Engineering DNA-Guided Hydroxyapatite Bulk Materials with High Stiffness and Outstanding Antimicrobial Ability for Dental Inlay Applications

A Moldable, Tough Mineral-Dominated Nanocomposite as a Recyclable Structural Material

Flexible hybrid minerals, primarily composed of inorganic ionic crystal nanolines and a small amount of organic molecules, have significant potential for the development of sustainable structural materials. However, the weak interactions and insufficient crosslinking among the inorganic nanolines limit the mechanical enhancement and application of these hybrid minerals in high-strength structural materials. Inspired by tough biominerals and modern reinforced concrete structures, this study proposes introducing an aramid nanofiber (ANF) network as a flexible framework during the polymerization of calcium phosphate oligomers (CPO), crosslinked by polyvinyl alcohol (PVA) and sodium alginate (SA). This approach allows the flexible inorganic nanolines formed through CPO polymerization to be integrated into the organic framework, thereby creating tough mineral-based structural materials (inorganic content: 70.7 wt.%), denoted as PVA/SA/ANF/CPO (PSAC). The multiple intermolecular interactions between the organic and inorganic phases, combined with the integrated nano-reinforced concrete structure, endow PSAC with significantly enhanced tensile strength (86.6 ± 8.6 MPa), comparable to that of high-strength polymer plastics. Moreover, PSAC possesses excellent plasticity and flame retardancy. The noncovalent molecular interactions within PSAC enable efficient recyclability. Consequently, PSAC has the potential to replace high-strength polymer plastics and structural components, providing a promising avenue for developing high-strength and toughness mineral-based structural materials.

Biomimetic Janus Particles Induced In Situ Interfacial Remineralization for Dentin Hypersensitivity

Dentin hypersensitivity (DH), caused by the exposure of dentin tubules, is a common complaint of dental patients. Although occlusion of the exposed tubules is the primary treatment approach, the complex oral environment, and multiple simultaneous requirements often hinder its implementation. In this study, strawberry‐shaped hemispheric Janus particles (JPs) are synthesized, and their use in the treatment of DH is evaluated in vitro and in an animal model. The hemispheric side of the JPs is modified with polymers of quaternary ammonium salts (QASs) to form a superhydrophobic coating with antibiofilm properties, while the flat side is modified with catechol groups able to form strong bonds with dentin. Even after 1 h of ultrasonication or 1000 rounds of thermal cycling, the dentin tubules are completely occluded by the JPs. Moreover, biofilm formation is not observed, and the area of living bacteria is less than 1% compared to the blank control and sodium fluoride (NaF)‐treated groups. In a rat model, the dentin tubules in the fixed specimens are completely occluded at day 3, much earlier than the occlusion obtained with commonly used NaF. These results demonstrate that JPs can provide a novel approach to the treatment of DH.

Cationized Decalcified Bone Matrix for Infected Bone Defect Treatment

Objective: We aim to develop a dual-functional bone regeneration scaffold (Qx-D) with antibacterial and osteogenic properties for infected bone defect treatment. Impact Statement: This study provides insights into antibacterial components that could be combined with naturally derived materials through a facile Schiff base reaction, offering a potential strategy to enhance antibacterial properties. Introduction: Naturally derived decalcified bone matrix (DBM) has been reported to be porous and biodegradable. DBM can induce various cell differentiations and participate in immune regulation, making it an ideal bone regeneration scaffold for bone defects. However, DBM does not exhibit antimicrobial properties. Therefore, it is essential to develop antibacterial functionalization method for DBM. Methods: DBM was modified with a macromolecular quaternary ammonium salt (QPEI). A series of Qx-D with tunable feeding ratios were synthesized through Schiff base reaction. The morphology, chemical property, in vitro antibacterial efficiency, in vitro biocompatibility, osteogenic property, and in vivo anti-infection performances were characterized. Results: All Qx-D exhibited marked antibacterial properties. Small adjustments in feed concentration could not induce changes in antibacterial properties. However, cell viability slightly decreased with increasing feed concentration. Q10-D demonstrated significant antibacterial properties and could promote recovery of infected bone defect in an animal model. Conclusion: Qx-D shows marked antibacterial properties and good biocompatibility. Moreover, Q10-D could be a potential choice for infected bone defects.

