Understanding the particokinetics of engineered nanomaterials for safe and effective therapeutic applications

Oral administration of silver nanomaterials affects the gut microbiota and metabolic profile altering the secretion of 5-HT in mice

Due to their excellent antibacterial ability, silver nanomaterials (Ag NMs) are the most frequently used nanomaterials. Their widespread use introduces the risk of human ingestion. However, the potential toxicity of Ag NMs to the gut microbiota and their metabolic profile are yet to be fully explored. In this study, we examined the effects of Ag NMs after oral administration (0.5 mg kg^-1 and 2.5 mg kg^-1, 14 and 28 days) on gut homeostasis by integrating tissue imaging, 16s rRNA gene sequencing and metabolomics techniques. We uncovered that silver nanoparticles (Ag NPs) and silver nanowires (Ag NWs) altered the structure (inhibiting the proliferation of Gram-negative bacteria) and decreased the diversity of gut microbiota in mice after short-term (14 days) exposure, while the microbial community tended to recover after long-term exposure (28 days), indicating that the resistance and resilience of the gut microbiome may pose a defense against the interference by reactive, exogenous nanomaterials. Interestingly, even though the gut microbiota structure recovered after 28 days of exposure, the gut metabolites significantly changed, showing increased 1H-indole-3-carboxylic acid and elevated levels of 5-HT in the gut and blood. Collectively, our results provide a piece of evidence on the association between the ingestion of exogenous nanoparticles and gut homeostasis, especially the metabolic profile of the host. This work thus provides additional insights for the continued investigation of the adverse effects of silver nanomaterials on biological hosts.

MicroRNAs and Their Big Therapeutic Impacts: Delivery Strategies for Cancer Intervention

Three decades have passed from the initial discovery of a microRNA (miRNA) in Caenorhabditis elegans to our current understanding that miRNAs play essential roles in regulating fundamental physiological processes and that their dysregulation can lead to many human pathologies, including cancer. In effect, restoration of miRNA expression or downregulation of aberrantly expressed miRNAs using miRNA mimics or anti-miRNA inhibitors (anti-miRs/antimiRs), respectively, continues to show therapeutic potential for the treatment of cancer. Although the manipulation of miRNA expression presents a promising therapeutic strategy for cancer treatment, it is predominantly reliant on nucleic acid-based molecules for their application, which introduces an array of hurdles, with respect to in vivo delivery. Because naked nucleic acids are quickly degraded and/or removed from the body, they require delivery vectors that can help overcome the many barriers presented upon their administration into the bloodstream. As such, in this review, we discuss the strengths and weaknesses of the current state-of-the-art delivery systems, encompassing viral- and nonviral-based systems, with a specific focus on nonviral nanotechnology-based miRNA delivery platforms, including lipid-, polymer-, inorganic-, and extracellular vesicle-based delivery strategies. Moreover, we also shed light on peptide carriers as an emerging technology that shows great promise in being a highly efficacious delivery platform for miRNA-based cancer therapeutics.

Organoids: A new approach in toxicity testing of nanotherapeutics

Nanotechnology has revolutionized diverse fields, which include agriculture, the consumer market, medicine, and other fields. Widespread use of nanotechnology-based products has led to increased prevalence of these novel formulations in the environment, which has raised concerns regarding their deleterious effects. The application of nanotechnology-based formulations into clinical use is hampered by the lack of the availability of effective in vitro systems, which could accurately assess their in vivo toxic effects. A plethora of studies has shown the hazardous effects of nanoparticle-based formulations in two-dimensional in vitro cell cultures and animal models. These have some associated disadvantages when used for the evaluation of nano-toxicity. Organoid technology fills the space between existing two-dimensional cell line culture and in vivo models. The uniqueness of organoids over other systems for evaluating toxicity caused by nano-drug formulation includes them being a co-culture of diverse cell types, dynamic flow within them that simulates the actual flow of nanoparticles within biological systems, extensive cell-cell, cell-matrix interactions, and a tissue-like morphology. Thus, it mimics the actual tissue microenvironment and, subsequently, provides an opportunity to study drug metabolism and toxico-dynamics of nanotechnology-based novel formulations. The use of organoids in the evaluation of nano-drug toxicity is in its infancy. A limited number of studies conducted so far have shown good predictive value and efficiently significant data correlation with the clinical trials. In this review, we attempt to introduce organoids of the liver, lungs, brain, kidney intestine, and potential applications to evaluate toxicity caused by nanoparticles.

