Temperature is a fundamental parameter for all forms of lives. Natural evolution has resulted in organisms which have excellent thermoregulation capabilities in extreme climates. Bioinspired materials that mimic biological solution for thermoregulation have proven promising for passive radiative cooling. However, scalable production of artificial photonic radiators with complex structures, outstanding properties, high throughput, and low cost is still challenging. Herein, we design and demonstrate biologically inspired photonic materials for passive radiative cooling, after discovery of longicorn beetles’ excellent thermoregulatory function with their dual-scale fluffs. The natural fluffs exhibit a finely structured triangular cross-section with two thermoregulatory effects which effectively reflects sunlight and emits thermal radiation, thereby decreasing the beetles’ body temperature. Inspired by the finding, a photonic film consisting of a micropyramid-arrayed polymer matrix with random ceramic particles is fabricated with high throughput. The film reflects ∼95% of solar irradiance and exhibits an infrared emissivity >0.96. The effective cooling power is found to be ∼90.8 W⋅m−2and a temperature decrease of up to 5.1 °C is recorded under direct sunlight. Additionally, the film exhibits hydrophobicity, superior flexibility, and strong mechanical strength, which is promising for thermal management in various electronic devices and wearable products. Our work paves the way for designing and fabrication of high-performance thermal regulation materials.

In this study, large-area hexagonal-packed Si nanorod (SiNR) arrays in conjunction with Au nanoparticles (AuNPs) were fabricated for surface-enhanced Raman spectroscopy (SERS). We have achieved ultrasensitive molecular detection with high reproducibility and spatial uniformity. A finite-difference time-domain simulation suggests that a wide range of three-dimensional electric fields are generated along the surfaces of the SiNR array. With the tuning of the gap and diameter of the SiNRs, the produced long decay length (>130 nm) of the enhanced electric field makes the SERS substrate a zero-gap system for ultrasensitive detection of large biomolecules. In the detection of R6G molecules, our SERS system achieved an enhancement factor of >10 with a relative standard deviation as small as 3.9-7.2% over 30 points across the substrate. More significantly, the SERS substrate yielded ultrasensitive Raman signals on long amyloid-β fibrils at the single-fibril level, which provides promising potentials for ultrasensitive detection of amyloid aggregates that are related to Alzheimer's disease. Our study demonstrates that the SiNRs functionalized with AuNPs may serve as excellent SERS substrates in chemical and biomedical detection.

Colloidal matter with a wide range of materials, sizes, and configurations was built with opto-thermophoretic assembly.

nanostructures as building blocks. The excitation of the light-coupled collective resonances of free electrons in plasmonic nanostructures leads to the strong lightmatter interactions at the subwavelength scale. The chiral configuration makes the interactions depend on whether the incident light has left-handed circularly polarization (LCP) or right-handed circularly polarization (RCP). Therefore, it is possible to achieve plasmonic chiral metamaterials with strongly enhanced chiroptical effects and compact size. [1,[16][17][18] A large number of plasmonic chiral metamaterials with different configurations have been demonstrated including gammadions, [19] helixes, [10] and self-assembled chiral super structures. [20] The building blocks for solid-state chiral metamaterials on substrates are either inherently chiral plasmonic nanostructures [21][22][23][24] or anisotropic achiral plasmonic nanostructures stacked into chiral structures with site-specific twists. [25][26][27][28] Fabrication of these building blocks often requires sophisticated lithographic techniques such as e-beam lithography and focused ion-beam lithography to define features at the nanoscale for targeted performances. Moreover, multistep precise alignments are needed to fabricate the metamaterials consisted of the stacked building blocks. The structural and spatial precision for the building blocks is often below 50 nm for the metamaterials working in the visible and near-infrared regimes, limiting the fabrication throughput, scalability, and reproducibility. In addition, new design and fabrication of the samples are needed to tune the chiroptical responses.Herein, we report a new type of chiral metamaterials, known as moiré chiral metamaterials (MCMs), consisted of two layers of identical achiral Au nanohole arrays stacked into moiré patterns. In contrast to the previously reported plasmonic chiral metamaterials based on local structural chirality or site-specific twisting of anisotropic components, the optical chirality of MCMs is originated from relative in-plane rotation between the lattice directions of the two identical achiral layers. The chiroptical responses of the moiré chiral metamaterials can be precisely tuned by the in-plane rotation between the two layers of nanohole arrays. Through experimental and theoretical studies, we reveal mechanism behind the chiroptical effects in the moiré chiral metamaterials. Furthermore, we apply the moiré chiral metamaterials to achieve label-free enantiodiscrimination of biomolecules and drug molecules at the picogram level. With their ultrathin thickness (≈70 nm, which is only ≈1/10 of the operation wavelength), strong chirality, and high tunability, Plasmonic chiral metamaterials are promising for applications in chiral sensors and photonic devices due to their strong optical chirality and lightmatter interactions at the subwavelength scale. However, most of current plasmonic chiral metamaterials rely on local structural chirality or site-specific symmetry breaking, which has limited their optica...