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Entrapment of β-FeO(OH) nanoparticles in human serum albumin: Preparation, characterization and hemocompatibility
... In this context, the primary evaluation of the possible toxic effects of AuNPs on blood cells is an essential topic for a safer application of such nanostructured materials [42]. With this purpose, studies regarding the hemocompatibility of nanoparticles have been performed in a number of reports [43][44][45][46]. Furthermore, this is a relevant study for the application of AuNPs in the development of new biocompatible electrochemical sensing platforms, aiming the detection of analytes in blood and tissue samples. ...
... This assay is a useful indicator to evaluate whether the interaction of nanoparticles with the cell membrane can lead to cytotoxicity effects, and it is based on the resistance of erythrocytes against the action of hemolytic agents [43]. In hypotonic salt solutions, erythrocytes absorb water from the external environment and become swelled, with the consequent disintegration of the cell membrane and release of the intracellular hemoglobin (hemolysis). ...
... In solutions containing NaCl in concentrations around 0.5% and above, the erythrocyte plasma membrane normally remains stable, and no detectable hemolysis takes place [85,86]. If some compound or external agent to which the erythrocytes are exposed somehow destabilize the cell membrane, it is expected that the cells undergo hemolysis at salt concentrations higher than normal [43]. In this sense, we performed this assay in order to check the influence of AuNPs-PG and PG on the plasma membrane stability of red blood cells. ...
In the present work, gold nanoparticles were synthesized through a green route by using, for the first time,
polysaccharides extracted from pineapple gum (PG) as the reducing and capping agent. The obtained nanoparticles
(AuNPs-PG) were characterized by UV-VIS, FTIR, TEM, FESEM, EDX, XRD, and zeta potential measurements,
which confirmed that PG was effective to produce AuNPs with an average diameter of 10.3 ± 1.6 nm.
The AuNPs-PG were employed as the modifier of glassy carbon paste electrodes (CPE/AuNPs-PG), which were
applied as sensitive electrochemical sensors to the determination of the antihistamine drug promethazine hydrochloride
(PMZ). Cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) measurements
showed that the AuNPs-PG could enhance the electronic transfer properties of the glassy carbon paste, which was
due to their large surface area and high electrical conductivity. After optimization of the instrumental parameters
of square wave voltammetry (SWV) through a Box-Behnken factorial design, a linear relationship between the
anodic peak current and PMZ concentration was obtained in the range from 2.0 to 15.7 μmol L-1 in McIlvaine
buffer solution pH 5.0. The detection and quantification limits were found to be equal to 1.33 and 4.44 μmol L-1,
respectively. The developed sensors could successfully quantify PMZ in different commercial pharmaceutical
formulations, with satisfactory levels of accuracy and precision. In addition to improving the analytical features
of the electrodes, hemocompatibility assays carried out on erythrocytes and leukocytes showed that the AuNPs-
PG do not exhibit toxic effects on the referred cells. This interesting behavior enables their use in biocompatible
electrochemical sensing platforms as well as for future biomedical investigations.
... Fig. 2. represented the IR spectra of HSA NPs, Mt., SAP, SAP-HSA NPs, Mt-HSA NCs, and SAP-Mt-HSA NCs. The spectrum of HSA NPs displayed characteristic absorptions at 1650 cm −1 and 1520 cm −1 for C = 0 stretching of amide-I and NeH bending of amide-II, respectively, which belong to proteins (Angelova and Yordanov, 2017). The Si-O-Si stretching band at 1010 cm −1 in the spectrum of Mt. is widely used for its identification. ...
... According to ATR-FTIR analysis, it was assessed that both Mt. and SAP were successfully incorporated into HSA NPs. The spectrum of SAP-Mt-HSA NCs had peaks of amide bonds from HSA, SieO bond from Mt., and CeO bond from SAP (Almutairi and Ali, 2015;Angelova and Yordanov, 2017;Eng et al., 2013). ...
This study reports the synthesis and application of new saponin (SAP)-loaded montmorillonite-human serum albumin (Mt-HSA) nanocomposites (NCs) as an anticancer drug delivery agent. When the biodegradable and biofriendly HSA was combined with Mt., which possesses excellent mucoadhesive properties, the resulting NCs could pass through the gastrointestinal barrier easily. SAP-Mt-HSA NCs were prepared by a modified desolvation technique in which ethanol and glutaraldehyde (GA) were used as precipitating and crosslinking agents, respectively. The efficacy of these NCs was assessed in a colorectal cancer cell line (DLD-1) as an in-vitro gastrointestinal model and L929 fibroblast cells as a healthy cell model. The release profile of SAP and the cytotoxic effect and cellular uptake of NCs were evaluated. The results clearly demonstrated that SAP-Mt-HSA NCs can induce dose-dependent cancer cell death with little or no toxicity toward healthy cells.
... In pharmaceutics, this method is extensively applied for the encapsulation of drugs and polymers into albumin nanoparticles. Recently, several research groups have reported successful desolvation-assisted preparation of protein-coated nanozymes including gold [12], iron [13,14], and cerium nanoparticles [15]. The desolvation method has not been reported for encapsulation of Prussian blue nanozymes. ...
Prussian blue nanozymes exhibit peroxidase-like catalytic activity and are therefore considered a stable and inexpensive alternative to natural peroxidases in the enzyme-linked immunosorbent assay (ELISA). In this work, we propose a robust method of Prussian blue nanozyme functionalization, which relies on the entrapment of nanozymes into albumin nanoparticles. The principle of the method is the addition of ethanol to a solution that contains albumin and nanozymes. At a high ethanol concentration solubility of albumin decreases, resulting in the formation of albumin nanoparticles loaded with nanozymes. The hydrodynamic diameter of nanoparticles was between 120 and 230 nm and depended on the nanozyme-to-BSA ratio. Encapsulation efficiency of nanozymes reached 96–99% and up to 190 μg of nanozymes were loaded per 1 mg of nanoparticles. Nanoparticles were stable at pH 5.5–7.5 and upon long-term storage in deionized water. Excellent reproducibility of the synthesis procedure was confirmed by the preparation of three individual batches of Prussian-blue-loaded BSA nanoparticles with almost identical properties. Nanoparticles were functionalized with monoclonal antibodies using glutaraldehyde cross-linking. The resulting conjugates were applied as labels in an ELISA-like assay of tumor marker prostate-specific antigen (PSA). The lower limit of detection was below 1 ng/mL, which enables measurement of PSA in the range of clinically relevant concentrations.