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.

Monitoring AuNP Dynamics in the Blood of a Single Mouse Using Single Particle Inductively Coupled Plasma Mass Spectrometry with an Ultralow-Volume High-Efficiency Introduction System

Gold nanoparticles (AuNPs) are increasingly being used as diagnostic and therapeutic agents owing to their excellent properties; however, there is not much data available on their dynamics in vivo on a single particle basis in a single mouse. Here, we developed a method for the direct analysis of nanoparticles in trace blood samples based on single particle inductively coupled plasma-mass spectrometry (spICP-MS). A flexible, highly configurable, and precisely controlled sample introduction system was designed by assembling an ultralow-volume autosampler (flow rate in the range of 5-5000 μL/min) and a customized cyclonic spray chamber (transfer efficiency up to 99%). Upon systematic optimization, the detection limit of the nanoparticle size (LOD_size) of AuNPs in ultrapure water was 19 nm, and the detection limit of the nanoparticle number concentration (LOD_NP) was 8 × 10⁴ particle/L. Using a retro-orbital blood sampling method and subsequent dilution, the system was successfully applied to track the dynamic changes in size and concentration for AuNPs in the blood of a single mouse, and the recovery for the blood sample was 111.74%. Furthermore, the concentration of AuNPs in mouse blood reached a peak in a short period of time and, then, gradually decreased. This study provides a promising technique for analyzing and monitoring the size and concentration of nanoparticles in ultralow-volume blood samples with low concentrations, making it a powerful tool for analyzing and understanding the fate of nanoparticles in vivo.

Non-viral, direct neuronal reprogramming from human fibroblast using a polymer-functionalized nanodot

Among various strategies to treat neurodegenerative disorders, cell replacement therapies have drawn much attention recently. Such a trend led to the increase in demand for the rare and specialized cells, followed by the outburst development of various cell reprogramming strategies. However, several limitations on these conventional methods remain to be solved, including the genetic instability of the viral vectors and the high cytotoxicity or poor performance of the non-viral carriers. Therefore, non-viral methods need to be developed to ensure safe and efficient cell reprogramming. Here, we introduce a polymer-modified nano-reagent (Polymer-functionalized Nanodot, PolyN) for the safe and efficient, non-viral direct cell reprogramming. PolyN facilitated the highly efficient contemporary overexpression of the transgene compared to the conventional reagent. With our nano-reagent, we demonstrated the SOX2-mediated cell reprogramming and successfully generated the neuron-like cell from the human fibroblast.

15 Years of Small: Research Trends in Nanosafety

In the field of nano- and microscale science and technology, Small has become one of the worldwide leading journals since its initiation 15 years ago. Among all the topics covered in Small, "nanosafety" has received growing interest over the years, which accounts for a large proportion of the total publications of Small. Herein, inspired by its coming Special Issue "Rethinking Nanosafety," a general bibliometric overview of the nanosafety studies that have been published in Small is presented. Using the data derived from the Web of Science Core Collection, the annual publication growth, most influential countries/institutions as well as the visualized collaborations between different countries and institutions based on CiteSpace software are presented. A special emphasis on the impact of the previous Special Issue from Small that is related to nanosafety research is given and the research trend from the most highly cited papers during last 15 years is analyzed. Lastly, future research directions are also proposed.