Monolithic DNApatite: An Elastic Apatite with Sub-Nanometer Scale Organo-Inorganic Structures

Hydroxyapatite (HA) exhibits outstanding biocompatibility, bioactivity, osteoconductivity, and natural anti-inflammatory properties. Pure HA, ion-doped HA, and HA-polymer composites are investigated, but critical limitations such as brittleness remain; numerous efforts are being made to address them. Herein, the novel self-crystallization of a polymeric single-stranded deoxyribonucleic acid (ssDNA) without additional phosphate ions for synthesizing deoxyribonucleic apatite (DNApatite) is presented. The synthesized DNApatite, DNA1Ca2.2(PO4)1.3OH2.1, has a repetitive dual phase of inorganic HA crystals and amorphous organic ssDNA at the sub-nm scale, forming nanorods. Its mechanical properties, including toughness and elasticity, are significantly enhanced compared with those of HA nanorod, with a Young's modulus similar to that of natural bone.

Highly Regular Layered Structure via Dual-Spatially-Confined Alignment of Nanosheets Enables High-Performance Nanocomposites

Assembling ultrathin nanosheets into layered structure represents one promising way to fabricate high-performance nanocomposites. However, how to minimize the internal defects of the layered assemblies to fully exploit the intrinsic mechanical superiority of nanosheets remains challenging. Here, a dual-scale spatially confined strategy for the co-assembly of ultrathin nanosheets with different aspect ratios into a near-perfect layered structure is developed. Large-aspect-ratio (LAR) nanosheets are aligned due to the microscale confined space of a flat microfluidic channel, small-aspect-ratio (SAR) nanosheets are aligned due to the nanoscale confined space between adjacent LAR nanosheets. During this co-assembly process, SAR nanosheets can flatten LAR nanosheets, thus reducing wrinkles and pores of the assemblies. Benefiting from the precise alignment (orientation degree of 90.74%) of different-sized nanosheets, efficient stress transfer between nanosheets and interlayer matrix is achieved, resulting in layered nanocomposites with multiscale mechanical enhancement and superior fatigue durability (100 000 bending cycles). The proposed co-assembly strategy can be used to orderly integrate high-quality nanosheets with different sizes or diverse functions toward high-performance or multifunctional nanocomposites.

A Hydroxylamine-Mediated Amidination of Lysine Residues That Retains the Protein's Positive Charge

Lysine-specific peptide and protein modification strategies are widely used to study charge-related functions and applications. However, these strategies often result in the loss of the positive charge on lysine, significantly impacting the charge-related properties of proteins. Herein, we report a strategy to preserve the positive charge and selectively convert amines in lysine side chains to amidines using nitriles and hydroxylamine under aqueous conditions. Various unprotected peptides and proteins were successfully modified with a high conversion rate. Moreover, the reactive amidine moiety and derived modification site enable subsequent secondary modifications. Notably, positive charges were retained during the modification. Therefore, positive charge-related protein properties, such as liquid-liquid phase separation behaviour of α-synuclein, were not affected. This strategy was subsequently applied to a lysine rich protein to develop an amidine-containing coacervate DNA complex with outstanding mechanical properties. Overall, our innovative strategy provides a new avenue to explore the characteristics of positively charged proteins.

Self-assembled branched polypeptides as amelogenin mimics for enamel repair

The regeneration of demineralized enamel holds great significance in the treatment of dental caries. Amelogenin (Ame), an essential protein for mediating natural enamel growth, is no longer secreted after enamel has fully matured in childhood. Although biomimetic mineralization based on peptides or proteins has made significant progress, easily accessible, low-cost, biocompatible and highly effective Ame mimics are still lacking. Herein, we construct a series of amphiphilic branched polypeptides (CAMPs) by facile coupling of the Ame's C-terminal segment and poly(γ-benzyl-L-glutamate), which serves to simulate the Ame's hydrophobic N-terminal segment. Among them, CAMP15 is the best biomimetic mineralization template with great self-assembly performance to guide the oriented crystallization of hydroxyapatite and is capable of inhibiting the adhesion of Streptococcus mutans and Staphylococcus aureus on the enamel surfaces. This work highlights the potential application of amphiphilic branched polypeptide as Ame mimics in repairing defected enamel, providing a promising strategy for prevention and treatment of dental caries.

