Interaction of single and multi wall carbon nanotubes with the biological systems: tau protein and PC12 cells as targets

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.

Tunable Thermoelectric Performance of the Nanocomposites Formed by Diketopyrrolopyrrole/Isoindigo-Based Donor-Acceptor Random Conjugated Copolymers and Carbon Nanotubes

This paper presents the development of thermoelectric properties in nanocomposites comprising donor-acceptor random conjugated copolymers and single-walled carbon nanotubes (SWCNTs). The composition of the conjugated polymers, specifically the ratio of diketopyrrolopyrrole (DPP) to isoindigo (IID), is manipulated to design a series of random conjugated copolymers (DPP0, DPP5, DPP10, DPP30, DPP50, DPP90, DPP95, and DPP100). The objective is to improve the dispersion of SWCNTs into smaller bundles, leading to enhanced thermoelectric properties of the polymer/SWCNT nanocomposite. This dispersion strategy promotes an interconnected conducting network, which plays a critical role in optimizing the thermoelectric performance. Accordingly, the effects of morphologies on the thermoelectric properties of the nanocomposites are systematically investigated. The DPP95/SWCNT nanocomposite exhibits the strongest interaction, resulting in the highest power factor (PF) of 711.1 μW m-1 K-2, derived from the high electrical conductivity of 1690 S cm-1 and Seebeck coefficient of 64.8 μV K-1. The prototype flexible thermoelectric generators assembled with a DPP95/SWCNT film achieve a maximum power output of 20.4 μW m-2 at a temperature difference of 29.3 K. These findings highlight the potential of manipulating the composition of random conjugated copolymers and incorporating SWCNTs to efficiently harvest low-grade waste heat in wearable thermoelectric devices.

Nitric Oxide Detection Using a Corona Phase Molecular Recognition Site on Chiral Single-Walled Carbon Nanotubes

Semiconducting single-walled carbon nanotubes (s-SWCNT) are structures that fluoresce in the near-infrared region. By coating SWCNT surfaces with polymeric materials such as single-chain DNA, changes in fluorescence emission occur in the presence of reagents. In this way, polymer-coated SWCNT structures allow them to be used as optical sensors for single molecule detection. Especially today, the inadequacy of the methods used in the detection of cellular molecules makes the early diagnosis of diseases such as cancer difficult at the single-molecule level. In this study, the detection of nitric oxide (NO) signals, which are a marker of cancer, was carried out at the single-molecule level. In this context, a sensor structure was formed by coating the 7,6-chiral s-SWCNT surface with ssDNA with different oligonucleotide lengths (AT). The sensor structure was characterized by using UV-vis spectroscopy and Raman spectroscopy microscopy. After formation of the sensor structure, a selectivity library was created using various molecules. As a result of the coating of the SWCNT (7,6) surface with DNA corona phase formation, Raman peaks at 195 and 276 cm-1 were observed to shift to the right. Additionally, the selectivity library results showed that the (AT)30 sequence can be used in NO detection. As a result of the studies using SWCNT (7.6)- (AT)30, the limit of detection (LOD) and limit of determination (LOQ) values of the sensor against NO were found to be 1.24 and 4.13 μM, respectively.

Blocking tau transmission by biomimetic graphene nanoparticles

Tauopathies are a class of neurodegenerative diseases resulting in cognitive dysfunction, executive dysfunction, and motor disturbance. The primary pathological feature of tauopathies is the presence of neurofibrillary tangles in the brain composed of tau protein aggregates. Moreover, tau aggregates can spread from neuron to neuron and lead to the propagation of tau pathology. Although numerous small molecules are known to inhibit tau aggregation and block tau cell-to-cell transmission, it is still challenging to use them for therapeutic applications due to poor specificity and low blood-brain barrier (BBB) penetration. Graphene nanoparticles were previously demonstrated to penetrate the BBB and are amenable to functionalization for targeted delivery. Moreover, these nanoscale biomimetic particles can self-assemble or assemble with various biomolecules including proteins. In this paper, we show that graphene quantum dots (GQDs), as graphene nanoparticles, block the seeding activity of tau fibrils by inhibiting the fibrillization of monomeric tau and triggering the disaggregation of tau filaments. This behavior is attributed to electrostatic and π-π stacking interactions of GQDs with tau. Overall, our studies indicate that GQDs with biomimetic properties can efficiently inhibit and disassemble pathological tau aggregates, and thus block tau transmission, which supports their future developments as a potential treatment for tauopathies.

In vitro comparative cytotoxic assessment of pristine and carboxylic functionalized multiwalled carbon nanotubes on LN18 cells

Multiwalled carbon nanotubes (MWCNTs) have been used in biomedical applications due to their ability to enter the cells. Carboxylic functionalization of MWCNT (MWCNT-COOH) is used to mitigate the toxicity of MWCNTs. Our study focuses on comparing the toxicity of MWCNT and MWCNT-COOH on the neuronal cells, LN18. Concentrations of 5, 10, 20, and 40 µg ml-1 were used for the study, and cytotoxicity was determined at 0, 1, 3, 6, 12, 24, and 48 h of incubation. Cell viability was assessed by Trypan Blue, MTT, and Live dead cell assays, and the oxidative stress produced was determined by reactive oxygen species (ROS) and Lipid peroxidation assays. MWCNT-COOH showed higher cell viability than MWCNT for 20 and 40 µg ml-1 at 24 and 48 h. This was also visually observed in the live dead cell imaging. However, at 48 h, the morphology of the cells appeared more stretched for all the concentrations of MWCNT and MWCNT-COOH in comparison to the control. A significant amount of ROS production can also be observed at the same concentration and time. Viability and oxidative stress results together revealed that MWCNT-COOH is less toxic when compared to MWCNT at longer incubation periods and higher concentrations. However, otherwise, the effect of both are comparable. A concentration of 5-10 µg ml-1 is ideal while using MWCNT and MWCNT-COOH as the toxicity is negligible. These findings can further be extended to various functionalizations of MWCNT for wider applications.

Recent Advances in Nanomaterials of Group XIV Elements of Periodic Table in Breast Cancer Treatment

Breast cancer is one of the most common malignancies and a leading cause of cancer-related mortality among women worldwide. The elements of group XIV in the periodic table exhibit a wide range of chemical manners. Recently, there have been remarkable developments in the field of nanobiomedical research, especially in the application of engineered nanomaterials in biomedical applications. In this review, we concentrate on the recent investigations on the antiproliferative effects of nanomaterials of the elements of group XIV in the periodic table on breast cancer cells. In this review, the data available on nanomaterials of group XIV for breast cancer treatment has been documented, providing a useful insight into tumor biology and nano-bio interactions to develop more effective nanotherapeutics for cancer patients.

