Measurement artifacts identified in the UV-vis spectroscopic study of adduct formation within the context of molecular imprinting of naproxen

• Type: Article in International Scientific Journal
• Date: 2016

Authors

Perez, M (Author) Other; Riccardo Concu (Author) FCUP; Ornelas, M (Author) Other; Natalia N D S Cordeiro (Author) FCUP; Manuel Azenha (Author) FCUP; Silva, F (Author) FCUP

Journal

Title: Spectrochimica Acta - Part A: Molecular and Biomolecular Spectroscopy

Vol. 153

Pages: 661-668

ISSN: 1386-1425

Publisher: Elsevier

Indexing

ISI Web of Knowledge - 14 Citations

Scopus - 15 Citations

Other information

Authenticus ID: P-00G-Q1N

DOI: 10.1016/j.saa.2015.10.005

Abstract (EN): The ultraviolet-visible spectroscopy has been assessed as a technique for the evaluation of the strength of template-precursor adduct in the development of molecular imprints of the non-steroidal anti-inflammatory drug naproxen (NAP). The commonly employed approach relies on the collection of UV spectra of drug + precursor mixtures at different proportions, the spectra being recorded against blanks containing the same concentration of the precursor. The observation of either blue or red band-shifts and abatement of a major band are routinely attributed to template-precursor adduct formation. Following the described methodology, the precursors 1-(triethoxysilylpropyl)-3-(trimethoxysilylpropyl)-4,5-dihydroimidazolium iodide (AO-DHI+) and 4-(2-(trimethoxysilyl)ethyl)pyridine (PETMOS) provoked a blue-shift and band abatement effect on the NAP spectrum. Molecular dynamics simulations indicated a reasonable affinity between NAP and these precursors (coordination numbers 033 for AO-DHI+ and 0.18 for PETMOS), hence showing that NAP-precursor complexation is in fact effective. However, time dependent density functional theory (TD-DFT) calculations of the spectra of both free and precursor-complexed NAP were identical, thus providing no theoretical basis for the complexation-induced effects observed. We realized that the intense spectral bands of AO-DHI+ and PETMOS (at around 265 nm) superimpose partially with the NAP bands, and the apparent "blue-shifting" in the NAP spectra when mixed with AO-DHI + and PETMOS was in this case a spurious effect of the intense background subtraction. Therefore, extreme care must be taken when interpreting other spectroscopic results obtained in a similar fashion.

Language: English

Type (Professor's evaluation): Scientific

No. of pages: 8