Permanent agglomerates in powdered nanoparticles: Formation and future prospects

Multifaceted evaluation of pyrazole derivative (T4)-chitosan (CS) nanoparticles: Morphology, drug release, and anti-tumor efficacy in a rat model

The development of targeted nanotherapeutics has emerged as a pivotal advancement in cancer treatment, aiming to enhance the efficacy and specificity of drug delivery while minimizing systemic toxicity. Due to their biocompatibility and modifiable surface properties, Chitosan-based nanoparticles have shown considerable promise in encapsulating and delivering therapeutic agents directly to tumor sites. This study investigates the potential of 1,5-diary pyrazole derivative (T4)-loaded chitosan (CS) nanoparticles as a novel anticancer agent, evaluating their physical characteristics, in vivo biodistribution, and therapeutic efficacy against cancerous cells. SEM morphological analysis confirmed chitosan-based nanoparticles' smooth, spherical structure, with aggregation patterns typical of high surface energy nanoparticle synthesis. UV-visible spectroscopy and XRD analysis validated the successful incorporation of T4, showing characteristic absorption peaks and indicating a reduction in crystallinity desirable for enhanced drug release. In vivo imaging demonstrated the rapid systemic distribution of T4-CS nanoparticles, essential for delivering therapeutic agents effectively. The cytotoxic potential of T4-CS nanoparticles was significantly higher against cancer cells compared to controls, confirmed by MTT and scratch assays, indicating enhanced anti-cancer activity and potential inhibition of cancer metastasis. Furthermore, histological and gene expression analyses supported the anti-tumor and pro-apoptotic capabilities of T4-CS nanoparticles, showing reduced proliferation markers and inflammatory pathways. Behavioral assessments in rats highlighted the neuroprotective effects of T4-CS nanoparticles against 7,12-dimethyl benzanthracene (DMBA) induced neurotoxicity, suggesting their utility as both anticancer and neuroprotective agents. This multifaceted evaluation underscores the versatility and therapeutic potential of T4-CS nanoparticles, warranting further investigation into their mechanistic effects and clinical applications.

In Situ Reactive Printing of Aluminum Matrix Composite with Ultra-High Volume Fraction Reinforcement

Additive manufacturing (AM) can fabricate intricate structures that are infeasible or uneconomical for conventional manufacturing methods. Its unique capabilities have motivated emergence of several printing technologies and extensive research in material adoption in particular ferrous-, Ti-, and Ni-based alloys. Meanwhile, the large freezing range and high reflectivity of aluminum, a lightweight structural material, greatly reduce aluminum's compatibility with AM. The incompatibility roots from aluminum's unstable behavior in the rapid cyclic thermal conditions in AM and its poor interaction with laser. This hinders the development of laser-based aluminum AM and deteriorates the existing lack of lightweight structural materials in the intermediate temperature range. Aluminum matrix composites (AMCs) have great potential to serve as thermally stable lightweight structural materials, combining lightweight nature of aluminum matrix and strength of reinforcement phases. However, fabrication of AMC largely uses conventional methods, achieving only moderate volume fraction of reinforcement while having limited part complexity compared with AM. To address these challenges, in situ reactive printing (IRP) is adopted as a novel AM method, harnessing the reaction product of dissimilar elemental powder mix to fabricate AMC with an ultra-high volume fraction of intermetallic reinforcement. In this study, the effect of titanium addition to elemental aluminum feedstock powder is systematically studied on different aspects, including material processability, microstructural features, and mechanical performances. The results show that IRP can overcome the incompatibility between AM and aluminum and produce AMC with exceptional volume fraction of reinforcements and outstanding stiffness enhancement when compared with existing AM aluminum alloys and other AMCs.

