Polydopamine-coated Magnetic Nanoparticles Research Articles

Mg2+- or Ca2+-regulated aptamer adsorption on polydopamine-coated magnetic nanoparticles for fluorescence detection of ochratoxin A.

It has been observed that polyvalent metal ions can mediate the adsorption of DNA on polydopamine (PDA) surfaces. Exploiting this, we used two divalent metal ions (Mg2+ or Ca2+) to promote the adsorption of fluorescence-labelled ochratoxin A (OTA) aptamers on PDA-coated magnetic nanoparticles (Fe3O4@PDA). Based on the different adsorption affinities of free aptamers and OTA-bound aptamers, a facile assay method was established for OTA detection. The aptamers adsorbed on Fe3O4@PDA were removed via simple magnetic separation, and the remaining aptamers in the supernatant exhibited a positive correlation with the OTA concentration. The concentrations of Mg2+ and Ca2+ were finely tuned to attain the optimal adsorption affinity and sensitivity for OTA detection. In addition, other factors, including the Fe3O4@PDA dosage, pH, mixing order, and incubation time, were studied. Finally, under optimized conditions, a detection limit (3σ/s) of 1.26ng/mL was achieved for OTA. Real samples of spiked red wine were analysed with this aptamer-based method. This is the first report of regulating aptamer adsorption on the PDA surface with polyvalent metal ions for OTA detection. By changing the aptamers, the method can be easily extended to other target analytes.

Magnetically aligned composite membranes based on sulfonated poly(ether ether ketone) and phosphotungstic acid-loaded magnetic nanoparticles for fuel cell

In this work, phosphotungstic acid (HPW)-loaded polydopamine-coated magnetic nanoparticles (DMNPs@HPW) were prepared and incorporated into sulfonated poly(ether ether ketone) (SPEEK) matrix with magnetic field assistance to construct aligned channels to shorten proton transport pathways. The structure of the prepared composite membranes (M-SP/DMNPs@HPW) with magnetic field-induced proton channels was confirmed by SEM. The proton conductivity of M-SP/DMNPs@HPW-2 was significantly improved, with in-plane proton conductivity (σ//) of 159.3 mS/cm and through-plane proton conductivity (σ⊥) of 129.2 mS/cm in the hydrated state at 80 °C, which were 1.31 and 1.57 times higher than the pristine SPEEK membrane, due to the strong acidity of HPW and acid-base interaction of amine and sulfonic acid groups. Meanwhile, the σ⊥ of M-SP/DMNPs@HPW-2 was 1.14 times higher than that of SP/DMNPs@HPW-2 membrane prepared without magnetic field assistance. The fuel cell power output of M-SP/DMNPs@HPW-2 was 433 mW/cm2, while SP/DMNPs@HPW-2 and pristine SPEEK membranes tested under the same conditions were 360 mW/cm2 and 277 mW/cm2, respectively. The hydrogen crossover of M-SP/DMNPs@HPW-2 was slightly increased compared to SP/DMNPs@HPW-2 due to the construction of through-plane proton transport channels in the membrane.

Synthesis and Characterization of SPIONs Encapsulating Polydopamine Nanoparticles and Their Test for Aqueous Cu2+ Ion Removal

The removal of pollutants, such as heavy metals, aromatic compounds, dyes, pesticides and pharmaceuticals, from water is still an open challenge. Many methods have been developed and exploited for the purification of water from contaminants, including photocatalytic degradation, biological treatment, adsorption and chemical precipitation. Absorption-based techniques are still considered among the most efficient and commonly used approaches thanks to their operational simplicity. In recent years, polydopamine-coated magnetic nanoparticles have emerged for the uptake of heavy metals in water treatment, since they combine specific affinity towards pollutants and magnetic separation capacity. In this context, this work focuses on the synthesis of polydopamine (PDA)-coated Super Paramagnetic Iron Oxide Nanoparticles (PDA@SPIONs) as adsorbents for Cu2+ ions, designed to serve as functional nanostructures for the removal of Cu2+ from water by applying a magnetic field. The synthetic parameters, including the amount of SPIONs and PDA, were thoroughly investigated to define their effects on the nanostructure features and properties. Subsequently, the ability of the magnetic nanostructures to bind metal ions was assessed on Cu2+-containing solutions. A systematic investigation of the prepared functional nanostructures was carried out by means of complementary spectroscopic, morphological and magnetic techniques. Inductively coupled plasma atomic emission spectroscopy (ICP-AES) measurements were performed in order to estimate the Cu2+ binding ability. The overall results indicate that these nanostructures hold great promise for future bioremediation applications.

