Fluorescent Chemo sensor nano-materials for Cancer bio-markers signalling: Towards development of non-invasive early detection strategies

Although current cancer treatment technologies have advanced quickly, the patient's chance of recovering is still poor. Early detection enhances cancer prognosis and can considerably lower cancer-related fatalities. The most popular approaches for cancer diagnosis at the moment are tumor imaging and specimen biopsy. Unfortunately, these techniques are only capable of locating large tissue regions with malignant tumors. They eventually involve removing a solid specimen from the tumor area, which is then examined for particular biomarkers and the tumor's genetic makeup to ascertain whether its cancerous or otherwise. The removal of tissue is invasive and uncomfortable for the patient, and in some cancers that are challenging to surgically remove, it may not be possible. Furthermore, a solid sample cannot be used repeatedly and the surgical procedures and the subsequent analysis are costly and time-consuming. On top of these, safety may not be guaranteed, for example, when sampling tumors near important blood arteries, in sensitive parts of the brain, or individuals with significant co-morbidities. In such circumstances, these strategies may be clinically impractical. In such scenarios, non-invasive liquid biopsy becomes a significant option that may solve these limitations, where the biomarkers are studied in non-solid biological tissue samples, mostly blood. It offers several benefits including minimal risk, non-invasiveness, lower cost, and faster diagnosis. Recent developments in various fluorescent nano-biosensors for early detection of cancer, together with synthesis, surface functionalization and detection methodologies in the various tumor microenvironments will be discussed in this review. Several nanomaterials, including gold nanoparticles (AuNPs), magnetic nanoparticles, quantum dots (QDs), and carbon nanotubes (CTNs) will be explored. Emphasis on robustness, sensitivity, stability, linear detection ranges, and detection limits for these materials will also be highlighted. This review will be useful to researchers interested in understanding the chemistry and biochemical processes of these interesting materials in the identification of various cancer biomarkers.