Non-covalent modification of single wall carbon nanotubes (SWCNTs) by thienothiophene derivatives

Non-covalent functionalization of single wall carbon nanotubes (SWCNTs) has been conducted using several binding agents with surface π-interaction forces in recent studies. Herein, we present the first example of non-covalent functionalization of sidewalls of SWCNTs using thienothiophene (TT) derivatives without requiring any binding agents. Synthesized TT derivatives, TT-CN-TPA, TT-CN-TPA2 and TT-COOH-TPA, were attached directly to SWCNTs through non-covalent interactions to obtain new TT-based SWCNT hybrids, HYBRID 1-3. Taking advantage of the presence of sulfur atoms in the structure of TT, HYBRID 1, as a representative, was treated with Au nanoparticles for the adsorption of Au by sulfur atoms, which generated clear TEM images of the particles. The images indicated the attachment of TTs to the surface of SWCNTs. Thus, the presence of sulfur atoms in TT units made the binding of TTs to SWCNTs observable via TEM analysis through adsorption of Au nanoparticles by the sulfur atoms. Surface interactions between TTs and SWCNTs of the new hybrids were also clarified by classical molecular dynamic simulations, a quantum mechanical study, and SEM, TEM, AFM and contact angle (CA) analyses. The minimum distance between a TT and a SWCNT reached up to 3.5 Å, identified with strong peaks on a radial distribution function (RDF), while maximum interaction energies were raised to -316.89 kcal mol^-1, which were determined using density functional theory (DFT).

Highly Efficient and Salt-Rejecting Poly(vinyl alcohol) Hydrogels with Excellent Mechanical Strength for Solar Desalination

Interfacial solar steam generation (ISSG)-based solar desalination has recently emerged as a promising solution to tackle the global issue of fresh water scarcity. However, the energy-intensive process of conventional vapor generation techniques limits its practical applications. Hydrogels with three-dimensional (3D) structures have been reported to alleviate this energy demand, but their applications in sustainable solar desalination are hindered by their poor mechanical stability. Herein, we propose a 3D poly(vinyl alcohol) (PVA)-based hydrogel with excellent mechanical strength for effective solar desalination. The dual polymer network hydrogel (PVA-agar) incorporated with multi-walled carbon nanotubes (MWCNTs) achieved a noticeable evaporation rate of 3.1 kg m^-2 h^-1 under 1 sun irradiation, owing to its broadband light absorption, intrinsic water channels, and microporous structure that help reduce the latent heat of vaporization. More importantly, the application of kosmotropic ammonium sulfate ions was found to greatly improve the mechanical strength of the hydrogels using a facile Hofmeister-assisted soaking method. Finally, the PVA-agar-MWCNT hydrogel was able to desalinate seawater efficiently (2.5 kg m^-2 h^-1) with self-cleaning capability of salt crystals. The salinity level of the desalinated water was also comparable to drinking clean water. The present results would pave the way for fabricating mechanically strong, hydrophilic, and highly efficient hydrogels for effective and sustainable solar desalination.

Ultrafast growth of carbon nanotubes using microwave irradiation: characterization and its potential applications

Carbon nanotubes (CNTs) have been studied for more than twenty-five years due to their distinguishing features such as high tensile strength, high elastic module, high surface area, high thermal and electrical conductivity, making them ideal for a variety of applications. Nanotechnology and nanoscience researchers are working to develop CNTs with appropriate properties for possible future applications. New methodologies for their synthesis are clearly needed to be developed and refined. In this research, the authors look at the history and the recent developments of carbon nanotubes synthesis methods for CNTs, such as arc discharge, laser ablation, chemical vapour deposition and microwave irradiation. New immerging methods like microwave irradiation for the growth of CNTs and their composite was extensively reviewed. Low temperature and ultrafast growth of CNT through microwave irradiation technique were examined and discussed. In addition, all the techniques used for the CNTs characterization were also briefly discussed. Special attention was dedicated to the application of CNTs. This review has extensively explored future applications in the biomedical sector, industrial water purifications, CNTs composites, energy and storage devices.

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Synthesis of carbon nanotubes using different methods.

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Microwave irradiation techniques are used for the growth of CNTs.

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Current challenge and future aspects of CNTs growth.

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Detailed characterization and application of CNTs.

Impacts of ingested MWCNT-Embedded nanocomposites in Japanese medaka (Oryzias latipes)

Polymer nanocomposites combine the versatile, lightweight characteristics of polymers with the properties of nanomaterials. Polyethylene terephthalate glycol (PETG) is commonly used in polymer additive manufacturing due to its controllable transparency, high modulus, and mechanical properties. Multi-walled carbon nanotubes (MWCNTs) add tensile strength, electrical conductivity, and thermal stability. The increased use of nanocomposites has led to concern over potential human health risks. We assessed morphologic alterations to determine impacts of ingested abraded nanocomposites compared to its component materials, pristine MWCNTs (1000 mg/L) and PETG. Adult transparent Japanese medaka (Oryzias latipes) were administered materials via oral gavage in 7 doses over 16 days. In vivo observations revealed altered livers and gallbladders following exposure to pristine MWCNTs and nanocomposites. Subsequent histologic sections showed fish exposed to pristine MWCNTs had highly altered biliary structures, and exposure to nanocomposites resulted in hepatocellular alteration. Thyroid follicle proliferation was also observed in fish exposed to materials containing MWCNTs. Transmission electron microscopy of livers showed that hepatocytes of fish exposed to MWCNTs had widespread swelling of rough endoplasmic reticulum, pronounced lysosomal activity, and swelling of intrahepatic biliary passageways. Fish exposed to nanocomposites had areas of degenerated hepatocytes with interspersed cellular debris. Each analysis showed that fish exposed to pristine PETG were most similar to controls. These results suggest that MWCNTs are the source of toxicity in abraded nanocomposite materials but that nanocomposites may also have some unique effects. The similarities of many teleost and mammalian tissues are such that these findings may indicate human health risks.

Binding Capabilities of Different Genetically Engineered pVIII Proteins of the Filamentous M13/Fd Virus and Single-Walled Carbon Nanotubes

Binding functional biomolecules to non-biological materials, such as single-walled carbon nanotubes (SWNTs), is a challenging task with relevance for different applications. However, no one has yet undertaken a comparison of the binding of SWNTs to different recombinant filamentous viruses (phages) bioengineered to contain different binding peptides fused to the virus coat proteins. This is important due to the range of possible binding efficiencies and scenarios that may arise when the protein’s amino acid sequence is modified, since the peptides may alter the virus’s biological properties or they may behave differently when they are in the context of being displayed on the virus coat protein; in addition, non-engineered viruses may non-specifically adsorb to SWNTs. To test these possibilities, we used four recombinant phage templates and the wild type. In the first circumstance, we observed different binding capabilities and biological functional alterations; e.g., some peptides, in the context of viral templates, did not bind to SWNTs, although it was proven that the bare peptide did. The second circumstance was excluded, as the wild-type virus was found to hardly bind to the SWNTs. These results may be relevant to the possible use of the virus as a “SWNT shuttle” in nano-scale self-assembly, particularly since the pIII proteins are free to act as binding-directing agents. Therefore, knowledge of the differences between and efficiencies of SWNT binding templates may help in choosing better binding phages or peptides for possible future applications and industrial mass production.

Cytocompatibility of carboxylated multi-wall carbon nanotubes in stem cells from human exfoliated deciduous teeth

Carboxylated multi-wall carbon nanotube (MWCNT-COOH) presents unique properties due to nanoscale dimensions and permits a broad range of applications in different fields, such as bone tissue engineering and regenerative medicine. However, the cytocompatibility of MWCNT-COOH with human stem cells is poorly understood. Thus, studies elucidating how MWCNT-COOH affects human stem cell viability are essential to a safer application of nanotechnologies. Using stem cells from the human exfoliated deciduous teeth model, we have evaluated the effects of MWCNT-COOH on cell viability, oxidative cell stress, and DNA integrity. Results demonstrated that despite the decreased metabolism of mitochondria, MWCNT-COOH had no toxicity against stem cells. Cells maintained viability after MWCNT-COOH exposure. MWCNT-COOH did not alter the superoxide dismutase activity and did not cause genotoxic effects. The present findings are relevant to the potential application of MWCNT-COOH in the tissue engineering and regenerative medicine fields.