The development of heterogeneous drug delivery systems leads to innovative strategies for targeted therapy of common pathologies, such as cancer, immunological and neurological disorders. Nowadays, it is possible to choose among a great variety of nanoparticles on the basis of the needs they have to satisfy. However, a candidate for the treatment of cardiovascular pathologies is still missing. In this context, a targeted therapy implies the conceptualization of nanoparticles that take active part in the treatment of vascular pathologies. The aim of this work was to provide a method to produce multi-layered calcium carbonate (CaCO3) nanoparticles encapsulating a model protein, bovine serum albumin, with model antibodies on their surface. CaCO3 nanoparticles were produced by the combination of complex coacervation and mineralization and were engineered using Layer-by-Layer technique with a polysaccharide, dextran sulfate, and a homo-poly-amino acid, poly-L-arginine. Morphology, biocompatibility, cellular uptake, influence on cell expression of the inflammatory marker matrix metalloproteinase-9, and hemocompatibility of the nanoparticles were studied. The presence of the dextran/poly-L-arginine layers did not negatively affect the nanoparticle overall characteristics and they did not trigger proinflammatory response in vitro. Taking together all the obtained results, we consider the proposed CaCO3 nanoparticles as a promising tool in cardiovascular field.
When nanoparticles enter the body, their interactions with cells are almost unavoidable. Unintended nanoparticle interaction with immune cells may elicit a molecular response that can have toxic effects and lead to greater susceptibility to infectious diseases, autoimmune disorders, and cancer development. As evidenced by several studies, nanoparticle interactions with biological systems can stimulate inflammatory or allergic reactions and activate the complement system. Nanoparticles can also stimulate immune response by acting as adjuvants or as haptens. Immunosuppressive effects have also been reported. This article gives a brief review of in vitro and in vivo research evidencing stimulatory or suppressive effects of nanoparticles on the immune system of mammals. In order to ensure safe use of nanosized particles, future research should focus on how their physical and chemical properties influence their behaviour in the biological environment, as they not only greatly affect nanoparticle-immune system interactions but can also interfere with experimental assays.
Magnetic hyperthermia is a fast emerging, non-invasive cancer treatment method which is used synergistically with the existing cancer therapeutics. We have attempted to address the current challenges in clinical magnetic hyperthermia-improved biocompatibility and enhanced heating characteristics, through a single combinatorial approach. Both superparamagnetic iron oxide nanoparticles (SPIONs) of size 10 nm and ferrimagnetic iron oxide nanoparticles (FIONs) of size 30 nm were synthesized by thermal decomposition method for comparison studies. Two different surface modifying agents, viz, Cetyl Trimethyl Ammonium Bromide and 3-Aminopropyltrimethoxysilane, were used to conjugate Bovine Serum Albumin (BSA) over the iron oxide nanoparticles via two different methods—surface charge adsorption and covalent amide bonding, respectively. The preliminary haemolysis and cell viability experiments show that BSA conjugation mitigates the haemolytic effect of the iron oxide nanoparticles on erythrocytes and is non-cytotoxic to the healthy Baby Hamster Kidney cells. It was observed from the results that due to better colloidal stability, the SAR value of the BSA-iron oxide nanoparticles is higher than the iron oxide nanoparticles without BSA, irrespective of the size of the iron oxide nanoparticles and method of conjugation. The BSA-FIONs seem to show improved biocompatibility, as the haemolytic index is less than 2 % and cell viability is up to 120 %, when normalized with the control. The SAR value of BSA-FIONs is 2300 W g−1 when compared to 1700 W g−1 of FIONs without BSA conjugation. Thus, we report here that BSA conjugation over FIONs (with a high saturation magnetization of 87 emu g−1) provide a single combinatorial approach to improve the biocompatibility and enhance the SAR value for magnetic hyperthermia, thus addressing both the current challenges of the same.
Graphical Abstract
Fourier-transform infrared spectra of a synthetic akaganeite, β-FeOOH, were acquired in transmittance, attenuated total reflectance (ATR) and diffuse reflectance. The transmittance spectra showed a distinct dependence on the mode of sample preparation: measurements taken on pellets prepared by pressing the sample with alkali halides (KBr or CsI) displayed bands at 1096, 1050, and 698 cm-1 that were not observed in spectra of the neat material and must therefore be considered artifacts. Variations in the sampling environment (e.g., water and/or organic volatiles) were also observed to exert a noticeable influence on the development of the IR spectra. Infrared bands due to akaganeite were found at 3480 + 3390 (doublet), 1630, 850 + 820 (doublet), 650, 490, and ~420 cm-1. Diffuse reflectance spectra dominated by volume scattering (loose), diffuse reflectance spectra comprised of both volume and surface scattering (compacted), ATR spectra (surface only), and transmittance spectra (absorbance only, inverse of ATR) showed compatible trends for the akaganeite features both above and below ~1000 cm-1. This indicates that the multiple akaganeite measurements are consistent and confirms the band assignments.
When nanoparticles enter the body, their interactions with cells are almost unavoidable. Unintended nanoparticle interaction with immune cells may elicit a molecular response that can have toxic effects and lead to greater susceptibility to infectious diseases, autoimmune disorders, and cancer development. As evidenced by several studies, nanoparticle interactions with biological systems can stimulate inflammatory or allergic reactions and activate the complement system. Nanoparticles can also stimulate immune response by acting as adjuvants or as haptens. Immunosuppressive effects have also been reported. This article gives a brief review of in vitro and in vivo research evidencing stimulatory or suppressive effects of nanoparticles on the immune system of mammals. In order to ensure safe use of nanosized particles, future research should focus on how their physical and chemical properties influence their behaviour in the biological environment, as they not only greatly affect nanoparticle-immune system interactions but can also interfere with experimental assays.
A revolution occurred during the last decade in the comprehension of the physiology as well as in the physiopathology of iron metabolism. The purpose of this review is to summarize the recent knowledge that has accumulated, allowing a better comprehension of the mechanisms implicated in iron homeostasis. Iron metabolism is very fine tuned. The free molecule is very toxic; therefore, complex regulatory mechanisms have been developed in mammalian to insure adequate intestinal absorption, transportation, utilization, and elimination. 'Ironomics' certainly will be the future of the understanding of genes as well as of the protein-protein interactions involved in iron metabolism.
TiO2 nanoparticles (NPs) are contained in different kinds of
industrial products including paints, self-cleaning glasses, sunscreens.
TiO2 is also employed in photocatalysis and it has been
proposed for waste water treatment. Micrometric TiO2 is
generally considered a safe material, while there is concern on the
possible health effects of nanometric titania. Due to their small size
NPs may migrate within the human body possibly entering in the blood
stream. Therefore studies on the interaction of NPs with plasma proteins
are needed. In fact, the interaction with proteins is believed to
ultimately influences the NPs biological fate. Fibrinogen and albumin
are two of the most abundant plasma proteins. They are involved in
several important physiological functions. Furthermore, fibrinogen is
known to trigger platelet adhesion and inflammation. For these reasons
the study of the interaction between these protein and nanoparticles is
an important step toward the understanding of the behavior of NPs in the
body. In this study we investigated the interaction of albumin and
fibrinogen with TiO2 nanoparticles of different crystal
phases (rutile and anatase) using an integrated set of techniques. The
amount of adsorbed fibrinogen and albumin for each TiO2
surface was investigated by using the bicinchoninic acid assay (BCA).
