High Mechanical Strength Alloy-like Minerals Prepared by Inorganic Ionic Co-cross-linking.

Alloys often combine different metals to generate superior mechanical properties. However, it is challenging to prepare high mechanical strength minerals with similar strategies. Using calcium carbonate (CaC) and calcium phosphate (CaP) as examples, this work synthesizes a group of compounds with the chemical formulas Ca(CO3 )x (PO4 )2(1- x )/3 (0 < x < 1, CaCPs) by cross-linking ionic oligomers. Unlike mixtures, these CaCPs exhibit a single temperature for the phase transition from amorphous to crystallized CaC (calcite) and CaP (hydroxyapatite). By heat-induced synchronous crystallization, dual-phase CaC/CaP with continuous crystallized boundaries are resembled to alloy-like minerals (ALMs). The mechanical properties of the ALMs are adjusted by tailoring their chemical compositions to reach a hardness of 5.6 GPa, which exceed those of control calcite and hydroxyapatite samples by 430% and 260%, respectively. This strategy expands the chemical scope of inorganic materials and holds promise for preparing high-performance minerals.

Microalgae-material hybrid for enhanced photosynthetic energy conversion: a promising path towards carbon neutrality.

Photosynthetic energy conversion for high-energy chemicals generation is one of the most viable solutions in the quest for sustainable energy towards carbon neutrality. Microalgae are fascinating photosynthetic organisms, which can directly convert solar energy into chemical energy and electrical energy. However, microalgal photosynthetic energy has not yet been applied on a large scale due to the limitation of their own characteristics. Researchers have been inspired to couple microalgae with synthetic materials via biomimetic assembly and the resulting microalgae-material hybrids have become more robust and even perform new functions. In the past decade, great progress has been made in microalgae-material hybrids, such as photosynthetic carbon dioxide fixation, photosynthetic hydrogen production, photoelectrochemical energy conversion and even biochemical energy conversion for biomedical therapy. The microalgae-material hybrid offers opportunities to promote artificially enhanced photosynthesis research and synchronously inspires investigation of biotic-abiotic interface manipulation. This review summarizes current construction methods of microalgae-material hybrids and highlights their implication in energy and health. Moreover, we discuss the current problems and future challenges for microalgae-material hybrids and the outlook for their development and applications. This review will provide inspiration for the rational design of the microalgae-based semi-natural biohybrid and further promote the disciplinary fusion of material science and biological science.

Immunization against Zika by entrapping live virus in a subcutaneous self-adjuvanting hydrogel.

The threat of new viral outbreaks has heightened the need for ready-to-use vaccines that are safe and effective. Here we show that a subcutaneous vaccine consisting of live Zika virus electrostatically entrapped in a self-adjuvanting hydrogel recruited immune cells at the injection site and provided mice with effective protection against a lethal viral challenge. The hydrogel prevented the escape of the viral particles and upregulated pattern recognition receptors that activated innate antiviral immunity. The local inflammatory niche facilitated the engulfment of the virus by immune cells infiltrating the hydrogel, the processing and cross-presentation of antigens and the expansion of germinal centre B cells and induced robust antigen-specific adaptive responses and immune memory. Inflammatory immune niches entrapping live viruses may facilitate the rapid development of safe and efficacious vaccines.

A Flexible and Degradable Hybrid Mineral as a Plastic Substitute.

The development of environmentally friendly plastics is critical to ensure sustainable development. In contrast to polymer plastics derived from petrochemicals, inorganic minerals, which are the most abundant matter in Earth's crust, are environmentally friendly. However, the brittleness of these minerals limits their applications as plastics. Here, because of the advantages of both biomineralization and inorganic ionic polymerization, the calcium phosphate (CaP, a typical geological and biological mineral) oligomers are used for biomimetic mineralization under the regulation of polyvinyl alcohol and sodium alginate, resulting in flexible CaP nanofibers with periodic structural defects. The assembly of CaP nanofibers produces a hierarchically structured bulk hybrid mineral (HM), which overcomes the intrinsic brittleness of minerals and exhibits plasticity characteristics. HM exhibits better hardness and thermostability than classical polymer plastics due to its dominant mineral composition. Notably, HM is environmentally friendly and degradable in nature, as it can potentially participate in geological cycles, indicating that this material is an optimal plastic substitute. The construction of periodic structural defects within flexible minerals expands the current understanding of materials science.

