Endocytosis-driven gold nanoparticle fractal rearrangement in cells and its influence on photothermal conversion

Finite element modeling of plasmonic resonances in photothermal gold nanoparticles embedded in cells

The use of plasmonic nanoparticles in performing photothermal treatments in cancer cells requires a full knowledge about their optical properties. The surface plasmon resonance is easily foreseen and measurable in colloidal suspensions, however it can be strongly modified when located inside cells. Assessing the optical behavior of plasmonic nanoparticles in cells is essential for an efficient and controlled treatment. This requires the combination of experimental data and computational models to understand the mechanisms that cause the change in their optical response. In this work, we investigate the plasmonic response of Au nanospheres (AuNSs) internalized into cancer cells (MCF-7). Experimental data are compared to the simulations provided by a 3D model based on a finite element method. We demonstrate the impact of physical parameters such as the type of NS assembly, the surrounding medium and the interparticle gap, in the photothermal efficiency of AuNSs. Results open the avenue to predict, by numerical calculations, the optical properties of plasmonic nanoparticles inside cells to minimize treatment costs and times in photothermal therapies.

Monitoring lipopolysaccharide-induced macrophage polarization by surface-enhanced Raman scattering

Macrophages are among the most important components of the innate immune system where the interaction of pathogens and their phagocytosis occur as the first barrier of immunity. When nanomaterials interact with the human body, they have to face macrophages as well. Thus, understanding of nanomaterials-macrophage interactions and underlying mechanisms is crucial. For this purpose, various methods are used. In this study, surface-enhanced Raman scattering (SERS) is proposed by studying lipopolysaccharide (LPS) induced macrophage polarization using gold nanoparticles (AuNPs) as an alternative to the current approaches. For this purpose, the murine macrophage cell line, RAW 264.7 cells, was polarized by LPS, and polarization mechanisms were characterized by nitrite release and reactive oxygen species (ROS) formation and monitored using SERS. The spectral changes were interpreted based on the molecular pathways induced by LPS. Furthermore, polarized macrophages by LPS were exposed to the toxic AuNPs doses to monitor the enhanced phagocytosis and related spectral changes. It was observed that LPS induced macrophage polarization and enhanced AuNP phagocytosis by activated macrophages elucidated clearly from SERS spectra in a label-free non-destructive manner.

Gold Nanoparticles in Neurological Diseases: A Review of Neuroprotection

This review explores the diverse applications of gold nanoparticles (AuNPs) in neurological diseases, with a specific focus on Alzheimer's disease (AD), Parkinson's disease (PD), and stroke. The introduction highlights the pivotal role of neuroinflammation in these disorders and introduces the unique properties of AuNPs. The review's core examines the mechanisms by which AuNPs exert neuroprotection and anti-neuro-inflammatory effects, elucidating various pathways through which they manifest these properties. The potential therapeutic applications of AuNPs in AD are discussed, shedding light on promising avenues for therapy. This review also explores the prospects of utilizing AuNPs in PD interventions, presenting a hopeful outlook for future treatments. Additionally, the review delves into the potential of AuNPs in providing neuroprotection after strokes, emphasizing their significance in mitigating cerebrovascular accidents' aftermath. Experimental findings from cellular and animal models are consolidated to provide a comprehensive overview of AuNPs' effectiveness, offering insights into their impact at both the cellular and in vivo levels. This review enhances our understanding of AuNPs' applications in neurological diseases and lays the groundwork for innovative therapeutic strategies in neurology.

Photonic and magnetic materials for on-demand local drug delivery

Nanomedicine has been considered a promising tool for biomedical research and clinical practice in the 21st century because of the great impact nanomaterials could have on human health. The generation of new smart nanomaterials, which enable time- and space-controlled drug delivery, improve the limitations of conventional treatments, such as non-specific targeting, poor biodistribution and permeability. These smart nanomaterials can respond to internal biological stimuli (pH, enzyme expression and redox potential) and/or external stimuli (such as temperature, ultrasound, magnetic field and light) to further the precision of therapies. To this end, photonic and magnetic nanoparticles, such as gold, silver and iron oxide, have been used to increase sensitivity and responsiveness to external stimuli. In this review, we aim to report the main and most recent systems that involve photonic or magnetic nanomaterials for external stimulus-responsive drug release. The uniqueness of this review lies in highlighting the versatility of integrating these materials within different carriers. This leads to enhanced performance in terms of in vitro and in vivo efficacy, stability and toxicity. We also point out the current regulatory challenges for the translation of these systems from the bench to the bedside, as well as the yet unresolved matter regarding the standardization of these materials.

