Selective Recognition Properties Research Articles

Two helical Schiff bases with “AIE+ESIPT” characteristics exhibiting selective ion recognition properties

Two racemic Schiff bases (H4L1 and H4L2) were synthesized and characterized, and the crystal structures indicated their helical configurations with equal amounts of P- and M-helicity. The aggregation-induced emission (AIE) and selective ion recognition properties of H4L1 and H4L2 were investigated using UV–vis absorption and fluorescence spectra. The results showed that both H4L1 and H4L2 exhibited obvious “AIE + ESIPT” characteristics in THF/H2O solution upon increasing the water fraction. Both H4L1 and H4L2 displayed an obvious turn-off fluorescence response to Cu2+ and F−, and a slight turn-off response to Fe3+ in DMSO, while they displayed an efficient selective ion recognition of Cu2+ in THF/H2O (1: 1, V/V). The corresponding stoichiometry ratio, association constant, Stern-Volmer quenching constant, and the detection limits were determined via Job's plots, UV–vis spectra titration as well as fluorescence spectra titration experiments. The crystal structures of the complexes obtained from the interactions of H4L1 with Cu2+ and Fe3+ illustrated their binding modes and binding differences, which helped us interpret the ion recognition mechanism of H4L1 and H4L2. In addition, the application of H4L2 on test strips was performed, indicating that H4L2 can be used for the rapid detection of Cu2+ and F− in THF. The acid-responsive fluorescence behavior of H4L2 showed that the white light emission can be obtained upon the addition of hydrochloric acid or aldehyde c into H4L2.

A highly selective and sensitive peptide-based probe for the colorimetric and fluorescent detection of Fe3+, Al3+ and Cr3+ and its application in living cells imaging

A new colorimetric and fluorescent dual-responsive probe named Rb-SSC was designed and synthesized using Rhodamine B and tripeptide (SerSerCys-NH2) as raw reactants. The selective recognition properties in detecting 17 metal ions were investigated by UV–Vis spectroscopy and fluorescence spectroscopy in DMF/water (4:6, v/v, 10.0 mM HEPES, pH = 7.4), and the results showed that Rb-SSC had high selectivity fluorescence response and clear colorimetric analysis for trivalent metal ions (Fe3+, Al3+ and Cr3+). These selectivity were attributed to protonation of Rb-SSC, and the Ksp value of the trivalent ions promotes the formation of hydrolyzed H+. Additionally, the limit of detections (LODs) were found to be 27.4 nM for Fe3+, 28 nM for Al3+ and 62.3 nM for Cr3+, respectively. In addition, MTT assay and cells experiments showed that Rb-SSC has low toxicity and achieved fluorescence imaging of trivalent metal ions in living cells. What's more, the G/B ratio has a good linear relationship with the concentrations of Fe3+ based on the smartphone sensing platform (RGB values), and the limit of detection (LOD) was as low as 0.37 μM.

Hybrid chain reaction and selective recognition-based homogeneous dual-fluorescence analysis of circulating tumor cells in clinical ovarian cancer samples

BackgroundOncological analysis is important in tumor diagnosis. We constructed a dual-fluorescence and binary visual analysis system for circulating tumor cells (CTCs) using the folate receptor as a biomarker, combined with hybridization chain reaction and nanomaterial amplification. This strategy integrates terminal protection, selective recognition properties of N-methyl mesoporphyrin IX and CdTe quantum dots for Cu2+ and double-stranded templated copper nanoparticles, and inkjet printing technology. ResultsIn fluorescence mode, folate receptor and A2780 ovarian cancer cells were specifically detected with a limit of detection of 0.1 fg mL−1, and 10 cells mL−1 were observed. The detection limits of both the color and distance reading modes were comparable to those obtained in fluorescence mode. The applicability of the method for quantifying CTCs was validated using 27 (6 negative and 21 positive) clinical ovarian cancer samples; the results agreed with those of both the clinical folate receptor-polymerase chain reaction kit and radiological and pathological results. SignificanceThis dual-fluorescence and binary visual CTCs detection method provides multiple options for clinical tumor liquid biopsy.

