Current trends of functional monomers and cross linkers used to produce molecularly imprinted polymers for food analysis.

Molecularly imprinted polymers (MIPs) as artificial synthetic receptors are in high demand for food analysis due to their inherent molecular recognition abilities. It is common practice to employ functional monomers with basic or acidic groups that can interact with analyte molecules via hydrogen bonds, covalent bonds, and other interactions (π-π, dipole-ion, hydrophobic, and Van der Waals). Therefore, selecting the appropriate functional monomer and cross-linker is crucial for determining how precisely they interact with the template and developing the polymeric network's three-dimensional structure. This study summarizes the advancements made in MIP's functional monomers and cross-linkers for food analysis from 2018 to 2023. The subsequent computational design of MIP has been thoroughly explained. The discussion has concluded with a look at the difficulties and prospects for MIP in food analysis.

Benefits of MIP in food analysis have been discussed.Different functional monomers of MIPs have been discussed.Different cross-linkers of MIPs have been discussed.Theoretical interactions between functional monomers and templates for MIP design have been discussed.

Magnetic graphene oxide carbon dot nanocomposites as an efficient quantification tool against parabens in water and cosmetic samples.

A new method is developed for the simultaneous detection and extraction of parabens, including methyl paraben (MP), ethyl paraben (EP), propyl paraben (PP), and butyl paraben (BP), based on magnetic graphene oxide carbon dot nanocomposites (Fe3O4@GO@CD). Fe3O4@GO@CD has been synthesized using one pot hydrothermal method by intercalating iron oxide and carbon dots between the layers of graphene oxide. Fe3O4@GO@CD was applied as the magnetic solid phase sorbent for the simultaneous extraction and detection of parabens from water (tap and river water) and cosmetic samples (hair serum and sunscreen cream). MP was measured at concentration of 0.25-0.26 ng/mL in hair serum, while PP at 0.32-0.33 ng/mL in sunscreen cream. Notably, good recoveries (88.74-98.03%; RSD = 2.31-6.88%) for river and tap water with detection limit of 0.039-0.046 ng/mL were attained. The method has good cyclability up to 16 cycles and was highly repeatable. All these findings suggest that the Fe3O4@GO@CD would be potential sorbent for the analysis of parabens.

A Review of the Analysis of Phthalates by Gas Chromatography in Aqueous and Food Matrices.

As a commonly well-known industrial chemical, phthalates are produced in high volumes to be used in various consumer products (e.g., plasticizers, medical devices, construction materials, and toys) to enhance softness, durability, transparency, and flexibility. Phthalates are generally not chemically bonded to the polymer chain of the plastic in which they are mixed. Thus, they may leach, migrate, or evaporate into indoor/outdoor air, and foodstuffs. In this review, a comprehensive overview of several sample preparation methods coupled with gas chromatography for the analysis of phthalates in various kinds of complex matrices, with a focus on the last 20 years' worth of papers. The review begins by highlighting the environmental significance of phthalate pollution along with the various routes to their exposure to general population. Then, the discussion is extended to cover the pretreatment and extraction techniques for phthalates for their quantitation based on gas chromatographic approach. Finally, the present and future challenges for the detection of phthalates in aqueous and food matrices are discussed.

Fluorescence "Turn-off" Sensing of Iron (III) Ions Utilizing Pyrazoline Based Sensor: Experimental and Computational Study.

A simple pyrazoline-based ''turn off'' fluorescent sensor 5-(4-methoxyphenyl)-3-(5-methylfuran-2-yl)-1-phenyl-4,5-dihydro-1H-pyrazole (PFM) was synthesized and well characterized by different techniques such as FT-IR, 1H-NMR, 13C-NMR, and mass spectrometry. The synthesized sensor PFM was utilized for the detection of Fe3+ ions. Fluorescence emission selectively quenched by Fe3+ ions compared to other metal ions (Mn2+, Al3+, Fe2+, Hg2+, Cu2+, Co2+, Ni2+, Cd2+, Pb2+, and Zn2+) via paramagnetic fluorescence quenching and showed good anti-interference ability over the existence of other tested metals. Under optimum conditions, the fluorescence intensity of sensor quenched by Fe3+ in the range of 0 to 3 µM with detection limit of 0.12 µM. Binding of Fe3+ ions to PFM solution were studied by fluorescent titration, revealed formation of 1:1 PFM-Fe metal complex and binding constant of complex was found to be of 1.3 × 105 M-1. Further, the fluorescent sensor has been potentially used for the detection of Fe3+ in environmental samples (river water, tap water, and sewage waste water) with satisfactory recovery values of 99-101%.