Characterization 0.1 wt.% Nanomaterial/Photopolymer Composites with Poor Nanomaterial Dispersion: Viscosity, Cure Depth and Dielectric Properties

Notably, 3D printing techniques such as digital light processing (DLP) have the potential for the cost-effective and flexible production of polymer-based piezoelectric composites. To improve their properties, conductive nanomaterials can be added to the photopolymer to increase their dielectric properties. In this study, the microstructure, viscosity, cure depth, and dielectric properties of ultraviolet (UV) light curable 0.1 wt.% nanomaterial/photopolymer composites are investigated. The composites with multi-walled carbon nanotubes (MWCNTs), graphene nanoplatelets (GNPs), and carbon black (CB) are pre-dispersed in different solvents (acetone, isopropyl alcohol, and ethanol) before adding photopolymer and continuing dispersion. For all prepared suspensions, a reduction in viscosity is observed, which is favorable for 3D printing. In contrast, the addition of 0.1 wt.% nanomaterials, even with poor dispersion, leads to curing depth reduction up to 90% compared to pristine photopolymer, where the nanomaterial dispersion is identified as a contributing factor. The formulation of MWCNTs dispersed in ethanol is found to be the most promising for increasing the dielectric properties. The post-curing of all composites leads to charge immobility, resulting in decreased relative permittivity.

Superior operational stability of immobilized L-asparaginase over surface-modified carbon nanotubes

L-asparaginase (ASNase, EC 3.5.1.1) is an enzyme that catalyzes the L-asparagine hydrolysis into L-aspartic acid and ammonia, being mainly applied in pharmaceutical and food industries. However, some disadvantages are associated with its free form, such as the ASNase short half-life, which may be overcome by enzyme immobilization. In this work, the immobilization of ASNase by adsorption over pristine and modified multi-walled carbon nanotubes (MWCNTs) was investigated, the latter corresponding to functionalized MWCNTs through a hydrothermal oxidation treatment. Different operating conditions, including pH, contact time and ASNase/MWCNT mass ratio, as well as the operational stability of the immobilized ASNase, were evaluated. For comparison purposes, data regarding the ASNase immobilization with pristine MWCNT was detailed. The characterization of the ASNase-MWCNT bioconjugate was addressed using different techniques, namely Transmission Electron Microscopy (TEM), Thermogravimetric Analysis (TGA) and Raman spectroscopy. Functionalized MWCNTs showed promising results, with an immobilization yield and a relative recovered activity of commercial ASNase above 95% under the optimized adsorption conditions (pH 8, 60 min of contact and 1.5 × 10-3 g mL-1 of ASNase). The ASNase-MWCNT bioconjugate also showed improved enzyme operational stability (6 consecutive reaction cycles without activity loss), paving the way for its use in industrial processes.

An environmental ecocorona influences the formation and evolution of the biological corona on the surface of single-walled carbon nanotubes

Nanomaterials (NMs) taken up from the environment carry a complex ecocorona consisting of dissolved organic matter. An ecocorona is assumed to influence the interactions between NMs and endogenous biomolecules and consequently affects the formation of a biological corona (biocorona) and the biological fate of the NMs. This study shows that biomolecules in fish plasma attach immediately (within <5 min) to the surface of SWCNTs and the evolution of the biocorona is a size dependent phenomenon. Quantitative proteomics data revealed that the nanotube size also influences the plasma protein composition on the surface of SWCNTs. The presence of a pre-attached ecocorona on the surface of SWCNTs eliminated the influence of nanotube size on the formation and evolution of the biocorona. Over time, endogenous biomolecules from the plasma partially replaced the pre-attached ecocorona as measured using a fluorescently labelled ecocorona. The presence of an ecocorona offers a unique surface composition to each nanotube. This suggests that understanding the biological fate of NMs taken up from the environment by organisms to support the environmental risk assessment of NMs is a challenging task because each NM may have a unique surface composition in the body of an organism.

Antimicrobial and anti-adhesive properties of carbon nanotube-based surfaces for medical applications: a systematic review

Although high-performance carbon materials are widely used in surface engineering, with emphasis on carbon nanotubes (CNTs), the application of CNT nanocomposites on medical surfaces is poorly documented. In this study, we aimed to evaluate the antimicrobial and anti-adhesive properties of CNT-based surfaces. For this purpose, a PRISMA-oriented systematic review was conducted based on predefined criteria and 59 studies were selected for the qualitative analysis. Results from the analyzed studies suggest that surfaces containing modified CNTs, and specially CNTs conjugated with different polymers, exhibited strong antimicrobial and anti-adhesive activities. These composites seem to preserve the CNT toxicity to microorganisms and promote CNT-cell interactions, as well as to protect them from nonspecific protein adsorption. However, CNTs cannot yet compete with the conventional strategies to fight biofilms as their toxicity profile on the human body has not been thoroughly addressed. This review can be helpful for the development of new engineered medical surfaces.

Inhibition of tau aggregation and associated cytotoxicity on neuron-like cells by calycosin

In this study, the in vitro assembly of tau and anti-amyloidogenic properties of one naturally occurring phytoestrogen, calycosin, was investigated by spectroscopic techniques including ThT and ANS fluorescence, CD, Congo red absorbance as well as TEM analysis. Afterwards the cytotoxicity of different amyloid species against SH-SY5Y cells was evaluated by MTT assay. Fluorescence spectroscopic studies revealed that calycosin exerts its anti-amyloidogenic effects through increasing the lag time and reducing the apparent growth rate constant (k_app), the amount of fibrillation, and the exposure of hydrophobic regions. Congo red absorbance and CD studies indicated that calycosin prevented the formation of tau aggregate species and β-sheets structures, respectively. TEM analysis also determined the capacity of calycosin to inhibit tau fibrillogenesis through formation of large amorphous aggregates. Furthermore, cellular assays disclosed that calycosin mitigated the cell mortality, LDH release, ROS level, and expression of Bax, Bcl-2, and Caspase-3 in both mRNA and protein levels induced by tau amyloid fibrils. In conclusion, this data may suggest that calycosin can prevent tau amyloid fibrillation and the associated cytotoxicity, mainly due to its effects on formation of lower content of oligomeric and fibrillar aggregates with lower solvent-exposed hydrophobic patches compared to those produced in the absence of calycosin.