A tetraphenylethylene-based acylhydrazone Schiff base macrocycle exhibiting aggregation-induced emission and “turn-on” detection of Al3+ ions

A tetraphenylethylene-based acylhydrazone macrocycle (H8L) was designed and synthesized via Schiff base condensation reaction. The [2 + 2] molecular structure of H8L was determined via 1H NMR, 13C NMR, elemental analysis, ESI-MS, and single crystal X-ray diffraction. The “ESIPT + AIE” and selective recognition properties of macrocycle H8L were investigated via UV–vis absorption spectra and fluorescence emission spectra. The results showed that macrocycle H8L exhibited an obvious AIE characteristic in THF/H2O solution with varying water fraction, and displayed a selective “turn-on” response to Al3+ ions in the solution of THF/H2O (V: V = 4: 1). In addition, the visualization of latent fingerprints and the application of H8L on test strips were performed as well.

A Molecularly Imprinted Polymer Based on Fe3O4@Au Nanoparticles for Detection of Aflatoxin B1 in Food Samples

AbstractBased on molecular imprinting and nanotechnology, a molecular imprinted polymer (MIP) coupled with Fe3O4−Au nanocomposite adsorbent has been successfully developed for rapid quantification of aflatoxin B1 in foodstuff. The characterization of the prepared Fe3O4−Au and Fe3O4−Au‐MIP was studied by scanning electron microscopy (SEM), energy dispersive X‐ray spectroscopy (EDX), transmission electron microscopy (TEM), Fourier‐transform infrared spectroscopy (FTIR), X‐ray diffraction (XRD), and vibrating sample magnetometer (VSM). The limit of detection (LOD) and limit of quantification (LOQ) were estimated to be 6.12 and 18.6 μg L−1, respectively. The adsorption capacity was 8.975 mg g−1 which revealed that the synthesized magnetic MIP (MMIP) presented high selective recognition property to AFB1. The selectivity adsorption experiments indicated that compared with three different competetive Aflatoxins, MMIP showed excellent affinity to AFB1. It was found that the adsorption capacity of MMIP for AFB1 remained essentially the same after 6 adsorption‐desorption cycle which shows the acceptable repeatability and reusability of the MMIP. The proposed method was successfully applied to the estimation of AFB1 in non‐alcoholic beer and barley samples with good recoveries (94.47–97.31 %). Also, the relative standard deviation (RSD %) values were lower than 3.7 %. The selectivity, stability and reproducibility of the proposed method were acceptable. The results revealed that Fe3O4−Au@MIP could be used as an efficient and reusable adsorbent for AFB1 in food samples. This study provides a simple, inexpensive, fast, accurate and environmentally‐friendly technique instead of expensive and time‐consuming procedures for determining AFB1 in food matrices.

Rapid Screening and Synthesis of Abiotic Synthetic Receptors for Selective Bacterial Recognition

The major challenges that impede the preparation of abiotic synthetic receptors designed to feature selective bacterial recognition properties are the complexity, nonrobustness, and environmental adaptability of live microbes. Here, we describe a new rapid screening strategy to determine the optimal polymer formulation on 96-well plates and then produce abiotic synthetic receptors by imprinting the surface marker lipopolysaccharide (LPS) of Gram-negative bacteria. The resulting LPS-imprinted nanoparticles reveal remarkable affinity toward LPS with an equilibrium dissociation constant (KD) value of 10-12 M and can distinguish and selectively recognize specific bacteria in whole blood at concentrations down to 10 cells/mL. The incorporation of gold nanorods into imprinted nanoparticles allows selective microbial inactivation based on photothermal treatment. We have also demonstrated that the imprinted nanoparticles with high affinity for bacteria could induce bacteria clustering, drive the expression of quorum-sensing-controlled signal molecules, and eventually enhance the productivity of the cell factory.

