Effect of Cyclodextrin Complexation on the Liposome Permeability of a Model Hydrophobic Weak Acid

Purpose  This study examines the effect of a chemically modified β-cyclodextrin on the liposome bilayer permeability of a liposomally entrapped model hydrophobic weak acid, DB-67 (7-t-butyldimethylsilyl-10-hydroxycamptothecin). Materials and Methods  Permeability studies were conducted in liposomes prepared by hydration–extrusion in the presence or absence of entrapped hydroxypropyl-β-cyclodextrin (HPβCD). A gradient HPLC method with evaporative light scattering detection was developed for analysis of HPβCD. DB-67 was analyzed by HPLC with fluorescence detection. Results  HPβCD entrapped in the aqueous compartment of liposomes was found to be membrane impermeable. Gel phase liposomes were stable in the presence of HPβCD. HPβCD complexation did not significantly alter the apparent permeability of DB67 lactone, due to its high membrane binding. However, lactone ring-opening and ionization significantly decreased the apparent permeability and improved the liposomal retention of DB-67, an effect that was amplified in the presence of 50 mM HPβCD. Conclusions  In liposomes, cyclodextrin complexation competes with liposomal membrane binding which may temper the potential benefit of complexation in prolonging hydrophobic drug retention. Cyclodextrin complexation combined with drug ionization may nevertheless significantly enhance the retention of ionizable hydrophobic drugs in liposomes as complexation may compete more favorably with membrane binding when the drug is ionized.     

Influence of agglomeration and specific lung lining lipid/protein interaction on short-term inhalation toxicity

Lung lining fluid is the first biological barrier nanoparticles (NPs) encounter during inhalation. As previous inhalation studies revealed considerable differences between surface functionalized NPs with respect to deposition and toxicity, our aim was to investigate the influence of lipid and/or protein binding on these processes. Thus, we analyzed a set of surface functionalized NPs including different SiO₂ and ZrO₂ in pure phospholipids, CuroSurf^TM and purified native porcine pulmonary surfactant (nS). Lipid binding was surprisingly low for pure phospholipids and only few NPs attracted a minimal lipid corona. Additional presence of hydrophobic surfactant protein (SP) B in CuroSurf^TM promoted lipid binding to NPs functionalized with Amino or PEG residues. The presence of the hydrophilic SP A in nS facilitated lipid binding to all NPs. In line with this the degree of lipid and protein affinities for different surface functionalized SiO₂ NPs in nS followed the same order (SiO₂ Phosphate?～?unmodified SiO₂?<?SiO₂ PEG?<?SiO₂ Amino NPs). Agglomeration and biomolecule interaction of NPs in nS was mainly influenced by surface charge and hydrophobicity. Toxicological differences as observed in short-term inhalation studies (STIS) were mainly influenced by the core composition and/or surface reactivity of NPs. However, agglomeration in lipid media and lipid/protein affinity appeared to play a modulatory role on short-term inhalation toxicity. For instance, lipophilic NPs like ZrO₂, which are interacting with nS to a higher extent, exhibited a far higher lung burden than their hydrophilic counterparts, which deserves further attention to predict or model effects of respirable NPs.     

Non-covalent ligand conjugation to biotinylated DNA nanoparticles using TAT peptide genetically fused to monovalent streptavidin

DNA nanoparticles (DNA NPs), which self-assemble from DNA plasmids and poly-L-lysine (pLL)-polyethylene glycol (PEG) block copolymers, transfect several cell types in vitro and in vivo with minimal toxicity and immune response. To further enhance the gene transfer efficiency of DNA NP and control its tropism, we established a strategy to efficiently attach peptide ligands to DNA NPs. The non-covalent biotin–streptavidin (SA) interaction was used for ligand conjugation to overcome problems associated with covalent conjugation methods. A fusion protein of SA with the HIV-1 TAT peptide was cloned, expressed, purified and attached to biotinylated DNA NPs. A modified SA system with tetrameric structure but monovalent biotin binding capacity was adopted and shown to reduce the aggregation of biotinylated DNA NPs compared to neutravidin. Compared to unmodified DNA NPs, TAT modified DNA NPs significantly enhanced in vitro gene transfer, particularly at low DNA concentrations. Studies of cellular uptake and cellular distribution of the DNA NPs indicated that attaching TAT enhanced binding of DNA NPs to cell surface but not internalization at high DNA concentrations. In vivo studies showed that TAT modified DNA NPs mediated equal level of gene transfer to the mouse airways via the luminal route compared to unmodified DNA NPs.     

