Organic Solvent-Free, One-Step Engineering of Graphene-Based Magnetic-Responsive Hybrids Using Design of Experiment-Driven Mechanochemistry

Graphene Oxide Nanosheets Toxicity in Mice Is Dependent on Protein Corona Composition and Host Immunity

Two-dimension graphene oxide (GO) nanosheets with high and low serum protein binding profiles (high/low hard-bound protein corona/HChigh/low) are used in this study as model materials and screening tools to investigate the underlying roles of the protein corona on nanomaterial toxicities in vivo. We proposed that the in vivo biocompatibility/nanotoxicity of GO is protein corona-dependent and host immunity-dependent. The hypothesis was tested by injecting HChigh/low GO nanosheets in immunocompetent ICR/CD1 and immunodeficient NOD-scid II2rγnull mice and performed histopathological and hematological evaluation studies on days 1 and 14 post-injection. HClow GO induced more severe acute lung injury compared to HChigh GO in both immunocompetent and immunodeficient mice, with the effect being particularly pronounced in immunocompetent animals. Additionally, HClow GO caused more significant liver injury in both types of mice, with immunodeficient mice being more susceptible to its hepatotoxic effects. Moreover, administration of HClow GO resulted in increased hematological toxicity and elevated levels of serum pro-inflammatory cytokines in immunocompromised and immunocompetent mice, respectively. Correlation studies were conducted to explore the impact of distinct protein corona compositions on resulting toxicities in both immunocompetent and immunodeficient mice. This facilitated the identification of consistent patterns, aligning with those observed in vitro, thus indicating a robust in vitro-in vivo correlation. This research will advance our comprehension of how hard corona proteins interact with immune cells, leading to toxicity, and will facilitate the development of improved immune-modulating nanomaterials for therapeutic purposes.

Macrophage derived Exosomal Docetaxel (Exo-DTX) for pro-metastasis suppression: QbD driven formulation development, validation, in-vitro and pharmacokinetic investigation

Exosomes, biogenic nano-vesicles, are renowned for their ability to encapsulate diverse payloads, however the systematic development and validation of exosomal formulation with significant biological implications have been overlooked. Herein, we developed and validated Exo-DTX, a QbD-driven optimized RAW 264.7 cell derived exosomal anti-cancer formulation of docetaxel (DTX) and evaluate its anti-metastatic and apoptotic efficacy in TNBC 4T1 cells. RAW264.7-derived exosomes were having particle size (112.5 ± 21.48 nm) and zeta-potential (-10.268 ± 3.66 mV) with polydispersity (PDI:0.256 ± 0.03). The statistical optimization of exosomes (200 μg) with Exo: DTX ratio 4:1 confirmed encapsulation of 23.60 ± 1.54 ng DTX/ µg exosomes. Exo-DTX (∼189 nm, -11.03 mV) with 100 ng/ml DTX as payload exhibited ∼5 folds' improvement in IC50 of DTX and distinct cytoskeletal deformation in TNBC 4T1 cells. It also has shown enormous Filamentous actin (F-actin) degradation and triggered apoptosis explained Exo-DTX's effective anti-migratory impact with just 2.6 ± 6.33 % wound closure and 4.56 ± 1.38 % invasion. The western blot confirmed that Exo-DTX downregulated migratory protein EGFR and β1-integrin but raised cleaved caspase 3/caspase 3 (CC3/C3) ratio and BAX/BCL-2 ratio by about 2.70 and 4.04 folds respectively. The naive RAW 264.7 exosomes also contributed positively towards the effect of Exo-DTX formulation by suppressing β1-integrin expression and increasing the CC3/C3 ratio in TNBC 4T1 cells as well. Additionally, significant improvement in PK parameters of Exo-DTX was observed in comparison to Taxotere, 6-folds and 3.04-folds improved t1/2 and Vd, proving the translational value of Exo-DTX formulation. Thus, the Exo-DTX so formulated proved beneficial in controlling the aggressiveness of TNBC wherein, naive exosomes also demonstrated beneficial synergistic anti-proliferative effect in 4T1.