Nano-bio interactions: the implication of size-dependent biological effects of nanomaterials

Due to their many advantageous properties, nanomaterials (NMs) have been utilized in diverse consumer goods, industrial products, and for therapeutic purposes. This situation leads to a constant risk of exposure and uptake by the human body, which are highly dependent on nanomaterial size. Consequently, an improved understanding of the interactions between different sizes of nanomaterials and biological systems is needed to design safer and more clinically relevant nano systems. We discuss the sizedependent effects of nanomaterials in living organisms. Upon entry into biological systems, nanomaterials can translocate biological barriers, distribute to various tissues and elicit different toxic effects on organs, based on their size and location. The association of nanomaterial size with physiological structures within organs determines the site of accumulation of nanoparticles. In general, nanomaterials smaller than 20 nm tend to accumulate in the kidney while nanomaterials between 20 and 100 nm preferentially deposit in the liver. After accumulating in organs, nanomaterials can induce inflammation, damage structural integrity and ultimately result in organ dysfunction, which helps better understand the size-dependent dynamic processes and toxicity of nanomaterials in organisms. The enhanced permeability and retention effect of nanomaterials and the utility of this phenomenon in tumor therapy are also highlighted.

Size-Optimized Ultrasmall Porous Silica Nanoparticles Depict Vasculature-Based Differential Targeting in Triple Negative Breast Cancer

Rapid sequestration and prolonged retention of intravenously injected nanoparticles by the liver and spleen (reticuloendothelial system (RES)) presents a major barrier to effective delivery to the target site and hampers clinical translation of nanomedicine. Inspired by biological macromolecular drugs, synthesis of ultrasmall (diameter ≈12-15 nm) porous silica nanoparticles (UPSNs), capable of prolonged plasma half-life, attenuated RES sequestration, and accelerated hepatobiliary clearance, is reported. The study further investigates the effect of tumor vascularization on uptake and retention of UPSNs in two mouse models of triple negative breast cancer with distinctly different microenvironments. A semimechanistic mathematical model is developed to gain mechanistic insights into the interactions between the UPSNs and the biological entities of interest, specifically the RES. Despite similar systemic pharmacokinetic profiles, UPSNs demonstrate strikingly different tumor responses in the two models. Histopathology confirms the differences in vasculature and stromal status of the two models, and corresponding differences in the microscopic distribution of UPSNs within the tumors. The studies demonstrate the successful application of multidisciplinary and complementary approaches, based on laboratory experimentation and mathematical modeling, to concurrently design optimized nanomaterials, and investigate their complex biological interactions, in order to drive innovation and translation.

Noninvasive and real-time pharmacokinetics imaging of polymeric nanoagents in the thoracoepigastric vein networks of living mice

Noninvasive and real-time visualization of the thoracoepigastric veins (TVs) of living mice was demonstrated by using two-photon excitation (TPE) optical imaging with a Eu-luminescent polymeric nanoagent as the angiographic contrast. The spatiotemporal evolution of the polymeric nanoagent in TVs was monitored for up to 2 h by TPE time-resolved (TPE-TR) bioimaging, which is free from the interference of tissue autofluorescence. A wide field-of-view covering the thoracoabdominal region allowed the visualization of the entire TV network with an imaging depth of 1 to 2 mm and a lateral resolution of 80 μm at submillimeter. Detailed analysis of the uptake, transport, and clearance processes of the polymeric nanoagent revealed a clearance time constant of ∼30  min and an apparent clearance efficiency of 80% to 90% for the nanoagent in both axial and lateral TVs. TPE-TR imaging of the dissected internal organs proved that the liver is mainly responsible for the sequestration of the nanoagent, which is consistent with the apparent retention efficiency of liver, ∼32  %  , as determined by the real-time in vivo TV imaging. We demonstrate the potency of TPE-TR modality in the pharmacokinetics imaging of the peripheral vascular systems of animal models, which can be beneficial for related nanotheranostics study.

Focus on Fundamentals: Achieving Effective Nanoparticle Targeting

Successful molecular targeting of nanoparticle drug carriers can enhance therapeutic specificity and reduce systemic toxicity. Typically, ligands specific for cognate receptors expressed on the intended target cell type are conjugated to the nanoparticle surface. This approach, often called active targeting, seems to imply that the conjugated ligand imbues the nanoparticle with homing capacity. However, ligand-receptor interactions are mediated by short-range forces and cannot produce magnetic-like attraction over larger distances. Successful targeting actually involves two key characteristics: contact of the nanoparticle with the intended target cell and subsequent ligand-mediated retention at the site. Here we propose a conceptual framework, based on recent literature combined with basic principles of molecular interactions, to guide rational design of nanoparticle targeting strategies.

