Time-dependent degradation of carbon nanotubes correlates with decreased reactive oxygen species generation in macrophages

Cytometry in the Short-Wave Infrared

Cytometry plays a crucial role in characterizing cell properties, but its restricted optical window (400-850 nm) limits the number of stained fluorophores that can be detected simultaneously and hampers the study and utilization of short-wave infrared (SWIR; 900-1700 nm) fluorophores in cells. Here we introduce two SWIR-based methods to address these limitations: SWIR flow cytometry and SWIR image cytometry. We develop a quantification protocol for deducing cellular fluorophore mass. Both systems achieve a limit of detection of ∼0.1 fg cell-1 within a 30 min experimental time frame, using individualized, high-purity (6,5) single-wall carbon nanotubes as a model fluorophore and macrophage-like RAW264.7 as a model cell line. This high-sensitivity feature reveals that low-dose (6,5) serves as an antioxidant, and cell morphology and oxidative stress dose-dependently correlate with (6,5) uptake. Our SWIR cytometry holds immediate applicability for existing SWIR fluorophores and offers a solution to the issue of spectral overlapping in conventional cytometry.

Seamless Integration of Conducting Hydrogels in Daily Life: From Preparation to Wearable Application

Conductive hydrogels (CHs) have received significant attention for use in wearable devices because they retain their softness and flexibility while maintaining high conductivity. CHs are well suited for applications in skin-contact electronics and biomedical devices owing to their high biocompatibility and conformality. Although highly conductive hydrogels for smart wearable devices are extensively researched, a detailed summary of the outstanding results of CHs is required for a comprehensive understanding. In this review, the recent progress in the preparation and fabrication of CHs is summarized for smart wearable devices. Improvements in the mechanical, electrical, and functional properties of high-performance wearable devices are also discussed. Furthermore, recent examples of innovative and highly functional devices based on CHs that can be seamlessly integrated into daily lives are reviewed.

PPM1G regulates hepatic ischemia/reperfusion injury through STING-mediated inflammatory pathways in macrophages

BACKGROUND

Ischemia/reperfusion injury (IRI) is generally unavoidable following liver transplantation. Here, we investigated the role of protein phosphatase, Mg2+ /Mn2+ dependent 1G (PPM1G) in hepatic IRI.

METHODS

Hepatic IRI was mimicked by employing a hypoxia/reperfusion (H/R) model in RAW 264.7 cells and a 70% warm ischemia model in C57BL/6 mice, respectively. In vitro, expression changes of tumor necrosis factor-α and interleukin were detected by quantitative real-time polymerase chain reaction (qRT-PCR), western blot analysis, and enzyme-linked immunosorbent assay. The protein expressions of PPM1G and the stimulator of interferon genes (STING) pathway components were analyzed by western blot. Interaction between PPM1G and STING was verified by coimmunoprecipitation (CO-IP). Immunofluorescence was applied for detection of p-IRF3. Flow cytometry, qRT-PCR and western blot were utilized to analyze markers of macrophage polarization. In vivo, histological analyses of mice liver were carried out by TUNEL and H&E staining. Changes in serum aminotransferases were also detected.

RESULTS

Following H/R intervention, a steady decline in PPM1G along with an increase in inflammatory cytokines in vitro was observed. Addition of plasmid with PPM1G sequence limited the release of inflammatory cytokines and downregulated phosphorylation of STING. CO-IP validated the interaction between PPM1G and STING. Furthermore, inhibition of PPM1G with lentivirus enhanced phosphorylation of STING and its downstream components; meanwhile, p65, p38, and Jnk were also surged to phosphorylation. Expression of INOS and CD86 was surged, while CD206, Arg-1, and IL-10 were inhibited. In vivo, PPM1G inhibition further promoted liver damage, hepatocyte apoptosis, and transaminases release. Selective inhibition of STING with C-176 partially reversed the activation of STING pathway and inflammatory cytokines in vitro. M1 markers were also suppressed by C-176. In vivo, C-176 rescued liver damage and transaminase release caused by PPM1G inhibition.

