Bioinspired Mineral–Organic Bone Adhesives for Stable Fracture Fixation and Accelerated Bone Regeneration

The use of hydrogel‐based bone adhesives has the potential to revolutionize the clinical treatment of bone repairs. However, severe deficiencies remain in current products, including cytotoxicity concerns, inappropriate mechanical strength, and poor fixation performance in wet biological environments. Inspired by the unique roles of glue molecules in the robust mechanical strength and fracture resistance of bone, a design strategy is proposed using novel mineral–organic bone adhesives for strong water‐resistant fixation and guided bone tissue regeneration. The system leveraged tannic acid (TA) as a phenolic glue molecule to spontaneously co‐assemble with silk fibroin (SF) and hydroxyapatite (HA) in order to fabricate the inorganic–organic hybrid hydrogel (named SF@TA@HA). The combination of the strong affinity between SF and TA along with sacrificial coordination bonds between TA and HA significantly improves the toughness and adhesion strength of the hydrogel by increasing the amount of energy dissipation at the nanoscale. This in turn facilitated adequate and stable fixation of bone fracture in wet biological environments. Furthermore, SF@TA@HA promotes the regeneration of bone defects at an early stage in vivo. This work presents a type of bioinspired bone adhesive that is able to provide stable fracture fixation and accelerated bone regeneration during the bone remodeling process.     

Production and Potential of Bioactive Glass Nanofibers as a Next‐Generation Biomaterial

Over the past decades, bioactive glass has played a central role in the bone regeneration field, due to its excellent bioactivity, osteoconductivity, and even osteoinductivity. Herein, exploitation of bioactive glass as a one‐dimensional nanoscale fiber by employing an electrospinning process based on a sol–gel precursor is reported for the first time. Under controlled processing conditions, continuous nanofibers have been generated successfully with variable diameters. The excellent bioactivity of the nanofiber is confirmed in vitro within a simulated body fluid by the rapid induction of bonelike minerals onto the nanofiber surface. The bone‐marrow‐derived cells are observed to attach and proliferate actively on the nanofiber mesh, and differentiate into osteoblastic cells with excellent osteogenic potential. The bioactive nanofibers have been further exploited in various forms, such as bundled filament, nanofibrous membrane, 3D macroporous scaffold, and nanocomposite with biopolymer, suggesting their versatility and potential applications in bone‐tissue engineering. Based on this study, the bioactive nanofibrous matrix is regarded as a promising next‐generation biomaterial in the bone‐regeneration field.     

Biomimetic Elastomeric Bioactive Siloxane‐Based Hybrid Nanofibrous Scaffolds with miRNA Activation: A Joint Physico‐Chemical‐Biological Strategy for Promoting Bone Regeneration

Rapid and efficient disease‐induced or critical‐size bone regeneration remains a challenge in tissue engineering due to the lack of highly bioactive biomaterial scaffolds. Physical structures such as nanostructures, chemical components such as silicon elements, and biological factors such as genes have shown positive effects on bone regeneration. Herein, a bioactive photoluminescent elastomeric silicate‐based nanofibrous scaffold with sustained miRNA release is reported for promoting bone regeneration based on a joint physico‐chemical‐biological strategy. Bioactive nanofibrous scaffolds are fabricated by cospinning poly (ε‐caprolactone) (PCL), elastomeric poly (citrates‐siloxane) (PCS), and bioactive osteogenic miRNA nanocomplexes (denoted PPM nanofibrous scaffolds). The PPM scaffolds possess uniform nanostructures, significantly enhanced tensile stress (≈15 MPa) and modulus (≈32 MPa), improved hydrophilicity (30–60°), controlled biodegradation, and strong blue fluorescence. Bioactive miRNA complexes are efficiently loaded into the nanofibrous matrix and exhibit long‐term release for up to 70 h. The PPM scaffolds significantly promote the adhesion, proliferation, and osteoblast differentiation of bone marrow stem cells in vitro and enhanced rat cranial defect restoration (12 weeks) in vivo. This work reports an attractive joint physico‐chemical‐biological strategy for the design of novel cell/protein‐free bioactive scaffolds for synergistic tissue regeneration.     