The variation of the surface charge of the NP-protein conjugates respect
to the naked NPs was used to indirectly estimate both surface coverage
and reversibility of the adsorption upon dilution. Surface charge was
monitored by measuring the ζ potential with a conventional
electrophoretic light scattering (ELS) system. The extent of protein
deformation was evaluated by Raman Spectroscopy. We found that both
proteins adsorb irreversibly against electrostatic repulsion, likely
undergoing conformational changes or selective orientation upon
adsorption. The size of primary particles and the particles aggregation
rather than the crystal phase modulate the affinity of fibrinogen for
the TiO2 surfaces.
Background:
Poly lactic-co-glycolic acid (PLGA) based nanoparticles are considered to be a promising drug carrier in tumor targeting but suffer from the high level of opsonization by reticuloendothelial system due to their hydrophobic structure. As a result surface modification of these nanoparticles has been widely studied as an essential step in their development. Among various surface modifications, human serum albumin (HSA) possesses advantages including small size, hydrophilic surface and accumulation in leaky vasculature of tumors through passive targeting and a probable active transport into tumor tissues.
Methods:
PLGA nanoparticles of docetaxel were prepared by emulsification evaporation method and were surface conjugated with human serum albumin. Fourier transform infrared spectrum was used to confirm the conjugation reaction where nuclear magnetic resonance was utilized for conjugation ratio determination. In addition, transmission electron microscopy showed two different contrast media in conjugated nanoparticles. Furthermore, cytotoxicity of free docetaxel, unconjugated and conjugated PLGA nanoparticles was studied in HepG2 cells.
Results:
Size, zeta potential and drug loading of PLGA nanoparticles were about 199 nm, -11.07 mV, and 4%, respectively where size, zeta potential and drug loading of conjugated nanoparticles were found to be 204 nm, -5.6 mV and 3.6% respectively. Conjugated nanoparticles represented a three-phasic release pattern with a 20% burst effect for docetaxel on the first day. Cytotoxicity experiment showed that the IC50 of HSA conjugated PLGA nanoparticles (5.4 μg) was significantly lower than both free docetaxel (20.2 μg) and unconjugated PLGA nanoparticles (6.2 μg).
Conclusion:
In conclusion surface modification of PLGA nanoparticles through HSA conjugation results in more cytotoxicity against tumor cell lines compared with free docetaxel and unconjugated PLGA nanoparticles. Albumin conjugated PLGA nanoparticles may represent a promising drug delivery system in cancer therapy.
As revealed by electron microscopy and electron diffraction, the physical state of ferric hydroxide micelles contained in
iron-dextran, saccharated iron oxide, and hydrous ferric oxide ("ferric hydroxide") differs notably from the state of the
ferric hydroxide in ferritin or hemosiderin. By virtue of this difference one can trace the intracellular transformation of
colloidal iron, administered parenterally, into ferritin and hemosiderin.
One hour after intraperitoneal injection of iron-dextran or saccharated iron oxide into mice, characteristic deposits were
present in splenic macrophages, in sinusoidal endothelial cells of spleen and liver, and in vascular endothelial cells of
various renal capillaries. Four hours after injection, small numbers of ferritin molecules were identifiable about intracellular
aggregates of injected iron compounds; and by the 6th day, ferritin was abundant in close proximity to deposits of injected
iron compounds. The latter were frequently situated in cytoplasmic vesicles delimited by single membranes. These vesicles
were most frequently found in tissue obtained during the first 6 days after injection; and in certain of the vesicles ferritin
molecules surrounded closely packed aggregates of injected material. Much unchanged ferric hydroxide was still present in
macrophages and vascular endothelial cells 3 to 4 weeks after injection.
While electron microscopy left no doubt about the identity of injected ferric hydroxide on the one hand, and of ferritin or
hemosiderin on the other, histochemical tests for iron failed in this respect.
Precipitation of ferric hydroxide (hydrous ferric oxide) from stabilized colloidal dispersions of iron-dextran was brought
about in vitro by incubation with minced mouse tissue (e.g. liver), but not by incubation with mouse serum or blood.
Subcutaneous injections of hydrous gel of ferric oxide into mice initially produced localized extracellular precipitates.
Most of the material was still extracellular 16 days after injection, though part of it was phagocytized by macrophages near
the site of injection; but apparently none reached the spleen in unaltered form. Five days after injection and thereafter,
much ferritin was present in macrophages about the site of injection and in the spleen.
The findings show that iron preparations widely used in therapy can be identified within cells, and that their intracellular
disposition and fate can be followed at the molecular level. Considered in the light of previous work, they indicate that
the characteristic structure of the ferric hydroxide micelles in molecules of ferritin is specific, and develops during the
union of apoferritin with ferric hydroxide. Apparently this union does not depend upon specific cell components.
Oral iron supplementation is usually the first choice for the treatment of iron deficiency anemia (IDA) because of its effectiveness and low cost. But unfortunately in many iron deficient conditions, oral iron is a less than the ideal treatment mainly because of adverse events related to the gastrointestinal tract as well as the long course required to treat anemia and replenish body iron stores. The first iron product for intravenous use was high-molecular-weight iron dextran. However, dextran-containing intravenous iron preparations are associated with an elevated risk of anaphylactic reactions, which made physicians reluctant to prescribe intravenous iron in the treatment of iron deficiency anemia for many years. In 1999 and 2001, two new intravenous iron preparations (ferric gluconate and iron sucrose) were introduced into the market as safer alternatives to iron dextran. Over the last five years, three new intravenous iron dextran-free preparations have been developed and have better safety profiles than the more traditional intravenous compounds, as none require test doses and all these products are promising in respect to a more rapid replacement of body iron stores (15-60 minutes/infusion) as they can be given at higher doses (from 500 mg to more than 1000 mg/infusion). The purpose of this review is to discuss some pertinent issues in relation to the history, pharmacology, administration, efficacy, safety profile and toxicity of intravenous iron for the treatment of iron deficiency anemia.
Iron is an essential but potentially hazardous biometal. Mammalian cells require sufficient amounts of iron to satisfy metabolic needs or to accomplish specialized functions. Iron is delivered to tissues by circulating transferrin, a transporter that captures iron released into the plasma mainly from intestinal enterocytes or reticuloendothelial macrophages. The binding of iron-laden transferrin to the cell-surface transferrin receptor 1 results in endocytosis and uptake of the metal cargo. Internalized iron is transported to mitochondria for the synthesis of haem or iron-sulfur clusters, which are integral parts of several metalloproteins, and excess iron is stored and detoxified in cytosolic ferritin. Iron metabolism is controlled at different levels and by diverse mechanisms. The present review summarizes basic concepts of iron transport, use and storage and focuses on the IRE (iron-responsive element)/IRP (iron-regulatory protein) system, a well known post-transcriptional regulatory circuit that not only maintains iron homoeostasis in various cell types, but also contributes to systemic iron balance.