CONCLUSION

PPM1G suppresses hepatic IRI and macrophage M1 phenotype by repressing STING-mediated inflammatory pathways.

Carbon nanotube nanocomposite scaffolds: advances in fabrication and applications for tissue regeneration and cancer therapy

Carbon nanotube (CNT) nanocomposite scaffolds have emerged as highly promising frameworks for tissue engineering research. By leveraging their intrinsic electrical conductivity and valuable mechanical properties, CNTs are commonly dispersed into polymers to create robust, electrically conductive scaffolds that facilitate tissue regeneration and remodeling. This article explores the latest progress and challenges related to CNT dispersion, functionalization, and scaffold printing techniques, including electrospinning and 3D printing. Notably, these CNT scaffolds have demonstrated remarkable positive effects across various cell culture systems, stimulating neuronal growth, promoting cardiomyocyte maturation, and facilitating osteocyte differentiation. These encouraging results have sparked significant interest within the regenerative medicine field, including neural, cardiac, muscle, and bone regenerations. However, addressing the concern of CNT cytotoxicity in these scaffolds remains critical. Consequently, substantial efforts are focused on exploring strategies to minimize cytotoxicity associated with CNT-based scaffolds. Moreover, researchers have also explored the intriguing possibility of utilizing the natural cytotoxic properties of CNTs to selectively target cancer cells, opening up promising avenues for cancer therapy. More research should be conducted on cutting-edge applications of CNT-based scaffolds through phototherapy and electrothermal ablation. Unlike drug delivery systems, these novel methodologies can combine 3D additive manufacturing with the innate physical properties of CNT in response to electromagnetic stimuli to efficiently target localized tumors. Taken together, the unique properties of CNT-based nanocomposite scaffolds position them as promising candidates for revolutionary breakthroughs in both regenerative medicine and cancer treatment. Continued research and innovation in this area hold significant promise for improving healthcare outcomes.

Long-term continuous degradation of carbon nanotubes by a bacteria-driven Fenton reaction

Very few bacteria are known that can degrade carbon nanotubes (CNTs), and the only known degradation mechanism is a Fenton reaction driven by Labrys sp. WJW with siderophores, which only occurs under iron-deficient conditions. No useful information is available on the degradation rates or long-term stability and continuity of the degradation reaction although several months or more are needed for CNT degradation. In this study, we investigated long-term continuous degradation of oxidized (carboxylated) single-walled CNTs (O-SWCNTs) using bacteria of the genus Shewanella. These bacteria are widely present in the environment and can drive the Fenton reaction by alternating anaerobic-aerobic growth conditions under more general environmental conditions. We first examined the effect of O-SWCNTs on the growth of S. oneidensis MR-1, and it was revealed that O-SWCNTs promote growth up to 30 μg/mL but inhibit growth at 40 μg/mL and above. Then, S. oneidensis MR-1 was subjected to incubation cycles consisting of 21-h anaerobic and 3-h aerobic periods in the presence of 30 μg/mL O-SWCNTs and 10 mM Fe(III) citrate. We determined key factors that help prolong the bacteria-driven Fenton reaction and finally achieved long-term continuous degradation of O-SWCNTs over 90 d. By maintaining a near neutral pH and replenishing Fe(III) citrate at 60 d, a degraded fraction of 56.3% was reached. S. oneidensis MR-1 produces Fe(II) from Fe(III) citrate, a final electron acceptor for anaerobic respiration during the anaerobic period. Then, ·OH is generated through the Fenton reaction by Fe(II) and H2O2 produced by MR-1 during the aerobic period. ·OH was responsible for O-SWCNT degradation, which was inhibited by scavengers of H2O2 and ·OH. Raman spectroscopy and X-ray photoelectron spectroscopy showed that the graphitic structure in O-SWCNTs was oxidized, and electron microscopy showed that long CNT fibers initially aggregated and became short and isolated during degradation. Since Shewanella spp. and iron are ubiquitous in the environment, this study suggests that a Fenton reaction driven by this genus is applicable to the degradation of CNTs under a wide range of conditions and will help researchers develop novel methods for waste treatment and environmental bioremediation against CNTs.