Selective Capture, Separation, and Photothermal Inactivation of Methicillin-Resistant Staphylococcus aureus (MRSA) Using Functional Magnetic Nanoparticles.

Antibiotic-free antimicrobial strategies are urgently needed to address the rapid evolution of antimicrobial resistance and transmission of multidrug-resistance bacterial infections. Herein, we fabricated polydopamine-coated porous magnetic nanoparticles (pMNPs@PDA) for effective separation and photothermal killing of methicillin-resistant Staphylococcus aureus (MRSA). Taking advantage of the excellent bacteria-affinitive property of polydopamine, the nanoparticles were anchored on the surface of bacteria, permitting rapid and efficient MRSA capture and separation with over 99% removal via the application of a magnetic field in 30 min. It was found, for the first time, that polydopamine-coated magnetic nanoparticles displayed a selective capture of Gram-positive bacteria when compared with Gram-negative bacteria. The selectivity was attributed to the preferable binding capability of pMNPs@PDA to peptidoglycan (PGN) of Gram-positive bacteria, compared to the lipopolysaccharide (LPS) of Gram-negative bacteria. With the magnetic separation and photothermal properties, pMNPs@PDA exhibited efficient killing of the captured MRSA under the irradiation of near-infrared (NIR) light. Cell cytotoxicity testing demonstrated good biocompatibility of the nanoparticles. These antibiotic-free nanoparticles capable of fast capture, separation, and inactivation of MRSA may be potentially used for water disinfection, blood purification, and treatment of bacterial infections.

Synthesis of urea-functionalized magnetic porous organic polymers Fe3O4@PDA@UPOPs for rapid extraction of fluoroquinolones in food samples

It is of great interest in the development of reliable strategies for efficient adsorption and enrichment of drug residues in sample pretreatment. In this paper, urea-based porous organic polymers (UPOPs) were synthesized by the atom economic polymerization reaction of 1,4-phenylene diisocyanate (PPDI) and 1,3,5-tris(4-aminophenyl)benzene (TAPB) under mild conditions. Inspired by the versatility of polydopamine (PDA) coating, the UPOPs were successfully decorated on PDA coated-magnetic nanoparticles (Fe 3 O 4 @PDA) via in situ catalyst-free polymerization to afford urea-functionalized porous organic polymers (Fe 3 O 4 @PDA@UPOPs). The synthesized adsorbents exhibited good stability, high hydrophicility, microporous and mesoporous structure. The applicability of Fe 3 O 4 @PDA@UPOPs was evaluated as effective adsorbents for the magnetic solid-phase extraction (MSPE) of fluoroquinolones (FQs) from food samples (milk, egg and chicken muscle). Combined with high-performance liquid chromatography tandem mass spectrometry (HPLC-MS/MS) analysis, the optimized method featured low adsorbents dosage (2 mg) and rapid extraction (2 min), which provided a wide linear range (0.1–200.0 ng/g, r ≥ 0.9991) and high sensitivity (LODs: 0.04–0.1 ng/g) for FQs determination. Furthermore, controllable magnetism enable the adsorbents could be easily recovered by external magnet and reused at least eight extraction cycles without decreasing the adsorption performance. • Urea-functionalized magnetic porous organic polymers (Fe 3 O 4 @PDA@UPOPs) were fabricated under mild conditions. • The functionalized magnetic adsorbents were characterized by FT-IR, SEM, XRD and TGA analysis. • Application of Fe 3 O 4 @PDA@UPOPs in MSPE-HPLC-MS/MS for fluoroquinolones (FQs) analysis was developed. • The established method is sensitive and efficient with low adsorbent dosage for the detection of FQs.