Development of a Multifunctional Platform Based on Strong,Intrinsically Photoluminescent and Antimicrobial Silica‐Poly(citrates)‐Based Hybrid Biodegradable Elastomers for Bone Regeneration

Biodegradable biomaterials with intrinsically multifunctional properties such as high strength, photoluminescent ability (bioimaging monitoring), and antimicrobial activity (anti‐infection), as well as high osteoblastic differentiation ability, play a critical role in successful bone tissue regeneration. However, fabricating a biomaterial containing all these functions is still a challenge. Here, urethane cross‐linked intrinsically multifunctional silica‐poly(citrate) (CMSPC)‐based hybrid elastomers are developed by first one‐step polymerization and further chemical crosslinked using isocyanate. CMSPC hybrid elastomers demonstrate a high modulus of 976 ± 15 MPa, which is superior compared with most conventional poly(citrate)‐based elastomers. Hybrid elastomers show strong and stable intrinsic photoluminescent ability (emission 400–600 nm) due to the incorporation of silica phase. All elastomers exhibit high inherent antibacterial properties against Staphylococcus aureus. In addition, CMSPC hybrid elastomers significantly enhance the proliferation and metabolic activity of osteoblasts (MC3T3‐E1). CMSPC hybrid elastomers significantly promote the osteogenic differentiation of MC3T3‐E1 by improving alkaline phosphatase activity and calcium biomineralization deposits, as well as expressions of osteoblastic genes. These hybrid elastomers also show a minimal inflammatory response indicated by subcutaneous transplantation in vivo. These optimized structure and multifunctional properties make this hybrid elastomer highly promising for bone tissue regeneration and antiinfection and bioimaging applications.     

Enhanced Physiochemical and Mechanical Performance of Chitosan‐Grafted Graphene Oxide for Superior Osteoinductivity

The regeneration of artificial bone substitutes is a potential strategy for repairing bone defects. However, the development of substitutes with appropriate osteoinductivity and physiochemical properties, such as water uptake and retention, mechanical properties, and biodegradation, remains challenging. Therefore, there is a motivation to develop new synthetic grafts that possess good biocompatibility, physiochemical properties, and osteoinductivity. Here, we fabricate a biocompatible scaffold through the covalent crosslinking of graphene oxide (GO) and carboxymethyl chitosan (CMC). The resulting GO‐CMC scaffold shows significant high water retention (44% water loss) compared with unmodified CMC scaffolds (120% water loss) due to a steric hindrance effect. The modulus and hardness of the GO‐CMC scaffold are 2.75‐ and 3.51‐fold higher, respectively, than those of the CMC scaffold. Furthermore, the osteoinductivity of the GO‐CMC scaffold is enhanced due to the π–π stacking interactions of the GO sheets, which result in striking upregulation of osteogenesis‐related genes, including osteopontin, bone sialoprotein, osterix, osteocalcin, and alkaline phosphatase. Finally, the GO‐CMC scaffold exhibits excellent reparative effects in repairing rat calvarial defects via the synergistic effects of GO and bone morphogenetic protein‐2. This study provides new insights for developing bone substitutes for tissue engineering and regenerative medicine.     

Bioprocess‐Inspired Microscale Additive Manufacturing of Multilayered TiO2/Polymer Composites with Enamel‐Like Structures and High Mechanical Properties