Multicomponent Synergistic Antibacterial Hydrogel Based on Gelatin-Oxidized Carboxymethyl Cellulose for Wound Healing of Drug-Resistant Chronic Infection

Bacterial invasion hinders the healing process of wound, leading to the formation of chronic infected wound; meanwhile, the misuse of antibiotics has resulted in the emergence of numerous drug-resistant bacteria. The application of conventional antimicrobial methods and wound treatment techniques is not appropriate for wound dressings. In this paper, quaternized poly(vinyl alcohol) (QPVA) and pomegranate-like copper uniformly doped polydopamine nanoparticles (PDA@Cu) were introduced into a gelatin-oxidized carboxymethyl cellulose system to form a multicomponent synergistic antibacterial hydrogel (GOQ3P3). Polydopamine improves the biocompatibility and prevents the detachment of Cu nanoparticles. It can achieve synergistic antibacterial effects through quaternary ammonium salt-inorganic nanoparticle photothermal treatment under 808 nm near-infrared (NIR) irradiation. It exhibits highly efficient and rapid bactericidal properties against Escherichia coli, Staphylococcus aureus, and MRSA (methicillin-resistant Staphylococcus aureus) with an antibacterial rate close to 100%. The gel scaffold composed of macromolecules gives the hydrogel excellent mechanical properties, adhesive capabilities, self-healing characteristics, biocompatibility, and pH degradation and promotes cell adhesion and migration. In a full-thickness wound healing model infected with MRSA, GOQ3P3 controls inflammatory responses, accelerates collagen deposition, promotes angiogenesis, and enhances wound closure in the wound healing cascade reaction. This study provides a feasible strategy for constructing dressings targeting chronic infection wounds caused by drug-resistant bacteria.

Tubular Nanoclay-Enhanced Calcium Phosphate Mineralization and Assembly to Impart High Stiffness and Antimicrobial Properties

Achieving superior mechanical properties of composite materials in artificially engineered materials is a great challenge due to technical bottlenecks in the size and morphological modulation of inorganic nanominerals. Hence, a "bioprocess-inspired fabrication" is proposed to create multilayered organic-inorganic columnar structures. The sequential assembly of halloysite nanotubes (HNTs), polyelectrolytes (PAAs), and calcium phosphates (CaPs) results in organic-inorganic structures. PAA plays a crucial role in controlling the formation of CaP, guiding it into amorphous particles with smaller nanosizes. The introduction of HNT induces the assembly and maturation of CaP-PAA, leading to the formation of a highly crystalline hydroxyapatite. Poly(vinyl alcohol) was then woven into HNT-encapsulated hydroxyapatite nanorods, resulting in composite materials with basic hierarchical structures across multiple scales. The fabricated composite exhibits exceptional hardness (4.27 ± 0.33 GPa) and flexural strength (101.25 ± 1.72 MPa), surpassing those of most previously developed biological hard tissue materials. Additionally, the composite demonstrates effective antibacterial properties and corrosion resistance, attributed to the dense crystalline phase of CaP. This innovative approach showcases the potential of clay minerals, particularly HNT, in the advancement of biomaterial design. The outstanding mechanical and antimicrobial properties of clay-based composites make them a promising candidate for applications in hard tissue repair, offering versatility in biomedicine and engineering.

Design and synthesis of bioinspired nanomaterials for biomedical application

Natural materials and bioprocesses provide abundant inspirations for the design and synthesis of high-performance nanomaterials. In the past several decades, bioinspired nanomaterials have shown great potential in the application of biomedical fields, such as tissue engineering, drug delivery, and cancer therapy, and so on. In this review, three types of bioinspired strategies for biomedical nanomaterials, that is, inspired by the natural structures, biomolecules, and bioprocesses, are mainly introduced. We summarize and discuss the design concepts and synthesis approaches of various bioinspired nanomaterials along with their specific roles in biomedical applications. Additionally, we discuss the challenges for the development of bioinspired biomedical nanomaterials, such as mechanical failure in wet environment, limitation in scale-up fabrication, and lack of deep understanding of biological properties. It is expected that the development and clinical translation of bioinspired biomedical nanomaterials will be further promoted under the cooperation of interdisciplinary subjects in future. This article is categorized under: Implantable Materials and Surgical Technologies > Nanomaterials and Implants Therapeutic Approaches and Drug Discovery > Emerging Technologies.

