Size-dependent internalisation of folate-decorated nanoparticles via the pathways of clathrin and caveolae-mediated endocytosis in ARPE-19 cells

Contribution of extracellular vesicles for the pathogenesis of retinal diseases: shedding light on blood-retinal barrier dysfunction

Retinal degenerative diseases, including diabetic retinopathy (DR) and age-related macular degeneration (AMD), loom as threats to vision, causing detrimental effects on the structure and function of the retina. Central to understanding these diseases, is the compromised state of the blood-retinal barrier (BRB), an effective barrier that regulates the influx of immune and inflammatory components. Whether BRB breakdown initiates retinal distress, or is a consequence of disease progression, remains enigmatic. Nevertheless, it is an indication of retinal dysfunction and potential vision loss.The intricate intercellular dialogues among retinal cell populations remain unintelligible in the complex retinal milieu, under conditions of inflammation and oxidative stress. The retina, a specialized neural tissue, sustains a ceaseless demand for oxygen and nutrients from two vascular networks. The BRB orchestrates the exchange of molecules and fluids within this specialized region, comprising the inner BRB (iBRB) and the outer BRB (oBRB). Extracellular vesicles (EVs) are small membranous structures, and act as messengers facilitating intercellular communication in this milieu.EVs, both from retinal and peripheral immune cells, increase complexity to BRB dysfunction in DR and AMD. Laden with bioactive cargoes, these EVs can modulate the retinal microenvironment, influencing disease progression. Our review delves into the multifaceted role of EVs in retinal degenerative diseases, elucidating the molecular crosstalk they orchestrate, and their microRNA (miRNA) content. By shedding light on these nanoscale messengers, from their biogenesis, release, to interaction and uptake by target cells, we aim to deepen the comprehension of BRB dysfunction and explore their therapeutic potential, therefore increasing our understanding of DR and AMD pathophysiology.

Advances in liposomes loaded with photoresponse materials for cancer therapy

Cancer treatment is presently a significant challenge in the medical domain, wherein the primary modalities of intervention include chemotherapy, radiation therapy and surgery. However, these therapeutic modalities carry side effects. Photothermal therapy (PTT) and photodynamic therapy (PDT) have emerged as promising modalities for the treatment of tumors in recent years. Phototherapy is a therapeutic approach that involves the exposure of materials to specific wavelengths of light, which can subsequently be converted into either heat or Reactive Oxygen Species (ROS) to effectively eradicate cancer cells. Due to the hydrophobicity and lack of targeting of many photoresponsive materials, the use of nano-carriers for their transportation has been extensively explored. Among these nanocarriers, liposomes have been identified as an effective drug delivery system due to their controllability and availability in the biomedical field. By binding photoresponsive materials to liposomes, it is possible to reduce the cytotoxicity of the material and regulate drug release and accumulation at the tumor site. This article provides a comprehensive review of the progress made in cancer therapy using photoresponsive materials loaded onto liposomes. Additionally, the article discusses the potential synergistic treatment through the combination of phototherapy with chemo/immuno/gene therapy using liposomes.

Surface Modification of Mesoporous Silica Nanoparticles for Application in Targeted Delivery Systems of Antitumour Drugs

The problem of tumour therapy has attracted the attention of many researchers for many decades. One of the promising strategies for the development of new dosage forms to improve oncology treatment efficacy and minimise side effects is the development of nanoparticle-based targeted transport systems for anticancer drugs. Among inorganic nanoparticles, mesoporous silica deserves special attention due to its outstanding surface properties and drug-loading capability. This review analyses the various factors affecting the cytotoxicity, cellular uptake, and biocompatibility of mesoporous silica nanoparticles (MSNs), constituting a key aspect in the development of safe and effective drug delivery systems. Special attention is paid to technological approaches to chemically modifying MSNs to alter their surface properties. The stimuli that regulate drug release from nanoparticles are also discussed, contributing to the effective control of the delivery process in the body. The findings emphasise the importance of modifying MSNs with different surface functional groups, bio-recognisable molecules, and polymers for their potential use in anticancer drug delivery systems.

Overcoming colloidal nanoparticle aggregation in biological milieu for cancer therapeutic delivery: Perspectives of materials and particle design

Nanoparticles as cancer therapeutic carrier fail in clinical translation due to complex biological environments in vivo consisting of electrolytes and proteins which render nanoparticle aggregation and unable to reach action site. This review identifies the desirable characteristics of nanoparticles and their constituent materials that prevent aggregation from site of administration (oral, lung, injection) to target site. Oral nanoparticles should ideally be 75-100 nm whereas the size of pulmonary nanoparticles minimally affects their aggregation. Nanoparticles generally should carry excess negative surface charges particularly in fasting state and exert steric hindrance through surface decoration with citrate, anionic surfactants and large polymeric chains (polyethylene glycol and polyvinylpyrrolidone) to prevent aggregation. Anionic as well as cationic nanoparticles are both predisposed to protein corona formation as a function of biological protein isoelectric points. Their nanoparticulate surface composition as such should confer hydrophilicity or steric hindrance to evade protein corona formation or its formation should translate into steric hindrance or surface negative charges to prevent further aggregation. Unexpectedly, smaller and cationic nanoparticles are less prone to aggregation at cancer cell interface favoring endocytosis whereas aggregation is essential to enable nanoparticles retention and subsequent cancer cell uptake in tumor microenvironment. Present studies are largely conducted in vitro with simplified simulated biological media. Future aggregation assessment of nanoparticles in biological fluids that mimic that of patients is imperative to address conflicting materials and designs required as a function of body sites in order to realize the future clinical benefits.

Investigation of cellular uptake and transport capacity of Cordyceps sinensis exopolysaccharide‑selenium nanoparticles with different particle sizes in Caco-2 cell monolayer

Cordyceps sinensis exopolysaccharide‑selenium nanoparticles (EPS-SeNPs) were successfully constructed, characterized, and its Se release kinetics and mechanism were also evaluated in our previous studies. However, the intestinal cellular uptake and transport capacities of EPS-SeNPs remain unknown. On the basis of our previous researches, this work was designed to evaluate the uptake and transport capacities of EPS-SeNPs (EPS/Se = 20/1, 3/1, 1/1, and 3/4) in intestinal epithelial (Caco-2) cells. Confocal laser scanning microscopy results indicated that the internalization of coumarin-6 labeled EPS-SeNPs was in a time-dependent process and eventually located in the cytoplasm, not in the nucleus. Endocytosis inhibitors were employed to evaluate the cellular uptake pathway of EPS-SeNPs, relevant results revealed that clathrin-, caveolae-, and energy-mediated pathways were participated in the internalization of EPS-SeNPs by Caco-2 cells. In addition, the transportation of EPS-SeNPs across Caco-2 cell monolayers was in a concentration-dependent manner. Different particle sizes of EPS-SeNPs presented different uptake and transport capacities in Caco-2 cells. Noteworthy, EPS/Se = 3/4 with the highest selenium content possessed the most superior cellular uptake and transport abilities in Caco-2 cells. The present work may contribute to illustrate the internalization and transport mechanism of EPS-SeNPs, thus facilitating its application in food and medical industries.

