Deficit in the epidermal barrier induces toxicity and translocation of PEG modified graphene oxide in nematodes

The mechanical, optical, and thermal properties of graphene influencing its pre-clinical use in treating neurological diseases

Rapid progress in nanotechnology has advanced fundamental neuroscience and innovative treatment using combined diagnostic and therapeutic applications. The atomic scale tunability of nanomaterials, which can interact with biological systems, has attracted interest in emerging multidisciplinary fields. Graphene, a two-dimensional nanocarbon, has gained increasing attention in neuroscience due to its unique honeycomb structure and functional properties. Hydrophobic planar sheets of graphene can be effectively loaded with aromatic molecules to produce a defect-free and stable dispersion. The optical and thermal properties of graphene make it suitable for biosensing and bioimaging applications. In addition, graphene and its derivatives functionalized with tailored bioactive molecules can cross the blood-brain barrier for drug delivery, substantially improving their biological property. Therefore, graphene-based materials have promising potential for possible application in neuroscience. Herein, we aimed to summarize the important properties of graphene materials required for their application in neuroscience, the interaction between graphene-based materials and various cells in the central and peripheral nervous systems, and their potential clinical applications in recording electrodes, drug delivery, treatment, and as nerve scaffolds for neurological diseases. Finally, we offer insights into the prospects and limitations to aid graphene development in neuroscience research and nanotherapeutics that can be used clinically.

The Caenorhabditis elegans cuticle plays an important role against toxicity to bisphenol A and bisphenol S

Caenorhabditis elegans represents a favorite non-mammalian animal model, which is often used to study the effect of foreign substances on living organisms. Its epidermal barrier is a primary biological barrier that protects nematodes from the toxicity of chemicals. In this study, we investigated the effect of Bisphenol A (BPA), an endocrine disrupting chemical, and its structural analog Bisphenol S (BPS), which is often used as a substitute for BPA in some products, on the behavior of C. elegans wild type (N2) and C. elegans bli-1 mutant strain, which is characterized by the production of abnormal cuticle blisters. We found that exposure of C. elegans wild type (N2), as well as its mutant strain bli-1, to selected concentrations of BPA (0.1, 0.5, 1 and 5 µM) and BPS (0.1, 0.5, 1 and 5 µM) resulted in significant changes in reproduction, habituation behavior, and body length of nematodes. Based on our findings, we can conclude that BPS, which was supposed to be a safer alternative to BPA, caused almost identical detrimental effects on C. elegans behavior. Furthermore, compared to the wild type of C. elegans, these effects were more pronounced in the bli-1 strain, which is characterized by a mutation in an individual collagen gene responsible for proper cuticle formation, underlying the role of the epidermal barrier in bisphenol toxicity. Taken together, our data indicate the potential risks of using BPS as a BPA alternative.

Graphene oxide/alginate/silk fibroin composite as a novel bionanostructure with improved blood compatibility, less toxicity and enhanced mechanical properties

For biomedical applications, the design and synthesis of biocompatible nanostructures, are considered as critical challenges. In this study, graphene oxide (GO) was covalently modified by natural sodium alginate (Alg) polymer. By adding silk fibroin (SF) to this nanostructure, a hybrid nanobiocomposite (GO/Alg/SF) was resulted and its unique features were determined using FT-IR, EDX, FE-SEM, XRD and TG analyses. Because of using less toxic and high biocompatible materials, specific biological results were achieved. The cell viability of this novel nanostructure was 89.2 % and its hemolytic effect was less than 6% while the highest concentration (1000 μg/mL) of this nanostructure was chosen for these purposes. Also, high mechanical properties including the compressive strength (0.87 ± 0.034 (MPa)) and the compressive modulus (2.25 ± 0.091 (MPa)) were exposed. This nanostructure can be considered as a scaffold for wound dressing applications due to the mentioned properties.

Dysregulation of let-7 by PEG modified graphene oxide in nematodes with deficit in epidermal barrier

In nematode Caenorhabditis elegans, epidermal RNA interference (RNAi) knockdown of bli-1 encoding a cuticular collagen caused the toxicity induction of GO-PEG (PEG surface modified graphene oxide). In this study, we further found that epidermal RNAi knockdown of bli-1 increased expression of a microRNA let-7, and let-7 mutation suppressed the susceptibility of bli-1(RNAi) nematodes to GO-PEG toxicity. let-7 regulated the toxicity induction of GO-PEG by suppressing expression and function of its direct targets (HBL-1 and LIN-41). Like the nematodes with epidermal RNAi knockdown of bli-1, epidermal RNAi knockdown of hbl-1 or lin-41 also induced functional abnormality in epidermal barrier. Therefore, a signaling cascade of BLI-1-let-7-HBL-1/LIN-41 was raised to be involved in GO-PEG toxicity induction. Our data imply the dysregulation of let-7-mediated molecular machinery for developmental timing control by GO-PEG in nematodes with deficit in epidermal barrier caused by bli-1(RNAi).

Graphene-Based Nanocomposites for Neural Tissue Engineering

Graphene has made significant contributions to neural tissue engineering due to its electrical conductivity, biocompatibility, mechanical strength, and high surface area. However, it demonstrates a lack of biological and chemical cues. Also, it may cause potential damage to the host body, limiting its achievement of efficient construction of neural tissues. Recently, there has been an increasing number of studies showing that combining graphene with other materials to form nano-composites can provide exceptional platforms for both stimulating neural stem cell adhesion, proliferation, differentiation and neural regeneration. This suggests that graphene nanocomposites are greatly beneficial in neural regenerative medicine. In this mini review, we will discuss the application of graphene nanocomposites in neural tissue engineering and their limitations, through their effect on neural stem cell differentiation and constructs for neural regeneration.