Natural structure‐forming processes found in biological systems are fantastic and perform at ambient temperatures, in contrast with anthropogenic technologies that commonly require harsh conditions. A new research direction “bioprocess‐inspired fabrication” is proposed to develop novel fabrication techniques for advanced materials. Enamel, an organic–inorganic composite biomaterial with outstanding mechanical performance and durability, is formed by repeating the basic blocks consisting of columnar hydroxyapatite or fluorapatite and an organic matrix. Inspired by the enamel formation process, a microscale additive manufacturing method is proposed for achieving a multilayered organic–inorganic columnar structure. In this approach, rutile titanium dioxide (TiO₂) nanorods, polymers, and graphene oxide (GO) are sequentially assembled in a layer‐by‐layer fashion to form an organic–inorganic structure. In particular, GO serves as a substrate for TiO₂ nanorods and interacts with polymers, jointly leading to the strength of the composites. Impressively, this enamel‐like structure material has hardness (1.56 ± 0.05 GPa) and ultrahigh Young's modulus (81.0 ± 2.7 GPa) comparable to natural enamel, and viscoelastic property (0.76 ± 0.12 GPa) superior to most solid materials. Consequently, this biomimetic synthetic approach provides an in‐depth understanding for the formation process of biomaterials and also enables the exploration of a new avenue for the preparation of organic–inorganic composite materials.     

Biomimetic Ultralight,Highly Porous,Shape‐Adjustable,and Biocompatible 3D Graphene Minerals via Incorporation of Self‐Assembled Peptide Nanosheets

Hybrid nanomaterials with tailored functions, consisting of self‐assembled peptides, are intensively applied in nanotechnology, tissue engineering, and biomedical applications due to their unique structures and properties. Herein, a peptide‐mediated biomimetic strategy is adopted to create the multifunctional 3D graphene foam (GF)‐based hybrid minerals. First, 2D peptide nanosheets (PNSs), obtained by self‐assembling a motif‐specific peptide molecule (LLVFGAKMLPHHGA), are expected to exhibit biofunctionality, such as the biomimetic mineralization of hydroxyapatite (HA) minerals. Subsequently, the noncovalent conjugation of PNSs onto GF support is utilized to form 3D GF‐PNSs hybrid scaffolds, which are suitable for the growth of HA minerals. The fabricated biomimetic 3D GF‐PNSs‐HA minerals exhibit adjustable shape, superlow weight (0.017 g cm^?3), high porosity (5.17 m² g^?1), and excellent biocompatibility, proving potential applications in both bone tissue engineering and biomedical engineering. To the best of the authors' knowledge, it is the first time to combine 2D PNSs and GF to fabricate 3D organic–inorganic hybrid scaffold. Further development of these hybrid GF‐PNSs scaffolds can potentially lead to materials used as matrices for drug delivery or bone tissue engineering as proven via successful 3D scaffold formation exhibiting interconnected pore‐size structures suitable for vascularization and medium transport.     

Biomimetic Mineralized Organic–Inorganic Hybrid Macrofiber with Spider Silk‐Like Supertoughness

Spider silk fibers (SSF) have a hierarchical structure composed of proteins with highly repetitive sequences and biomineralization is sophisticated in hierarchical organic–inorganic constructions. By using inorganic hydroxyapatite (HAP) and organic polyvinyl alcohol (PVA) to simulate the rigid crystalline and flexible amorphous protein blocks of SSF, respectively, biomimetic mineralization is herein attempted for the large‐scale preparation of SSF‐like macrofibers with a hierarchical ordered structure, a superhigh tensile strength of 949 ± 38 MPa, a specific toughness of 296 ± 12 J g^?1, and a stretch ability of 80.6%. The hybrid macrofibers consist of microfibers, and their outstanding performance (e.g., extreme tolerance to temperatures ranging from ?196 to 80 °C and superior ability to inhibit the transverse growth of cracks) is attributed to the hierarchical arrangement as well as the organic–inorganic integrated structure within the oriented mineralized polymer chains. The biomineralization‐inspired technique provides a promising tactic that can be used to synthesize functional organic–inorganic fibers that are structurally complex and, furthermore, industrially manufacture SSF‐like artificial fibers with a supertoughness.     

