Facile preparation of polydopamine-coated imprinted polymers on the surface of SiO2 for estrone capture in milk samples

Rapid Analysis of Estrogens in Meat Samples by High Performance Liquid Chromatography with Fluorescence Detection

A novel reagent named 4-(N-methyl-1,3-dioxo-benzoisoquinolin-6-yl-oxy)benzene sulfonyl chloride (MBIOBS-Cl) for the determination of estrogens in food samples by high-performance liquid chromatography (HPLC) with fluorescence detection has been developed. Estrogens could be easily labeled by MBIOBS-Cl in Na2CO3-NaHCO3 buffer solution at pH 10.0. The complete labeling reaction for estrogens could be accomplished within five minutes, the corresponding derivatives exhibited strong fluorescence with the maximum excitation and emission wavelengths at 249 nm and 443 nm, respectively. The derivatization conditions, such as the molar ratio of reagent to estrogens, derivatization time, pH, temperature, and buffers were optimized. Derivatives were sufficiently stable to be efficiently analyzed by HPLC with a reversed-phase Agilent ZORBAX 300SB-C18 column with a good baseline resolution. Excellent linear correlations were obtained for all estrogen derivatives with correlation coefficients greater than 0.9998. Ultrasonic-Assisted extraction was used to optimize the extraction of estrogens from meat samples with a recovery higher than 82%. The detection limits (LOD, S/N = 3) of the method ranged from 0.95 to 3.3 μg· kg-1. The established method, which is fast, simple, inexpensive, and environment friendly, can be successfully applied for the detection of four steroidal estrogens from meat samples with little matrix interference.

Selective Analysis of Progesterone in Cosmetic Samples Based on Molecularly Imprinted Solid-Phase Extraction and High-Performance Liquid Chromatography

The illegal addition of progesterone to cosmetics could cause serious adverse reactions and pose a serious threat to human health. In this work, a simple, fast and sensitive method was developed by combining molecularly imprinted solid-phase extraction and high-performance liquid chromatography (MISPE-HPLC) for the selective determination of progesterone in cosmetics. Chitosan-modified silica is used as the carrier to provide binding sites for the effective conjugation of the target. The obtained molecularly imprinted polymers exhibited excellent adsorption capacity (36.2 mg·g-1), good selectivity and fast mass transfer rate for progesterone. Meanwhile, the prepared MISPE column could eliminate the interference of co-existing substances. Combined MISPE with HPLC, a selective and effective method for detecting progesterone in different cosmetics was achieved. Under the optimum conditions, the established MISPE-HPLC method was successfully used for the detection of progesterone in real samples. The linear range of this method was 1 to 200 μg·mL-1 with a limit of detection of 0.016 μg·mL-1. Therefore, this method could be used for the selective and effective detection of progesterone in different cosmetic samples with complex substrates. We provided an alternative method for the detection of illegal additions in cosmetics.

Isolation of Phenolic Compounds from Raspberry Based on Molecular Imprinting Techniques and Investigation of Their Anti-Alzheimer's Disease Properties

Alzheimer's disease is the most common neurodegenerative disease, characterized by memory loss and cognitive dysfunction. Raspberry fruits contain polyphenols which have antioxidant and anti-inflammatory properties. In this study, we used molecular imprinting technology to efficiently isolate phenolic components from the raspberry ethyl acetate extracts. Six phenolic components (ellagic acid, tiliroside, kaempferol-3-o-rutoside, gallic acid, ferulic acid and vanillic acid) were identified by UPLC-Q-TOF-MS analysis. Molecular docking was used to predict the anti-inflammatory effects and anti-Alzheimer's potential of these isolated compounds, which showed a good binding ability to diseases and related proteins. However, the binding energy and docking fraction of ellagic acid, tiliroside, and kaempferol-3-o-rutoside were better than those of gallic acid, ferulic acid and vanillic acid. Additionally, by studying the effects of these six phenolic components on the LPS-induced secretion of inflammatory mediators in murine microglial (BV2) cells, it was further demonstrated that they were all capable of inhibiting the secretion of NO, IL-6, TNF-α, and IL-1β to a certain extent. However, ellagic acid, tiliroside, and kaempferol-3-o-rutoside have better inhibitory effects compared to others. The results obtained suggest that the phenolic components extracted from ethyl acetate extracts of raspberry by molecularly imprinted polymers have the potential to inhibit the progression of Alzheimer's disease.

