Surface Functionalization Of Magnetic Nanoparticles Research Articles

Recent Advances in Surface Functionalization of Magnetic Nanoparticles

In recent years, significant progress has been made in the surface functionalization of magnetic nanoparticles (MNPs), revolutionizing their utility in multimodal imaging, drug delivery, and catalysis. This progression, spanning over the last decade, has unfolded in discernible phases, each marked by distinct advancements and paradigm shifts. In the nascent stage, emphasis was placed on foundational techniques, such as ligand exchange and organic coatings, establishing the groundwork for subsequent innovations. This review navigates through the cutting-edge developments in tailoring MNP surfaces, illuminating their pivotal role in advancing these diverse applications. The exploration encompasses an array of innovative strategies such as organic coatings, inorganic encapsulation, ligand engineering, self-assembly, and bioconjugation, elucidating how each approach impacts or augments MNP performance. Notably, surface-functionalized MNPs exhibit increased efficacy in multimodal imaging, demonstrating improved MRI contrast and targeted imaging. The current review underscores the transformative impact of surface modifications on drug delivery systems, enabling controlled release, targeted therapy, and enhanced biocompatibility. With a comprehensive analysis of characterization techniques and future prospects, this review surveys the dynamic landscape of MNP surface functionalization over the past three years (2021–2023). By dissecting the underlying principles and applications, the review provides not only a retrospective analysis but also a forward-looking perspective on the potential of surface-engineered MNPs in shaping the future of science, technology, and medicine.

Frequency and Amplitude Optimizations for Magnetic Particle Spectroscopy Applications

Nowadays, there is a growing interest in the field of magnetic particle spectroscopy (MPS)-based bioassays. MPS monitors the dynamic magnetic response of surface-functionalized magnetic nanoparticles (MNPs) upon excitation by an alternating magnetic field (AMF) to detect various target analytes. This technology has flourished in the past decade due to its low cost, low background magnetic noise interference from the biomatrix, and fast response time. A large number of MPS variants have been reported by different groups around the world, with applications ranging from disease diagnosis to foodborne pathogen detection and virus detection. However, there is an urgent need for guidance on how to optimize the sensitivity of MPS detection by choosing different types of MNPs, AMF modalities, and MPS assay strategies (i.e., volume- and surface-based assays). In this work, we systematically study the effect of AMF frequencies and amplitudes on the responses of single- and multicore MNPs under two extreme conditions, namely, the bound and unbound states. Our results show that some modalities such as dual-frequency MPS utilizing multicore MNPs are more suitable for surface-based bioassay applications, whereas single-frequency MPS systems using single- or multicore MNPs are better suited for volumetric bioassay applications. Furthermore, the bioassay sensitivities for these modalities can be further improved by a careful selection of AMF frequencies and amplitudes.

Five-Minute Magnetic Nanoparticle Spectroscopy-Based Bioassay for Ultrafast Detection of SARS-CoV-2 Spike Protein.

In this work, we report a 5-min magnetic particle spectroscopy (MPS)-based bioassay strategy. In our approach, surface-functionalized magnetic nanoparticles are incubated with target analytes at 37 °C with agitation for 3 min, and the MPS reading is then taken at the fifth minute. We prove the feasibility of 5 min ultrafast detection of SARS-CoV-2 spike protein with a detection limit below 5 nM (0.2 pmol). Our proposed 5-min bioassay strategy may be applied to reduce the assay time for other liquid-phase, volumetric biosensors such as NMR, quantum dots, fluorescent biosensors, etc.