Lipid-based nanocarriers challenging the ocular biological barriers: Current paradigm and future perspectives

Eye is the most specialized and sensory body organ and treating eye diseases efficiently is necessary. Despite various attempts, the design of a consummate ophthalmic drug delivery system remains unsolved because of anatomical and physiological barriers that hinder drug transport into the desired ocular tissues. It is important to advance new platforms to manage ocular disorders, whether they exist in the anterior or posterior cavities. Nanotechnology has piqued the interest of formulation scientists because of its capability to augment ocular bioavailability, control drug release, and minimize inefficacious drug absorption, with special attention to lipid-based nanocarriers (LBNs) because of their cellular safety profiles. LBNs have greatly improved medication availability at the targeted ocular site in the required concentration while causing minimal adverse effects on the eye tissues. Nevertheless, the exact mechanisms by which lipid-based nanocarriers can bypass different ocular barriers are still unclear and have not been discussed. Thus, to bridge this gap, the current work aims to highlight the applications of LBNs in the ocular drug delivery exploring the different ocular barriers and the mechanisms viz. adhesion, fusion, endocytosis, and lipid exchange, through which these platforms can overcome the barrier characteristics challenges.

Exposure to High Dosage of Gold Nanoparticles Accelerates Growth Rate by Modulating Ribosomal Protein Expression

Gold nanoparticles (AuNPs) have been utilized in various biomedical applications including diagnostics and drug delivery. However, the cellular and metabolic responses of cells to these particles remain poorly characterized. In this study, we used bacteria (Escherichia coli and Bacillus subtilis) and a fungus (Saccharomyces cerevisiae) as model organisms to investigate the cellular and metabolic effects of exposure to different concentrations of citrate-capped spherical AuNPs with diameters of 5 and 10 nm. In different growth media, the synthesized AuNPs displayed stability and microorganisms exhibited uniform levels of uptake. Exposure to a high concentration of AuNPs (1012 particles) resulted in a reduced cell division time and a 2-fold increase in cell density in both bacteria and fungus. The exposed cells exhibited a decrease in average cell size and an increase in the expression of FtsZ protein (cell division marker), further supporting an accelerated growth rate. Notably, exposure to such a high concentration of AuNPs did not induce DNA damage, envelope stress, or a general stress response in bacteria. Differential whole proteome analysis revealed modulation of ribosomal protein expression upon exposure to AuNPs in both E. coli and S. cerevisiae. Interestingly, the accelerated growth observed upon exposure to AuNPs was sensitive to sub-minimum inhibitory concentration (sub-MIC) concentration of drugs that specifically target ribosome assembly and recycling. Based upon these findings, we hypothesize that exposure to high concentrations of AuNPs induces stress on the translation machinery. This leads to an increase in the protein synthesis rate by modulating ribosome assembly, which results in the rapid proliferation of cells.

Internalization of Angiotensin-(1-12) in Adult Retinal Pigment Epithelial-19 Cells

Purpose: Angiotensin-(1-12) [Ang-(1-12)] serves as a primary substrate to generate angiotensin II (Ang II) by angiotensin-converting enzyme and/or chymase suggests it may be an unrecognized source of Ang II-mediated microvascular complication in hypertension-mediated retinopathy. We investigated Ang-(1-12) expression and internalization in adult retinal pigment epithelial-19 (ARPE-19) cultured cells. We performed the internalization of Ang-(1-12) in ARPE-19 cells in the presence of a highly specific monoclonal antibody (mAb) developed against the C-terminal end of the Ang-(1-12) sequence. Methods: All experiments were performed in confluent ARPE-19 cells (passage 28-35). We employed high-performance liquid chromatography to purify radiolabeled, 125I-Ang-(1-12) and immuno-neutralization with Ang-(1-12) mAb to demonstrate Ang-(1-12)'s internalization in ARPE-19 cells. Internalization was also demonstrated by immunofluorescence (IF) method. Results: These procedures revealed internalization of an intact 125I-Ang-(1-12) in ARPE-19 cells. A significant reduction (∼53%, P < 0.0001) in 125I-Ang-(1-12) internalization was detected in APRE-19 cells in the presence of the mAb. IF staining experiments further confirms internalization of Ang-(1-12) into the cells from the extracellular culture medium. No endogenous expression was detected in the ARPE-19 cells. An increased intensity of IF staining was detected in cells exposed to 1.0 μM Ang-(1-12) compared with 0.1 μM. Furthermore, we found hydrolysis of Ang-(1-12) into Ang II by ARPE-19 cells' plasma membranes. Conclusions: Intact Ang-(1-12) peptide is internalized from the extracellular spaces in ARPE-19 cells and metabolized into Ang II. The finding that a selective mAb blocks cellular internalization of Ang-(1-12) suggests alternate therapeutic approaches to prevent/reduce the RPE cells Ang II burden.

Influence of Folate-Targeted Gold Nanoparticles on Subcellular Localization and Distribution into Lysosomes

The cell interaction, mechanism of cell entry and intracellular fate of surface decorated nanoparticles are known to be affected by the surface density of targeting agents. However, the correlation between nanoparticles multivalency and kinetics of the cell uptake process and disposition of intracellular compartments is complicated and dependent on a number of physicochemical and biological parameters, including the ligand, nanoparticle composition and colloidal properties, features of targeted cells, etc. Here, we have carried out an in-depth investigation on the impact of increasing folic acid density on the kinetic uptake process and endocytic route of folate (FA)-targeted fluorescently labelled gold nanoparticles (AuNPs). A set of AuNPs (15 nm mean size) produced by the Turkevich method was decorated with 0–100 FA-PEG3.5kDa-SH molecules/particle, and the surface was saturated with about 500 rhodamine-PEG2kDa-SH fluorescent probes. In vitro studies carried out using folate receptor overexpressing KB cells (KBFR-high) showed that the cell internalization progressively increased with the ligand surface density, reaching a plateau at 50:1 FA-PEG3.5kDa-SH/particle ratio. Pulse-chase experiments showed that higher FA density (50 FA-PEG3.5kDa-SH molecules/particle) induces more efficient particle internalization and trafficking to lysosomes, reaching the maximum concentration in lysosomes at 2 h, than the lower FA density of 10 FA-PEG3.5kDa-SH molecules/particle. Pharmacological inhibition of endocytic pathways and TEM analysis showed that particles with high folate density are internalized predominantly by a clathrin-independent process.

Responsive Nanostructure for Targeted Drug Delivery

Currently, intelligent, responsive biomaterials have been widely explored, considering the fact that responsive biomaterials provide controlled and predictable results in various biomedical systems. Responsive nanostructures undergo reversible or irreversible changes in the presence of a stimulus, and that stimuli can be temperature, a magnetic field, ultrasound, pH, humidity, pressure, light, electric field, etc. Different types of stimuli being used in drug delivery shall be explained here. Recent research progress in the design, development and applications of biomaterials comprising responsive nanostructures is also described here. More emphasis will be given on the various nanostructures explored for the smart stimuli responsive drug delivery at the target site such as wound healing, cancer therapy, inflammation, and pain management in order to achieve the improved efficacy and sustainability with the lowest side effects. However, it is still a big challenge to develop well-defined responsive nanostructures with ordered output; thus, challenges faced during the design and development of these nanostructures shall also be included in this article. Clinical perspectives and applicability of the responsive nanostructures in the targeted drug delivery shall be discussed here.

