Biomolecule-based piezoelectric nanostructures emerged as a new class of energy-converse materials, and designing tailored piezoelectric amino acid arrays is essential to achieve efficient electrical–mechanical coupling and fulfill their application potential. However, the controlled growth of amino acid nanostructures is still challenging due to the limited understanding of their growth mechanism. Herein, we base on the Stranski–Krastanov (S–K) growth mode and propose a mechanism for the growth of ordered amino acid array structures via physical vapor deposition. The growth of vertical valine sheet arrays is examined by changing the substrate temperature, chamber pressure, and source–substrate distance, and a “layer-plus-sheet” growth process is revealed. The modified S–K growth mode is applied to fabricate other amino acid nanostructures like leucine and isoleucine. The growth mode not only explains the formation of uniform and controllable morphology of amino acid structures but also leads to the significant enhancement of their piezoelectric properties. The maximal effective piezoelectric constant of valine sheets is 11.4 pm V–1, which approaches its highest predicted value. The output voltage of the valine array-based nanogenerator is ∼4.6 times the output voltage of the valine powder-based nanogenerator. This work provides new insights into the growth mechanism of ordered piezoelectric amino acid arrays, making them promising candidates for applications in wearable or implantable electronic devices.

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Theranostics is an emerging technique for cancer treatments due to its safety and high efficiency. However, the stability, efficiency, and convenience of preparation are the main challenges for developing theranostics. Here we describe a one-pot process for biocompatible metal–organic framework (MOF)-based theranostics. The ligand H2L designed for the MOF enables both red fluorescence emission and photodynamic therapy (PDT). The frame and regular channel structure of H2L-MOF empower the theranostics with good drug delivery performance, and the uniform and nano-sized particles facilitate the in vivo imaging/therapy applications. In vivo fluorescence imaging and in vitro chemo-photodynamic therapy were achieved with the MOF without any further modification. Our results reveal an effective strategy to achieve multifunctional theranostics by the synergistic action of the organic ligand, metal node, and channel structure of MOF nanoparticles.

Atomically thin two-dimensional (2D) CN sheets have attracted extensive attention in the field of photocatalysis because of their shorter diffusion path of photogenerated carriers and abundant surface reaction sites than bulk CN. However, 2D CNs still exhibit poor visible-light photocatalytic activity because of a strong quantum size effect. Here, PCN-222/CNs vdWHs were successfully constructed using the electrostatic self-assembly method. The results showed that PCN-222/CNs vdWHs with 1 wt.% PCN-222 enhanced the absorption range of CNs from 420 to 438 nm, which improved the absorption capacity of visible light. Additionally, the hydrogen production rate of 1 wt.% PCN-222/CNs is four times that of the pristine 2D CNs. This study provides a simple and effective strategy for 2D CN-based photocatalysts to promote visible light absorption.