Deep silicification-assisted long-term preservation of structural and genomic information across biospecies: From micro to macro.

The concurrent preservation of morphological, structural, and genomic attributes within biological samples is paramount for comprehensive insights into biological phenomena and disease mechanisms. However, current preservation methodologies (e.g., cryopreservation, chemical reagent fixation, and bioplasticization) exhibit limitations in simultaneously achieving these critical combined goals. To address this gap, inspired by natural fossilization, here we propose "deep silicification," a room temperature technology that eliminates fixation requirements and overcomes the cold chain problem. By harnessing the synergy between ethanol and dimethyl sulfoxide, deep silicification significantly enhances silica penetration and accumulation within bioorganisms, thereby reinforcing structural integrity. This versatile and cost-effective approach demonstrates remarkable efficacy in preserving organismal morphology across various scales. Accelerated aging experiments underscore a 4,723-fold enhancement in genomic information storage over millennia, with whole-genome sequencing confirming nearly 100% fidelity. With its simplicity and reliability, "deep silicification" represents a paradigm shift in biological sample storage.

Living to Lithified: Construction and Preservation of Silicified Biomarkers.

Whole microorganisms are rarely preserved in the fossil record but actively silicifying environments like hot springs provide an opportunity for microbial preservation, making silicifying environments critical for the study of microbial life through time on Earth and possibly other planetary bodies. Yet, the changes that biosignatures may undergo through lithification and burial remain unconstrained. At Steep Cone Geyser in Yellowstone National Park, we collected microbial material from (1) the living system across the active outflows, (2) the silicified areas adjacent to flows, and (3) lithified and buried material to assess the preservation of biosignatures and their changes across the lithification transect. Five biofabrics, built predominantly by Cyanobacteria Geitlerinema, Pseudanabaenaceae, and Leptolyngbya with some filamentous anoxygenic phototrophs contributions, were identified and tracked from the living system through the process of silicification/lithification. In the living systems, δ30Si values decrease from +0.13‰ in surficial waters to -2‰ in biomat samples, indicating a kinetic isotope effect potentially induced by increased association with actively growing biofabrics. The fatty acids C16:1 and iso-C14:0 and the hydrocarbon C17:0 were disentangled from confounding signals and determined to be reliable lipid biosignatures for living biofabric builders and tenant microorganisms. Builder and tenant microbial biosignatures were linked to specific Cyanobacteria, anoxygenic phototrophs, and heterotrophs, which are prominent members of the living communities. Upon lithification and burial, silicon isotopes of silicified biomass began to re-equilibrate, increasing from δ30Si -2‰ in living biomats to -0.55‰ in lithified samples. Active endolithic microbial communities were identified in lithified samples and were dominated by Cyanobacteria, heterotrophic bacteria, and fungi. Results indicate that distinct microbial communities build and inhabit silicified biofabrics through time and that microbial biosignatures shift over the course of lithification. These findings improve our understanding of how microbial communities silicify, the biomarkers they retain, and transitionary impacts that may occur through lithification and burial.

Photosystem modulation and extracellular silicification in green microalgae: Key strategies for lead tolerance and removal.

The escalating contamination caused by lead ions (Pb2⁺) and its harmful effects on all life forms has raised global concerns. Certain microalgae thrive in metal mining sites characterized by low pH and high concentrations of Pb2⁺, which are usually prohibitive for many microorganisms. Little is known about the mechanisms underlying the adaptation of such microalgae to these hostile conditions. In this study, we elucidated the adaptive strategies of the green microalga Micractinium belenophorum strain AUMW, isolated from a lead mining site, and its application for the removal of Pb+2. Results revealed that strain AUMW can efficiently tolerate up to 200 ppm of Pb+2 in an F/2 medium. Further experimental variables were optimized through response surface methodology (RSM), and 99.6 % removal of Pb2⁺ was achieved. Novel adaptive responses of strain AUMW to high levels of Pb2⁺ include: (i) activation of metal-protective response by modulation of quantum yield (F v /F m ) and non-photochemical quenching (NPQ) of photosystem II; (ii) extracellular silicification encapsulated cells of strain AUMW and altered cell morphology from oval to hexagonal; (iii) silicification prevented intracellular translocation of Pb+2; (iv) silicification boosted adsorption of Pb+2, thus enhanced its removal. This study offers new insights into the protective role of silicification in green microalgae and its potential for the removal of metals from metal-polluted sites, waste from energy storage battery industries, and spent batteries. It also provides a solid base to explore the genetic and metabolic pathways involved in the adaptation of strain AUMW to elevated levels of Pb+2.

