Biomineral-Inspired Colloidal Liquid Crystals: From Assembly of Hybrids Comprising Inorganic Nanocrystals and Organic Polymer Components to Their Functionalization

2D Photonic Colloidal Liquid Crystals Composed of Self-Assembled Rod-Shaped Particles

Photonic crystals, characterized by their periodic structures, have been extensively studied for their ability to manipulate light. Typically, the development of 2D photonic crystals requires either sophisticated equipment or precise orientation of spherical nanoparticles. However, liquid-crystalline (LC) materials offer a promising alternative, facilitating the formation of periodic structures without the need for complex manipulation. Despite this advantage, the development of 2D photonic periodic structures using LC materials is limited to a few colloidal nanodisk liquid crystals. Herein, 2D photonic colloidal liquid crystals composed of biomineral-based nanorods and water is reported. The soft photonic materials with 2D structure by self-assembled LC colloidal nanorods are unique and a new class of photonic materials different from conventional solid 2D photonic materials. These colloids exhibit bright structural colors with high reflectance (>50%) and significant angular dependency. The structural colors are adjusted by controlling the concentration and size of the LC colloidal nanorods. Furthermore, mechanochromic hydrogel thin films with 2D photonic structure are developed. The hydrogels exhibit reversible mechanochromic properties with angular dependency, which can be used for an advanced stimuli responsible sensor.

A Novel Dinuclear Complex-PLC Composite Material as Fluorescent Switch in Treatment on Osteoarthritis

In this study, we synthesized a novel Co(II)-containing coordination compound (CP) [Co2(MMBA)2(HPT)2(H2O)2]·2H2O (1) through a solvothermal reaction of Co(NO3)6·6H2O with 3-(pyridin-2-yl)-1 H-1,2,4-triazole (HPT) and 2-(4-methylbenzoyl)benzoic acid (HMMBA). Fluorescence spectroscopy confirmed that this compound exhibited superior blue fluorescence properties compared to the original ligands. Further, aspirin (ASA) was loaded onto this CP via physical adsorption to create CP-ASA. Interestingly, the fluorescence properties of the CP decreased with the loading of the drug but were restored upon drug release. Leveraging the unique optical properties and biocompatibility of Polymer Liquid Crystal (PLC), we further encapsulated CP-ASA, forming the CP-PLC@ASA composite. The target product was confirmed through various characterization techniques including Elemental Analysis (EA), Fourier-Transform Infrared Spectroscopy (FT-IR), Powder X-Ray Diffraction (PXRD), and Thermogravimetric Analysis (TGA). Moreover, the biological activity of this composite was evaluated in vitro for osteoarthritis, and its potential mechanisms were explored.

Monodisperse nanosheet mesophases

Self-assemblies of anisotropic colloidal particles into colloidal liquid crystals and well-defined superlattices are of great interest for hierarchical nanofabrications that are applicable for various functional materials. Inorganic nanosheets obtained by exfoliation of layered crystals have been highlighted as the intriguing colloidal units; however, the size polydispersity of the nanosheets has been preventing precise design of the assembled structures and their functions. Here, we demonstrate that the anionic titanate nanosheets with monodisperse size reversibly form very unusual superstructured mesophases through finely tunable weak attractive interactions between the nanosheets. Transmission electron microscopy, polarizing optical microscopy, small-angle x-ray scattering, and confocal laser scanning microscopy clarified the reversible formation of the mesophases (columnar nanofibers, columnar nematic liquid crystals, and columnar nanofiber bundles) as controlled by counter cations, nanosheet concentration, solvent, and temperature.

Biomineral-Based Composite Materials in Regenerative Medicine

Regenerative medicine aims to address substantial defects by amplifying the body's natural regenerative abilities and preserving the health of tissues and organs. To achieve these goals, materials that can provide the spatial and biological support for cell proliferation and differentiation, as well as the micro-environment essential for the intended tissue, are needed. Scaffolds such as polymers and metallic materials provide three-dimensional structures for cells to attach to and grow in defects. These materials have limitations in terms of mechanical properties or biocompatibility. In contrast, biominerals are formed by living organisms through biomineralization, which also includes minerals created by replicating this process. Incorporating biominerals into conventional materials allows for enhanced strength, durability, and biocompatibility. Specifically, biominerals can improve the bond between the implant and tissue by mimicking the micro-environment. This enhances cell differentiation and tissue regeneration. Furthermore, biomineral composites have wound healing and antimicrobial properties, which can aid in wound repair. Additionally, biominerals can be engineered as drug carriers, which can efficiently deliver drugs to their intended targets, minimizing side effects and increasing therapeutic efficacy. This article examines the role of biominerals and their composite materials in regenerative medicine applications and discusses their properties, synthesis methods, and potential uses.

