Smart Nanomaterials in Cancer Theranostics: Challenges and Opportunities

Cancer is ranked as the second leading cause of death globally. Traditional cancer therapies including chemotherapy are flawed, with off-target and on-target toxicities on the normal cells, requiring newer strategies to improve cell selective targeting. The application of nanomaterial has been extensively studied and explored as chemical biology tools in cancer theranostics. It shows greater applications toward stability, biocompatibility, and increased cell permeability, resulting in precise targeting, and mitigating the shortcomings of traditional cancer therapies. The nanoplatform offers an exciting opportunity to gain targeting strategies and multifunctionality. The advent of nanotechnology, in particular the development of smart nanomaterials, has transformed cancer diagnosis and treatment. The large surface area of nanoparticles is enough to encapsulate many molecules and the ability to functionalize with various biosubstrates such as DNA, RNA, aptamers, and antibodies, which helps in theranostic action. Comparatively, biologically derived nanomaterials perceive advantages over the nanomaterials produced by conventional methods in terms of economy, ease of production, and reduced toxicity. The present review summarizes various techniques in cancer theranostics and emphasizes the applications of smart nanomaterials (such as organic nanoparticles (NPs), inorganic NPs, and carbon-based NPs). We also critically discussed the advantages and challenges impeding their translation in cancer treatment and diagnostic applications. This review concludes that the use of smart nanomaterials could significantly improve cancer theranostics and will facilitate new dimensions for tumor detection and therapy.

Easy and Versatile Synthesis of Bulk Quantities of Highly Enriched 13C-Graphene Materials for Biological and Safety Applications

The preparation of bulk quantities of ¹³C-labeled graphene materials is relevant for basic investigations and for practical applications. In addition, ¹³C-labeled graphene materials can be very useful in biological and environmental studies, as they may allow the detection of graphene or its derivatives in cells or organs. In this paper, we describe the synthesis of ¹³C-labeled graphene materials (few-layer graphene, FLG, and graphene oxide, GO) on a tens of mg scale, starting from ¹³C-labeled methane to afford carbon fibers, followed by liquid-phase exfoliation (FLG) or oxidation (GO). The materials have been characterized by several analytical and microscopic techniques, including Raman and nuclear magnetic resonance spectroscopies, thermogravimetric analysis, X-ray photoelectron spectroscopy, and X-ray powder diffraction. As a proof of concept, the distribution of the title compounds in cells has been investigated. In fact, the analysis of the ¹³C/¹²C ratio with isotope ratio mass spectrometry (IRMS) allows the detection and quantification of very small amounts of material in cells or biological compartments with high selectivity, even when the material has been degraded. During the treatment of ¹³C-labeled FLG with HepG2 cells, 4.1% of the applied dose was found in the mitochondrial fraction, while 4.9% ended up in the nuclear fraction. The rest of the dose did not enter into the cell and remained in the plasma membrane or in the culture media.

The Effects of Temperature and Humidity on the Microstructure of Sulfonated Syndiotactic-polystyrene Ionic Membranes

Polymeric membranes based on the semi-crystalline syndiotactic-polystyrene (sPS) become hydrophilic, and therefore conductive, following the functionalization of the amorphous phase by the solid-state sulfonation procedure. Because the crystallinity of the material, and thus the mechanical strength of the membranes, is maintained and the resistance to oxidation decomposition can be improved by doping the membranes with fullerenes, the sPS becomes attractive for proton-exchange membranes fuel cells (PEMFC) and energy storage applications. In the current work we report the micro-structural characterization by small-angle neutron scattering (SANS) method of sulfonated sPS films and sPS-fullerene composite membranes at different temperatures between 20 °C and 80 °C, under the relative humidity (RH) level from 10% to 70%. Complementary characterization of membranes was carried out by FTIR, UV-Vis spectroscopy and prompt-γ neutron activation analysis in terms of composition, following the specific preparation and functionalization procedure, and by XRD with respect to crystallinity. The hydrated ionic clusters are formed in the hydrated membrane and shrink slightly with the increasing temperature, which leads to a slight desorption of water at high temperatures. However, it seems that the conductive properties of the membranes do not deteriorate with the increasing temperature and that all membranes equilibrated in liquid water show an increased conductivity at 80 °C compared to the room temperature. The presence of fullerenes in the composite membrane induces a tremendous increase in the conductivity at high temperatures compared to fullerenes-free membranes. Apparently, the observed effects may be related to the formation of additional hydrated pathways in the composite membrane in conjunction with changes in the dynamics of water and polymer.

The Multilevel Structure of Sulfonated Syndiotactic-Polystyrene Model Polyelectrolyte Membranes Resolved by Extended Q-Range Contrast Variation SANS

Membranes based on sulfonated synditoactic polystyrene (s-sPS) were thoroughly characterized by contrast variation small-angle neutron scattering (SANS) over a wide Q-range in dry and hydrated states. Following special sulfonation and treatment procedures, s-sPS is an attractive material for fuel cells and energy storage applications. The film samples were prepared by solid-state sulfonation, resulting in uniform sulfonation of only the amorphous phase while preserving the crystallinity of the membrane. Fullerenes, which improve the resistance to oxidation decomposition, were incorporated in the membranes. The fullerenes seem to be chiefly located in the amorphous regions of the samples, and do not influence the formation and evolution of the morphologies in the polymer films, as no significant differences were observed in the SANS patterns compared to the fullerenes-free s-sPS membranes, which were investigated in a previous study. The use of uniaxially deformed film samples, and neutron contrast variation allowed for the identification and characterization of different structural levels with sizes between nm and μm, which form and evolve in both the dry and hydrated states. The scattering length density of the crystalline regions was varied using the guest exchange procedure between different toluene isotopologues incorporated into the sPS lattice, while the variation of the scattering properties of the hydrated amorphous regions was achieved using different H2O/D2O mixtures. Due to the deformation of the films, the scattering characteristics of different structures can be distinguished on specific detection sectors and at different detection distances after the sample, depending on their size and orientation.