Application of Conductive Hydrogels on Spinal Cord Injury Repair: A Review

Spinal cord injury (SCI) causes severe motor or sensory damage that leads to long-term disabilities due to disruption of electrical conduction in neuronal pathways. Despite current clinical therapies being used to limit the propagation of cell or tissue damage, the need for neuroregenerative therapies remains. Conductive hydrogels have been considered a promising neuroregenerative therapy due to their ability to provide a pro-regenerative microenvironment and flexible structure, which conforms to a complex SCI lesion. Furthermore, their conductivity can be utilized for noninvasive electrical signaling in dictating neuronal cell behavior. However, the ability of hydrogels to guide directional axon growth to reach the distal end for complete nerve reconnection remains a critical challenge. In this Review, we highlight recent advances in conductive hydrogels, including the incorporation of conductive materials, fabrication techniques, and cross-linking interactions. We also discuss important characteristics for designing conductive hydrogels for directional growth and regenerative therapy. We propose insights into electrical conductivity properties in a hydrogel that could be implemented as guidance for directional cell growth for SCI applications. Specifically, we highlight the practical implications of recent findings in the field, including the potential for conductive hydrogels to be used in clinical applications. We conclude that conductive hydrogels are a promising neuroregenerative therapy for SCI and that further research is needed to optimize their design and application.

Follow the time course of inflammation caused by intraperitoneal administration of multi-wall carbon nanotubes in mice

OBJECTIVE

Understand the progress of inflammation over time caused by multi-walled carbon nanotubes (MWCNT).

METHODS

Two types of MWCNTs were administered to C57BL/6N mice via intraperitoneal administration at low and high doses (0.05 and 1.0 mg/mouse, respectively). Inflammation was evaluated until 6 months after administration based on cytokine levels and pathological observations. The abdominal cavity lavage fluid was collected and analyzed 1 week, 1, 3, and 6 month(s) after administration. IL-6 expression markedly increased 3 months after the administration of high-dose MWCNT-7.

RESULTS

Notable inflammation was observed in the groups administered with one of the MWCNT, MWCNT-7. On the other hand, inflammation in another MWCNT-treated group was milder than that in the MWCNT-7-treated group. MWCNT-7 induced pronounced inflammation but did not induce tumor formation during the experimental period. Inflammation reaction is one of the most important biological responses to MWCNT.

CONCLUSION

Three months post-exposure becomes a turning point for the harmful effects of the intraperitoneally administered MWCNT-7.

Assessment of Pristine Carbon Nanotubes Toxicity in Rodent Models

Carbon nanotubes are increasingly used in nanomedicine and material chemistry research, mostly because of their small size over a large surface area. Due to their properties, they are very attractive candidates for use in medicine and as drug carriers, contrast agents, biological platforms, and so forth. Carbon nanotubes (CNTs) may affect many organs, directly or indirectly, so there is a need for toxic effects evaluation. The main mechanisms of toxicity include oxidative stress, inflammation, the ability to damage DNA and cell membrane, as well as necrosis and apoptosis. The research concerning CNTs focuses on different animal models, functionalization, ways of administration, concentrations, times of exposure, and a variety of properties, which have a significant effect on toxicity. The impact of pristine CNTs on toxicity in rodent models is being increasingly studied. However, it is immensely difficult to compare obtained results since there are no standardized tests. This review summarizes the toxicity issues of pristine CNTs in rodent models, as they are often the preferred model for human disease studies, in different organ systems, while considering the various factors that affect them. Regardless, the results showed that the majority of toxicological studies using rodent models revealed some toxic effects. Even with different properties, carbon nanotubes were able to generate inflammation, fibrosis, or biochemical changes in different organs. The problem is that there are only a small amount of long-term toxicity studies, which makes it impossible to obtain a good understanding of later effects. This article will give a greater overview of the situation on toxicity in many organs. It will allow researchers to look at the toxicity of carbon nanotubes in a broader context and help to identify studies that are missing to properly assess toxicity.

