Ultra-sensitive optical fiber sensor based on intermodal interference and temperature calibration for trace detection of copper (II) ions

Overview of Optical Biosensors for Early Cancer Detection: Fundamentals, Applications and Future Perspectives

Conventional cancer detection and treatment methodologies are based on surgical, chemical and radiational processes, which are expensive, time consuming and painful. Therefore, great interest has been directed toward developing sensitive, inexpensive and rapid techniques for early cancer detection. Optical biosensors have advantages in terms of high sensitivity and being label free with a compact size. In this review paper, the state of the art of optical biosensors for early cancer detection is presented in detail. The basic idea, sensitivity analysis, advantages and limitations of the optical biosensors are discussed. This includes optical biosensors based on plasmonic waveguides, photonic crystal fibers, slot waveguides and metamaterials. Further, the traditional optical methods, such as the colorimetric technique, optical coherence tomography, surface-enhanced Raman spectroscopy and reflectometric interference spectroscopy, are addressed.

A New Sensing Material Based on Tetraaza/SBA15 for Rapid Detection of Copper(II) Ion in Water

A novel rapid and sensitive optical sensor for Cu2+ ion detection based on 5,5,7,12,12,14-hexamethyl-1,4,8,11-tetraazacyclotetradeca-7,14-dienium dibromide (TL) immobilized on Santa Barbara Amorphous (SBA-15) has been successfully developed. The inner and outer space of SBA15 allowed a high capacity of TL compound to immobilize onto it. FESEM (Field Emission Scanning Electron Microscopy) analysis was performed to confirm the morphology of TL-SBA15, while FTIR (Fourier Transform Infrared Spectroscopy) was utilized to confirm the interaction of TL−SBA15. A binding study of TL compound towards Cu2+ ion was performed via UV-vis solution study and binding titration. The stoichiometric binding ratio and binding constant value Kb of TL towards Cu2+ ion was 1:1 and 2.33 × 103 M−1, respectively. The optical reflectance sensor based on the TL compound is selective to Cu2+ ion and demonstrated a linear response over a Cu2+ ion concentration range of 1 × 10−7 M to 2 × 10−5 M, with a detection limit (LOD) of 1.02 × 10−7 M (R2 = 0.99) and fast response time of < 1 min. It showed high reproducibility, with a relative standard deviation (RSD) obtained at 0.47%. This optical sensor is reusable up to five consecutive times on Cu2+ ion by using 0.1 M EDTA with a pH of 6 as a regeneration solution, with a reversibility RSD value of 0.79%. The developed optical sensor provides a rapid and sensitive tool for Cu2+ ion detection in teabag samples, and the results align with those obtained by the ICP-MS standard method.