Core-shell structured magnetic mesoporous carbon nanospheres derived from metal-polyphenol coordination polymer-coated Fe3 O4 and its application in the enrichment of phthalates from water samples

Synthesis of Phenylboronic Acid-Functionalized Magnetic Nanoparticles for Sensitive Soil Enzyme Assays

Soil enzymes, such as invertase, urease, acidic phosphatase and catalase, play critical roles in soil biochemical reactions and are involved in soil fertility. However, it remains a great challenge to efficiently concentrate soil enzymes and sensitively assess enzyme activity. In this study, we synthesized phenylboronic acid-functionalized magnetic nanoparticles to rapidly capture soil enzymes for sensitive soil enzyme assays. The iron oxide magnetic nanoparticles (MNPs) were firstly prepared by the co-precipitation method and then functionalized by (3-aminopropyl)triethoxysilane, polyethyleneimine and phenylboric acid in turn, obtaining the final nanoparticles (MNPPBA). Protein-capturing assays showed that the functionalized MNPs had a much higher protein-capturing capacity than the naked MNPs (56% versus 6%). Moreover, MNPPBA almost thoroughly captured the tested enzymes, i.e., urease, invertase, and alkaline phosphatase, from enzyme solutions. Based on MNPPBA, a soil enzyme assay method was developed by integration of enzyme capture, magnetic separation and trace enzyme analysis. The method was successfully applied in determining trace enzyme activity in rhizosphere soil. This study provides a strategy to sensitively determine soil enzyme activity for mechanistic investigation of soil fertility and plant–microbiome interaction.

An optosensor based on a hybrid sensing probe of mesoporous carbon and quantum dots embedded in imprinted polymer for ultrasensitive detection of thiamphenicol in milk

A hybrid fluorescent sensing probe was developed and used to quantitatively analyse thiamphenicol. The probe was constructed by entrapping mesoporous carbon and CdTe*CdS*ZnS quantum dots in molecularly imprinted polymer. The probe was characterized, and the construction and detection conditions were optimized. In the optimized conditions, the recognition sites of the nanoprobe were ultrasensitive and highly selective toward thiamphenicol. The quantitative analysis of thiamphenicol was based on the fluorescence quenching of the hybrid nanoprobe by thiamphenicol. Fluorescence emission was quenched linearly from 0.10 to 100 μg L^-1 with a coefficient of determination (R²) of 0.9979. The limit of detection was 0.04 μg L^-1. The accuracy of an optosensor based on the hybrid probe was evaluated by analyzing spiked milk samples. The results obtained were compared with the results of high-performance liquid chromatography (HPLC) analysis. The quantitative analysis of the spiked samples with the optosensor agreed well with HPLC analysis. Recoveries were in the range of 93.5 to 100.1 % with good precision (RSD < 5%). The accuracy, speed and convenience of the developed optosensor make it a powerful tool for the detection of thiamphenicol in milk.

Vortex-assisted Dispersive Solid-phase Extraction Using Schiff-base Ligand Anchored Nanomagnetic Iron Oxide for Preconcentration of Phthalate Esters and Determination by Gas Chromatography and Flame Ionization Detector

Phthalate esters are synthetic chemicals that are widely used in plastic industries as plasticizer. They are harmful to humans and could be carcinogenic. In this research, a new nanosorbent was prepared via a Schiff-base reaction between p-dimethylaminobenzaldehyde and Fe₃O₄@SiO₂-NH₂ nanoparticles. A characterization of the sorbent was performed by Fourier-transform infrared spectroscopy, transmission electron microscopy, scanning electron microscopy, and energy-dispersive spectroscopy. A modified nanosorbent has a core shell structure, and shows a great tendency towards the sorption of phthalate esters. Hence, it was utilized for the dispersive solid-phase extraction of six phthalate esters and determination by gas chromatography-flame ionization detection. Several variables, such as the pH, sorbent amount, salt effects, extraction and desorption time, extraction solvent type and volume, were investigated to establish the optimal conditions. Calibration graphs were linear in the range of 1.0 - 150.0 μg L^-1 for dimethyl phthalate, bis-(2-ethylhexyl) phthalate, di-n-octyl phthalate and 0.1 - 200.0 μg L^-1 for diethyl phthalate, di-n-butyl phthalate and butyl benzyl phthalate, respectively. The obtained limits of detections (S/N = 3) were in the range of 0.02 - 0.31 μg L^-1. Application of the method for the enrichment and determination of phthalate esters in mineral water, natural low fat yogurt and sodium chloride infusion (0.9%, w/v) was investigated.

Comprehensive Insight from Phthalates Occurrence: From Health Outcomes to Emerging Analytical Approaches

Phthalates are a group of chemicals used in a multitude of important industrial products (e.g., medical devices, children's toys, and food packages), mainly as plasticizers to improve mechanical properties such as flexibility, transparency, durability, and longevity of polyvinyl chloride (PVC). The wide occurrence of phthalates in many consumer products, including foods (e.g., bottled water, soft drinks, wine, milk, and meat) brings that most people are exposed to phthalates every day, which raises some concerns. Adverse health outcomes from phthalates exposure have been associated with endocrine disruption, deformities in the human reproductive system, increased risk of preterm birth, carcinogen exposure, among others. Apprehension related to the health risks and ubiquitous incidence of phthalates in foods inspires the development of reliable analytical approaches that allow their detection and quantification at trace levels. The purpose of the current review is to provide information related to the presence of phthalates in the food chain, highlighting the health risks associated with their exposure. Moreover, an overview of emerging extraction procedures and high-resolution analytical approaches for a comprehensive quantification of phthalates is presented.

Iron Oxide Mesoporous Magnetic Nanostructures with High Surface Area for Enhanced and Selective Drug Delivery to Metastatic Cancer Cells

This work reports the fabrication of iron oxide mesoporous magnetic nanostructures (IO-MMNs) via the nano-replication method using acid-prepared mesoporous spheres (APMS) as the rigid silica host and iron (III) nitrate as the iron precursor. The obtained nanosized mesostructures were fully characterized by SEM, TEM, DLS, FTIR, XRD, VSM, and nitrogen physisorption. IO-MMNs exhibited relatively high surface areas and large pore volumes (S_BET = 70–120 m²/g and V_pore = 0.25–0.45 cm³/g), small sizes (~300 nm), good crystallinity and magnetization, and excellent biocompatibility. With their intrinsic porosities, high drug loading efficiencies (up to 70%) were achieved and the drug release rates were found to be pH-dependent. Cytotoxicity, confocal microscopy, and flow cytometry experiments against different types of cancerous cells indicated that Dox-loaded IO-MMNs reduced the viability of metastatic MCF-7 and KAIMRC-1 breast as well as HT-29 colon cancer cells, with the least uptake and toxicity towards normal primary cells (up to 4-fold enhancement). These results strongly suggest the potential use of IO-MMNs as promising agents for enhanced and effective drug delivery in cancer theranostics.