Dispersion and Homogeneity of MgO and Ag Nanoparticles Mixed with Polymethylmethacrylate

This study aims to examine the impact of the direct and indirect mixing techniques on the dispersion and homogeneity of magnesium oxide (MgO) and silver (Ag) nanoparticles (NPs) mixed with polymethylmethacrylate (PMMA). NPs were mixed with PMMA powder directly (non-ethanol-assisted) and indirectly (ethanol-assisted) with the aid of ethanol as solvent. X-ray diffraction (XRD), energy-dispersive X-ray spectroscopy (EDX), and scanning electron microscope (SEM) were used to evaluate the dispersion and homogeneity of MgO and Ag NPs within the PMMA-NPs nanocomposite matrix. Prepared discs of PMMA-MgO and PMMA-Ag nanocomposite were analyzed for dispersion and agglomeration by Stereo microscope. XRD showed that the average crystallite size of NPs within PMMA-NP nanocomposite powder was smaller in the case of ethanol-assisted mixing compared to non-ethanol-assisted mixing. Furthermore, EDX and SEM revealed good dispersion and homogeneity of both NPs on PMMA particles with ethanol-assisted mixing compared to the non-ethanol-assisted one. Again, the PMMA-MgO and PMMA-Ag nanocomposite discs were found to have better dispersion and no agglomeration with ethanol-assisted mixing when compared to the non-ethanol-assisted mixing technique. Ethanol-assisted mixing of MgO and Ag NPs with PMMA powder obtained better dispersion, better homogeneity, and no agglomeration of NPs within the PMMA-NP matrix.

Colloidal Stabilization of Submicron-Sized Zeolite NaA in Ethanol-Water Mixtures for Nanostructuring into Thin Films and Nanofibers

Despite the growing use of organic or mixed solvents in zeolite processing, most studies focus only on aqueous suspension systems. We investigated the colloidal characteristics of submicron-sized zeolite NaA in mixed ethanol-water solvents. The effects of the mixing ratio of solvents and various additives on the dispersion of the zeolite powders were studied. The zeolite NaA particles were destabilized in solvent mixtures at a high ethanol-to-water ratio, a reduction in the zeta potential was observed, and the destabilization was rationalized by the Derjaguin, Landau, Verwey, Overbeek (DLVO) theory. An improved stabilization of the zeolite NaA suspensions was achieved in ethanol-rich solvent mixtures using nonionic low molecular weight organic additives, but not with their ionic counterparts such as anionic, cationic surfactants or inorganic acids or bases. Polyethylene glycol (PEG)-400 was found to be a good dispersant for the submicron-sized zeolite NaA particles in the ethanol-water mixtures, which was attributed to its interaction with the zeolite surface, leading to an increased zeta potential. The PEG-stabilized zeolite suspensions led to low suspension viscosities as well as uniform and consistent spin-coated films.

Cryogrinding and sieving techniques as challenges towards producing controlled size range microplastics for relevant ecotoxicological tests

The impact of microplastics (MP) has attracted much attention from the scientific community and many laboratory assessments have been made of their effects on aquatic organisms. To produce MP from real environmental plastic waste, which would enable more realistic experiments, we used plastic pearl farming equipment from French Polynesian lagoons. Here, the pearl oyster Pinctada margaritifera could encounter MP coming from their breakdown in its surrounding environment. We tested an established method based on mechanical cryogenic grinding and liquid sieving. Our desired size range was 20-60 μm, corresponding to the optimal particle size ingested by P. margaritifera. The protocol was effective, generating MP particles of 20-60 μm (∼17,000-28,000 MP μg^-1), but also produced too many smaller particles. The peak in the desired size range was thus flattened by the many small particles <3 μm (∼82,000-333,000 MP μg^-1; 53-70% of total analysed particles), visible at the limit of Coulter counter analysis (cut-off point: 2 μm). Laser diffraction analysis (cut-off point: 0.4 μm) provided greater detail, showing that ∼80-90% of the total analysed particles were <1 μm. Diverging particle size distributions between those expected based on sieving range and those really observed, highlight the need to perform fine-scaled particle size distribution analyses to avoid underestimating the number of small micro- and nanoplastics (MNP) and to obtain an exact estimation of the fractions produced. Size and microstructure characterization by scanning electron microscopy suggested spontaneous particle self-assembly into crystal superstructures, which is the supposed cause of the divergence we observed. Overall, our results emphasize that particle self-assembly is a technical hurdle requiring further work and highlight the specific need to finely characterize the size distribution of MNP used in ecotoxicological experiments to avoid overestimating effects.

