Deciphering the Effects of 2D Black Phosphorus on Disrupted Hematopoiesis and Pulmonary Immune Homeostasis Using a Developed Flow Cytometry Method.

As an emerging two-dimensional nanomaterial with promising prospects, mono- or few-layer black phosphorus (BP) is potentially toxic to humans. We investigated the effects of two types of BPs on adult male mice through intratracheal instillation. Using the flow cytometry method, the generation, migration, and recruitment of immune cells in different organs have been characterized on days 1, 7, 14, and 21 post-exposure. Compared with small BP (S-BP, lateral size at ∼188 nm), large BP (L-BP, lateral size at ∼326 nm) induced a stronger stress lymphopoiesis and B cell infiltration into the alveolar sac. More importantly, L-BP dramatically increased peripheral neutrophil (NE) counts up to 1.9-fold on day 21 post-exposure. Decreased expression of the CXCR4 on NEs, an important regulator of NE retention in the bone marrow, explained the increased NE release into the circulation induced by L-BP. Therefore, BP triggers systemic inflammation via the disruption of both the generation and migration of inflammatory immune cells.

Identification of mercury-containing nanoparticles in the liver and muscle of cetaceans.

Natural mercury-containing nanoparticles (Hg-NPs) have been found in the environment, but the information for Hg-NPs in organisms was still limited. Clarifying the unique roles of Hg-NPs in organisms is crucial to fully understand the health risks of Hg. Herein, liver and muscle tissues of cetaceans were collected to identify the presence and characteristics of Hg-NPs. We found that methylmercury (MeHg) was the dominant species of Hg in muscles, while inorganic Hg (IHg) accounted for 84.4-99.0% (average 94.0%) of Hg in livers. By using transmission electron microscopy (TEM), size exclusion chromatography coupled with inductively coupled plasma mass spectrometry (SEC-ICPMS) and single particle ICPMS (sp-ICPMS), large amounts (9-161 µg/g) of Hg-NPs in livers and small amounts (0.1-0.4 µg/g) in muscles were observed, indicating that Hg-NPs was an important form of Hg in livers. Both small sized (5-40 nm) and large sized (>100 nm) Hg-NPs were identified, which were mainly complexed with selenium (Se) and sulfur (S) as well as a few cadmium (Cd), lead (Pb) and silver (Ag). This study provided direct evidence of Hg-NPs in marine mammals as well as their chemical form and size distribution, which are helpful for further understanding the biogeochemical cycle and health risk of Hg.

Developmental Toxicity of Few-Layered Black Phosphorus toward Zebrafish.

Black phosphorus (BP) has extensive applications in various fields. The release of BP into aquatic ecosystems and the potential toxic effects on aquatic organisms are becoming major concerns. Here, we investigated the developmental toxicity of few-layered BP toward the zebrafish. We found that BP could adsorb on the surface of the chorion and could subsequently penetrate within the embryo. After exposure of embryos to 10 mg/L BP, developmental malformations appeared at 96 hpf, especially heart deformities such as pericardial edema and bradycardia, accompanied by severe circulatory system failure. Using transgenic zebrafish larvae, we further characterized cardiovascular defects with cardiac enlargement and impaired cardiac vessels as indicators of damage to the cardiovascular system upon BP exposure. We performed transcriptomic analysis on zebrafish embryos treated with a lower concentration of 2 mg/L. The results showed disruption in genes associated with muscle development, oxygen involved processes, focal adhesion, and VEGF and MAPK signaling pathways. These alterations also indicated that BP carries a risk of developmental perturbation at lower concentrations. This study provides new insights into the effects of BP on aquatic organisms.

Property-Activity Relationship of Black Phosphorus at the Nano-Bio Interface: From Molecules to Organisms.