Gold nanoparticle-based miR155 antagonist macrophage delivery restores the cardiac function in ovariectomized diabetic mouse model

Diabetic cardiomyopathy is a common disease in postmenopausal women, in whom the estrogen deficiency aggravates the pathology. In this study, we have found that estrogen deficiency due to ovariectomy aggravates the inflammation in the hearts of diabetic mice, as depicted by excessive proinflammatory type 1 macrophages (M1) over anti-inflammatory type 2 macrophages (M2). Accordingly, an additional increase of reactive oxygen species, cell apoptosis, cardiac hypertrophy, and fibrosis was observed in the hearts of ovariectomized diabetic mice, in comparison with the diabetes-only group. Significantly, miR155, a potent promoter of M1 polarization, was found to be additionally enhanced in the macrophages and hearts by ovariectomy. Tail vein injection of miR155-AuNP, in which thiol-modified antago-miR155 was covalently conjugated with gold nanoparticle (AuNP), preferentially delivered the nucleic acids into the macrophages via phagocytosis. Together with the increased M2 ratio and reduced inflammation, in vivo delivery of antago-miR155 reduced cell apoptosis and restored the cardiac function. The restoration efficacy of miR155-AuNP was much better than general macrophage depletion by clodrosome. In summary, we revealed that M1/M2 imbalance contributes to the aggravated cardiomyopathy in ovariectomized diabetic mice, and therapeutically reducing miR155 in macrophages by AuNP serves as a promising strategy in improving cardiac function.

Quantitative microscopy-based measurements of circulating nanoparticle concentration using microliter blood volumes

Nanoparticles (NPs) are potential drug delivery vehicles for treatment of a broad range of diseases. Intravenous (IV) administration, the most common form of delivery, is relatively non-invasive and provides (in theory) access throughout the circulatory system. However, in practice, many IV injected NPs are quickly eliminated by specialized phagocytes in the liver and spleen. Consequently, new materials have been developed with the capacity to significantly extend the circulating half-life of IV administered NPs. Unfortunately, current procedures for measuring circulation half-lives are often expensive, time consuming, and can require large blood volumes that are not compatible with mouse models of disease. Here we describe a simple and reliable procedure for measuring circulation half-life utilizing quantitative microscopy. This method requires only 2μL of blood and minimal sample preparation, yet provides robust quantitative results.

Size matters for in vitro gene delivery: investigating the relationships among complexation protocol, transfection medium, size and sedimentation

Although branched and linear polyethylenimines (bPEIs and lPEIs) are gold standard transfectants, a systematic analysis of the effects of the preparation protocol of polyplexes and the composition of the transfection medium on their physicochemical behaviour and effectiveness in vitro have been much neglected, undermining in some way the identification of precise structure-function relationships. This work aimed to address these issues. bPEI/DNA and lPEI/DNA, prepared using two different modes of addition of reagents, gave rise to polyplexes with exactly the same chemical composition but differing in dimensions. Upon dilution in serum-free medium, the size of any kind of polyplex promptly rose over time while remained invariably stable in complete DMEM. Of note, the bigger the dimension of polyplexes (in the nano- to micrometer range), the greater their efficiency in vitro. Besides, centrifugal sedimentation of polyplexes displaying different dimensions to speed up and enhance their settling onto cells boosted transfection efficiencies. Conversely, transgene expression was significantly blunted in cells held upside-down and transfected, definitively pointing out the impact of gravitational sedimentation of polyplexes on their transfection efficiency. Overall, much more attention must be paid to the actual polyplex size that relies on the complexation conditions and the transfection medium.

Assessing the Benefits of Drug Delivery by Nanocarriers: A Partico/Pharmacokinetic Framework

OBJECTIVE

An in vivo kinetic framework is introduced to analyze and predict the quantitative advantage of using nanocarriers to deliver drugs, especially anticancer agents, compared to administering the same drugs in their free form.