Modelling Thermal Conduction in Polydispersed and Sintered Nanoparticle Aggregates

Nanoparticle aggregation has been found to be crucial for the thermal properties of nanofluids and their performance as heating or cooling agents. Most relevant studies in the literature consider particles of uniform size with point contact only. A number of forces and mechanisms are expected to lead to deviation from this ideal description. In fact, size uniformity is difficult to achieve in practice; also, overlapping of particles within aggregates may occur. In the present study, the effects of polydispersity and sintering on the effective thermal conductivity of particle aggregates are investigated. A simulation method has been developed that is capable of producing aggregates made up of polydispersed particles with tailored morphological properties. Modelling of the sintering process is implemented in a fashion that is dictated by mass conservation and the desired degree of overlapping. A noticeable decrease in the thermal conductivity is observed for elevated polydispersity levels compared to that of aggregates of monodisperse particles with the same morphological properties. Sintered nanoaggregates offer wider conduction paths through the coalescence of neighbouring particles. It was found that there exists a certain sintering degree of monomers that offers the largest improvement in heat performance.

Palladium Nanoparticles Functionalized with PVP-Quercetin Inhibits Cell Proliferation and Activates Apoptosis in Colorectal Cancer Cells

Nanotechnology is focused on the development and application of novel nanomaterials with particular physicochemical properties. Palladium nanoparticles (PdNPs) have been used as antimicrobials, antifungals, and photochemicals and for catalytic activity in dye reduction. In the present investigation, we developed and characterized PdNPs as a carrier of quercetin and initiated a study of its effects in colorectal cancer cells. PdNPs were first functionalized with polyvinylpyrrolidone (PVP) and then coupled to quercetin (PdNPs-PVP-Q). Our results showed that quercetin was efficiently incorporated to PdNPs-PVP, as demonstrated using UV/Vis and FT-IR spectroscopy. Using transmission electron microscopy, we demonstrated a reduction in size from 3–14.47 nm of PdNPs alone to 1.8–7.4 nm of PdNPs-PVP and to 2.12–3.14 of PdNPs-PVP-Q, indicating an increase in superficial area in functionalized PdNPs-Q. Moreover, hydrodynamic size studies using dynamic light scattering showed a reduction in size from 2120.33 nm ± 112.53 with PdNPs alone to 129.96 nm ± 6.23 for PdNPs-PVP-Q, suggesting a major reactivity when quercetin is coupled to nanoparticles. X-ray diffraction assays show that the addition of PVP or quercetin to PdNPs does not influence the crystallinity state. Catalytic activity assays of PdNPs-PVP-Q evidenced the chemical reduction of 4-nitrophenol, methyl orange, and methyl blue, thus confirming an electron acceptor capacity of nanoparticles. Finally, biological activity studies using MTT assays showed a significant inhibition (p < 0.05) of cell proliferation of HCT-15 colorectal cancer cells exposed to PdNPs-PVP-Q in comparison to untreated cells. Moreover, treatment with PdNPs-PVP-Q resulted in the apoptosis activation of HCT-15 cells. In conclusion, here we show for the first time the development of PdNPs-PVP-Q and evidence its biological activities through the inhibition of cell proliferation and apoptosis activation in colorectal cancer cells in vitro.