Enzymatic and Cellular Degradation of Carbon-Based Biconcave Nanodisks

The assessment of the biodegradability of nanomaterials is of pragmatic importance for understanding the interactions between nanomaterials and biological systems and for the determination of ultimate fate of these materials as well as their potential use. We recently developed carbon-based biconcave nanodisks (CBBNs) serving as a versatile nanocarrier for enhanced accumulation in tumors and combined photothermal-chemotherapy. Here, we investigate both the enzymatic and cellular degradation of CBBNs by monitoring their cellular response with electron microscopy, near-infrared absorbance spectroscopy, and cell viability and oxidative stress assessments. Our results show that CBBNs underwent significant degradation in solutions catalyzed by horseradish peroxidase (HRP) and hydrogen peroxide (H₂O₂), or in the presence of macrophage cells. The ability of CBBNs to be degraded in biological systems provides suitability for their future biomedical applications.

Understanding Nanomaterial-Liver Interactions to Facilitate the Development of Safer Nanoapplications

Nanomaterials (NMs) are widely used in commercial and medical products, such as cosmetics, vaccines, and drug carriers. Exposure to NMs via various routes such as dermal, inhalation, and ingestion has been shown to gain access to the systemic circulation, resulting in the accumulation of NMs in the liver. The unique organ structures and blood flow features facilitate the liver sequestration of NMs, which may cause adverse effects in the liver. Currently, most in vivo studies are focused on NMs accumulation at the organ level and evaluation of the gross changes in liver structure and functions, however, cell-type-specific uptake and responses, as well as the molecular mechanisms at cellular levels leading to effects at organ levels are lagging. Herein, the authors systematically review diverse interactions of NMs with the liver, specifically on major liver cell types including Kupffer cells (KCs), liver sinusoidal endothelial cells (LSECs), hepatic stellate cells (HSCs), and hepatocytes as well as the detailed molecular mechanisms involved. In addition, the knowledge gained on nano-liver interactions that can facilitate the development of safer nanoproducts and nanomedicine is also reviewed.

Coronavirus and Carbon Nanotubes: Seeking Immunological Relationships to Discover Immunotherapeutic Possibilities

Since December 2019, the world has faced an unprecedented pandemic crisis due to a new coronavirus disease, coronavirus disease-2019 (COVID-19), which has instigated intensive studies on prevention and treatment possibilities. Here, we investigate the relationships between the immune activation induced by three coronaviruses associated with recent outbreaks, with special attention to SARS-CoV-2, the causative agent of COVID-19, and the immune activation induced by carbon nanotubes (CNTs) to understand the points of convergence in immune induction and modulation. Evidence suggests that CNTs are among the most promising materials for use as immunotherapeutic agents. Therefore, this investigation explores new possibilities of effective immunotherapies for COVID-19. This study aimed to raise interest and knowledge about the use of CNTs as immunotherapeutic agents in coronavirus treatment. Thus, we summarize the most important immunological aspects of various coronavirus infections and describe key advances and challenges in using CNTs as immunotherapeutic agents against viral infections and the activation of the immune response induced by CNTs, which can shed light on the immunotherapeutic possibilities of CNTs.

Vertically Aligned Carbon Nanotubes as a Unique Material for Biomedical Applications

Vertically aligned carbon nanotubes (VACNTs), a unique classification of CNT, highly oriented and normal to the respective substrate, have been heavily researched over the last two decades. Unlike randomly oriented CNT, VACNTs have demonstrated numerous advantages making it an extremely desirable nanomaterial for many biomedical applications. These advantages include better spatial uniformity, increased surface area, greater susceptibility to functionalization, improved electrocatalytic activity, faster electron transfer, higher resolution in sensing, and more. This Review discusses VACNT and its utilization in biomedical applications particularly for sensing, biomolecule filtration systems, cell stimulation, regenerative medicine, drug delivery, and bacteria inhibition. Furthermore, comparisons are made between VACNT and its traditionally nonaligned, randomly oriented counterpart. Thus, we aim to provide a better understanding of VACNT and its potential applications within the community and encourage its utilization in the future.