Detection of food spoilage and adulteration by novel nanomaterial-based sensors

Food industry is always looking for more innovative and accurate ways to monitor the food safety and quality control of final products. Current detection techniques of analytes are costly and time-consuming, and occasionally require professional experts and specialized tools. The usage of nanomaterials in sensory systems has eliminated not only these drawbacks but also has advantages such as higher sensitivity and selectivity. This article first presents a general overview of the current studies conducted on the detection of spoilage and adulteration in foods from 2015 to 2020. Then, the sensory properties of nanomaterials including metal and magnetic nanoparticles, carbon nanostructures (nanotubes, graphene and its derivatives, and nanofibers), nanowires, and electrospun nanofibers are presented. The latest investigations and advancements in the application of nanomaterial-based sensors in detecting spoilage (food spoilage pathogens, toxins, pH changes, and gases) and adulterants (food additives, glucose, melamine, and urea) have also been discussed in the following sections. To conclude, these sensors can be applied in the smart packaging of food products to meet the demand of consumers in the new era.

Investigation of the Cellular Destination of Fluorescently Labeled Carbon Nanohorns in Cultured Cells

The high surface area, facile functionalization, and biocompatibility of carbon nanohorns (CNHs) make them attractive for many applications, including drug delivery. The cellular destination of nanomaterials dictates both the therapeutic application and the potential toxicity. Identifying the uptake mechanism is challenging as several endocytic pathways have been identified that facilitate cellular entry. Here, the cellular uptake of fluorescently labeled CNHs was assessed by utilizing quantitative cell-based assays to determine the factors influencing how internalization occurs and the destinations they reach in HeLa cells. Cell viability assays suggest that about 80% of the cells remained viable even at the highest concentration of 20 μg/mL exposure to CNHs. Uptake studies revealed that when pulse-chase conditions were applied, CNHs were seen to be localized both at the cell periphery and in a juxtanuclear pattern inside HeLa cells, in the latter case colocalizing with the lysosomal marker LAMP1. RNA interference studies, using a panel of RNA tools to individually deplete key molecules associated with the endocytic machinery, failed to block the internalization of CNHs into cells, suggesting that multiple mechanisms of endocytosis are used by this particle type.

Porous Carbon Microparticles as Vehicles for the Intracellular Delivery of Molecules

In this study the application of porous carbon microparticles for the transport of a sparingly soluble material into cells is demonstrated. Carbon offers an intrinsically sustainable platform material that can meet the multiple and complex requirements imposed by applications in biology and medicine. Porous carbon microparticles are attractive as they are easy to handle and manipulate and combine the chemical versatility and biocompatibility of carbon with a high surface area due to their highly porous structure. The uptake of fluorescently labeled microparticles by cancer (HeLa) and normal human embryonic Kidney (HEK 293) cells was monitored by confocal fluorescence microscopy. In this way the influence of particle size, surface functionalization and the presence of transfection agent on cellular uptake were studied. In the presence of transfection agent both large (690 nm) and small microparticles (250 nm) were readily internalized by both cell lines. However, in absence of the transfection agent the uptake was influenced by particle size and surface PEGylation with the smaller nanoparticle size being delivered. The ability of microparticles to deliver a fluorescein dye model cargo was also demonstrated in normal (HEK 293) cell line. Taken together, these results indicate the potential use of these materials as candidates for biological applications.

Potential of Microfluidics and Lab-on-Chip Platforms to Improve Understanding of "prion-like" Protein Assembly and Behavior

Human aging is accompanied by a relevant increase in age-associated chronic pathologies, including neurodegenerative and metabolic diseases. The appearance and evolution of numerous neurodegenerative diseases is paralleled by the appearance of intracellular and extracellular accumulation of misfolded proteins in affected brains. In addition, recent evidence suggests that most of these amyloid proteins can behave and propagate among neural cells similarly to infective prions. In order to improve understanding of the seeding and spreading processes of these "prion-like" amyloids, microfluidics and 3D lab-on-chip approaches have been developed as highly valuable tools. These techniques allow us to monitor changes in cellular and molecular processes responsible for amyloid seeding and cell spreading and their parallel effects in neural physiology. Their compatibility with new optical and biochemical techniques and their relative availability have increased interest in them and in their use in numerous laboratories. In addition, recent advances in stem cell research in combination with microfluidic platforms have opened new humanized in vitro models for myriad neurodegenerative diseases affecting different cellular targets of the vascular, muscular, and nervous systems, and glial cells. These new platforms help reduce the use of animal experimentation. They are more reproducible and represent a potential alternative to classical approaches to understanding neurodegeneration. In this review, we summarize recent progress in neurobiological research in "prion-like" protein using microfluidic and 3D lab-on-chip approaches. These approaches are driven by various fields, including chemistry, biochemistry, and cell biology, and they serve to facilitate the development of more precise human brain models for basic mechanistic studies of cell-to-cell interactions and drug discovery.

Protein-Nanoparticle Interaction: Corona Formation and Conformational Changes in Proteins on Nanoparticles

Nanoparticles (NPs) are highly potent tools for the diagnosis of diseases and specific delivery of therapeutic agents. Their development and application are scientifically and industrially important. The engineering of NPs and the modulation of their in vivo behavior have been extensively studied, and significant achievements have been made in the past decades. However, in vivo applications of NPs are often limited by several difficulties, including inflammatory responses and cellular toxicity, unexpected distribution and clearance from the body, and insufficient delivery to a specific target. These unfavorable phenomena may largely be related to the in vivo protein-NP interaction, termed "protein corona." The layer of adsorbed proteins on the surface of NPs affects the biological behavior of NPs and changes their functionality, occasionally resulting in loss-of-function or gain-of-function. The formation of a protein corona is an intricate process involving complex kinetics and dynamics between the two interacting entities. Structural changes in corona proteins have been reported in many cases after their adsorption on the surfaces of NPs that strongly influence the functions of NPs. Thus, understanding of the conformational changes and unfolding process of proteins is very important to accelerate the biomedical applications of NPs. Here, we describe several protein corona characteristics and specifically focus on the conformational fluctuations in corona proteins induced by NPs.

Surface Modification of Magnetic Nanoparticles by Carbon-Coating Can Increase Its Biosafety: Evidences from Biochemical and Neurobehavioral Tests in Zebrafish

Recently, magnetic nanoparticles (MNPs) have gained much attention in the field of biomedical engineering for therapeutic as well as diagnostic purposes. Carbon magnetic nanoparticles (C-MNPs) are a class of MNPs categorized as organic nanoparticles. C-MNPs have been under considerable interest in studying in various applications such as magnetic resonance imaging, photothermal therapy, and intracellular transportof drugs. Research work is still largely in progress for testing the efficacy of C-MNPs on the theranostics platform in cellular studies and animal models. In this study, we evaluated the neurobehavioral toxicity parameters on the adult zebrafish (Danio rerio) at either low (1 ppm) or high (10 ppm) concentration level of C-MNPs over a period of two weeks by waterborne exposure. The physical properties of the synthesized C-MNPs were characterized by transmission electron microscopy, Raman, and XRD spectrum characterization. Multiple behavior tests for the novel tank, mirror biting, predator avoidance, conspecific social interaction, shoaling, and analysis of biochemical markers were also conducted to elucidate the corresponding mechanism. Our data demonstrate the waterborne exposure of C-MNPs is less toxic than the uncoated MNPs since neither low nor high concentration C-MNPs elicit toxicity response in behavioral and biochemical tests in adult zebrafish. The approach combining biochemical and neurobehavioral approaches would be helpful for understanding C-MNPs association affecting the bioavailability, biosafety, interaction, and uptake of these C-MNPs in the living organism.