Multiple signal amplification and selective recognition reactions-assisted homogeneous binary visual aptasensor of tuberculosis interferon γ in clinical samples

Interferon-γ (IFN-γ) analysis is critical for tuberculosis (TB) diagnosis. However, the existing conventional immunoassay methods are less sensitive and laborious. We describe cadmium telluride quantum dots (CdTe QDs) and calcein-based binary visual and fluorescence homogeneous aptamer sensing strategy for IFN-γ analysis. This strategy integrates enzyme-free catalytic hairpin assembly (CHA) amplification, selective recognition properties of QDs and calcein for Ag+ and C-Ag+-C structures, and ink-jet printing technology for making test strips. Using QDs- and calcein-based fluorescence modes, respectively, IFN-γ with limits of detection (LODs) as low as 0.3 ag/mL and 0.25 ag/mL were obtained at optimum conditions. Color and distance reading modes enabled the analysis of 100 ag/mL IFN-γ with naked eyes. Quantitative findings of IFN-γ analysis in 51 clinical plasma samples using dual fluorescence modes were in line with those obtained by enzyme-linked immunosorbent assay (ELISA), sputum culture, polymerase chain reaction (PCR), Xpert MTB/rifampin (RIF) and computed tomography (CT). Additionally, findings from IFN-γ analysis in 12 clinical samples obtained using QDs- and calcein-based distance reading strips were highly consistent with those of ELISA. Therefore, our analytical system may provide an additional and more sensitive tool for early diagnosis of TB.

Dispersive solid phase extraction of ginkgolide B from real samples using 3D reduced oxide graphene aerogel based molecularly imprinted polymers

AbstractIn this article, novel molecularly imprinted polymers based on 3D reduced graphene oxide aerogel (3D RGO‐GBMIPs) were successfully fabricated and applied as adsorbents for dispersed solid‐phase extraction (DSPE) of ginkgolide B (GB). After being prepared by surface molecular imprinted technology, 3D RGO‐GBMIPs were successively characterized by fourier transform infrared spectroscopy, thermogravimetric analysis, Raman spectroscopy, and scanning electron microscope. The results of adsorption experiments revealed that 3D RGO‐GBMIPs presented highly selective recognition properties and well reusability. The main variables influencing DSPE efficiency, including extraction solvent, 3D RGO‐GBMIPs dosage, category, and volume of eluent, as well as elution time were investigated. The DSPE results showed that 3D RGO‐GBMIPs had an obvious effect on the improvement of GB purity in ginkgo biloba extract, with a satisfactory recovery rate and yield. Therefore, 3D RGO‐GBMIPs are expected to be applied for the enrichment of GB from complex matrices.

Insights into a new alternative method with graphene oxide/polyacrylamide/Fe3O4 nanocomposite for the extraction of six odor-active esters from Strong-aroma types of Baijiu.

Liquid-liquid extraction (LLE) is the most commonly utilized technique for the extraction of odor-active esters (OAEs) in strong-aroma types of Baijiu (SAB). However, since the contents of different OAEs in SAB vary widely, it is still a puzzle to ensure that all OAEs to be thoroughly extracted by LLE without the problem of saturated adsorption. Herein, a novel approach of magnetic solid phase extraction (MSPE), based on the magnetic graphene oxide nanocomposite modified with polyacrylamide (GO/PAM/Fe3O4), was employed for the efficient extraction of six OAEs from SAB. Compared with LLE, GO/PAM/Fe3O4 exhibited highly selective recognition properties and larger adsorption capacities for OAEs (ranging from 13.68 to 39.06mg/g), resulting in better extraction performances for OAEs. Coupled with GC-MS, six OAEs in real SAB were successfully determined, with recoveries ranged from 70.1∼90.0% and LODs at 0.08∼1.35µg/L. Overall, the MSPE-GC/MS is a promising alternative for accurate determination of OAEs in SAB.

Anion Exchange Affinity-Based Controllable Surface Imprinting Synthesis of Ultrathin Imprinted Films for Protein Recognition.