In Vitro Assessment Reveals the Effects of Environmentally Persistent Free Radicals on the Toxicity of Photoaged Tire Wear Particles

Tire wear particles (TWP) have been identified as one of the major sources of microplastics (MPs), and few studies have focused on their environmental behaviors and impacts. However, a thorough characteristic and toxicity assessment associated with environmentally persistent free radicals (EPFRs) on the photoaged TWP is missing. In this study, we investigated EPFRs in the process of TWP photoaging and evaluated their toxicity using in vitro bioassays. Our results showed that a total of around 1.0 × 10¹⁷ spins/g EPFRs (g-factors ranging 2.00308-2.00318) was formed on TWP with 60 days of light irradiation, which contained more than 29% of reactive EPFRs (r-EPFRs). Using macrophages as model cells for bioassays, TWP-associated EPFRs trigged endpoints, including the decrease of cell viability (27 to 45%) and the increase of oxidative stress response (46-93%) and inflammatory factor secretion. The enhancement of TWP toxicity with photoaging was confirmed to be attributed to the generated EPFRs combined with other TWP's chemical compositions (e.g., various metals and organics). Most importantly, the toxicity of photoaged TWP was closely correlated with the generated r-EPFRs, which induced reactive oxidant species (ROS) generation. This study provides direct evidence of toxicity on the photoaged TWP particles, revealing the potential contributions of EPFRs to the adverse effect on human health and highlighting the need for an improved understanding of the impacts of EPFRs on the risk assessment of TWP released into the environment.

Synthesis of physically crosslinked PAM/CNT flakes nanocomposite hydrogel films via a destructive approach

Carbon nanotube (CNT)-based hydrogels have recently found a wide variety of applications due to the unique physical and chemical properties of CNTs. CNTs can be used as a nanofiller and/or crosslinker to produce nanocomposite hydrogels with good mechanical and structural properties. In this research, a novel method was reported for producing polyacrylamide (PAM)/oxidized-multiwalled carbon nanotube (O-MWCNT) flakes nanocomposite hydrogel films without using any organic cross-linker or surfactant. Through a mechanism dependent on the reactive oxygen species (ROS), some O-MWCNTs were broken down in situ into small flakes in the aqueous solutions containing acrylamide (AM) and sodium persulfate (NaPS) at the temperature range of 85–90 °C. Simultaneously, in situ polymerization of the AM monomers occurred using free radicals, which resulted in the formation of PAM chains. The flakes acted as crosslinkers by forming hydrogen bonds with PAM chains and formed a hydrogel network after 48 h at room temperature. The hydrogels were characterized by different techniques (FT-IR, Raman, FE-SEM, TEM, TGA, tensile test). The porous structure of the hydrogel films as well as micro-network structures with unique morphologies were observed by SEM. The O-MWCNT flakes and some undegraded O-MWCNTs in the hydrogel network were also observed by TEM. The results showed that PC₂I₂H hydrogel film, as an evolved hydrogel, has excellent swelling performance in aqueous solutions at different pH and temperatures. In addition, this hydrogel showed a tensile strength of 103 MPa in the dry state and an elongation of 703% in the swollen state.

Novel PAM/CNT flakes nanocomposite hydrogel films were synthesized by in situ degradation of the oxidized-MWCNTs into flakes using persulfate activation. The flakes crosslinked the PAM chains via hydrogen bonding to form a hydrogel network.

