Synthesis and Evaluation of Molecularly Imprinted Polymers for the Determination of Di(2-ethylhexyl) Phthalate (DEHP) in Water Samples.

A molecularly imprinted polymer for the selective determination of Di(2-ethylhexyl) phthalate (DEHP) in water was synthesized and evaluated. This was accomplished by the use of sodium methacrylate as the monomer, toluene as a porogen, ethylene glycol dimethacrylate as a crosslinker, azobisisobutyronitrile as initiator and DEHP as a template molecule to generate the selectivity of the polymer for the compound, as well as synthesizing non-imprinted polymers. Three different polymerization approaches were used, emulsion, bulk and co-precipitation, the polymers obtained by emulsion presented a high retention rate reaching 99%. The method was able to pre-concentrate DEHP in water samples up to 250 times. To evaluate the applicability of the method, concentrations in fortified and bottled water were assessed using our polymer and determining DEHP concentrations by gas chromatography with mass spectrometry. Reported concentrations in bottled water were 12.1 µg/L, well above reference values established by the U.S. Environmental Protection Agency.

Development and evaluation of ciprofloxacin local controlled release materials based on molecularly imprinted polymers.

The aim of this study was the molecular imprinting polymers (MIPs) assessment as a controlled release system of ciprofloxacin. The MIPs synthesis was performed by three different methods: emulsion, bulk, and co-precipitation. Lactic acid (LA) and methacrylic acid (MA) were used as functional monomers and ethylene glycol dimethacrylate as crosslinker. Also, nonimprinted polymers (NIPs) were synthesized. MIPs and NIPs were characterized by scanning electron microscopy, Fourier Transform Infrared Reflection, specific surface area, pore size, and release kinetics. Their efficiency against Staphylococcus aureus and Escherichia coli, and their cytotoxicity in dermal fibroblast cells were proven. Results show that MIPs are mesoporous materials with a pore size between 10 and 20 nm. A higher adsorption with the co-precipitation MIP with MA as a monomer was found. The release kinetics proved that a non-Fickian process occurred and that the co-precipitation MIP with LA presented the highest release rate (90.51 mg/L) in 8 h. The minimum inhibitory concentration was found between 0.031 and 0.016 mg/L for Staphylococcus aureus and between 0.004 and 0.031 mg/L for the Escherichia coli. No cytotoxicity in cellular cultures was found; also, cellular growth was favored. This study demonstrated that MIPs present promising properties for drug administration and their application in clinical practice.

Molecularly imprinted polymers (MIPs) as efficient catalytic tools for the oxidative degradation of 4-nonylphenol and its by-products.

Water pollution is a current global concern caused by emerging pollutants like nonylphenol (NP). This endocrine disruptor cannot be efficiently removed with traditional wastewater treatment plants (WTPs). Therefore, this work aimed to evaluate the adsorption influence of molecularly imprinted polymers (MIPs) on the oxidative degradation (ozone and ultraviolet irradiations) of 4-nonylphenol (4-NP) and its by-products as a coadjuvant in WTPs. MIPs were synthesized and characterized; the effect of the degradation rate under system operating conditions was studied by Box-Behnken response surface design of experiments. The variables evaluated were 4-NP concentration, ozone exposure time, pH, and MIP amount. Results show that the MIPs synthesized by co-precipitation and bulk polymerizations obtained the highest retention rates (> 90%). The maximum adsorption capacities for 4-NP were 201.1 mg L-1 and 500 mg L-1, respectively. The degradation percentages under O3 and UV conditions reached 98-100% at 120 s of exposure at different pHs. The degradation products of 4-NP were compounds with carboxylic and ketonic acids, and the MIP adsorption was between 50 and 60%. Our results present the first application of MIPs in oxidation processes for 4-NP, representing starting points for the use of highly selective materials to identify and remove emerging pollutants and their degradation by-products in environmental matrices.

Environmental endocrine disruptor concentrations in urine samples from Mexican Indigenous women.

The Indigenous communities in Mexico show significant degrees of vulnerability to pollution due to the lack of knowledge of health risks, traditions, low levels of support, and restricted access to healthcare. As a result, exposure to environmental endocrine disruptors increases in these populations through plastic components or indoor air pollution. Therefore, the aim of the study was to evaluate the exposure to phthalate metabolites, 1-hydroxypyrene, and bisphenol A through biomonitoring data from indigenous Mexican women. A total of 45 women from the Tocoy community in San Luis Potosí, Mexico, were included. Urine samples were analyzed for Bisphenol A and 4 phthalate metabolites by ultra-performance liquid chromatography couples to tandem mass spectrometry; additionally, the 1-hydroxypyrene concentrations were evaluated by high-performance liquid chromatography coupled to a fluorescence detector. Among the main pollution sources were the use of plastic containers and burning garbage (98-100%). Indigenous women presented an exposure of 100% to mono-2-ethyl phthalate, mono-n-butyl phthalate, and 1-hydroxypyrene, with a median (25th-75th percentiles) of 17,478 (11,362-37,355), 113.8 (61.7-203.5), and 1.2 (0.9-1.7) µg/g creatinine, respectively. The major findings show urinary mono-2-ethyl phthalate concentrations higher than those measured from other studies. Therefore, these results show an impressive exposure to di(2-ethylhexyl) phthalate in Indigenous women. The current study reflects the absence of regulatory policies in marginalized populations. It highlights the need to design strategies that mitigate exposure and the importance of biological monitoring to evaluate and prevent health risk associated with exposure to environmental endocrine disruptors.

Design and application of molecularly imprinted polymers for adsorption and environmental assessment of anti-inflammatory drugs in wastewater samples.

In this study, a series of molecularly imprinted polymers (MIPs) have been synthesized using separately diclofenac, naproxen, and ibuprofen as templates with three different polymerization approaches. Two functional monomers, methacrylic acid (MAA) and 2-vinylpyridine (2-VP), were tested and ethylene glycol dimethacrylate (EGDMA) was used as crosslinker; also, template-free polymers (NIPs) were synthesized. It was found that the MIP with the highest retention percentage for diclofenac was the one prepared by the emulsion approach and with MAA (98.3%); for naproxen, the one prepared by the bulk polymerization with MAA (99%); and for ibuprofen, the one synthesized by bulk with 2-VP (97.7%). These three MIPs were characterized by scanning electron microscopy, thermogravimetric test, Fourier transform infrared, specific area measurements, and surface charge. It was found that the emulsion method allowed particle size control, while the bulk method gave heterogeneous particles. The three evaluated MIPs exhibited thermal stability up to 300 °C, and it was observed that 2-VP confers greater stability to the material. From the BET analysis, it was demonstrated that the MIPs and NIPs evaluated are mesoporous materials with a pore size between 10 and 20 nm. In addition, the monomer influenced the surface charge of the material, since the MAA conferred an acidic point of zero charge (PZC), while the 2-VP conferred a PZC of basic character. Through adsorption isotherms, it was determined  that there is a higher adsorption capacity of the MIPs at acidic pH following a pseudo-second-order kinetic model. Finally, the MIPs were used to determine the non-steroidal anti-inflammatory drugs (NSAIDs) understudy in San Luis Potosí, México, wastewater, finding concentrations of 0.642, 0.985, and 0.403 mg L-1 for DCF, NPX, and IBP, respectively.