Molecular‐Level Switching of Polymer/Nanocrystal Non‐Covalent Interactions and Application in Hybrid Solar Cells

Hybrid composites obtained upon blending conjugated polymers and colloidal semiconductor nanocrystals are regarded as attractive photo­active materials for optoelectronic applications. Here it is demonstrated that tailoring nanocrystal surface chemistry permits to control non‐covalent and electronic interactions between organic and inorganic components. The pending moieties of organic ligands at the nanocrystal surface are shown to not merely confer colloidal stability while hindering charge separation and transport, but drastically impact morphology of hybrid composites during formation from blend solutions. The relevance of this approach to photovoltaic applications is demonstrated for composites based on poly(3‐hexylthiophene) and lead sulfide nanocrystals, considered as inadequate until this report, which enable the fabrication of hybrid solar cells displaying a power conversion efficiency that reaches 3%. By investigating (quasi)steady‐state and time‐resolved photo‐induced processes in the nanocomposites and their constituents, it is ascertained that electron transfer occurs at the hybrid interface yielding long‐lived separated charge carriers, whereas interfacial hole transfer appears hindered. Here a reliable alternative aiming to gain control over macroscopic optoelectronic properties of polymer/nanocrystal composites by mediating their non‐covalent interactions via ligands' pending moieties is provided, thus opening new possibilities towards efficient solution‐processed hybrid solar cells.     

Solid Free‐Form Fabrication of Tissue‐Engineering Scaffolds with a Poly(lactic‐co‐glycolic acid) Grafted Hyaluronic Acid Conjugate Encapsulating an Intact Bone Morphogenetic Protein–2/Poly(ethylene glycol) Complex

Despite wide applications of bone morphogenetic protein–2 (BMP‐2), there are few methods to incorporate BPM‐2 within polymeric scaffolds while maintaining biological activity. Solid free‐form fabrication (SFF) of tissue‐engineering scaffold is successfully carried out with poly(lactic‐co‐glycolic acid) grafted hyaluronic acid (HA‐PLGA) encapsulating intact BMP‐2/poly(ethylene glycol) (PEG) complex. HA‐PLGA conjugate is synthesized in dimethyl sulfoxide (DMSO) by the conjugation reaction of adipic acid dihydrazide modified HA (HA‐ADH) and PLGA activated with N,N′‐dicyclohexylcarbodiimide (DCC) and N‐hydroxysuccinimide (NHS). BMP‐2 is complexed with PEG, which is encapsulated within the PLGA domain of the HA‐PLGA conjugate by SFF to prepare tissue‐engineering scaffolds. In vitro release tests confirm the sustained release of intact BMP‐2 from the scaffolds for up to a month. After confirmation of the enhanced osteoblast cell growth, and high gene‐expression levels of alkaline phosphatase (ALP), osteocalcin (OC), and osterix (OSX) in the cells, the HA‐PLGA/PEG/BMP‐2 scaffolds are implanted into calvarial bone defects of Sprague Dawley (SD) rats. Microcomputed tomography (μCT) and histological analyses with Masson's trichrome, and hematoxylin and eosin (H&E) staining reveal effective bone regeneration on the scaffolds of HA‐PLGA/PEG/BMP‐2 blends.     

Hybrid Materials from Ultrahigh‐Inorganic‐Content Mineral Plastic Hydrogels: Arbitrarily Shapeable,Strong, and Tough

Natural mineralized structural materials such as nacre and bone possess a unique hierarchical structure comprising both hard and soft phases, which can achieve the perfect balance between mechanical strength and shape controllability. Nevertheless, it remains a great challenge to control the complex and predesigned shapes of artificial organic–inorganic hybrid materials at ambient conditions. Inspired by the plasticity of polymer‐induced liquid precursor phases that can penetrate and solidify in porous organic frameworks for biomineral formation, here a mineral plastic hydrogel is shown with ultrahigh silica content (≈95 wt%) that can be similarly hybridized into a porous delignified wood scaffold, and the resultant composite hydrogels can be manually made into arbitrary shapes. Subsequent air drying well preserves the designed shapes and produces fire‐retardant, ultrastrong, and tough structural organic–inorganic hybrids. The proposed mineral plastic hydrogel strategy opens an easy and eco‐friendly way for fabricating bioinspired structural materials that compromise both precise shape control and high mechanical strength.     

