Aggregation of magnetic chitosan based nanoparticles and their application in controlled drug release

Novel less than 100 nm sized magnetic Co_0.5Mn_0.5Fe₂O₄-chitosan nanoparticles advantageous in respect of excellent biodegradation and high level of controllability are successfully prepared. TEM and SEM images showed the cubic-shape magnetic Co_0.5Mn_0.5Fe₂O₄ particles were encapsulated by spherical chitosan nanoparticles. The release behavior of bovine serum albumin entrapped in the particles was of distinctly difference with the changes of pH value of loading medium. The release of bovine serum albumin in those two kinds of particles in the medium of pH=1.0 was much quicker in pH = 7.4 and 9.18. The amount of Bovine serum albumin (BSA) released from the particles at different time intervals was estimated using UV spectrophotomertic method at 279 nm. The dissolution profile and in vitro release kinetics showed that Co_0.5Mn_0.5Fe₂O₄-chitosan nanoparticles were promising for controlled delivery of the drug.     

Synthesis of magnetic nanoparticles and their application to bioassays

Magnetic nanoparticles have been attracting much interest as a labeling material in the fields of advanced biological and medical applications such as drug delivery, magnetic resonance imaging, and array-based assaying. In this review, synthesis of iron oxide magnetic nanoparticles via a reverse micelle system and modification of their surface by an organosilane agent are discussed. Furthermore, as a practical biological assay system, the magnetic detection of biomolecular interactions is demonstrated by using the combination of a patterned substrate modified with a self-assembled monolayer and the magnetic nanoparticles.     

Synthesis and characterization of magnetic nanoparticles

Magnetic nanoparticles with average diameter in the range of 6.4-8.3 nni have been synthesized by a chemical co-precipitation of Fe(Ⅱ)and Fe(Ⅲ)salts in 1.5 M NH4OH solution.The size of the magnetic particles is dependent on both temperature and the ionic strength of the iron ion solutions.The magnetic particles formed at higher temperature or lower ionic strength were slightly larger than those formed at lower temperature or higher ionic strength respectively.In spite of the different reaction conditions,all the resultant nanoparticles are nearly spherical and have a similar crystalline structure.At 300 K,such prepared nanoparticles are superparam-agnetic.The saturation magnetizations for 7.8 and 6.4 nm particles are 71 and 63 emu/g respectively,which are only ~ 20-30% less than the saturation magnetization(90 emu/g)of bulk Fe3O4 Our results indicated that a control of the reaction conditions could be used to tailor the size of magnetic nanoparticles in free precipitation.     

Synthesis and electrochemical investigation of spinel cobalt ferrite magnetic nanoparticles for supercapacitor application

Cobalt ferrite magnetic nanoparticles (CoFe₂O₄-MNPs) were synthesized by hydrothermal and co-precipitation methods using different precursors such as nitrates, chlorides, and acetates, at different concentrations with/without surfactant under different growth conditions. The structural and morphological analyses reveal the formation of a single-phase CoFe₂O₄ in nanoplatelet-shaped NPs with average particle size between 11 and 26 nm depending on synthesis condition. The specific surface area of these NPs obtained by hydrothermal method was ~ 34 m² g^?1. Electrochemical performances of the obtained nanoparticles in a three-electrode configuration with a 6 M KOH electrolyte revealed a specific capacitance (C _s) of 429 F/g at 0.5 A/g, with excellent capacitance retention of 98.8% after 6000 cycles at 10 A/g for the electro-active NPs synthesized by hydrothermal method at 200 °C for 18 h.     

Synthesis of d-f coordination polymer nanoparticles and their application in phosphorescence and magnetic resonance imaging

Magneto-phosphorescent d-f coordination polymer nanoparticles (f-CPPs) were conveniently synthesized by phosphorescent carboxyl-functionalized iridium complexes as building blocks and magnetic Gd(III) ions as metallic nodes. They reveal uniform hollow spheres with an average diameter of around 60 nm and wall thickness of about 10 nm. Water soluble f-CPPs were obtained by polyvinylpyrolidone modification (denoted as f-CPPs@PVP), which had an intense red phosphorescence, moderate longitudinal relaxivity (r(1)) and low cytotoxicity. Furthermore, inductively coupled plasma atomic emission spectroscopy (ICP-AES) and confocal laser scanning microscopy (CLSM) confirmed f-CPPs@PVP could be taken up by living cells effectively. Therefore, they should be a novel nano-bioprobe for the multimodal imaging of cancer cells.     