Mechanochemistry: New Tools to Navigate the Uncharted Territory of "Impossible" Reactions

Mechanochemical transformations have made chemists enter unknown territories, forcing a different chemistry perspective. While questioning or revisiting familiar concepts belonging to solution chemistry, mechanochemistry has broken new ground, especially in the panorama of organic synthesis. Not only does it foster new "thinking outside the box", but it also has opened new reaction paths, allowing to overcome the weaknesses of traditional chemistry exactly where the use of well-established solution-based methodologies rules out progress. In this Review, the reader is introduced to an intriguing research subject not yet fully explored and waiting for improved understanding. Indeed, the study is mainly focused on organic transformations that, although impossible in solution, become possible under mechanochemical processing conditions, simultaneously entailing innovation and expanding the chemical space.

Solid-State Reaction Synthesis of Nanoscale Materials: Strategies and Applications

Nanomaterials (NMs) with unique structures and compositions can give rise to exotic physicochemical properties and applications. Despite the advancement in solution-based methods, scalable access to a wide range of crystal phases and intricate compositions is still challenging. Solid-state reaction (SSR) syntheses have high potential owing to their flexibility toward multielemental phases under feasibly high temperatures and solvent-free conditions as well as their scalability and simplicity. Controlling the nanoscale features through SSRs demands a strategic nanospace-confinement approach due to the risk of heat-induced reshaping and sintering. Here, we describe advanced SSR strategies for NM synthesis, focusing on mechanistic insights, novel nanoscale phenomena, and underlying principles using a series of examples under different categories. After introducing the history of classical SSRs, key theories, and definitions central to the topic, we categorize various modern SSR strategies based on the surrounding solid-state media used for nanostructure growth, conversion, and migration under nanospace or dimensional confinement. This comprehensive review will advance the quest for new materials design, synthesis, and applications.

Solvent-free mechanochemical preparation of graphene oxide-Fe3 O4 and its application in magnetic dispersive solid-phase extraction of illegal dyes in food samples

A simple, green, and efficient mechanochemical approach was developed herein to prepare tunable magnetic graphene oxide nanoparticles. The obtained nanoparticles were successfully used as adsorbents in a magnetic dispersive solid-phase extraction method to extract three cationic dyes (i.e., thioflavine T, auramine-O, and basic orange 2) found in food samples. Our proposed approach also utilized high-performance liquid chromatography with ultraviolet detection. Several key variables affecting the extraction recovery were investigated. These included the sample pH, amount of extractant, extraction time, sample volume, elution solvent type and volume, and the stability and reusability of the magnetic graphene oxide nanoparticles. Under optimized conditions, the calibration curve was linear at a concentration range of 0.005-1.0 μg/mL with a correlation coefficient of 0.9992-0.9996. Moreover, the limits of detection were determined at 0.97-1.35 μg/mL. The extraction mechanism was investigated via ultraviolet-visible spectrophotometry and zeta-potential analyses. The developed method was used to analyze the above-mentioned cationic dyes in bean products and yellow fish samples. Notably, satisfactory spiked recoveries ranging from 90.7 to 104.9% were achieved.

A multivariate approach to investigate the NMR CPMG pulse sequence for analysing low MW species in polymers

Detection and quantification of low molecular weight components in polymeric samples via nuclear magnetic resonance (NMR) spectroscopy can be difficult due to overlapping signal caused by line broadening characteristics of polymers. A way of overcoming this problem could be the exploitation of the difference in relaxation between small molecules and macromolecular species, such as the application of a T₂ filter by using the Carr-Purcell-Meiboom-Gill (CPMG) spin-echo pulse sequence. This technique, largely exploited in metabolomics studies, is applied here to material sciences. A Design of Experiments approach was used for evaluating the effect of different acquisition parameters (relaxation delay, echo time and number of cycles) and sample-related ones (concentration and polymer molecular weight) on selected responses, with a particular interest in performing a reliable quantitative analysis. Polymeric samples containing small molecules were analysed by NMR with and without the application of the filter, and analysis of variance was used to identify the most influential parameters. Results indicated that increasing the polymer concentration, hence sample viscosity, further attenuates polymer signals in CPMG experiments because the T₂ of those signals tends to decrease with increasing viscosity. The signal-to-noise ratio measured for small molecules can undergo a minimum loss when specific parameters are chosen in relation to the polymer molecular weight. Furthermore, the difference in dynamics between aliphatic and aromatic nuclei, as well as between mobile and stiff polymers, translates into different results in terms of polymer signal reduction, suggesting that the relaxation filter can also be used for obtaining information on the polymer structure.