Immobilized α-glucosidase using polydopamine-coated magnetic nanoparticles for targeted screening of an active component from Toona sinensis

Toona sinensis is a traditional vegetable with rich nutrition and wide biological activity. In our previous study, an active composition against α-amylase was screened from T. sinensis by ligand fishing. To investigate the effect of T. sinensis on other targets of antidiabetes, in this work, α-glucosidase was immobilized on polydopamine-coated magnetic nanoparticles to further screen the compounds against α-glucosidase by ligand fishing. The enzyme activity test showed that the 70% ethanol extract of T. sinensis (crude sample) had weak α-glucosidase inhibitory activity, but after extraction with different solvents, the ethyl acetate extract showed the highest α-glucosidase inhibitory activity. After immobilization of α-glucosidase on polydopamine (PDA)-coated magnetic nanoparticles, the properties of the enzyme were characterized and determined, and then quercetin-3-O-α-L-rhamnopyranoside was screened by ligand fishing and isolated by high-speed counter-current chromatography using the two-phase solvent system composed of n-hexane-ethyl acetate-methanol-water (1:5:1:5, v/v). The results of enzymes assay showed that the screened compound (IC50 value of 374.94 ± 4.35 μg/mL) possessed moderate α-glucosidase inhibitory activity. The presented results not only proved that ligand fishing based on polydopamine-coated magnetic α-glucosidase was an effective method for the rapid discovery of natural active substances, but also further strengthened the evidence of antidiabetic effect of T. sinensis.

Polydopamine-coated magnetic nanoparticles for the determination of nitro musks in environmental water samples by stir bar sorptive-dispersive microextraction

Magnetic-based microextraction approaches have gained popularity in recent years due to the magnetic properties of the extraction phases allowing to handle them easier and more efficiently. This work describes a magnetic-based analytical method for the determination of the family of nitro musks in environmental water samples. These compounds have been of great concern due to their environmental impacts and potential health effects. The method is based on stir bar sorptive-dispersive microextraction (SBSDME) as extraction approach, prior to thermal desorption coupled to gas chromatography-mass spectrometry analysis (TD-GC-MS). For this purpose, polydopamine-coated cobalt ferrite magnetic nanoparticles (CoFe2O4@PDA) were used as extraction material. The main parameters involved in the extraction procedure (i.e., sorbent amount, extraction time and ionic strength) as well as in the thermal desorption step (i.e., temperature and desorption time) were evaluated in order to obtain the highest sensitivity. Under the selected conditions, the method showed good linearity, limits of detection and quantification in the low ng L−1 range, intra- and inter-day repeatability with RSD <15%, and high enrichment factors (178–640). Finally, the method was applied to four environmental water samples of different origin. Relative recovery values ranging from 91 to 120% highlighted that the matrices under consideration do not affect the extraction process. This work constitutes the first time in which nitro musks compounds were selectively extracted by taking advantage the high potential that magnetic-based microextraction techniques offer, specially SBSDME.

CuCl2 anchored on polydopamine coated-magnetic nanoparticles (Fe3O4@PDA/Cu(II)): Preparation, characterization and evaluation of its cytotoxicity, antioxidant, antibacterial, and antifungal properties

In recent years, biosynthesis of metallic nanoparticles has gained much attention for the treatment of fungal and bacterial diseases. The purpose of the study was preparation, characterization, and assessment of cytotoxicity, antioxidant, and antimicrobial properties of CuCl2 coordinated on polydopamine coated-magnetic nanoparticles (Fe3O4@PDA-CuCl2). These nanoparticles were characterized by FT-IR, FE-SEM, TEM, EDS, ICP, and XPS analysis. According to the TEM and SEM analysis, Fe3O4@PDA-CuCl2 showed uniform spherical morphology and average diameters of 10–20 ± 5 nm. In the biological part of this study, Fe3O4@PDA-CuCl2 have significant cell viability against HUVECs line, inhibitory activities against common free radical i.e., DPPH, antibacterial potentials against Gram-negative bacteria (Salmonella typhimurium, Listeria monocytogenes, Proteus mirabilis, Escherichia coli O157:H7, and Pseudomonas aeruginosa) and Gram-positive bacteria (Streptococcus pneumonia, Enterococcus faecalis, Staphylococcus saprophyticus, Staphylococcus aureus, and Bacillus subtilis), and antifungal properties against Candida guilliermondii, Candida parapsilosis, Candida albicans, Candida krusei, and Candida glabrata. The results of FT-IR, FE-SEM, TEM, EDS, ICP, and XPS confirm the biosynthesis of Fe3O4@PDA-CuCl2 with a notable amount of antioxidant, antimicrobial, and cutaneous wound healing effects.