Conductive single-wall carbon nanotubes/extracellular matrix hybrid hydrogels promote the lineage-specific development of seeding cells for tissue repair through reconstructing an integrin-dependent niche

Background

The niche of tissue development in vivo involves the growth matrix, biophysical cues and cell-cell interactions. Although natural extracellular matrixes may provide good supporting for seeding cells in vitro, it is evitable to destroy biophysical cues during decellularization. Reconstructing the bioactivities of extracellular matrix-based scaffolds is essential for their usage in tissue repair.

Results

In the study, a hybrid hydrogel was developed by incorporating single-wall carbon nanotubes (SWCNTs) into heart-derived extracellular matrixes. Interestingly, insoluble SWCNTs were well dispersed in hybrid hydrogel solution via the interaction with extracellular matrix proteins. Importantly, an augmented integrin-dependent niche was reconstructed in the hybrid hydrogel, which could work like biophysical cues to activate integrin-related pathway of seeding cells. As supporting scaffolds in vitro, the hybrid hydrogels were observed to significantly promote seeding cell adhesion, differentiation, as well as structural and functional development towards mature cardiac tissues. As injectable carrier scaffolds in vivo, the hybrid hydrogels were then used to delivery stem cells for myocardial repair in rats. Similarly, significantly enhanced cardiac differentiation and maturation(12.5 ± 2.3% VS 32.8 ± 5%) of stem cells were detected in vivo, resulting in improved myocardial regeneration and repair.

Conclusions

The study represented a simple and powerful approach for exploring bioactive scaffold to promote stem cell-based tissue repair.

Graphic abstract

Supplementary Information

The online version contains supplementary material available at 10.1186/s12951-021-00993-3.

Advances and Perspectives in the Use of Carbon Nanotubes in Vaccine Development

Advances in nanobiotechnology have allowed the utilization of nanotechnology through nanovaccines. Nanovaccines are powerful tools for enhancing the immunogenicity of a specific antigen and exhibit advantages over other adjuvant approaches, with features such as expanded stability, prolonged release, decreased immunotoxicity, and immunogenic selectivity. We introduce recent advances in carbon nanotubes (CNTs) to induce either a carrier effect as a nanoplatform or an immunostimulatory effect. Several studies of CNT-based nanovaccines revealed that due to the ability of CNTs to carry immunogenic molecules, they can act as nonclassical vaccines, a quality not possessed by vaccines with traditional formulations. Therefore, adapting and modifying the physicochemical properties of CNTs for use in vaccines may additionally enhance their efficacy in inducing a T cell-based immune response. Accordingly, the purpose of this study is to renew and awaken interest in and knowledge of the safe use of CNTs as adjuvants and carriers in vaccines.

Dual covalent functionalization of single-walled carbon nanotubes for effective targeted cancer therapy

Chemotherapy is a mainstay strategy in the management of cancer. Regrettably, current chemotherapeutic agents are cytotoxic not only to cancer cells but also to healthy cells, resulting in dose-limiting serious side effects. Therefore, many researchers are eager to develop new drug delivery systems that may help to decrease the side effects and the target delivery of chemotherapy to cancer cells. One of the epochal drug delivery systems in this field is based on carbon nanotubes technology. The aim of this work is the dual covalent functionalization of single-walled carbon nanotubes (SWCNTs) with doxorubicin (DOX) connected with acid-labile linkage and mannose (Man) as a targeting agent. The characterization of the developed nano-drug by transmission electron microscopy showed good dispersibility of the functionalized SWCNTs with diameters (6-10) nm. Moreover, the percentage of functionalization was determined by thermogravimetric analysis showing 25% of functionalization in the case of SWNCTs-NHN-DOX (7) and 51% for SWCNTs-Man-NHN-DOX (11). The in vitro release profile of Dox from SWNCTs-NHN-DOX (7) showed 45% of the loaded drug was released over 18 h at pH 7.4 and almost complete release at pH 6.4 at 37 °C. However, the in vitro release profile of Dox from SWCNTs-Man-NHN-DOX (11) showed 75% of the loaded drug was released over 5 h at pH 6.4 at 37 °C. The cytotoxic effect of the compounds was studied on liver cancer cells (HepG2) at different concentrations and different pH conditions and was compared with DOX alone. The cytotoxicity of compounds SWCNTs-NHN-DOX (7) and SWCNTs-Man-NHN-DOX (11) was enhanced at pH 6.5, where the cell viability in both test compounds was significantly reduced by almost 50% compared to the cell viability at pH 7.4 for the same test compound Moreover, the pre-incubation of cells with different concentrations of mannose reduced the cytotoxicity of compound (11) by more than 50%, suggesting that the entry of this complex could be at least in part facilitated by mannose receptors, which imparts this complex a kind of selectivity for cancer cells that overexpress this type of receptors.