4-Iodo-6-phenylpyrimidine (4-IPP) suppresses fibroblast-like synoviocyte- mediated inflammation and joint destruction associated with rheumatoid arthritis

Rheumatoid arthritis (RA) is a systemic immune-mediated inflammatory disease that significantly impacts patients' quality of life. Fibroblast-like synovial cells (FLSs) within the synovial intima exhibit "tumor-like" properties such as increased proliferation, migration, and invasion. Activation of FLSs and secretion of pro-inflammation factors result in pannus formation and cartilage destruction. As an inhibitor of the cytokine, macrophage migration inhibitory factor (MIF), 4-Iodo-6-phenylpyrimidine (4-IPP) has been shown to reduce cell proliferation, migration, invasion, and the secretion of pro-inflammatory mediators in a variety of diseases. However, the usefulness of 4-IPP for RA treatment has not been assessed and was the purpose of this study. In vitro, 4-IPP was demonstrated to inhibit proliferation, migration, and invasion of RA FLSs, as well as the expression of pro-inflammatory cytokines. 4-IPP was also shown to inhibit MIF-induced phosphorylation of ERK, JNK, and p38, as well as reduce expression of COX2 and PGE2. In order to efficiently deliver 4-IPP to anatomical RA sites, we developed lactic-co-glycolic acid (PLGA) nanospheres, which not only protected 4-IPP from degradation but also controlled the release of 4-IPP. 4-IPP/PLGA nanospheres had potent anti-inflammatory activity and a high degree of biosafety. Results showed that local 4-IPP concentration was increased by nanosphere delivery, effectively reducing the inflammatory microenvironment as well as synovial inflammation, joint swelling, and cartilage destruction in a collagen-induced rheumatoid arthritis (CIA) rat model. Therefore, 4-IPP nanospheres are a sustained-release delivery system that may be an effective therapeutic strategy for RA treatment.

Ocular barriers as a double-edged sword: preventing and facilitating drug delivery to the retina

In recent decades, the growing of the aging population in the world brings increasingly heavy burden of vision-threatening retinal diseases. One of the biggest challenges in the treatment of retinal diseases is the effective drug delivery to the diseased area. Due to the existence of multiple anatomical and physiological barriers of the eye, commonly used oral drugs or topical eye drops cannot effectively reach the retinal lesions. Innovations in new drug formulations and delivery routes have been continuously applied to improve current drug delivery to the back of the eye. Unique ocular anatomical structures or physiological activities on these ocular barriers, in turn, can facilitate drug delivery to the retina if compatible formulations or delivery routes are properly designed or selected. This paper focuses on key barrier structures of the eye and summarizes advances of corresponding drug delivery means to the retina, including various local drug delivery routes by invasive approaches, as well as systemic eye drug delivery by non-invasive approaches.

Molecular Docking and Intracellular Translocation of Extracellular Vesicles for Efficient Drug Delivery

Extracellular vesicles (EVs), including exosomes, mediate intercellular communication by delivering their contents, such as nucleic acids, proteins, and lipids, to distant target cells. EVs play a role in the progression of several diseases. In particular, programmed death-ligand 1 (PD-L1) levels in exosomes are associated with cancer progression. Furthermore, exosomes are being used for new drug-delivery systems by modifying their membrane peptides to promote their intracellular transduction via micropinocytosis. In this review, we aim to show that an efficient drug-delivery system and a useful therapeutic strategy can be established by controlling the molecular docking and intracellular translocation of exosomes. We summarise the mechanisms of molecular docking of exosomes, the biological effects of exosomes transmitted into target cells, and the current state of exosomes as drug delivery systems.

Platelet membrane-camouflaged nanoparticles carry microRNA inhibitor against myocardial ischaemia‒reperfusion injury

The incidence of myocardial ischaemia‒reperfusion injury (MIRI) is increasing every year, and there is an urgent need to develop new therapeutic approaches. Nrf2 is thought to play a protective role during MIRI and it is regulated by microRNAs (miRNAs). This study focused on PLGA nanoparticles camouflaged by platelet membrane vesicles (PMVs) (i.e., PMVs@PLGA complexes) carrying microRNA inhibitors, which regulate Nrf2 and can play a therapeutic role in the MIRI process. In vitro and in vivo characterization showed that PMVs@PLGA has excellent transfection efficiency, low toxicity and good targeting. MicroRNAs that effectively regulate Nrf2 were identified, and then PMVs@PLGA-miRNA complexes were prepared and used for in vitro and in vivo treatment. PMVs@PLGA-miRNA complexes can effectively target the delivery of inhibitors to cardiomyocytes. Our results suggest that PMVs@PLGA complexes are a novel delivery system and a novel biological approach to the treatment of MIRI.

Baicalein Loaded Crown Ether-mPEG-PLGA Micelle Drug Delivery System for Increased Breast Cancer Treatment: Preparation, Characterization, In-Vitro and In-Vivo Evaluations

Due to low aqueous solubility and poor bioavailability of the flavone baicalein (BIC), a nano-micelle of delivery system was developed. Preparation of BIC-loaded crown ether-mPEG-PLGA micelle (BCPP-M) was performed via thin-film hydration method. Characterization of micellar excipients was accomplished with 1H NMR, while evaluation of the optimal BCPP-M formulation was appropriately carried out through zeta potential (ZP), size of particles (PS), efficiency of encapsulation (EE) and capacity of drug loading (DL). We evaluated BIC release In-Vitro and profile of In-Vivo pharmacokinetics. Evaluation of the anti-breast cancer property of BCPP-M using MCP-7 cells cytotoxicity and mice model was performed. Particles of BCPP-M were homogenously and spherically shaped with smaller average PS, coupled with higher EE and DL, good stability and polydispersity index (PDI). The accumulative release of BCPP-M was obviously higher than free-BIC. Significantly, oral biological availability of BCPP-M was improved comparable to free BIC. Besides, half maximum inhibitory concentration (IC50) of BCPP-M in MCP-7 cells was lower than free-BIC. Animal experiments also showed targeting, long circulation and antitumor potential of BCPP-M. Successful incorporation of BIC into long-acting and targeting micellar system could have enhanced solubility in aqueous media, oral In-Vivo availability and antitumor property of BIC.

Chitosan-alginate nanoparticles of cabazitaxel: Design, dual-receptor targeting and efficacy in lung cancer model

Cabazitaxel (CZT) loaded chitosan-alginate based (CSA) nanoparticles were developed with dual targeting functions of both folate receptor and epidermal growth factor receptor (EGFR) using ionic gelation technique. The chitosan-folate conjugate was synthesized, and characterized by using FTIR, NMR and Mass spectroscopy. The physicochemical parameters and morphology of all CSA nanoparticles were examined. The degree of conjugation of folic acid and cetuximab (CTXmab) was determined by UV-Visible spectroscopy and Bradford assay, respectively. Moreover, XPS analysis also supported the presence of the ligands on nanoparticles. The cellular-uptake study performed on A-549 cells demonstrated a significant enhancement in the uptake of dual-receptor targeted CSA nanoparticles than non-targeted and single-receptor targeted CSA nanoparticles. Further, CZT-loaded dual receptors targeted CSA nanoparticles also showed significantly lower IC₅₀ values (~38 folds) than the CZT control against A-549 cells. Further, in-vivo histopathological evaluations of dual receptor-targeted CSA nanoparticles have demonstrated better safety in Wistar rats. Moreover, its treatment on the Benzo(a)pyrene (B(a)P) induced lung cancer mice model has showed the enhanced anticancer efficacy of CZT with a prolonged survival rate.