Distinct autophagy-apoptosis related pathways activated by Multi-walled (NM 400) and Single-walled carbon nanotubes (NIST-SRM2483) in human bronchial epithelial (16HBE14o-) cells

Given the recent development in the field of particle and fibre toxicology, parallels have been drawn between Carbon nanotubes (CNTs) and asbestos. It is now established that both multi-walled (MWCNTs) and single-walled (SWCNTs) carbon nanotubes might contribute to pulmonary disease. Although multiple mechanisms might be involved in CNT induced pathogenesis, systematic understanding of the relationship between different CNT exposure (MWCNT vs SWCNT) and autophagy/ apoptosis/ necrosis, in human lung epithelial cells remains limited. In this study, we demonstrate that exposure to MWCNT (NM-400), but not SWCNT (NIST-SRM2483), leads to an autophagic response after acute exposure (24 h). MWCNT exposure was characterized by an increase in anti-apoptotic BCL2, downregulation of executor Caspase-3/7 and increase in expression of genes from the autophagy machinery. For SWCNT exposure however, we observed an overexpression of executor Caspase-3/7 and upregulation of pro-apoptotic BAX; enrichment for processes like cornification, apoptotic process, cell differentiation from proteomic analysis. These results clearly indicate a major difference in the pathways initiated by the CNTs, in vitro. While the present study design provides mechanistic understanding after an acute exposure for the tested CNTs, we believe that the information obtained here would have relevance in better understanding of CNT toxicity and pathogenesis in general.

Functionalized, Vertically Super-Aligned Multiwalled Carbon Nanotubes for Potential Biomedical Applications

Currently, there is a lack of ultrasensitive diagnostic tool to detect some diseases such as ischemic stroke, thereby impacting effective and efficient intervention for such diseases at an embryonic stage. In addition to the lack of proper detection of the neurological diseases, there is also a challenge in the treatment of these diseases. Carbon nanotubes have a potential to be employed in solving the theragnostic challenges in those diseases. In this study, carbon nanotubes were successfully synthesized for potential application in the detection and treatment of the neurological diseases such as ischemic stroke. Vertically aligned multiwalled carbon nanotubes (VA-MWCNTs) were purified with HCl, carboxylated with H₂SO₄:HNO₃ (3:1) and acylated with SOCl₂ for use in potential targeting studies and for the design of a carbon-based electrode for possible application in the diagnosis of neurological diseases, including ischemic stroke. MWCNTs were washed, extracted from the filter membranes and dried in a vacuum oven at 60 °C for 24 h prior to functionalization and PEGylation. CNTs were characterized by SEM, TEM, OCA, DLS, CV and EIS. The HCl-treated CNT obtained showed an internal diameter, outer diameter and thickness of 8 nm, 34 nm and 75 µm, while these parameters for the H₂SO₄-HNO₃-treated CNT were 8 nm, 23 nm and 41µm, respectively. PEGylated CNT demonstrated zeta potential, polydispersive index and particle size distribution of 6 mV, 0.41 and 98 nm, respectively. VA-MWCNTs from quartz tube were successfully purified, carboxylated, acylated and PEGylated for potential functionalization for use in targeting studies. For designing the carbon-based electrode, VA-MWCNTs on silicon wafer were successfully incorporated into epoxy resin for diagnostic applications. Functionalized MWCNTs were nontoxic towards PC-12 neuronal cells. In conclusion, vertically super-aligned MWCNTs have been successfully synthesized and functionalized for possible theragnostic biomedical applications in neurological disorders such as ischemic stroke.

Quantitative Flow Cytometric Evaluation of Oxidative Stress and Mitochondrial Impairment in RAW 264.7 Macrophages after Exposure to Pristine, Acid Functionalized, or Annealed Carbon Nanotubes

Conventional nanotoxicological assays are subjected to various interferences with nanoparticles and especially carbon nanotubes. A multiparametric flow cytometry (FCM) methodology was developed here as an alternative to quantify oxidative stress, mitochondrial impairment, and later cytotoxic and genotoxic events. The experiments were conducted on RAW264.7 macrophages, exposed for 90 min or 24 h-exposure with three types of multiwalled carbon nanotubes (MWCNTs): pristine (Nanocyl™ CNT), acid functionalized (CNTf), or annealed treatment (CNTa). An original combination of reactive oxygen species (ROS) probes allowed the simultaneous quantifications of broad-spectrum ROS, superoxide anion (O₂^•-), and hydroxyl radical (•OH). All MWCNTs types induced a slight increase of broad ROS levels regardless of earlier antioxidant catalase activity. CNTf strongly stimulated the O₂^•- production. The •OH production was downregulated for all MWCNTs due to their scavenging capacity. The latter was quantified in a cell-free system by electron paramagnetic resonance spectroscopy (EPR). Further FCM-based assessment revealed early biological damages with a mitochondrial membrane potential collapse, followed by late cytotoxicity with chromatin decondensation. The combined evaluation by FCM analysis and cell-free techniques led to a better understanding of the impacts of MWCNTs surface treatments on the oxidative stress and related biological response.

Hybrid carbon-based materials for gene delivery in cancer therapy

Accumulation at tumor tissue without any damage to healthy normal tissues is an ultimate goal in cancer therapy. Despite many efforts in the field of cancer therapy, this disease remains as the major reason of mortality all over the world. Gene therapy has introduced great opportunity to fight against cancer disease. It should be noted that still some obstacles limit clinical application of gene delivery approach, which have to be overcome for efficient transportation of therapeutic gene to the site of action. In this regard, carbon nanomaterials and their unique physical and chemical properties such as their capability of DNA protection have attracted much attention in the field of nanomedicine and non-viral carriers for therapeutic genes. Although, negligible solubility of carbon nanomaterials in biological environments has limited their biomedical application but their structural characteristics facilitate their chemical modifications thereby overcoming their solubility problem. Moreover, hybridization of modified carbon materials with different polymers provides more biocompatible and capable systems for gene delivery purposes. In the current review, we summarized hybrid carbon-based materials as non-viral carriers for gene delivery.

Impacts of Organomodified Nanoclays and Their Incinerated Byproducts on Bronchial Cell Monolayer Integrity

Incorporation of engineered nanomaterials (ENMs) into nanocomposites using advanced manufacturing strategies is set to revolutionize diverse technologies. Of these, organomodified nanoclays (ONCs; i.e., smectite clays with different organic coatings) act as nanofillers in applications ranging from automotive to aerospace and biomedical systems. Recent toxicological evaluations increased awareness that exposure to ONC can occur along their entire life cycle, namely, during synthesis, handling, use, manipulation, and disposal. Compared to other ENMs, however, little information exists describing which physicochemical properties contribute to induced health risk. This study conducted high content screening on bronchial epithelial cell monolayers for coupled high-throughput in vitro assessment strategies aimed to evaluate acute toxicity of a library of ONCs (all of prevalent use) prior to and after simulated disposal by incineration. Coating-, incineration status-, and time-dependent effects were considered to determine changes in the pulmonary monolayer integrity, cell transepithelial resistance, apoptosis, and cell metabolism. Results showed that after exposure to each ONC at its half-maximal inhibitory concentration (IC₅₀) there is a material-induced toxicity effect with pristine nanoclay, for instance, displaying acute loss of monolayer coverage, resistance, and metabolism, coupled with increased number of apoptotic cells. Conversely, the other three ONCs tested displayed little loss of monolayer integrity; however, they exhibited differential coating-dependent increased apoptosis and up to 40-45% initial reduction in cell metabolism. Moreover, incinerated byproducts of ONCs exhibited significant loss of monolayer coverage and integrity, increased necrosis, with little evidence of monolayer re-establishment. These findings indicate that characteristics of organic coating type largely determine the mechanism of cytotoxicity and the ability of the monolayer to recover. Use of high content screening coupled with traditional in vitro assays proves to serve as a rapid pulmonary toxicity assessment tool to help define prevention by targeted physicochemical material properties design strategies.