Improving normothermic machine perfusion and blood transfusion through biocompatible blood silicification.

The growing world population and increasing life expectancy are driving the need to improve the quality of blood transfusion, organ transplantation, and preservation. Here, to improve the ability of red blood cells (RBCs) for normothermic machine perfusion, a biocompatible blood silicification approach termed "shielding-augmenting RBC-in-nanoscale amorphous silica (SARNAS)" has been developed. The key to RBC surface engineering and structure augmentation is the precise control of the hydrolysis form of silicic acid to realize stabilization of RBC within conformal nanoscale silica-based exoskeletons. The formed silicified RBCs (Si-RBCs) maintain membrane/structural integrity, normal cellular functions (e.g., metabolism, oxygen-carrying capability), and enhance resistance to external stressors as well as tunable mechanical properties, resulting in nearly 100% RBC cryoprotection. In vivo experiments confirm their excellent biocompatibility. By shielding RBC surface antigens, the Si-RBCs provide universal blood compatibility, the ability for allogeneic mechanical perfusion, and more importantly, the possibility for cross-species transfusion. Being simple, reliable, and easily scalable, the SARNAS strategy holds great promise to revolutionize the use of engineered blood for future clinical applications.

Mineralogical and microbial characterization of alkali hot spring microbial mats and deposits in Pong Dueat Pa Pae hot spring, Northern Thailand.

Hot spring environments encompass broad physicochemical ranges, in which temperature and pH account for crucial factors shaping hot spring microbial community and diversity. However, the presence of photosynthetic microbial mats adjacent to boiling hot spring vents, where fluid temperatures extend beyond photosynthetic capability, questions the microbial profiles and the actual temperatures of such adjacent mats. Therefore, this study aims to characterize thermophilic microbial communities at Pong Dueat Pa Pae hot spring using next-generation sequencing, including investigating hot spring mineralogy. Results suggest that Pong Dueat Pa Pae hot spring precipitates comprise mainly silica which also acts as the main preservative medium for microbial permineralization. Molecular results revealed the presence of cyanobacterial and Chloroflexi species in the thick, orange and green subaerial mats surrounding the vents, suggesting the mats would be at least 30 °C cooler than source vents despite constantly receiving geyser splashes. Bacterial abundance was considerably higher than archaeal (97.9% versus 2.1%). Cyanobacterial (mainly Synechococcus and Leptolygbya) and Chloroflexi species (mainly Roseiflexus) accounted for almost half (40.04%) of the bacterial community, while DHVEG-6 and Thaumarchaeota comprised dominant members (> 90%) of the archaeal fraction. This study updates and provides insights into thermophilic microbial community composition and mineralogy of hot springs in Thailand.

Multivariate Silicification-Assisted Single Enzyme Structure Augmentation for Improved Enzymatic Activity-Stability Trade-Off.

The ability to finely tune/balance the structure and rigidity of enzymes to realize both high enzymatic activity and long-term stability is highly desired but highly challenging. Herein, we propose the concept of the "silicazyme", where solid inorganic silica undergoes controlled hybridization with the fragile enzyme under moderate conditions at the single-enzyme level, thus enabling simultaneous structure augmentation, long-term stability, and high enzymatic activity preservation. A multivariate silicification approach was utilized and occurred around individual enzymes to allow conformal coating. To realize a high activity-stability trade-off the structure flexibility/rigidity of the silicazyme was optimized by a component adjustment ternary (CAT) plot method. Moreover, the multivariate organosilica frameworks bring great advantages, including surface microenvironment adjustability, reversible modification capability, and functional extensibility through the rich chemistry of silica. Overall silicazymes represent a new class of enzymes with promise for catalysis, separations, and nanomedicine.

Rapid Silicification of a DNA Origami with Shape Fidelity.

High-fidelity patterning of DNA origami nanostructures on various interfaces holds great potential for nanoelectronics and nanophotonics. However, distortion of a DNA origami often occurs due to the strong interface interactions, e.g., on two-dimensional (2D) materials. In this study, we discovered that the adsorption of silica precursors in rapid silicification can prevent the distortion caused by graphene and generates a high shape-fidelity DNA origami-silica composite on a graphene interface. We found that an incubation time of 1 min and silicification time of 16 h resulted in the formation of DNA origami-silica composites with the highest shape fidelity of 99%. By comparing the distortion of the DNA origami on the graphene interface with and without silicification, we observed that rapid silicification effectively preserved the integrity of the DNA origami. Statistical analysis of scanning electron microscopy data indicates that compared to bare DNA origami, the DNA origami-silica composite has an increased shape fidelity by more than two folds. Furthermore, molecular dynamics simulations revealed that rapid silicification effectively suppresses the distortion of the DNA origami through the interhelical insertion of silica precursors. Our strategy provides a simple yet effective solution to maintain the shape-fidelity DNA origami on interfaces that have strong interaction with DNA molecules, expanding the applicable interfaces for patterning 2D DNA origamis.