Synthesis of iron oxide nanoparticles using chitosan and starch templates

Natural polymers like chitosan and starch have been employed as templates for the preparation of iron oxide nanoparticles. The templates offer selective binding sites for Fe(II) under aqueous conditions. Controlled drying and subsequent removal of the template backbone enables the synthesis of spatially separated iron oxide nanoparticles. The crystalline character of the iron oxide and near narrow particle size distribution pattern have been confirmed through powder XRD, Photon Correlation Spectroscopy, and TEM measurements. The crystallite sizes of the particles were found to be 26–35 nm irrespective of the nature of the template.     

磁性壳聚糖微球的制备和应用

磁性壳聚糖微球是通过一定的方法用壳聚糖将磁性材料包埋而形成的磁性微球,其内核为纳米级的磁性金属微粒,外层为壳聚糖.壳聚糖含有大量的氨基和羟基,使其具有特定的理化性质,由此奠定了壳聚糖的许多生物学特性及加工特性的基础.另一方面,其磁性内核使磁性壳聚糖微球具有很好的顺磁性,利用外加磁场可以很方便地进行分离.因此磁性壳聚糖在固定化酶、污水处理、食品工业和生物医药等方面具有广泛的用途,磁性壳聚糖的制备及应用的相关研究也越来越受到重视.本文作者对磁性壳聚糖微球的制备和应用进行评述.     

Synthesis and characterization of PEG modified N-trimethylaminoethylmethacrylate chitosan nanoparticles

Chitosan-N-trimethylaminoethylmethacrylate chloride-PEG (CS-TM-PEG) copolymers were synthesized in order to improve the solubility of chitosan in physiological environment, and enhance the biocompatibility of quaternized chitosan. The result of ¹H NMR confirmed that PEG had been combined with amino groups of quaternized chitosan. The profile of hemolysis assay showed that Chitosan-N-trimethylaminoethylmethacrylate chloride (CS-TM) copolymer exhibited hemolytic activity from 10.31% to 13.58%, while CS-TM-PEG copolymer had hemolytic activity from 4.76% to 7.05% at copolymer concentrations from 250 to 2000 μg/ml. Through PEG modification, the hemolytic activity could be reduced to a half. CS-TM-PEG copolymer-insulin nanoparticles were prepared based on ionic gelation process of positively charged copolymers and negatively charged insulin. The nanoparticles were characterized in terms of particle size, TEM, association efficiency and in vitro release. These nanoparticles were 200-400 nm in size and insulin association efficiency of optimal formulations was found up to 90%. In vitro release showed that the nanoparticles provided an initial burst release followed by a sustained release with the sensitivity of ionic strength and pH values.     

Synthesis of magnetic nanoparticles for analytical applications

A simple method based on magnetically assisted chemical separation has been developed for analytical purposes. In this method, morin-modified magnetic nanoparticles were used for the selective extraction and preconcentration of copper ions from aqueous solutions. The influence of different parameters, such as the presence of the morin extractant, the amount of morin extractant loaded on the nanoparticles, the pH, adsorption time and the type and minimum amount of eluent required for elution of the copper from the magnetic nanoparticles, were evaluated. The detection limit of the proposed method followed by ICP–OES was found to be 1.3 µg L^?1 and a dynamic linear range of 10–200 µg L^?1 was obtained. The relative standard deviation was less than 5%. The method was applied to the recovery and determination of copper in real samples.     

Surface modification of magnetic nanoparticles with alkoxysilanes and their application in magnetic bioseparations

A versatile and inexpensive method for the introduction of amine groups onto the surface of silica-coated magnetite composite nanoparticles has been established based on the condensation of (aminopropyl)triethoxysilane (APTS). The process was observed to be sensitive to a range of variables, and a range of silane surface-modified nanoparticles was synthesized under various reaction conditions, that is, solvent systems [water, tetrahydrofuran (THF), ethanol, or 1:1 mixtures of them], reaction times (from 1 to 24 h), and temperatures (18, 50, and 70 degrees C), with water as the catalyst and silane at either 0.2% or 2% (w/v) in an attempt to optimize the process. The products of the various reactions were characterized in terms of their possession of surface -NH2 groups, morphologies, and properties with respect to DNA binding and elution before being modified with a single-stranded oligonucleotide capture sequence. It was observed that careful manipulation of temperature, time, and solvent conditions was important for optimal silanization of the nanoparticles, and in our experiments best results were obtained when silanization of the particles in suspension involved use of water as the solvent and APTS at 0.2% (w/v) and when the reaction was conducted at room temperature for 5 h and was preceded by ultrasonication of the particle suspension. The materials produced were used in experiments to selectively capture complementary nucleic acid sequences by hybridization after grafting with an oligonucleotide. The efficiency of the oligonucleotide-modified particles in the capture experiments was observed to be directly related to the original density of amine groups present at the surface of the support. The results indicate that surface engineering of the nanoparticles was possible by silanization under defined, optimized conditions. This approach could be extended to the activation of such surfaces and other materials with other functional groups.     