THERMAL PROPERTIES OF PSS COATED COBALT ZINC FERRITE NANOPARTICLES SYNTHESIZED BY CO-PRECIPITATION METHOD

In this work Cobalt Zinc Ferrite nanoparticles Co1-xZnxFe2O4 for x = 0.25, 0.5 and 0.75 were synthesized via coprecipitation method. Annealing of all the samples was carried out at 700 ºC for 5 hours. To investigate the crystal structure XRD analysis was used which confirmed the ferrite structure of synthesized samples. Afterwards surface coating of all the samples was done by biocompatible polymer PSS. Surface functionalization of magnetic nanoparticles with PSS (Polystyrene Sulphonate) was confirmed by FTIR spectrum of samples from 2000 cm-1 to 4000 cm-1 . Thermal properties and temperature variation with oscillating magnetic field was investigated by RF induction method. That showed increasing temperatures with decreasing concentration of Zinc content.Also Increase in temperature was observed directly related to the frequency of applied magnetic field and concentration of Cobalt in the sample. SAR values for the sample were estimated using specific heat of samples and temperature slope and it was observed that SAR is directly related to cobalt content as well as inversely to the Zn content in the samples.

Thermal Analysis of Crosslinking Reactions in Epoxy Nanocomposites Containing Polyvinyl Chloride (PVC)-Functionalized Nickel-Doped Nano-Fe3O4

This work reports on the thermal analysis of epoxy containing polyvinyl chloride (PVC) surface-functionalized magnetic nanoparticles (PVC–S/MNP) and its bulk-modified nickel-doped counterpart (PVC–S/MNP/Bi–B). Nanoparticles were synthesized through the cathodic electro-deposition method. The morphology of particles was imaged on a field-emission scanning electron microscope (FE-SEM), while X-ray diffraction analysis and Fourier-transform infrared spectroscopy (FTIR) were used to detect changes in the structure of nanoparticles. The magnetic behavior of particles was also studied by vibrating sample magnetometry (VSM). In particular, we focused on the effect of the bulk (Ni-doping) and surface (PVC-capping) modifications of MNPs on the thermal crosslinking of epoxy using nonisothermal differential scanning calorimetry (DSC) varying the heating rate. The cure labels of the prepared nanocomposites were assigned to them, as quantified by the cure index. The good cure state was assigned to the system containing PVC–S/MNP/Bi–B as a result of excessive ring opening of epoxy. Cure kinetics parameters of PVC–S/MNP/Bi–B incorporated epoxy was obtained by the use of isoconversional methodology. The activation energy of epoxy was decreased upon addition of 0.1 wt% of PVC–S/MNP/Bi–B due to the reaction of Cl− of PVC by the functional groups of resin.

Simple surface functionalization of magnetic nanoparticles with methotrexate‐conjugated bovine serum albumin as a biocompatible drug delivery vehicle

Magnetic nanoparticles (MNPs) functionalized with methotrexate (MTX)‐conjugated bovine serum albumin (BSA) as a biocompatible drug delivery vehicle were synthesized using a facile method. Characterization of the functionalized MNPs (Fe3O4@BSA‐MTX NPs) was performed using various techniques including UV–visible spectroscopy, dynamic light scattering, vibrating sample magnetometry and X‐ray diffraction. The particle size and zeta potential of Fe3O4@BSA‐MTX NPs were 105.7 ± 3.81 nm (mean ± SD) and −18.2 mV, respectively. MTX release from Fe3O4@BSA‐MTX NPs showed an enzyme‐dependent release pattern. Hemo‐biocompatibility of Fe3O4@BSA‐MTX NPs was confirmed using hemolysis test. In addition, the cytotoxicity of functionalized MNPs and free MTX against MCF‐7 cell line was investigated using MTT assay. The results of experiments revealed that the Fe3O4@BSA‐MTX NPs as a biocompatible carrier could improve the therapeutic effect of MTX.

DNA-Iron Oxide Nanoparticles Conjugates: Functional Magnetic Nanoplatforms in Biomedical Applications.

