Surface polymer imprinted optical fibre sensor for dose detection of dabrafenib

Stable and reproducible MIP-ECL sensors for ultra-sensitive and accurate quantitative detection of Estrone

Estrone (E1), as an endogenous estrogen, has a variety of physiological functions in human body and is of great significance to human health. On the other hand, it is a widely distributed and highly disturbing environmental endocrine disruptor in water. Therefore, there is an urgent need to develop a sensitive, rapid, and inexpensive method for the on-site determination of E1, which is not only for clinical diagnosis and treatment, but also for the investigation and monitoring of endogenous estrogen pollution in environmental water. In this study, Ru(bpy)3 2+/MWCNTs/Nafion/gold electrodes were prepared by surface electrostatic adsorption and ion exchange. A molecularly imprinted membrane (MIP) with the capability to recognize E1 molecules was prepared by sol-gel method, and the electrodes were modified with MIP to form an electrochemical luminescence sensor (MIP-ECL). This method simultaneously possesses ECL's advantage of high sensitivity and MIP's advantage of high selectivity. Moreover, the addition of carboxylated multi-walled carbon nanotubes (MWCNT-COOH) improved the functionalization of the gold electrode surface and increased the binding sites of MIP. Meanwhile, the good conductivity of MWCNTs promoted electron transfer and further improved the sensitivity of the sensor. The sensor showed a wide linear interval in which the E1 concentrations can range from 0.1 μg/L to 200 μg/L, along with a high linear correlation coefficient (R 2 = 0.999). The linear regression equation of the sensor was Y = 243.64x-79.989, and the detection limit (LOD) was 0.0047 μg/L. To validate our sensor, actual samples were also measured by the reference method (LC-MS/MS), and it was found that the relative deviation of quantitative results of the two different methods was less than 4.1%. This indicates that the quantitative results obtained by this sensor are accurate and can be used for rapid in situ determination of E1 in clinical samples and environmental water.

Molecularly Imprinted Polymer-Based Biomimetic Systems for Sensing Environmental Contaminants, Biomarkers, and Bioimaging Applications

Molecularly imprinted polymers (MIPs), a biomimetic artificial receptor system inspired by the human body's antibody-antigen reactions, have gained significant attraction in the area of sensor development applications, especially in the areas of medical, pharmaceutical, food quality control, and the environment. MIPs are found to enhance the sensitivity and specificity of typical optical and electrochemical sensors severalfold with their precise binding to the analytes of choice. In this review, different polymerization chemistries, strategies used in the synthesis of MIPs, and various factors influencing the imprinting parameters to achieve high-performing MIPs are explained in depth. This review also highlights the recent developments in the field, such as MIP-based nanocomposites through nanoscale imprinting, MIP-based thin layers through surface imprinting, and other latest advancements in the sensor field. Furthermore, the role of MIPs in enhancing the sensitivity and specificity of sensors, especially optical and electrochemical sensors, is elaborated. In the later part of the review, applications of MIP-based optical and electrochemical sensors for the detection of biomarkers, enzymes, bacteria, viruses, and various emerging micropollutants like pharmaceutical drugs, pesticides, and heavy metal ions are discussed in detail. Finally, MIP's role in bioimaging applications is elucidated with a critical assessment of the future research directions for MIP-based biomimetic systems.

Differential Refractometric Biosensor for Reliable Human IgG Detection: Proof of Concept

A new sensing platform based on long-period fiber gratings (LPFGs) for direct, fast, and selective detection of human immunoglobulin G (IgG; Mw = 150 KDa) was developed and characterized. The transducer's high selectivity is based on the specific interaction of a molecularly imprinted polymer (MIPs) design for IgG detection. The sensing scheme is based on differential refractometric measurements, including a correction system based on a non-imprinted polymer (NIP)-coated LPFG, allowing reliable and more sensitive measurements, improving the rejection of false positives in around 30%. The molecular imprinted binding sites were performed on the surface of a LPFG with a sensitivity of about 130 nm/RIU and a FOM of 16 RIU^-1. The low-cost and easy to build device was tested in a working range from 1 to 100 nmol/L, revealing a limit of detection (LOD) and a sensitivity of 0.25 nmol/L (0.037 µg/mL) and 0.057 nm.L/nmol, respectively. The sensor also successfully differentiates the target analyte from the other abundant elements that are present in the human blood plasma.

Volatile Organic Compound Vapour Measurements Using a Localised Surface Plasmon Resonance Optical Fibre Sensor Decorated with a Metal-Organic Framework

A tip-based fibreoptic localised surface plasmon resonance (LSPR) sensor is reported for the sensing of volatile organic compounds (VOCs). The sensor is developed by coating the tip of a multi-mode optical fibre with gold nanoparticles (size: 40 nm) via a chemisorption process and further functionalisation with the HKUST-1 metal–organic framework (MOF) via a layer-by-layer process. Sensors coated with different cycles of MOFs (40, 80 and 120) corresponding to different crystallisation processes are reported. There is no measurable response to all tested volatile organic compounds (acetone, ethanol and methanol) in the sensor with 40 coating cycles. However, sensors with 80 and 120 coating cycles show a significant redshift of resonance wavelength (up to ~9 nm) to all tested volatile organic compounds as a result of an increase in the local refractive index induced by VOC capture into the HKUST-1 thin film. Sensors gradually saturate as VOC concentration increases (up to 3.41%, 4.30% and 6.18% in acetone, ethanol and methanol measurement, respectively) and show a fully reversible response when the concentration decreases. The sensor with the thickest film exhibits slightly higher sensitivity than the sensor with a thinner film. The sensitivity of the 120-cycle-coated MOF sensor is 13.7 nm/% (R² = 0.951) with a limit of detection (LoD) of 0.005% in the measurement of acetone, 15.5 nm/% (R² = 0.996) with an LoD of 0.003% in the measurement of ethanol and 6.7 nm/% (R² = 0.998) with an LoD of 0.011% in the measurement of methanol. The response and recovery times were calculated as 9.35 and 3.85 min for acetone; 5.35 and 2.12 min for ethanol; and 2.39 and 1.44 min for methanol. The humidity and temperature crosstalk of 120-cycle-coated MOF was measured as 0.5 ± 0.2 nm and 0.5 ± 0.1 nm in the humidity range of 50–75% relative humidity (RH) and temperature range of 20–25 °C, respectively.