Spermiotoxicity of nickel nanoparticles in the marine invertebrate Ciona intestinalis (ascidians)

Nickel nanoparticles (Ni NPs) are increasingly used in modern industries as catalysts, sensors, and in electronic applications. Due to this large use, their inputs into marine environment have significantly increased; however, the potential ecotoxicological effects in marine environment have so far received little attention. In particular, little is known on the impact of NPs on gamete quality of marine organisms and on the consequences on fertility potential. The present study examines, for the first time, the impact of Ni NPs exposure on sperm quality of the marine invertebrate Ciona intestinalis (ascidian). Several parameters related with sperm status such as plasma membrane lipid peroxidation, mitochondrial membrane potential (MMP), intracellular pH, DNA integrity, and fertilizing ability were assessed as toxicity end points after exposure to different Ni NPs concentrations. Ni NPs generate oxidative stress that in turn induces lipid peroxidation and DNA fragmentation, and alters MMP and sperm morphology. Furthermore, sperm exposure to Ni NPs affects their fertilizing ability and causes developmental anomalies in the offspring. All together, these results reveal a spermiotoxicity of Ni NPs in ascidians suggesting that the application of these NPs should be carefully assessed as to their potential toxic effects on the health of marine organisms that, in turn, may influence the ecological system. This study shows that ascidian sperm represent a suitable and sensitive tool for the investigation of the toxicity of NPs entered into marine environment, for defining the mechanisms of toxic action and for the environmental monitoring purpose.     

Toxic response of nickel nanoparticles in human lung epithelial A549 cells

Nickel nanoparticle (Ni NP) is increasingly used in modern industries such as catalysts, sensors and electronic applications. Due to wide-spread industrial applications the inhalation is the primary source of exposure to Ni NPs. However, data demonstrating the effect of Ni NPs on the pulmonary system remain scarce. The present study was designed to examine the toxic effect of human lung epithelial A549 cells treated with well characterized Ni NPs at the concentrations of 0, 1, 2, 5, 10 and 25 μg/ml for 24 and 48 h. Mitochondrial function (MTT assay), membrane leakage of lactate dehydrogenase (LDH assay), reduced glutathione (GSH), reactive oxygen species (ROS), membrane lipid peroxidation (LPO) and caspase-3 activity were assessed as toxicity end points. Results showed that Ni NPs reduced mitochondrial function and induced the leakage of LDH in dose and time-dependent manner. Ni NPs were also found to induce oxidative stress in dose and time-dependent manner indicated by depletion of GSH and induction of ROS and LPO. Further, activity of caspase-3 enzyme, marker of apoptosis was significantly higher in treated cells with time and Ni NPs dosage. The results exhibited significant toxicity of Ni NPs in human lung epithelial A549 cells which is likely to be mediated through oxidative stress. This study warrants more careful assessment of Ni NPs before their industrial applications.     

Interaction of Native Bile Acids with Human Apical Sodium-Dependent Bile Acid Transporter (hASBT): Influence of Steroidal Hydroxylation Pattern and C-24 Conjugation

Purpose The human apical sodium-dependent bile acid transporter (hASBT) is a potential target for drug delivery, but an understanding of hASBT substrate requirements is lacking. The objective of this study was to characterize hASBT interaction with its native substrates, bile acids, and to evaluate C-24 conjugation and steroidal hydroxylation on transport affinity and inhibition potency. Methods Transport and inhibition kinetics of 15 bile acids were evaluated (cholate, chenodeoxycholate, deoxycholate, ursodeoxycholate, and lithocholate, including their glycine and taurine conjugates) with an hASBT–Madin-Darby canine kidney (MDCK) monolayer assay. Samples were analyzed via liquid chromatography–mass spectrometry (LC-MS) or chromatography–mass spectrometry–mass spectrometry (LC-MS-MS). Results C-24 conjugation improved the inhibitory potency of all native bile acids. There was an inverse association between number of steroidal hydroxyl groups and inhibitory potency. Glycolithocholate and taurolithocholate were the most potent inhibitors. Results from transport studies followed trends from inhibition studies. Conjugated dihydroxy and monohydroxy bile acids exhibited the highest hASBT-mediated transport (i.e., lower K_t and higher J_max). Across the 15 bile acids, K_t generally followed K_i. Additionally, J_max correlated with K_i, where greater inhibition potency was associated with higher transport capacity. Conclusion C-24 conjugation and steroidal hydroxylation pattern modulated native bile acid interaction with hASBT, with C-24 effect dominating steroidal hydroxylation effect. Results indicate that bile acid binding to hASBT may be the rate-limiting step in the apical transport of bile acids.     