The use of magnetic nanoparticles (MNPs), such as iron oxide nanoparticles (IONPs), in biomedicine is considered to be a valuable alternative to the more traditional materials due to their chemical stability, cost-effectiveness, surface functionalization, and the possibility to selectively attach and transport targeted species to the desired location under a magnetic field. One of the many main applications of MNPs is DNA separation, which enables genetic material manipulation; consequently, MNPs are used in numerous biotechnological methods, such as gene transfection and molecular recognition systems. In addition, the interaction between the surfaces of MNPs and DNA molecules and the magnetic nature of the resulting composite have facilitated the development of safe and effective gene delivery vectors to treat significant diseases, such as cancer and neurological disorders. Furthermore, the special recognition properties of nucleic acids based on the binding capacity of DNA and the magnetic behavior of the nanoparticles allowing magnetic separation and concentration of analytes have led to the development of biosensors and diagnostic assays; however, both of these applications face important challenges in terms of the improvement of selective nanocarriers and biosensing capacity. In this review, we discuss some aspects of the properties and surface functionalization of MNPs, the interactions between DNA and IONPs, the preparation of DNA nanoplatforms and their biotechnological applications, such as the magnetic separation of DNA, magnetofection, preparation of DNA vaccines, and molecular recognition tools.

Cr(VI) Adsorption on Engineered Iron Oxide Nanoparticles: Exploring Complexation Processes and Water Chemistry.

Surface-functionalized magnetic nanoparticles are promising adsorbents due to their large surface areas and ease of separation after contaminant removal. In this work, the affinity of Cr(VI) adsorption to 8 nm surface-functionalized superparamagnetic magnetite nanoparticles was determined for surface coatings with amine (trimethyloctadecylammonium bromide, CTAB) and carboxyl (stearic acid, SA) functional groups. Cr(VI) adsorbed more strongly to the CTAB-coated nanoparticles than to the SA-coated materials due to electrostatic interactions between positively charged CTAB and anionic Cr(VI) species. The adsorption of Cr(VI) by CTAB- and SA-coated nanoparticles increased with decreasing pH (4.5-10), which could be simulated by a surface complexation model. Cr(VI) removal performance by the nanocomposite was evaluated for two realistic drinking water compositions. The co-occurrence of divalent cations (Ca2+ and Mg2+) and Cr(VI) resulted in decreased Cr(VI) adsorption as particles were destabilized, leading to the aggregation and lower effective surface area, confirming the importance of the overall water composition on the performance of novel engineered nanomaterials for water treatment applications.

Magnetic Nanoclusters Coated with Albumin, Casein, and Gelatin: Size Tuning, Relaxivity, Stability, Protein Corona, and Application in Nuclear Magnetic Resonance Immunoassay.

The surface functionalization of magnetic nanoparticles improves their physicochemical properties and applicability in biomedicine. Natural polymers, including proteins, are prospective coatings capable of increasing the stability, biocompatibility, and transverse relaxivity (r2) of magnetic nanoparticles. In this work, we functionalized the nanoclusters of carbon-coated iron nanoparticles with four proteins: bovine serum albumin, casein, and gelatins A and B, and we conducted a comprehensive comparative study of their properties essential to applications in biosensing. First, we examined the influence of environmental parameters on the size of prepared nanoclusters and synthesized protein-coated nanoclusters with a tunable size. Second, we showed that protein coating does not significantly influence the r2 relaxivity of clustered nanoparticles; however, the uniform distribution of individual nanoparticles inside the protein coating facilitates increased relaxivity. Third, we demonstrated the applicability of the obtained nanoclusters in biosensing by the development of a nuclear-magnetic-resonance-based immunoassay for the quantification of antibodies against tetanus toxoid. Fourth, the protein coronas of nanoclusters were studied using SDS-PAGE and Bradford protein assay. Finally, we compared the colloidal stability at various pH values and ionic strengths and in relevant complex media (i.e., blood serum, plasma, milk, juice, beer, and red wine), as well as the heat stability, resistance to proteolytic digestion, and shelf-life of protein-coated nanoclusters.

Ciprofloxacin-functionalized magnetic silica nanoparticles: as a reusable catalyst for the synthesis of 1H-chromeno[2,3-d]pyrimidine-5-carboxamides and imidazo[1,2-a]pyridines.

