Long-Term Accumulation, Biological Effects and Toxicity of BSA-Coated Gold Nanoparticles in the Mouse Liver, Spleen, and Kidneys

Introduction

Gold nanoparticles are promising candidates as vehicles for drug delivery systems and could be developed into effective anticancer treatments. However, concerns about their safety need to be identified, addressed, and satisfactorily answered. Although gold nanoparticles are considered biocompatible and nontoxic, most of the toxicology evidence originates from in vitro studies, which may not reflect the responses in complex living organisms.

Methods

We used an animal model to study the long-term effects of 20 nm spherical AuNPs coated with bovine serum albumin. Mice received a 1 mg/kg single intravenous dose of nanoparticles, and the biodistribution and accumulation, as well as the organ changes caused by the nanoparticles, were characterized in the liver, spleen, and kidneys during 120 days.

Results

The amount of nanoparticles in the organs remained high at 120 days compared with day 1, showing a 39% reduction in the liver, a 53% increase in the spleen, and a 150% increase in the kidneys. The biological effects of chronic nanoparticle exposure were associated with early inflammatory and fibrotic responses in the organs and were more pronounced in the kidneys, despite a negligible amount of nanoparticles found in renal tissues.

Conclusion

Our data suggest, that although AuNPs belong to the safest nanomaterial platforms nowadays, due to their slow tissue elimination leading to long-term accumulation in the biological systems, they may induce toxic responses in the vital organs, and so understanding of their long-term biological impact is important to consider their potential therapeutic applications.

The Effect of Chemical Structure of OEG Ligand Shells with Quaternary Ammonium Moiety on the Colloidal Stabilization, Cellular Uptake and Photothermal Stability of Gold Nanorods

PURPOSE

Plasmonic photothermal cancer therapy by gold nanorods (GNRs) emerges as a promising tool for cancer treatment. The goal of this study was to design cationic oligoethylene glycol (OEG) compounds varying in hydrophobicity and molecular electrostatic potential as ligand shells of GNRs. Three series of ligands with different length of OEG chain (ethylene glycol units = 3, 4, 5) and variants of quaternary ammonium salts (QAS) as terminal functional group were synthesized and compared to a prototypical quaternary ammonium ligand with alkyl chain - (16-mercaptohexadecyl)trimethylammonium bromide (MTAB).

METHODS

Step-by-step research approach starting with the preparation of compounds characterized by NMR and HRMS spectra, GNRs ligand exchange evaluation through characterization of cytotoxicity and GNRs cellular uptake was used. A method quantifying the reshaping of GNRs was applied to determine the effect of ligand structure on the heat transport from GNRs under fs-laser irradiation.

RESULTS

Fourteen out of 18 synthesized OEG compounds successfully stabilized GNRs in the water. The colloidal stability of prepared GNRs in the cell culture medium decreased with the number of OEG units. In contrast, the cellular uptake of OEG+GNRs by HeLa cells increased with the length of OEG chain while the structure of the QAS group showed a minor role. Compared to MTAB, more hydrophilic OEG compounds exhibited nearly two order of magnitude lower cytotoxicity in free state and provided efficient cellular uptake of GNRs close to the level of MTAB. Regarding photothermal properties, OEG compounds evoked the photothermal reshaping of GNRs at lower peak fluence (14.8 mJ/cm2) of femtosecond laser irradiation than the alkanethiol MTAB.

CONCLUSION

OEG+GNRs appear to be optimal for clinical applications with systemic administration of NPs not-requiring irradiation at high laser intensity such as drug delivery and photothermal therapy inducing apoptosis.

Patent foramen ovale screening and prevention of decompression sickness in divers

Background/Introduction

Patent foramen ovale (PFO) is associated with increased risk of decompression sickness (DCS) due to paradoxical embolization of nitrogen bubbles that form during and after ascent. Screening for PFO using transcranial Doppler ultrasonography (TCD) is currently not recommended for all divers. If a diver is diagnosed with a high-grade PFO and wishes to continue diving there are currently two options to reduce the risk of DCS: catheter-based PFO closure or recommendation of conservative approach to diving. However, to date the evidence for the long-term effectiveness of these measures is limited.

Purpose

This study sought to compare the effectiveness of catheter-based PFO closure and conservative diving in the reduction of DCS incidence in divers with a high-grade PFO.

Methods

A total of 829 consecutive divers (35.4±10.0 yrs, 81.5% males) were screened for PFO between January 2006 and December 2018 by means of TCD. All patients were prospectively included in the study registry. Patients with a high-grade PFO were offered either catheter-based PFO closure (closure group) or advised to dive within the limits of recreational diving (conservative group). A trans-telephonic follow-up was performed at the end of the study. In this study we compared the incidence rate of DCS prior to enrollment and during the follow-up period in the closure and conservative group.

