Engineering Biomolecular Self-Assembly at Solid-Liquid Interfaces

Biomolecular self-assembly is a key process used by life to build functional materials from the "bottom up." In the last few decades, bioengineering and bionanotechnology have borrowed this strategy to design and synthesize numerous biomolecular and hybrid materials with diverse architectures and properties. However, engineering biomolecular self-assembly at solid-liquid interfaces into predesigned architectures lags the progress made in bulk solution both in practice and theory. Here, recent achievements in programming self-assembly of peptides, proteins, and peptoids at solid-liquid interfaces are summarized and corresponding applications are described. Recent advances in the physical understandings of self-assembly pathways obtained using in situ atomic force microscopy are also discussed. These advances will lead to novel strategies for designing biomaterials organized at and interfaced with inorganic surfaces.

Cocatalyzing Pt/PtO Phase-Junction Nanodots on Hierarchically Porous TiO2 for Highly Enhanced Photocatalytic Hydrogen Production

Phase-junctions between a cocatalyst and its semiconductor host are quite effective to enhance the photocatalytic activity and are widely studied, while reports on the phase-juncted cocatalyst are still rare. In this work, we report the deposition of the Pt/PtO phase-juncted nanodots as cocatalyst via NaOH modification of an interconnected meso-macroporous TiO₂ network with high surface area and inner-particle mesopores to enhance the performance of photocatalytic H₂ production. Our results show that NaOH modification can largely influence Pt/PtO phase-juncted nanodot formation and dispersity. Compared to the TiO₂ nanoparticles, the hierarchically meso-macroporous TiO₂ network containing 0.18 wt % Pt/PtO phase-juncted cocatalyst demonstrates a highest photocatalytic H₂ rate of 13 mmol g^-1 h^-1 under simulated solar light, and possesses a stable cycling activity without obvious decrease after five cycles. Such high H₂ production performance can be attributed to both the phase-juncted Pt/PtO providing more active sites while PtO suppresses the undesirable hydrogen back reaction, and the special hierarchically porous TiO₂ network with inner-particle mesopores presenting short diffusion path lengths for photogenerated electrons and enhanced light harvesting efficiency. This work suggests that Pt/PtO phase-juncted cocatalyst on hierarchically porous TiO₂ nanostructures is a promising strategy for advanced photocatalytic H₂ production.

Long-Range Architecture of Single Lipid-Based Complex Nanoparticles with Local Hexagonal Packing

The three-dimensional architecture of single nanoparticles made of inverse micellar lipids templated on polyelectrolytes and exhibiting a local hexagonal packing is elucidated by high-resolution cryoelectron microscopy and coarse-grained Monte Carlo simulations. Cryoelectron microscopy demonstrates that the internal structure of the complexes is less ordered than commonly recognized from X-ray diffraction. We have devised a coarse-grained model of self-avoiding flexible tubes mimicking the lipid-coated polyelectrolytes and interacting via a short-range attractive potential. Consistently with cryoelectron microscopy, the resulting clusters obtained through a Monte Carlo scheme exhibit a varying degree of order ranging from weakly organized aggregates to partially organized spooled and straight bundles, depending on the length and on the persistence length of the tubes. These findings may help in the design of self-assembled lipid-based complexes for biomedical and nanotechnological applications.

Adhesion-Assisted Antioxidant-Engineered Mesenchymal Stromal Cells for Enhanced Cardiac Repair in Myocardial Infarction

Mesenchymal stromal cell (MSC) therapy holds great promise for treating myocardial infarction (MI). However, the inflammatory and reactive oxygen species (ROS)-rich environment in infarcted myocardium challenges MSC survival, limiting its therapeutic impact. In this study, we demonstrate that chemical modification of MSCs with anti-VCAM1 and polydopamine (PD) significantly enhances MSC survival and promotes cardiac repair. Anti-VCAM1 modification facilitates MSC adhesion to inflamed tissue, ensuring MSC retention in the injured myocardium, while PD scavenges ROS surrounding MSCs, creating a conducive environment for cell transplantation. Our data indicate that chemically engineered MSCs effectively disrupt the inflammation-ROS cycle and modulate inflammation-related immune responses, thus improving MI microenvironments. Single-cell RNA sequencing of rat hearts reveals that treatment with engineered MSCs inhibits cardiac fibrosis by suppressing HB-EGF-EGFR signaling between anti-inflammatory macrophages and activated fibrillates. Ultimately, engineered MSCs demonstrate superior therapeutic efficacy in a rat model of MI. This study presents a straightforward, safe, and efficient chemical method for enhancing MSC therapy.