Modulating Fingolimod (FTY720) Anti-SARS-CoV-2 Activity Using a PLGA-Based Drug Delivery System

COVID-19 has resulted in more than 490 million people being infected worldwide, with over 6 million deaths by April 05th, 2022. Even though the development of safe vaccine options is an important step to reduce viral transmission and disease progression, COVID-19 cases will continue to occur, and for those cases, efficient treatment remains to be developed. Here, a drug repurposing strategy using nanotechnology is explored to develop a therapy for COVID-19 treatment. Nanoparticles (NPs) based on PLGA for fingolimod (FTY720) encapsulation show a size of ∼150 nm and high drug entrapment (∼90%). The NP (NP@FTY720) can control FTY720 release in a pH-dependent manner. Cytotoxicity assays using different cell lines show that NP@FTY720 displays less toxicity than the free drug. Flow cytometry and confocal microscopy reveal that NPs are actively internalized mostly through caveolin-mediated endocytosis and macropinocytosis pathways and co-localized with lysosomes. Finally, NP@FTY720 not only exhibits anti-SARS-CoV-2 activity at non-cytotoxic concentrations, but its biological potential for viral infection inhibition is nearly 70 times higher than that of free drug treatment. Based on these findings, the combination of drug repurposing and nanotechnology as NP@FTY720 is presented for the first time and represents a promising frontline in the fight against COVID-19.

The endocytosis of nano-Pt into non-small cell lung cancer H1299 cells and intravital therapeutic effect in vivo

Lung cancer remains the most common fatal malignant disease, and the 5-year survival rate of patients with metastasis is merely 6%. In this research, the platinum nanocluster (short for nano-Pt) was used for optical imaging without the help of other fluorescent probes and possess targeted antitumor activity as well as low systemic toxicity. The endocytic pathway and distribution of nano-Pt in non-small cell lung cancer NSCLC H1299 cells was explored by the means of quantitative and qualitative tests. Furthermore, the targeting capability and antitumor efficiency of nano-Pt was detected by intravital imaging experiment and antitumor experiment. The research implies that nano-Pt entered H1299 cells dominatingly through macropinocytosis and clathrin-dependent endocytosis pathway, and has significant antitumor efficiency, targeting properties and reliable safety for mouse tumor, indicating this nano-Pt has great potential for clinical diagnosis and therapy of NSCLC H1299 cells.

Therapeutic implications of nanodrug and tissue engineering for retinal pigment epithelium-related diseases

The retinal pigment epithelium (RPE), as a single layer of cells that performs multiple functions posteriorly in the eye, is a promising target site for the prevention and treatment of several clinical diseases, including proliferative diabetic retinopathy, age-related macular degeneration, chorionic neovascularization, and retinitis pigmentosa. In recent decades, several nanodrug delivery platforms and tissue-engineered RPE have been widely developed to treat RPE-related diseases. This work summarizes the recent advances in nanoplatforms and tissue engineering scaffolds developed in these fields. The diseases associated with pathological RPE and their common therapy strategies are first introduced. Then, the recent progress made with a variety of drug delivery systems is presented, with an emphasis on the modification strategies of nanomaterials for targeted delivery. Tissue engineering-mediated RPE transplantation for treating these diseases is subsequently described. Finally, the clinical translation challenges in these fields are discussed in depth. This article will offer readers a better understanding of emerging nanotechnology and tissue engineering related to the treatment of RPE-related diseases and could facilitate their widespread use in experiments in vivo and in clinical applications.

The Effect of Particle Size on the Absorption of Cyclosporin A Nanosuspensions

Background

Cyclosporin A (CsA) is a hydrophobic drug widely used as an immunosuppressant and anti-rejection drug in solid organ transplantation. On the market, there are two oral CsA formulations available containing polyoxyethylene castor oil, which can cause serious allergic reactions and nephrotoxicity. In order to eliminate polyoxyethylene castor oil, CsA was formulated into a nanosuspension. This study aimed to design an oral cyclosporin A nanosuspensions (CsA-NSs) and investigate the effect of particle size on absorption of CsA-NSs.

Methods

CsA-NSs were prepared using a wet bead milling method. Particle size, morphology and crystallinity state of CsA-NSs were characterized. The in vitro dissolution, the intestinal absorption properties and pharmacokinetic study of CsA-NSs were investigated.

Results

CsA-NSs with sizes of 280 nm, 522 nm and 2967 nm were prepared. The shape of CsA-NSs with smaller size was similar to that of spheres. The crystallinity of CsA in nanocrystals was reduced. The dissolution rate of CsA-NSs (280 nm) was greater than that of CsA-NSs (522 nm) and CsA-NSs (2967 nm). CsA-NSs (280 nm) showed higher absorption rate constants (K_α) and effective permeability coefficients (P_eff) of different intestinal segments compared with that of CsA-NSs (522 nm) and CsA-NSs (2967 nm). AUC_0-48h of 280 nm CsA-NSs was about 1.12-fold of that of 522 nm CsA-NSs, and about 1.51-fold of that of 2967 nm CsA-NSs. In particular, the particle size of CsA-NSs was nanoscale, and their bioavailability was bioequivalent with marked self-microemulsion (Sandimmun Neoral^®).

Conclusion

It is feasible to prepare CsA-NSs. The dissolution rate, gastrointestinal transport properties and the oral absorption of CsA-NSs were promoted by reducing size. Considering the cost, efficiency and energy consumption, there should be an optimal particle size range in industrial production.

Direct nose to the brain nanomedicine delivery presents a formidable challenge

This advanced review describes the anatomical and physiological barriers and mechanisms impacting nanomedicine translocation from the nasal cavity directly to the brain. There are significant physiological and anatomical differences in the nasal cavity, olfactory area, and airflow reaching the olfactory epithelium between humans and experimentally studied species that should be considered when extrapolating experimental results to humans. Mucus, transporters, and tight junction proteins present barriers to material translocation across the olfactory epithelium. Uptake of nanoparticles through the olfactory mucosa and translocation to the brain can be intracellular via cranial nerves (intraneuronal) or other cells of the olfactory epithelium, or extracellular along cranial nerve pathways (perineural) and surrounding blood vessels (perivascular, the glymphatic system). Transport rates vary greatly among the nose to brain pathways. Nanomedicine physicochemical properties (size, surface charge, surface coating, and particle stability) can affect uptake efficiency, which is usually less than 5%. Incorporation of therapeutic agents in nanoparticles has been shown to produce pharmacokinetic and pharmacodynamic benefits. Assessment of adverse effects has included olfactory mucosa toxicity, ciliotoxicity, and olfactory bulb and brain neurotoxicity. The results have generally suggested the investigated nanomedicines do not present significant toxicity. Research needs to advance the understanding of nanomedicine translocation and its drug cargo after intranasal administration is presented. This article is categorized under: Therapeutic Approaches and Drug Discovery > Nanomedicine for Neurological Disease Therapeutic Approaches and Drug Discovery > Emerging Technologies Toxicology and Regulatory Issues in Nanomedicine > Toxicology of Nanomaterials.

Delivery of small interfering RNAs by nanovesicles for cancer therapy

Small interfering ribonucleic acids (siRNAs) are originally recognized as an intermediate of the RNA interference (RNAi) pathway. They can inhibit or silence various cellular pathways by knocking down specific messenger RNA molecules. In cancer cells, siRNAs can suppress the expression of several multidrug-resistant genes, leading to the increased deposition of chemotherapeutic drugs at the tumor site. siRNA therapy can be used to selectively increase apoptosis of cancer cells or activate an immune response to the cancer. However, delivering siRNAs to the targeted location is the main limitation in achieving safe and effective delivery of siRNAs. This review highlights some representative examples of nonviral delivery systems, especially nanovesicles such as exosomes, liposomes, and niosomes. Nanovesicles can improve the delivery of siRNAs by increasing their intracellular delivery, and they have demonstrated excellent potential for cancer therapy. This review focuses on recent discoveries of siRNA targets for cancer therapy and the use of siRNAs to successfully silence these targets. In addition, this review summarizes the recent progress in designing nanovesicles (liposomes or niosomes) for siRNA delivery to cancer cells and the effects of a combination of anticancer drugs and siRNA therapy in cancer therapy.