In this research, synthesis and characterization of new surface-functionalized magnetic silica nanoparticles are reported. The magnetic silica nanoparticle was synthesized by a silica coating of the magnetite nanoparticles through a sol-gel process, and then, their surface was modified by (3-chloropropyl)triethoxysilane and covalently functionalized by ciprofloxacin. The catalyst activity of prepared functionalized nanoparticle was investigated by isocyanide-based multicomponent reactions for the synthesis of 1H-chromeno[2,3-d]pyrimidine-5-carboxamides and imidazo[1,2-a]pyridines. This catalyst was recycled by magnetic filtration and reprocessed five times without having a significant loss of catalytic activity.

Surface functionalization of magnetic nanoparticles via palladium‐catalyzed Diels‐Alder approach

AbstractMetal nanoparticles are currently being used as substantial catalysts for a number of classical chemical transformations. In contrast, performing novel biochemical reactions with the help of nano‐organocatalysts is highly underdeveloped area in chemical synthesis. In order to prepare an efficient nano‐organocatalyst, facilitated stable covalent bonding would be achieved by using Diels‐Alder reactions on the surface of magnetic nanoparticles. Herein, we report the synthesis of magnetic nano‐organocatalysts by using Fe3O4 nanoparticle coated by SiO2 network and functionalized with vinylsilane, as dienophile moiety of Diels‐Alder reactions. In this work, palladium(II) is used as an instrumental catalyst for Diels‐Alder reaction, as well.

β-Cyclodextrin-Modified Magnetic Nanoparticles Immobilized on Sepharose Surface Provide an Effective Matrix for Protein Refolding.

In this article, we propose an impressive and facile strategy to improve protein refolding using solid phase artificial molecular chaperones consisting of the surface-functionalized magnetic nanoparticles. Specifically, monotosyl-β-cyclodextrin connected to the surface of 3-aminopropyltriethoxysilane (APES)-modified magnetic nanoparticles is immobilized on the sepharose surface to promote interaction with exposed hydrophobic surfaces of partially folded (intermediates) and unfolded states of proteins. Their efficiencies were investigated by circular dichroism spectroscopy and photoluminescence spectroscopy of the protein. Although the mechanism of this method is based on principles of hydrophobic chromatography, this system is not only purging the native protein from inactive inclusion bodies but also improving the protein refolding process. We chose β-cyclodextrin (β-CD) considering multiple reports in the literature about its efficiency in protein refolding and its biocompatibility. To increase the surface area/volume ratio of the sepharose surface by nanoparticles, more β-CD molecules are connected to the sepharose surface to make a better interaction with proteins. We suppose that proteins are isolated in the nanospace created by bound cyclodextrins on the resin surface so intermolecular interactions are reduced. The architecture of nanoparticles was characterized by Fourier transform infrared spectra, X-ray diffraction, scanning electron microscopy images, energy dispersive X-ray spectroscopy, nuclear magnetic resonance (1H NMR and 13C NMR), and dynamic light scattering.

Development of hyperbranched polymer encapsulated magnetic adsorbent (Fe3O4@SiO2–NH2-PAA) and its application for decontamination of heavy metal ions

The water dispersible magnetic adsorbent was fabricated by functionalization of magnetic nanoparticles (MNPs) with 3-aminopropyl trimethoxysilane (APTMS) and dendrimer-like polyamidoamine; the sorbent is named as Fe3O4@SiO2–NH2-PAA. The amine rich Fe3O4@SiO2–NH2-PAA adsorbent was further used in retrieval of heavy metal ions such as Cd(II), Co(II), Zn(II), Pb(II) and Cu(II) from the aqueous medium. Fabrication of Fe3O4@SiO2–NH2-PAA involves a two-step process: (i) surface initiation of MNPs by ligand exchange reaction and condensation of APTMS (Fe3O4@SiO2-NH2), (ii) surface functionalization of MNPs by controlled/living polymerization. Surface functional groups, crystallization characteristics, surface morphologies and magnetic properties of the adsorbent were analyzed by FT-IR, XRD, SEM, TEM, and VSM. The characterization outcomes showed that functionalization improved the oxygen and nitrogen atomic percentages of adsorbent resulting enriched adsorption. Sorption isotherm and kinetic models illustrated that sorption data better fitted to Langmuir isotherm model and pseudo-second order kinetic model. These results suggest that sorption process is monolayer and is chemical in nature. The order of sorption capacities (mgg−1) based on Langmuir isotherm model are: Pb(II) (108.82)>Cd(II) (100.81)>Co(II) (95.40)>Zn(II) (89.62)> Cu(II)(87.82). These findings suggest that as developed magnetic sorbent can be replaceable for traditional adsorbents due its high sorption performance, rapid kinetics, and magnetic separation characteristics.