Diatom-inspired silicification process for development of green flexible silica composite aerogels.

In this study, we have developed novel biomimetic silica composite aerogels and cryogels for the first time, drawing inspiration from the natural diatom's silicification process. Our biomimetic approach involved the modification of tyrosinase-mediated oxidized silk fibroin (SFO) surfaces with polyethyleneimine (PEI). This modification introduced ample amine groups onto the SF polymer, which catalyzed the silicification of the SFO-PEI gel surface with silicic acid. This process emulates the catalytic function of long-chain polyamines and silaffin proteins found in diatoms, resulting in a silica network structure on the primary SFO-PEI network gel's surface. The SFO-PEI gel matrix played a dual role in this process: (1) It provided numerous amine functional groups that directly catalyzed the silicification of silicic acid on the porous structure's exterior surface, without encapsulating the created silica network in the gel. (2) It served as a flexible mechanical support facilitating the creation of the silica network. As a result, the final ceramic composite exhibits a mechanically flexible nature (e.g., cyclic compressibility up to 80% strain), distinguishing it from conventional composite aerogels. By mimicking the diatom's silicification process, we were able to simplify the development of silica-polymer composite aerogels. It eliminates the need for surfactants, multi-step procedures involving solvent exchange, and gel washing. Instead, the reaction occurs under mild conditions, streamlining the composite aerogels fabrication process.

Resolving taphonomic and preparation biases in silicified faunas through paired acid residues and X-ray microscopy.

Paired petrography and acid maceration has shown that preferential silicification of shelly faunas can bias recovery based on taxon and body size. Here, silicified fossils from the Upper Ordovician Edinburg Formation, Strasburg Junction, Virginia, USA, were analyzed using X-ray tomographic microscopy (µCT) in conjunction with recovered residues from acid maceration of the same materials to further examine sources of potential bias. Results reveal that very small (<~1 mm) fossils are poorly resolved in µCT when scanning at lower resolutions (~30 µm), underestimating abundance of taxa including ostracods and bryozoans. Acid maceration, meanwhile, fails to recover poorly silicified fossils prone to disarticulation and/or fragmentation during digestion. Tests for patterns of breakage, however, indicate no significant size or taxonomic bias during extraction. Comparisons of individual fossils from 3-D fossil renders and maceration residues reveal patterns of fragmentation that are taxon-specific and allow the differentiation of biostratinomic and preparational breakage. Multivariate ordinations and cluster analyses of µCT and residue data in general produce concordant results but indicate that the variation in taxonomic composition of our samples is compromised by the resolvability of small size classes in µCT imaging, limiting the utility of this method for addressing paleoecological questions in these specific samples. We suggest that comparability of results will depend strongly on the sample size, taphonomic history, textural, and compositional characteristics of the samples in question, as well as µCT scan parameters. Additionally, applying these methods to different deposits will test the general applicability of the conclusions drawn on the relative strengths and weaknesses of the methods.

Siliplant1 B-domain precipitates silica spheres, aggregates, or gel, depending on Si-precursor to peptide ratios.

Silica is extensively deposited by plants, however, only little is known about the molecular control over this process. Siliplant1 is the only known plant protein to precipitate biosilica. The protein contains seven repeats made of three domains. One of the domains exhibits a conserved sequence, which catalyzes silica precipitation in vitro. Here, silica was synthesized by the activity of a peptide carrying this conserved sequence. Infrared spectroscopy and thermal gravimetric analyses showed that the peptide was bound to the mineral. Scanning electron microscopy showed that silica-peptide particles of 22 ± 4 nm aggregated to spherical structures of 200-300 nm when the ratio of silicic acid to the peptide was below 183:1 molecules. When the ratio was about 183:1, similar particles aggregated into irregular structures, and silica gel formed at higher ratios. Solid-state NMR spectra indicated that the irregular aggregates were richer in Si-O-Si bonds as well as disordered peptide. Our results suggest that the peptide catalyzed the condensation of silicic acid and the formation of ∼20 nm particles, which aggregated into spheres. Excess of the peptide stabilized surface Si-OH groups that prevented spontaneous Si-O-Si bonding between aggregates. Under Si concentrations relevant to plant sap, the peptide and possibly Siliplant1, could catalyze nucleation of silica particles that aggregate into spherical aggregates.

