Simple and Sensitive Molecularly Imprinted Polymer – Mn-Doped ZnS Quantum Dots Based Fluorescence Probe for Cocaine and Metabolites Determination in Urine

Abstract

A new molecularly imprinted polymer (MIP)-based fluorescent artificial receptor has been prepared by anchoring a selective MIP for cocaine (COC) on the surface of polyethylene glycol (PEG) modified Mn-doped ZnS quantum dots (QDs). The prepared material combines the high selectivity attributed to MIPs and the sensitive fluorescent property of the Mn-doped ZnS QDs. Simple and low cost methods have therefore been optimized for assessing cocaine abuse in urine by monitoring the fluorescence quenching when the template (COC) and also metabolites from COC [benzoylecgonine (BZE) and ecgonine methyl ester (EME)] are present. Fluorescence quenching was not observed when performing experiments with other drugs of abuse (and their metabolites) or when using nonimprinted polymer (NIP)-coated QDs. Under optimized operating conditions (1.5 mL of 200 mg L(-1) MIP-coated QDs solution, pH 5.5, and 15 min before fluorescence scanning) two analytical methods were developed/validated. One of the procedures (direct method) consisted of urine sample 1:20 dilution before fluorescence measurements. The method has been found to be fast, precise, and accurate, but the standard addition technique for performing the analysis was required because of the existence of matrix effect. The second procedure performed a solid phase extraction (SPE) first, avoiding matrix effect and allowing external calibration. The limits of detection of the methods were 0.076 mg L(-1) (direct method) and 0.0042 mg L(-1) (SPE based method), which are lower than the cutoff values for confirmative conclusions regarding cocaine abuse.

SERS-Based Molecularly Imprinted Plasmonic Sensor for Highly Sensitive PAH Detection

“…MIPs are hence three-dimensional supramolecular smart materials with remarkable molecular recognition properties . Compared to other recognition systems, MIPs have become attractive in many fields such as purification and separation, chemo/biosensing, − artificial antibodies, drug delivery, and catalysis and degradation, owing to their high physical stability, straightforward and low-cost preparation, and remarkable robustness . However, the use of MIPs for sensing applications still has some drawbacks such as converting the binding event into a measurable and quantifiable signal, and hence, it could be cumbersome to perform a multiplex analysis.…”

Molecularly Imprinted Polymers

“…The binding efficiency is monitored by the decrease in signal, and reports of as much as 93% quenching have been reported. 54 The sensitivity of fluorescence measurements is evident in this type of sensor; LODs as low as 44 nM have been reported. 55 Two examples of the use of this technique are included in Table 2.…”

The Recent Advances of Fluorescent Sensors Based on Molecularly Imprinted Fluorescent Nanoparticles for Pharmaceutical Analysis

“…The fluorescent nanoparticles could be directly used, or used after proper modification. The modification could be achieved by silylation [21,22] , or being treated with oleic acid [23] , polyethyleneimine [24] , or polyethyleneglycol [25,26] , aiming to provide functional groups or compatibility with synthetic medium for better embedding the fluorescent nanoparticles in the MIP; (2) Polymerization. The crosslinking agent was added to the pre-assembled system, and the polymerization proceeded to form a highly-crosslinked polymer triggered by the initiator or catalyzed by the catalyst; (3) Removal of the template.…”