With its fatal effects, cancer is still one of the most important diseases of today’s world. The underlying fact behind this scenario is most probably due to its late diagnosis. That is why the necessity for the detection of different cancer types is obvious. Cancer studies including cancer diagnosis and therapy have been one of the most laborious tasks. Since its early detection significantly affects the following therapy steps, cancer diagnosis is very important. Despite researchers’ best efforts, the accurate and rapid diagnosis of cancer is still challenging and difficult to investigate. It is known that electrochemical techniques have been successfully adapted into the cancer diagnosis field. Electrochemical sensor platforms that are brought together with the excellent selectivity of biosensing elements, such as nucleic acids, aptamers or antibodies, have put forth very successful outputs. One of the remarkable achievements of these biomolecule-attached sensors is their lack of need for additional labeling steps, which bring extra burdens such as interference effects or demanding modification protocols. In this review, we aim to outline label-free cancer diagnosis platforms that use electrochemical methods to acquire signals. The classification of the sensing platforms is generally presented according to their recognition element, and the most recent achievements by using these attractive sensing substrates are described in detail. In addition, the current challenges are discussed.

2,4,6-Trinitrophenol (TNP) is explosive, toxic, ecological, and a human health hazard and is resistant to degradation. It can cause symptoms such as headache, loss of appetite, dizziness, fever, nausea, diarrhea, and vomiting when inhaled. In this study, we aimed to develop a new halloysite nanotube anchored with pyrene moieties (HNT@Py) for the sensitive determination of TNP in soil, wastewater, and food samples using fully aqueous media. The HNT@Py was characterized structurally, morphologically, and thermally by using FTIR, UV-vis, XRD, TGA, fluorescence, SEM, and TEM analyses. The detection conditions for the assay were investigated and optimized, including competitive species, incubation time, sensor concentration, photostability, and selectivity. The limit of detection (LOD) and limit of quantification (LOQ) for TNP were found to be 14.00 nmol L^-1 and 42.00 nmol L^-1 in the linear response of 0.04 μmol L^-1 and 0.60 μmol L^-1 (R ² = 0.9962), respectively. Validation of the current method was performed using the spike/recovery test and HPLC analyses, and it was subsequently utilized to successfully detect TNP with fluorescence in soil, food, and water samples. According to the obtained results, the suggested assay is dependent on the "turn-off" emission of HNT@Py with the PET mechanism between electron-deficient NACs and the electron-rich pyrene moieties. The sensor was found to be easy to use, extremely sensitive, and reliable in rapidly identifying TNP in real samples, displaying excellent flexibility and resilience. Additionally, detection membranes with regular morphology were obtained by the electrospinning method using HNT@Py nanostructures dispersed in the PCL matrix, and RGB changes were determined via a smartphone application.

Iron and copper ions detection are very important for environmental and biological processes. In this work, novel pyrene-functionalized Schiff base chitosan (Chit-Pyr) was synthesized, and this hybrid material was used as a “turn-off” fluorescence sensor for the detection of Fe2+, Fe3+, and Cu2+ ions. FTIR, UV-Vis, TGA, and SEM were used to examine for structural, thermal, and morphological properties of Chit-Pyr. This sensor exhibited a selectivity towards Fe2+, Fe3+, and Cu2+ ions among several common metal cations in the DMF dispersion. The results obtained that the proposed “turn off” fluorescence sensing mechanism of Chit-Pyr was simple and sensitive for the determination of Fe2+, Fe3+, and Cu2+ ions.