Nanoparticles in contact with biological fluids interact with proteins and other biomolecules, thus forming a dynamic corona whose composition varies over time due to continuous protein association and dissociation events. Eventually equilibrium is reached, at which point the continued exchange will not affect the composition of the corona.
We developed a simple and effective dynamic model of the nanoparticle protein corona in a body fluid, namely human plasma. The model predicts the time evolution and equilibrium composition of the corona based on affinities, stoichiometries and rate constants. An application to the interaction of human serum albumin, high density lipoprotein (HDL) and fibrinogen with 70 nm N-iso-propylacrylamide/N-tert-butylacrylamide copolymer nanoparticles is presented, including novel experimental data for HDL.
The simple model presented here can easily be modified to mimic the interaction of the nanoparticle protein corona with a novel biological fluid or compartment once new data will be available, thus opening novel applications in nanotoxicity and nanomedicine.
The pharmacokinetics of a single intravenous injection of 100 mg iron hydroxide-sucrose complex labelled with a tracer in the form of 52Fe/59Fe was followed in six anaemic patients for a period ranging from 6 to 8 3 h using positron emission tomography (PET). Red cell utilization of the labelled iron was followed for 4 weeks. PET data showed radioactive uptake by the liver, spleen and bone marrow. The uptake by the macrophage-rich spleen demonstrated the reticuloendothelial uptake of this iron preparation, with subsequent effective release of that iron for marrow utilization. Red cell utilization, followed for 4 weeks, ranged from 59% to 97%. The bone marrow influx rate constant was independent of blood iron concentration, indicating non-saturation of the transport system in bone marrow. This implied that higher doses of the iron complex can probably be used in the same setting. A higher influx rate into the marrow compared with the liver seemed to be consistent with higher red cell utilization. This would indicate that early distribution of the injected iron complex may predict the long-term utilization.
The human plasma proteome holds the promise of a revolution in disease diagnosis and therapeutic monitoring provided that major challenges in proteomics and related disciplines can be addressed. Plasma is not only the primary clinical specimen but also represents the largest and deepest version of the human proteome present in any sample: in addition to the classical "plasma proteins," it contains all tissue proteins (as leakage markers) plus very numerous distinct immunoglobulin sequences, and it has an extraordinary dynamic range in that more than 10 orders of magnitude in concentration separate albumin and the rarest proteins now measured clinically. Although the restricted dynamic range of conventional proteomic technology (two-dimensional gels and mass spectrometry) has limited its contribution to the list of 289 proteins (tabulated here) that have been reported in plasma to date, very recent advances in multidimensional survey techniques promise at least double this number in the near future. Abundant scientific evidence, from proteomics and other disciplines, suggests that among these are proteins whose abundances and structures change in ways indicative of many, if not most, human diseases. Nevertheless, only a handful of proteins are currently used in routine clinical diagnosis, and the rate of introduction of new protein tests approved by the United States Food and Drug Administration (FDA) has paradoxically declined over the last decade to less than one new protein diagnostic marker per year. We speculate on the reasons behind this large discrepancy between the expectations arising from proteomics and the realities of clinical diagnostics and suggest approaches by which protein-disease associations may be more effectively translated into diagnostic tools in the future.
The surface characteristics of intravenously administered particulate drug carriers decisively influence the protein adsorption that is regarded as a key factor for the in vivo fate of the carriers. Latex nanoparticles were synthesized to study the influence of different basic and acidic functional groups on particulate surfaces on the protein adsorption from human serum. The protein mass adsorbed to the particles was assessed by BCA protein assay, the protein adsorption patterns were analyzed by two-dimensional electrophoresis. Considerable differences in the protein adsorption with regard to preferential adsorbed proteins were detectable for the different functional groups. Possible correlations between the surface characteristics and the protein adsorption are shown and discussed. The knowledge concerning the interactions of proteins and nanoparticles can be used for a rational development of particulate drug carriers and can also be useful for an optimized design of medical devices, e.g., hemodialysis membranes or implants.
Magnetic nanoparticles have been used for biomedical purposes for several years. In recent years, nanotechnology has developed to a stage that makes it possible to engineer particles to provide opportunities for the site-specific delivery of drugs. To this end a variety of iron oxide particles have been synthesised. The size and surface of the particles are crucial factors in the application of the particles. This study therefore involves the use of magnetic nanoparticles synthesised and derivatised with either dextran or albumin, compared to identical underivatised plain particles. This influence in vitro was assessed using human dermal fibroblasts and various techniques to observe cell-particles interaction, including light and fluorescence microscopy, scanning and transmission electron microscopy. The results indicate that the derivatised particles induce alterations in cell behaviour and morphology distinct from the plain particles, suggesting that cell response can be directed via specifically engineered particle surfaces.
As revealed by electron microscopy and electron diffraction, the physical state of ferric hydroxide micelles contained in iron-dextran, saccharated iron oxide, and hydrous ferric oxide ("ferric hydroxide") differs notably from the state of the ferric hydroxide in ferritin or hemosiderin. By virtue of this difference one can trace the intracellular transformation of colloidal iron, administered parenterally, into ferritin and hemosiderin. One hour after intraperitoneal injection of iron-dextran or saccharated iron oxide into mice, characteristic deposits were present in splenic macrophages, in sinusoidal endothelial cells of spleen and liver, and in vascular endothelial cells of various renal capillaries. Four hours after injection, small numbers of ferritin molecules were identifiable about intracellular aggregates of injected iron compounds; and by the 6th day, ferritin was abundant in close proximity to deposits of injected iron compounds. The latter were frequently situated in cytoplasmic vesicles delimited by single membranes. These vesicles were most frequently found in tissue obtained during the first 6 days after injection; and in certain of the vesicles ferritin molecules surrounded closely packed aggregates of injected material. Much unchanged ferric hydroxide was still present in macrophages and vascular endothelial cells 3 to 4 weeks after injection. While electron microscopy left no doubt about the identity of injected ferric hydroxide on the one hand, and of ferritin or hemosiderin on the other, histochemical tests for iron failed in this respect. Precipitation of ferric hydroxide (hydrous ferric oxide) from stabilized colloidal dispersions of iron-dextran was brought about in vitro by incubation with minced mouse tissue (e.g. liver), but not by incubation with mouse serum or blood. Subcutaneous injections of hydrous gel of ferric oxide into mice initially produced localized extracellular precipitates. Most of the material was still extracellular 16 days after injection, though part of it was phagocytized by macrophages near the site of injection; but apparently none reached the spleen in unaltered form. Five days after injection and thereafter, much ferritin was present in macrophages about the site of injection and in the spleen. The findings show that iron preparations widely used in therapy can be identified within cells, and that their intracellular disposition and fate can be followed at the molecular level. Considered in the light of previous work, they indicate that the characteristic structure of the ferric hydroxide micelles in molecules of ferritin is specific, and develops during the union of apoferritin with ferric hydroxide. Apparently this union does not depend upon specific cell components.