磁性铁氧化物纳米粒子制备及其体内应用研究

磁性铁氧化物纳米粒子由于其生物相容性和低毒性而广泛的应用于生物医学领域。本文总结了近年来制备各种磁性铁氧化物纳米粒子的方法,比较了它们在粒径、结晶度以及制备条件等方面的优缺点,概括了对其进行表面修饰改性材料的种类,阐述近年来磁性铁氧化物纳米粒子在体内应用中药物运输、磁共振成像、磁热疗方面的进展,并指出当前应用中的主要方向和亟待解决的问题。     

Self-aggregated nanoparticles from linoleic acid modified carboxymethyl chitosan: Synthesis, characterization and application in vitro

The purpose of the present research work was to study the formation of linoleic acid (LA) modified carboxymethyl chitosan (LCC). Another objective was to evaluate effect of linoleic acid degree of substitution on loading capacity (LC), ADR loading efficiency (LE) and in vitro release profile of LCC nanoparticles. The hydrogel nanoparticles can be prepared using linoleic acid modified carboxymethyl chitosan (LACMCS) after the sonication. The critical aggregation concentration (CAC) of the self-aggregate of LA modified CMCS (LCC) was determined by measuring the fluorescence intensity of the pyrene as a fluorescent probe. The CAC values were in the range of 0.061–0.081 mg/mL. Self-aggregated nanoparticles exhibited an increased LC and LE, decreased sustained release with an increasing ratio of the hydrophobic LA to hydrophilic CMCS. LCC nanoparticles loaded with ADR exerted in vitro anticancer activity against Hela cells that was comparable to the activity of free (non-entrapped in nanoparticles) ADR.     

Synthesis of hollow magnetic and luminescent bifunctional composite nanoparticles

Composite nanoparticles consisted of Au-coating Co superparamagnetic cores and CdSe shells have been synthesized. In-situ reduction and cation exchange methods have been applied in the synthetic process. The composite nanoparticles have been characterized by various methods. Experimental results showed that the oxidation of cobalt nanoparticles might be restrained by a gold shell. The as-prepared nanoconjugates exhibited magnetic and luminescent properties. The bifunctional nanoparticles can be used as detecting agent to analyze tumor cell in vitro and in vivo. We believe that the results could be used as a reference by researchers engaged in both fundamental and applied biomedicine.     

Characterization and analytical application of surface modified magnetic nanoparticles

Fe₃O₄ superparamagnetic nanoparticles with various functionalities were synthesized using a chemical co-precipitation method and used to demonstrate their analytical applications for protein separation of protein and metal ion extraction. The chemically inert silica layer coated with tetraethoxysilane (TEOS) protected the Fe₃O₄ core from a chemical attack and allowed the nanoparticles to be well dispersed in an aqueous solution. Particularly, the beads were resistant to an acidic solution with a pH ≥ 3. The amino (− NH₂) groups were covalently bonded to the silica coated Fe₃O₄, and then the carboxyl (− COOH) groups were functionalized to the nanoparticle surface through the reaction of − NH₂ and glutaric anhydride. The synthesized magnetic nanoparticles (MNP) were characterized using FT-IR, FE-TEM, XRD, and SQUID. The presence of functional groups on the nano beads was confirmed using molecular fluorescence spectrometry. For the presence of the amino (− NH₂) groups, FITC was tagged and monitored using an excitation laser with a wavelength of 473 nm and a fluorescence emission of 518 nm. Biotin was immobilized on the MNP and the fluorescent of FITC tagged on avidin was monitored to identify the carboxyl (− COOH) group.The proteins of Cytochrome C (12,000 Da), Rnase B (15,000 Da), and Myoglobin (17,000 Da) were separated using the MNP functionalized with the carboxyl (− COOH) group and identified using MALDI-TOF-MS. Amino benzyl EDTA (ethylenediaminetetraacetic acid) was immobilized on the MNP for metal–EDTA complexation to use the synthesized magnetic particles to extract metal ions for environmental and clinical application. Cu, Cd, Co, and Pb ions were extracted from ∼ 10 ng/mL solutions in the batch-type procedure and the extraction efficiency was > 90% at a pH of 4.     

