (MCF-7) by sensing caspase-9 enzymatic activity, which denotes the beginning of apoptosis in the cells.
Caspase-9 activity in a single live MCF-7 cell was successfully detected by quantitatively measuring changes in fluorescence signals between nonapoptotic and apoptotic cells caused by photodynamic therapy.
Neurological Studies: Neurochemical Imaging
Neurochemicals, including serotonin (S-HT) and dopamine (DA) have been linked to a range of illnesses, including Parkinson's disease, epilepsy, and addiction. Detecting and monitoring these chemicals in vivo and in vitro has become critical for treating such diseases.
The ability to detect DA and S-HT at low concentrations by electrochemical methods has been made possible by their electro-active nature. Numerous electrode configurations and methodologies have been documented.
Chandrashekar et al. used a carbon slurry (paste) electrode to electro-polymerize L-arginine, resulting in a biopolymer that could detect DA, ascorbic acid (AA), and uric acid (UA).
Li et al. tweaked glassy carbon electrodes (GCEs) with single-walled carbon nanotubes (SWCNTs), achieving a DA detection limit of 50 nM and peak current ranging from 5 to 100 μM.
Detection of Analytes in Biofluids
Blood is the most used bio-fluid for diagnosis, which is followed by urine, and saliva that has lately gained substantial attention, for example, in relation to quick diagnostic tests for COVID-19. Tears, perspiration (sweat), and interstitial fluid (ISF) are other bio-fluids available.
Xu et al. developed a new method for optical glucose detection based on an H2O2-triggered sol-gel transition and modified gold nanoparticles.
The aggregation of AuNPs occurred by cascade reactions: the glucose oxidase (GOx) enzyme generated H2O2, which, in the presence of Fe2+, resulted in AuNP aggregation and a visible color change.
Commercially Available Nanoscale Sensor for Pre-clinical Drug Development
Lysosomal accumulation of lipids in liver macrophages is a useful biomarker that is affected in various conditions, such as drug-induced phospholipidosis, nonalcoholic steatohepatitis (NASH) and lysosomal storage diseases.
LipidSense, Inc. is a biotech company creating an optical sensor to detect lipid accumulation. Their most advanced sensor operates in vivo, allowing for longitudinal assessments of medication effectiveness and toxicology in the same animal while lowering the cost, time, and number of mice required in pre-clinical drug research.
Future Outlook
Nanoscale sensors have found many applications in the disciplines of life sciences, medicine, and the medical sector. They can be used to alleviate human problems and heal diseases because they can easily adapt to their surroundings.
They offer various advantages over their microcontractors, including decreased power consumption, increased sensitivity, and less analyte concentration. However, they continue to confront hurdles that prevent wider implementation.
It is difficult to manufacture nanoscale sensors on a wide scale while maintaining consistent performance and keeping costs low. In biomedical applications, nanoscale sensors must be biocompatible and safe.
By tackling these issues, researchers may continue to improve nanoscale sensors, broadening their scope and enabling their widespread use in a variety of applications.
References and Further Reading
Khazaei, M., et al. (2023). Nanosensors and their applications in early diagnosis of cancer. Sensing and Bio-Sensing Research, vol. 41, p. 100569. doi.org/10.1016/J.SBSR.2023.100569.
Sigaeva, A., et al. (2019). Optical Detection of Intracellular Quantities UsingNanoscale Technologies. Accounts of Chemical Research, vol. 52, no. 7, p. 1739. doi.org/10.1021/ACS.ACCOUNTS.9B00102
Lime Therapeutics. Available at: https://www.limetherapeutics.com/ (accessed Jan. 16, 2024).
Vo-Dinh, T. et al. (2009). Applications of Fiberoptics-Based Nanosensors to Drug Discovery. Expert Opinion on Drug Discovery, vol. 4, no. 8, p. 889. doi.org/10.1517/17460440903085112.
Meyyappan, M. (2015). Nano biosensors for neurochemical monitoring. Nano Convergence, vol. 2, no. 1, pp. 1–6. doi.org/10.1186/S40580-015-0049-3/FIGURES/5.
Boselli, L., et al. (2021). Nanosensors for Visual Detection of Glucose in Biofluids: Are We Ready for Instrument-Free Home-Testing?. Materials, 2021, Vol. 14, Page 1978, vol. 14, no. 8, p. 1978. doi.org/10.3390/MA14081978
Javaid, M., et al. (2021). Exploring the potential of nanosensors: A brief overview. Sensors International, vol. 2, p. 100130. doi.org/10.1016/J.SINTL.2021.100130.
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