Effects of nanoparticle-mediated Co-delivery of bFGF and VEGFA genes to deep burn wounds: An in vivo study

Deep burns are a common form of trauma worldwide, and they are hard to be cured in a short time and enhance psychological pressure of the patients. How to effectively promote the healing of wounds after burns is a continuing challenge currently faced by burn physicians. Various strategies of promoting wound healing of deep burns have been developed, including gene therapy and growth factor therapy. In this study, we developed a combined therapy using PLGA nanoparticles as carriers to deliver bFGF and VEGFA genes to promote healing of burn wounds. We first inserted the bFGF and VEGFA genes into pEGFP-N1 vectors and loaded the mixed generated plasmids into PLGA nanoparticles. Next, we injected the nanoparticle/plasmid complexes into the rats intracutaneously and found that the complexes were successfully transfected in vivo one week later. Finally, we injected the nanoparticle/plasmid complexes containing bFGF and VEGFA around burn wounds. We found that the percentage of wound healing of rats treated with nanoparticles/bFGF+ VEGFA plasmid complexes was higher than that of rats in the scald control group, and the early percentage of wound complete epithelialization was also higher. Therefore, combining gene therapy with nanoparticles may be an effective biological strategy for wound repair.

Glimpse into Cellular Internalization and Intracellular Trafficking of Lipid-Based Nanoparticles in Cancer Cells

Lipid-based nanoparticles as drug delivery carriers have been mainly used for delivery of anti-cancer therapeutic agents. Lipid-based nanoparticles, due to their smaller particle size and similarity to cell membranes, are readily internalized into cancer cells. Interestingly, cancer cells also overexpress receptors for specific ligands including folic acid, hyaluronic acid, and transferrin on their surface. This allows the use of these ligands for surface modification of the lipid-based nanoparticle. These modifications then allow the specific recognition of these ligand-coated nanoparticles by their receptors on cancer cells allowing the targeted gradual intracellular accumulation of the functionalized nanoplatforms. These interactions could eventually enhance the internalization of desired drugs via increasing ligand-receptor mediated cellular uptake of the nanoplatforms. The cellular internalization of the nanoplatforms also varies and depends on their physicochemical properties including particle size, zeta potential, and shape. The cellular uptake is also influenced by the types of ligand internalization pathway utilized by cells such as phagocytosis, macropinocytosis, and multiple endocytosis pathways. In this review, we will classify and discuss lipid based nanoparticles engineered to express specific ligands, and are recognized by their receptors on cancer cell, and their cellular internalization pathways. Moreover, the intracellular fate of nanoparticles decorated with specific ligands and the best internalization pathways (caveolae mediated endocytosis) for safe cargo delivery will be discussed.

When metal-organic framework mediated smart drug delivery meets gastrointestinal cancers

Cancers of the gastrointestinal tract constitute one of the most common cancer types worldwide and a ∼58% increase in the global number of cases has been estimated by IARC for the next twenty years. Recent advances in drug delivery technologies have attracted scientific interest for developing and utilizing efficient therapeutic systems. The present review focuses on the use of nanoscale MOFs (Nano-MOFs) as carriers for drug delivery and imaging purposes. In pursuit of significant improvements to current gastrointestinal cancer chemotherapy regimens, systems that allow multiple concomitant therapeutic options (polytherapy) and controlled release are highly desirable. In this sense, MOF-based nanotherapeutics represent a significant step towards achieving this goal. Here, the current state-of-the-art of interdisciplinary research and novel developments into MOF-based gastrointestinal cancer therapy are highlighted and reviewed.

Improved oral bioavailability, cellular uptake, and cytotoxic activity of zingerone via nano-micelles drug delivery system

Herein, a nano-micelle drug delivery system was developed to orally improved zingerone's bioavailability and its antitumor effect. Indeed, zingerone-loaded d-α-tocopheryl polyethylene glycol succinate micelles (ZTMs) were effectively prepared, characterised and assessed. The ZTMs had diameter, polydispersity index, and zeta potential of 50.62 ± 0.25 nm, 0.168 ± 0.006, and -28.07 ± 0.33 mV, respectively, coupled with a high entrapment efficiency (m/m, %) were 94.71 ± 2.02. The release rate of ZTMs in three media was significantly greater than that of free zingerone. Intriguingly, results obtained from pharmacokinetic studies showed that the oral bioavailability of the ZTMs was enhanced by 5.10 times in comparison with the free zingerone. Further, the half inhibitory concentration (IC50) of ZTMs and free zingerone was 7.56 μg/ml and 14.30 μg/ml, respectively, on HepG2 cells. Hence, ZTMs may be used as a potential approach to enrich the solubility, bioavailability, and concomitant anti-proliferative effect of zingerone in vitro.

Albumin Nanoparticle Formulation for Heart-Targeted Drug Delivery: In Vivo Assessment of Congestive Heart Failure

Congestive heart failure is a fatal cardiovascular disease resulting in tissue necrosis and loss of cardiac contractile function. Inotropic drugs such as milrinone are commonly used to improve the myocardial contractility and heart function. However, milrinone is associated with severe side effects and lower circulation time. In this article, a novel protein nanoparticle formulation for heart-targeted delivery of milrinone has been designed and tested. The formulation was prepared using albumin protein conjugated with the targeting ligand, angiotensin II peptide to form nanoparticles following the ethanol desolvation method. The formulation was characterized for size, charge, and morphology and tested in a rat model of congestive heart failure to study pharmacokinetics, biodistribution, and efficacy. The overall cardiac output parameters were evaluated comparing the formulation with the control non-targeted drug, milrinone lactate. This formulation exhibited improved pharmacokinetics with a mean retention time of 123.7 min, half-life of 101.3 min, and clearance rate of 0.24 L/(kg*h). The targeted formulation also significantly improved ejection fraction and fractional shortening parameters thus improving cardiac function. This study demonstrates a new approach in delivering inotropic drugs such as milrinone for superior treatment of congestive heart failure.

Augmenting the Immune Response against a Stabilized HIV-1 Clade C Envelope Trimer by Silica Nanoparticle Delivery

The delivery of HIV-1 envelope (Env) trimer-based immunogens on the surface of nanoparticles holds promise to promote immunogenicity with the aim of inducing a potent, durable and broad neutralizing antibody (bnAb) response. Towards that goal, we examined the covalent conjugation of Env to 100 nm and 200 nm silica nanoparticles (SiNPs) to optimize conjugation density and attachment stability. Env was redesigned to enable site-specific cysteine-mediated covalent conjugation while maintaining its structural integrity and antigenicity. Env was anchored to different sized SiNPs with a calculated spacing of 15 nm between adjacent trimers. Both particle sizes exhibited high in vitro stability over a seven-day period. After attachment, 100 nm particles showed better colloidal stability compared to 200 nm particles. Importantly, the antigenic profile of Env was not impaired by surface attachment, indicating that the quaternary structure was maintained. In vitro Env uptake by dendritic cells was significantly enhanced when Env was delivered on the surface of nanoparticles compared to soluble Env. Furthermore, multivalent Env displayed efficiently activated B cells even at Env concentrations in the low nanomolar range. In mice, antibody responses to nanoparticle-coupled Env were stronger compared to the free protein and had equivalent effects at lower doses and without adjuvant.

Methylene blue associated with maghemite nanoparticles has antitumor activity in breast and ovarian carcinoma cell lines

Background

Cancer constitutes group of diseases responsible for the second largest cause of global death, and it is currently considered one of the main public health concerns nowadays. Early diagnosis associated with the best choice of therapeutic strategy, is essential to achieve success in cancer treatment. In women, breast cancer is the second most common type, whereas ovarian cancer has the highest lethality when compared to other neoplasms of the female genital system. The present work, therefore, proposes the association of methylene blue with citrate-coated maghemite nanoparticles (MAGCIT–MB) as a nanocomplex for the treatment of breast and ovarian cancer.