Drug products containing iron oxide and hydroxide nanoparticles (INPs) are important for the treatment of iron deficiency anaemia. Pharmaceuticals prepared by the complexation of different kinds of INPs and carbohydrates have different physicochemical and biopharmaceutic characteristics. The increasing number of parenteral non-biological complex drugs (NBCD) containing iron requires physicochemical methods for characterization and enabling of cross comparisons. In this context the structure and the level of crystallinity of the iron phases may be connected to the in vitro and in vivo dissolution rates, which etiologically determine the therapeutic and toxic effects.
Most research on the toxicology of nanomaterials has focused on the effects of nanoparticles that enter the body accidentally. There has been much less research on the toxicology of nanoparticles that are used for biomedical applications, such as drug delivery or imaging, in which the nanoparticles are deliberately placed in the body. Moreover, there are no harmonized standards for assessing the toxicity of nanoparticles to the immune system (immunotoxicity). Here we review recent research on immunotoxicity, along with data on a range of nanotechnology-based drugs that are at different stages in the approval process. Research shows that nanoparticles can stimulate and/or suppress the immune responses, and that their compatibility with the immune system is largely determined by their surface chemistry. Modifying these factors can signifi cantly reduce the immunotoxicity of nanoparticles and make them useful platforms for drug delivery. © 2010 Nature Publishing Group, a division of Macmillan Publishers Limited and published by World Scientific Publishing Co. under licence. All Rights Reserved.
We prepared the in situ formed iron hydroxide (In situ FeOxHy) by the interactions between Fe3+ and OH- at different molar ratios of 1:0, 1:1, 1:2, and 1:3, and investigated the performance and mechanism involved in the removal of phosphate. The removal efficiency increased with elevated doses of FeOxHy and the maximum removal was observed to be in neutral pH ranges. The elevated ratios of OH- to Fe3+ inhibit the removal of phosphate whereas at low alkalinity, the introduction of OH- shows beneficial effects. The abovementioned four kinds of FeOxHy can rapidly adsorb most phosphate within 15 s, and the adsorption process can be well described by the Pseudo-second-order kinetic model. Freundlich model can well describe the adsorption of phosphorus onto these four FeOxHy. The adsorption of phosphate significantly decreases the zeta potential of these in situ FeOxHy. The MINITEQ software can indicate the species distribution of phosphate and iron salts, and the theoretical calculation indicates that the introduced OH- can promote the hydrolysis of Fe3+ especially in low alkalinity system, which can easily adsorb H2PO4- and HPO42- and form the multinuclear hydroxy iron phosphate complexes thereafter.
Nanoparticles are being increasingly implemented in drug delivery and diagnostic systems, as they show promising features in protected, targeted and sustained delivery of active pharmaceutical ingredients and contrast agents. Following intravenous injection, nanoparticles, depending on their physicochemical properties, may trigger the complement system, which is a major part of the innate immune system. Complement activation and fixation can prime the surface of nanoparticles for rapid recognition and clearance by complement receptor bearing cells such as blood monocytes and macrophages of the reticuloendothelial system. Uncontrolled complement activation can also induce adverse reactions, and these have been reported with regulatory approved nanomedicines, including stealth therapeutics. We discuss on the interaction between the complement system and synthetic surfaces, and comment on general physicochemical parameters that incite complement. State-of-the-art approaches for evaluation and determination of complement activation and sensing are also described.
With a view to achieve stable the ultrafine akaganeite (β-FeO(OH)) particles, they are synthesized by varying the molar concentration of dextrose, x = 0.2, 0.4, 0.6, 0.8, 1.0M, as chelating agent in co–precipitation method. The struc-tural properties studied using the powder X–ray diffraction patterns show that an optimum concentration of dextrose for the formation of akaganeite is 0.6M. The particles possess tetragonal crystal structures and the size of grains is in the order of nanometer (~18 to 29nm). DSC curves explain the chemical reactions and phase transitions undergone by the sample. FT-IR spectra of the nanoparticles of akaganeite show the absorption bands at 491 and 445cm -1 in all the samples corres-ponding to the symmetric stretching vibrations of Fe-O bond and its ligands respectively in the octahedral co-ordinations. UV–Visible spectra of the present set of samples clearly exhibit a change in the optical bandgap from 1.97 to 2.14eV. The magnetic studies could bring out a weak ferrimagnetic behaviour accompanied by superparamagnetism in the akaganeite nanoparticles.
Abstract Progress has been made in using human serum albumin nanoparticles (HSAPs) as promising colloidal carrier systems for early detection and targeted treatment of cancer and other diseases. Despite this success, there is a current lack of multi-functional HSAP hybrids that offer combinational therapies. The size of the HSAPs has crucial importance on drug loading and in vivo performance and has previously been controlled via manipulation of pH and cross-linking parameters. Gold nanomaterials have also gained attention for medicinal use due to their ability to absorb near-infrared light, thus offering photothermal capabilities. In this study, the desolvation and cross-linking approach was employed to encapsulate gold nanorods, nanoparticles, and nanoshells into HSAPs. Incorporation of gold nanomaterials caused some changes in HSAP sizes, but the general size trends remained. This encasement strategy facilitated size-controlled HSAPs, in the range of 100-300 nm, loaded with gold nanostructures; providing composite particles which incorporate photothermally active components.
The products of boiling hydrolysis of ferric chloride solutions have been compared with well-known iron oxide phases by the use of i.r. and Mössbauer spectroscopy, electron microscopy, and chemical reactivity. The product of boiling dilute solutions for a short duration was very similar to the well-known amorphous gel. It appeared to be structurally a mixed phase similar to α-FeOOH and β-FeOOH. Increasing the duration of boiling and the concentration of solutions yielded products which were identified as poorly crystalline α-Fe2O3 and α-FeOOH.
A new mesoporous form of crystalline β-FeOOH (akaganeite) was successfully prepared by a technology of surfactant-assisted nanoparticle assembly in the presence of a nonionic PEO-surfactant. The synthesized mesoporous β-FeOOH has a high surface area of 228 m2/g and a pore size of 4.3 nm with a hierarchical scaffold-like structure formed through the aggregation and intergrowth of akaganeite nano-rods. To our knowledge, this is first known report of mesostructured crystalline akaganeite material. Thermal treatment at 200 °C afforded the retention of the akaganeite structure. A complete transformation to hematite occurred after calcination at 300 °C with structural collapse.