Construction of self-propelled micromotor for "hunting bacteria"

The inherent migration behavior of bacteria has inevitably impacted the advancement of the antibacterial treatment technology. Hunting bacteria, especially those with flagellates, requires self-propelled materials, which could kill bacteria autonomously. Herein, we designed and synthesized a self-propelled micromotor (SPM) tailed with poly(thiazole) to yield bimetallic organic frameworks (BiOFs), in which the assembly of BiOFs are similar to the "Newman projection". The moving speed of the obtained SPM was 238.6 μm s-1 and presented excellent antibacterial activity; more than 90% bacteria were hunted and killed in flowing water. Its minimum inhibitory concentration (MIC) against E. coli and S. aureus was 3.2 and 0.4 mg mL-1, respectively, and its antibacterial activity was still retained after recycling for 5 times. Its antibacterial mechanism along with the contribution of the active units and flow rate was investigated. In summary, a novel self-propelled material for hunting bacteria was synthesized by an unprecedented and efficient strategy. This approach is anticipated to create huge possibilities for its applications in the fields of antibacterial, disinfection, and microdevices.

Bio-Inspired Nanomaterials for Micro/Nanodevices: A New Era in Biomedical Applications

Exploring bio-inspired nanomaterials (BINMs) and incorporating them into micro/nanodevices represent a significant development in biomedical applications. Nanomaterials, engineered to imitate biological structures and processes, exhibit distinctive attributes such as exceptional biocompatibility, multifunctionality, and unparalleled versatility. The utilization of BINMs demonstrates significant potential in diverse domains of biomedical micro/nanodevices, encompassing biosensors, targeted drug delivery systems, and advanced tissue engineering constructs. This article thoroughly examines the development and distinctive attributes of various BINMs, including those originating from proteins, DNA, and biomimetic polymers. Significant attention is directed toward incorporating these entities into micro/nanodevices and the subsequent biomedical ramifications that arise. This review explores biomimicry's structure-function correlations. Synthesis mosaics include bioprocesses, biomolecules, and natural structures. These nanomaterials' interfaces use biomimetic functionalization and geometric adaptations, transforming drug delivery, nanobiosensing, bio-inspired organ-on-chip systems, cancer-on-chip models, wound healing dressing mats, and antimicrobial surfaces. It provides an in-depth analysis of the existing challenges and proposes prospective strategies to improve the efficiency, performance, and reliability of these devices. Furthermore, this study offers a forward-thinking viewpoint highlighting potential avenues for future exploration and advancement. The objective is to effectively utilize and maximize the application of BINMs in the progression of biomedical micro/nanodevices, thereby propelling this rapidly developing field toward its promising future.

Biomimetic Mineralization: From Microscopic to Macroscopic Materials and Their Biomedical Applications

Biomineralization is an attractive pathway to produce mineral-based biomaterials with high performance and hierarchical structures. To date, the biomineralization process and mechanism have been extensively studied, especially for the formation of bone, teeth, and nacre. Inspired by those, abundant biomimetic mineralized materials have been fabricated for biomedical applications. Those bioinspired materials generally exhibit great mechanical properties and biological functions. Nevertheless, substantial gaps remain between biomimetic materials and natural materials, particularly with respect to mechanical properties and mutiscale structures. This Review summarizes the recent progress of micro- and macroscopic biomimetic mineralization from the perspective of materials synthesis and biomedical applications. To begin with, we discuss the progress of biomimetic mineralization at the microscopic level. The mechanical strength, stability, and functionality of the nano- and micromaterials are significantly improved by introducing biominerals, such as DNA nanostructures, nanovaccines, and living cells. Next, numerous biomimetic strategies based on biomineralization at the macroscopic scale are highlighted, including in situ mineralization and bottom-up assembly of mineralized building blocks. Finally, challenges and future perspectives regarding the development of biomimetic mineralization are also presented with the aim of offering insights for the rational design and fabrication of next-generation biomimetic mineralized materials.

