Polyelectrolyte Brush-Grafted Polydopamine-Based Catalysts with Enhanced Catalytic Activity and Stability

Surface Modification of Polydopamine Particles with Polyethyleneimine Brushes for Enhanced Stability and Reduced Fragmentation

Polydopamine (Pdop) particles possess unique properties but suffer from inherent instability in aqueous environments due to the gradual release of Pdop fragments. This study demonstrated the successful enhancement of the stability and reduction in fragmentation in Pdop particles through surface engineering strategies. Specifically, we investigated the effects of polyelectrolyte multilayer (PEM) coating and polyelectrolyte (PE) brush grafting. Our results showed that PE brush grafting, particularly with long-chain polyethyleneimine (PEI), was more effective in suppressing Pdop fragment release compared to PEM coating. The L-PEI grafted Pdop particles (2.28 chains/nm2) exhibited remarkable stability across a wide pH range (3-9), with inhibition rates exceeding 90% in most cases, reaching 93% at pH 5. Furthermore, a direct correlation between PEI grafting density (0.64 to 2.28 chains/nm2) and inhibition rate was observed, with higher densities yielding greater stability. These findings offer a promising approach for stabilizing Pdop particles for diverse applications.

A Janus branch filter for washing machines: Simultaneous removal of microplastics and surfactants

Emerging pollutants, such as microplastics (MPs), are becoming a significant issue worldwide. The highest percentage of MPs released into the environment occurs through daily laundry. The average weight of dreg obtained from 5 kg of laundry was 1.26 g/kg. According to energy dispersive X-ray (EDX) and thermogravimetric analysis (TGA) analyses, the dreg consisted of MPs (78.3-89 wt%, organic elements: C/O) and alien materials (11-21.7 wt%, inorganic elements: Al/Fe/Ca, etc.). Thus, to reproduce the real environment, alien materials (Fe₃O₄ and CaCO₃) were added to various types of model MPs in the presence and absence of sodium dodecyl benzenesulfonate (SDBS) to test MP removal. Hydrophobic and hydrophilic MPs were generated upon laundering, accounting for 55-59% and 41-45% of MPs, respectively. We provide a novel approach to design a laundry filter system for the simultaneous removal of SDBS and hydrophilic/hydrophobic MPs.

Laminar flow-assisted synthesis of amorphous ZIF-8-based nano-motor with enhanced transmigration for photothermal cancer therapy

Because of their biocompatibility, there are promising applications in various fields for enzyme-powered nano-motors. However, enzymes can undergo denaturation under harsh conditions. Here, we report the flow-assisted synthesis of an enzyme-based amorphous ZIF-8 nano-motor (A-motor; Pdop@urease@aZIF-8) for enhanced movement and protection of polydopamine and enzymes. Multiple laminar flow types with varied input ratios effectively entrapped enzymes into amorphous ZIF-8 shells in a serial flow with a momentary difference. The obtained A-motor exhibited superior enzymatic activity and photothermal ablation properties with excellent durability due to the protection the amorphous shell offers from the external environment. Furthermore, in the bio-mimic 2D membrane model, the enhanced mobility of the A-motor afforded high transmigration (>80%), which had a powerful effect on bladder cancer cell ablation via photothermal therapy. This work envisages that the rapid flow approach will facilitate scalable manufacturing of the nano-motors under low stress to vulnerable biomolecules, which would be extended to nano-biomedical applications in various body environments.

Polyethyleneimine-assisted co-deposition of polydopamine coating with enhanced stability and efficient secondary modification

The stability and grafting efficiency are important for polydopamine (pDA) coatings used as platforms for secondary grafting.

New insight into the bioinspired sub-10 nm Sn(HPO4)2 confinement for efficient heavy metal remediation in wastewater

Heavy metal pollution poses a severe threat to the water environment. Engineering sub-10 nm active functional materials is an important approach to address the problems, and nanocomposites, developed in recent years by pore confinement always present weaken diffusion and low utilization of nanoparticles. In this study, we successfully prepared the polydopamine confined high-density sub-10 nm Sn(HPO₄)₂ coating for toxic lead(II) removal and its unique external coating structure and superior active sub-10 nm size achieved remarkable performances for heavy metal remediation. The hybrid sub-10 nm coating exhibits an extended acidic environment application (pH = 2.0-7.0) as well as significant selectivity with a superior K_d values (9.4 × 10⁴ mL/g, which is 450 times greater than that of commercial sulfonated polystyrene. Ultrafast filtrations by vacuum further validate its superior sequestration (near to 100%) to Pb and Cd ions at different concentrations (10-100 mg/L) for 2 mins. The real column application further demonstrates the remarkable capacity of 11800 kg/kg sorbents, the trace effluents with three orders (∼10³) reduction to below 1 ppb (> 99.9% Pb removal) and efficient stability for several cycles. The effective performances are mainly driven by the PDA motivated external nanoparticles arrangement and strong inner-sphere complexation by small size of Sn(HPO₄)₂. These results set a new benchmark for removing toxic metals and the proposed approach (engineering sub-10 nm coating design) is unique for heavy metal removal.

Metal-Containing Polydopamine Nanomaterials: Catalysis, Energy, and Theranostics

Polydopamine (PDA) is a major type of artificial melanin material with many interesting properties such as antioxidant activity, free-radical scavenging, high photothermal conversion efficiency, and strong metal-ion chelation. The high affinity of PDA to a wide range of metals/metal ions has offered a new class of functional metal-containing polydopamine (MPDA) nanomaterials with promising functions and extensive applications. Understanding and controlling the metal coordination environment is vital to achieve desirable functions for which such materials can be exploited. MPDA nanomaterials with metal/metal ions as the active functions are reviewed, including their synthesis and metal coordination environment and their applications in catalysis, batteries, solar cells, capacitors, medical imaging, cancer therapy, antifouling, and antibacterial coating. The current trends, limitations, and future directions of this area are also explored.

An Active Absorbent for Cleanup of High-Concentration Strong Acid and Base Solutions

There is significant interest in developing novel absorbents for hazardous material cleanup. Iron oxide-coated melamine formaldehyde sponge (MFS/IO) absorbents with various IO layer thicknesses were synthesized. Various other absorbents were also synthesized and compared to evaluate the absorption capability of the MFS/IO absorbents for strong acid (15%, v/v) and base (50%, m/m) solutions. Specifically, absorbent and solution drop tests, dust tests, and droplet fragment tests were performed. Among the various absorbents, MFS/IO absorbents possessing a needlelike surface morphology showed several unique characteristics not observed in other absorbents. The MFS/IO absorbents naturally absorbed a strong base solution (absorption time: 0.71–0.5 s, absorption capacity: 10,000–34,000%) without an additional external force and immediately absorbed a strong acid solution (0.31–0.43 s, 9830–10,810%) without absorption delay/overflow during absorbent and solution drop tests, respectively. The MFS/IO absorbents were also demonstrated to be ideal absorbents that generated fewer dust particles (semiclass 1 (ISO 3) level of 280 piece/L) than the level of a clean room (class 100). Furthermore, the MFS/IO absorbents were able to prevent the formation of droplet fragments and solution overflow during the solution drop test due to their unique surface morphology and extremely high absorption speed/capacity, respectively.