A review on recent advancements in electrochemical biosensing using carbonaceous nanomaterials

This review, with 201 references, describes the recent advancement in the application of carbonaceous nanomaterials as highly conductive platforms in electrochemical biosensing. The electrochemical biosensing is described in introduction by classifying biosensors into catalytic-based and affinity-based biosensors and statistically demonstrates the most recent published works in each category. The introduction is followed by sections on electrochemical biosensors configurations and common carbonaceous nanomaterials applied in electrochemical biosensing, including graphene and its derivatives, carbon nanotubes, mesoporous carbon, carbon nanofibers and carbon nanospheres. In the following sections, carbonaceous catalytic-based and affinity-based biosensors are discussed in detail. In the category of catalytic-based biosensors, a comparison between enzymatic biosensors and non-enzymatic electrochemical sensors is carried out. Regarding the affinity-based biosensors, scholarly articles related to biological elements such as antibodies, deoxyribonucleic acids (DNAs) and aptamers are discussed in separate sections. The last section discusses recent advancements in carbonaceous screen-printed electrodes as a growing field in electrochemical biosensing. Tables are presented that give an overview on the diversity of analytes, type of materials and the sensors performance. Ultimately, general considerations, challenges and future perspectives in this field of science are discussed. Recent findings suggest that interests towards 2D nanostructured electrodes based on graphene and its derivatives are still growing in the field of electrochemical biosensing. That is because of their exceptional electrical conductivity, active surface area and more convenient production methods compared to carbon nanotubes. Graphical abstract Schematic representation of carbonaceous nanomaterials used in electrochemical biosensing. The content is classified into non-enzymatic sensors and affinity/ catalytic biosensors. Recent publications are tabulated and compared, considering materials, target, limit of detection and linear range of detection.

Vitamin K1 As A Potential Molecule For Reducing Single-Walled Carbon Nanotubes-Stimulated α-Synuclein Structural Changes And Cytotoxicity

Aims

Different kinds of vitamins can be used as promising candidates to mitigate the structural changes of proteins and associated cytotoxicity stimulated by NPs. Therefore, the structural changes of α-syn molecules and their associated cytotoxicity in the presence of SWCNTs either alone or co-incubated with vitamin K1 were studied by spectroscopic, bioinformatical, and cellular assays.

Methods

Intrinsic and ThT fluorescence, CD, and Congo red absorption spectroscopic approaches as well as TEM investigation, molecular docking, and molecular dynamics were used to explore the protective effect of vitamin K1 on the structural changes of α-syn induced by SWCNTs. The cytotoxicity of α-syn/SWCNTs co-incubated with vitamin K1 against SH-SY5Y cells was also carried out by MTT, LDH, and caspase-3 assays.

Results

Fluorescence spectroscopy showed that vitamin K1 has a significant effect in reducing SWCNT-induced fluorescence quenching and aggregation of α- syn. CD, Congo red adsorption, and TEM investigations determined that co-incubation of α- syn with vitamin K1 inhibited the propensity of α-syn into the structural changes and amorphous aggregation in the presence of SWCNT. Docking studies determined the occupation of preferred docked site of SWCNT by vitamin K1 on α- syn conformation. A molecular dynamics study also showed that vitamin K1 reduced the structural changes of α- syn induced by SWCNT. Cellular data exhibited that the cytotoxicity of α- syn co-incubated with vitamin K1 in the presence of SWCNTs is less than the outcomes obtained in the absence of the vitamin K1.

Conclusion

It may be concluded that vitamin K1 decreases the propensity of α- syn aggregation in the presence of SWCNTs and induction of cytotoxicity.

Single-walled carbon nanotubes repress viral-induced defense pathways through oxidative stress

Exposure of lung cells in vitro or mice to single-walled carbon nanotubes (SWCNTs) directly to the respiratory tract leads to a reduced host anti-viral immune response to infection with influenza A virus H1N1 (IAV), resulting in significant increases in viral titers. This suggests that unintended exposure to nanotubes via inhalation may increase susceptibility to notorious respiratory viruses that carry a high social and economic burden globally. However, the molecular mechanisms that contribute to viral susceptibility have not been elucidated. In the present study, we identified the retinoic acid-induced gene I (RIG-I) like receptors (RLRs)/mitochondrial antiviral signaling (MAVS) pathway as a target of SWCNT-induced oxidative stress in small airway epithelial cells (SAEC) that contribute to significantly enhanced influenza viral titers. Exposure of SAEC to SWCNTs increases viral titers while repressing several aspects of the RLR pathway, including mRNA expression of key genes (e.g. IFITs, RIG-I, MDA5, IFNβ1, CCL5). SWCNTs also reduce mitochondrial membrane potential without altering oxygen consumption rates. Our findings also indicate that SWCNTs can impair formation of MAVS prion-like aggregates, which is known to impede downstream activation of the RLR pathway and hence the transcriptional production of interferon-regulated anti-viral genes and cytokines. Furthermore, application of the antioxidant NAC alleviates inhibition of gene expression levels by SWCNTs, as well as MAVS signalosome formation, and increased viral titers. These data provide evidence of targeted impairment of anti-viral signaling networks that are vital to immune defense mechanisms in lung cells, contributing to increased susceptibility to IAV infections by SWCNTs.

Synthesis of carbon nanotubes using biochar as precursor material under microwave irradiation

Biochar is a carbon-rich porous material obtained by the thermochemical treatment of biomass. Biochar presents a suitable composition as precursor material for carbon nanotubes (CNTs) growth, and can be used as a sustainable alternative in the valorization of biomass. In this study, the synthesis of CNTs using biochar as biological precursor material is presented. CNTs were synthesized using a mixture of biochar and ferrocene including microwave assisted heating. Biochar samples used in the synthesis of CNTs were obtained from agroindustrial waste such as wheat straw, oat hulls, rapeseed cake and hazelnut hulls pyrolyzed at 400 °C and 600 °C. Synthesized CNTs were examined by dynamic light scattering, UV-VIS spectroscopy, Raman spectroscopy and transmission electron microscopy. The results indicate that the physicochemical properties of CNTs were influenced by pyrolysis temperature of biomass. Biochars obtained at 600 °C produced higher CNTs concentration and smaller hydrodynamic diameter. Moreover, CNTs synthesized from biochar of hazelnut hulls and wheat straw show a higher degree of wall graphitization, suggesting superior CNT quality. The results of this study show the feasible production of CNTs using biochar as precursor material.