METHODS

This framework recognizes three levels of kinetics. First is the particokinetics associated with deposition of nanocarriers into tissues associated with drug effect and toxicity, their residence inside those tissues, and elimination of the nanocarriers from the body. Second is the release pattern in time of free drug from the nanocarriers. Third is the pharmacokinetics of free drug, as it relates to deposition and elimination processes in the target and toxicity associated tissues, and total body clearance. A figure of merit, the drug targeting index (DTI), is used to quantitate the benefit of nanocarrier-based drug delivery by considering the effects of preferential deposition of nanoparticles into target tissues and relative avoidance of tissues associated with drug toxicity, compared to drug that is administered in its free form.

RESULTS

General methods are derived for calculating DTI when appropriate particokinetic, pharmacokinetic, and drug release rate information is available, and it is shown that relatively simple algebraic forms result when some common assumptions are made.

CONCLUSION

This approach may find use in developing and selecting nanocarrier formulations, either for populations or for individuals.

In vivo kinetic biodistribution of nano-sized outer membrane vesicles derived from bacteria

Evaluation of kinetic distribution and behaviors of nanoparticles in vivo provides crucial clues into their roles in living organisms. Extracellular vesicles are evolutionary conserved nanoparticles, known to play important biological functions in intercellular, inter-species, and inter-kingdom communication. In this study, the first kinetic analysis of the biodistribution of outer membrane vesicles (OMVs)-bacterial extracellular vesicles-with immune-modulatory functions is performed. OMVs, injected intraperitoneally, spread to the whole mouse body and accumulate in the liver, lung, spleen, and kidney within 3 h of administration. As an early systemic inflammation response, increased levels of TNF-α and IL-6 are observed in serum and bronchoalveolar lavage fluid. In addition, the number of leukocytes and platelets in the blood is decreased. OMVs and cytokine concentrations, as well as body temperature are gradually decreased 6 h after OMV injection, in concomitance with the formation of eye exudates, and of an increase in ICAM-1 levels in the lung. Following OMV elimination, most of the inflammatory signs are reverted, 12 h post-injection. However, leukocytes in bronchoalveolar lavage fluid are increased as a late reaction. Taken together, these results suggest that OMVs are effective mediators of long distance communication in vivo.

Size- and surface chemistry-dependent pharmacokinetics and tumor accumulation of engineered gold nanoparticles after intravenous administration

It is important and essential to study the pharmacokinetics and biodistribution of gold nanoparticles for safer and more efficient therapeutic purposes.

Safety of Nanoparticles in Medicine

Nanomedicine involves the use of nanoparticles for therapeutic and diagnostic purposes. During the past two decades, a growing number of nanomedicines have received regulatory approval and many more show promise for future clinical translation. In this context, it is important to evaluate the safety of nanoparticles in order to achieve biocompatibility and desired activity. However, it is unwarranted to make generalized statements regarding the safety of nanoparticles, since the field of nanomedicine comprises a multitude of different manufactured nanoparticles made from various materials. Indeed, several nanotherapeutics that are currently approved, such as Doxil and Abraxane, exhibit fewer side effects than their small molecule counterparts, while other nanoparticles (e.g. metallic and carbon-based particles) tend to display toxicity. However, the hazardous nature of certain nanomedicines could be exploited for the ablation of diseased tissue, if selective targeting can be achieved. This review discusses the mechanisms for molecular, cellular, organ, and immune system toxicity, which can be observed with a subset of nanoparticles. Strategies for improving the safety of nanoparticles by surface modification and pretreatment with immunomodulators are also discussed. Additionally, important considerations for nanoparticle safety assessment are reviewed. In regards to clinical application, stricter regulations for the approval of nanomedicines might not be required. Rather, safety evaluation assays should be adjusted to be more appropriate for engineered nanoparticles.