Long Circulating Poly(Ethylene Glycol)-Decorated Lipid Nanocapsules Deliver Docetaxel to Solid Tumors

Purpose The purpose of this study was to evaluate the ability of poly(ethylene glycol)-coated lipid nanocapsules (LN) to deliver the highly potent hydrophobic anticancer drug docetaxel to solid tumors. Methods Docetaxel-loaded nanocapsules (80–120 nm) were produced by a solvent-free phase inversion process and were coated with polyethylene glycol distearoylphosphatidylethanolamine conjugate by a postinsertion step. In vivo studies were conducted in mice bearing subcutaneously implanted C26 colon adenocarcinoma to assess the pharmacokinetics and biodistribution of both the drug and LN. Results Incorporation of docetaxel into the LN dramatically increased the drug's biological half-life while providing substantial accumulation at the tumoral site. The pharmacokinetics and biodistribution pattern were found to depend on the specific surface area and shell composition of the nanocapsules. Conclusion This study demonstrates that docetaxel physically entrapped into a lipid colloidal drug carrier can be efficiently targeted to neoplastic tissues.     

The interaction of nanoparticles with plasma proteins and the consequent influence on nanoparticles behavior

Introduction: Plasma protein binding with nanoparticles (NPs) occurs immediately upon their introduction into a physiological environment and is affected by the characteristics of NPs, including their composition, size, shape and surface properties. According to their specific functions, adsorbed proteins can be divided into opsonins and dysopsonins. Opsonins often induce the rapid blood clearance of NPs, while dysopsonins benefit prolonged blood circulation.

Areas covered: This review discusses the influential factors that are involved in the interaction between NPs and plasma proteins. The influence of this interaction on distribution of NPs was reviewed followed by the function and influence of ligand modification.

Expert opinion: Protein adsorption is a key element that influences biological responses, such as endocytosis and biodistribution, and also contributes to the characteristics of NPs and the physiological environment. By contrast, the surface modification of ligands is a common and useful method to functionalize NPs to provide an engineered targeting effect. The protein adsorption of ligand-modified NPs is even more important and requires in-depth discussion. Differences between modified and unmodified NPs lead to varying degrees of opsonization, which greatly affects targeting and may result in opposing effects. Understanding these influences is necessary to improve targeting effects and reduce defects in protein adsorption, which are crucial for drug delivery.     

A New Polymer–Lipid Hybrid Nanoparticle System Increases Cytotoxicity of Doxorubicin Against Multidrug-Resistant Human Breast Cancer Cells

Purpose This work is intended to develop and evaluate a new polymer–lipid hybrid nanoparticle system that can efficiently load and release water-soluble anticancer drug doxorubicin hydrochloride (Dox) and enhance Dox toxicity against multidrug-resistant (MDR) cancer cells. Methods Cationic Dox was complexed with a new soybean-oil-based anionic polymer and dispersed together with a lipid in water to form Dox-loaded solid lipid nanoparticles (Dox–SLNs). Drug loading and release properties were measured spectrophotometrically. The in vitro cytotoxicity of Dox–SLN and the excipients in an MDR human breast cancer cell line (MDA435/LCC6/MDR1) and its wild-type line were evaluated by trypan blue exclusion and clonogenic assays. Cellular uptake and retention of Dox were determined with a microplate fluorometer. Results Dox–SLNs were prepared with a drug encapsulation efficiency of 60–80% and a particle size range of 80–350 nm. About 50% of the loaded drug was released in the first few hours and an additional 10–20% in 2 weeks. Treatment of the MDR cells with Dox–SLN resulted in over 8-fold increase in cell kill when compared to Dox solution treatment at equivalent doses. The blank SLN and the excipients exhibited little cytotoxicity. The biological activity of the released Dox remained unchanged from fresh, free Dox. Cellular Dox uptake and retention by the MDR cells were both significantly enhanced (p < 0.05) when Dox was delivered in Dox–SLN form. Conclusions The new polymer–lipid hybrid nanoparticle system is effective for delivery of Dox and enhances its efficacy against MDR breast cancer cells.     