Results

In vitro studies showed that T-47D and A2780 cancer cell lines underwent a significant reduction in cell viability after treatment with MAGCIT–MB, an event not observed in non-tumor (HNTMC and HUVEC) cells and MDA-MB-231, a triple-negative breast cancer cell line. Flow cytometry experiments suggest that the main mechanism of endocytosis involved in the interiorization of MAGCIT–MB is the clathrin pathway, whereas both late apoptosis and necrosis are the main types of cell death caused by the nanocomplex. Scanning electron microscopy and light microscopy reveal significant changes in the cell morphology. Quantification of reactive oxygen species confirmed the MAGCIT–MB cytotoxic mechanism and its importance for the treatment of tumor cells. The lower cytotoxicity of individual solution of maghemite nanoparticles with citrate (MAGCIT) and free methylene blue (MB) shows that their association in the nanocomplex is responsible for its enhanced therapeutic potential in the treatment of breast and ovarian cancer in vitro.

Conclusions

Treatment with MAGCIT–MB induces the death of cancer cells but not normal cells. These results highlight the importance of the maghemite core for drug delivery and for increasing methylene blue activity, aiming at the treatment of breast and ovarian cancer.

Graphic Abstract

Neuroprotective Efficacy of Co-Encapsulated Rosiglitazone and Vorinostat Nanoparticle on Streptozotocin Induced Mice Model of Alzheimer Disease

Anomalies in brain insulin signaling have been demonstrated to be involved in the pathology of Alzheimer disease (AD). In this context, the neuroprotective efficacy of an insulin sensitizer, rosiglitazone, has been confirmed in our previous study. In the present study, we hypothesize that a combination of an epigenetic modulator, vorinostat, along with rosiglitazone can impart improved gene expression of neurotrophic factors and attenuate biochemical and cellular alteration associated with AD mainly by loading these drugs in a surface modified nanocarrier system for enhanced bioavailability and enhanced therapeutic efficacy. Hence, in this study, rosiglitazone and vorinostat were loaded onto a poloxamer stabilized polymeric nanocarrier system and administered to mice in the intracerebroventricular streptozotocin (3 mg/kg) induced model of AD. Treatment with the free drug combination (rosiglitazone 5 mg/kg, vorinostat 25 mg/kg) for 3 weeks attenuated the behavioral, biochemical, and cellular alterations as compared to either treatment alone (rosiglitazone 10 mg/kg, vorinostat 50 mg/kg). Further, the coencapsulated nanoformulation (rosiglitazone 5 mg/kg, vorinostat 25 mg/kg) exerted better neuroprotective efficacy than the free drug combination as evidenced by improved behavioral outcome, reduced oxidative stress, and elevated levels of neurotrophic factors. In conclusion, the synergistic neuroprotective efficacy of rosiglitazone and vorinostat has been increased through the poloxamer stabilized polymeric nanocarrier system.

Understanding nano-engineered particle-cell interactions: biological insights from mathematical models

Understanding the interactions between nano-engineered particles and cells is necessary for the rational design of particles for therapeutic, diagnostic and imaging purposes. In particular, the informed design of particles relies on the quantification of the relationship between the physicochemical properties of the particles and the rate at which cells interact with, and subsequently internalise, particles. Quantitative models, both mathematical and computational, provide a powerful tool for elucidating this relationship, as well as for understanding the mechanisms governing the intertwined processes of interaction and internalisation. Here we review the different types of mathematical and computational models that have been used to examine particle-cell interactions and particle internalisation. We detail the mathematical methodology for each type of model, the benefits and limitations associated with the different types of models, and highlight the advances in understanding gleaned from the application of these models to experimental observations of particle internalisation. We discuss the recent proposal and ongoing community adoption of standardised experimental reporting, and how this adoption is an important step toward unlocking the full potential of modelling approaches. Finally, we consider future directions in quantitative models of particle-cell interactions and highlight the need for hybrid experimental and theoretical investigations to address hitherto unanswered questions.

Kinetics of nanoparticle uptake into and distribution in human cells

Whether one wishes to optimise drug delivery using nano-sized carriers or avoid hazard posed by engineered nanomaterials, the kinetics of nanoparticle uptake into human cells and their subsequent intracellular distribution is key. Unique properties of the nanoscale implies that such nanoparticles are taken up and trafficked in a different fashion compared to molecular species. In this review, we discuss in detail how to describe the kinetics of nanoparticle uptake and intracellular distribution, using previous studies for illustration. We also cover the extracellular kinetics, particle degradation, endosomal escape and cell division, ending with an outlook on the future of kinetic studies.

Exploration and insights into the cellular internalization and intracellular fate of amphiphilic polymeric nanocarriers

The beneficial or deleterious effects of nanomedicines emerge from their complex interactions with intracellular pathways and their subcellular fate. Moreover, the dynamic nature of plasma membrane accounts for the movement of these nanocarriers within the cell towards different organelles thereby not only influencing their pharmacokinetic and pharmacodynamic properties but also bioavailability, therapeutic efficacy and toxicity. Therefore, an in-depth understanding of underlying parameters controlling nanocarrier endocytosis and intracellular fate is essential. In order to direct nanoparticles towards specific sub-cellular organelles the physicochemical attributes of nanocarriers can be manipulated. These include particle size, shape and surface charge/chemistry. Restricting the particle size of nanocarriers below 200 nm contributes to internalization via clathrin and caveolae mediated pathways. Similarly, a moderate negative surface potential confers endolysosomal escape and targeting towards mitochondria, endoplasmic reticulum (ER) and Golgi. This review aims to provide an insight into these physicochemical attributes of nanocarriers fabricated using amphiphilic graft copolymers affecting cellular internalization. Fundamental principles understood from experimental studies have been extrapolated to draw a general conclusion for the designing of optimized nanoparticulate drug delivery systems and enhanced intracellular uptake via specific endocytic pathway.

Differences in surface chemistry of iron oxide nanoparticles result in different routes of internalization

The efficient entry of nanotechnology-based pharmaceuticals into target cells is highly desired to reach high therapeutic efficiency while minimizing the side effects. Despite intensive research, the impact of the surface coating on the mechanism of nanoparticle uptake is not sufficiently understood yet. Herein, we present a mechanistic study of cellular internalization pathways of two magnetic iron oxide nanoparticles (MNPs) differing in surface chemistry into A549 cells. The MNP uptake was investigated in the presence of different inhibitors of endocytosis and monitored by spectroscopic and imaging techniques. The results revealed that the route of MNP entry into cells strongly depends on the surface chemistry of the MNPs. While serum bovine albumin-coated MNPs entered the cells via clathrin-mediated endocytosis (CME), caveolin-mediated endocytosis (CavME) or lipid rafts were preferentially involved in the internalization of polyethylene glycol-coated MNPs. Our data indicate that surface engineering can contribute to an enhanced delivery efficiency of nanoparticles.

Strategies for Delivering Nanoparticles across Tumor Blood Vessels

Nanoparticle transport across tumor blood vessels is a key step in nanoparticle delivery to solid tumors. However, the specific pathways and mechanisms of this nanoparticle delivery process are not fully understood. Here, the biological and physical characteristics of the tumor vasculature and the tumor microenvironment are explored and how these features affect nanoparticle transport across tumor blood vessels is discussed. The biological and physical methods to deliver nanoparticles into tumors are reviewed and paracellular and transcellular nanoparticle transport pathways are explored. Understanding the underlying pathways and mechanisms of nanoparticle tumor delivery will inform the engineering of safer and more effective nanomedicines for clinical translation.