Applications of nanomaterials as vaccine adjuvants

Vaccine adjuvants are applied to amplify the recipient's specific immune responses against pathogen infection or malignancy. A new generation of adjuvants is being developed to meet the demands for more potent antigen-specific responses, specific types of immune responses, and a high margin of safety. Nanotechnology provides a multifunctional stage for the integration of desired adjuvant activities performed by the building blocks of tailor-designed nanoparticles. Using nanomaterials for antigen delivery can provide high bioavailability, sustained and controlled release profiles, and targeting and imaging properties resulting from manipulation of the nanomaterials' physicochemical properties. Moreover, the inherent immune-regulating activity of particular nanomaterials can further promote and shape the cellular and humoral immune responses toward desired types. The combination of both the delivery function and immunomodulatory effect of nanomaterials as adjuvants is thought to largely benefit the immune outcomes of vaccination. In this review, we will address the current achievements of nanotechnology in the development of novel adjuvants. The potential mechanisms by which nanomaterials impact the immune responses to a vaccine and how physicochemical properties, including size, surface charge and surface modification, impact their resulting immunological outcomes will be discussed. This review aims to provide concentrated information to promote new insights for the development of novel vaccine adjuvants.

Gold nanoparticles for nucleic acid delivery

Gold nanoparticles provide an attractive and applicable scaffold for delivery of nucleic acids. In this review, we focus on the use of covalent and noncovalent gold nanoparticle conjugates for applications in gene delivery and RNA-interference technologies. We also discuss challenges in nucleic acid delivery, including endosomal entrapment/escape and active delivery/presentation of nucleic acids in the cell.

A quantitative recipe for engineering protein polymer nanoparticles

Protein polymers can assemble switchable nanostructures with emerging applications as biomaterials and nanomedicines. For example, above a critical micelle temperature (CMT) some elastin-like polypeptide (ELP) diblock copolymers assemble spherical nanoparticles, which may modulate cellular internalization and in vivo biodistribution. To achieve engineering-level control over their properties, this report explores a comprehensive library of ELP monoblock and diblock polymers. For the first time, we report that a surprisingly high core molecular weight is required for stable nanoparticle formation; furthermore, nanoparticle size depends on polymer molecular weight. A mathematical model was developed to characterize four ELP monoblock libraries and to predict the phase behavior of corresponding diblock copolymers. The CMT was almost entirely dependent on the hydrophobic core ELP, while the bulk phase transition temperature (T_t,bulk ) depends predominantly on the hydrophilic block. Nanoparticle assembly was accompanied by a conversion in secondary structure of the hydrophobic block from random coil and beta-sheets to type-2 β turns. For the first time, this report enables the rational design of ELP protein polymer nanoparticles with physico-chemico properties that will be suitable for biological applications.

Epidermal growth factor receptor targeted nuclear delivery and high-resolution whole cell X-ray imaging of Fe3O4@TiO2 nanoparticles in cancer cells

Sequestration within the cytoplasm often limits the efficacy of therapeutic nanoparticles that have specific subcellular targets. To allow for both cellular and subcellular nanoparticle delivery, we have created epidermal growth factor receptor (EGFR)-targeted Fe3O4@TiO2 nanoparticles that use the native intracellular trafficking of EGFR to improve internalization and nuclear translocation in EGFR-expressing HeLa cells. While bound to EGFR, these nanoparticles do not interfere with the interaction between EGFR and karyopherin-β, a protein that is critical for the translocation of ligand-bound EGFR to the nucleus. Thus, a portion of the EGFR-targeted nanoparticles taken up by the cells also reaches cell nuclei. We were able to track nanoparticle accumulation in cells by flow cytometry and nanoparticle subcellular distribution by confocal fluorescent microscopy indirectly, using fluorescently labeled nanoparticles. More importantly, we imaged and quantified intracellular nanoparticles directly, by their elemental signatures, using X-ray fluorescence microscopy at the Bionanoprobe, the first instrument of its kind in the world. The Bionanoprobe can focus hard X-rays down to a 30 nm spot size to map the positions of chemical elements tomographically within whole frozen-hydrated cells. Finally, we show that photoactivation of targeted nanoparticles in cell nuclei, dependent on successful EGFR nuclear accumulation, induces significantly more double-stranded DNA breaks than photoactivation of nanoparticles that remain exclusively in the cytoplasm.