Carbon nanotubes significantly enhance the biological activity of CpG ODN in chickens

Synthetic unmethylated cytidine-phosphate-guanosine oligodeoxynucleotides (CpG ODN) is an effective immune stimulant in chicken. To be effective CpG dosage requirement is high. High dosage increases cost of treatment and introduces toxicity. A delivery system using multi-walled carbon nanotubes (MWCNT) is utilized in this study to aid in lowering the effective dose of the immune stimulant. CpG ODNs were attached non-covalently in different ways to multi-walled carbon nanotubes (MWCNT). We assessed and selected an appropriate linking method of CpG ODN with MWCNT followed by cellular uptake studies to establish that MWCNT-conjugated CpG ODNs were delivered better than free CpG ODNs into the cell. It was observed that MWCNT-conjugated CpG ODNs were equally effective in priming the cells in vitro at 1000-fold less concentration than free CpG ODN. In vivo studies revealed that a significantly lower dose of CpG ODN, when given subcutaneously, was enough to protect chickens from a lethal challenge of bacteria. The mechanism of immune stimulation was examined by in vivo cell recruitment and in vitro cytokine production studies. MWCNT-conjugated CpG ODNs are significantly more efficacious and less toxic than free CpG ODN to qualify as a potential immune stimulant.

MWCNT interactions with protein: surface-induced changes in protein adsorption and the impact of protein corona on cellular uptake and cytotoxicity

PURPOSE

Protein adsorption onto nanoparticles in the form of protein corona, affects properties of nanomaterials and their behavior in the biological milieu. This study aims at exploring the effects of multiwalled carbon nanotubes (MWCNTs) surface chemistry on bovine serum albumin (BSA) and immunoglobulin G (IgG), including their adsorption behavior and spatial configurations, as well as the impact on cellular uptake, cytotoxicity, and cellular responses.

METHODS

Three types of MWCNTs (pristine MWCNTs, MWCNTs-COOH, and MWCNTs-PEG) were synthesized by classical chemical reduction. The size, morphology, hydrodynamic size, and zeta potential were characterized using transmission electron microscopy and dynamic light scattering. MWCNTs were exposed to BSA and IgG solutions, then the amount of MWCNT absorption was performed by bicinchoninic acid assay, and the effects were assessed by utilizing fluorescence spectroscopy, circular dichroism (CD) spectroscopy. Quantitative measurement of MWCNTs uptake with or without protein corona was performed as turbidity method. CCK assay and a microdilution method were performed to evaluate the effects of protein corona on cytotoxicity and pro-inflammatory cytokines release.

RESULTS

The BSA and IgG adsorption capacities of MWCNTs followed the order pristine MWCNTs>MWCNTs-COOH and MWCNTs-PEG. MWCNT binding can cause fluorescence quenching and conformational changes in BSA and IgG, indicating that both the physicochemical properties of MWCNTs and protein properties play critical roles in determining their adsorption behavior. Further study showed time-dependent increases in MWCNT cellular uptake and internalization. Hydrophobicity is the major factor increasing cellular uptake of pristine MWCNTs, but a protein corona enriched with dysoposnins is the main factor reducing uptake of MWCNT-COOH by RAW264.7 cells. The cytotoxicity and pro-inflammatory response related to physicochemical properties of MWCNTs, and frustrated phagocytosis is a key initiating event in the pro-inflammatory response of MWCNT-exposed macrophages.

CONCLUSION

These findings shed light on how functionalized MWCNTs interact with protein coronas and provide useful insight into the dramatic effect of protein coronas on different functionalized MWCNTs. These events affect cellular uptake and cytotoxicity, which could inform how to enhance MWCNT biocompatibility and develop approaches for managing MWCNT hazards.

An investigation into non-covalent functionalization of a single-walled carbon nanotube and a graphene sheet with protein G:A combined experimental and molecular dynamics study

Investigation of non-covalent interaction of hydrophobic surfaces with the protein G (PrG) is necessary due to their frequent utilization in immunosensors and ELISA. It has been confirmed that surfaces, including carbonous-nanostructures (CNS) could orient proteins for a better activation. Herein, PrG interaction with single-walled carbon nanotube (SWCNT) and graphene (Gra) nanostructures was studied by employing experimental and MD simulation techniques. It is confirmed that the PrG could adequately interact with both SWCNT and Gra and therefore fine dispersion for them was achieved in the media. Results indicated that even though SWCNT was loaded with more content of PrG in comparison with the Gra, the adsorption of the PrG on Gra did not induce significant changes in the IgG tendency. Several orientations of the PrG were adopted in the presence of SWCNT or Gra; however, SWCNT could block the PrG-FcR. Moreover, it was confirmed that SWCNT reduced the α-helical structure content in the PrG. Reduction of α-helical structure of the PrG and improper orientation of the PrG-SWCNT could remarkably decrease the PrG tendency to the Fc of the IgG. Importantly, the Gra could appropriately orient the PrG by both exposing the PrG-FcR and also by blocking the fragment of the PrG that had tendency to interact with Fab in IgG.

Amorphous aggregation of tau in the presence of titanium dioxide nanoparticles: biophysical, computational, and cellular studies

Background

Nanoparticles (NPs) when injected into the body can reach target tissues like nervous system and interact with tau proteins and neurons. This can trigger conformational changes of tau and may affect NP toxicity.

Methods

In this study, we used several biophysical techniques (extrinsic and intrinsic fluorescence spectroscopy, circular dichroism (CD) spectroscopy, ultraviolet (UV)-visible spectroscopy), transmission electron microscopy (TEM) investigations, molecular docking and molecular dynamics studies, and cellular assays [3-(4,5-Dimethylthiazol-2-Yl)-2,5-Diphenyltetrazolium Bromide (MTT) and flow cytometry) to reveal how structural changes of tau protein can change the cytotoxicity of titanium dioxide (TiO₂) NPs against neuron-like cells (SH-SY5Y) cells.

Results

It was shown that TiO₂ NPs result in hydrophilic interactions, secondary and tertiary structural changes, and the formation of amorphous tau aggregates. Conformational changes of tau increased the induced cytotoxicity by TiO₂ NPs. These data revealed that the denatured adsorbed protein on the NP surface may enhance NP cytotoxicity.

Conclusion

Therefore, this study provides useful insights on the NP-protein interactions and discusses how the protein corona can increase cytotoxicity to determine the efficacy of targeted delivery of nanosystems.

The impact of self-replicating proteins on inflammation, autoimmunity and neurodegeneration-An untraveled path

The central nervous system (CNS) in neurodegenerative diseases is a battlefield in which microglia fight a highly atypical battle. During the inflammatory process microglia themselves become dysfunctional and even with all the available immune arsenal including cytokine or/and antibody production, the battle is eventually lost. A closer look into the picture will reveal the fact that this is mainly due to the atypical characteristics of the infectious agent. The supramolecular assemblies of misfolded proteins carry unique features not encountered in any of the common pathogens. Through misfolding, proteins undergo conformational changes which make them become immunogenic, neurotoxic and highly infective. The immunogenicity appears to be triggered by the exposure of previously hidden hydrophobic portions in proteins which act as damage-associated molecular patters (DAMPs) for the immune system. The neurotoxicity and infectivity are promoted by the small oligomeric forms of misfolded proteins/peptides. Oligomers adopt conformations such as tubular-like, beta-barrel-like, etc., that penetrate cell membranes through their hydrophobic surfaces, thus destabilizing ionic homeostasis. At the same time, oligomers act as a seed for protein misfolding through a prion/prion-like mechanism. Here, we propose the hypothesis that oligomers have catalytic surfaces and exercise their capacity to infect native proteins through specific characteristics such as hydrophobic, electrostatic and π-π stacking interactions as well as the specific surface area (SSA), surface curvature and surface chemistry of their nanoscale supramolecular assemblies. All these are the key elements for prion/prion-like mechanism of self-replication and disease spreading within the CNS. Thus, understanding the mechanism of prion's templating activity may help us in the prevention and development of novel therapeutic strategies for neurodegenerative diseases.