Amelioration of H4[W12SiO40] by nanomagnetic heterogenization: For the synthesis of 1H–pyrazolo[1,2‐b]phthalazinedione derivatives

We conveniently coated silicotungstic acid (STA, H4[W12SiO40]) on amino‐functionalized Si–magnetite nanoparticles, as surface functionalization of magnetic nanoparticles is an excellent way for green and efficient catalysis. The nanoparticles were structurally characterized using various techniques. The catalytic activity and recyclability of the STA–amine–Si–magnetite nanoparticles were probed through synthesis of 1H–pyrazolo[1,2‐b]phthalazinedione derivatives. The reaction proceeds smoothly to provide products in excellent yields and short reaction times. The catalyst could be readily recovered using a simple external magnet and reused several times without any significant loss in activity. Herein, we report a comparison of the activity of H4[W12SiO40] as a homogeneous and heterogeneous catalyst, the latter being found to be more efficient. The findings offer effective methods for environmentally friendly synthesis of pyrazolo[1,2‐b]phthalazinedione derivatives.

Surface functionalized magnetic nanoparticles shift cell behavior with on/off magnetic fields.

Magnetic nanoparticles (MNPs) are used as contrast agents and targeted drug delivery systems (TDDS) due to their favorable size, surface charge, and magnetic properties. Unfortunately, the toxicity associated with MNPs limits their biological applications. Surface functionalization of MNPs with selective polymers alters the surface chemistry to impart better biocompatibility. We report the preparation of surface functionalized MNPs using iron oxide NPs (MNPs), poly (lactic-co-glycolic acid) (PLGA), and sodium alginate via co-precipitation, emulsification, and electro-spraying, respectively. The NPs are in the nanosize range and negatively charged. Morphological and structural analyses affirm the surface functionalized nanostructure of the NPs. The surface functionalized MNPs are biocompatible, and demonstrate enhanced intracellular delivery under an applied magnetic field (H), which evinces the targeting ability of MNPs. After NP treatment, the physico-mechanical properties of fibroblasts are decided by the selective MNP uptake under "on" or "off" magnetic field conditions. We envision potential use of biocompatible surface functionalized MNP for intracellular-, targeted-DDS, imaging, and for investigating cellular mechanics.

Catechol Derivative RAFT Agent for Surface Functionalization of Magnetic Nanoparticles

Functional nanoparticles (NPs), Fe 3 O 4 @SiO 2 -PMEMA, were prepared via surface initiated reversible addition-fragmentation chain transfer (RAFT) polymerization, using catechol-based biomimetic RAFT agent incorporating a trithiocarbonate unit and 2- N -morpholinoethyl methacrylate (MEMA) as the monomer. Poly(2- N -morpholinoethyl methacrylate) (PMEMA) were synthesized on biomimetic RAFT agent functionalized Fe 3 O 4 @SiO 2 NPs surface. The prepared NPs were characterized at the different modification stages using attenuated total reflectance -Fourier transform infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD), thermogravimetric analysis (TGA) and transmission electron microscope (TEM). The magnetic properties of NPs were also determined by vibrating sample magnetometer (VSM).