As a novel member of the two-dimensional nanomaterial family, mono- or few-layer black phosphorus (BP) with direct bandgap and high charge carrier mobility is promising in many applications such as microelectronic devices, photoelectronic devices, energy technologies, and catalysis agents. Due to its benign elemental composition (phosphorus), large surface area, electronic/photonic performances, and chemical/biological activities, BP has also demonstrated a great potential in biomedical applications including biosensing, photothermal/photodynamic therapies, controlled drug releases, and antibacterial uses. The nature of the BP-bio interface is comprised of dynamic contacts between nanomaterials (NMs) and biological systems, where BP and the biological system interact. The physicochemical interactions at the nano-bio interface play a critical role in the biological effects of NMs. In this review, we discuss the interface in the context of BP as a nanomaterial and its unique physicochemical properties that may affect its biological effects. Herein, we comprehensively reviewed the recent studies on the interactions between BP and biomolecules, cells, and animals and summarized various cellular responses, inflammatory/immunological effects, as well as other biological outcomes of BP depending on its own physical properties, exposure routes, and biodistribution. In addition, we also discussed the environmental behaviors and potential risks on environmental organisms of BP. Based on accumulating knowledge on the BP-bio interfaces, this review also summarizes various safer-by-design strategies to change the physicochemical properties including chemical stability and nano-bio interactions, which are critical in tuning the biological behaviors of BP. The better understanding of the biological activity of BP at BP-bio interfaces and corresponding methods to overcome the challenges would promote its future exploration in terms of bringing this new nanomaterial to practical applications.

Cellular Uptake of Few-Layered Black Phosphorus and the Toxicity to an Aquatic Unicellular Organism.

With the potential continuous application of mono- or few-layered black phosphorus (BP) in electronic, photonic, therapeutic, and environmental fields, the possible side effects of BP on aquatic organisms after release into natural water are of great concern. We investigated the potential toxicity of BP on the unicellular organism, Tetrahymena thermophila. After the exposure for 8 h at 10 µg/mL, the reproduction of T. thermophila significantly decreased by 46.3%. Severe cell membrane and cilium damage were observed by scanning electron microscopy (SEM) upon treatment with BP. Based on bright-field microscopy and three-dimensional Raman imaging, we investigated the cellular uptake and translocation of BP within T. thermophila. It was observed that the engulfment of BP by T. thermophila was oral apparatus dependent, through which intracellular BP was then transported to the posterior end of T. thermophila by food vacuole packaging. Our study also revealed that BP induced the increase of intracellular reactive oxidant species and formed oxidative stress-dependent toxicity to T. thermophila. Our findings paved a way for better understanding the BP toxicityon aquatic organisms and its potential ecological risks.

Mutual detoxification of mercury and selenium in unicellular Tetrahymena.

Selenium (Se) is commonly recognized as a protective element with an antagonistic effect against mercury (Hg) toxicity. However, the mechanisms of this Hg-Se antagonism are complex and remain controversial. To gain insight into the Hg-Se antagonism, a type of unicellular eukaryotic protozoa (Tetrahymena malaccensis, T. malaccensis) was selected and individually or jointly exposed to two Hg and three Se species. We found that Se species showed different toxic effects on the proliferation of T. malaccensis with the toxicity following the order: selenite (Se(IV))>selenomethionine (SeMeth)>selenate (Se(VI)). The Hg-Se antagonism in Tetrahymena was observed because the joint toxicity significantly decreased under co-exposure to highly toxic dosages of Hg and Se versus individual toxicity. Unlike Se(IV) and Se(VI), non-toxic dosage of SeMeth significantly decreased the Hg toxicity, revealing the influence of the Se species and dosages on the Hg-Se antagonism. Unexpectedly, inorganic divalent Hg (Hg2+) and monomethylmercury (MeHg) also displayed detoxification towards extremely highly toxic dosages of Se, although their detoxifying efficiency was discrepant. These results suggested mutual Hg-Se detoxification in T. malaccensis, which was highly dependent on the dosages and species of both elements. As compared to other species, SeMeth and MeHg promoted the Hg-Se joint effects to a higher degree. Additionally, the Hg contents decreased for all the Hg-Se co-exposed groups, revealing a sequestering effect of Se towards Hg in T. malaccensis.