Highly Improved Sb2S3 Sensitized‐Inorganic–Organic Heterojunction Solar Cells and Quantification of Traps by Deep‐Level Transient Spectroscopy

The light‐harvesting Sb₂S₃ surface on mesoporous‐TiO₂ in inorganic–organic heterojunction solar cells is sulfurized with thioacetamide (TA). The photovoltaic performances are compared before and after TA treatment, and the state of the Sb₂S₃ is investigated by X‐ray diffraction, X‐ray photoelectron spectroscopy, and deep‐level transient spectroscopy (DLTS). Although there are no differences in crystallinity and composition, the TA‐treated solar cells exhibit significantly enhanced performance compared to pristine Sb₂S₃‐sensitized solar cells. From DLTS analysis, the performance enhancement is mainly attributed to the extinction of trap sites, which are present at a density of (2–5) × 10¹⁴ cm^?3 in Sb₂S₃, by TA treatment. Through such a simple treatment, the cell records an overall power conversion efficiency (PCE) of 7.5% through a metal mask under simulated illumination (AM 1.5G, 100 mW cm^–2) with a very high open circuit voltage of 711.0 mV. This PCE is, thus far, the highest reported for fully solid‐state chalcogenide‐sensitized solar cells.     

Facile Stem Cell Delivery to Bone Grafts Enabled by Smart Shape Recovery and Stiffening of Degradable Synthetic Periosteal Membranes

Delivering stem/progenitor cells via a degradable synthetic membrane to devitalized allogenic tissue graft surfaces presents a promising allograft‐mediated tissue regeneration strategy. However, balancing degradability and bioactivity of the synthetic membrane with physical characteristics demanded for successful clinical translation is challenging. Here, well‐integrated composites of hydroxyapatite (HA) and amphiphilic poly(lactide‐co‐glycolide)‐b‐poly(ethylene glycol)‐b‐poly(lactide‐co‐glycolide) (PELGA) with tunable degradation rates are designed that stiffen upon hydration and exhibit excellent shape recovery ability at body temperature for efficiently delivering skeletal progenitor cells around bone grafts. Unlike conventional degradable polymers that weaken upon wetting, these amphiphilic composites stiffen upon hydration as a result of enhanced polyethylene glycol (PEG) crystallization. HA‐PELGA composite membranes support the attachment, proliferation, and osteogenesis of rat periosteum‐derived cells in vitro, as well as the facile transfer of confluent cell sheets of green fluorescent protein‐labeled bone marrow stromal cells. With efficient shape memory behaviors around physiological temperature, the composite membranes can be programmed with a permanent tubular configuration, deformed into a flat temporary shape desired for cell seeding/cell sheet transfer, and triggered to wrap around a femoral bone allograft upon 37 °C saline rinse and subsequently stiffen. These properties combined make electrospun HA‐PELGA promising smart synthetic periosteal membranes for augmenting allograft healing.     

Growth‐Factor Free Multicomponent Nanocomposite Hydrogels That Stimulate Bone Formation

Synthetic osteo‐promoting materials that are able to stimulate and accelerate bone formation without the addition of exogenous cells or growth factors represent a major opportunity for an aging world population. A co‐assembling system that integrates hyaluronic acid tyramine ( HA‐Tyr ), bioactive peptide amphiphiles ( GHK‐Cu²⁺ ), and Laponite ( Lap ) to engineer hydrogels with physical, mechanical, and biomolecular signals that can be tuned to enhance bone regeneration is reported. The central design element of the multicomponent hydrogels is the integration of self‐assembly and enzyme‐mediated oxidative coupling to optimize structure and mechanical properties in combination with the incorporation of an osteo‐ and angio‐promoting segments to facilitate signaling. Spectroscopic techniques are used to confirm the interplay of orthogonal covalent and supramolecular interactions in multicomponent hydrogel formation. Furthermore, physico‐mechanical characterizations reveal that the multicomponent hydrogels exhibit improved compressive strength, stress relaxation profile, low swelling ratio, and retarded enzymatic degradation compared to the single component hydrogels. Applicability is validated in vitro using human mesenchymal stem cells and human umbilical vein endothelial cells, and in vivo using a rabbit maxillary sinus floor reconstruction model. Animals treated with the HA‐Tyr‐HA‐Tyr‐GHK‐Cu²⁺ hydrogels exhibit significantly enhanced bone formation relative to controls including the commercially available Bio‐Oss.     