Synthesis,characterization and properties of magnetic colloids supported on chitosan

This work proposes the synthesis, characterization and investigation of the stabilization capabilities of chitosan doped with magnetic nanoparticles. Nanoparticles of Fe, Co, Co(II,III) oxide, Ni and Ni/Ag mixture in 2-propanol were synthesized by chemical liquid deposition and the incorporation on the polymeric matrix was performed by solvated metal atom dispersion. Colloids and nanoparticles supported on chitosan were characterized by ultraviolet, Fourier-transform infrared, thermogravimetric analysis, electron diffraction X-ray and magnetic behaviour; transmission and field electronic scanning electron microscopy. The particle size distribution of colloids ranges from 6 to 50 nm with low particle stability due to flocculation after 120 days. The nanoparticles supported on chitosan had a particle size distribution of approximately between 10 and 80 nm, with low particle distribution; however, these particles do not flocculate because the matrix increases the stabilization of nanoparticles. All compounds present superparamagnetic behaviour at low temperature.     

PEO coated magnetic nanoparticles for biomedical application

This paper reports on the preparation, characterization and stealthiness of superparamagnetic nanoparticles (magnetite Fe₃O₄) with a 5 nm diameter and stabilized in water (pH ? 6.5) by a shell of water-soluble poly(ethylene oxide) (PEO) chains. Two types of diblock copolymers, i.e., poly(acrylic acid)-b-poly(ethylene oxide), PAA-PEO, and poly(acrylic acid)-b-poly(acrylate methoxy poly(ethyleneoxide)), PAA-PAMPEO, were prepared as stabilizers with different compositions and molecular weights. At pH ? 6.5, the negatively ionized PAA block interacts strongly with the positively-charged nanoparticles, thus playing the role of an anchoring block. Aggregates of coated nanoparticles were actually observed by dynamic light scattering (DLS) and transmission electron microscopy (TEM). The hydrodynamic diameter was in the 50-100 nm range and the aggregation number (number of nanoparticles per aggregate) was lying between several tens and hundred. Moreover, the stealthiness of these aggregates was assessed “in vitro” by the hemolytic CH50 test. No response of the complement system was observed, such that biomedical applications can be envisioned for these magnetic nanoparticles. Preliminary experiments of magnetic heating (10 kA/m; 108 kHz) were performed and specific absorption rate varied from 2 to 13 W/g_(Fe).     

Preparation of magnetic and fluorescent bifunctional chitosan nanoparticles for optical determination of copper ion

We describe a simple method for the synthesis of highly magnetic and fluorescent bifunctional chitosan nanoparticles (MF-CSNPs). Water-soluble and magnetic Fe3O4-chitosan nanoparticles and CdSe quantum dots capped with thioglycolic acid were incorporated into a chitosan matrix via electrostatic interaction. The optical, magnetic, crystallographic and morphological properties of the new nanoparticles were studied by UV-visible, fluorescence, X-ray diffraction and transmission electron microscopy. In addition, MF-CSNPs are found to be a useful probe for the determination of copper ion which acts as a quencher of fluorescence. The relative fluorescence intensity of MF-CSNPs is linearly related to the concentration of copper ion in the 0.125 to 25 ng·mL^-1 concentration range. The MF-CSNPs also are found to adsorb copper ion which therefore can be separated and enriched by manipulating them with an external magnetic field. Before enrichment, the limit of detection (LOD) for copper ion is 120 pg·mL^-1, but after enrichment, the LOD is 46 pg·mL^-1.

Synthesis of trisaccharide-coated magnetic nanoparticles for antibody removal

An efficient strategy for the synthesis of blood group A trisaccharide antigen has been developed. Magnetic nanoparticles having Fe₃O₄-Silica core-shell structure were prepared and functionalized with the prepared blood group A trisaccharide antigen derivative, and its excellent removal ability toward anti-A antibody was explored.     

Synthesis and characterization of pore size-tunable magnetic mesoporous silica nanoparticles

Magnetic mesoporous silica nanoparticles (M-MSNs) are emerging as one of the most appealing candidates for theranostic carriers. Herein, a simple synthesis method of M-MSNs with a single Fe(3)O(4) nanocrystal core and a mesoporous shell with radially aligned pores was elaborated using tetraethyl orthosilicate (TEOS) as silica source, cationic surfactant CTAB as template, and 1,3,5-triisopropylbenzene (TMB)/decane as pore swelling agents. Due to the special localization of TMB during the synthesis process, the pore size was increased with added TMB amount within a limited range, while further employment of TMB lead to severe particle coalescence and not well-developed pore structure. On the other hand, when a proper amount of decane was jointly incorporated with limited amounts of TMB, effective pore expansion of M-MSNs similar to that of analogous mesoporous silica nanoparticles was realized. The resultant M-MSN materials possessed smaller particle size (about 40-70 nm in diameter), tunable pore sizes (3.8-6.1 nm), high surface areas (700-1100 m(2)/g), and large pore volumes (0.44-1.54 cm(3)/g). We also demonstrate their high potential in conventional DNA loading. Maximum loading capacity of salmon sperm DNA (375 mg/g) was obtained by the use of the M-MSN sample with the largest pore size of 6.1 nm.