The compact genome of the sponge Oopsacas minuta (Hexactinellida) is lacking key metazoan core genes.

BACKGROUND: Explaining the emergence of the hallmarks of bilaterians is a central focus of evolutionary developmental biology-evodevo-and evolutionary genomics. For this purpose, we must both expand and also refine our knowledge of non-bilaterian genomes, especially by studying early branching animals, in particular those in the metazoan phylum Porifera. RESULTS: We present a comprehensive analysis of the first whole genome of a glass sponge, Oopsacas minuta, a member of the Hexactinellida. Studying this class of sponge is evolutionary relevant because it differs from the three other Porifera classes in terms of development, tissue organization, ecology, and physiology. Although O. minuta does not exhibit drastic body simplifications, its genome is among the smallest of animal genomes sequenced so far, and surprisingly lacks several metazoan core genes (including Wnt and several key transcription factors). Our study also provides the complete genome of a symbiotic Archaea dominating the associated microbial community: a new Thaumarchaeota species. CONCLUSIONS: The genome of the glass sponge O. minuta differs from all other available sponge genomes by its compactness and smaller number of encoded proteins. The unexpected loss of numerous genes previously considered ancestral and pivotal for metazoan morphogenetic processes most likely reflects the peculiar syncytial tissue organization in this group. Our work further documents the importance of convergence during animal evolution, with multiple convergent evolution of septate-like junctions, electrical-signaling and multiciliated cells in metazoans.

Spatial and temporal dynamics at an actively silicifying hydrothermal system.

Steep Cone Geyser is a unique geothermal feature in Yellowstone National Park (YNP), Wyoming, actively gushing silicon-rich fluids along outflow channels possessing living and actively silicifying microbial biomats. To assess the geomicrobial dynamics occurring temporally and spatially at Steep Cone, samples were collected at discrete locations along one of Steep Cone's outflow channels for both microbial community composition and aqueous geochemistry analysis during field campaigns in 2010, 2018, 2019, and 2020. Geochemical analysis characterized Steep Cone as an oligotrophic, surface boiling, silicious, alkaline-chloride thermal feature with consistent dissolved inorganic carbon and total sulfur concentrations down the outflow channel ranging from 4.59 ± 0.11 to 4.26 ± 0.07 mM and 189.7 ± 7.2 to 204.7 ± 3.55 µM, respectively. Furthermore, geochemistry remained relatively stable temporally with consistently detectable analytes displaying a relative standard deviation <32%. A thermal gradient decrease of ~55°C was observed from the sampled hydrothermal source to the end of the sampled outflow transect (90.34°C ± 3.38 to 35.06°C ± 7.24). The thermal gradient led to temperature-driven divergence and stratification of the microbial community along the outflow channel. The hyperthermophile Thermocrinis dominates the hydrothermal source biofilm community, and the thermophiles Meiothermus and Leptococcus dominate along the outflow before finally giving way to more diverse and even microbial communities at the end of the transect. Beyond the hydrothermal source, phototrophic taxa such as Leptococcus, Chloroflexus, and Chloracidobacterium act as primary producers for the system, supporting heterotrophic growth of taxa such as Raineya, Tepidimonas, and Meiothermus. Community dynamics illustrate large changes yearly driven by abundance shifts of the dominant taxa in the system. Results indicate Steep Cone possesses dynamic outflow microbial communities despite stable geochemistry. These findings improve our understanding of thermal geomicrobiological dynamics and inform how we can interpret the silicified rock record.

Regulation of thermodynamics and kinetics of silica nucleation during the silicification process in higher plants.

The formation mechanism of SiO2 aggregates is controversial because two contrasting hypotheses are often proposed to explain plant silicification. In this review, we summarize the physicochemical fundamentals of amorphous silica nucleation and discuss how plants regulate the process of silicification by influencing the thermodynamics and kinetics of silica nucleation. At silicification positions, plants overcome the thermodynamic barrier by establishing the supersaturation of the H4SiO4 solution and reducing the interfacial free energy. Among the thermodynamic-drivers, the establishment of supersaturation of H4SiO4 solution mainly depends on the expression of Si transporters for H4SiO4 supply, evapotranspiration for concentrating Si, and the other solutes in H4SiO4 solution for influencing the dissolution equilibrium of SiO2; while the interfacial free energy was reduced seemingly by the overexpression Na+/H+ antiporter SOS1 in high NaCl-stressed rice. Moreover, some kinetic-drivers, such as silicification-related proteins (Slp1 and PRP1) and new cell wall components, are actively expressed or synthesized by plants to interact with silicic acid, thereby reducing the kinetic barrier. According to classical nucleation theory, when the thermodynamic barrier is overcome, the super-saturated silicic acid solution (such as H4SiO4 in xylem sap) does not necessarily have to precipitate, just has the potential ability to precipitation. Thus, based on the mediators of SiO2 deposition at the thermodynamic-driven stage, it is difficult to evaluate whether the process of plant silicification is active or passive. We conclude that the characteristics of kinetic-drivers determine the mechanism of plant silicification.

