Nanosensors can be used in the detection, monitoring, and treatment of cancer. Due to their size and specificity, they can help in detecting specific biomarkers associated with cancer. For instance, a gold nanoparticle-based nanosensor array was developed to detect volatile organic compounds from exhaled breath of patients suffering from lung, breast, colorectal, and prostate cancers. Nanosensors based on CNTs can be used to detect cancerrelated biomolecules in trace amounts. Highly sensitive sensors developed using silicon nanowires, silver nanowires, etc. can also be used to detect cancers. These nanosensors can detect subtle changes in electric conductivity upon their interaction with cancer biomarkers. Magnetic nanoparticles (MNPs) such as superparamagnetic iron oxide nanoparticles (SPIONs) typically made from magnetite (Fe3O4) are used to develop magnetic nanosensors for cancer nanotheranostics. For certain specific applications, magnetic nanoparticles are conjugated with immune components to develop immunomagnetic nanosensors that can be used for detecting and imaging cancer stem cells (CSCs). For instance, a study explained the detection of glioblastoma CSCs using an anti-CD133 monoclonal antibody (mAb) coupled to magnetic nanoparticles. Nanosensors in pathogen and infectious diseases detection: Owing to their miniature size and ease of portability nanosensors play a pivotal role in the detection of pathogens including bacteria, fungi, viruses, and protozoans with high sensitivity and selectivity. Interactions between the functionalized nanomaterials and pathogenic species can induce changes in the physical, chemical, and electrical properties of sensors. These altered signals can be measured and quantified for detecting/sensing pathogens. Carbon-based nanosensors, 163 metallic nanoparticles, and metal-oxide-based nanoparticles 165 are used for bacterial detection and therapy. Certain metallic nanoparticle-based nanosensors, such as silver and gold experience localized changes in SPR. Nanobiosensors are also being developed for fungi and viruses, especially for the COVID-19 virus. Specialized nanosensors are developed by coating nanomaterials with pathogen-specific recognition elements such as enzymes, aptamers, proteins, and peptides. In certain cases, quantum dot nanosensors are engineered to bind with specific biomolecules resulting in changes in fluorescence, bioluminescence, chemiluminescence, and photoelectrochemical biosensors. These nanosensors are highly tunable and their emission signals can be controlled by altering their sizes. In another example, graphene-based nanosensors utilize graphene's high surface area and excellent conductivity to detect pathogens for instance graphene field-effect transistors (GFETs) are used for ultrasensitive detection. In addition, advancements in this field have led to the development of nanopore-based sensors for pathogen detection, 172 microfluidic nanosensors for high throughput pathogen detection, and magnetic nanoparticles conjugated with aptamers or antibodies 174 for robust pathogen detection to name a few.