Trace determination and characterization of ginsenosides in rat plasma through magnetic dispersive solid-phase extraction based on core-shell polydopamine-coated magnetic nanoparticles

Enrichment of trace bioactive constituents and metabolites from complex biological samples is challenging. This study presented a one-pot synthesis of magnetic polydopamine nanoparticles (Fe3O4@SiO2@PDA NPs) with multiple recognition sites for the magnetic dispersive solid-phase extraction (MDSPE) of ginsenosides from rat plasma treated with white ginseng. The extracted ginsenosides were characterized by combining an ultra-high-performance liquid chromatography coupled to a high-resolution mass spectrometry with supplemental UNIFI libraries. Response surface methodology was statistically used to optimize the extraction procedure of the ginsenosides. The reusability of Fe3O4@SiO2@PDA NPs was also examined and the results showed that the recovery rate exceeded 80% after recycling 6 times. Furthermore, the proposed method showed greater enrichment efficiency and could rapidly determine and characterize 23 ginsenoside prototypes and metabolites from plasma. In comparison, conventional methanol method can only detect 8 ginsenosides from the same plasma samples. The proposed approach can provide methodological reference for the trace determination and characterization of different bioactive ingredients and metabolites of traditional Chinese medicines and food.

Palladium(II) anchored on polydopamine coated-magnetic nanoparticles (Fe3O4@PDA@Pd(II)): A heterogeneous and core–shell nanocatalyst in Buchwald–Hartwig C–N cross coupling reactions

An efficient method was proposed to synthesize polydopamine (PDA)-coated Fe3O4 nanoparticles (Fe3O4@PDA). For the first time, effective deposition of Pd complex is explained by using Fe3O4@PDA as a core–shell magnetic coordinator and stabilizer agent. In this method, palladium ions were adsorbed on Fe3O4@PDA surfaces through immersion of the Fe3O4@PDA into a palladium plating bath. The structure, morphology and physicochemical features of the prepared particles were studied using various analytical methods including high resolution transmission electron microscopy (HR-TEM), field emission scanning electron microscope (FESEM), energy-dispersive X-ray spectroscopy (EDS), vibrating sample magnetometer (VSM), X-ray photoelectron spectroscopy (XPS), inductively coupled plasma (ICP), thermogravimetric analysis (TGA) and FT-IR spectroscopy. Core–shell Fe3O4@PDA/Pd(II) nanoparticles showed excellent catalytic performance as a reusable nanocatalyst in Pd-catalyzed Buchwald–Hartwig CN cross coupling reaction. A variety of aryl amines were prepared through reaction of aryl halides (chloride, bromide and iodide) and amines in high yields. The catalyst can be recycled and reapplied up to six cycles with no considerable change in its catalytic activity.

Oxo-vanadium immobilized on polydopamine coated-magnetic nanoparticles (Fe 3 O 4 ): A heterogeneous nanocatalyst for selective oxidation of sulfides and benzylic alcohols with H 2 O 2

Abstract Polydopamine (PDA)-coated Fe3O4 nanoparticles (Fe3O4@PDA) were synthesized through a simple and green procedure. In this study, for the first time, successful immobilization of oxo-vanadium (V=O) on surface of Fe3O4@PDA as a magnetic adsorbent and stabilizing agent. The structure, morphology and physicochemical properties of the synthesized nanocatalyst [VO(PDA)@Fe3O4] were characterized by different analytical techniques such as high resolution transmission electron microscopy (HRTEM), field emission scanning electron microscope (FESEM), energy-dispersive X-ray spectroscopy (EDS), vibrating sample magnetometer (VSM), X-ray photoelectron spectroscopy (XPS), inductively coupled plasma (ICP) and FT–IR spectroscopy. VO(PDA)@Fe3O4 nanoparticles illustrated high catalytic activity as a recyclable nanocatalyst in the chemoselective oxidation of sulfides to sulfoxides and benzylic alcohols to aldehydes using green oxidant of hydrogen peroxide in high-yield. The synthesized catalyst can be used several times with no considerable leaching and change in its activity. Both improvement of catalytic performance and easy separation for the reaction procedure were obtained because of the presence of oxo-vanadium and the magnetic core.

