Polyphenol-Derived Carbonaceous Frameworks with Multiscale Porosity for High-Power Electrochemical Applications.

With the escalating global demand for electric vehicles and sustainable energy solutions, increasing focus is placed on developing electrochemical systems that offer fast charging and high-power output, primarily governed by mass transport. Accordingly, porous carbons have emerged as highly promising electrochemically active or supporting materials due to expansive surface areas, tunable pore structures, and superior electrical conductivity, accelerating surface reaction. Yet, while substantial research has been devoted to crafting various porous carbons to increase specific surface areas, the optimal utilization of the surfaces remains underexplored. This review emphasizes the critical role of the fluid dynamics within multiscale porous carbonaceous electrodes, leading to substantially enhanced pore utilization in electrochemical systems. It elaborates on strategies of using sacrificial templates for incorporating meso/macropores into microporous carbon matrix, while exploiting the unique properties of polyphenol moieties such as sustainable carbons derived from biomass, inherent adhesive/cohesive interactions with template materials, and facile complexation capabilities with diverse materials, thereby enabling adaptive structural modulations. Furthermore, it explores how multiscale pore configurations influence pore-utilization efficiency, demonstrating advantages of incorporating multiscale pores. Finally, synergistic impact on the high-power electrochemical systems is examined, attributed to improved fluid-dynamic behavior within the carbonaceous frameworks, providing insights for advancing next-generation high-power electrochemical applications.

Metal-Phenolic Network-Coated Hyaluronic Acid Nanoparticles for pH-Responsive Drug Delivery.

Although self-assembled nanoparticles (SNPs) have been used extensively for targeted drug delivery, their clinical applications have been limited since most of the drugs are released into the blood before they reach their target site. In this study, metal-phenolic network (MPN)-coated SNPs (MPN-SNPs), which consist of an amphiphilic hyaluronic acid derivative, were prepared to be a pH-responsive nanocarrier to facilitate drug release in tumor microenvironments (TME). Due to their amphiphilic nature, SNPs were capable of encapsulating doxorubicin (DOX), chosen as the model anticancer drug. Tannic acid and FeCl3 were added to the surface of the DOX-SNPs, which allowed them to be readily coated with MPNs as the diffusion barrier. The pH-sensitive MPN corona allowed for a rapid release of DOX and effective cellular SNP uptake in the mildly acidic condition (pH 6.5) mimicking TME, to which the hyaluronic acid was exposed to facilitate receptor-mediated endocytosis. The DOX-loaded MPN-SNPs exhibited a higher cytotoxicity for the cancer cells, suggesting their potential use as a drug carrier in targeted cancer therapy.

Layer-by-layer assembled multilayers of charged polyurethane and graphene oxide platelets for flexible and stretchable gas barrier films.

With the advent of the era of consumer-oriented displays and mobile devices, the importance of barrier film coatings for securing devices from oxygen or moisture penetration has become more salient. Recently developed approaches to generate gas barrier films in a combination of polyelectrolyte multilayer matrices and incorporated inorganic nanosheets have shown great potential in outperforming conventional gas barrier films. However, these films have the intrinsic drawback of vulnerability to brittleness and inability to stretch for flexible device applications. To overcome this issue, we present a method in which we prepare multilayered films of complementarily charged polyurethane and graphene oxide platelets using spin-assisted, layer-by-layer self-assembly to obtain well-stacked film structures. As a result, the multilayered, thin films deposited on a poly(ethylene terephthalate) (PET) substrate can exhibit significantly reduced oxygen penetration properties (∼30 cc m-2 day-1 for the oxygen transmission rate) while still demonstrating large bending or stretching deformations. Therefore, the proposed approach in this study is anticipated to be extensively utilized for surface coating and protection of flexible and stretchable devices under various operating conditions.

Patterned Poly(dopamine) Films for Enhanced Cell Adhesion.

Engineered materials that promote cell adhesion and cell growth are important in tissue engineering and regenerative medicine. In this work, we produced poly(dopamine) (PDA) films with engineered patterns for improved cell adhesion. The patterned films were synthesized via the polymerization of dopamine at the air-water interface of a floating bed of spherical particles. Subsequent dissolution of the particles yielded free-standing PDA films with tunable geometrical patterns. Our results show that these patterned PDA films significantly enhance the adhesion of both cancer cells and stem cells, thus showing promise as substrates for cell attachment for various biomedical applications.

A simple one-step assay platform based on fluorescence quenching of macroporous silicon.

We synthesized 3D macroporous silicon through a simple electrochemical dissolution process and systematically estimated its protein adsorption and effect on fluorescence emission. Compared with conventional 2D polystyrene plate, the macroporous silicon showed a superior protein adsorption capacity and significant fluorescence quenching effect. We developed a 3D macroporous silicon-based adenosine assay system through the following fabrication process: streptavidin molecules that have been immobilized on the surface of macroporous silicon are attached with biotin-linked and adenosine-specific DNA aptamer, followed by hybridization between the attached aptamer and fluorescent chemical (carboxytetramethylrhodamine/CTMR) that is conjugated with a short complementary DNA sequence. In the absence of adenosine, the aptamer-CTMR complexes remain closely attached to the surface of porous silicon, hence fluorescence being significantly quenched. Upon binding to adenosine, the DNA aptamer is subject to structure switching that leads to dissociation of CTMR from DNA aptamer, and consequently the CTMR fluorescence is restored, indicating a simple one-step assay of adenosine. Compared to the conventional 2D PS and ZnO nanorods-based assays, adenosine at much lower (sub-micromolar) concentration was successfully detected through the 3D macroporous silicon-based assay. The three-dimensionally and densely immobilized aptamer probes and effective fluorescence quenching on the surface of macroporous silicon enables adenosine to be detected at lower levels. Although the adenosine detection is reported here as a proof-of-concept, the developed macroporous silicon-based simple one-step assay platform can be applied in general to fluorescence quenching -based detection of many other biomolecules.

The interplay of peptide sequence and local structure in TiO2 biomineralization.

Using cyclic constrained TiO(2) binding peptides STB1 (CHKKPSKSC), RSTB1 (CHRRPSRSC) and linear peptide LSTB1 (AHKKPSKSA), it was shown that while affinity of the peptide to TiO(2) is essential to enable TiO(2) biomineralization, other factors such as biomineralization kinetics and peptide local structure need to be considered to predict biomineralization efficacy. Cyclic and linear TiO(2) binding peptides show significantly different biomineralization activities. Cyclic STB1 and RSTB1 could induce TiO(2) precipitation in the presence of titanium(IV)-bis-ammonium-lactato-dihydroxide (TiBALDH) precursor in water or tris buffer at pH 8. In contrast, linear LSTB1 was unable to mineralize TiO(2) under the same experimental conditions despite its high affinity to TiO(2) comparable with STB1 and/or RSTB1. LSTB1 being a flexible molecule could not render the stable condensation of TiBALDH precursor to form TiO(2) particles. However, in the presence of phosphate buffer ions, the structure of LSTB1 is stabilized, leading to efficient condensation of TiBALDH and TiO(2) particle formation. This study demonstrates that peptide-mediated TiO(2) mineralization is governed by a complicated interplay of peptide sequence, local structure, kinetics and the presence of mineralizing aider such as phosphate ions.