Aggregation behaviour of black carbon in aquatic solution: Effect of ionic strength and coexisting metals

Aggregation kinetics of diesel soot nanoparticles in lung fluids: Effects of exposure conditions, fluid properties, and pulmonary surfactant lipids

Soot nanoparticles (SNPs) are carbonaceous particulate matter with significant environmental and health impacts. Once inhaled, their aggregation in the respiratory system can influence their migration patterns and health hazards. This study investigated the effects of exposure conditions (interaction time, particle concentration, and activity state), fluid properties (pH and composition), and pulmonary surfactant lipids [micro-sized (m-DPPC) and nano-sized dipalmitoylphosphatidylcholine (n-DPPC)] on aggregation kinetics of SNPs in five lung fluids. Early-stage aggregation rates ranked artificial lysosomal fluid (0.64 nm/s) > simulated alveolar fluid (0.20 nm/s) > simulated lung fluid (0.17 nm/s) > simulated serum (0.11 nm/s) > Gamble's solution (0.03 nm/s), indicating potential SNP migration into the lower respiratory tract and alveolar interstitial spaces. Increasing particle concentration and reducing pH both promoted aggregation. Under static conditions, SNPs formed larger aggregates (397.8-5441 nm) than dynamic conditions (209.7-2461 nm) across all lung fluids over 24 h. Aggregation was driven by Ca2 +, Mg2+, citric acid, sodium lactate, sodium citrate, and glycine. Among two lipids, m-DPPC facilitated aggregation through charge neutralization and bridging adsorption, while n-DPPC inhibited aggregation via steric hindrance, consistent with the modified Derjaguin-Landau-Verwey-Overbeek (MDLVO) theory. These findings underscore the significant impact of lung fluids on migration and risks of SNPs in respiratory systems.

Piezoresistive, Piezocapacitive and Memcapacitive Silk Fibroin-Based Cement Mortars

Water-stable proteins may offer a new field of applications in smart materials for buildings and infrastructures where hydraulic reactions are involved. In this study, cement mortars modified through water-soluble silk fibroin (SF) are proposed. Water-soluble SF obtained by redissolving SF films in phosphate buffer solution (PBS) showed the formation of a gel with the β sheet features of silk II. Electrical measurements of SF indicate that calcium ions are primarily involved in the conductivity mechanism. By exploiting the water solubility properties of silk II and Ca2+ ion transport phenomena as well as their trapping effect on water molecules, SF provides piezoresistive and piezocapacitive properties to cement mortars, thus enabling self-sensing of mechanical strain, which is quite attractive in structural health monitoring applications. The SF/cement-based composite introduces a capacitive gauge factor which surpasses the traditional resistive gauge factor reported in the literature by threefold. Cyclic voltammetry measurements demonstrated that the SF/cement mortars possessed memcapacitive behavior for positive potentials near +5 V, which was attributed to an interfacial charge build-up modulated by the SF concentration and the working electrode. Electrical square-biphasic excitation combined with cyclic compressive loads revealed memristive behavior during the unloading stages. These findings, along with the availability and sustainability of SF, pave the way for the design of novel multifunctional materials, particularly for applications in masonry and concrete structures.

Heteroaggregation kinetics of nanoplastics and soot nanoparticles in aquatic environments

Heteroaggregation between polystyrene nanoplastics (PSNPs) and soot nanoparticles (STNPs) in aquatic environments may affect their fate and transport. This study investigated the effects of particle concentration ratio, electrolytes, pH, and humic acid on their heteroaggregation kinetics. The critical coagulation concentration (CCC) ranked CCCPSNPs > CCCPSNPs-STNPs > CCCSTNPs, indicating that heteroaggregation rates fell between homoaggregation rates. In NaCl solution, as the PSNPs/STNPs ratio decreased from 9/1 to 3/7, heteroaggregation rate decreased and CCCPSNPs-STNPs increased from 200 to 220 mM due to enhanced electrostatic repulsion. Outlier was observed at PSNPs/STNPs= 1/9, where CCCPSNPs-STNPs= 170 mM and homoaggregation of STNPs dominated. However, in CaCl2 solution where calcium bridged with STNPs, heteroaggregation rate increased and CCCPSNPs-STNPs decreased from 26 to 5 mM as the PSNPs/STNPs ratio decreasing from 9/1 to 1/9. In composite water samples, heteroaggregation occurred only at estuarine and marine salinities. Acidic condition promoted heteroaggregation via charge screening. Humic acid retarded or promoted heteroaggregation in NaCl or CaCl2 solutions by steric hindrance or calcium bridging, respectively. Other than van der Waals attraction and electrostatic repulsion, heteroaggregation was affected by steric hindrance, hydrophobic interactions, π - π interactions, and calcium bridging. The results highlight the role of black carbon on colloidal stability of PSNPs in aquatic environments.

Carbon Nanomaterials for Plant Priming through Mechanostimulation: Emphasizing the Role of Shape

The use of nanomaterials to improve plant immunity for sustainable agriculture is gaining increasing attention; yet, the mechanisms involved remain unclear. In contrast to metal-based counterparts, carbon-based nanomaterials do not release components. Determining how these carbon-based nanomaterials strengthen the resistance of plants to diseases is essential as well as whether shape influences this process. Our study compared single-walled carbon nanotubes (SWNTs) and graphene oxide (GO) infiltration against the phytopathogen Pseudomonas syringae pv tomato DC3000. Compared with plants treated with GO, plants primed with SWNTs showed a 29% improvement in the pathogen resistance. Upon nanopriming, the plant displayed wound signaling with transcriptional regulation similar to that observed under brushing-induced mechanostimulation. Compared with GO, SWNTs penetrated more greatly into the leaf and improved transport, resulting in a heightened wound response; this effect resulted from the tubular structure of SWNTs, which differed from the planar form of GO. The shape effect was further demonstrated by wrapping SWNTs with bovine serum albumin, which masked the sharp edges of SWNTs and resulted in a significant decrease in the overall plant wound response. Finally, we clarified how the local wound response led to systemic immunity through increased calcium ion signaling in distant plant areas, which increased the antimicrobial efficacy. In summary, our systematic investigation established connections among carbon nanomaterial priming, mechanostimulation, and wound response, revealing recognition patterns in plant immunity. These findings promise to advance nanotechnology in sustainable agriculture by strengthening plant defenses, enhancing resilience, and reducing reliance on traditional chemicals.