Lipo-PEG nano-ocular formulation successfully encapsulates hydrophilic fluconazole and traverses corneal and non-corneal path to reach posterior eye segment

The present study describes a special lipid-polyethylene glycol matrix solid lipid nanoparticles (SLNs; 138 nm; -2.07 mV) for ocular delivery. Success of this matrix to encapsulate (entrapment efficiency - 62.09%) a hydrophilic drug, fluconazole (FCZ-SLNs), with no burst release (67% release in 24 h) usually observed with most water-soluble drugs, is described presently. The system showed 164.64% higher flux than the marketed drops (Zocon^®) through porcine cornea. Encapsulation within SLNs and slow release did not compromise efficacy of FCZ-SLNs. Latter showed in vitro and in vivo antifungal effects, including antibiofilm effects comparable to free FCZ solution. Developed system was safe and stable (even to sterilisation by autoclaving); and showed optimal viscosity, refractive index and osmotic pressure. These SLNs could reach up to retina following application as drops. The mechanism of transport via corneal and non-corneal transcellular pathways is described by fluorescent and TEM images of mice eye cross sections. Particles streamed through the vitreous, crossed inner limiting membrane and reached the outer retinal layers.

Safety assessment of polymeric micelles as an ophthalmic drug delivery system for intravitreal administration of dasatinib

BACKGROUND AND AIMS

Ocular safety/biocompatibility is an essential element of ophthalmic drug delivery. We previously applied poly(ethylene glycol)-block-poly(ɛ-caprolactone) (PEG-b-PCL) micelles to deliver dasatinib for the management of proliferative vitreoretinopathy (PVR) in vitro. Herein, we seek to ascertain the ocular safety/compatibility of blank and dasatinib loaded PEG-b-PCL micelles, which will set the stage for the future in vivo efficacy evaluations and/or clinical translation for PVR or other eye diseases.

METHODS

To access the safety of blank and dasatinib loaded micelles, in vitro cell based assays (LDH cell membrane damage test, SRB cytotoxicity, TEER and permeability of RPE tight junctions), in vivo slit lamp biomicroscopy and optical coherence tomography, Ex vivo histology (H&E staining, GFAP immunofluorescence staining and TUNEL assay) were undertaken.

RESULTS

Both blank and dasatinib loaded micelles showed remarkable safety profiles at cellular levels. They also caused negligible ocular toxicity/abnormalities up to 28 days post-intravitreal injection in mice. The micelles did not insult the cornea, as demonstrated by slit-lamp biomicroscopy. Ex vivo histology and in vivo optical coherence tomography revealed a normal retinal structure with minimal apoptosis and stresses.

CONCLUSION

Taken together, both blank and dasatinib loaded micelles appear to be safe and their applications in drug delivery for eye diseases should be explored.

Targeted Nanoparticles Harboring Jasmine-Oil-Entrapped Paclitaxel for Elimination of Lung Cancer Cells

Selectively targeted drug delivery systems are preferable chemotherapeutic platforms, as they specifically deliver the drug cargo into tumor cells, while minimizing untoward toxic effects. However, these delivery systems suffer from insufficient encapsulation efficiency (EE), encapsulation capacity (EC), and premature drug release. Herein, we coencapsulated paclitaxel (PTX) and Jasmine oil (JO) within PEG-PCL nanoparticles (NPs), with an average diameter < 50 nm, selectively targeted to non-small cell lung cancer (NSCLC) cells, via S15-aptamer (APT) decoration. JO was selected as an "adhesive" oily core to enhance PTX entrapment, as JO and PTX share similar hydrophobicity and terpenoid structure. JO markedly enhanced EE of PTX from 23% to 87.8% and EC from 35 ± 6 to 74 ± 8 µg PTX/mg PEG-PCL. JO also markedly increased the residual amount of PTX after 69 h, from 18.3% to 65%. Moreover, PTX cytotoxicity against human NSCLC A549 cells was significantly enhanced due to the co-encapsulation with JO; the IC50 value for PTX encapsulated within JO-containing APT-NPs was 20-fold lower than that for APT-NPs lacking JO. Remarkably, JO-containing APT-NPs displayed a 6-fold more potent cell-killing, relatively to the free-drug. Collectively, these findings reveal a marked synergistic contribution of JO to the cytotoxic activity of APT-NP-based systems, for targeted PTX delivery against NSCLC, which may be readily applied to various hydrophobic chemotherapeutics.

Engineered Nanomaterials: The Challenges and Opportunities for Nanomedicines

The emergence of nanotechnology as a key enabling technology over the past years has opened avenues for new and innovative applications in nanomedicine. From the business aspect, the nanomedicine market was estimated to worth USD 293.1 billion by 2022 with a perception of market growth to USD 350.8 billion in 2025. Despite these opportunities, the underlying challenges for the future of engineered nanomaterials (ENMs) in nanomedicine research became a significant obstacle in bringing ENMs into clinical stages. These challenges include the capability to design bias-free methods in evaluating ENMs' toxicity due to the lack of suitable detection and inconsistent characterization techniques. Therefore, in this literature review, the state-of-the-art of engineered nanomaterials in nanomedicine, their toxicology issues, the working framework in developing a toxicology benchmark and technical characterization techniques in determining the toxicity of ENMs from the reported literature are explored.

Ruthenium tris(2,2'-bipyridyl) complex encapsulated in nanosized faujasite zeolite as intracellular localization tracer

Designing zeolites for medical applications is a challenging task that requires introducing new functionalities without altering the intrinsic properties such as morphology, crystallinity, colloidal stability, surface charge, and porosity. Herein, we present the encapsulation of luminescent ruthenium-tris(2,2'-bipyridyl) complex in faujasite (FAU) zeolite nanocrystals (Ru(bpy)₃-FAU) and their use as an intracellular localization tracer. Upon exciting the Ru(bpy)₃-FAU zeolite at 450 nm, the sample gives rise to an orange-red emission at 628 nm, thus permitting its use for cellular imaging and localization of the zeolite nanoparticles. The nanosized Ru(bpy)₃-FAU zeolite is characterized in terms of size, charge, crystallinity, morphology, porosity, thermal stability, and sorption capacity. The potential toxicity of Ru(bpy)₃-FAU on U251-MG glioblastoma cells was evaluated. A safe concentration (50-100 µg/ml) for the Ru(bpy)₃-FAU zeolite is identified. The luminescent properties of the ruthenium complex confined in the zeolite nanocrystals allow their localization in the U251-MG cells with a main accumulation in the cytoplasm. The Ru(bpy)₃-FAU nanosized zeolite is a potential candidate for biological applications for being stable, safe, capable of loading respiratory gases, and easily probed in the cells owing to its luminescent properties.

Effects of nanoparticle-mediated growth factor gene transfer to the injured microenvironment on the tendon-to-bone healing strength

The tendon-to-bone healing after trauma is usually slow and weak, and the repair site is easily disrupted during early mobilization exercise. bFGF and VEGFA gene therapy may hold promise in augmenting the tendon-to-bone healing process through enhancing cell proliferation and angiogenesis. This study is conducted to determine the effects of nanoparticle-mediated co-delivery of bFGF and VEGFA genes to the tendon-to-bone repair interface on the healing strength and biological responses in a chicken model. The PLGA nanoparticle/pEGFP-bFGF + pEGFP-VEGFA plasmid complexes were prepared and were characterized in vitro and in vivo. The nanoparticle/plasmid complexes can effectively transfer bFGF and VEGFA genes to the tendon-to-bone interface. Nanoparticle-mediated co-delivery of bFGF and VEGFA genes significantly improved the tendon-to-bone healing in terms of healing strengths and histology in a chicken flexor tendon repair model. Our results suggest a new biological approach to accelerate the tendon-to-bone healing.