Highly Dispersed Ag2S Nanoparticles: In Situ Synthesis, Size Control, and Modification to Mechanical and Tribological Properties towards Nanocomposite Coatings

A facile in situ synthesis approach and a size control strategy were established to obtain Ag₂S nanoparticles in polyimide (PI) composite coatings. Such Ag₂S nanoparticles in the composite coatings were characterized, and the effects of the as-obtained Ag₂S nanoparticles of different sizes on the mechanical and tribological properties of the nanocomposite coatings were investigated. Results indicate that the in situ synthesized Ag₂S nanoparticles exhibited good dispersibility and bimodal and multimodal size distribution in the nanocomposite coatings. The size of the Ag₂S nanoparticles can be effectively controlled by adjusting the substituent alkyl chain length of single-source precursor, and these Ag₂S nanoparticles exhibited superior improvement to mechanical and tribological properties of the nanocomposite coatings. More importantly, the Ag₂S nanoparticles with the proper grain size and bimodal size distribution provided the optimal mechanical and tribological properties for the nanocomposite coatings, and the excellent tribological properties were attributed to their outstanding mechanical properties and strong ability to form a homogenous and stable protective tribofilm.

EDTA etching: a simple way for regulating the traps, size and aqueous-dispersibility of Cr3+-doped zinc gallate

EDTA etching, the first strategy that simply generates deep traps while reducing the size and improving the aqueous-dispersibility, is presented.

Traps, size and aqueous-dispersibility are the most important parameters that affect the features and applications of persistent luminescent nanoparticles (PLNPs). However, simultaneous controlling of these parameters is rather difficult and has not been reported yet. We present the first exploration on adjusting the traps, size and aqueous-dispersibility of PLNPs via simple ethylenediaminetetraacetate (EDTA) etching. Cr_0.004³⁺:ZnGa₂O₄ (ZGO) was used as the PLNP model. EDTA etching of the sintered ZGO results in effective reduction of the size and great improvement in the aqueous-dispersibility. In addition, EDTA etching alters the density of mediate traps and generates new deep traps, thus achieving the massive production of (ultra)small ZGO–EDTA with fine aqueous-dispersibility, suitable mediate/deep traps and superlong bright afterglows (51 days). As EDTA can interact with most metals, this simple EDTA etching strategy is prospectively amenable to other PLNPs, and the resulting PLNPs–EDTA have wide applications in both biological field and information storage.

Interaction of silica nanoparticles with tau proteins and PC12 cells: Colloidal stability, thermodynamic, docking, and cellular studies

Study on the side effects of the nanoparticles (NPs) can provide useful information regarding their biological and medical applications. Herein, the colloidal stability of the silicon dioxide NPs (SiO₂ NPs) in the absence and presence of tau was investigated by TEM and DLS techniques. Afterwards, the thermodynamic parameters of interaction between SiO₂ NPs and tau were determined by fluorescence spectroscopy and docking studies. Finally, the cytotoxic effects of SiO₂ NPs on the viability of PC12 cells were investigated by MTT, AO/EB staining and flow cytometry assays. TEM, DLS, and zeta potential investigations revealed that tau can reduce the colloidal stability of SiO₂ NPs. Fluorescence spectroscopy study indicated that SiO₂ NPs bound to the tau with high affinity through hydrogen bonds and van der Waals interactions. Docking study also determined that Ser, Thr and Tyr residues provide a polar microenvironment for SiO₂ NPs/tau interaction. Cellular studies demonstrated that SiO₂ NPs can induce cell mortality through both apoptosis and necrosis mechanisms. Therefore, it may be concluded that the biological systems such as nervous system proteins can affect the colloidal stability of NPs and vice versa NPs in the biological systems can bind to proteins and cell membranes non-specifically and may induce toxicity.

Metal Nanoparticles: Thermal Decomposition, Biomedicinal Applications to Cancer Treatment, and Future Perspectives

Monodispersed forms of metal nanoparticles are significant to overcome frightening threat of cancer. This review examined pragmatically thermal decomposition as one of the best ways to synthesize monodispersed metal nanoparticles which are stable and of small particle sizes. Controlled morphology for delivery of anticancer agent to specific cells can also be obtained with thermal decomposition. In addition to thermal decomposition, the study also looked into processes of characterization techniques, biological evaluation, toxicity of nanoparticles, and future perspectives.