Effect of the Host Lattice Environment on the Expression of 5s2 Lone-Pair Electrons in a 0D Bismuth-Based Metal Halide.

ns2-Metal halide perovskites have attracted wide attention due to their fascinating photophysical properties. However, achieving high photoluminescence (PL) properties is still an enormous challenge, and the relationship between the lattice environment and ns2-electron expression is still elusive. Herein, an organic-inorganic Bi3+-based halide (C5H14N2)2BiCl6·Cl·2H2O (C5H14N22+ = doubly protonated 1-methylpiperazine) with a six-coordinated structure has been successfully prepared, which, however, exhibits inferior PL properties due to the chemically inert expression of Bi3+-6s2 lone-pair electrons. After reasonably embedding Sb3+ with 5s2 electrons into the lattice of (C5H14N2)2BiCl6·Cl·2H2O, the host lattice environment induces the Sb-Cl moiety to change from the original five-coordinated to six-coordinated structure, thereby resulting in a broad-band yellow emission with a PL efficiency up to 50.75%. By utilizing the host lattice of (C5H14N2)2BiCl6·Cl·2H2O, the expression of Sb3+-5s2 lone-pair electrons is improved and thus promotes the radiative recombination from the Sb3+-3P1 state, resulting in the enhanced PL efficiency. This work will provide an in-depth insight into the effect of the local structure on the expression of Sb3+-5s2 lone-pair electrons.

Surface engineering of titanium implants with enzyme-triggered antibacterial properties and enhanced osseointegration in vivo.

Preventing bacterial infection and improving the osseointegration of titanium (Ti) and its alloys are both highly crucial factors for their long-term successful implantation in clinical applications. However, the straightforward applications of antibacterial surfaces on Ti-based materials remain limited due to their side effects on cytocompatibility. Herein, catechol-functionalized multilayer films composed of dopamine-modified hyaluronic acid (HA-c) and 3,4-dihydroxyhydrocinnamic acid-modified chitosan (Chi-c) were developed on Ti substrates modified with TiO2 nanotube arrays loaded with an antibacterial drug. The treated Ti substrate showed strong hydrophilicity, with a water contact angle of about 20°, and obviously inhibited early-stage bacterial adhesion. Moreover, this system displayed an enzyme-responsive release of antibacterial drug triggered by the hyaluronidase degradation of HA-c, which exhibited effective antibacterial ability and eliminated side effects caused by burst release of antibiotics. Meanwhile, the modified Ti substrates significantly promoted initial osteoblast adhesion through up-regulating the expression of adhesion-related genes, including integrin αv and ß3. More importantly, this prepared coating with bacterial self-responsiveness improved osseointegration and prevented bacterial infection of Ti implants in vivo. Overall, our developed catechol-functionalized and bacterial self-responsive coating on Ti substrate has great significance in clinical applications of orthopedic and dental implants.