Folate and Pegylated Aliphatic Polyester Nanoparticles for Targeted Anticancer Drug Delivery

Purpose

The use of chemotherapeutic agents to combat cancer is accompanied by high toxicity due to their inability to discriminate between cancer and normal cells. Therefore, cancer therapy research has focused on the targeted delivery of drugs to cancer cells. Here, we report an in vitro study of folate-poly(ethylene glycol)-poly(propylene succinate) nanoparticles (FA-PPSu-PEG-NPs) as a vehicle for targeted delivery of the anticancer drug paclitaxel in breast and cervical cancer cell lines.

Methods

Paclitaxel-loaded-FA-PPSu-PEG-NPs characterization was performed by in vitro drug release studies and cytotoxicity assays. The NPs cellular uptake and internalization mechanism were monitored by live-cell imaging in different cancer cell lines. Expression of folate receptor-α (FOLR1) was examined in these cell lines, and specific FOLR1-mediated entry of the FA-PPSu-PEG-NPs was investigated by free folic acid competition. Using inhibitors for other endocytic pathways, alternative, non-FOLR1 dependent routes for NPs uptake were also examined.

Results

Drug release experiments of Paclitaxel-loaded PPSu-PEG-NPs indicated a prolonged release of Paclitaxel over several days. Cytotoxicity of Paclitaxel-loaded PPSu-PEG-NPs was similar to free drug, as monitored in cancer cell lines. Live imaging of cells treated with either free Paclitaxel or Paclitaxel-loaded PPSu-PEG-NPs demonstrated tubulin-specific cell cycle arrest, with similar kinetics. Folate-conjugated NPs (FA-PPSu-PEG-NPs) targeted the FOLR1 receptor, as shown by free folic acid competition of the FA-PPSu-PEG-NPs cellular uptake in some of the cell lines tested. However, due to the differential expression of FOLR1 in the cancer cell lines, as well as the intrinsic differences between the different endocytic pathways utilized by different cell types, other mechanisms of nanoparticle cellular entry were also used, revealing that dynamin-dependent endocytosis and macropinocytosis pathways mediate, at least partially, cellular entry of the FA-PPSu-PEG NPs.

Conclusion

Our data provide evidence that Paclitaxel-loaded-FA-PPSu-PEG-NPs can be used for targeted delivery of the drug, FA-PPSu-PEG-NPs can be used as vehicles for other anticancer drugs and their cellular uptake is mediated through a combination of FOLR1 receptor-specific endocytosis, and macropinocytosis. The exploration of the different cellular uptake mechanisms could improve treatment efficacy or allow a decrease in dosage of anticancer drugs.

Application of advances in endocytosis and membrane trafficking to drug delivery

Multidisciplinary research efforts in the field of drug delivery have led to the development of a variety of drug delivery systems (DDS) designed for site-specific delivery of diagnostic and therapeutic agents. Since efficient uptake of drug carriers into target cells is central to effective drug delivery, a comprehensive understanding of the biological pathways for cellular internalization of DDS can facilitate the development of DDS capable of precise tissue targeting and enhanced therapeutic outcomes. Diverse methods have been applied to study the internalization mechanisms responsible for endocytotic uptake of extracellular materials, which are also the principal pathways exploited by many DDS. Chemical inhibitors remain the most commonly used method to explore endocytotic internalization mechanisms, although genetic methods are increasingly accessible and may constitute more specific approaches. This review highlights the molecular basis of internalization pathways most relevant to internalization of DDS, and the principal methods used to study each route. This review also showcases examples of DDS that are internalized by each route, and reviews the general effects of biophysical properties of DDS on the internalization efficiency. Finally, options for intracellular trafficking and targeting of internalized DDS are briefly reviewed, representing an additional opportunity for multi-level targeting to achieve further specificity and therapeutic efficacy.

Inhaled nanoparticles-An updated review

We are providing an update to our previously published review paper on inhaled nanoparticles, thus updating with the most recent reports in the literature. The field of nanotechnology may hold the promise of significant improvements in the health and well-being of patients, as well as in manufacturing technologies. The knowledge of the impact of nanomaterials on public health is limited so far. This paper reviews the unique size-controlled properties of nanomaterials, their disposition in the body after inhalation, and the factors influencing the fate of inhaled nanomaterials. The physiology of the lungs makes it an ideal target organ for non-invasive local and systemic drug delivery, especially for protein and poorly water-soluble drugs that have low oral bioavailability via oral administration. More recently, inhaled nanoparticles have been reported to improve therapeutic efficacies and decrease undesirable side effects via pulmonary delivery. The potential application of pulmonary drug delivery of nanoparticles to the lungs, specifically in context of published results reported on nanomaterials in environmental epidemiology and toxicology is reviewed in this paper. This article presents updated delivery systems, process technologies, and potential of inhaled nanoparticles for local and systemic therapies administered to the lungs. The authors acknowledge the contributions of Wei Yang in our 2008 paper published in this journal.

Nanotechnology-based Drug Delivery, Metabolism and Toxicity

BACKGROUND

Nanoparticles (NPs) are being used extensively owing to their increased surface area, targeted delivery and enhanced retention. NPs have the potential to be used in many disease conditions. Despite widespread use, their toxicity and clinical safety still remain a major concern.

OBJECTIVE

The purpose of this study was to explore the metabolism and toxicological effects of nanotherapeutics.

METHODS

Comprehensive, time-bound literature search was done covering the period from 2010 till date. The primary focus was on the metabolism of NP including their adsorption, degradation, clearance, and bio-persistence. This review also focuses on updated investigations on NPs with respect to their toxic effects on various in vitro and in vivo experimental models.

RESULTS

Nanotechnology is a thriving field of biomedical research and an efficient drug delivery system. Further their applications are under investigation for diagnosis of disease and as medical devices.

CONCLUSION

The toxicity of NPs is a major concern in the application of NPs as therapeutics. Studies addressing metabolism, side-effects and safety of NPs are desirable to gain maximum benefits of nanotherapeutics.

Current Approaches and Techniques in Physiologically Based Pharmacokinetic (PBPK) Modelling of Nanomaterials

There have been efforts to develop physiologically based pharmacokinetic (PBPK) models for nanomaterials (NMs). Since NMs have quite different kinetic behaviors, the applicability of the approaches and techniques that are utilized in current PBPK models for NMs is warranted. Most PBPK models simulate a size-independent endocytosis from tissues or blood. In the lungs, dosimetry and the air-liquid interface (ALI) models have sometimes been used to estimate NM deposition and translocation into the circulatory system. In the gastrointestinal (GI) tract, kinetics data are needed for mechanistic understanding of NM behavior as well as their absorption through GI mucus and their subsequent hepatobiliary excretion into feces. Following absorption, permeability (P_t) and partition coefficients (PCs) are needed to simulate partitioning from the circulatory system into various organs. Furthermore, mechanistic modelling of organ- and species-specific NM corona formation is in its infancy. More recently, some PBPK models have included the mononuclear phagocyte system (MPS). Most notably, dissolution, a key elimination process for NMs, is only empirically added in some PBPK models. Nevertheless, despite the many challenges still present, there have been great advances in the development and application of PBPK models for hazard assessment and risk assessment of NMs.