Exocytosis of Nanoparticles: A Comprehensive Review

Biotin-functionalized nanoparticles: an overview of recent trends in cancer detection

Electrochemical bio-sensing is a potent and efficient method for converting various biological recognition events into voltage, current, and impedance electrical signals. Biochemical sensors are now a common part of medical applications, such as detecting blood glucose levels, detecting food pathogens, and detecting specific cancers. As an exciting feature, bio-affinity couples, such as proteins with aptamers, ligands, paired nucleotides, and antibodies with antigens, are commonly used as bio-sensitive elements in electrochemical biosensors. Biotin-avidin interactions have been utilized for various purposes in recent years, such as targeting drugs, diagnosing clinically, labeling immunologically, biotechnology, biomedical engineering, and separating or purifying biomolecular compounds. The interaction between biotin and avidin is widely regarded as one of the most robust and reliable noncovalent interactions due to its high bi-affinity and ability to remain selective and accurate under various reaction conditions and bio-molecular attachments. More recently, there have been numerous attempts to develop electrochemical sensors to sense circulating cancer cells and the measurement of intracellular levels of protein thiols, formaldehyde, vitamin-targeted polymers, huwentoxin-I, anti-human antibodies, and a variety of tumor markers (including alpha-fetoprotein, epidermal growth factor receptor, prostate-specific Ag, carcinoembryonic Ag, cancer antigen 125, cancer antigen 15-3, etc.). Still, the non-specific binding of biotin to endogenous biotin-binding proteins present in biological samples can result in false-positive signals and hinder the accurate detection of cancer biomarkers. This review summarizes various categories of biotin-functional nanoparticles designed to detect such biomarkers and highlights some challenges in using them as diagnostic tools.

Primary Human Breast Cancer-Associated Endothelial Cells Favor Interactions with Nanomedicines

Cancer nanomedicines predominately rely on transport processes controlled by tumor-associated endothelial cells to deliver therapeutic and diagnostic payloads into solid tumors. While the dominant role of this class of endothelial cells for nanoparticle transport and tumor delivery is established in animal models, the translational potential in human cells needs exploration. Using primary human breast cancer as a model, the differential interactions of normal and tumor-associated endothelial cells with clinically relevant nanomedicine formulations are explored and quantified. Primary human breast cancer-associated endothelial cells exhibit up to ≈2 times higher nanoparticle uptake than normal human mammary microvascular endothelial cells. Super-resolution imaging studies reveal a significantly higher intracellular vesicle number for tumor-associated endothelial cells, indicating a substantial increase in cellular transport activities. RNA sequencing and gene expression analysis indicate the upregulation of transport-related genes, especially motor protein genes, in tumor-associated endothelial cells. Collectively, the results demonstrate that primary human breast cancer-associated endothelial cells exhibit enhanced interactions with nanomedicines, suggesting a potentially significant role for these cells in nanoparticle tumor delivery in human patients. Engineering nanoparticles that leverage the translational potential of tumor-associated endothelial cell-mediated transport into human solid tumors may lead to the development of safer and more effective clinical cancer nanomedicines.

Effects of Different Surface Functionalizations of Silica Nanoparticles on Mesenchymal Stem Cells

Physicochemical properties of nanoparticles, such as particle size, surface charge, and particle shape, have a significant impact on cell activities. However, the effects of surface functionalization of nanoparticles with small chemical groups on stem cell behavior and function remain understudied. Herein, we incorporated different chemical functional groups (amino, DETA, hydroxyl, phosphate, and sulfonate with charges of +9.5, + 21.7, -14.1, -25.6, and -37.7, respectively) to the surface of inorganic silica nanoparticles. To trace their effects on mesenchymal stem cells (MSCs) of rat bone marrow, these functionalized silica nanoparticles were used to encapsulate Rhodamine B fluorophore dye. We found that surface functionalization with positively charged and short-chain chemical groups facilitates cell internalization and retention of nanoparticles in MSCs. The endocytic pathway differed among functionalized nanoparticles when tested with ion-channel inhibitors. Negatively charged nanoparticles mainly use lysosomal exocytosis to exit cells, while positively charged nanoparticles can undergo endosomal escape to avoid scavenging. The cytotoxic profiles of these functionalized silica nanoparticles are still within acceptable limits and tolerable. They exerted subtle effects on the actin cytoskeleton and migration ability. Last, phosphate-functionalized nanoparticles upregulate osteogenesis-related genes and induce osteoblast-like morphology, implying that it can direct MSCs lineage specification for bone tissue engineering. Our study provides insights into the rational design of biomaterials for effective drug delivery and regenerative medicine.

Cytotoxicity of vanadium dioxide nanoparticles to human embryonic kidney cell line: Compared with vanadium(IV/V) ions

Vanadium dioxide (VO2) is a class of thermochromic material with potential applications in various fields. Massive production and wide application of VO2 raise the concern of its potential toxicity to human, which has not been fully understood. Herein, a commercial VO2 nanomaterial (S-VO2) was studied for its potential toxicity to human embryonic kidney cell line HEK293, and two most common vanadium ions, V(IV) and V(V), were used for comparison to reveal the related mechanism. Our results indicate that S-VO2 induces dose-dependent cellular viability loss mainly through the dissolved V ions of S-VO2 outside the cell rather than S-VO2 particles inside the cell. The dissolved V ions of S-VO2 overproduce reactive oxygen species to trigger apoptosis and proliferation inhibition via several signaling pathways of cell physiology, such as MAPK and PI3K-Akt, among others. All bioassays indicate that the differences in toxicity between S-VO2, V(IV), and V(V) in HEK293 cells are very small, supporting that the toxicity is mainly due to the dissolved V ions, in the form of V(V) and/or V(IV), but the V(V)'s behavior is more similar to S-VO2 according to the gene expression analysis. This study reveals the toxicity mechanism of nanosized VO2 at the molecular level and the role of dissolution of VO2, providing valuable information for safe applications of vanadium oxides.

Size-Related Pathway Flux Analysis of Ultrasmall Iron Oxide Nanoparticles in Macrophage Cell RAW264.7 for Safety Evaluation

The endocytosis, intracellular transport, and exocytosis of different-sized nanoparticles were reported to greatly affect their efficacy and biosafety. The quantitation of endocytosis and exocytosis as well as subcellular distribution of nanoparticles might be an effective approach based on transport pathway flux analysis. Thus, the key parameters that could present the effects of three different-sized ultrasmall iron oxide nanoparticles (USIONPs) were systematically investigated in RAW264.7 cells. The endocytosis and exocytosis of USIONPs were related to their sizes; 15.4 nm of S2 could be quickly and more internalized and excreted in comparison to S1 (7.8 nm) and S3 (30.7 nm). In RAW264.7 cells, USIONPs were observed in endosomes, lysosomes, the Golgi apparatus, and autophagosomes via a transmission electron microscope. Based on flux analysis of intracellular transport pathways of USIONPs, it was found that 43% of S1, 40% of S2, and 44% of S3 were individually transported extracellularly through the Golgi apparatus-involved middle-fast pathway, while 24% of S1, 23% of S2, and 26% of S3 were transported through the fast recycling endosomal pathway, and the residues were transported through the slower speed lysosomal pathway. USIONPs might be transported via size-related endocytosis and exocytosis pathways. The pathway flux could be calculated on the basis of disturbance analysis of special transporters as well as their coding genes. Because there were rate differences among these transport pathways, this pathway flux could anticipate the intracellular remaining time and distribution of different-sized nanoparticles, the function exertion, and side effects of nanomaterials. The size of the nanomaterials could be optimized for improving functions and safety.