Self-polymerized polydopamine-imprinted layer-coated carbon dots as a fluorescent sensor for selective and sensitive detection of 17ß-oestradiol.

The compound 17ß-oestradiol (E2) is a steroidal oestrogen used extensively in food processing and animal husbandry. As E2 is well-known as a typical endocrine disrupting chemical, its release, penetration, and exposure create serious environmental concerns. Carbon dots (CDs) have attracted great attention due to their excellent fluorescent and non-toxic properties. To help improve the selectivity of CDs, they can be combined with molecularly-imprinted polymers (MIPs). In light of the limitations involved in the fabrication of MIP layer on CDs (e.g., time consumption and low controllability of imprinted layer), the mussel inspired dopamine self-polymerization can be considered as an alternative option. As functional monomer in molecular imprinted technology, dopamine can be used efficiently to polymerize in weak alkaline condition (e.g., formation of polydopamine). In this research, a new method was developed for selective and sensitive fluorescent detection of E2 based on self-polymerization of dopamine (functional monomer) on fluorescent carbon dots (CDs@MI-PDA). The developed sensor selectively binds with E2 to quench the fluorescence intensity of CDs by photo-induced electron transfer. The sensor showcases a detection limit of E2 as 0.34 ng/mL with a linearity over 1-50 ng/mL. Furthermore, the probe was successfully applied to water (tap and river water) and milk samples with recoveries of 96.4-102.2 %. This study is expected to open a new path for the development of a simple and convenient detection approach for E2 present in complex matrices.

Mesoporous silica imprinted carbon dots for the selective fluorescent detection of triclosan.

A molecularly imprinted fluorescence sensor built as a mesoporous structured silica imprinted layer on the surface of carbon dots (CDs@m-MIP) was employed for the selective detection of triclosan (TRI). The fluorescence of this CDs@m-MIP was affected sensitively and selectively by TRI via an electron transfer-induced fluorescence quenching mechanism with a detection limit of TRI at 1.08 nM (range 1.72-138 nM) under the optimum setup (e.g., pH, response time, and CDs@m-MIP dose). This approach was used successfully to detect TRI in real water samples (e.g., sewage, river, and tap water). The recoveries of TRI were satisfactory in spiked river and tap water (in 94.7-99.5 %). The outcome of this research is thus expected to help develop highly efficient fluorescent sensing systems towards diverse hazardous compounds including TRI.

Experimental and Theoretical Studies of the Pyrazoline Derivative 5-(4-methylphenyl)-3-(5-methylfuran-2-yl)-1-phenyl-4,5-dihydro-1H-Pyrazole and its Application for Selective Detection of Cd2+ ion as Fluorescent Sensor.

A simple fluorescent chemosensor 5-(4-methylphenyl)-3-(5-methylfuran-2-yl)-1-phenyl-4, 5-dihydro-1H-pyrazole (PY) has been synthesized for the detection of Cd2+ ion.The fluorescent probe PY shows high selectivity for Cd2+in the presence of othermetal ions (Co2+, Cu2+, Hg2+, Mn2+, Zn2+, Fe3+, Pb2+, Ni2+, and Al3+). The fluorescence intensity of the PY has been strongly quenched with increasing concentration of Cd2+ (0-0.9 µM)via photoinduced electron transfer mechanism. The binding constant of Cd2+ to PY for the 1:1 complex isfound to be 5.3 × 105 M-1with a detection limit of 0.09 µM. The chemosensor was successfully applied for determination of Cd2+ in different water samples (tap, river, and bottled water) showing good recovery values in the range of 94.8-101.7% with RSD less than 3%. Density functional theory (DFT) calculations were also performed to investigate electronic and spectral characteristics which are quite agreeable with the experimental value. The results show that the synthesized fluorescent chemosensor shows good selectivity towards Cd2+ and can be readily applied for the detection of Cd2+ in real samples including water samples.

Bis(thiophen-2-yl-methylene) Benzene-1, 4-Diamine as Fluorescent Probe for the Detection of Fe3+ in Aqueous Samples.

A Schiff base bis(thiophen-2-yl-methylene)benzene-1, 4-diamine (L) was synthesized and used for selective and sensitive detection of Fe3+. L exhibited enhanced fluorescence response at excitation of 365 nm and emission wavelength of 440 nm for Fe3+. The formation of a 1:1 complex between L and Fe3+ was suggested by Job's plot by fluorescence titration and from optimized structures using Density functional theory (DFT). The fluorescence intensity was directly proportional to concentration of Fe3+ (R2 = 0.999) with the detection limit of 3.8 × 10-7 M and the binding constant of 1.20 × 104 M-1 at pH = 6.0. The probe was used to detect Fe3+ in different water samples with the percentage recovery of 99.7-103%. The interference of the other cations are < 5%.