Correlation of acetylator phenotype with peripheral, autonomic and central neuropathy in Northern Indian non-insulin-dependent diabetes mellitus patients

Objectives: Genetic susceptibility to diabetic neuropathy has been suspected and tentatively explored; however, diabetic autonomic and central neuropathies are poorly investigated areas. Previous trials correlating types of diabetes and diabetic neuropathy with acetylator dimorphisms have not been conclusive. The present study was designed to test peripheral neuropathy, autonomic neuropathy and integrity of central conduction pathways in patients of non-insulin-dependent diabetes mellitus (NIDDM), and to correlate the findings with the acetylator phenotype. Methods: Twenty-six patients of NIDDM with stable glycaemic control and 11 age- and sex-matched control subjects were recruited, clinically examined and investigated with glycaemic and lipid profile, renal function tests, nerve conduction studies (sensory and motor), auditory brain stem evoked responses (ABERs) and somatosensory evoked potentials (SEPs). Acetylator status of the subjects was determined by sulphadimidine test. Results: Out of 26 NIDDM patients, eight (30.7%; group 1A) were slow acetylators and 18 (69.3%; group 1B) were fast acetylators. The distribution of slow and rapid acetylators in both the groups was similar. Glycaemic and lipid profiles and 24-h urinary albumin excretion in groups 1A and 1B were also similar. Motor nerve conduction velocity, latency of F wave, sensory nerve conduction and amplitudes of sensory nerve action potentials were not different between fast and slow acetylator NIDDM patients. On testing for ABERs, there were no statistically significant differences in peak latencies of waves I, III and V; interpeak latencies (IPLs) I–III, III–V and I–V; amplitude of waves I, III and V on both sides between NIDDM patients and controls. However, peak latencies of wave III (P < 0.01), wave V (P < 0.005), IPLs I–III and I–V (P < 0.005), IPLs III–V (P < 0.05), and amplitudes of wave I (P < 0.05) and wave V (P < 0.05) on the left side were significantly different in slow acetylator NIDDM patients. Increase on the right side for the same group was statistically significant for IPLs I–III and I–V (P < 0.05). SEPs showed no statistically significant difference between NIDDM patients and controls, and slow and fast acetylator NIDDM patients. Conclusions: No significant association of acetylator status with peripheral neuropathy in NIDDM subjects was observed in the present study. However, central neural conduction, primarily tested by ABERs, was significantly delayed in slow acetylators compared with fast acetylator NIDDM patients. Hence, there may be a predisposition to neuropathy in this group of patients, and such a predisposition may be better detected by studying central rather than peripheral nervous conduction pathways in NIDDM patients. Received: 29 September 1998 / Accepted in revised form: 9 February 1999     

Augmented responses to morphine and cocaine in mice with a 12-lipoxygenase gene disruption

Rationale Recent studies have shown that pharmacological inhibition of the 12-lipoxygenase pathway selectively blocks opioid inhibition of GABAergic synaptic currents. A similar mechanism has been shown for the regulation of glutamate release in the ventral tegmental area (VTA) during acute withdrawal from morphine, although the functional significance of these effects in vivo are not known.Objectives We have utilized mice with a disruption of the "leukocyte-type" 12-lipoxygenase gene (12-LO^–/– mice) to examine a variety of general behavioral responses as well as several specific responses to morphine and cocaine.Methods Behavioral responses to morphine include sensitivity to thermal stimuli and withdrawal from chronic morphine treatment. Responses to cocaine were measured through locomotor activity.Results General behavioral responses in 12-LO^–/– mice are not different from their wild-type controls. However, these mutant mice showed enhanced morphine-induced analgesia. However, this effect is eliminated following chronic morphine treatment. In addition, 12-LO^–/– mice demonstrated enhanced somatic signs of opiate withdrawal relative to littermate controls. Lastly, cocaine-mediated increases in locomotor activity was augmented acutely but not chronically in 12-LO^–/– mice.Conclusions Together, these results suggest a role for metabolites of arachidonic acid metabolism in morphine- and cocaine-induced behavioral responses and may reflect a utilization of this pathway following acute but not chronic drug administration.     