Spectroscopic study of the loading of cationic porphyrins by carbon nanohorns as high capacity carriers of photoactive molecules to cells

Spherical carbon nanohorns have great potential as drug delivery agents. Here a detailed study of the loading of porphyrin molecules is reported and the influence on their stability described. An optimally loaded sample is shown to cause photoactivated cell death.

Albumin binding, anticancer and antibacterial properties of synthesized zero valent iron nanoparticles

BACKGROUND

Nanoparticles (NPs) have been emerging as potential players in modern medicine with clinical applications ranging from therapeutic purposes to antimicrobial agents. However, before applications in medical agents, some in vitro studies should be done to explore their biological responses.

AIM

In this study, protein binding, anticancer and antibacterial activates of zero valent iron (ZVFe) were explored.

MATERIALS AND METHODS

ZVFe nanoparticles were synthesized and fully characterized by X-ray diffraction, field-emission scanning electron microscope, and dynamic light scattering analyses. Afterward, the interaction of ZVFe NPs with human serum albumin (HSA) was examined using a range of techniques including intrinsic fluorescence, circular dichroism, and UV-visible spectroscopic methods. Molecular docking study was run to determine the kind of interaction between ZVFe NPs and HSA. The anticancer influence of ZVFe NPs on SH-SY5Y was examined by MTT and flow cytometry analysis, whereas human white blood cells were used as the control cell. Also, the antibacterial effect of ZVFe NPs was examined on Pseudomonas aeruginosa (ATCC 27853), Escherichia coli (ATCC 25922), and Staphylococcus aureus (ATCC 25923).

RESULTS

X-ray diffraction, transmission electron microscope, and dynamic light scattering analyses verified the synthesis of ZVFe NPs in a nanosized diameter. Fluorescence spectroscopy analysis showed that ZVFe NPs spontaneously formed a complex with HSA through hydrogen bonds and van der Waals interactions. Also, circular dichroism spectroscopy study revealed that ZVFe NPs did not change the secondary structure of HSA. Moreover, UV-visible data presented that melting temperature (Tm) of HSA in the absence and presence of ZVFe NPs was almost identical. Molecular dynamic study also showed that ZVFe NP came into contact with polar residues on the surface of HSA molecule. Cellular assays showed that ZVFe NPs can induce cell mortality in a dose-dependent manner against SH-SY5Y cells, whereas these NPs did not trigger significant cell mortality against normal white bloods in the concentration range studied (1-100 µg/mL). Antibacterial assays showed a noteworthy inhibition on both bacterial strains.

CONCLUSION

In conclusion, it was revealed that ZVFe NPs did not induce a substantial influence on the structure of protein and cytotoxicity against normal cell, whereas they derived significant anticancer and antibacterial effects.

Adsorption and in vitro release study of curcumin form polyethyleneglycol functionalized multi walled carbon nanotube: kinetic and isotherm study

Polyethylene glycol functionalized with oxygenated multi-walled carbon nanotubes (O-PEG-MWCNTs) as an efficient nanomaterial for the in vitro adsorption/release of curcumin (CUR) anticancer agent. The synthesized material was morphologically characterized using scanning electron microscopy, Fourier transform infrared spectroscopy and transmission electron microscopy. In addition, the CUR adsorption process was assessed with kinetic and isotherm models fitting well with pseudo-second order and Langmuir isotherms. The results showed that the proposed O-PEG-MWCNTs has a high adsorption capacity for CUR (2.0 × 10³ mg/g) based on the Langmuir model. The in vitro release of CUR from O-PEG-MWCNTs was studied in simulating human body fluids with different pHs (ABS pH 5, intestinal fluid pH 6.6 and body fluid pH 7.4). Lastly, to confirm the success compliance of the O-PEG-MWCNT nanocomposite as a drug delivery system, the parameters affecting the CUR release such as temperature and PEG content were investigated. As a result, the proposed nanocomposite could be used as an efficient carrier for CUR delivery with an enhanced prolonged release property. Graphical Abstract ᅟ.

Biophysical, molecular dynamics and cellular studies on the interaction of nickel oxide nanoparticles with tau proteins and neuron-like cells

Nickel oxide nanoparticles (NiO NPs) have been used in the biological and medical sciences. However, their toxic effects against biological systems such as nervous system have not been well studied. Therefore, the adverse effect of NiO NPs on tau structure was investigated by fluorescence and CD spectroscopic methods as well as TEM study. Also, molecular dynamic study was run to extend the experimental data. Cytotoxic activity of NiO NPs against SH-SY5Y cell was determined by trypan blue exclusion, cell morphology, ROS, and apoptosis assays. ANS, Nile red, ThT assays and electron micrograph investigation revealed that NiO NPs can increase the hydrophobic portions of tau and induce the formation of amorphous tau aggregates. Far and near CD spectroscopic methods revealed that NiO NPs can change the secondary and tertiary structure of tau, respectively. Theoretical studies depicted that NiO NPs lead to folding of tau structure. In the cellular view, NiO NPs induced significant mortality and morphological effects against SH-SY5Y cells. NiO NPs also provided a significant impact on generating intracellular ROS and apoptosis induction. This study determined that NiO NPs could mediate the induction of some undesired effects on the nervous system.

A biophysical study on the mechanism of interactions of DOX or PTX with α-lactalbumin as a delivery carrier

Doxorubicin and paclitaxel, two hydrophobic chemotherapeutic agents, are used in cancer therapies. Presence of hydrophobic patches and a flexible fold could probably make α-Lactalbumin a suitable carrier for hydrophobic drugs. In the present study, a variety of thermodynamic, spectroscopic, computational, and cellular techniques were applied to assess α-lactalbumin potential as a carrier for doxorubicin and paclitaxel. According to isothermal titration calorimetry data, the interaction between α-lactalbumin and doxorubicin or paclitaxel is spontaneous and the K (M^-1) value for the interaction of α-lactalbumin and paclitaxel is higher than that for doxorubicin. Differential scanning calorimetry and anisotropy results indicated formation of α-lactalbumin complexes with doxorubicin or paclitaxel. Furthermore, molecular docking and dynamic studies revealed that TRPs are not involved in α-Lac's interaction with Doxorubicin while TRP 60 interacts with paclitaxel. Based on Pace analysis to determine protein thermal stability, doxorubicin and paclitaxel induced higher and lower thermal stability in α-lactalbumin, respectively. Besides, fluorescence lifetime measurements reflected that the interaction between α-lactalbumin with doxorubicin or paclitaxel was of static nature. Therefore, the authors hypothesized that α-lactalbumin could serve as a carrier for doxorubicin and paclitaxel by reducing cytotoxicity and apoptosis which was demonstrated during our in vitro cell studies.