Synchronous Fluorescence Determination of Al3+ Using 3-Hydroxy-2-(4-Methoxy Phenyl)-4H-Chromen-4-One as a Fluorescent Probe.

A simple synchronous fluorescent chemosensor 3-hydroxy-2-(4-methoxyphenyl)-4H-chromen-4-one (3-HC) has been synthesized for the selective analysis of Al3+. On the addition of Al3+, 3-HC displayed a redshift with a change in wavelength of emission maximum from 436 to 465 nm along with enhancement in fluorescence intensity, which formed the basis for its sensitive detection. Under optimized conditions, 3-HC was applied for the determination of Al3+ in the concentration range of 1 × 10-7-1 × 10-6 M. The limit of detection (LOD) and limit of quantification (LOQ) values were found out to be 1.69 × 10-8 and 5.07 × 10-8 M respectively. Further, the developed method was applied for the analysis of Al3+ in real water samples (tap water, bottled water, and tube well water) which showed good recovery values in the range of 95-99.7% with RSD less than 4%.

Hollow porous molecularly imprinted polymers as emerging adsorbents.

Hollow porous molecularly imprinted polymers (HPMIPs) are identified as promising adsorbents with many advantageous properties (e.g., large number of imprinted cavities, highly accessible binding sites, controllable pore structure, and fast mass transfer). Because of such properties, HPMIPs can exhibit improved binding capacity and kinetics to make analyte molecules readily interact with a greater number of recognition sites on the imprinted shell. This review highlights the synthesis and utility of HPMIPs as adsorbents to cover diverse targets of interest (e.g., endocrine disrupting chemicals, pharmaceuticals, pesticides, and heavy metal ions). The overall potential of HPMIPs is thus discussed in the context of analytical chemistry with particular focus on the efficient extraction of trace-level targets from complex matrices.

Dual-template magnetic molecularly imprinted polymer-based sorbent for simultaneous and selective detection of phenolic endocrine disrupting compounds in foodstuffs.

In this research, an efficient (94.9-99.4%) and fast (5 min) method has been developed and validated for simultaneous identification and quantification of phenolic endocrine disrupting compounds with an emphasis on bisphenol A (BPA) and 4-cumylphenol (4-CP) in food stuffs using a dual-template magnetic, molecularly-imprinted polymer (dt-MMIP). The dt-MMIP was synthesized by a sol-gel method using Fe3O4@SiO2 (as the core) and BPA and 4-CP (as templates). The dt-MMIP was coupled with magnetic solid phase extraction to simultaneously detect BPA and 4-CP in food samples. BPA was measured from bottled water and fruit juice samples samples at 0.36 and 0.24 ng mL-1, respectively, while 4-CP in those samples was 0.33 and 0.16 ng mL-1, respectively. Their detection limits were estimated as 0.04 and 0.05 ng mL-1, respectively. The developed dt-MMIP method was highly reproducible, while maintaining a good cyclability up to 20 cycles.

Surface Molecularly Imprinted Carbon Dots Based Core-Shell Material for Selective Fluorescence Sensing of Ketoprofen.

In this work, we report an environment friendly core-shell material based on Carbon Dot core and Molecularly Imprinted Polymer shell as sensor for highly selective fluorescence detection of ketoprofen. The Carbon Dots (CDs) were prepared by a hydrothermal method and the polymer layer around the CDs core was synthesised by sol-gel polymerisation. The prepared material was characterized by Fluorescence Spectroscopy, FT-IR Spectroscopy and Transmission Electron Spectroscopy (TEM). Fluorescence from the Carbon Dots- Molecularly Imprinted Polymer (CDs-MIP) was found to quench selectively in the presence of ketoprofen and quenching effect was found to be greater than for Non-Imprinted Polymer (CDs-NIP) which indicated the potential of CDs-MIP as a fluorescence sensing material for ketoprofen. The imprinting factor was obtained to be 2.35. Under optimized conditions, a linear response was obtained in the concentration range from 0.039 to 3.9 µM with a detection limit of 0.01 µM. The correlation coefficient was 0.999. The developed sensor was applied to determination of ketoprofen in human serum and urine samples with good recoveries ranging from 96 to 104% indicating successful application of the proposed sensor in biological fluids.