Comparative cytotoxicity of dolomite nanoparticles in human larynx HEp2 and liver HepG2 cells

Dolomite is a natural mineral of great industrial and commercial importance. With the advent of nanotechnology, natural minerals including dolomite in the form of nanoparticles (NPs) are being utilized in various applications to improve the quality of products. However, safety or toxicity information of dolomite NPs is largely lacking. This study evaluated the cytotoxicity of dolomite NPs in two widely used in vitro cell culture models: human airway epithelial (HEp2) and human liver (HepG2) cells. Concentration‐dependent decreased cell viability and damaged cell membrane integrity revealed the cytotoxicity of dolomite NPs. We further observed that dolomite NPs induce oxidative stress in a concentration‐dependent manner, as indicated by depletion of glutathione and induction of reactive oxygen species (ROS) and lipid peroxidation. Quantitative real‐time PCR data demonstrated that the mRNA level of tumor suppressor gene p53 and apoptotic genes (bax, CASP3 and CASP9) were up‐regulated whereas the anti‐apoptotic gene bcl‐2 was down‐regulated in HEp2 and HepG2 cells exposed to dolomite NPs. Moreover, the activity of apoptotic enzymes (caspase‐3 and caspase‐9) was also higher in both kinds of cells treated with dolomite NPs. It is also worth mentioning that HEp2 cells seem to be marginally more susceptible to dolomite NPs exposure than HepG2 cells. Cytotoxicity induced by dolomite NPs was efficiently prevented by N‐acetyl cysteine treatment, which suggests that oxidative stress is primarily responsible for the cytotoxicity of dolomite NPs in both HEp2 and HepG2 cells. Toxicity mechanisms of dolomite NPs warrant further investigations at the in vivo level. Copyright © 2015 John Wiley & Sons, Ltd.     

Comparative CYP-dependent binding of the adrenocortical toxicants 3-methylsulfonyl–DDE and <Emphasis Type="Italic">o</Emphasis>,<Emphasis Type="Italic">p</Emphasis>′-DDD in Y-1 adrenal cells

The environmental pollutant 3-MeSO₂–DDE [2-(3-methylsulfonyl-4-chlorophenyl)-2-(4-chlorophenyl)-1,1-dichloroethene] is an adrenocortical toxicant in mice, specifically in the glucocorticoid-producing zona fasciculata, due to a cytochrome P450 11B1 (CYP11B1)-catalysed bioactivation and formation of covalently bound protein adducts. o,p′-DDD [2-(2-chlorophenyl)-2-(4-chlorophenyl)-1,1-dichloroethane] is toxic and inhibits steroidogenesis in the human adrenal cortex after bioactivation by unidentified CYPs, but does not exert any toxic effects on the mouse adrenal. As a step towards determining in vitro/in vivo relationships for the CYP-catalysed binding and toxicity of 3-MeSO₂–DDE and o,p′-DDD, we have investigated the irreversible protein binding of these two toxicants in the murine adrenocortical cell line Y-1. The irreversible binding of 3-MeSO₂–DDE previously demonstrated in vivo was successfully reproduced and could be inhibited by the CYP-inhibitors etomidate, ketoconazole and metyrapone. Surprisingly, o,p′-DDD reached similar levels of binding as 3-MeSO₂–DDE. The binding of o,p′-DDD was sensitive to etomidate and ketoconazole, but not to metyrapone. Moreover, GSH depletion increased the binding of 3-MeSO₂–DDE, but not of o,p′-DDD, indicating an important role of GSH conjugation in the detoxification of the 3-MeSO₂–DDE-derived reactive metabolite. In addition, the specificity of CYP11B1 in activating 3-MeSO₂–DDE was investigated using structurally analogous compounds. None of the analogues produced histopathological lesions in the mouse adrenal in vivo following a single i.p. injection of 100 mg/kg body weight, but two of the compounds were able to decrease the irreversible binding of 3-MeSO₂–DDE to Y-1 cells. These results indicate that the bioactivation of 3-MeSO₂–DDE by CYP11B1 is highly structure-dependent. In conclusion, both 3-MeSO₂–DDE and o,p′-DDD bind irreversibly to Y-1 cells despite differences in binding and adrenotoxicity in mice in vivo. This reveals a notable in vitro/in vivo discrepancy, the contributing factors of which remain unexplained. We consider the Y-1 cell line as appropriate for studies of the cellular mechanisms behind the adrenocortical toxicity of these substances.     