Mitigation of Carbon Nanotube Neurosensor Induced Transcriptomic and Morphological Changes in Mouse Microglia with Surface Passivation

Single-walled carbon nanotubes (SWCNT) are used in neuroscience for deep-brain imaging, neuron activity recording, measuring brain morphology, and imaging neuromodulation. However, the extent to which SWCNT-based probes impact brain tissue is not well understood. Here, we study the impact of (GT)6-SWCNT dopamine nanosensors on SIM-A9 mouse microglial cells and show SWCNT-induced morphological and transcriptomic changes in these brain immune cells. Next, we introduce a strategy to passivate (GT)6-SWCNT nanosensors with PEGylated phospholipids to improve both biocompatibility and dopamine imaging quality. We apply these passivated dopamine nanosensors to image electrically stimulated striatal dopamine release in acute mouse brain slices, and show that slices labeled with passivated nanosensors exhibit higher fluorescence response to dopamine and measure more putative dopamine release sites. Hence, this facile modification to SWCNT-based dopamine probes provides immediate improvements to both biocompatibility and dopamine imaging functionality with an approach that is readily translatable to other SWCNT-based neurotechnologies.

Clearance of single-wall carbon nanotubes from the mouse lung: a quantitative evaluation

Based on the characteristics of carbon nanotubes (CNTs) that absorb light in the near-infrared region, we have developed a method to quantify the biodistribution of CNTs in mouse tissues such as the liver, lungs and spleen. By using this method, the kinetic biodistribution of single-walled CNTs (SWNTs) after intravenous injection into mice for 60 days has been successfully investigated. The results show that the biodistribution of CNTs was diameter-dependent by comparing two different diameters of SWNTs. The SWNTs with larger diameters (1-5 nm) accumulated more in the liver or spleen but less in the lungs than those with smaller diameters (0.7-0.9 nm). The quantities of both SWNTs in the liver and lungs decreased with time and showed no significant change in the spleen, which is also confirmed by histological analysis. In particular, the results have demonstrated that both SWNTs are cleared from the lungs almost completely within 60 days, suggesting that the pulmonary toxicity of SWNTs would be low when low amounts of CNTs (<70 μg g^-1 of tissue) enter inside the lungs. In addition, no obvious inflammatory responses are found from the measurement of the cytokines TGF-β1, IL-6, INF-γ, and TNF-α in the plasma and organs after the injection of both SWNTs into mice.

The Fate of SWCNTs in Mouse Peritoneal Macrophages: Exocytosis, Biodegradation, and Sustainable Retention

