Cancer biomarker and neurotransmitters recognition by molecularly imprinted xero-gels

In this paper, a library of molecularly imprinted xero-gels has been synthesized against the cancer biomarker 5-hydroxyindole acetic acid (5-HIAA) and against the neurotransmitter serotonin (SER) as the target molecules, using different alkoxy-silane precursors. The xero-gel composition, in particular its hydrophobic/hydrophilic balance, is of major importance for adequate recognition and determination of 5-HIAA and SER. The recognition ability of the imprinted xero-gel library is studied using a dynamic flow injection analysis system (FIA system) and the response of each imprinted xero-gel is compared with that for blank materials prepared in the absence of templates. The approach is simple, no-time consuming (no clean-up steps to remove proteins or related molecules), highly sensitive (a detection limit of 5.5 × 10−7 M 5-HIAA was found by the standard addition method), reproducible and the calibration graph (y = 5.0 × 106 × (M) + 4.98, r2 = 0.999) is linear up to 2 × 10−4 M 5-HIAA. Results demonstrate that a “dummy” imprinted xero-gel against serotonin is highly selective for recognition of 5-HIAA. The use of this “dummy” material as recognition phase in an optosensing device is described, while practical application of the system is demonstrated by determining 5-HIAA in synthetic urine samples.