iRGD-mediated core-shell nanoparticles loading carmustine and O6-benzylguanine for glioma therapy

iRGD (internalizing RGD) with high affinity to αν integrins was reported to enhance tumor penetrability by binding to neuropilin-1 (NRP-1). Based on our previous study, chitosan surface-modified poly (lactide-co-glycolides) nanoparticles (PLGA/CS NPs), loaded with carmustine (BCNU) and its sensitizer (O⁶-benzylguanine, BG) showed stronger anti-tumor effect than free drugs. In present study, PLGA/CS NPs (NPs) with core-shell structure were prepared and modified with iRGD or mPEG. F98, C6 or U87 cell lines with different receptors levels were selected for in vitro and in vivo studies. After administration of iRGD-mediated NPs, including iRGD-modified NPs (iRGD-NPs) and co-administration of iRGD and NPs (iRGD?+?NPs), their effects on glioma were compared with NPs. iRGD-NPs showed stronger cytotoxicity and cellular uptake than other groups. iRGD-NPs and iRGD?+?NPs displayed deeper tumor penetration and stronger anti-invasion effect on three dimensional (3D) glioma spheroids than NPs. On F98 glioma-bearing mice model, iRGD-mediated NPs showed enhanced crossing BBB ability and brain tumor accumulation levels. Correspondingly, the median survival time of iRGD?+?NPs, iRGD-NPs and NPs groups were 58, 49 and 34.5 days, respectively. Present studies supported the iRGD-mediated strategy to improve the efficacy of antitumor drug delivery system. Importantly, co-administration of iRGD may be a greater way over the conjugation of iRGD.     

Identification of serum proteins bound to industrial nanomaterials

Nanoparticles (NPs) are decorated with proteins and other biomolecules when they get into contact with biological systems. The presence of proteins in cell culture medium can therefore have effects on the biological outcome in cell-based tests. In this study, the manufactured nanomaterials silicon dioxide (SiO₂), titanium dioxide (TiO₂), iron-III-oxide (Fe₂O₃), and carbon black (CB) were used to study their interaction with single proteins from bovine and human plasma (albumin, fibrinogen and IgG) as well as with complete human serum. The protein binding capacity of the material was investigated and 1D gel electrophoresis was used to separate the bound proteins and to identify the bands by matrix-assisted laser desorption/ionisation-time-of-flight (MALDI-TOF) mass spectrometry.We found that the NP surface chemistry had a great impact on the amount of bound protein with distinct ligands for each of the tested particles. The hydrophobic CB NPs bound much more protein than the hydrophilic metal oxide NPs. Among the single proteins investigated, fibrinogen showed the strongest affinity for SiO₂, TiO₂ and CB NPs. The identified proteins from human serum adsorbed to these NPs were very different. Only apolipoprotein A1 was found to be adsorbed to all NPs.These studies will help to explain the different degree of biological responses observed after in vitro exposure of cells in the absence or presence of serum and might also support the interpretation of in vivo experiments were NPs come directly into contact with blood plasma.     

Lipid nanocapsule as vaccine carriers for his-tagged proteins: Evaluation of antigen-specific immune responses to HIV I His-Gag p41 and systemic inflammatory responses

The purpose of this study was to design novel nanocapsules (NCs) with surface-chelated nickel (Ni-NCs) as a vaccine delivery system for histidine (His)-tagged protein antigens. Ni-NCs were characterized for binding His-tagged model proteins through high-affinity non-covalent interactions. The mean diameter and zeta potential of the optimized Ni-NCs were 214.9 nm and −14.8 mV, respectively. The optimal binding ratio of His-tagged Green Fluorescent Protein (His-GFP) and His-tagged HIV-1 Gag p41 (His-Gag p41) to the Ni-NCs was 1:221 and 1:480 w/w, respectively. Treatment of DC2.4 cells with Ni-NCs did not result in significant loss in the cell viability up to 24 h (<5%). We further evaluated the antibody response of the Ni-NCs using His-Gag p41 as a model antigen. Formulations were administered subcutaneously to BALB/c mice at day 0 (prime) and 14 (boost) followed by serum collection on day 28. Serum His-Gag p41-specific antibody levels were found to be significantly higher at 1 and 0.5 μg doses of Gag p41-His-Ni-NCs (His-Gag p41 equivalent) compared with His-Gag p41 (1 μg) adjuvanted with aluminum hydroxide (AH). The serum IgG2a levels induced by Gag p41-His-Ni-NCs (1 μg) were significantly higher than AH adjuvanted His-Gag p41. The Ni-NCs alone did not result in the elevation of systemic IL-12/p40 and CCL5/RANTES inflammatory cytokine levels upon subcutaneous administration in BALB/c mice. In conclusion, the proposed Ni-NCs can bind His-tagged proteins and have the potential to be used as antigen delivery system capable of generating strong antigen-specific antibodies at doses much lower than with aluminum-based adjuvant and causing no significant elevation of systemic pro-inflammatory IL-12/p40 and CCL5/RANTES cytokines.     