Anion exchange affinity-based controllable surface imprinting is an effective approach to overcome low imprinting efficiency and high non-specific binding capacity. The template proteins were first immobilized on the anchored tetraalkylammonium groups of the nanoparticles via anion exchange affinity-based interactions, enabling monolayer sorption using a low template concentration. The combined use of surface-initiated photoiniferter-mediated polymerization to precisely control the imprinted film thickness, allowing the formation of homogeneous binding cavities, and the construction of effective binding sites resulted in a low non-specific binding capacity and high imprinting efficiency. The obtained imprinted films benefited from the anion exchange mechanism, exhibiting a higher imprinting factor and faster binding rate than the reference material. Binding tests revealed that the binding strength and selective recognition properties could be tuned to a certain extent by adjusting the NaCl concentration. Additionally, in contrast to the harsh template elution conditions of the covalent immobilization approach, over 80% of the template molecules were readily removed from the imprinted films using supersonic elution with an aqueous mixture of NaCl and HAc. Introducing template immobilization by anion exchange interactions to the synthesis of imprinted materials may provide a new approach for effective biomacromolecular imprinting.

Catalytic Clusterbody for Enhanced Quantitative Protein Immunoblot.

To assess low-abundance protein biomarkers associated with tumor progression, we have developed artificial catalytic antibodies based on well-defined metal clusters modified with rationally designed peptides, termed clusterbodies. Such clusterbodies possess favorable integrated features of matched ultrasmall sizes, intrinsic fluorescence, and enzyme-like catalytic and selective recognition properties that are inaccessible to traditional antibodies. Consequently, a quantitative assay with high accuracy and high sensitivity is established by measuring the fluorescence and catalytic chemiluminescence of metal clusters preferentially recognizing the protein biomarker, which is confirmed by the molecular-weight marker references of immunoblotting. The results of quantitative immunoblotting are highly close to that derived from the enzyme-linked immunosorbent assay, implying the reliability of this protocol. Remarkably, the detection limit of the aimed protein achieved is as low as 1.0 pg, one magnitude lower than that of the conventional immunoassay. The significant variation of expression levels of the biomarker in tumor cells evidently indicates their distinguished invasion ability. This platform has potential application in analyzing low-abundance protein biomarkers in complex biological matrixes, which is essential to corroborate tumor malignancy in early stage. It inspires the construction of clusterbody-based precise bioprobes with customized structures and integrative functions for advanced quantitative biosensing.

Magnetic borate-modified Mxene: A highly affinity material for the extraction of catecholamines

A novel magnetic borate-modified MXene composite was prepared by in situ growth of Fe3O4 particles onto the surface of phenylboronic acid modified Ti3C2Tx nanosheets. The magnetic composite possesses highly selective recognition properties to catecholamines, and high adsorption capacity (up to 319.6 μmol g−1) for dopamine. Besides, the adsorption of urinary catecholamines can be accomplished within 2.0 min. The excellent adsorption performance can be assigned to its unique 2D layered structures, which helps to shorten the diffusion path and facilitate molecular transport. In addition, the multilayer adsorption and the synergetic interactions of borate affinity, van der Waals forces, hydrogen bonding and π-π stacking also contribute to the adsorption. By coupling the magnetic boronate affinity composites with high-performance liquid chromatography-fluorescence detection, a sensitive method for the determination of catecholamines in urine samples was proposed. The validation results revealed it can offer good linearities (correlation coefficients higher than 99%). The method detection limits were 0.06, 0.16, 0.03 and 0.14 ng mL−1 for norepinephrine, epinephrine, dopamine and isoprenaline, respectively, and relative recoveries for these catecholamines were in the range of 98.56–108.1%, 92.56–110.0%, 98.79–112.3% and 88.14–97.81%, respectively. The proposed method was successfully applied to analyze the catecholamines in the urine samples from 15 healthy volunteers and 16 patients with Alzheimer's disease. The results indicated that the magnetic borate-modified Mxene composite possesses superior extraction performance, and can be used as an outstanding candidate for the extraction of catecholamines in pre-clinical or clinical studies.