Advancing the Utility of DNA Origami Technique through Enhanced Stability of DNA-Origami-Based Assemblies

Since its discovery in 2006, the DNA origami technique has revolutionized bottom-up nanofabrication. This technique is simple yet versatile and enables the fabrication of nanostructures of almost arbitrary shapes. Furthermore, due to their intrinsic addressability, DNA origami structures can serve as templates for the arrangement of various nanoscale components (small molecules, proteins, nanoparticles, etc.) with controlled stoichiometry and nanometer-scale precision, which is often beyond the reach of other nanofabrication techniques. Despite the multiple benefits of the DNA origami technique, its applicability is often restricted by the limited stability in application-specific conditions. This Review provides an overview of the strategies that have been developed to improve the stability of DNA-origami-based assemblies for potential biomedical, nanofabrication, and other applications.

Fabrication of Bio-Based Film Comprising Metal Oxide Nanoparticles Loaded Chitosan for Wound Dressing Applications

In the current work, chitosan (CS)-metal oxide nanohybrid (MONH) composites are prepared via combining CS with MONH made of vanadium oxide (V₂O₅), ytterbium trioxide (Yb₂O₃), and graphene oxide (GO) to generate promising wound dressing materials using the film-casting method. The developed nanohybrid@CS was examined using techniques such as Fourier-transform infrared spectroscopy (FTIR), X-ray powder diffraction (XRD), scanning electron microscopy (SEM)/energy-dispersive X-ray spectroscopy (EDX), and thermogravimetric analysis (TGA). For Yb₂O₃@CS, the surface morphology was shown to be a rough and porous surface with pores that ranged in size from 3.0 to 5.0 µm. For CS with Yb₂O₃, Yb₂O₃/V₂O₅@CS, and Yb₂O₃/V₂O₅/GO@CS, the contact angles were 72.5°, 68.2°, and 46.5°, respectively. When the nanohybrid@CS was in its hydrophilic phase, which is good for absorbing moisture and drugs, there was a notable decrease in angles that tended to rise. Additionally, the inclusion of MONH allowed the cell viability to be confirmed with an IC₅₀ of 1997.2 g/mL and the cell growth to reach 111.3% at a concentration of 7.9 g/mL.

Preparation, applications, and challenges of functional DNA nanomaterials

As a carrier of genetic information, DNA is a versatile module for fabricating nanostructures and nanodevices. Functional molecules could be integrated into DNA by precise base complementary pairing, greatly expanding the functions of DNA nanomaterials. These functions endow DNA nanomaterials with great potential in the application of biomedical field. In recent years, functional DNA nanomaterials have been rapidly investigated and perfected. There have been reviews that classified DNA nanomaterials from the perspective of functions, while this review primarily focuses on the preparation methods of functional DNA nanomaterials. This review comprehensively introduces the preparation methods of DNA nanomaterials with functions such as molecular recognition, nanozyme catalysis, drug delivery, and biomedical material templates. Then, the latest application progress of functional DNA nanomaterials is systematically reviewed. Finally, current challenges and future prospects for functional DNA nanomaterials are discussed.

Bio-inspired special wettability in oral antibacterial applications

Most oral diseases originate from biofilms whose formation is originated from the adhesion of salivary proteins and pioneer bacteria. Therefore, antimicrobial materials are mainly based on bactericidal methods, most of which have drug resistance and toxicity. Natural antifouling surfaces inspire new antibacterial strategies. The super wettable surfaces of lotus leaves and fish scales prompt design of biomimetic oral materials covered or mixed with super wettable materials to prevent adhesion. Bioinspired slippery surfaces come from pitcher plants, whose porous surfaces are infiltrated with lubricating liquid to form superhydrophobic surfaces to reduce the contact with liquids. It is believed that these new methods could provide promising directions for oral antimicrobial practice, improving antimicrobial efficacy.