We have studied the interaction of macromolecular anticancer agent SMANCS, a conjugate of partially half-butyl-esterified styrene-co-maleic acid polymer[butyl-SMA]- and neocarzinostatin (NCS), with various serum proteins by the fluorescence polarization method. Comparatively strong binding of FITC-labeled SMANCS (F-SMANCS) to human serum albumin (HSA) and weak binding to fibrinogen were observed, while other serum proteins did not exhibit any appreciable binding profile. From Scatchard polt analysis, the asso ciation constant of binding for F-SMANCS to HSA at 37 °C, pH 7.4 was calculated to be 2.19 × 106 M-1 and the number of moles of F-SMANCS bound to 1 mol of HSA was 3.2 Binding of F-NCS to HSA was not observed. The F-SMANCS bound to HSA was effectively displaced by butyl-SMA, but not by NCS. This evidence supports that SMANCS binds to HSA through butyl-SMA, not through NCS portion. A role of the alkyl ester groups of SMA derivatives to HSA binding was investigated by competitive inhibition using butyl-SMA, ethyl-SMA, H-SMA and short chain butyl-SMA. The degree of competitive in hibition was stronger in the following order: butyl-(n = 6) > ethyl (n = 6) = short butyl-(n = 4) > H-SMA. The number of carbons introduced by esterification and the hydrophobicity of SMA derivatives both positively in fluence the binding affinity to HSA. The binding site for SMANCS on HSA was investigated. From the competitive inhibition of known standard drugs (war farin, diazepam and digitoxin) and endogenous substance (bilirubin) in the albumin binding. The binding site on HSA appears to be in the close vicinity to the warfarin or diazepam binding site, and might partially overlap with the bilirubin binding site. These data support that the prolonged plasma half-life of SMANCS in vivo reported previously can be attributed to this albumin binding.
Nanoparticle interactions with the blood coagulation system can be beneficial or adverse depending on the intended use of a nanomaterial. Nanoparticles can be engineered to be procoagulant or to carry coagulation-initiating factors to treat certain disorders. Likewise, they can be designed to be anticoagulant or to carry anticoagulant drugs to intervene in other pathological conditions in which coagulation is a concern. An overview of the coagulation system was given and a discussion of a desirable interface between this system and engineered nanomaterials was assessed in part I, which was published in the May 2013 issue of Nanomedicine. Unwanted pro- and anti-coagulant properties of nanoparticles represent significant concerns in the field of nanomedicine, and often hamper the development and transition into the clinic of many promising engineered nanocarriers. This part will focus on the undesirable effects of engineered nanomaterials on the blood coagulation system. We will discuss the relationship between the physicochemical properties of nanoparticles (e.g., size, charge and hydrophobicity) that determine their negative effects on the blood coagulation system in order to understand how manipulation of these properties can help to overcome unwanted side effects.
The adsorption behaviors of three proteins, human serum albumin, β-lactoglobulin and β-casein, respectively, at the chloroform/water interface were studied by using the pendent drop technique. A drop was produced by immersing the pure chloroform solvent into protein buffer solution through a quartz capillary. It has been found that a folded drop surface can be formed by the adsorption of each protein after certain time. The ‘skin-like’ film was assumed to be composed of adsorption layer of protein. By using a 50 μm capillary, we have obtained a hundreds of micrometer droplet. The adsorption kinetics of each protein was recorded by using the commercial software of axisymmetric drop shape analysis to understand the forming process of the ‘skin-like’ film.
Biogenic microcapsules comprised of l-α-dimyristoyl phosphatitic acid (DMPA)/human serum albumin (HSA) were prepared by stepwise adsorption of DMPA/HSA multilayers onto charged colloids and subsequent dissolution of the colloidal cores. The properties of both lipid/protein modified particles and the hollow capsules were characterized by microelectrophoresis, scanning electron microscopy, transmission electron microscopy, confocal laser scanning microscopy, and scanning force microscopy, respectively. Single particle light scattering together with small-angle X-ray scattering measurements revealed that DMPA forms a bilayer structure on the HSA surface. A combination of HSA and DMPA on hollow capsules is proposed as a biomimetic membrane model.
Iron metabolism in man is a highly regulated process designed to provide iron for erythropoiesis, mitochondrial energy production, electron transport, and cell proliferation. The mechanisms of iron handling also protect cells from the deleterious effects of free iron, which can produce oxidative damage of membranes, proteins, and lipids. Over the past decade, several important molecules involved in iron homeostasis have been discovered, and their function has expanded our understanding of iron trafficking under normal and pathological conditions. Physiologic iron metabolism is strongly influenced by inflammation, which clinically leads to anemia. Although hepcidin, a small circulating peptide produced by the liver, has been found to be the key regulator of iron trafficking, molecular pathways of iron sensing that control iron metabolism and hepcidin production are still incompletely understood. With this review, we provide an overview of the current understanding of iron metabolism, the recently discovered regulators of iron trafficking, and a focus on the effects of inflammation on the process.
The size effect of nanomaterials is of major interest, since it may affect their bioavailability and toxicity. In this study, bovine serum albumin (BSA) nanoparticles were prepared using a modified desolvation method. Bare BSA nanoparticles and calcium (Ca)-loaded BSA nanoparticles were fabricated at the targeted sizes, 100, 400, and 800 nm. The mean diameters of the prepared BSA nanoparticles were 125, 393, and 713 nm; those of the Ca-BSA nanoparticles were 260, 353, and 919 nm. The surface-area-to-volume-ratios of the prepared BSA nanoparticles were 4.82, 1.53, and 1.03 nm−1; those of the Ca-BSA nanoparticles were 2.34, 1.72, and 0.90 nm−1. The size and the surface-area-to-volume-ratio of the BSA nanoparticles were controlled by adjusting BSA concentration, pH, and NaCl content, which affected the coagulation of the BSA molecules. The surface-area-to-volume-ratio is a more useful parameter than the mean diameter of particles for comparing effectiveness of nanoparticles.Research highlights► Nanoparticles of a controlled size are important to ascertain size effect in food. ► Difference in manufacturing processes affects particle properties. ► Different-size similar-surface particles are good tools to study size effect. ► Size-controlled BSA nanoparticles are prepared by similar manufacturing processes. ► Size-controlled BSA nanoparticles prepared are useful as standard materials.
The concentration dependence of surface tension was evaluated with DuNoüy ring tensiometry for solutions of α-lactalbumin (α-Lac), β-lactoglobulin (β-Lg), and bovine serum albumin (BSA). Surface tension kinetics were measured as well and interpreted in terms of first-order rate constants defining adsorption and interfacial rearrangement. Although molecularly dissimilar in several ways, the surface activity of each protein could be explained with reference to its relative flexibility and stability. Molecular size seemed to be an important factor governing incorporation of protein into an interfacial layer. α-Lac, the smallest and least stable protein, was observed to be the most surface active. BSA is the largest molecule and consists of three large domains and nine subdomains. Its surface activity is consistent with the thought that it is largely governed by the behavior of one of these domains and its activity after adsorption. β-Lg is roughly half the size of BSA and apparently adsorbs faster than BSA, but exhibited a similar equilibrium II behavior. This is attributed to its dimer structure and the presence of a free thiol in each monomeric subunit capable of facilitating thiol—disulfide interchange reactions, probably causing it to be less flexible than BSA.
