Preparation of PEG-grafted immunomagnetoliposomes entrapping citrate stabilized magnetite particles and their application in CD34+ cell sorting

Agronomic Investigation of Spray Dispersion of Metal-Based Nanoparticles on Sunflowers in Real-World Environments

In environmental and agronomic settings, even minor imbalances can trigger a range of unpredicted responses. Despite the widespread use of metal-based nanoparticles (NPs) and new bio-nanofertilizers, their impact on crop production is absent in the literature. Therefore, our research is focused on the agronomic effect of spray application of gold nanoparticles anchored to SiO₂ mesoporous silica (AuSi-NPs), zinc oxide nanoparticles (ZnO-NPs), and iron oxide nanoparticles (Fe₃O₄-NPs) on sunflowers under real-world environments. Our findings revealed that the biosynthetically prepared AuSi-NPs and ZnO-NPs were highly effective in enhancing sunflower seasonal physiology, e.g., the value of the NDVI index increased from 0.012 to 0.025 after AuSi-NPs application. The distribution of leaf trichomes improved and the grain yield increased from 2.47 t ha^-1 to 3.29 t ha^-1 after ZnO-NPs application. AuSi-NPs treatment resulted in a higher content of essential linoleic acid (54.37%) when compared to the NPs-free control (51.57%), which had a higher determined oleic acid. No NPs or residual translocated metals were detected in the fully ripe sunflower seeds, except for slightly higher silica content after the AuSi-NPs treatment. Additionally, AuSi-NPs and NPs-free control showed wide insect biodiversity while ZnO-NPs treatment had the lowest value of phosphorus as anti-nutrient. Contradictory but insignificant effect on physiology, yield, and insect biodiversity was observed in Fe₃O₄-NPs treatment. Therefore, further studies are needed to fully understand the long-term environmental and agricultural sustainability of NPs applications.

Magnetic properties of nanoparticles as a function of their spatial distribution on liposomes and cells

The aggregation processes of magnetic nanoparticles in biosystems are analysed by comparing the magnetic properties of three systems with different spatial distributions of the nanoparticles. The first one is iron oxide nanoparticles (NPs) of 14 nm synthesized by coprecipitation with two coatings, (3-aminopropyl)trimethoxysilane (APS) and dimercaptosuccinic acid (DMSA). The second one is liposomes with encapsulated nanoparticles, which have different configurations depending on the NP coating (NPs attached to the liposome surface or encapsulated in its aqueous volume). The last system consists of two cell lines (Pan02 and Jurkat) incubated with the NPs. Dynamic magnetic behaviour (AC) was analysed in liquid samples, maintaining their colloidal properties, while quasi-static (DC) magnetic measurements were performed on lyophilised samples. AC measurements provide a direct method for determining the effect of the environment on the magnetization relaxation of nanoparticles. Thus, the imaginary (χ'') component shifts to lower frequencies as the aggregation state increases from free nanoparticles to those attached or embedded into liposomes in cell culture media and more pronounced when internalized by the cells. DC magnetization curves show no degradation of the NPs after interaction with biosystems in the analysed timescale. However, the blocking temperature is shifted to higher temperatures for the nanoparticles in contact with the cells, regardless of the location, the incubation time, the cell line and the nanoparticle coating, supporting AC susceptibility data. These results indicate that the simple fact of being in contact with the cells makes the nanoparticles aggregate in a non-controlled way, which is not the same kind of aggregation caused by the contact with the cell medium nor inside liposomes.

Superparamagnetic iron oxide nanoparticles for in vivo molecular and cellular imaging

In the last decade, the biomedical applications of nanoparticles (NPs) (e.g. cell tracking, biosensing, magnetic resonance imaging (MRI), targeted drug delivery, and tissue engineering) have been increasingly developed. Among the various NP types, superparamagnetic iron oxide NPs (SPIONs) have attracted considerable attention for early detection of diseases due to their specific physicochemical properties and their molecular imaging capabilities. A comprehensive review is presented on the recent advances in the development of in vitro and in vivo SPION applications for molecular imaging, along with opportunities and challenges.

