Nanoparticle Behaviour in Complex Media: Methods for Characterizing Physicochemical Properties, Evaluating Protein Corona Formation, and Implications for Biological Studies

A Review for Uncovering the "Protein-Nanoparticle Alliance": Implications of the Protein Corona for Biomedical Applications

Understanding both the physicochemical and biological interactions of nanoparticles is mandatory for the biomedical application of nanomaterials. By binding proteins, nanoparticles acquire new surface identities in biological fluids, the protein corona. Various studies have revealed the dynamic structure and nano-bio interactions of the protein corona. The binding of proteins not only imparts new surface identities to nanoparticles in biological fluids but also significantly influences their bioactivity, stability, and targeting specificity. Interestingly, recent endeavors have been undertaken to harness the potential of the protein corona instead of evading its presence. Exploitation of this 'protein-nanoparticle alliance' has significant potential to change the field of nanomedicine. Here, we present a thorough examination of the latest research on protein corona, encompassing its formation, dynamics, recent developments, and diverse bioapplications. Furthermore, we also aim to explore the interactions at the nano-bio interface, paving the way for innovative strategies to advance the application potential of the protein corona. By addressing challenges and promises in controlling protein corona formation, this review provides insights into the evolving landscape of the 'protein-nanoparticle alliance' and highlights emerging.

Epidermal growth factor alters silica nanoparticle uptake and improves gold-nanoparticle-mediated gene silencing in A549 cells

Introduction

Delivery of therapeutic nanoparticles (NPs) to cancer cells represents a promising approach for biomedical applications. A key challenge for nanotechnology translation from the bench to the bedside is the low amount of administered NPs dose that effectively enters target cells. To improve NPs delivery, several studies proposed NPs conjugation with ligands, which specifically deliver NPs to target cells via receptor binding. One such example is epidermal growth factor (EGF), a peptide involved in cell signaling pathways that control cell division by binding to epidermal growth factor receptor (EGFR). However, very few studies assessed the influence of EGF present in the cell environment, on the cellular uptake of NPs.

Methods

We tested if the stimulation of EGFR-expressing lung carcinomacells A549 with EGF affects the uptake of 59 nm and 422 nm silica (SiO2) NPs. Additionally, we investigated whether the uptake enhancement can be achieved with gold NPs, suitable to downregulate the expression of cancer oncogene c-MYC.

Results

Our findings show that EGF binding to its receptor results in receptor autophosphorylation and initiate signaling pathways, leading to enhanced endocytosis of 59 nm SiO2 NPs, but not 422 nm SiO2 NPs. Additionally, we demonstrated an enhanced gold (Au) NPs endocytosis and subsequently a higher downregulation of c-MYC.

Discussion

These findings contribute to a better understanding of NPs uptake in the presence of EGF and that is a promising approach for improved NPs delivery.

Cellular Uptake of Silica Particles Influences EGFR Signaling Pathway and is Affected in Response to EGF

Background

The human epidermal growth factor receptor (EGFR) is a receptor tyrosine kinase that is involved in several key cellular processes, such as cell proliferation and differentiation, and it has been linked to the development and progression of various cancers (e.g., breast and lung). Researchers have attempted to improve current cancer-targeted therapies by conjugating molecules on the surface of (nano)particles to efficiently target and inhibit EGFR. However, very few in vitro studies have investigated the effect of particles per se on EGFR signaling and dynamics. Furthermore, the impact of concomitant exposure of particles and EGFR ligands, such as epidermal growth factor (EGF) on cellular uptake efficiency has received little attention.

Purpose

The purpose of this research was to determine the effects of silica (SiO₂) particles on EGFR expression and intracellular signaling pathways in A549 lung epithelial cells, in the presence or absence of epidermal growth factor (EGF).

Results

We showed that A549 cells are able to internalize SiO₂ particles with core diameters of 130 nm and 1 µm without affecting cell proliferation or migration. However, both SiO₂ particles interfere with the EGFR signaling pathway by raising the endogenous levels of extracellular signal-regulated kinase (ERK) 1/2. Furthermore, both in the presence and absence of SiO₂ particles, the addition of EGF increased cell migration. EGF also stimulated cellular uptake of 130 nm SiO₂ particles but not 1 µm particles. The increased uptake is primarily associated with EGF-stimulated macropinocytosis.

Conclusion

This study shows that SiO₂ particle uptake interferes with cellular signaling pathways and can be boosted by concurrent exposure to the bioactive molecule EGF. SiO₂ particles, both alone and in combination with the ligand EGF, interfere with EGFR signaling pathway in a size-dependent manner.

Nanoparticles and Vaccine Development

In spite of the progress of conventional vaccines, improvements are required due to concerns about the low immunogenicity of the toxicity, instability, and the need for multiple administrations of the vaccines. To overcome the mentioned problems, nanotechnology has recently been incorporated into vaccine development. Nanotechnology increasingly plays an important role in vaccine development nanocarrier-based delivery systems that offer an opportunity to increase the cellular and humoral immune responses. The use of nanoparticles in vaccine formulations allows not only enhanced immunogenicity and stability of antigen, but also targeted delivery and slow release. Over the past decade, nanoscale size materials such as virus-like particles, liposomes, ISCOMs, polymeric, inorganic nanoparticles and emulsions have gained attention as potential delivery vehicles for vaccine antigens, which can both stabilize vaccine antigens and act as adjuvants. This advantage is attributable to the nanoscale particle size, which facilitates uptake by Antigen- Presenting Cells (APCs), then leading to efficient antigen recognition and presentation. Modifying the surfaces of nanoparticles with different targeting moieties permits the delivery of antigens to specific receptors on the cell surface, thereby stimulating selective and specific immune responses. This review provides an overview of recent advances in nanovaccinology.