Development of Citrate‐Based Dual‐Imaging Enabled Biodegradable Electroactive Polymers

Increasing occurrences of degenerative diseases, defective tissues, and severe cancers heighten the importance of advanced biomedical treatments, which in turn enhance the need for improved biomaterials with versatile theranostic functionalities yet using minimal design complexity. Leveraging the advantages of citrate chemistry, a multifunctional citrate‐based biomaterial platform is developed with both imaging and therapeutic capabilities utilizing a facile and efficient one‐pot synthesis. The resulting aniline tetramer doped biodegradable photoluminescent polymers (BPLPATs) not only possess programmable degradation profiles (<1 to > 6 months) and mechanical strengths (≈20 MPa to >400 MPa), but also present a combination of intrinsic fluorescence, photoacoustic (PA), and electrical conductivity properties. BPLPAT nanoparticles are able to label cells for fluorescence imaging and perform deep tissue detection with PA imaging. Coupled with significant photothermal performance, BPLPAT nanoparticles demonstrate great potential for thermal treatment and in vivo real‐time detection of cancers. The results on BPLPAT scaffolds demonstrate 3D high‐spatial‐resolution deep tissue PA imaging (23 mm), as well as promote growth and differentiation of PC‐12 nerve cells. It is envisioned that the biodegradable dual‐imaging‐enabled electroactive citrate‐based biomaterial platform will expand the currently available theranostic material systems and open new avenues for diversified biomedical and biological applications via the demonstrated multifunctionality.     

Phase‐Transited Lysozyme as a Universal Route to Bioactive Hydroxyapatite Crystalline Film

A key factor for successful design of bioactive complex, organic–inorganic hybrid biomaterials is the facilitation and control of adhesion at interfaces, as many current synthetic biomaterials are inert, lacking interfacial bioactivity. In this regard, the development of a simple, unified way to biofunctionalize diverse organic and inorganic materials toward biomineralization remains a critical challenge. In this report, a universal biomimetic mineralization route that can be applied to virtually any type and morphology of scaffold materials is provided to induce nucleation and growth of hydroxyapatite (HAp) crystals based on phase‐transited lysozyme (PTL) coating. Surface‐anchored abundant functional groups in the PTL enrich the interface with strongly bonded calcium ions, facilitating the formation of HAp crystals in simulated body fluid with the morphology and alignment being similar to that observed in natural HAp in mineralized tissues. By the adhesion of amyloid contained in the PTL, such protein assembly could readily integrate HAp on ceramics, metals, semiconductors, and synthetic polymers irrespective of their size and morphology, with robust bonding stability and corresponding ultralow wear extent under normal bone pressure. This strategy successfully improves the in vivo osteoconductivity of Ti‐based implant, underpinning the expectation for such biomaterial in future biointerface and tissue engineering.     

Room‐Temperature Self‐Healing and Recyclable Tough Polymer Composites Using Nitrogen‐Coordinated Boroxines

In this paper, nitrogen‐coordinated boroxines are exploited for the fabrication of self‐healing and recyclable polymer composites with enhanced mechanical properties. The 3D polymer networks cross‐linked with nitrogen‐coordinated boroxines are first synthesized through the trimerization of ortho‐aminomethyl‐phenylboronic acid groups at the terminals of poly(propylene glycol) (PPG) chains, and subsequently, the mechanically robust polymer composites are fabricated by utilizing the complexation of nitrogen‐coordinated boroxine‐containing PPG (N‐boroxine‐PPG) with poly(acrylic acid) (PAA) and hydrogen‐bonding interactions between them. The N‐boroxine‐PPG is soft with a tensile strength of 0.19 MPa, whereas the tensile strengths of N‐boroxine‐PPG/PAA composites can be tailored to range from 1.7 to 12.7 MPa by increasing the PAA contents in the polymer composites. It is revealed that the amine ligands can facilitate the formation and dissociation of nitrogen‐coordinated boroxines at room temperature. Moreover, the reversibility of nitrogen‐coordinated boroxines and hydrogen‐bonding interactions enable multiple cycles of healing and recycling of the damaged N‐boroxine‐PPG/PAA composites. The healed and recycled N‐boroxine‐PPG/PAA polymer composites regain most of their mechanical strength.     

