Förster resonance energy transfer (FRET)-based biosensors are being fabricated for specific detection of biomolecules or changes in the microenvironment. FRET is a non-radiative transfer of energy from an excited donor fluorophore molecule to a nearby acceptor fluorophore molecule. In a FRET-based biosensor, the donor and acceptor molecules are typically fluorescent proteins or fluorescent nanomaterials such as quantum dots (QDs) or small molecules that are engineered to be in close proximity to each other. When the biomolecule of interest is present, it can cause a change in the distance between the donor and acceptor, leading to a change in the efficiency of FRET and a corresponding change in the fluorescence intensity of the acceptor. This change in fluorescence can be used to detect and quantify the biomolecule of interest. FRET-based biosensors have a wide range of applications, including in the fields of biochemistry, cell biology, and drug discovery. This review article provides a substantial approach on the FRET-based biosensor, principle, applications such as point-of-need diagnosis, wearable, single molecular FRET (smFRET), hard water, ions, pH, tissue-based sensors, immunosensors, and aptasensor. Recent advances such as artificial intelligence (AI) and Internet of Things (IoT) are used for this type of sensor and challenges.

Interleukins (ILs) are a major subclass of cytokines acting as molecular messengers playing role in immune system responses via a cascade of signaling pathways. Belonging to the cytokine family, the ILs play a crucial role in the theranostics of various diseases. Their abnormal expression leads to the development of various diseases such as cancer, neurodegenerative diseases, allergies, asthma, autoimmune diseases, and other physiological abnormalities. This paves the path of exploring the ILs for the development of sensitive and efficient biosensors and promoting them for clinical testing in a wide array of diseases. Further, detecting the level of ILs is very important for their early diagnosis and their progression within the body, and simultaneously their possible immunotherapeutic approaches. To achieve this goal, multidisciplinary scientific approaches involving immunology, electrochemistry, nanotechnology, photometry, etc. are already being put into action. The advancements in nanoscience and nanotechnology are aiding the development of highly sensitive biosensors for ILs detection. This review focuses on giving a detailed description of all the presently discovered ILs and their role in various diseases. Simultaneously, it also discusses the various electrochemical biosensors that can be employed for the detection of ILs in body fluids. Moreover, the role of nanomaterials in electrochemical biosensing is also discussed in this review.

This proposed work reports the development of in-house made conductive ink-based screen-printed electrodes (SPEs) for label-free detection of oral cancer biomarkers. Carbon ink synthesis includes graphite powder, gum arabic, and water. The selectivity test of the fabricated SPE involves immobilizing antibodies specific to biomarkers and challenges with redox-active interference, other serum molecules, and non-target biomarkers. Three different biomarkers, cytokeratin-19 fragment (CYFRA 21-1), interleukin 8 (IL-8), and tumor protein p53 (TP-53), act as target entities for the detection of oral cancer in patients' samples (serum, N = 28, and saliva, N = 16) at an early stage. The standard technique enzyme-linked immunosorbent assay (ELISA) was employed to estimate the concentration of the biomarkers in serum and saliva samples. SPEs contain amine (–NH₂) functional groups involved in covalent bonding with the carboxyl (–COOH) groups of antibody molecules. These immunosensors exhibited remarkably lower detection limits of 829.5 pg mL⁻¹, 0.543 pg mL⁻¹, and 1.165 pg mL⁻¹, and excellent sensitivity of 0.935 μA mL pg⁻¹ cm⁻¹, 0.039 μA mL pg⁻¹ cm⁻¹, and 0.008 μA mL pg⁻¹ cm⁻¹ for CYFRA 21-1, IL-8, and TP-53 biomarkers, respectively. This sensing platform does not require any functionalization for biomolecule immobilization. Thus, it is a cost-effective, disposable, flexible, miniaturized, and sensitive strip to detect oral cancer biomarkers.

Targeted nanomaterials are at the forefront of advancements in nanomedicine due to their unique and versatile properties. These include nanoscale size, shape, surface chemistry, mechanical flexibility, fluorescence, optical behavior, magnetic and electronic characteristics, as well as biocompatibility and biodegradability. These attributes enable their application across diverse fields, including drug delivery. This review explores the fundamental characteristics of nanomaterials and emphasizes their importance in clinical applications. It further delves into methodologies for nanoparticle programming alongside discussions on clinical trials and case studies. We discussed some of the promising nanomaterials, such as polymeric nanoparticles, carbon-based nanoparticles, and metallic nanoparticles, and their role in biomedical applications. This review underscores significant advancements in translating nanomaterials into clinical applications and highlights the potential of these innovative approaches in revolutionizing the medical field.