Pulmonary clearance and inflammatory potency of intratracheally instilled or acutely inhaled nickel sulfate in rats

Rats were exposed to nickel sulfate (NiSO₄) either by intratracheal (IT) instillation or by acute aerosol inhalation, and pulmonary clearance of Ni and pulmonary inflammatory responses were studied. The half-time of Ni in the lung (initial lung burden = 50 μg Ni/rat) was about 32 h in both the IT instillation and inhalation groups. Ni retention in the lung tissue following IT instillation of NiSO₄ was saturable with reference to dose, suggesting that clearance rate of Ni from the rat lung depends on lung burden of Ni. Lung inflammatory responses were evaluated by biochemical, elemental and cytological indicators in bronchoalveolar lavage fluid (BALF) following IT instillation of NiSO₄. Activities of lactate dehydrogenase and β-glucuronidase, contents of lysozyme, protein, sulfur and calcium, and the number of polymorphonuclear leukocytes were increased with a peak at 2 – 3 days post-instillation, while BALF alkaline phosphatase (ALP) activity was significantly decreased after IT instillation of NiSO₄. Lung tissue ALP activity was also decreased by NiSO₄. Because Ni does not inhibit ALP directly, the decrease in ALP activity is probably due to functional changes of type II cells (a major source of BALF ALP). Thiobarbituric acid reacting substances in the lung tissue were not changed by NiSO₄, suggesting that lipid peroxidation plays a minimal, if any role, in the Ni-induced inflammation in the rat lung. Received: 1 December 1993/Accepted: 16 March 1994     

Reproductive toxicity induced by nickel nanoparticles in Caenorhabditis elegans

To investigate the reproductive toxicity and underlying mechanism of nickel nanoparticles (Ni NPs), Caenorhabditis elegans (C. elegans ) were treated with/without 1.0, 2.5, and 5.0 μg cm^?2 of Ni NPs or nickel microparticles (Ni MPs). Generation time, fertilized egg numbers, spermatide activation and motility were detected. Results indicated, under the same treatment doses, that Ni NPs induced higher reproductive toxicity to C. elegans than Ni MPs. Reproductive toxicities observed in C. elegans included a decrease in brood size, fertilized egg and spermatide activation, but an increase in generation time and out‐of‐round spermatids. The reproductive toxicity of Ni NPs on C. elegans may be induced by oxidative stress. The reproductive toxicity in C. elegans induced by Ni NPs is consistent with our previous results in the rats. Therefore, C. elegans can be used as an alternative model to detect the early reproductive toxicity of Ni NPs exposure. © 2016 Wiley Periodicals, Inc. Environ Toxicol 32: 1530–1538, 2017.     

Study of the interaction between nucleic acids and the daunoblastina aluminum (III) complex

In this study, the interactions between aluminum (III)–daunoblastina (DBS) complex and nucleic acids (DNA), and the combination of DBS and Al (III) were studied using ultraviolet (UV)–visible absorption and fluorescence spectra. The experiment results showed that DBS could bind to Al³⁺ and that a binary complex DBS–Al³⁺ could be formed. The Al³⁺–DBS binary complex could also combine with DNA and a ternary complex Al³⁺–DBS–DNA can be formed. The interaction mode between Al³⁺–DBS complex and DNA is intercalation binding. The binding constant K was 5.8 × 10³ L/mol and the binding number was 4. Both the melting curve and fluorescence polarization agreed with the above conclusions of the interaction mechanism. This study has significant value for studies of the reduction of DBS’s cardiotoxicity and pharmacological studies of cancer treatments using Al³⁺–DBS as a drug.