Magnetoliposomes and their potential in the intelligent drug-delivery field

Research advancements for magnetically guided drug delivery encompass not only the improvement of the design, synthesis and evaluation of more selective nanomaterials bearing magnetic properties, but also the optimization of the transport and delivery of magnetic agents. Such versatile platforms can be utilized for simultaneously carrying therapeutics and diagnostics.

Ultra magnetic liposomes for MR imaging, targeting, and hyperthermia

Magnetic liposomes offer opportunities as theranostic systems. The prerequisite for efficient imaging, tissue targeting or hyperthermia is high magnetic load of these vesicles. Here we describe the preparation of Ultra Magnetic Liposomes (UMLs), which may encapsulate iron oxide nanoparticles in a volume fraction of up to 30%. This remarkable magnetic charge provides UMLs with high magnetic mobilities, MRI relaxivities, and heating capacities for magnetic hyperthermia. Moreover, these UMLs are rapidly and efficiently internalized by cultured tumor cells and, when they are administered to mice, they can be vectorized to tumors by an external magnet.

Optimized synthesis of 100 nm diameter magnetoliposomes with high content of maghemite particles and high MRI effect

Magnetoliposomes are liposomes surrounding an iron oxide core, which are used as contrast enhancing agents in magnetic resonance imaging (MRI). One method for producing magnetoliposomes consists of hydration of a lipid film with citrate-coated iron oxide particles followed by extrusion. Two parameters are of major importance for in vivo applications of magnetoliposomes, namely their size, which must be small, optimally around 100 nm diameter, in order to ensure their prolonged circulation in the bloodstream, and their iron content, which must be maximal for generating high MRI effect. We studied the formation of magnetoliposomes by passive encapsulation of maghemite (γ-Fe(2)O(3)) particle suspensions of varying concentrations, with the objective of producing magnetoliposomes of small size and high iron content. The iron to lipid ratio was used to determine the iron content of the magnetoliposomes after the successive purification steps and cryo-TEM was used to characterize their size, their homogeneity and the efficiency of purification. The size of citrate-coated maghemite clusters was found to be of critical importance for obtaining magnetoliposomes smaller than 200 nm. We were able to reproducibly synthesize magnetoliposomes of 100 nm diameter with high iron content -up to 77 particles per liposome (5.6 moles iron per mole lipid) - and high r(2) MRI relaxivity - up to 320 m m(-1) . s(-1) . The magnetoliposomes present improved characteristics compared with previous reports. Future research will focus on using these magnetoliposomes as drug delivery systems for in vivo diagnostics or therapeutics applications.

Preparation and characterization of tegafur magnetic thermosensitive liposomes

The purpose was to study the preparation and properties of tegafur magnetic thermosensitive liposomes. The method was to employ an improved chemical coprecipitation method for preparing nano-magnetic particles and a reverse-phase evaporation and ultrasonic method for preparing tegafur magnetic thermosensitive liposomes. The results showed that tegafur magnetic thermosensitive liposomes were prepared successfully. They had comparatively strong magnetism and superparamagnetism, and their temperature showed a linear positive correlation with dosages and the field strength under a current value. The conclusion was that tegafur magnetic thermosensitive liposomes with comparatively small particle size, superparamagnetism and comparatively strong magnetism were prepared successfully.

Magnetoliposomes: versatile innovative nanocolloids for use in biotechnology and biomedicine

The high biocompatibility and versatile nature of liposomes have made these particles keystone components in many hot-topic biomedical research areas. Liposomes can be combined with a large variety of nanomaterials, such as superparamagnetic iron oxide nanocores. Because the unique features of both the magnetizable colloid and the versatile lipid bilayer can be joined, the resulting so-called magnetoliposomes can be exploited in a great array of biotechnological and biomedical applications. In this article, we highlight the use of magnetoliposomes in immobilizing enzymes, both water-soluble and hydrophobic ones, as well as their potential in several biomedical applications, including MRI, hyperthermia cancer treatment and drug delivery. The goal of this article is not to list all known uses of magnetoliposomes but rather to present some conspicuous applications in comparison to other currently used nanoparticles.