Crosslinking ionic oligomers as conformable precursors to calcium carbonate.

Inorganic materials have essential roles in society, including in building construction, optical devices, mechanical engineering and as biomaterials1-4. However, the manufacture of inorganic materials is limited by classical crystallization5, which often produces powders rather than monoliths with continuous structures. Several precursors that enable non-classical crystallization-such as pre-nucleation clusters6-8, dense liquid droplets9,10, polymer-induced liquid precursor phases11-13 and nanoparticles14-have been proposed to improve the construction of inorganic materials, but the large-scale application of these precursors in monolith preparations is limited by availability and by practical considerations. Inspired by the processability of polymeric materials that can be manufactured by crosslinking monomers or oligomers15, here we demonstrate the construction of continuously structured inorganic materials by crosslinking ionic oligomers. Using calcium carbonate as a model, we obtain a large quantity of its oligomers (CaCO3)n with controllable molecular weights, in which triethylamine acts as a capping agent to stabilize the oligomers. The removal of triethylamine initiates crosslinking of the (CaCO3)n oligomers, and thus the rapid construction of pure monolithic calcium carbonate and even single crystals with a continuous internal structure. The fluid-like behaviour of the oligomer precursor enables it to be readily processed or moulded into shapes, even for materials with structural complexity and variable morphologies. The material construction strategy that we introduce here arises from a fusion of classic inorganic and polymer chemistry, and uses the same cross-linking process for the manufacture the materials.

Improving the Charge Carrier Transport and Suppressing Recombination of Soluble Squaraine-Based Solar Cells via Parallel-Like Structure.

Small molecule organic solar cells (SMOSCs) have attracted extensive attention in recent years. Squaraine (SQ) is a kind of small molecule material for potential use in high-efficiency devices, because of its high extinction coefficient and low-cost synthesis. However, the charge carrier mobility of SQ-based film is much lower than other effective materials, which leads to the pretty low fill factor (FF). In this study, we improve the performance of SQ derivative-based solar cells by incorporating PCDTBT into LQ-51/PC71BM host binary blend film. The incorporation of PCDTBT can not only increase the photon harvesting, but also provide an additional hole transport pathway. Through the charge carrier mobility and transient photovoltage measurement, we find that the hole mobility and charge carrier lifetime increase in the ternary system. Also, we carefully demonstrate that the charge carrier transport follows a parallel-like behavior.

Improvement in the Photobiological Hydrogen Production of Aggregated Chlorella by Dimethyl Sulfoxide.

Photobiological hydrogen production plays a vital role in generating clean renewable energy owing to its low energy consumption and environmental friendliness. Although materials-induced Chlorella aggregates have been developed to achieve sustained photobiological hydrogen production under normal aerobic conditions, the yield is relatively low and equals only 0.42 % of the light-to-H2 energy-conversion efficiency. Herein, we report that only 0.5 vol % dimethyl sulfoxide in an aqueous environment significantly enhances the H2 yield produced by aggregated Chlorella, reaching 0.69 % of the light-to-H2 energy-conversion efficiency. This improvement can be attributed to an increase in the cellular respiration rate by dimethyl sulfoxide, which results in a decrease in the oxygen content inside the aggregates and, ultimately, to the activation of more hydrogenases. More generally, this strategy consists of a functional enhancement in organism-material hybrids by using small molecules.

Improving the photovoltaic performance of planar heterojunction perovskite solar cells by mixed solvent vapor treatment.

The grain size of perovskite films is a key factor to optimize the performance of perovskite photovoltaic devices. Herein, a new route is developed in this paper to prepare CH3NH3PbI3 (MAPbI3) films with a better morphology and crystallization. This method includes the spin coating deposition of perovskite films with a precursor solution of PbI2 and CH3NH3I at the molar ratio 1 : 1 and thermal annealing (TA). The thermal annealing is conducted with a thermal-induced process to realize grain growth with solvent evaporation. In addition, a mixed solvent vapor treatment in acetic acid with chlorobenzene (HAc/CB) improves the morphology and crystallization of films further. As a result, the photovoltaic device based on the perovskite film treated by mixed HAc/CB solvent exhibits the best efficiency of 13.15% in comparison to the control device with 11.44% under AM 1.5G irradiation (100 mW cm-2).