Uptake and Transfer of 13C-Fullerenols from Scenedesmus obliquus to Daphnia magna in an Aquatic Environment

Fullerenol, a water-soluble polyhydroxylated fullerene nanomaterial, enters aquatic organisms and ecosystems through different ingestion exposures and may pose environmental risks. The study of their uptake routes and transfer in aquatic systems is scarce. Herein, we quantitatively investigated the aquatic uptake and transfer of ¹³C-fullerenols from Scenedesmus obliquus to Daphnia magna using ¹³C-skeleton-labeling techniques. The bioaccumulation and depuration of fullerenol in Daphnia magna increased with exposure doses and time, reaching steady state within 16 h in aqueous and feeding-affected aqueous routes. The capacity of Daphnia magna to ingest fullerenol via the aqueous route was much higher than that via the dietary route. From the aqueous to feeding-affected aqueous, the kinetic analysis demonstrated the bioaccumulation factors decreases, which revealed that algae suppressed Daphnia magna uptake of fullerenols. The aqueous route was the primary fullerenols ingestion pathway for Daphnia magna. Kinetic analysis of the accumulation and transfer in Daphnia magna via the dietary route indicated low transfer efficiency of fullerenol along the Scenedesmus obliquus-Daphnia magna food chain. Using stable isotope labeling techniques, these quantitative data revealed that carbon nanomaterials underwent complex aquatic accumulation and transfer from primary producers to secondary consumers and algae inhibited their transfer in food chains.

Bioaccumulation and Toxicity of 13C-Skeleton Labeled Graphene Oxide in Wheat

Graphene nanomaterials have many diverse applications, but are considered to be emerging environmental pollutants. Thus, their potential environmental risks and biosafety are receiving increased attention. Bioaccumulation and toxicity evaluations in plants are essential for biosafety assessment. In this study, ¹³C-stable isotope labeling of the carbon skeleton of graphene oxide (GO) was applied to investigate the bioaccumulation and toxicity of GO in wheat. Bioaccumulation of GO was accurately quantified according to the ¹³C/¹²C ratio. Wheat seedlings were exposed to ¹³C-labeled GO at 1.0 mg/mL in nutrient solution for 15 d. ¹³C-GO accumulated predominantly in the root with a content of 112 μg/g at day 15, hindered the development and growth of wheat plants, disrupted root structure and cellular ultrastructure, and promoted oxidative stress. The GO that accumulated in the root showed extremely limited translocation to the stem and leaves. During the experimental period, GO was excreted slowly from the root. GO inhibited the germination of wheat seeds at high concentrations (≥0.4 mg/mL). The mechanism of GO toxicity to wheat may be associated with oxidative stress induced by GO bioaccumulation, reflected by the changes of malondialdehyde concentration, catalase activity, and peroxidase activity. The results demonstrate that ¹³C labeling is a promising method to investigate environmental impacts and fates of carbon nanomaterials in biological systems.

Recent advances in carbon based nanosystems for cancer theranostics

This review deals with four different types of carbon allotrope based nanosystems and summarizes the results of recent studies that are likely to have applications in cancer theranostics. We discuss the applications of these nanosystems for cancer imaging, drug delivery, hyperthermia, and PDT/TA/PA.

Surface modification-mediated biodistribution of ¹³C-fullerene C₆₀ in vivo

BACKGROUND

Functionalization is believed to have a considerable impact on the biodistribution of fullerene in vivo. However, a direct comparison of differently functionalized fullerenes is required to prove the hypothesis. The purpose of this study was to investigate the influences of surface modification on the biodistribution of fullerene following its exposure via several routs of administration.

METHODS

(13)C skeleton-labeled fullerene C60 ((13)C-C60) was functionalized with carboxyl groups ((13)C-C60-COOH) or hydroxyl groups ((13)C-C60-OH). Male ICR mice (~25 g) were exposed to a single dose of 400 μg of (13)C-C60-COOH or (13)C-C60-OH in 200 μL of aqueous 0.9% NaCl solution by three different exposure pathways, including tail vein injection, gavage and intraperitoneal exposure. Tissue samples, including blood, heart, liver, spleen, stomach, kidneys, lungs, brain, large intestine, small intestine, muscle, bone and skin were subsequently collected, dissected, homogenized, lyophilized, and analyzed by isotope ratio mass spectrometry.

RESULTS

The liver, bone, muscle and skin were found to be the major target organs for C60-COOH and C60-OH after their intravenous injection, whereas unmodified C60 was mainly found in the liver, spleen and lung. The total uptakes in liver and spleen followed the order: C60 > > C60-COOH > C60-OH. The distribution rate over 24 h followed the order: C60 > C60-OH > C60-COOH. C60-COOH and C60-OH were both cleared from the body at 7 d post exposure. C60-COOH was absorbed in the gastrointestinal tract following gavage exposure and distributed into the heart, liver, spleen, stomach, lungs, intestine and bone tissues. The translocation of C60-OH was more widespread than that of C60-COOH after intraperitoneal injection.

CONCLUSIONS

The surface modification of fullerene C60 led to a decreased in its accumulation level and distribution rate, as well as altering its target organs. These results therefore demonstrate that the chemical functionalization of fullerene had a significant impact on its translocation and biodistribution properties. Further surface modifications could therefore be used to reduce the toxicity of C60 and improve its biocompatibility, which would be beneficial for biomedical applications.