Porphyrin/Ionic-Liquid Co-assembly Polymorphism Controlled by Liquid-Liquid Phase Separation.

Understanding and controlling multicomponent co-assembly is of primary importance in different fields, such as materials fabrication, pharmaceutical polymorphism, and supramolecular polymerization, but these aspects have been a long-standing challenge. Herein, we discover that liquid-liquid phase separation (LLPS) into ion-cluster-rich and ion-cluster-poor liquid phases is the first step prior to co-assembly nucleation based on a model system of water-soluble porphyrin and ionic liquids. The LLPS-formed droplets serve as the nucleation precursors, which determine the resulting structures and properties of co-assemblies. Co-assembly polymorphism and tunable supramolecular phase transition behaviors can be achieved by regulating the intermolecular interactions at the LLPS stage. These findings elucidate the key role of LLPS in multicomponent co-assembly evolution and enable it to be an effective strategy to control co-assembly polymorphism as well as supramolecular phase transitions.

The Dominant Role of Oxygen in Modulating the Chemical Evolution Pathways of Tyrosine in Peptides: Dityrosine or Melanin.

In diverse biological systems, the oxidation of tyrosine to melanin or dityrosine is crucial for the formation of crosslinked proteins and thus for the realization of their structural, biological, and photoactive functionalities; however, the predominant factor in determining the pathways of this chemical evolution has not been revealed. Herein, we demonstrate for tyrosine-containing amino acid derivatives, peptides, and proteins that the selective oxidation of tyrosine to produce melanin or dityrosine can be readily realized by manipulating the oxygen concentration in the reaction system. This oxygen-dependent pathway selection reflects the selective chemical evolution of tyrosine to dityrosine and melanin in anaerobic and aerobic microorganisms, respectively. The resulting melanin- and dityrosine-containing nanomaterials reproduce key functions of their natural counterparts with respect to their photothermal and photoluminescent characteristics, respectively. This work reveals the plausible role of oxygen in the chemical evolution of tyrosine derivatives and provides a versatile strategy for the rational design of tyrosine-based multifunctional biomaterials.

Biomolecular glass with amino acid and peptide nanoarchitectonics.

Glass is ubiquitous in life and widely used in various fields. However, there is an urgent need to develop biodegradable and biorecyclable glasses that have a minimal environmental footprint toward a sustainable society and a circular materials economy. Here, we report a family of eco-friendly glasses of biological origin fabricated using biologically derived amino acids or peptides through the classic heating-quenching procedure. Amino acids and peptides with chemical modification at their ends are found able to form a supercooled liquid before decomposition and eventually glass upon quenching. These developed glasses exhibit excellent glass-forming ability and optical characteristics and are amenable to three-dimensional-printed additive manufacturing and mold casting. Crucially, the glasses show biocompatibility, biodegradability, and biorecyclability beyond the currently used commercial glasses and plastic materials.

Primitive Photosynthetic Architectures Based on Self-Organization and Chemical Evolution of Amino Acids and Metal Ions.

The emergence of light-energy-utilizing metabolism is likely to be a critical milestone in prebiotic chemistry and the origin of life. However, how the primitive pigment is spontaneously generated still remains unknown. Herein, a primitive pigment model based on adaptive self-organization of amino acids (Cystine, Cys) and metal ions (zinc ion, Zn2+) followed by chemical evolution under hydrothermal conditions is developed. The resulting hybrid microspheres are composed of radially aligned cystine/zinc (Cys/Zn) assembly decorated with carbonate-doped zinc sulfide (C-ZnS) nanocrystals. The part of C-ZnS can work as a light-harvesting antenna to capture ultraviolet and visible light, and use it in various photochemical reactions, including hydrogen (H2) evolution, carbon dioxide (CO2) photoreduction, and reduction of nicotinamide adenine dinucleotide (NAD+) to nicotinamide adenine dinucleotide hydride (NADH). Additionally, guest molecules (e.g., glutamate dehydrogenase, GDH) can be encapsulated within the hierarchical Cys/Zn framework, which facilitates sustainable photoenzymatic synthesis of glutamate. This study helps deepen insight into the emergent functionality (conversion of light energy) and complexity (hierarchical architecture) from interaction and reaction of prebiotic molecules. The primitive pigment model is also promising to work as an artificial photosynthetic microreactor.

Amino-Acid-Mediated Biomimetic Formation of Light-Harvesting Antenna Capable of Hydrogen Evolution.

The control of materials concerning size as well as high-order organization may have profound implications for a wide variety of technologies. Herein, we develop a facile strategy to fabricate hierarchically organized amino acid and quantum dot (QD) biomimetic light-harvesting antenna via the integration of coordination-driven self-assembly and bioinspired mineralization. Simplified from phytochelatins, cystine is used as a chelating agent to bind cadmium ions (Cd2+). This coordination interaction further drives the self-assembly of cystine into hierarchical hybrid crystals. The hybrid templates can provide ordered sites for in situ mineralization of cadmium sulfide (CdS) to generate hierarchical three-dimensional QDs architectures. Optimal light harvesting properties are obtained by controlling the mineralization conditions, which facilitates photocatalytic hydrogen (H2) evolution. In addition, the CdS QDs architectures possess sustainable photocatalytic performance because of robust assembled structures, rendering them potent candidates for optoelectronic applications.

Modulated regeneration of acid-etched human tooth enamel by a functionalized dendrimer that is an analog of amelogenin.

In the bioinspired repair process of tooth enamel, it is important to simultaneously mimic the organic-matrix-induced biomineralization and increase the binding strength at the remineralization interface. In this work, a fourth-generation polyamidoamine dendrimer (PAMAM) is modified by dimethyl phosphate to obtain phosphate-terminated dendrimer (PAMAM-PO3H2) since it has a similar dimensional scale and peripheral functionalities to that of amelogenin, which plays important role in the natural development process of enamel. Its phosphate group has stronger affinity for calcium ion than carboxyl group and can simultaneously provide strong hydroxyapatite (HA)-binding capability. The MTT assay demonstrates the low cytotoxicity of PAMAM-PO3H2. Adsorption tests indicate that PAMAM-PO3H2 can be tightly adsorbed on the human tooth enamel. Scanning electron microscopy and X-ray diffraction are used to analyze the remineralization process. After being incubated in artificial saliva for 3weeks, there is a newly generated HA layer of 11.23µm thickness on the acid-etched tooth enamel treated by PAMAM-PO3H2, while the thickness for the carboxyl-terminated one (PAMAM-COOH) is only 6.02µm. PAMAM-PO3H2 can regulate the remineralization process to form ordered new crystals oriented along the Z-axis and produce an enamel prism-like structure that is similar to that of natural tooth enamel. The animal experiment also demonstrates that PAMAM-PO3H2 can induce significant HA regeneration in the oral cavity of rats. Thus PAMAM-PO3H2 shows great potential as a biomimetic restorative material for human tooth enamel.