Methacrylic functionalized hybrid carbon nanomaterial for the selective adsorption and detection of progesterone in wastewater

Progesterone, an endocrine-disrupting chemical, has been frequently detected in wastewater for decades, posing a serious threat to ecological and human health. However, it is still a challenge to achieve the effective detection of progesterone in complex matrices water samples. In this study, a novel adsorbent CNT@CS/P(MAA) was prepared by grafting methacrylic polymers on the surface of modified carbon nanomaterials. Compared with other reported materials, the hybrid carbon nanomaterial could selectively identify the progesterone in the complex industrial pharmaceutical wastewater, and its adsorption performance is almost independent of the pH and environmental temperature. In addition, this nanomaterial could be reused with a good recovery rate. The prepared nanomaterials were characterized by transmission electron microscopy, Fourier transform infrared spectroscopy, X-ray diffraction, nitrogen adsorption and desorption experiments, and thermogravimetric analysis. The results confirmed that the methacrylic polymers and chitosan layer were successfully grafted on the surface of carbon nanotubes. Adsorption isotherms, adsorption kinetics, and selectivity tests showed that CNT@CS/P(MAA) had a high adsorption capacity (44.45 mg·g-1), a fast adsorption rate and a satisfied selectivity for progesterone. Then, CNT@CS/P(MAA) was used as solid phase extraction sorbent and combined with HPLC to enrich progesterone from the wastewater samples. Under the optimum conditions, a good linearity was obtained with the correlation coefficient was 0.9998, and the limit of detection was 0.003 ng·mL-1. Therefore, this method could be used for the selective and effective detection of progesterone in industrial wastewater with complex substrates and provided a new method for the detection of progesterone in other environmental waters.

Assessment of cross-reactivity in a tailor-made molecularly imprinted polymer for phenolic compounds using four adsorption isotherm models

Cross-reactivity is an important feature of molecularly imprinted polymers (MIPs), and is central to successful use of a pseudo-template in molecular imprinting. The adsorption and cross-reactivity of a molecularly imprinted polymer (MIP) designed for recognition of phenols from water was assessed using four different isotherm models (Langmuir (LI), Freundlich (FI), Langmuir-Freundlich (L-FI), and Brunauer, Emmett, and Teller (BET)). The L-FI model succeeded in explaining the cross-reactivity behavior through the total number of binding sites, the affinity constants and heterogeneity indices of the small phenols (phenol (ph), 2-methylphenol (2-MP), 3-methylphenol (3-MP), 2-chlorophenol (2-CP), 2,4-dimethylphenol (DMP), 2,4-dichlorophenol (DCP), 4-chloro-3-methylphenol (CMP)) with evidence that the phenols compete for binding sites based on their hydrophobicity as well as π-π, π-σ and dipole-dipole intermolecular forces. The recognition of the large phenols (2,4,6-trichlorophenol (TCP), pentachlorophenol (PCP), 4-teroctylphenol (4-OP), 4-nonylphenol (4-NP), which have much higher binding affinities than the smaller phenolic compounds, was explained with the BET isotherm model that predicts that multiple layers adsorb to the adsorbed monolayer. The adsorption behavior with MIPs is also shown to be superior to corresponding non-imprinted polymers and applicability of MIPs for trace analysis is highlighted.

Comparison of Four Adsorption Isotherm Models for Characterizing Molecular Recognition of Individual Phenolic Compounds in Porous Tailor-Made Molecularly Imprinted Polymer Films

A molecularly imprinted polymer (MIP) film using catechol as the template was designed for adsorption of a range of phenols from water. Four different isotherm models (Langmuir (LI), Freundlich (FI), Langmuir-Freundlich (L-FI), and Brunauer, Emmett, and Teller (BET)) were used to study the MIP adsorption of five phenolic compounds: phenol (Ph), 2-methylphenol (2-MP), 3-methylphenol (3-MP), 2-chlorophenol (2-CP), and 4-teroctylphenol (4-OP). Each model was evaluated for its fit with the experimental data, and key parameters, including a number of binding sites and binding site energies, were compared. Though the LI, L-FI, and BET models showed good agreement for estimation of the number of binding sites and affinity for most adsorbates, no single model was suitable for all. The LI and L-FI models gave the best fitting statistics for the Ph, 2-MP, 3-MP, and 2-CP. The recognition of 4-OP, which has much higher binding affinities than the smaller phenolic compounds not attributable to hydrophobicity alone, was explained only by the BET model, which indicates the formation of multilayers. The BET model failed only with phenol. MIPs also showed higher adsorption capacities and improved homogeneity over the analogous non-imprinted polymers.