Results

Follow-up was available in 748 (90%) divers. Mean follow-up was 6.5±3.5 years. There were a total of 154 divers with a high-grade PFO that continued diving after the initial screening examination. Fifty-five (36%) of them underwent a catheter-based PFO closure (closure group), the remaining 98 divers were advised to dive within the limits of recreational diving (conservative group). The 55 divers in the closure group performed a total of 63,436 dives (30,684 prior to enrollment and 32,752 during the follow-up). Prior to enrollment there were 108 DCS episodes in 33 divers (incidence rate 3.3/1000 dives) and none during follow-up (p<0.001). The 98 divers in the conservative group performed a total of 48,069 dives (25,328 prior to enrollment and 22,741 during follow-up). There were 91 DCS episodes in 33 divers (incidence rate 3.6/1000 dives) prior to enrollment and 19 episodes in 11 divers (incidence rate 0.75/1000 dives) during follow-up (p<0.001). The incidence rate of DCS was similar for both groups prior to enrollment (p=0.196) but lower in the closure group during the post-interventional follow-up (p<0.001).

Conclusion(s)

In divers with a high-grade PFO both strategies decreased the incidence rate of DCS. Catheter-based PFO closure was more effective than conservative approach. The results also suggest that divers might benefit from screening for PFO.

Funding Acknowledgement

Type of funding source: None

Highly hydrophilic cationic gold nanorods stabilized by novel quaternary ammonium surfactant with negligible cytotoxicity

The photothermal cancer therapy using cationic gold nanorods (GNRs) stabilized by quaternary ammonium salts (QAS) have a great potential to enhance conventional cancer treatment as it promises the effective eradication of cancer cells including cells resistant to radio- and chemo-therapy and the stimulation of anti-tumor immune response. However, as the cytotoxicity of the conventional alkanethiol-QAS compounds limits their utility in medicine, here we developed GNRs modified by novel highly hydrophilic cationic surfactant composed of the quaternary ammonium group and ethylene glycol chain N,N,N-trimethyl-3,6,9,12,15-pentaoxaheptadecyl-17-sulfanyl-1-ammonium bromide (POSAB) showing insignificant cytotoxicity in the free state. Surface modification of GNRs by POSAB allowed to prepare nanoparticles with good stability in water, high cellular uptake and localization in lysosomes that are a promising alternative to alkanethiol-stabilized GNRs especially for biomedical applications.

Two-Step Mechanism of Cellular Uptake of Cationic Gold Nanoparticles Modified by (16-Mercaptohexadecyl)trimethylammonium Bromide

Cationic colloidal gold nanorods (GNRs) have a great potential as a theranostic tool for diverse medical applications. GNRs' properties such as cellular internalization and stability are determined by physicochemical characteristics of their surface coating. GNRs modified by (16-mercaptohexadecyl)trimethylammonium bromide (MTAB), ^MTABGNRs, show excellent cellular uptake. Despite their promise for biomedicine, however, relatively little is known about the cellular pathways that facilitate the uptake of GNRs, their subcellular fate and intracellular persistence. Here we studied the mechanism of cellular internalization and long-term fate of GNRs coated with MTAB, for which the synthesis was optimized to give higher yield, in various human cell types including normal diploid versus cancerous, and dividing versus nondividing (senescent) cells. The process of ^MTABGNRs internalization into their final destination in lysosomes proceeds in two steps: (1) fast passive adhesion to cell membrane mediated by sulfated proteoglycans occurring within minutes and (2) slower active transmembrane and intracellular transport of individual nanorods via clathrin-mediated endocytosis and of aggregated nanorods via macropinocytosis. The expression of sulfated proteoglycans was the major factor determining the extent of uptake by the respective cell types. Upon uptake into proliferating cells, ^MTABGNRs were diluted equally and relatively rapidly into daughter cells; however, in nondividing/senescent cells the loss of ^MTABGNRs was gradual and very modest, attributable mainly to exocytosis. Exocytosed ^MTABGNRs can again be internalized. These findings broaden our knowledge about cellular uptake of gold nanorods, a crucial prerequisite for future successful engineering of nanoparticles for biomedical applications such as photothermal cancer therapy or elimination of senescent cells as part of the emerging rejuvenation approach.

[Criteria for differential diagnosis in cardial symptoms; left- or right-sided chest pain?]

We studied the localization of pain in the acute phase of myocardial infarction in comparison with localization in non-cardiac chest pain. Myocardial infarction patients could not be differentiated from patients with non-cardiac chest pain in localization of pain on mid-chest, left side of the chest and left arm. However, myocardial infarction patients reported pain on the right side of the chest and in the right arm twice as often as non-cardiac chest pain patients. Results are similar when patients indicated the localization of the pain symptoms on attending the Emergency Coronary Care Unit, or when asked five days later. Pain symptoms on the right side of the chest and the right arm differentiate better between myocardial infarction and non-cardiac chest pain than the 'classical' symptom pattern.

High dietary fat intake and cigarette smoking as risk factors for ischaemic heart disease in Bangladeshi male immigrants in East London

A study was made of smoking and dietary habits in middle aged Bangladeshi men living in East London to investigate possible causes of the previously described high ischaemic heart disease risk in this group. The results showed that these individuals were 50% more likely to smoke than Caucasians living in the same area, after adjusting for age and social class. More striking, however, was the very high fat intake of over 200 g/day, which is twice the national average and accounted for nearly 60% of total energy intake. Interestingly, much of the dietary fat was from vegetable oil, and the ratio of polyunsaturated to saturated fatty acids exceeded the accepted recommended minimum.