A simple and straightforward technique for coating microplate wells with molecularly imprinted polymer nanoparticles (nanoMIPs) to develop assays similar to the enzyme-linked immunosorbent assay (ELISA) is presented here for the first time. NanoMIPs were synthesized by a solid-phase approach with an immobilized vancomycin (template) and characterized using Biacore 3000, dynamic light scattering, and electron microscopy. Immobilization, blocking, and washing conditions were optimized in microplate format. The detection of vancomycin was achieved in competitive binding experiments with a horseradish peroxidase-vancomycin conjugate. The assay was capable of measuring vancomycin in buffer and in blood plasma within the range of 0.001-70 nM with a detection limit of 0.0025 nM (2.5 pM). The sensitivity of the assay was 3 orders of magnitude better than a previously described ELISA based on antibodies. In these experiments, nanoMIPs have shown high affinity and minimal interference from blood plasma components. Immobilized nanoMIPs were stored for 1 month at room temperature without any detrimental effects to their binding properties. The high affinity of nanoMIPs and the lack of a requirement for cold chain logistics make them an attractive alternative to traditional antibodies used in ELISA.

No abstract

Here, we present a technique for the determination AQ:1 AQ:2 1 of the gaseous oxygen concentration inside packed food. It is 2 based on the use of a luminescent membrane sensitive to O 2 that 3 is optically excited and read by a smartphone. The flash of the 4 smartphone along with an optical filter is used as the light source 5 for the optical stimulation of the membrane. The luminescence 6 generated, which is quenched by the surrounding gaseous oxygen, 7 is registered by the rear camera of the same device. The response 8 parameter is defined by combining the registered intensities at 9 two different wavelength ranges corresponding to the emission 10 and the absorption peaks of the sensitive membrane. Thanks to 11 this novel response parameter, the sensitivity is increased and, 12 more importantly, the thermal dependence of the membrane 13 is significantly reduced. This approach allows the use of a 14 luminescent O 2-sensitive membrane for intelligent packaging 15 with no need of any associated electronics for its excitation 16 and reading. This means that an oxygen sensor is developed, 17 where a luminescent compound acts as an indicator, therefore 18 combining the advantages of both schemes, that is, the simplicity 19 and reduced cost of indicators with the high sensitivity and 20 accuracy of selective sensors.

In this work, we present a new system for the determination of dissolved carbon dioxide (from 7.2 ppm to 425.6ppm) in aqueous environments. Microfluidic technology has been incorporated in sensor design to reduce the volume of samples and reagents. Moreover, a detection system has been integrated in the chip, consisting of a white light-emitting diode as a light source and a high-resolution digital colour sensor as the detector, which are able to detect changes in colour produced by the reaction of the sensing chemistry and carbon dioxide in water.The optimised parameters found for the system are: flow rate 0.6 mL•min -1 , integration time 30 s and the time for pumping of solutions was 3 min, obtaining a LOD of 7.2 ppm. The CO2 response, reproducibility, precision, and stability of the sensing chemistry have been studied and compared with those obtained using benchtop instrumentation (i.e. a spectrophotometer), obtaining good agreement.