Long-term Effect of Biomineralized Insulin Nanoparticles on Type 2 Diabetes Treatment.

Intracellular insulin may exhibit a long-term effect in regulating protein synthesis, DNA synthesis, and gene transcription. However, the intracellular delivery of insulin is a great challenge. Here, we describe how a simple biomineralization modification of insulin can transport it into intact cells on a large scale, leading to a long-term therapeutic effect on diabetes mellitus. Using insulin-resistant HepG2 cell and diabetic KKAy mice as models, in vitro and in vivo assessments have demonstrated that biomineralized insulin nanoparticles can trigger glucose metabolism, and this improvement extends after the treatment. The potential exists to improve the current treatment of type 2 diabetes mellitus through biomineralized modifications of insulin. This study provides a new paradigm of biomimetic nanotechnology for biomedical applications.

Prevention of Cyanobacterial Blooms Using Nanosilica: A Biomineralization-Inspired Strategy.

Cyanobacterial blooms represent a significant threat to global water resources because blooming cyanobacteria deplete oxygen and release cyanotoxins, which cause the mass death of aquatic organisms. In nature, a large biomass volume of cyanobacteria is a precondition for a bloom, and the cyanobacteria buoyancy is a key parameter for inducing the dense accumulation of cells on the water surface. Therefore, blooms will likely be curtailed if buoyancy is inhibited. Inspired by diatoms with naturally generated silica shells, we found that silica nanoparticles can be spontaneously incorporated onto cyanobacteria in the presence of poly(diallyldimethylammonium chloride), a cationic polyelectrolyte that can simulate biosilicification proteins. The resulting cyanobacteria-SiO2 complexes can remain sedimentary in water. This strategy significantly inhibited the photoautotrophic growth of the cyanobacteria and decreased their biomass accumulation, which could effectively suppress harmful bloom events. Consequently, several of the adverse consequences of cyanobacteria blooms in water bodies, including oxygen consumption and microcystin release, were significantly alleviated. Based on the above results, we propose that the silica nanoparticle treatment has the potential for use as an efficient strategy for preventing cyanobacteria blooms.

Water-resistant, monodispersed and stably luminescent CsPbBr3/CsPb2Br5 core-shell-like structure lead halide perovskite nanocrystals.

Lead halide perovskite materials are thriving in optoelectronic applications due to their excellent properties, while their instability due to the fact that they are easily hydrolyzed is still a bottleneck for their potential application. In this work, water-resistant, monodispersed and stably luminescent cesium lead bromine perovskite nanocrystals coated with CsPb2Br5 were obtained using a modified non-stoichiometric solution-phase method. CsPb2Br5 2D layers were coated on the surface of CsPbBr3 nanocrystals and formed a core-shell-like structure in the synthetic processes. The stability of the luminescence of the CsPbBr3 nanocrystals in water and ethanol atmosphere was greatly enhanced by the photoluminescence-inactive CsPb2Br5 coating with a wide bandgap. The water-stable enhanced nanocrystals are suitable for long-term stable optoelectronic applications in the atmosphere.

Switchable Chiral Selection of Aspartic Acids by Dynamic States of Brushite.

We herein show the chiral recognition and separation of aspartic acid (Asp) enantiomers by achiral brushite due to the asymmetries of their dynamical steps in its nonequilibrium states. Growing brushite has a higher adsorption affinity to d-Asp, while l-Asp is predominant on the dissolving brushite surface. Microstructural characterization reveals that chiral selection is mainly attributed to brushite [101] steps, which exhibit two different configurations during crystal growth and dissolution, respectively, with each preferring a distinct enantiomer due to this asymmetry. Because these transition step configurations have different stabilities, they subsequently result in asymmetric adsorption. By varying free energy barriers through solution thermodynamic driving force (i.e., supersaturation), the dominant nonequilibrium intermediate states can be switched and chiral selection regulated. This finding highlights that the dynamic steps can be vital for chiral selection, which may provide a potential pathway for chirality generation through the dynamic nature.