Proteins bind the surfaces of nanoparticles, and biological materials in general, immediately upon introduction of the materials into a physiological environment. The further biological response of the body is influenced by the nanoparticle–protein complex. The nanoparticle's composition and surface chemistry dictate the extent and specificity of protein binding. Protein binding is one of the key elements that affects biodistribution of the nanoparticles throughout the body. Here we review recent research on nanoparticle physicochemical properties important for protein binding, techniques for isolation and identification of nanoparticle-bound proteins, and how these proteins can influence particle biodistribution and biocompatibility. Understanding the nanoparticle–protein complex is necessary for control and manipulation of protein binding, and allows for improved engineering of nanoparticles with favorable bioavailability and biodistribution.
The key role of protein-nanoparticle interactions in nanomedicine and nanotoxicity has begun to emerge recently with the development of the idea of the nanoparticle-protein ‘corona’. This dynamic layer of proteins (and other biomolecules) adsorbs to nanoparticle surfaces immediately upon contact with living systems. While within the biomaterials field the role of adsorbed molecules in cellular responses is acknowledged, there are several new issues at stake where nanoparticles are concerned. We show here that highly selective protein adsorption, added to the fact that particles can reach subcellular locations, results in significant new potential impacts for nanoparticles on protein interactions and cellular behavior.
Albumin, a versatile protein carrier for drug delivery, has been shown to be nontoxic, non-immunogenic, biocompatible and biodegradable. Therefore, it is ideal material to fabricate nanoparticles for drug delivery. Albumin nanoparticles have gained considerable attention owing to their high binding capacity of various drugs and being well tolerated without any serious side-effects. The current review embodies an in-depth discussion of albumin nanoparticles with respect to types, formulation aspects, major outcomes of in vitro and in vivo investigations as well as site-specific drug targeting using various ligands modifying the surface of albumin nanoparticles with special insights to the field of oncology. Specialized nanotechnological techniques like desolvation, emulsification, thermal gelation and recently nano-spray drying, nab-technology and self-assembly that have been investigated for fabrication of albumin nanoparticles, are also discussed. Nanocomplexes of albumin with other components in the area of drug delivery are also included in this review.
Iron has the capacity to accept and donate electrons readily, interconverting between ferric (Fe2+) and ferrous (Fe3+) forms. This capability makes it a useful component of cytochromes, oxygen-binding molecules (i.e., hemoglobin and myoglobin), and many enzymes. However, iron can also damage tissues by catalyzing the conversion of hydrogen peroxide to free-radical ions that attack cellular membranes, proteins, and DNA. Proteins sequester iron to reduce this threat. Iron ions circulate bound to plasma transferrin and accumulate within cells in the form of ferritin. Iron protoporphyrin (heme) and iron–sulfur clusters serve as enzyme cofactors. Under normal circumstances, only trace amounts . . .
Biodegradable micro/nanoparticles generated from PLGA have recently attracted attention due to their clinically proven biocompatibility, especially for immunization purposes. These polymeric particulate delivery systems are able to present antigens and activate both humoral and cellular responses. Many studies have discussed the ideal size of these particles in contributing to the generation of the different types of immune response. However, these studies do not demonstrate the effect of micro or nanoparticles, without any encapsulated bioactive, on phagocytic cells after the uptake process. In this context, the aim of this study was to analyze the in vitro inflammatory behavior of J774 murine macrophages after particles' uptake, since nano/microparticles per se can differently activate phagocytic cells, using or not appropriate receptors, inducing distinct inflammatory responses. An o/w emulsion solvent extraction-evaporation method was chosen to prepare the particles. We determined their diameters, zeta potential and morphology. Fluorescent particles' uptake by J774 murine "macrophage-like" cells was also analyzed. To evaluate the in vitro inflammatory profile of these cells after micro or nanoparticles' uptake, we conducted NF-κB translocation assay by confocal microscopy and also determined the pro-inflammatory cytokines production provoked by the particles.
Protein adsorption at solid surfaces plays a key role in many natural processes and has therefore promoted a widespread interest in many research areas. Despite considerable progress in this field there are still widely differing and even contradictive opinions on how to
explain the frequently observed phenomena such as structural rearrangements, cooperative adsorption, overshooting adsorption kinetics, or protein aggregation. In this review recent achievements and new perspectives on protein adsorption processes are comprehensively
discussed. The main focus is put on commonly postulated mechanistic aspects and their translation into mathematical concepts and model descriptions. Relevant experimental and
computational strategies to practically approach the field of protein adsorption mechanisms and their impact on current successes are outlined.
At the moment two competing explanations exist for the experimental finding that net negatively charged proteins adsorb on or absorb in negatively charged polyelectrolyte brushes. One explanation is based on the possibility of charge regulation. The idea is that a protein can reverse its charge when it is in the presence of the high electrostatic potential of the brush and then can be inserted. The other explanation relies on the charge anisotropy of proteins, that is, that it carries positively charged and negatively charged patches. The positively charged region gains more energy from interacting with the negative brush than the negative charged patch loses, especially when the charge densities and electrostatic potentials are high, thus providing a net attraction. We present a model in which both mechanisms are combined. We confirm that both charge anisotropy and charge regulation effects on their own can be responsible for protein uptake at the "wrong" side of the isoelectric point (IEP). In addition, we find that the respective effects are additive. Indeed, taking both effects into account results in a stronger attraction between a PE brush and protein at the IEP, and the attraction is found further above the IEP than the individual effects would have made possible. Still, for patchiness to have a strong contribution, the patches need very high charge densities. Therefore, we argue that for most types of protein charge reversal will be the main driving force for adsorption on the wrong side of the IEP, while patchiness will contribute less.
To evaluate the evidence for iron compounds as local carcinogens in man, histological material and clinical reports have been reviewed in seven of the eight published cases of tumours developing at the site of intramuscular injections. The microscopical appearances suggested benign lesions in two cases and a variety of tumours in the other five. In only two cases (a rhabdomyosarcoma and a fibrosarcoma) was the interval between injections and tumour development longer than six years. Of the remaining three tumours, one was considered to be a rather slowly growing haemangiopericytoma (with an interval of two years), one appeared to be a subcutaneous lymphoma with no evidence of having arisen in the gluteal muscles, and one was a pleomorphic sarcoma with a possible five-year interval. Sarcomas induced experimentally by iron compounds differ in being less variable in type and in containing abundant iron-containing macrophages, which were negligible in these human tumours.
Although the total number of patients who have received intramuscular injections of iron compounds is not known, the present findings, in contrast to experimental work, do not support the view that such treatment carries a strong risk of tumour development.