Stable black phosphorus/Bi2O3 heterostructures for synergistic cancer radiotherapy.

X-ray induced photodynamic therapy (X-ray-PDT) is a promising approach for synergistic cancer radiotherapy and development of suitable radiosensitizers is highly desired. In this paper, we propose black phosphorus/Bi2O3 (BP/Bi2O3) heterostructures as efficient and biocompatible radiosensitizers for synergistic cancer radiotherapy. The heterostructures are synthesized by growth of ultrasmall Bi2O3 nanoparticles onto BP nanosheets. The Bi2O3 decoration inhibits the rapid degradation of BP nanosheets by occupation of the defect sites, and the synergistic effects of BP and Bi2O3 enable 1O2 overproduction under X-ray irradiation. This X-ray-PDT effect of the BP/Bi2O3 nanosheets enhances the radiotherapy activity towards cancer cells by inducing cell apoptosis and cycle arrest. In vivo treatment of melanoma conducted on a clinical radiotherapeutic instrument demonstrates that the BP/Bi2O3 sensitized radiotherapy inhibits tumor growth efficiently. Furthermore, the BP/Bi2O3 nanosheets composed of biological friendly P, O, and Bi elements shows good biocompatibility in vitro and in vivo. This radiosensitizer thus has immense clinical potential for cancer therapy, and our findings reveal a general strategy to fabricate stable BP-based heterostructures for different applications.

The association between vitamin D level and diabetic peripheral neuropathy in patients with type 2 diabetes mellitus: An update systematic review and meta-analysis.

AIM: Recently, increasing studies have been carried out to explore the association between vitamin D level and the development of diabetic peripheral neuropathy (DPN) in patients with diabetes mellitus (DM). However, because of the shortcoming in study design and sample size, there is still no clear conclusion. We performed this meta-analysis to examine the exact impact of vitamin D deficiency on DPN in type 2 diabetic patients. METHODS: Various databases were searched to identify the potential articles which explored the association between vitamin D level and diabetic peripheral neuropathy in type 2 diabetes. We pooled OR to assess the correlation between vitamin D deficiency and DPN using the random-effects model. The standardized mean difference (SMD) with 95% CI of vitamin D was also calculated to evaluate the vitamin D level between DPN and non DPN in T2DM. RESULTS: There was obvious heterogeneity in those included ten studies (I2 = 94.1%, Cochran Q test P < 0.001) using mean and standard deviation (SD) of vitamin D level. In Caucasian, vitamin D level was significantly lower in DPN patients compared with diabetic patients without DPN (SMD = -0.56, I2 = 16.9%). In Asian, the pooled OR value of vitamin D deficiency was 1.22 (95%CI: 1.17-1.27). Sensitivity analysis showed one study had great influence on this meta-analysis and it still existed after excluded that one. There was no evidence of public bias in meta analysis as showed in Begg test and Egger test. CONCLUSION: This meta-analysis indicates that vitamin D deficiency is associated with the generation and development of DPN in Caucasian with T2DM, and in Asian, diabetic patients with vitamin D deficiency are 1.22 times to suffer from DPN compared with normal vitamin D level. Vitamin D supplementation is urgently needed to prevent the development of DPN in T2DM.

Improved Biocompatibility of Black Phosphorus Nanosheets by Chemical Modification.

Black phosphorus nanosheets (BPs) show great potential for various applications including biomedicine, thus their potential side effects and corresponding improvement strategy deserve investigation. Here, in vitro and in vivo biological effects of BPs with and without titanium sulfonate ligand (TiL4 ) modification are investigated. Compared to bare BPs, BPs with TiL4 modification (TiL4 @BPs) can efficiently escape from macrophages uptake, and reduce cytotoxicity and proinflammation. The corresponding mechanisms are also discussed. These findings may not only guide the applications of BPs, but also propose an efficient strategy to further improve the biocompatibility of BPs.