The in vitro kinetics of the interactions between PEG-ylated magnetic-fluid-loaded liposomes and macrophages

Binding and uptake kinetics of magnetic-fluid-loaded liposomes (MFL) by endocytotic cells were investigated in vitro on the model cell-line J774. MFL consisted of unilamellar phosphatidylcholine vesicles (mean hydrodynamic diameter close to 200nm) encapsulating 8-nm nanocrystals of maghemite (gamma-Fe(2)O(3)) and sterically stabilized by introducing 5mol% of distearylphosphatidylcholine poly(ethylene glycol)(2,000) (DSPE-PEG(2,000)) in the vesicle bilayer. The association processes with living macrophages were followed at two levels. On one hand, the lipid vesicles were imaged by confocal fluorescence microscopy. For this purpose 1mol% of rhodamine-marked phosphatidylethanolamine was added to the liposome composition. On the other hand, the iron oxide particles associated with cells were independently quantified by magnetophoresis. All the experiments were similarly performed with PEG-ylated or conventional MFL to point out the role of polymer coating. The results showed cell association with both types of liposomes resulting from binding followed by endocytosis. Steric stabilization by PEG chains reduced binding efficiency limiting the amount of MFL internalized by the macrophages. In contrast, PEG coating did not change the kinetics of endocytosis which exhibited the same first-order rate constant for both conventional and PEG-ylated liposomes. Moreover, lipids and iron oxide particle uptakes were perfectly correlated, indicating that MFL vesicle structure and encapsulation rate were preserved upon cell penetration.

Liposome–nanoparticle hybrids for multimodal diagnostic and therapeutic applications

Liposomes have a decade-long clinical presence as nanoscale delivery systems of encapsulated anthracycline molecules. However, their use as delivery systems of nanoparticles is still in the preclinical development stages. Liposome–nanoparticle hybrid constructs present great opportunities in terms of nanoscale delivery system engineering for combinatory therapeutic–imaging modalities. Moreover, many novel materials are being developed in nanotechnology laboratories that often require methodologies to enhance their compatibility with the biological milieu in vitro and in vivo. Liposomes are structurally suitable to make nanoparticles biocompatible and offer a clinically proven, versatile platform for the further enhancement of pharmacological efficacy. Small iron oxide nanoparticles, quantum dots, liposomes, silica and polystyrene nanoparticles have been incorporated into liposomes for a variety of different applications. In this review, all such liposome–nanoparticle hybrid systems are described, both in terms of their structural characteristics and the potential they offer as diagnostic and therapeutic multimodality agents.

Separation of CD34+ cells from human peripheral blood through polyurethane foaming membranes

Cell separation from peripheral blood was investigated using polyurethane (PU) foaming membranes and PU membranes (pore size, 5 or 12 mum) at different blood permeation speeds. Permeation ratio of hematopoietic stem cells (CD34(+) cells) through the PU membranes was the lowest among the blood cells at any blood permeation speed. This is thought to be because CD34(+) cells are more adhesive than red blood cells (RBCs), platelets, T cells, and B cells. Primitive hematopoietic stem and progenitor cells tend to adhere to the surface of mature blood cells, because of the high expression of cell-adhesion molecules on the surface of the cells. Human serum albumin solution was exposed to PU-COOH membranes to detach adhered cells from the surface of the membranes, allowing isolation of CD34(+) cells and reduction of RBCs in the permeate solution. Most purified CD34(+) cells (high recovery ratio of CD34(+) cells divided by recovery ratio of RBCs) were obtained in the recovery process using PU-COOH membranes (pore size, 5.2 microm) at a permeation speed of 0.3-1 mL/min.