Fucoidan-hybrid hydroxyapatite nanoparticles promote the osteogenic differentiation of human periodontal ligament stem cells under inflammatory condition

Inflammation-related bone defects often lead to poor osteogenesis. Therefore, it is crucial to reduce the inflammation response and promote the osteogenic differentiation of stem/progenitor cells to revitalize bone physiology. Here, a kind of hybrid nano-hydroxyapatite was prepared using the confined phosphate ion release method with the participation of fucoidan, a marine-sourced polysaccharide with anti-inflammation property. The physicochemical analyses confirmed that the fucoidan hybrid nano-hydroxyapatite (FC/n-HA) showed fine needle-like architectures. With a higher amount of fucoidan, the crystal size and crystallinity of the FC/n-HA reduced while the liquid dispersibility was improved. Cell experiences showed that FC/n-HA had an optimal cytocompatibility at concentration of 50 μg/mL. Moreover, the lipopolysaccharide-induced cellular inflammatory model with PDLSCs was established and used to evaluate the anti-inflammatory and osteogenic properties. For the 1%FC/n-HA group, the expression levels of TNF-α and IL-1β were significantly reduced at 24 h, while the expression of alkaline phosphatase of PDLSCs was significantly promoted at days 3 and 7, and calcium precipitates was enhanced at 21 days. In this study, the FC/n-HA particles showed effective anti-inflammatory properties and facilitated osteogenic differentiation of PDLSCs, indicating which has potential application in treating bone defects associated with inflammation, such as periodontitis.

Guidelines derived from biomineralized tissues for design and construction of high-performance biomimetic materials: from weak to strong

Living organisms in nature have undergone continuous evolution over billions of years, resulting in the formation of high-performance fracture-resistant biomineralized tissues such as bones and teeth to fulfill mechanical and biological functions, despite the fact that most inorganic biominerals that constitute biomineralized tissues are weak and brittle. During the long-period evolution process, nature has evolved a number of highly effective and smart strategies to design chemical compositions and structures of biomineralized tissues to enable superior properties and to adapt to surrounding environments. Most biomineralized tissues have hierarchically ordered structures consisting of very small building blocks on the nanometer scale (nanoparticles, nanofibers or nanoflakes) to reduce the inherent weaknesses and brittleness of corresponding inorganic biominerals, to prevent crack initiation and propagation, and to allow high defect tolerance. The bioinspired principles derived from biomineralized tissues are indispensable for designing and constructing high-performance biomimetic materials. In recent years, a large number of high-performance biomimetic materials have been prepared based on these bioinspired principles with a large volume of literature covering this topic. Therefore, a timely and comprehensive review on this hot topic is highly important and contributes to the future development of this rapidly evolving research field. This review article aims to be comprehensive, authoritative, and critical with wide general interest to the science community, summarizing recent advances in revealing the formation processes, composition, and structures of biomineralized tissues, providing in-depth insights into guidelines derived from biomineralized tissues for the design and construction of high-performance biomimetic materials, and discussing recent progress, current research trends, key problems, future main research directions and challenges, and future perspectives in this exciting and rapidly evolving research field.

Nanostructure Control in Zinc Oxide Films and Microfibers through Bioinspired Synthesis of Liquid-Crystalline Zinc Hydroxide Carbonate; Formation of Free-Standing Materials in Centimeter-Level Lengths

Free-standing zinc oxide in the forms of films and fibrous materials are expected to be used as functional devices such as piezoelectric devices and catalyst filters without being limited by the growth substrate. Herein, a synthetic morphology-control method for 2D and 1D free-standing ZnO materials with ordered and nanoporous structures by conversion of liquid-crystalline (LC) zinc hydroxide carbonate (ZHC) nanoplates is reported. As a new colloidal liquid crystal, the LC ZHC nanoplate precursors are obtained by a biomineralization-inspired method. The approach is to control the morphology and crystallographic orientation of ZHC crystals by using acidic macromolecules. Their nano-scale and oriented structures are examined. The LC oriented ZHC nanoplates have led to the synthesis of free-standing films and microfibers of ZHC in centimeter-level lengths, with the successful thermal conversion into free-standing films and microfibers of ZnO. The resultant ZnO films and ZnO microfibers have nanoporous structures and preferential crystallographic orientations that preserve the alignment of ZHC nanoplates before conversion.