Synthesis and surface functionalization of Fe 3 O 4 -SiO 2 core-shell nanoparticles with 3-glycidoxypropyltrimethoxysilane and 1,1′-carbonyldiimidazole for bio-applications

Abstract In our research, we have presented the controlled synthesis of Fe 3 O 4 nanoparticles (NPs) with a size of about 10 nm coated with SiO 2 shells for bio-applications. On this basis, the controlled synthesis of Fe 3 O 4 -SiO 2 core-shell nanoparticles and their surface functionalization with 3-glycidoxypropyltrimethoxysilane (GPS) and 1,1′-carbonyldiimidazole (CDI) has been presented with a facile synthetic process. The as-prepared Fe 3 O 4 -SiO 2 -GPS-CDI core-multishell NPs can bind proteins. Therefore, recombinant protein A/G (pA/G) was efficiently coupled onto the surface of NPs via CDI groups, creating a complete coverage. Antibodies (αT IgG) were also conjugated on Fe 3 O 4 -SiO 2 -GPS-CDI-pA/G, i.e. 9 mg αT antibodies per 1 g NPs. After the surface functionalization of the magnetic nanoparticles, their superparamagnetism was reduced by a factor of about threefold in Fe 3 O 4 -SiO 2 , and fivefold in Fe 3 O 4 -SiO 2 -GPS-CDI-pA/G in comparison with that of the naked Fe 3 O 4 NPs. The NPs conjugated with αT IgG could bind and remove 1 × 10 5 cells per 0.25 mg NPs in vitro. Finally, the new models of surface functionalization of magnetic nanoparticles have been proposed for promising bioconjugations in our further research.

Synthesis of well-defined catechol polymers for surface functionalization of magnetic nanoparticles

Well-defined fluorescent functional polymers with terminal catechol groups were synthesized by SET-LRP under aqueous conditions for “grafting to” modification of iron oxide nanoparticles.

Magnetically labeled cells with surface-modified fe3 o4 spherical and rod-shaped magnetic nanoparticles for tissue engineering applications.

Magnetically targeted cells with internalized magnetic nanoparticles (MNPs) could allow the success of cell transplantation and cell-based therapies, overcoming low cell retention that occurs when delivering cells by intravenous or local injection. Upon magnetization, these cells could then accumulate and stimulate the regeneration of the tissue in situ. Magnetic targeting of cells requires a detailed knowledge between interactions of engineered nanomaterials and cells, in particular the influence of shape and surface functionalization of MNPs. For the first time, cellular internalization of amino surface-modified iron oxide nanoparticles of two different shapes (nanospheres or nanorods) is studied. MNPs show high cellular uptake and labeled cells could exhibit a strong reaction with external magnetic fields. Compared to nanorods, nanospheres show better internalization efficiency, and labeled cells exhibit strong transportation reaction with external magnetic fields. Contiguous viable cell-sheets are developed by magnetic-force-based tissue engineering. The results confirm that the developed magnetic-responsive nano-biomaterials have potential applicability in tissue engineering or cellular therapies.

Synthesis and Characterization of Au/Fe<sub>3</sub>O<sub>4</sub> Nanocomposite

A new kind of surface-functionalized magnetic nanoparticles was fabricated by surface modification of ferroferric oxide with monolayer-protected gold nanoparticles. Ferroferric oxide nanoparticles were firstly synthesized by co-precipitating Fe2+ and Fe3+ ions in base solution, and then coated with a layer of 3-aminopropyltriethoxysilane by silanization reaction. Gold nanoparticles were surface-attached with 2-mercapto-4-methyl-5-thiazoleacetic acid which were subsequently linked to the modified ferroferric oxide nanoparticles to produce Au/Fe3O4 composite materials. The outer layer of ligand (2-mercapto-4-methyl-5-thiazoleacetic acid) on Au/Fe3O4 can function as binding sites for drugs and biomolecules, whereas the innermost magnetic cores are able to respond to an externally applied magnetic field. The as-synthesized Au/Fe3O4 nanocomposite is superparamagnetic (31.4 emu/g), thus rendering it potentially applicable in magnetic drug delivery and bioseparation.