New potentiometric sensor based on molecularly imprinted nanoparticles for cocaine detection

Here we present a potentiometric sensor for cocaine detection based on molecularly imprinted polymer nanoparticles (nanoMIPs) produced by the solid-phase imprinting method. The composition of polymers with high affinity for cocaine was optimised using molecular modelling. Four compositions were selected and polymers prepared using two protocols: chemical polymerisation in water and UV-initiated polymerisation in organic solvent. All synthesised nanoparticles had very good affinity to cocaine with dissociation constants between 0.6nM and 5.3nM. Imprinted polymers produced in organic solvent using acrylamide as a functional monomer demonstrated the highest yield and affinity, and so were selected for further sensor development. For this, nanoparticles were incorporated within a PVC matrix which was then used to prepare an ion-selective membrane integrated with a potentiometric transducer. It was demonstrated that the sensor was able to quantify cocaine in blood serum samples in the range of concentrations between 1nM and 1mM

Selective vancomycin detection using optical fibre long period gratings functionalised with molecularly imprinted polymer nanoparticles

An optical fibre long period grating (LPG) sensor modified with molecularly imprinted polymer nanoparticles (nanoMIPs) for the specific detection of antibiotics is presented. The operation of the sensor is based on the measurement of changes in refractive index induced by the interaction of nanoMIPs deposited onto the cladding of the LPG with free vancomycin (VA). The binding of nanoMIPs to vancomycin was characterised by a binding constant of 4.3 ± 0.1 × 10(-8) M. The lowest concentration of analyte measured by the fibre sensor was 10 nM. In addition, the sensor exhibited selectivity, as much smaller responses were obtained for high concentrations (∼700 μM) of other commonly prescribed antibiotics such as amoxicillin, bleomycin and gentamicin. In addition, the response of the sensor was characterised in a complex matrix, porcine plasma, spiked with 10 μM of VA

Molecularly Imprinted High Affinity Nanoparticles for 4-Ethylphenol Sensing

A novel sensor for 4-ethylphenol (4EP) was developed based on molecularly imprinted nanoparticles produced via the solid phase imprinting method. The nanoparticles were immobilised on the surface of a gold electrode previously modified with a self assembled monolayer of lipoic acid coupled to EDC/NHS ((1-ethyl-3-[dimethylaminopropyl]carbodiimide)/N-hydroxysuccinimide). Each step of the process was characterised by electrochemical impedance spectroscopy and cyclic voltammetry. The electrode was used to selectively determine 4EP by differential pulse voltammetry; a quite remarkable sensitivity improvement was observed in the nanoparticle-modified electrode in reference to the non modified bare gold electrode