Aptamer-Functionalized Hybrid Nanostructures for Sensing, Drug Delivery, Catalysis and Mechanical Applications.

Sequence-specific nucleic acids exhibiting selective recognition properties towards low-molecular-weight substrates and macromolecules (aptamers) find growing interest as functional biopolymers for analysis, medical applications such as imaging, drug delivery and even therapeutic agents, nanotechnology, material science and more. The present perspective article introduces a glossary of examples for diverse applications of aptamers mainly originated from our laboratory. These include the introduction of aptamer-functionalized nanomaterials such as graphene oxide, Ag nanoclusters and semiconductor quantum dots as functional hybrid nanomaterials for optical sensing of target analytes. The use of aptamer-functionalized DNA tetrahedra nanostructures for multiplex analysis and aptamer-loaded metal-organic framework nanoparticles acting as sense-and-treat are introduced. Aptamer-functionalized nano and microcarriers are presented as stimuli-responsive hybrid drug carriers for controlled and targeted drug release, including aptamer-functionalized SiO2 nanoparticles, carbon dots, metal-organic frameworks and microcapsules. A further application of aptamers involves the conjugation of aptamers to catalytic units as a means to mimic enzyme functions “nucleoapzymes”. In addition, the formation and dissociation of aptamer-ligand complexes are applied to develop mechanical molecular devices and to switch nanostructures such as origami scaffolds. Finally, the article discusses future challenges in applying aptamers in material science, nanotechnology and catalysis.

Selective extraction of perfluorooctane sulfonate in real samples by superparamagnetic nanospheres coated with a polydopamine-based molecularly imprinted polymer.

Superparamagnetic core-shell structured molecularly imprinted polydopamine nanospheres were constructed via self-polymerization of dopamine to attach the template onto the surface of magnetic Fe3 O4 substrate in tris-HCl solution. Then they were used for the specific recognition and extraction of perfluorooctane sulfonate from environmental water and human serum samples. The structural features and morphological characterization of the magnetic imprinting nanospheres were assessed, indicating that the magnetic polydopamine imprinted composite was successfully prepared and featured excellent magnetic separation characteristics. Adsorption experiments revealed that the magnetic adsorbents exhibited rapid adsorption kinetics and highly selective recognition properties toward perfluorooctane sulfonate. The stability and regeneration experiments indicated the materials had repeatable activity retention after repeated reuse. As a magnetic solid-phase extraction adsorbent, it was successfully applied for the extraction and quantification of perfluorooctane sulfonate in environmental water and human serum samples combined with liquid chromatography tandem mass spectrometry, with recoveries of ∼70-101.5% obtained in real samples. These results demonstrate that the prepared magnetic imprinting nanospheres are effective for the selective separation of perfluorooctane sulfonate from real samples. The synthesis technique is an effective and facile method that is conducted in aqueous solution and at ambient temperature, which is low cost, environmentally benign, and easy for scaling-up.

Microfluidic Sensors Based on Molecularly Imprinted Polymers for Theselective Detection of Volatile Organic Compounds