Aquatic Functional Liquid Crystals: Design, Functionalization, and Molecular Simulation

Aquatic functional liquid crystals, which are ordered molecular assemblies that work in water environment, are described in this review. Aquatic functional liquid crystals are liquid-crystalline (LC) materials interacting water molecules or aquatic environment. They include aquatic lyotropic liquid crystals and LC based materials that have aquatic interfaces, for example, nanoporous water treatment membranes that are solids preserving LC order. They can remove ions and viruses with nano- and subnano-porous structures. Columnar, smectic, bicontinuous LC structures are used for fabrication of these 1D, 2D, 3D materials. Design and functionalization of aquatic LC sensors based on aqueous/LC interfaces are also described. The ordering transitions of liquid crystals induced by molecular recognition at the aqueous interfaces provide distinct optical responses. Molecular orientation and dynamic behavior of these aquatic functional LC materials are studied by molecular dynamics simulations. The molecular interactions of LC materials and water are key of these investigations. New insights into aquatic functional LC materials contribute to the fields of environment, healthcare, and biotechnology.

Cubosomes-assisted transdermal delivery of doxorubicin and indocyanine green for chemo-photothermal combination therapy of melanoma

Melanoma is a highly aggressive form of skin cancer with limited therapeutic options. Chemo-photothermal combination therapy has demonstrated potential for effectively treating melanoma, and transdermal administration is considered the optimal route for treating skin diseases due to its ability to bypass first-pass metabolism and enhance drug concentration. However, the stratum corneum presents a formidable challenge as a significant barrier to drug penetration in transdermal drug delivery. Lipid-nanocarriers, particularly cubosomes, have been demonstrated to possess significant potential in augmenting drug permeation across the stratum corneum. Herein, cubosomes co-loaded with doxorubicin (DOX, a chemotherapeutic drug) and indocyanine green (ICG, a photothermal agent) (DOX-ICG-cubo) transdermal drug delivery system was developed to enhance the therapeutic efficiency of melanoma by improving drug permeation. The DOX-ICG-cubo showed high encapsulation efficiency of both DOX and ICG, and exhibited good stability under physiological conditions. In addition, the unique cubic structure of the DOX-ICG-cubo was confirmed through transmission electron microscopy (TEM) images, polarizing microscopy, and small angle X-ray scattering (SAXS). The DOX-ICG-cubo presented high photothermal conversion efficiency, as well as pH and thermo-responsive DOX release. Notably, the DOX-ICG-cubo exhibited enhanced drug permeation efficiency, good biocompatibility, and improved in vivo anti-melanoma efficacy through the synergistic effects of chemo-photothermal therapy. In conclusion, DOX-ICG-cubo presented a promising strategy for melanoma treatment.

Experimental probing of dynamic self-organized columnar assemblies in colloidal liquid crystals

Self-organized supramolecular assemblies are widespread in nature and technology in the form of liquid crystals, colloids, and gels. The reversible nature of non-covalent bonding leads to dynamic functions such as stimuli-responsive switching and self-healing, which are unachievable from an isolated molecule. However, multiple intermolecular interactions generate diverse conformational and configurational molecular motions over various time scales in their self-assembled states, and their specific dynamics remains unclear. In the present study, we have experimentally unveiled the static structures and dynamical behaviors in columnar colloidal liquid crystals by a coherent X-ray scattering technique using refined model samples. We have found that controlling the size distribution of the colloidal nanoplates dramatically changed their static and dynamic properties. Furthermore, the resulting dynamical behaviors obtained by X-ray photon correlation spectroscopy have been successfully decomposed into multiple distinct modes, allowing us to explore the dynamical origin in the colloidal liquid-crystalline state. The present approaches using a columnar liquid crystal may contribute to a better understanding of the dynamic nature of molecular assemblies and dense colloidal systems and bring valuable insights into rational design of functional properties of self-assembled materials such as stimuli-responsive liquid crystals, self-healing gels, and colloidal crystals. For these materials, the motion of constituent particles and molecules in the self-assembled state is a key factor for structural formation and dynamically responsive performance.