Protection of Photosynthetic Algae against Ultraviolet Radiation by One-Step CeO2 Shellization.

Photosynthetic microalgae play an important role in solar-to-chemical energy conversion on Earth, but the increasing solar ultraviolet (UV) radiation seriously reduces the biological photosynthesis. Here, we developed a one-step approach to construct cell-in-shell hybrid structure by using direct adsorption of CeO2 nanoparticles onto cells. The engineered CeO2 nanoshell can efficiently protect the enclosed Chlorella cell due to its excellent UV filter property, which can also eliminate UV-induced oxidative stress. The experiments demonstrate that the resulted algae-CeO2 composites can guarantee their biological photosynthetic process and efficiency even under UV. This study follows a feasible strategy to protect living organisms by using functional nanomaterials to improve their biological functions.

Biomimetic inorganic camouflage circumvents antibody-dependent enhancement of infection.

Pre-existing antibodies can aggravate disease during subsequent infection or vaccination via the mechanism of antibody-dependent enhancement (ADE) of infection. Herein, using dengue virus (DENV) as a model, we present a versatile surface-camouflage strategy to obtain a virus core-calcium phosphate shell hybrid by self-templated biomineralization. The shelled DENV stealthily avoids recognition by pre-existing antibodies under extracellular conditions, resulting in the efficient abrogation of the ADE of infection both in vitro and in vivo. Moreover, the nanoshell can spontaneously degrade under intracellular conditions to restore the virus activity and immunogenicity due to its pH-sensitive behaviour. This work demonstrates that the biomimetic material shell can significantly improve the administration safety and potency of the DENV vaccine, which provides the promising prospect of chemically designed virus-material hybrids for immune evasion.

Cells Recognize and Prefer Bone-like Hydroxyapatite: Biochemical Understanding of Ultrathin Mineral Platelets in Bone.

Hydroxyapatite (HAP) nanocrystallites in all types of bones are distinguished by their ultrathin characteristics, which are uniaxially oriented with fibrillar collagen to uniquely expose the (100) faces. We speculate that living organisms prefer the specific crystal morphology and orientation of HAP because of the interactions between cells and crystals at the mineral-cell interface. Here, bone-like platy HAP (p-HAP) and two different rod-like HAPs were synthesized to investigate the ultrathin mineral modulating effect on cell bioactivity and bone generation. Cell viability and osteogenic differentiation of mesenchymal stem cells (MSCs) were significantly promoted by the platy HAP with (100) faces compared to rod-like HAPs with (001) faces as the dominant crystal orientation, which indicated that MSCs can recognize the crystal face and prefer the (100) HAP faces. This face-specific preference is dependent on the selective adsorption of fibronectin (FN), a plasma protein that plays a central role in cell adhesion, on the HAP surface. This selective adsorption is further confirmed by molecule dynamics (MD) simulation. Our results demonstrate that it is an intelligent choice for cells to use ultrathin HAP with a large (100) face as a basic building block in the hierarchical structure of bone, which is crucial to the promotion of MSCs osteoinductions during bone formation.

Shape-Controlled Synthesis of All-Inorganic CsPbBr3 Perovskite Nanocrystals with Bright Blue Emission.

We developed a colloidal synthesis of CsPbBr3 perovskite nanocrystals (NCs) at a relative low temperature (90 °C) for the bright blue emission which differs from the original green emission (∼510 nm) of CsPbBr3 nanocubes as reported previously. Shapes of the obtained CsPbBr3 NCs can be systematically engineered into single and lamellar-structured 0D quantum dots, as well as face-to-face stacking 2D nanoplatelets and flat-lying 2D nanosheets via tuning the amounts of oleic acid (OA) and oleylamine (OM). They exhibit sharp excitonic PL emissions at 453, 472, 449, and 452 nm, respectively. The large blue shift relative to the emission of CsPbBr3 bulk crystal can be ascribed to the strong quantum confinement effects of these various nanoshapes. PL decay lifetimes are measured, ranging from several to tens of nanoseconds, which infers the higher ratio of exciton radiative recombination to the nonradiative trappers in the obtained CsPbBr3 NCs. These shape-controlled CsPbBr3 perovskite NCs with the bright blue emission will be widely used in optoelectronic applications, especially in blue LEDs which still lag behind compared to the better developed red and green LEDs.