Prospecting Cellular Gold Nanoparticle Biomineralization as a Viable Alternative to Prefabricated Gold Nanoparticles

Gold nanoparticles (GNPs) have shown considerable potential in a vast number of biomedical applications. However, currently there are no clinically approved injectable GNP formulations. Conversely, gold salts have been used in the clinic for nearly a century. Further, there is evidence of GNP formation in patients treated with gold salts (i.e., chrysiasis). Recent reports evaluating this phenomenon in human cells and in murine models indicate that the use of gold ions for in situ formation of theranostic GNPs could greatly improve the delivery within dense biological tissues, increase efficiency of intracellular gold uptake, and specificity of GNP formation within cancer cells. These attributes in combination with safe clinical application of gold salts make this process a viable strategy for clinical translation. Here, the first summary of the current knowledge related to GNP biomineralization in mammalian cells is provided along with critical assessment of potential biomedical applications of this newly emergent field.

Efficacy and Immune Response Elicited by Gold Nanoparticle- Based Nanovaccines against Infectious Diseases

The use of nanoparticles for developing vaccines has become a routine process for researchers and pharmaceutical companies. Gold nanoparticles (GNPs) are chemical inert, have low toxicity, and are easy to modify and functionalize, making them an attractive choice for nanovaccine development. GNPs are modified for diagnostics and detection of many pathogens. The biocompatibility and biodistribution properties of GNPs render them ideal for use in clinical settings. They have excellent immune modulatory and adjuvant properties. They have been used as the antigen carrier for the delivery system to a targeted site. Tagging them with antibodies can direct the drug or antigen-carrying GNPs to specific tissues or cells. The physicochemical properties of the GNP, together with its dynamic immune response based on its size, shape, surface charge, and optical properties, make it a suitable candidate for vaccine development. The clear outcome of modulating dendritic cells, T and B lymphocytes, which trigger cytokine release in the host, indicates GNPs' efficiency in combating pathogens. The high titer of IgG and IgA antibody subtypes and their enhanced capacity to neutralize pathogens are reported in multiple studies on GNP-based vaccine development. The major focus of this review is to illustrate the role of GNPs in developing nanovaccines against multiple infectious agents, ranging from viruses to bacteria and parasites. Although the use of GNPs has its shortcomings and a low but detectable level of toxicity, their benefits warrant investing more thought and energy into the development of novel vaccine strategies.

Dynamic alteration of poroelastic attributes as determinant membrane nanorheology for endocytosis of organ specific targeted gold nanoparticles

Background

Efficacy of targeted drug delivery using nanoparticles relies on several factors including the uptake mechanisms such as phagocytosis, macropinocytosis, micropinocytosis and receptor mediated endocytosis. These mechanisms have been studied with respect to the alteration in signaling mechanisms, cellular morphology, and linear nanomechanical properties (NMPs). Commonly employed classical contact mechanics models to address cellular NMPs fail to address mesh like structure consisting of bilayer lipids and proteins of cell membrane. To overcome this technical challenge, we employed poroelastic model which accounts for the biphasic nature of cells including their porous behavior exhibiting both solid like (fluid storage) and liquid like (fluid dissipate) behavior.

Results

In this study, we employed atomic force microscopy to monitor the influence of surface engineering of gold nanoparticles (GNPs) to the alteration of nonlinear NMPs such as drained Poisson’s ratio, effective shear stress, diffusion constant and pore dimensions of cell membranes during their uptake. Herein, we used pancreatic cancer (PDAC) cell lines including Panc1, AsPC-1 and endothelial cell (HUVECs) to understand the receptor-dependent and -independent endocytosis of two different GNPs derived using plectin-1 targeting peptide (PTP-GNP) and corresponding scrambled peptide (sPEP-GNP). Compared to untreated cells, in case of receptor dependent endocytosis of PTP-GNPs diffusion coefficient altered ~ 1264-fold and ~ 1530-fold and pore size altered ~ 320-fold and ~ 260-fold in Panc1 and AsPC-1 cells, respectively. Whereas for receptor independent mechanisms, we observed modest alteration in diffusion coefficient and pore size, in these cells compared to untreated cells. Effective shear stress corresponding to 7.38 ± 0.15 kPa and 20.49 ± 0.39 kPa in PTP-GNP treatment in Panc1 and AsPC-1, respectively was significantly more than that for sPEP-GNP. These results demonstrate that with temporal recruitment of plectin-1 during receptor mediated endocytosis affects the poroelastic attributes of the membrane.