Application of carbon nanotubes in cancer vaccines: Achievements, challenges and chances

Tumour-specific, immuno-based therapeutic interventions can be considered as safe and effective approaches for cancer therapy. Exploitation of nano-vaccinology to intensify the cancer vaccine potency may overcome the need for administration of high vaccine doses or additional adjuvants and therefore could be a more efficient approach. Carbon nanotube (CNT) can be described as carbon sheet(s) rolled up into a cylinder that is nanometers wide and nanometers to micrometers long. Stemming from the observed capacities of CNTs to enter various types of cells via diversified mechanisms utilising energy-dependent and/or passive routes of cell uptake, the use of CNTs for the delivery of therapeutic agents has drawn increasing interests over the last decade. Here we review the previous studies that demonstrated the possible benefits of these cylindrical nano-vectors as cancer vaccine delivery systems as well as the obstacles their clinical application is facing.

Protein-Corona-by-Design in 2D: A Reliable Platform to Decode Bio-Nano Interactions for the Next-Generation Quality-by-Design Nanomedicines

Hard corona (HC) protein, i.e., the environmental proteins of the biological medium that are bound to a nanosurface, is known to affect the biological fate of a nanomedicine. Due to the size, curvature, and specific surface area (SSA) 3-factor interactions inherited in the traditional 3D nanoparticle, HC-dependent bio-nano interactions are often poorly probed and interpreted. Here, the first HC-by-design case study in 2D is demonstrated that sequentially and linearly changes the HC quantity using functionalized graphene oxide (GO) nanosheets. The HC quantity and HC quality are analyzed using NanoDrop and label-free liquid chromatography-mass spectrometry (LC-MS) followed by principal component analysis (PCA). Cellular responses (uptake and cytotoxicity in J774 cell model) are compared using imaging cytometry and the modified lactate dehydrogenase assays, respectively. Cellular uptake linearly and solely correlates with HC quantity (R2 = 0.99634). The nanotoxicity, analyzed by retrospective design of experiment (DoE), is found to be dependent on the nanomaterial uptake (primary), HC composition (secondary), and nanomaterial exposure dose (tertiary). This unique 2D design eliminates the size-curvature-SSA multifactor interactions and can serve as a reliable screening platform to uncover HC-dependent bio-nano interactions to enable the next-generation quality-by-design (QbD) nanomedicines for better clinical translation.

Covalent mechanochemical functionalization of carbon-encapsulated iron nanoparticles towards the improvement of their colloidal stability

The mechanochemical covalent functionalization of carbon-encapsulated iron nanoparticles (CEINs) is reported. Unprotected sugars (mannose, galactose, β-cyclodextrin) and amino sugars (glucosamine and chitosan) were successfully conjugated to the surface of CEINs. The developed grinding-induced methods employ (i) the 1,3-dipolar cycloadditions of nitrile oxides or azomethine ylides and (ii) amidation-type reactions with the inclusion of carboxyl-functionalized CEINs and amino sugars. All the developed mechanochemical processes are fast (reaction time 10 min) and result in high degrees of coverage (7.3-31.5 wt%). The presented functionalization routes also constitute easy to perform and environmentally improved protocols. Moreover, the use of toxic organic solvents is not required. A comprehensive study on the colloidal stability of the sugar-functionalized CEINs is also included in this work. The results of the turbidimetric analyses reveal that both grinding-induced formation of amide bonds and the cycloadditions of sugar moieties to the surface of CEINs result in the significant improvement of their colloidal stability. The highest stability of the aqueous dispersion was found for CEINs functionalized with β-cyclodextrin. The comparative studies between the classical wet approach and the grinding-induced functionalization of CEINs show that the herein developed environmentally improved method increases the colloidal stability three times. The crucial role of the mechanochemical approach in the covalent functionalization of CEINs and the improvement of their colloidal stability is discussed in this work.

Solventless mechanochemical preparation of novel magnetic bioconjugates

A solventless mechanochemical approach was employed to obtain a bioconjugate (BSA-DA-Fe₂O₃) based on bovine serum albumin (BSA) and dopamine (DA) coated iron oxide magnetic nanoparticles. UV-vis measurements of the obtained material showed a distinctive peak at 280 nm which, together with the presence of N on the surface of the nanomaterial (a band at 400 eV in the XPS spectrum) and zeta potential measurements, confirmed the successful immobilization of the protein. Additionally, the presence of two bands at 1652 and 1545 cm^-1 in the FT-IR spectra of both BSA and BSA-DA-Fe₂O₃ and steady-state fluorescence analysis validated that the protein preserved its native-like structure after the mechanochemical milling process. Also the functionalized MNPs preserved their magnetic properties as have been demonstrated by their magnetic susceptibility value.

