Emerging and classical pollutants, such as antibiotics, pharmaceuticals, pesticides, dyes and heavy metals derived from human activity, currently pose serious threats to the environment and human health. Despite the grave danger posed by these pollutants, there is still no adequate monitoring of their presence in the environment. The regular determination of these contaminants in the environment can play a crucial role in the protection of human health and the preservation of ecosystems. New analytical techniques allow the reproducible quantification of analytes at very low concentration levels. Molecularly imprinted polymers (MIPs), with selective recognition, have also been combined with quantum dots (QDs) and suggested as valuable materials in the construction of optical sensors. Several strategies have been proposed for the selective detection of these pollutants in recent years. Rather than employing expensive, time-consuming standard analytical methods, fluorescent quantum dots coupled with molecularly imprinted polymers can be used for developing simple, rapid and highly selective analytical methods for the detection of these pollutants. This review presents a brief discussion on the application of tailor-made polymeric materials in tandem with quantum dots for the rational construction of efficient sensors capable of determining the presence of these pollutants in aquatic environments.

A polyurethane composite electrode modified with magnetic nanoparticles (mag; Fe3O4) coated with molecularly imprinted polymers (MIPs) was developed for the electrochemical determination of estradiol valerate. Chemical and morphological analyses of the mag-MIP were performed using scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDS), with the aim of characterizing this new material. The efficiency of adsorption of estradiol valerate by the mag-MIP was tested in binding experiments using an electrochemical method. For this, different electrodes (mag-MIP / graphite-epoxy composite (GEC), mag-non-imprinted polymer (NIP) / GEC, mag / GEC, and GEC) were evaluated by square-wave voltammetry (SWV). After 10 min at open circuit potential, increases in the current signal of 1.9, 2.1, and 3.0 times were obtained, comparing the electrochemical response of the mag-MIP / GEC sensor to the mag-NIP / GEC, mag / GEC, and GEC sensors, respectively. Under optimized conditions, the mag-MIP / GEC showed a linear concentration range for estradiol valerate of 5.0 × 10-7 to 7.5 × 10-4 mol L-1 and a limit of detection of 1.0 × 10-8 mol L-1. The proposed sensor was applied in the analysis of pharmaceutical, human urine, and river water samples. The recovery values determined using high performance liquid chromatography (HPLC)-UV and the electrochemical method were in agreement and were near 100%, demonstrating the reliability of the proposed method.

Two sensors were synthesized for the detection of free cyanide (CN-), based on silver sulfide nanoparticles (Np-Ag2S) supported on Multiwall Carbon Nanotubes (MWCNT) and hierarchical porous carbon (HPC). The Ag2S/HPC400 and Ag2S/MWCNT were characterized by physicochemical techniques such as Raman spectroscopy, X-Ray diffraction (XRD) and Scanning electron microscopy (SEM). These sensors were evaluated against the detection of free cyanide by potentiometry; the stability, reproducibility and linearity of each sensor were determined. A limit of detection of 3.34 µg L-1 and a limit of quantification of 11.05 µg L-1 for Ag2S/HPC400 sensor was obtained; while for the Ag2S/MWCNT sensor a limit of detection and limit of quantification value of 23.17 µg L-1 and 76.46 µg L-1 were obtained, respectively. The results show that the presence of carbonaceous materials with a hierarchical structure improves the limits of quantification and detection of the Ag2S/HPC400 sensor.

It is well known that selectivity of molecularly imprinted polymers (MIPs) depends on adequate choice of functional monomer before the experimental synthesis. Computational simulation seems to be an ideal way to produce selective MIPs. In this work, we have proposed the use of semi-empirical simulation to obtain the best monomer able to strongly interact with ciprofloxacin. Twenty functional monomers were evaluated through semi-empirical quantum chemistry method and three MIPs were synthesized using the monomers acrylamide (M5), acrylic acid (M4) and 1-vinylimidazole (M16), yielding the maximum adsorption capacities of 282.0, 223.8 and 202.5 μmol g−1, respectively, as predicted by the computational simulation. From competitive adsorption studies in the presence of structurally similar compounds, the MIP synthesized with acrylamide was found to possess higher specific selectivity factors (S) if compared to non-imprinted polymer (NIP), thus indicating good recognition selectivity for the ciprofloxacin.

O presente trabalho visa o desenvolvimento de um sensor biomimético para detecção de diclofenaco de sódio usando um eletrodo de carbono vítreo modificado com complexo 1,4,8,11,15,18,22,25-octabutoxi-29H,31H-ftalocianina de cobre(II) e nanotubos de carbono de parede múltipla funcionalizados (MWCNT-COOH). O sensor proposto foi avaliado em sistema em batelada usando tampão fosfato 0,1 mol L-1 (pH 7,5) como eletrólito de suporte. Uma resposta linear foi obtida na faixa entre 4,0 × 10-5 e 6,7 × 10-4 mol L-1, com uma sensibilidade de 6,1 × 10(5) (± 1,5 × 10(4)) µA L mol-1 e limite de detecção de 1,3 × 10-5 mol L-1 usando voltametria de onda quadrada. A seletividade foi estudada através da resposta do sensor na presença de outros fármacos. O sensor foi aplicado em formulações farmacêuticas e também em amostras de soro biológico através de estudos de recuperação. Quando acoplado a um sistema por injeção em fluxo (FIA), os melhores resultados foram obtidos aplicando o potencial de 0,5 V vs. Ag|AgCl|KCl sat, usando um volume de amostra injetado de 100 µL e uma vazão de 1,2 mL min-1. A faixa linear de resposta em fluxo foi entre 5,0 × 10-5 e 5,0 × 10-3 mol L-1, com uma sensibilidade de 1,6 × 10(4) (± 3,0 × 10²) µA L mol-1 e um desvio padrão relativo de 3.5%.

The present work aims the development of a biomimetic sensor for the detection of sodium diclofenac from a glassy carbon electrode modified with copper(II) 1,4,8,11,15,18,22,25-octabutoxy-29H,31H-phthalocyanine complex and functionalized multi-walled carbon nanotubes (MWCNT-COOH). The proposed sensor was evaluated in batch system using 0.1 mol L-1 phosphate buffer solution at pH 7.5 as electrolyte support. A linear response was obtained in the range of 4.0 × 10-5 and 6.7 × 10-4 mol L-1, with the sensitivity of 6.1 × 10(5) (± 1.5 × 10(4)) µA L mol-1 and detection limit of 1.3 × 10-5 mol L-1 using square wave voltammetry. The selectivity was studied by the sensor response in the presence of other drugs. The sensor was applied to pharmaceutical formulations and also to biological serum samples by recovery studies. When coupled to a flow injection system (FIA), the best results were obtained by applying the potential of 0.5 V vs. Ag|AgCl|KCl sat, using an injected volume of the sample of 100 µL and a flow of 1.2 mL min-1. The linear response range in flow was between 5.0 × 10-5 and 5.0 × 10-3 mol L-1, with a sensitivity of 1.6 × 10(4) (± 3.0 × 10²) µA L mol-1and a relative standard deviation of 3.5%.