PEGylated polydopamine-coated magnetic nanoparticles for combined targeted chemotherapy and photothermal ablation of tumour cells

The integration of multifunctional therapeutic capabilities into a single nanosystem has attracted much attention for use as an efficient cancer therapy. However, developing biocompatible therapeutic nano-agents with desirable safety, efficiency, targeting, and synergistic effects remains challenging. Herein, we designed a class of multifunctional PEGylated magnetic nanoparticles (NPs) with a core-shell structure and polydopamine (PDA) coating, which were loaded with the anticancer drug doxorubicin (DOX) for simultaneous targeted chemotherapy and photothermal ablation of tumour cells. This nanosystem showed strong near-infrared absorption due to the polydopamine layer and was capable of magnetic field-guided drug delivery due to the superparamagnetism of the carrier. The resultant product exhibited excellent stability and biocompatibility in vitro due to the PEGylation of dopamine. Notably, the combination of chemotherapy and photothermal therapy had an evident synergistic effect on the ablation of tumour cells. This multifunctional nanoplatform has promising potential as an efficient therapeutic agent for multimodal cancer treatment.

Preparation of magnetic mesoporous carbon from polystyrene-grafted magnetic nanoparticles for rapid extraction of chlorophenols from water samples

A magnetic mesoporous carbon material (Fe3O4@C) was fabricated by carbonizing polystyrene grafted polydopamine-coated magnetic nanoparticles.

Preparation of polydopamine-coated magnetic nanoparticles for dispersive solid-phase extraction of water-soluble synthetic colorants in beverage samples with HPLC analysis

A facile and sensitive dispersive solid-phase extraction (D-SPE) method for the extraction and enrichment of four representative synthetic colorants prior to high performance liquid chromatography analysis was introduced. As highly efficient adsorbents, polydopamine-coated Fe3O4 nanoparticles (Fe3O4@PDA NPs) were prepared by a simple and green procedure. Several factors affecting the extraction efficiency, mainly including the polymerization time of dopamine, pH of the sample solution, the amount of adsorbent, extraction time and the desorption conditions, were systematically studied. Under the optimized conditions, the enrichment factors for the four colorants were both higher than 176. The limits of detection (LODs) for the established d-SPE-HPLC method were found to be 0.20–0.25μgL−1, which were lower than most chromatographic methods previously reported for synthetic colorant analysis. When used for quantitative analysis, wide linearity ranges (1–500μgL−1 for amaranth and Ponceau 4R, and 0.80–500μgL−1 for sunset yellow and allure red) were achieved with good correlation (R2≥0.9995). The developed method was also successfully applied to the analysis of colorants in beverage samples with satisfactory results, demonstrating its reliability and feasibility in real sample analysis.

Selective extraction of berberine from Cortex Phellodendri using polydopamine‐coated magnetic nanoparticles

A new extraction agent featuring dopamine self-polymerized on magnetic Fe3 O4 nanoparticles has been successfully synthesized and evaluated for the SPE of berberine from the extract of the traditional Chinese medicinal plant, Cortex Phellodendri. The nanoparticles prepared possessed a core-shell structure and showed super-paramagnetism. It was found that these polydopamine-coated nanoparticles exhibited strong and selective adsorption for berberine. Among the chemical components present in C. Phellodendri, only berberine was adsorbed by the nanoparticles and extracted by a following SPE procedure. Various conditions such as the amount of polydopamine-coated nanoparticles, desorption solvent, desorption time and equilibrium time were optimized for the SPE of berberine. The purity of berberine extracted from C. Phellodendri was determined to be as high as 91.3% compared with that of 9.5% in the extract. The established SPE protocol combined advantages of highly selective enrichment with easy magnetic separation, and proved to be a facile efficient procedure for the isolation of berberine. Further, the prepared polydopamine-coated magnetic nanoparticles could be reused for multiple times, reducing operational cost. The applicability and reliability of the developed SPE method were demonstrated by isolating berberine from three different C. Phellodendri extracts. Recoveries of 85.4-111.2% were obtained with relative standard deviations ranging from 0.27-2.05%.

