Drug Detection in Biological Specimens: Recent Colorimetric Methods

Abstract

Recently, the detection approaches based on the metal nanoparticles (NPs) have attracted more and more attention due to their great extinction coefficient and strong surface plasma resonance properties. This report focuses on the present status of drug detection with metal NPs as ultrasmall labels in colorimetric-based methods. Although progresses have been emerged in drug detection, much work remains to be done to overcome the great challenges on sample preparation of complicated biological fluids. Plasmonic NPs can be combined with other existing functional groups to produce frameworks with novel multifunctional surface plasmon resonance for generating optical platform in drug detection. With their continued progress, we believe that making high quality and multifunctional plasmonic materials will play an important role in the drug detection and quantification in biological samples. Many important disciplines involving human health are dealing with the analysis of drugs present in living organisms or biological fluids. Biological samples are difficult to handle owing to their inherent complexity and, sometimes, sample preparation processes such as tryptic digestion make them even more complex. However, in the case of simpler matrices such as exhaled breath condensate, the direct injection of sample to analytical instruments is possible [1][2][3]. This complexity hinders the reliable analysis in two ways. First, most biological fluids are not amendable with analytical instruments since all biological samples consist of a vast range of ions, proteins, lipids, carbohydrates and so on, and cannot be injected to analytical devices. Second, highly abundant interfering compounds disturb the identification and quantification of trace analytes at subnanogram per milliliter levels.A bioanalytical strategy consists of two integral stages:r Sample preparation (treatment/cleanup/extraction) of the target analyte from its complex biological matrix; r Separation, detection and quantification of the analyte.Common technologies for drug determination in body fluids including ELISA, chromatographic and electrophoretic-based methods suffer from several limitations in bioanalytical laboratories. Owing to the complex matrix of most biological specimens, they rely on time-and labor-consuming sample purification. Moreover, sophisticated instruments such as MS are not affordable by many of the laboratories and require effective extraction approaches [4][5][6][7][8]. It is noteworthy that the sensitivity of some of these technologies is not adequate for detecting the required levels of target analyte. Therefore, there is still a great demand to develop inexpensive, fast, user-friendly and easy-to-operate technologies.The association of nanotechnology with medical treatment, including therapeutic drug monitoring, pharmacokinetic and pharmacodynamic studies has provided a new concept in drug detection. Label-free detection systems with little to no sample preparation is more appreciated [9]. Colorimetric methods use the intrinsic advant...

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