Effect of concentration of PEG coated gold nanoparticle on lung surfactant studied with coarse-grained molecular dynamics simulations

Aggravated visual toxicity in zebrafish larvae upon co-exposure to titanium dioxide nanoparticles and bis(2-ethylhexyl)-2,3,4,5-tetrabromophthalate

The bioavailability and toxicity of organic pollutants in aquatic organisms can be largely affected by the co-existed nanoparticles. However, the impacts of such combined exposure on the visual system remain largely unknown. Here, we systematically investigated the visual toxicity in zebrafish larvae after single or joint exposure to titanium dioxide nanoparticles (n-TiO2) and bis(2-ethylhexyl)-2,3,4,5-tetrabromophthalate (TBPH) at environmentally relevant levels. Molecular dynamics simulations revealed the enhanced transmembrane capability of the complex than the individual, which accounted for the increased bioavailability of both TBPH and n-TiO2 when combined exposure to zebrafish. Transcriptome analysis showed that co-exposure to n-TiO2 and TBPH interfered with molecular pathways related to eye lens structure and sensory perception of zebrafish. Particularly, n-TiO2 or TBPH significantly suppressed the expression of βB1-crystallin and rhodopsin in zebrafish retina and lens, which was further enhanced after co-exposure. Moreover, we detected disorganized retinal histology, stunted lens development and significant visual behavioral changes of zebrafish under co-exposure condition. The overall results suggest that combined exposure to water borne n-TiO2 and TBPH increased their bioavailability, resulted in severer damage to optic nerve development and ultimately abnormal visual behavior patterns, highlighting the higher potential health risks of co-exposure to aquatic vertebrates.

Monitoring the Interaction Between Solid Lipid Nanoparticles and Alveolar Macrophages Via the Label-Free Technique

Macrophages are employed as targets for delivering genes, drugs, or lipid nanoparticles into tumors or other specific sites. Studying the interaction between solid lipid nanoparticles (SLNs) and macrophages is essential for assessing nanotoxicity and advancing the development of nanomedicines. However, limited data are currently available on the membrane microstructure and biochemical changes that occur when macrophages interact with SLNs. We conducted a label-free morphological and biochemical investigation of NR8383 macrophages using optical diffraction tomography (ODT), which validated the efficiency of the SLNs as a drug delivery system. ODT provided intracellular holotomography to characterize the macrophages and fluorescence imaging to analyze delivery efficiency. ODT analysis revealed the responses of phagocytic macrophages. Additionally, a quantitative analysis of lipid droplets using refractive indices revealed that, compared with incubation with normal cells, incubation with SLNs significantly increased the lipid droplet volume and surface area. The uptake of SLNs into macrophages resulted in increased cell volume, surface area, and concentration, which indicated greater morphological and biochemical variability in the treated cells than in the control cells. The results suggest that ODT imaging is promising for understanding the intracellular distribution of SLNs and useful for validating the efficacy of delivery of SLNs to macrophages.

Therapeutic Peptides Are Preferentially Solubilized in Specific Microenvironments within PEG-PLGA Polymer Nanoparticles

Polymeric nanoparticles are a highly promising drug delivery formulation. However, a lack of understanding of the molecular mechanisms that underlie their drug solubilization and controlled release capabilities has hindered the efficient clinical translation of such technologies. Polyethylene glycol-poly(lactic-co-glycolic) acid (PEG-PLGA) nanoparticles have been widely studied as cancer drug delivery vehicles. In this letter, we use unbiased coarse-grained molecular dynamics simulations to model the self-assembly of a PEG-PLGA nanoparticle and its solubulization of the anticancer peptide, EEK, with good agreement with previously reported experimental structural data. We applied unsupervised machine learning techniques to quantify the conformations that polymers adopt at various locations within the nanoparticle. We find that the local microenvironments formed by the various polymer conformations promote preferential EEK solubilization within specific regions of the NP. This demonstrates that these microenvironments are key in controlling drug storage locations within nanoparticles, supporting the rational design of nanoparticles for therapeutic applications.

Toxicity of metal-based nanoparticles: Challenges in the nano era

With the rapid progress of nanotechnology, various nanoparticles (NPs) have been applicated in our daily life. In the field of nanotechnology, metal-based NPs are an important component of engineered NPs, including metal and metal oxide NPs, with a variety of biomedical applications. However, the unique physicochemical properties of metal-based NPs confer not only promising biological effects but also pose unexpected toxic threats to human body at the same time. For safer application of metal-based NPs in humans, we should have a comprehensive understanding of NP toxicity. In this review, we summarize our current knowledge about metal-based NPs, including the physicochemical properties affecting their toxicity, mechanisms of their toxicity, their toxicological assessment, the potential strategies to mitigate their toxicity and current status of regulatory movement on their toxicity. Hopefully, in the near future, through the convergence of related disciplines, the development of nanotoxicity research will be significantly promoted, thereby making the application of metal-based NPs in humans much safer.