Magnetic nanoparticles coated with different shells for biorecognition: high specific binding capacity

Modifying the surfaces of magnetic nanoparticles (MNPs) by the covalent attachment of biomolecules will enable their application as media for magnetically-assisted bioseparations. In this paper, we reported both the activity and specific binding capacity of ferritin antibodies on core-shell MNPs. The antibodies were covalently attached on silica-, silver- and polydopamine-coated MNPs by different methods. Anti-ferritin was bound onto the silica- or silver-coated MNPs by conventional methods using 3-aminopropyltriethoxysilane (APTES) or 11-mercaptoundecanoic acid (MUA), which was followed by activation of carboxyl groups by EDC/NHS. However with anti-ferritin immobilized onto the Fe3O4 nanoparticles modified with polydopamine, an in situ coating formed through the adhesive proteins. In addition, a great deal of anti-ferritin biomolecules covalently attached onto the MNPs. According to our results, the amounts of bound anti-ferritin onto the silica-, silver- and PDA-coated MNPs were 70, 75 and 95 μg anti-ferritin per mg MNP, respectively. In the experiments, polydopamine (PDA)-coated MNPs showed faster adsorption, more significant selectivity and a larger binding capacity than the others. Also, the equilibrium dissociation constants of the antigen-antibody complexes were determined on the anti-ferritin-immobilized MNPs. Silica-, PDA- and silver-coated MNPs had Kd values of 5.45 × 10(-7), 2.12 × 10(-7) and 3.91 × 10(-8) molL(-1), respectively. Based on these results, the affinity of the anti-ferritin for ferritin on the PDA-coated MNPs was approximately 10-fold higher than that on the silica- and silver-coated MNPs. In addition, among the anti-ferritin-immobilized silica-, silver- and PDA-coated MNPs, the PDA-coated MNPs showed the highest antigen selectivity values. As a result, anti-ferritin-immobilized PDA-coated MNPs represented a higher activity and stronger affinity for the specific antigen than the others.

Polydopamine-Coated Magnetic Nanoparticles for Enrichment and Direct Detection of Small Molecule Pollutants Coupled with MALDI-TOF-MS

Polydopamine-coated Fe(3)O(4) nanoparticles (Fe(3)O(4)@PDA NPs) were synthesized and applied as matrix for the detection of pollutants by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF-MS). The synthesis of Fe(3)O(4)@PDA NPs was accomplished in 30 min by in situ polymerization of dopamine without any toxic reagent. Using Fe(3)O(4)@PDA NPs as matrix of MALDI-TOF, eleven small molecule pollutants (molecular weight from 251.6 to 499.3), including Benzo(a)pyrene (BaP), three perfluorinated compounds (PFCs), and seven antibiotics, were successfully detected in either positive or negative reflection mode without background interference. Furthermore, the Fe(3)O(4)@PDA NPs can also enrich trace amounts of hydrophobic target, such as BaP, from solution to nanoparticles surface. Then the Fe(3)O(4)@PDA-BaP can be isolated through magnetic sedimentation step and directly spotted on the stainless steel plate for MALDI measurement. With Fe(3)O(4)@PDA NPs as adsorbent and matrix, we also realized the analysis of BaP in tap water and lake water samples. Thus, a magnetic solid-phase extraction (MSPE)-MALDI-TOF-MS method was established for the measurement of BaP.

Facile, high efficiency immobilization of lipase enzyme on magnetic iron oxide nanoparticles via a biomimetic coating

BackgroundImmobilization of lipase on appropriate solid supports is one way to improve their stability and activity, and can be reused for large scale applications. A sample, cost- effective and high loading capacity method is still challenging.ResultsA facile method of lipase immobilization was developed in this study, by the use of polydopamine coated magnetic nanoparticles (PD-MNPs). Under optimal conditions, 73.9% of the available lipase was immobilized on PD-MNPs, yielding a lipase loading capacity as high as 429 mg/g. Enzyme assays revealed that lipase immobilized on PD-MNPs displayed enhanced pH and thermal stability compared to free lipase. Furthermore, lipase immobilized on PD-MNPs was easily isolated from the reaction medium by magnetic separation and retained more than 70% of initial activity after 21 repeated cycles of enzyme reaction followed by magnetic separation.ConclusionsImmobilization of enzyme onto magnetic iron oxide nanoparticles via poly-dopamine film is economical, facile and efficient.