Two cases are presented of sarcomata arising at the site of previous iron dextran injections. One of the tumours showed a histological pattern associated with iron dextran administration in animal experiments.
The distribution in various organs and tissues of the rat at different times, of i.v. injected ferric hydroxide, Fe-EDTA, Fe-fructose complex and Fe-albumin labeled with 59Fe has been studied. Fe-EDTA and Fe-fructose complex are readily excreted. On the contrary ferric hydroxide and Pe-albumin remain m liver, spleen, bone and blood cells. After 24 hr, the Fe-albumin radioactivity in the organism has a little change throughout the whole experiment.
Biologically active compounds were entrapped in cross-linked serum albumin microbeads. Injection of these drug-impregnated
beads into rabbits produced no adverse immunological reactions. Sustained release (20 days) of progesterone was demonstrated
in vivo.
Human serum albumin (HSA) nanospheres of about 100 nm diameter were prepared using a pH-coacervation method whereby acetone was added to an HSA solution (pH 9.0). The particles obtained were cross-linked by glutaraldehyde. Increasing the pH of the HSA solution resulted in a gradual rise in the particle size of the resultant nanospheres. A higher cross-linking efficiency was obtained with increased glutaraldehyde concentration and cross-linking time. No significant differences in surface properties, as determined by zeta potential measurements, were recorded between particles prepared from HSA solutions with different pH. The nanospheres were quite stable over 4 days in both phosphate buffer saline (PBS) solution (pH 7.4) and rat serum, but degraded rapidly over 6 hours when incubated in PBS solution containing trypsin.
Small-angle X-ray scattering (SAXS) was used to study structural characteristics of human serum albumin (HSA) in solution under different pH conditions. Guinier analysis of SAXS results yielded values of the molecular radius of gyration ranging from 26.7 A to 34.5 A for pH varying from 2.5 to 7.0. This suggests the existence of significant differences in the overall shape of the molecule at different pH. Molecular models based on subdomains with different spatial configurations were proposed. The distance distribution functions associated with these models were calculated and compared with those determined from the experimental SAXS intensity functions. The conclusion of this SAXS study is that the arrangement of molecular subdomains is clearly pH dependent; the molecule adopting more or less compact configuration for different pH conditions. The conclusions of this systematic study on the modification in molecular shape of HSA as a response to pH changes is consistent with those of previous investigations performed for particular pH conditions.
Our current understanding of sepsis and multiple organ dysfunction needs to be revised, as the uniformly negative results of new therapies for these disorders suggest. Previous theories for the pathogenesis of these conditions are incomplete; reasons for this include the following. First, the surrogate models that have been used to study these disorders are not analogous to the clinical situation. Second, patients who have less severe manifestations of these diseases are often overlooked. And third, patients' preexisting conditions have not been taken into account. Considerable new evidence indicates that, in addition to a massive proinflammatory reaction, a compensatory anti-inflammatory response contributes to the onset of these disorders. At a local site of injury or infection and during the initial appearance of pro- and anti-inflammatory mediators in the circulation, the beneficial effects of these mediators outweigh their harmful effects. Only when the balance between these two forces is lost do these mediators become harmful. Sequelae of an unbalanced systemic proinflammatory reaction include shock, transudation into organs, and defects in coagulation. An unbalanced systemic compensatory anti-inflammatory response can result in anergy and immunosuppression. The proinflammatory and anti-inflammatory forces may ultimately reinforce each other, creating a state of increasingly destructive immunologic dissonance.
The immunopotentiating activities of colloidal iron hydroxide, a novel, experimental mineral adjuvant, and of aluminium hydroxide. the licensed adjuvant for human vaccines, were compared. Our studies revealed that colloidal iron hydroxide and aluminium hydroxide behaved comparably with respect to supporting induction of an antibody response to tetanus toxoid. Furthermore, mice immunized with both, the experimental vaccine (tick-borne encephalitis virus (TBEV) antigen adsorbed to colloidal iron hydroxide) or with a commercially available TBEV vaccine (adjuvanted with aluminium hydroxide), developed long-lasting antibody responses which protected the animals from TBEV infection even one year after vaccination. The use of colloidal iron hydroxide as adjuvant had the additional advantage to reproducibly support induction of HIV-1 envelope-specific cytotoxic T lymphocytes (CTL), when used as adjuvant for a HIV-1 env-carrying recombinant fowlpox virus and being applied via the subcutaneous route. Aluminium hydroxide was much less active in this respect. Non-adjuvanted recombinant fowlpox elicited CTLs only when given intravenously or intraperitoneally, vaccination routes considered not to be suitable for routine use in humans. Further studies to evaluate the use of colloidal iron as possible alternative and/or supplement for routinely used mineral adjuvants may therefore be warranted.
The results of preliminary infrared (IR) spectrometry experiments on bovine serum albumin (BSA) films are presented. An analysis of spectral variations due to raising the temperature and deuteration of N--H groups leads to the assignment of most IR bands of BSA. From this analysis we furthermore deduce that at 115 degrees C only hydrogen bonds established by N&bond;H groups on the still present H(2)O molecules, which are so strongly bound to the protein that they do not evaporate, are weakened, some of which are broken. These N--H...OH(2) groups represent some 5% of all N--H groups in the dried protein. Spectral changes due to hydration by water vapor are also analyzed and a precise method to measure the water-vapor pressure of the atmosphere surrounding the BSA film, or equivalently the relative humidity, is described. Various procedures to measure the number of H(2)O molecules embedded in BSA are then presented and evaluated. One of them is selected as the best one for proteins, because it matches previous measurements based on gravimetric methods. This procedure is subsequently used in a study that is devoted to the determination of the various hydrogen-bond configurations, or interaction configurations, which are adopted by H(2)O molecules during the various steps of hydration of BSA. This first analysis of hydration spectra allows the completion of the assignment of IR bands. The various spectral components of the amide I band, which are interchanged during the hydration process, cannot be assigned to various secondary structures, as is usually proposed. It suggests that this usual assignment should be used with care, especially by taking into account the state of hydration, when one wishes to obtain structural information from it.
Human serum albumin (HSA) and L-alpha-dimyristoylphosphatidic acid (DMPA) were applied as a pair to encapsulate ibuprofen microcrystals by means of a technique based on the layer-by-layer (LbL) assembly of oppositely charged species, for the purpose of controlling drug release. The successful adsorption of HSA and DMPA multilayers onto ibuprofen crystals was confirmed by optical microscopy. The drug release process, in a solution of pH 7.4, was monitored by optical microscopy and UV spectroscopy. The results revealed that the rate of release of ibuprofen from HSA/DMPA microcapsules decreased as the capsule wall thickness and drug crystal size increased, indicating that the permeability of the microcapsules can be controlled by simply varying the number of HSA/DMPA deposition cycles.