The understanding of toxicological and pharmacological profiles of nanomaterials is an important step for the development and clinical application of nanomedicines. Carbon nanotubes (CNTs) have been extensively explored as a nanomedicine agent in pharmaceutical/biomedical applications, such as drug delivery, bioimaging, and tissue engineering. The biological durability of CNTs could affect the function of CNTs-based nanomedicines as well as their toxicity in cells and tissues. Therefore, it is crucial to assess the fate of nanomedicine in phagocytes. Herein, we investigated the candidate fate of acid-oxidized single-walled carbon nanotubes (SWNCTs) in non-activated primary mouse peritoneal macrophages (PMQ). The sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE) results showed that the intracellular SWCNTs continued growing from 4 to 36 h in PMQ. After replacing the exposure medium, we found the exosome induced by SWCNTs on the surface of macrophages according to scanning electron microscope (SEM) observation. The near-infrared (NIR) absorption increase of the supernatant samples after post-exposure indicates that SWCNTs exocytosis occurred in PMQ. The decreasing intracellular SWCNTs amount suggested the incomplete biodegradation in PMQ, which was confirmed by Raman spectroscopy and transmission electron microscopy (TEM). The combined data reveal that SWCNTs could be retained for more than 60 h in macrophages. Then sustainable retention of SWCNTs in primary macrophages was coexist with exocytosis and biodegradation. The findings of this work will shed light on the bioimaging, diagnosis and other biomedical applications of CNTs-based nanomedicines.

Nitroxide-Modified Protein-Incorporated Nanoflowers with Dual Enzyme-Like Activities

Purpose

Combined superoxide dismutase (SOD)/catalase mimetics have attracted much attention because of their efficacy against reactive oxygen species-associated diseases; however, their application is often limited owing to their poor stability and the absence of favorable grafting sites. To address this, we developed a new class of SOD/catalase mimetics based on hybrid nanoflowers, which exhibit superior stability and possess the desired grafting sites for drugs and endogenous molecules.

Methods

In this work, for the first time, we used polynitroxylated human serum albumin (PNA) to mediate the formation of hybrid copper-based nanoflowers. H₂O₂ depletion and O₂ evolution assays were first performed to determine the catalase-like activity of the hybrid nanoflowers. Next, the xanthine oxidase/cytochrome c method was used to assay the SOD-like activity of the nanoflowers. Further characteristics of the nanoflowers were evaluated using scanning electron microscopy (SEM), electron paramagnetic resonance (EPR), and Fourier-transform infrared spectroscopy (FTIR). Operational stability was assessed via the reusability assay.

Results

The H₂O₂ depletion and O₂ evolution assays indicated that PNA-incorporated nanoflowers have genuine catalase-like activity. Kinetic analysis revealed that the reactions of the incorporated nanoflowers with H₂O₂ not only obey Michaelis-Menton kinetics, but that the nanoflowers also possess a higher affinity for H₂O₂ than that of native catalase. The FTIR spectra corroborated the presence of PNA in the hybrid nanoflowers, while the EPR spectra confirmed the intermolecular interaction of nitroxides bound to the human serum albumin incorporated into the nanoflowers. The remarkable operational reproducibility of the hybrid nanoflowers in catalase-like and SOD-like reactions was verified across successive batches.

Conclusion

Herein, a comparison of Michaelis constants showed that the hybrid nanoflower, a catalase mimetics, outperforms the native catalase. Acting as a "better-than-nature" enzyme mimetics, the hybrid nanoflower with superior stability and desired ligand grafting sites will find widespread utilization in the medical sciences.

Cytotoxicity effects and ionic diffusion of single-wall carbon nanotubes in cell membrane

While carbon nanotubes have been put into massive practical industrial, environmental and biomedicine applications, the cytotoxicity effects or the effect to the ionic channels they bring into the living cells need to be thoroughly investigated. In this work, molecular dynamic simulations have been carried out to investigate the ionic diffusion through the single wall armchair carbon nanotube embedded right inside the cell membrane. By modeling a two-membrane system, we build a virtual cytoplasm environment including a cell chamber and an extracellular space, in which a certain amount of solute is dissolved. The system is first brought to its equilibrium by deployment of minimization and then simulated. The results suggested that carbon nanotubes (CNTs) with size less than (12, 12) shall be less cytotoxic since it does not bring any ionic diffusion through the CNT channel, so as to maintain active cytoplasm environment. Another phenomenon we observed is a notable shifting angle of the carbon nanotube which was normal to the surface of cell membrane initially. In general, the inclination angle of the carbon nanotube increases with its radius.