Recognition of human hemoglobin with macromolecularly imprinted polymeric nanoparticles using non-covalent interactions.

Hemoglobin (Hb) is the most abundant protein in the blood. It is vital for the living as oxygen carriers. Some of the very pure Hb-containing biological fluids are currently under clinical trial. However, the removal and purification of Hb from the blood are quite difficult, especially when it is at a low concentration level. In this study, the molecularly imprinted polymeric nanoparticles (MIPNs) were prepared using N-methacryloyl-histidine methyl ester (MAH) by mini-emulsion polymerization technique for specific binding of human hemoglobin (HHb). MIPNs in monosize form have a size of 152 ± 4 nm. They also have a high binding capacity (32.33 mg/g) of HHb. MIPNs retain 84% of the re-binding capacity for HHb after 10 cycles. The nanoparticles have 16 and 5 times higher binding capacity of HHb, respectively, in the presence of bovine serum albumin and lysozyme. Thanks to their high binding capacity and selectivity, MIPNs will allow them to be detected selectively for different target molecules. According to molecular docking, the main binding forces depend on hydrogen bonds and Van der Waals forces in the interaction within 5 Å around MAH molecule are observed through the amino acid residues of HHb at ß1 and ß2 subunit. The statistical mechanical analysis of docking showed that the free energy (ΔG) is -2732.14 kcal/mol, which indicates the interaction between MAH and HHb is energetically favorable at 298.15°K.

Development of a molecularly imprinted polymer on silanized graphene oxide for the detection of 17-estradiol in wastewater.

This research article demonstrates the synthesis, characterization, and electrochemical evaluation of a molecularly imprinted polymer (MIP) on the surface of silanized graphene oxide (silanized GO), which is nanostructured and used to quantify 17-estradiol (E2) in wastewater. As characterization methods, X-ray diffraction (XRD), Raman spectroscopy, dynamic scattering light (DSL), scanning electron microscope (SEM), and Fourier transform infrared spectroscopy (FTIR) were utilized to examine the synthesized GO, silanized GO, MIP-GO composite, and non-imprinted polymer (NIP)-GO (NIP-GO) composite. FTIR results confirmed the successful synthesis of GO composites. Raman study confirmed the synthesis of monolayer silanized GO, MIP-GO composite, and NIP-GO composite. Surface morphology revealed that after polymerization, the surface of silanized GO sheet-like morphology is covered with nanoparticles. Adsorption kinetics studies revealed that adsorption follows the pseudo-second-order kinetics. Further, we studied the performance of a MIP-GO-based sensor by optimizing the effects of pH, scan rate, and incubation period. The linear calibration was achieved between the oxidation peak current and E2 concentration from 0.1 to 0.81 ppm, with a detection limit of 0.037 ppm. The selectivity of the MIP-GO composite was also checked by using other estrogens, and it was found that E2 is 3.3, 0.5, and 1.4 times more selective than equilin, estriol, and estrone, respectively. The composite was successfully applied to the wastewater samples for the detection of E2, and a good percentage of recoveries were achieved. It suggests that the reported composite can be applied to real samples. PRACTITIONER POINTS: An innovative electrochemical sensor was developed for selective detection of 17-estradiol through molecularly imprinted polymer fabricated on the surface of silanized GO (MIP-GO composite). The developed method was comprehensively validated and found to be linear in the range of 0.1 to 0.8 ppm of 17-estradiol, with 0.037 ppm of limit of detection and 0.1 ppm of limit of quantification, respectively. The developed MIP-GO-composite-based electrochemical sensor was found 3.3, 0.5, and 1.4 times more selective for 17-estradiol than equiline, estriol, and estrone, respectively. The applicability of a developed sensor was also checked on wastewater samples, and a good percent recovery was obtained.

Molecularly Designed Ion-Imprinted Nanoparticles for Real-Time Sensing of Cu(II) Ions Using Quartz Crystal Microbalance.