Conclusion

This study confirms that nonlinear NMPs of cell membrane are directly associated with the uptake mechanism of nanoparticles and can provide promising insights of the nature of endocytosis mechanism involved for organ specific drug delivery using nanoparticles. Hence, nanomechanical analysis of cell membrane using this noninvasive, label-free and live-cell analytical tool can therefore be instrumental to evaluate therapeutic benefit of nanoformulations.

Graphical Abstract

Supplementary Information

The online version contains supplementary material available at 10.1186/s12951-022-01276-1.

The surface coating of iron oxide nanoparticles drives their intracellular trafficking and degradation in endolysosomes differently depending on the cell type

Magnetic nanoparticles (MNPs) are potential theranostic tools that are biodegraded through different endocytic pathways. However, little is known about the endolysosomal network through which MNPs transit and the influence of the surface coating in this process. Here, we studied the intracellular transit of two MNPs with identical iron oxide core size but with two distinct coatings: 3-aminopropyl-trietoxysilane (APS) and dimercaptosuccinic acid (DMSA). Using endolysosomal markers and a high throughput analysis of the associated proteome, we tracked the MNPs intracellularly in two different mouse cell lines, RAW264.7 (macrophages) and Pan02 (tumor cells). We did not detect differences in the MNP trafficking kinetics nor in the MNP-containing endolysosome phenotype in Pan02 cells. Nonetheless, DMSA-MNPs transited at slower rate than APS-MNPs in macrophages as measured by MNP accumulation in Rab7⁺ endolysosomes. Macrophage DMSA-MNP-containing endolysosomes had a higher percentage of lytic enzymes and catalytic proteins than their APS-MNP counterparts, concomitantly with a V-type ATPase enrichment, suggesting an acidic nature. Consequently, more autophagic vesicles are induced by DMSA-MNPs in macrophages, enhancing the expression of iron metabolism-related genes and proteins. Therefore, unlike Pan02 cells, the MNP coating appears to influence the intracellular trafficking rate and the endolysosome nature in macrophages. These results highlight how the MNP coating can determine the nanoparticle intracellular fate and biodegradation in a cell-type bias.

Tumor-Selective Immune-Active Mild Hyperthermia Associated with Chemotherapy in Colon Peritoneal Metastasis by Photoactivation of Fluorouracil-Gold Nanoparticle Complexes

Peritoneal metastasis (PM) is considered as the terminal stage of metastatic colon cancer, with still poor median survival rate even with the best recent chemotherapy treatment. The current PM treatment combines cytoreductive surgery, which consists of resecting all macroscopic tumors, with hyperthermic intraperitoneal chemotherapy (HIPEC), which uses mild hyperthermia to boost the diffusion and cytotoxic effect of chemotherapeutic drugs. As HIPEC is performed via a closed circulation of a hot liquid containing chemotherapy, it induces uncontrolled heating and drug distribution in the whole peritoneal cavity with important off-site toxicity and a high level of morbidity. Here, we propose a safer precision strategy using near-infrared (NIR) photoactivated gold nanoparticles (AuNPs) coupled to the chemotherapeutic drug 5-fluorouracil (5-FU) to enable a spatial and temporal control of mild chemo-hyperthermia targeted to the tumor nodules within the peritoneal cavity. Both the 16 nm AuNPs and the corresponding complex with 5-FU (AuNP-5-FU) were shown as efficient NIR photothermal agents in the microenvironment of subcutaneous colon tumors as well as PM in syngeneic mice. Noteworthy, NIR photothermia provided additional antitumor effects to 5-FU treatment. A single intraperitoneal administration of AuNP-5-FU resulted in their preferential accumulation in tumor nodules and peritoneal macrophages, allowing light-induced selective hyperthermia, extended tumor necrosis, and activation of a pro-inflammatory immune response while leaving healthy tissues without any damage. From a translational standpoint, the combined and tumor-targeted photothermal and chemotherapy mediated by the AuNP-drug complex has the potential to overcome the current off-target toxicity of HIPEC in clinical practice.