Nanofiber Generation of Gelatin–Hydroxyapatite Biomimetics for Guided Tissue Regeneration

The development of biomimetic bone matrices is one of the major goals in the bone‐regeneration and tissue‐engineering fields. Nanocomposites consisting of a natural polymer and hydroxyapatite (HA) nanocrystals, which mimic the human bone matrix, are thus regarded as promising bone regenerative materials. Herein, we developed a biomimetic nanocomposite with a novel nanofibrous structure by employing an electrospinning (ES) method. The HA precipitate/gelatin matrix nanocomposites are lyophilized and dissolved in an organic solvent, and then electrospun under controlled conditions. With this process, we can successfully generate a continuous fiber with a diameter of the order of hundreds of nanometers. The internal structure of the nanofiber features a typical nanocomposite, i.e., HA nanocrystals well distributed within a gelatin matrix. These nanocomposite fibers improve the bone‐derived cellular activity significantly when compared to the pure gelatin equivalent. This method of generating a nanofiber of the biomimetic nanocomposite was effective in producing a biomedical membrane with a composition gradient, which is potentially applicable in the field of guided tissue regeneration (GTR).     

Large‐Scale Fabrication of Three‐Dimensional Surface Patterns Using Template‐Defined Electrochemical Deposition

A new strategy to achieve large‐scale, three‐dimensional (3D) micro‐ and nanostructured surface patterns through selective electrochemical growth on monolayer colloidal crystal (MCC) templates is reported. This method can effectively create large‐area (>1 cm²), 3D surface patterns with well‐defined structures in a cost‐effective and time‐saving manner (<30 min). A variety of 3D surface patterns, including semishells, Janus particles, microcups, and mushroom‐like clusters, is generated. Most importantly, our method can be used to prepare surface patterns with prescribed compositions, such as metals, metal oxides, organic materials, or composites (e.g., metal/metal oxide, metal/polymer). The 3D surface patterns produced by our method can be valuable in a wide range of applications, such as biosensing, data storage, and plasmonics. In a proof‐of‐concept study, we investigated, both experimentally and theoretically, the surface‐enhanced Raman scattering (SERS) performance of the fabricated silver 3D semishell arrays.     

Record‐Low‐Threshold Lasers Based on Atomically Smooth Triangular Nanoplatelet Perovskite

Single‐crystalline perovskites are ideal candidates for lasing and other optoelectronic applications. Although significant efforts have been made to grow both bulk single‐crystalline perovskites in liquid solution, their dimensions are still too large to make nanoscale whispering‐gallery‐mode (WGM) resonator based lasers that possess high quality (Q) factor and small volume. Besides, most reported perovskite resonators do not possess atomically smooth surfaces and facets, which limits the Q and thereby increases the lasing threshold. Here, atomically smooth triangular PbI₂ templates are fabricated on a mica substrate by the vapor phase deposition method and are converted to atomically smooth perovskites which have regular and unwrinkled facets with average surface roughness less than 2 nm. By using a CH₃NH₃PbI₃ nanoplatelet with a side length of 27 µm and thickness of 80 nm, room temperature WGM lasing with a Q up to 2600 is demonstrated, the highest reported for hybrid organic–inorganic perovskite nanoplatelets. In addition, the volume of the WGM mode is reduced significantly in comparison with the prior reports. The realized high‐quality triangular CH₃NH₃PbI₃ perovskite nanoplatelets with high Q factor and small volume are expected to perform as ideal cavities for long pulse durations lasers and would find potential applications in integrated optoelectronic devices.