Immunoliposome-mediated delivery of neomycin phosphotransferase for the lineage-specific selection of differentiated/committed stem cell progenies: potential advantages over transfection with marker genes, fluorescence-activated and magnetic affinity cell-sorting

A major challenge in the therapeutic application of stem cells in regenerative medicine is the lineage-specific selection of their committed/differentiated progenies for transplantation. This is necessary to avoid engraftment of undesired lineages at the transplantation site, i.e. fibroblastic scar tissue, as well as to enhance the efficacy of transplantation therapy. Commonly used techniques for lineage-specific selection of committed/differentiated stem cell progenies include marker gene transfection, fluorescence-activated (FACS) and magnetic-affinity (MACS) cell-sorting. Nevertheless, these have their disadvantages for therapeutic applications. Marker gene transfection invariably leads to permanent genetic modification of stem cells, which in turn limits their use in human clinical therapy due to overwhelming ethical and safety concerns. FACS requires expensive instrumentation and highly-skilled personnel, and is unsuited for handling bulk quantities of cells that would almost certainly be required for transplantation therapy. MACS is a cheaper alternative, but the level of purity attained is also reduced. A possible novel approach that has yet to be investigated is immunoliposome-mediated delivery of neomycin phosphotranferase (NPT) for lineage-specific selection of stem cell progenies. This would avoid permanent genetic modification to the cell, unlike recombinant NPT expression linked to activation of specific promoter sequences. Moreover, it could potentially provide a much more practical and cost-effective alternative for handling bulk quantities of cells that would be required for transplantation therapy, as compared to FACS or MACS. As such, this alternative approach needs to be rigorously investigated, in view of its potentially useful applications in stem cell therapeutics.

Cell separation between mesenchymal progenitor cells through porous polymeric membranes

This study investigates the separation of two types of marrow stromal cells, KUSA-A1 osteoblasts and H-1/A preadipocytes, by filtration through various porous polymeric membranes. It was found that KUSA-A1 permeates better than H-1/A cells through 12-microm polyurethane foaming membranes. This appears to be due to the relatively smaller cell size of KUSA-A1 cells. In addition, when feed solutions containing suspensions of either cell type or a mixture of the two were used, the permeation ratio was relatively low (< 6%) through polyurethane and surface-modified polyurethane foaming membranes. It was also found that there was some degree of separation between KUSA-A1 and H-1/A cells (separation factor = 1.8) with nylon-net filter membranes, but no separation was obtained when filters made of nonwoven fabrics or silk screens were used. This ability of the nylon-net filter membranes to separate the two cell types was due to a sieving effect that results from an optimal pore size. Finally, permeation of a solution of human serum albumin through the membrane following filtration of the cells did not result in a separation of cells in the recovery solution.

Cell separation of hepatocytes and fibroblasts through surface-modified polyurethane membranes

The separation of fibroblast cells (L929 cells) and hepatocytes was investigated by using unmodified and surface-modified polyurethane (PU) foaming membranes (pore size of 12 microm) by the incorporation of various functional groups. L929 cells permeated more readily than hepatocytes, and very few populations of hepatocytes (<5%) permeated through the membranes. This result was thought to be due to the smaller cell size of the L929 cells (5-10 microm) relative to the hepatocytes (15-30 microm). The larger hepatocytes were thought to plug the pores of the membranes. A good cell separation between L929 cells and hepatocytes was achieved when the cell mixture permeated through the negatively charged PU membranes. The negatively charged membranes were thought to enhance the permeation of L929 cells because of the electrostatic repulsion between the membranes and negatively charged cells. On the other hand, the hepatocytes were unable to permeate through the membranes because of the sieve effect caused by their large cell size. The separation of hepatocytes isolated from mice at different ages was also accomplished by permeating the cell mixture through unmodified and surface-modified PU membranes.