A molecularly designed imprinting method was combined with a gravimetric nanosensor for the real-time detection Cu(II) ions in aqueous solutions without using expensive laboratory devices. Thus, 1:1 and 2:1 mol-ratio-dependent coordination modes between Cu(II), N-methacyloly-L histidine methyl ester (MAH) functional monomer complexes, and their four-fold and six-fold coordinations were calculated by means of density functional theory molecular modeling. Cu(II)-MIP1 and Cu(II)-MIP2 nanoparticles were synthesized in the size range of 80-100 nm and characterized by SEM, AFM and FTIR. Cu(II)-MIP nanoparticles were then conducted to a quartz crystal microbalance sensor for the real-time detection of Cu(II) ions in aqueous solutions. The effects of initial Cu(II) concentration, selectivity, and imprinting efficiency were investigated for the optimization of the nanosensor. Linearity of 99% was obtained in the Cu(II) ion linear concentration range of 0.15-1.57 µM with high sensitivity. The LOD was obtained as 40.7 nM for Cu(II)-MIP2 nanoparticles. The selectivity and the imprinting efficiency of the QCM nanosensor were obtained significantly in the presence of competitive ion samples (Co(II), Ni(II), Zn(II), and Fe(II)). The results are promising for sensing Cu(II) ions as environmental toxicants in water by combining molecularly designed ion-imprinted nanoparticles and a gravimetric sensor.

Study on Cost-Efficient Carbon Aerogel to Remove Antibiotics from Water Resources.

Because of pharmaceutical-emerging contaminants in water resources, there has been a significant increase in the antibiotic resistance in bacteria. Therefore, the removal of antibiotics from water resources is essential. Various antibiotics have been greatly studied using many different carbon-based materials including graphene-based hydrogels and aerogels. In this study, carbon aerogels (CAs) were synthesized from waste paper sources and their adsorption behaviors toward three antibiotics (hygromycin B, gentamicin, and vancomycin) were investigated, for which there exist a limited number of reports in the literature. The prepared CAs were characterized with scanning electron microscopy, transmission electron microscopy, X-ray photoelectron spectroscopy, and micro-computerized tomography (µ-CT). According to the µ-CT results, total porosity and open porosity were calculated as 90.80 and 90.76%, respectively. The surface area and surface-to-volume ratio were found as 795.15 mm2 and 16.79 mm-1, respectively. The specific surface area of the CAs was found as 104.2 m2/g. A detailed adsorption study was carried out based on different pH values, times, and analyte concentrations. The adsorption capacities were found as 104.16, 81.30, and 107.52 mg/g for Hyg B, Gen, and Van, respectively. For all three antibiotics, the adsorption behavior fits the Langmuir model. The kinetic studies showed that the system fits the pseudo-second-order kinetic model. The production of CAs, within the scope of this study, is safe, facile, and cost-efficient, which makes these green adsorbents a good candidate for the removal of antibiotics from water resources. This study represents the first antibiotic adsorption study based on CAs obtained from waste paper.

Selective binding of antibiotics using magnetic molecular imprint polymer (MMIP) networks prepared from vinyl-functionalized magnetic nanoparticles.

Adverse effects of pharmaceutical emerging contaminants (PECs), including antibiotics, in water supplies has been a global concern in recent years as they threaten fresh water security and lead to serious health problems to human, wildlife and the environment. However, detection of these contaminants in water sources, as well as food products, is difficult due to their low concentration. Here, we prepared a new family of magnetic molecular imprinted polymer (MMIP) networks for binding antibiotics via a microemulsion polymerization technique using vinyl silane modified Fe3O4 magnetic nanoparticles. The cross-linked polymer backbone successfully integrated with 20-30 nm magnetic nanoparticles and generated a novel porous polymeric network structure. These networks showed a high binding capacity for both templates, erythromycin and ciprofloxacin at 70 and 32 mg/g. Both MMIPs were also recyclable, retaining 75 % and 68 % of the binding capacity after 4 cycles. These MMIPs have showed a clear preference for binding the template molecules, with a binding capacity 4- to 7-fold higher than the other antibiotics in the same matrix. These results demonstrate our MMIP networks, which offered high binding capacity and selectivity as well as recyclability, can be used for both removal and monitoring hazardous antibiotic pollutants in different sources/samples and food products.