Selective and sensitive detection of volatile organic compounds (VOCs) is of great importance in applications involving the monitoring of hazardous chemicals or non-invasive diagnosis. Diffusion-base microfluidic gas sensors are a new generation of gas detectors. These sensors have increased selectivity; this is primarily due to the effect of diffusion and adsorption/desorption (highly influenced by the coating materials and dimensions of the microfluidic channel) of the analyte molecules along the microfluidic channel (1,2). Therefore, the combination of the diffusion and adsorption/desorption rates of different analytes with different concentrations leads to a unique response (i.e., “smell print”) from the embedded sensor (3). In addition to the coating (or the combination of the layers coated) the surface roughness can affect adsorption and desorption phenomena and hence the performance (mainly selectivity) of the sensors. There are several ways to change the coating and roughness of the channel. One interesting method, which changes the surface material of the microchannel and interaction with the analyte, is the integration of molecularly imprinted polymer nanoparticles (MIP NPs) into the channel.MIP is a synthetic polymer possessing selective molecular recognition properties (due to its binding sites) with size, shape and functionalities complementary to the target molecules. MIPs, often called artificial antibodies or receptors, are alternatives to antibodies in a variety of applications. The advantages of MIPs over natural antibodies include easy and low-cost preparation, longer life cycles (up to several years), highly tailorable recognition properties, solvents and thermal stability, robustness and resistance to a wide range of pH, and ease of regeneration and sterilization.For the first time, MIP NPs were synthesized with acetone recognition sites due to its importance as a biomarker for the non-invasive diagnosis of several diseases like diabetes. The synthesized MIP NPs were integrated into a 3D-printed dual-channel platform (one channel without and the other with MIP NPs) to develop a highly selective detection device against various VOCs (alcohols, ketones, nitrile, and aromatic compounds).The MIP NPs with acetone recognition sites were prepared for the first time using the simple precipitation procedure. After polymerization, the solution was centrifuged and the final polymer was ground into a powder. To remove the template, the MIP powder was washed with acetonitrile, followed by heating the powder at 80ºC for 48 h. The morphology and chemical structure of MIP NPs were investigated by field emission scanning electron microscope and Fourier-transform infrared spectroscopy.The microfluidic-based gas platform consists of two microfluidic channels and gas sensors (embedded at the channel terminus). The microchannels were fabricated from VeroClear RGD810 using a 3D-printer . Each microchannel has equal dimensions of 500 µm in height, 3 mm in width, and 3 cm in length. The inner surfaces of the microchannels are coated with Parylene C using a chemical vapor deposition (CVD) coating machine . To investigate the effect of treating the channel with MIP NPs on the selectivity of the sensors, one channel was coated with MIP NPs (referred to as the MIP channel) and another one was left uncoated (referred to as the control channel). For this purpose, a certain amount of synthesized MIP NPs dispersed in acetonitrile was drop-casted on the surface of the MIP channel and dried for a day in a clean air chamber. VOCs flow into the channel inlet, diffuse along the microfluidic channel and reach gas detectors placed at the end of the microchannels when exposed to the device.The synthesized MIP NPs were integrated into a 3D-printed dual-channel platform (one channel without and the other with MIP NPs) to develop a highly selective detection device against various VOCs (alcohols, ketones, nitrile, and aromatic compounds). A simple feature extraction method was used to distinguish signals arising from different VOCs. The differences between the feature extraction of the two channels showed that in general, this platform was specific to acetone, proving the potential application of the MIP NPs in artificial olfaction platforms.Fig. 1 shows the response of the dual-channel detector when exposed to 200, 400, 800, 2000, 4000 ppm concentrations of several VOCs. The responses of both detectors increase with increasing concentrations of the target VOC. Although the response of the two detectors to the same target analyte was significantly different, with the increase in the concentration the magnitude of signals increases; however, the time of the maximum response still remains the same. It was also observed that for the low concentration of acetone, butanone and ethanol, the responses from the nonoMIP-coated detector are not distinguishable. This again confirms the interaction between these analytes and the MIP NPs.

Synthesis of antipyrine based organic material for Zn2+ ion sensing and implication in logic gate analysis

The antipyrine linked E allylic ester (BH-AP) ONO tridentate was synthesized, using acetate of Baylis-Hillman Adduct (BH) and antipyrine (AP) through SN2′ allylic substitution reaction.The newly synthesized ligand was characterized using IR and NMR spectroscopy.The ligand BH-AP was analyzed using UV–Visible and fluorescence techniques for its selective metal ion recognition properties. The emission spectroscopy exhibited the sensitivity and selectivity of the sensor for Zn2+ ion by significantly quenching the fluorescence intensity upon excitation at 268 nm. The 1:1 ratio binding stoichiometry and the binding constant value of 4.5796 × 10−6 M−1 were obtained for the ligand BH-AP with Zn2+ion. The appropriate combination of materials-AP, Zn2+and pH found to be suitable for NOR logic gate application.