In vitro cytotoxic study of immunoliposomal doxorubicin targeted to human CD34+ leukemic cells

The expression of CD34 antigen in acute myelogenous leukemias is considered an unfavourable prognosis marker for response to anticancer drugs and duration of remission. This study investigated the applicability of long-circulating immunoliposomes loaded with doxorubicin targeted to CD34 antigen present on MDR(+) human myelogenous leukemia KG-1a cell line. Immunoliposomal doxorubicin showed a higher cytotoxicity against KG-1a cells than non-targeted liposomal doxorubicin, but it did not improve over that of free drug. Although no reversal of doxorubicin resistance was found to occur through its liposomal encapsulation, a therapeutic benefit can be obtained by the selective cytotoxicity observed. Endocytosis studies demonstrated that, after binding to CD34 antigen, the immunoliposomes are not internalized by the KG-1a cells and so the cytotoxic effect might be due to drug released into the space near the cell membrane. Thus, immunotargeting of liposomal doxorubicin to CD34(+) leukemic cells may only provide an ex vivo strategy for site-selective CD34(+) leukemia cell killing.

Magnetic alginate microparticles for purification of $alpha;-amylases

Spherical magnetic alginate microparticles (25-60 microm in diameter) were prepared using the microemulsion system, with water-saturated 1-pentanol as the organic phase. The limited solubility of 1-pentanol in water enabled simple removal of the organic solvent from the prepared beads with water solution. The prepared alginate microparticles were used as magnetic affinity adsorbents for specific purification of alpha-amylases. Enzyme activity was eluted by 1.0 M maltose. alpha-Amylases from Bacillus amyloliquefaciens and porcine pancreatic acetone powder were purified 9- and 12-fold with 88 and 96% activity recovery, respectively.

Peripheral blood cell separation through surface-modified polyurethane membranes

Cell separation from peripheral blood was investigated using surface-modified polyurethane (PU) membranes with different functional groups. Both red blood cells and platelets could pass through unmodified PU and PU-SO(3)H membranes, whereas the red blood cells preferentially passed through PU-N(C(2)H(5))(2) and PU-NHC(2)H(4)OH membranes. The permeation ratio of T and B cells was <25% for the surface-modified and unmodified PU membranes. CD34(+) cells have been recognized as various kinds of stem cells including hematopoietic and mesenchymal stem cells. The adhesiveness of CD34(+) cells on the PU membranes was found to be higher than that of red blood cells, platelets, T cells, or B cells. Overall, the adhesiveness of blood cells on the PU membranes increased in the following order: red blood cells </= platelets < T cells </= B cells < CD34(+) cells. Treatment of PU-COOH membranes with a human albumin solution to detach adhered blood cells, allowed recovery of mainly CD34(+) cells in the permeate, whereas both red blood cells and platelets could be isolated in the permeate using unmodified PU membranes. The PU membranes showed different permeation and recovery ratios of specific cells depending on the functional groups attached to the membranes.

Magnetite tattoos

BACKGROUND AND OBJECTIVES

Tattoo removal is a significant problem. The extraction of magnetite (Fe(3)O(4)) ink tattoos by a magnetic field was investigated, with and without Q-switched laser treatment.

STUDY DESIGN/MATERIALS AND METHODS

Magnetite particles (1.4 microm) were used to make mature, black skin tattoos on hairless albino rats. A Q-switched ruby laser (QSRL) 3.5 J/cm(2), 6.5-mm spot size, 40-nanosecond pulse width was used for treatment. Permanent magnets (1.4 T, 6-mm diameter) were tested to extract the magnetite particles, alone and after QSRL. Lightening of treated tattoos was measured from digital photographs, and the amount and distribution of magnetite in skin biopsies was scored blindly.

RESULTS

External application of magnets on mature magnetite tattoos without prior QSRL treatment, did not significantly extract, lighten, darken, or change their histologic appearance. A magnetic field applied immediately after QSRL treatment extracted some ink when epidermal injury was present, and caused significant redistribution of magnetite into the upper dermis with vertical banding along magnetic field lines. When applied for 3 weeks following QSRL, magnets caused darkening of tattoos.

CONCLUSIONS

Magnetite skin tattoos can be manipulated by external magnets, especially after Q-switched laser treatment. Magnetically-extractable tattoos may be feasible.