New bio-nanocomposites based on iron oxides and polysaccharides applied to oxidation and alkylation reactions

Polysaccharides from natural sources and iron precursors were applied to develop new bio-nanocomposites by mechanochemical milling processes. The proposed methodology was demonstrated to be advantageous in comparison with other protocols for the synthesis of iron oxide based nanostructures. Additionally, mechanochemistry has enormous potential from an environmental point-of-view since it is able to reduce solvent issues in chemical syntheses. The catalytic activity of the obtained nanocatalysts was investigated in both the oxidation of benzyl alcohol to benzaldehyde and in the alkylation of toluene with benzyl chloride. The microwave-assisted oxidation of benzyl alcohol reached 45% conversion after 10 min. The conversion of the alkylation of toluene in both microwave-assisted and conventional heating methods was higher than 99% after 3 min and 30 min, respectively. The transformation of benzyl alcohol and toluene into valuable product in both the oxidation and alkylation reaction reveals a potential method for the valorization of lignocellulosic biomass.

Synthesis and Supercapacitor Application of Alkynyl Carbon Materials Derived from CaC2 and Polyhalogenated Hydrocarbons by Interfacial Mechanochemical Reactions

The discovery of new carbon materials and the reactive activation of CaC₂ are challenging subjects. In this study, a series of alkynyl carbon materials (ACMs) were synthesized by the interfacial mechanochemical reaction of CaC₂ with four typical polyhalogenated hydrocarbons. Their properties and structures were characterized, and their electrochemical performances were examined. The reaction was rapid and efficient arising from the intense mechanical activation of CaC₂. The ACMs are micro-mesoporous materials with distinct layered structure, specific graphitization degree, and clear existence of sp-C. In addition, the ACMs exhibit high specific capacitance in the range of 57-133 F g^-1 and thus can be ideal candidates for active materials used in supercapacitors. The results may imply an alternative synthesis of carbon allotropes, as well as an efficient approach for the activation of CaC₂.

Synthesis of double-clickable functionalised graphene oxide for biological applications

Azide- and alkyne-double functionalised graphene oxide (Click(2) GO) was synthesised and characterised with attenuated total reflectance Fourier transform infrared spectroscopy (ATR-FTIR), thermogravimetric analysis (TGA) and Raman spectroscopy. Fourteen-percentage increase in azide content was found, after pre-treatment of GO with meta-chloroperoxybenzoic acid (mCPBA), determined with elemental analysis. No effect on A549 cell viability was found, up to 100 μg mL(-1) and 72 h of incubation, determined with the modified lactate dehydrogenase (mLDH) assay. Two sequential copper(i) catalysed azide-alkyne cycloaddition (CuAAC) reactions were performed to conjugate the propargyl-modified blood-brain barrier targeting peptide Angiopep-2, and a bis-azide polyethylene glycol (MW = 3500), to the Click(2) GO. The final conjugate was characterised with ATR-FTIR and TGA.

Solvent-Free Click-Mechanochemistry for the Preparation of Cancer Cell Targeting Graphene Oxide

Polyethylene glycol-functionalized nanographene oxide (PEGylated n-GO) was synthesized from alkyne-modified n-GO, using solvent-free click-mechanochemistry, i.e., copper(I)-catalyzed azide-alkyne cycloaddition (CuAAC). The modified n-GO was subsequently conjugated to a mucin 1 receptor immunoglobulin G antibody (anti-MUC1 IgG) via thiol-ene coupling reaction. n-GO derivatives were characterized with Fourier-transformed infrared (FT-IR) spectroscopy, thermogravimetric analysis (TGA), Bradford assay, sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE), and atomic force microscopy (AFM). Cell targeting was confirmed in vitro in MDA-MB-231 cells, either expressing or lacking MUC1 receptors, using flow cytometry, confocal laser scanning microscopy (CLSM) and multiphoton (MP) fluorescence microscopy. Biocompatibility was assessed using the modified lactate dehydrongenase (mLDH) assay.