(Invited) Microfluidic Sensors based on Molecularly Imprinted Polymers for the Selective Detection of Volatile Organic Compounds

Introduction Selective and sensitive detection of volatile organic compounds (VOCs) is of great importance in applications involving monitoring of hazardous chemicals or non-invasive diagnosis. Diffusion-base microfluidic gas sensors are a new generation of gas detectors. These sensors have increased selectivity; this is primarily due to the effect of diffusion and adsorption/desorption (highly influenced by the coating materials and dimensions of the microfluidic channel) of the analyte molecules along the microfluidic channel (1,2). Therefore, the combination of the diffusion and adsorption/desorption rates of different analytes with different concentrations leads to a unique response (i.e., “smell print”) from the embedded sensor (3). In addition to the coating (or the combination of the layers coated) the surface roughness can affect adsorption and desorption phenomena and hence the performance (mainly selectivity) of the sensors. There are several ways to change the coating and roughness of the channel. One interesting method, which changes the surface material of the microchannel and interaction with the analyte, is the integration of molecularly imprinted polymer nanoparticles (MIP NPs) in to the channel.Column CoatingMIP is a synthetic polymer possessing selective molecular recognition properties (due to its binding sites) with size, shape and functionalities complementary to the target molecules. MIPs, often called artificial antibodies or receptors, are alternatives to antibodies in a variety of applications. The advantages of MIPs over natural antibodies include easy and low-cost preparation, longer life cycles (up to several years), highly tailorable recognition properties, solvents and thermal stability, robustness and resistance to a wide range of pH, and ease of regeneration and sterilization.For the first time, MIP NPs were synthesized with acetone recognition sites due to its importance as a biomarker for the non-invasive diagnosis of several diseases like diabetes. The synthesized MIP NPs were integrated into a 3D-printed dual-channel platform (one channel without and the other with MIP NPs) to develop a highly selective detection device against various VOCs (alcohols, ketones, nitrile, and aromatic compounds). Method The MIP NPs with acetone recognition sites were prepared for the first time using the simple precipitation procedure. After polymerization, the solution was centrifuged and the final polymer was ground into a powder. To remove the template, the MIP powder was washed with acetonitrile, followed by heating the powder at 80ºC for 48 h. The morphology and chemical structure of MIP NPs were investigated by field emission scanning electron microscope (FE-SEM, FEI-Nova NanoSEM 450) and Fourier-transform infrared spectroscopy (FTIR, Shimadzu FTIR Prestige 21).The microfluidic-based gas platform consists of two microfluidic channels and gas sensors (embedded at the channel terminus). The microchannels were fabricated from VeroClear RGD810 using a 3D-printer (Connex 500). Each microchannel has equal dimensions of 500 µm in height, 3 mm in width, and 3 cm in length. The inner surfaces of the microchannels are coated with Parylene C using a chemical vapor deposition (CVD) coating machine (SCS PDS 2010 Labcoater). To investigate the effect of treating the channel with MIP NPs on the selectivity of the sensors, one channel was coated with MIP NPs (referred to as the MIP channel) and another one was left uncoated (referred to as the control channel). For this purpose, a certain amount of synthesized MIP NPs dispersed in acetonitrile was drop-casted on the surface of the MIP channel and dried for a day in a clean air chamber. VOCs flow into the channel inlet, diffuse along the microfluidic channel, and reach gas detectors placed at the end of the microchannels, when exposed to the device.The synthesized MIP NPs were integrated into a 3D-printed dual-channel platform (one channel without and the other with MIP NPs) to develop a highly selective detection device against various VOCs (alcohols, ketones, nitrile, and aromatic compounds). A simple feature extraction method was used to distinguish signals arising from different VOCs. The differences between the feature extraction of the two channels showed that in general this platform was specific to acetone, proving the potential application of the MIP NPs in artificial olfaction platforms. Results and Conclusions Fig. 1 shows the response of the dual-channel detector when exposed to 200, 400, 800, 2000, 4000 ppm concentrations of several VOCs. The responses of both detectors increase with increasing concentrations of the target VOC. Although the response of the two detectors to the same target analyte was significantly different, with the increase in the concentration the magnitude of signals increases; however, the time of the maximum response still remains the same. It was also observed that for the low concentration of acetone, butanone and ethanol, the responses from the nano MIP-coated detector are not distinguishable. This again confirms the interaction between these analytes and the MIP NPs.