Polyethylene glycol capped gold nanoparticles ameliorate renal ischemia-reperfusion injury in diabetic mice through AMPK-Nrf2 signaling pathway

The aim of this study is to investigate the protective effect of polyethylene glycol capped gold nanoparticles (PEG-AuNPs) on renal ischemia-reperfusion injury (I/R)-induced acute kidney injury (AKI) in diabetic mice via the activation of adenosine 5' monophosphate-activated protein kinase-nuclear factor erythroid-2-related factor-2 (AMPK-Nrf2) pathway. Diabetes was induced in male mice (12/group) by streptozotocin (50 mg/kg) for 5 consecutive days. After 4 weeks, the mice have intravenously received doses of PEG-AuNPs (40, 150, and 400 µg/kg body weight) for 3 consecutive days, and then animals were subjected to 30 min ischemia and 48 h reperfusion. Following the treatment with three different doses of PEG-AuNPs, the levels of blood urea nitrogen (BUN) and creatinine were reduced. Obvious reduction in renal tubular atrophy, glomerular damage, mitochondrial damage, and necrotic area were ultra-structurally detected, and renal interstitial inflammation and apoptosis were diminished. Moreover, PEG-AuNPs increased the recovering of damaged renal cells, suppressed significantly levels of malondialdehyde (MDA), downregulated significantly the level of inflammatory cytokines (TNF-α and IL-1β), and upregulated the AMPK-Nrf2 pathway. PEG-AuNPs exhibited a promising alternative therapeutic target for diabetic renal I/R-induced AKI through upregulation of AMPK/PI3K/AKT path which additionally stimulated Nrf2-regulated antioxidant enzymes in a dose-dependent manner.

Permeation of Nanoparticles into Pulmonary Surfactant Monolayer: In Situ X-ray Standing Wave Studies

High-resolution X-ray techniques were applied to examine the effects of gold nanoparticles (size <5 nm) on natural pulmonary surfactant and pure DPPC monolayers preliminarily formed on water subphase in a Langmuir trough. Hydrophobic and hydrophilic nanoparticles were delivered from nanoaerosol using electrodeposition method. Grazing incidence diffraction, X-ray reflectivity, and X-ray standing wave measurements allow to monitor the changes in molecular organization of lipid monolayer and to locate the position of gold nanoparticles. X-ray experiments were performed over a period of 9-14 h. The obtained results evidenced that, on a long time scale, the deposition of nanoparticles, even at low doses, can induce pronounced alterations in lipid monolayer. The presented data can help to elucidate the mechanism of pulmonary translocation of inhaled nanoparticles that is of special interest for biomedical investigations of potential risk of nanoaerosols for human health.

Molecular dynamics simulation insights into the cellular uptake of elastic nanoparticles through human pulmonary surfactant

The interaction between inhaled nanoparticles (NPs) and the pulmonary surfactant (PS) monolayer has drawn significant attention due to its potential in drug delivery design and application for respiratory therapeutics in active and passive cellular uptake pathways. Even though much attention has been given to explore the interaction between NPs and the PS monolayer, the effects of the NP elasticity on the translocation across the PS monolayer have not been thoroughly studied. Here, we performed a series of coarse-grained (CG) molecular dynamics simulations to study active or passive cellular uptake pathways of three NPs with different elasticities through a PS monolayer. The differences between active and passive pathways underly the enhanced targeting ability by ligand–receptor interaction (L–R interaction). In the active or passive cellular uptake pathways, it is found that the increase in stiffness level leads to a higher penetrability of NPs at the same time range. The soft NP has always been withheld inside the PS monolayer due to the lowest level of elasticity, while the other two types of NPs penetrate through the PS monolayer as the simulation progresses toward the end. The NPs in the active cellular uptake pathways take a longer time to penetrate the PS monolayer, resulting in a longer average penetration distance of approximately 40.55% and a higher average number of contacts, approximately 36.11%, than passive cellular uptake pathways, due to the L–R interaction. Moreover, it demonstrates that NPs in active cellular uptake pathways have a significantly higher targeting ability with the PS monolayer. We conclude that the level of NP elasticities has a substantial link to the penetrability in active or passive cellular uptake pathways. These results provide valuable insights into drug delivery and nanoprobe design for inhaled NPs within the lungs.

Adjusting inhaled NP elasticity affects their permeability across the human pulmonary surfactant monolayer.

Molecular Structure Effect of a Self-Assembled Monolayer on Thermal Resistance across an Interface

Understanding heat transfer across an interface is essential to a variety of applications, including thermal energy storage systems. Recent studies have shown that introducing a self-assembled monolayer (SAM) can decrease thermal resistance between solid and fluid. However, the effects of the molecular structure of SAM on interfacial thermal resistance (ITR) are still unclear. Using the gold–SAM/PEG system as a model, we performed nonequilibrium molecular dynamics simulations to calculate the ITR between the PEG and gold. We found that increasing the SAM angle value from 100° to 150° could decrease ITR from 140.85 × 10⁻⁹ to 113.79 × 10⁻⁹ m² K/W owing to penetration of PEG into SAM chains, which promoted thermal transport across the interface. Moreover, a strong dependence of ITR on bond strength was also observed. When the SAM bond strength increased from 2 to 640 kcal⋅mol−1Å−2, ITR first decreased from 106.88 × 10⁻⁹ to 102.69 × 10⁻⁹ m² K/W and then increased to 123.02 × 10⁻⁹ m² K/W until reaching a steady state. The minimum ITR was obtained when the bond strength of SAM was close to that of PEG melt. The matching vibrational spectra facilitated the thermal transport between SAM chains and PEG. This work provides helpful information regarding the optimized design of SAM to enhance interfacial thermal transport.