Biomineralized vaccine nanohybrid for needle-free intranasal immunization.

Frequent outbreaks and the rapid global spread of infectious diseases have increased the urgent need for massive vaccination especially in countries with limited resources. Intranasal vaccination facilitates the mass vaccination via needle-free delivery of vaccine through nasal mucosal surfaces. Inspired by the strong capability of calcium phosphate (CaP) materials to adhere to cells and tissues, we propose to improve nasal vaccination by using a biomineralization-based strategy. The vaccine nanohybrid was obtained by covering the viral surface with CaP nanoshell, which changed the physiochemical properties of original vaccine, resulting in the increase of mucosal adhesion to the nasal tissues. The core-shell structure was beneficial for the receptor-independent uptake and the induction of elevated local IgA response within the nasal cavity. Moreover, the vaccine complex elicited enhanced systemic antibody response that neutralized wild type of dengue virus and promoted the systemic cellular immune responses. This achievement presents the potential of CaP based vaccine biomineralization for the fabrication of needle-free vaccine formulation.

Highly Efficient p-i-n Perovskite Solar Cells Utilizing Novel Low-Temperature Solution-Processed Hole Transport Materials with Linear π-Conjugated Structure.

Alternative low-temperature solution-processed hole-transporting materials (HTMs) without dopant are critical for highly efficient perovskite solar cells (PSCs). Here, two novel small molecule HTMs with linear π-conjugated structure, 4,4'-bis(4-(di-p-toyl)aminostyryl)biphenyl (TPASBP) and 1,4'-bis(4-(di-p-toyl)aminostyryl)benzene (TPASB), are applied as hole-transporting layer (HTL) by low-temperature (sub-100 °C) solution-processed method in p-i-n PSCs. Compared with standard poly(3,4-ethylenedioxythiophene): poly(styrenesulfonic acid) (PEDOT:PSS) HTL, both TPASBP and TPASB HTLs can promote the growth of perovskite (CH3 NH3 PbI3 ) film consisting of large grains and less grain boundaries. Furthermore, the hole extraction at HTL/CH3 NH3 PbI3 interface and the hole transport in HTL are also more efficient under the conditions of using TPASBP or TPASB as HTL. Hence, the photovoltaic performance of the PSCs is dramatically enhanced, leading to the high efficiencies of 17.4% and 17.6% for the PSCs using TPASBP and TPASB as HTL, respectively, which are ≈40% higher than that of the standard PSC using PEDOT:PSS HTL.

The Effects of Improved Photoelectric Properties of PEDOT:PSS by Two-Step Treatments on the Performance of Polymer Solar Cells Based on PTB7-Th:PC(71)BM.

In this paper, we present a smart two-step treated method to simultaneously improve the work function, conductivity, and transmittance of poly(3,4-ethylenedioxythiophene):poly(styrene sulfonate) ( PEDOT: PSS). With the two-step treated PEDOT: PSS, the short-circuit current density of polymer solar cells (PSCs) based on PTB7-Th:PC71BM increases from 13.41 to 22.10 mA/cm(2), and the power conversion efficiency increases from 7.35% to 9.82% with 33% improvement. The underlying mechanisms on performance improvement of PSCs can be summarized as follows: (1) two-step treated PEDOT: PSS with the improved work function and the conductivity, which contributes significantly to the charge collection of PSCs; and (2) two-step treated PEDOT: PSS with higher transmittance, which is of benefit to the light absorption of the active layer in PSCs.

Intracellular delivery of biomineralized monoclonal antibodies to combat viral infection.

Conventional therapeutic monoclonal antibodies (mAbs) are invalid for intracellular viruses but by using in situ biomineralization treatment, they can be successfully delivered into cells to inhibit intracellular viral replication. This achievement significantly expands the applications of mAbs and provides a new intracellular strategy to control viral infections.