ANÁLISIS DE CONTAMINANTES AMBIENTALES CON POLÍMEROS DE IMPRONTA MOLECULAR

Environmental pollutants affect negatively the environment, deteriorating the planet. The analysis of complex mixtures frequently requires several pretreatment steps and if the substance to be analyzed is present in low concentration, it needs to be concentrated so that it can be detected by standard analytical techniques. If it is a complex sample of similar compounds, a step is necessary that involves their cleaning. Solid-phase extraction is a widely used technique for sample pretreatment, since it is flexible and easy to automate. Molecularly imprinted polymers possess selective molecular recognition properties because the recognition sites within the polymer matrix are complementary to the molecule under analysis in the form and position of the functional groups. The molecular imprinting technique is based on the preparation of a highly cross-linked polymer around an analyte used as a template molecule, which is initially contacted with a suitable monomer in order to form a pre-polymerization complex and subsequently adds the cross-linker, the initiator and the solvent with which the polymerization is carried out. Once the polymer is obtained, the template molecule is extracted releasing the specific recognition sites. This paper presents a review of the molecular printing process and its applications in combination with solid phase extraction, to be used as an alternative for the pre-concentration of samples of environmental contaminants.

Molecularly Imprinted Polymers (MIPs) as Theranostic Systems for Sunitinib Controlled Release and Self-Monitoring in Cancer Therapy.

Cytotoxic agents that are used conventionally in cancer therapy present limitations that affect their efficacy and safety profile, leading to serious adverse effects. In the aim to overcome these drawbacks, different approaches have been investigated and, among them, theranostics is attracting interest. This new field of medicine combines diagnosis with targeted therapy; therefore, the aim of this study was the preparation and characterization of Molecularly Imprinted Polymers (MIPs) selective for the anticancer drug Sunitinib (SUT) for the development of a novel theranostic system that is able to integrate the drug controlled release ability of MIPs with Rhodamine 6G as a fluorescent marker. MIPs were synthesized by precipitation polymerization and then functionalized with Rhodamine 6G by radical grafting. The obtained polymeric particles were characterized in terms of particles size and distribution, ξ-potential and fluorescent, and hydrophilic properties. Moreover, adsorption isotherms and kinetics and in vitro release properties were also investigated. The obtained binding data confirmed the selective recognition properties of MIP, revealing that SUT adsorption better fitted the Langmuir model, while the adsorption process followed the pseudo-first order kinetic model. Finally, the in vitro release studies highlighted the SUT controlled release behavior of MIP, which was well fitted with the Ritger-Peppas kinetic model. Therefore, the synthesized fluorescent MIP represents a promising material for the development of a theranostic platform for Sunitinib controlled release and self-monitoring in cancer therapy.

Magnetic molecularly imprinted multishell particles for zearalenone recognition

This paper deal with the synthesis and characterization of a new class of magnetic molecularly imprinted (MIP) particles, with selective recognition properties for Zearalenone (ZEN), an estrogenic mycotoxin. These particles present a multishell structure, comprising a magnetic core, constituted by spherical aggregates of magnetite nanoparticles (Fe3O4 nanoparticles), covered by a thin silica layer and surrounded by a molecularly imprinted (MIP) polymer shell, obtained employing quercetin as the dummy template and 4-vinylpyridine as the functional monomer. A multistep synthetic procedure was developed leading to spherical particles with a mean diameter of approximately 900 nm and a high magnetic fraction. The MIP were tested for ZEN re-binding properties. ZEN-MIP material had 55-fold more affinity for ZEN than the corresponding non-imprinted (NIP) material, that highlighting their potential for ZEN concentration from complex food matrices.