Polymer-Rich Dense Phase Can Concentrate Metastable Silica Precursors and Regulate Their Mineralization.

Multistep mineralization processes are pivotal in the fabrication of functional materials and are often characterized by far from equilibrium conditions and high supersaturation. Interestingly, such 'nonclassical' mineralization pathways are widespread in biological systems, even though concentrating molecules well beyond their saturation level is incompatible with cellular homeostasis. Here, we show how polymer phase separation can facilitate bioinspired silica formation by passively concentrating the inorganic building blocks within the polymer dense phase. The high affinity of the dense phase to mobile silica precursors generates a diffusive flux against the concentration gradient, similar to dynamic equilibrium, and the resulting high supersaturation leads to precipitation of insoluble silica. Manipulating the chemistry of the dense phase allows to control the delicate interplay between polymer chemistry and silica precipitation. These results connect two phase transition phenomena, mineralization and coacervation, and offer a framework to achieve better control of mineral formation.

Green synthesis of silica-coated magnetic nanocarriers for simultaneous purification-immobilization of ß-1,3-xylanase.

Tailoring magnetic nanocarriers with tunable properties is of great significance for the development of multifunctional candidate materials in numerous fields. Herein, we report a one-pot biomimetic silicification-based method for the synthesis of silica-coated magnetic nanoparticles. The synthesis process was mild, low cost, and highly efficient, which took only about 21 min compared with 4.5-120 h in other literature. Then, the carriers had been characterized by VSM, SEM, TEM, XRD, FT-IR, and EDS to confirm their function. To evaluate the usefulness of the carriers, they were adopted to couple the purification and immobilization of ß-1,3-xylanase from the cell lysate in a single step with high immobilization yield (92.8 %) and high activity recovery (82.4 %). The immobilized enzyme also retained 58.4 % of the initial activity after 10 cycles and displayed good storage properties, and improved thermal stability, which would be promising in algae biomass bioconversion as well as other diverse applications.

Designing sequence-defined peptoids for fibrillar self-assembly and silicification.

In the biological environment, mineral crystals exquisitely controlled by biomacromolecules often show intricate hierarchical structures and superior mechanical properties. Among these biominerals, spicules, hybrid silica/protein superstructures serving as skeletal elements in demosponges, represent an excellent example for motivating the synthesis of silica materials. Herein, by designing sequence-defined peptoids containing side chains with a strong binding to silica, we demonstrated that self-assembly of these peptoids into fiber structures enables the mimicking of both biocatalytic and templating functions of silicatein filaments for the formation of silica fibers at near-neutral pH and ambient temperature. We further showed that the presence of amino groups is significant for the nucleation of silica on self-assembled peptoid nanofibers. Molecular dynamics simulation further confirmed that having silica-binding of amino side chains is critical for self-assembled peptoid fibers in triggering silica formation. We demonstrated that tuning inter-peptoid interactions by varying carboxyl and amino side chains significantly influences the assembly kinetics and final morphologies of peptoid assemblies as scaffolds for directing silica mineralization to form silica spheres, fibers, and sheets. The formation of silica shell on peptoid fibers increased the mechanical property of peptoid hydrogel materials by nearly 1000-fold, highlighting the great potential of using silicification to enhance the mechanical property of hydrogel materials for applications including tissue engineering. Since peptoids are highly robust and programmable, we expect that self-assembly of peptoids containing solid-binding side chains into hierarchical materials opens new opportunities in the design and synthesis of highly tunable scaffolds that direct the formation of composite nanomaterials.

Revealing the role of tunable amino acid residues in elastin-like polypeptides (ELPs)-mediated biomimetic silicification.

Elastin-like polypeptides (ELPs) are attractive materials for the green preparation of silica nanoparticles via biomimetic silicification. However, the critical factors affecting the ELP-mediated silicification remain unclear. Herein, the role of tunable amino acid residues of ELPs in silicification was studied using three ELPs (ELPs[V9F-40], ELPs[KV8F-40], and ELPs[K5V4F-40]) and their fusion proteins (ELPs[V9F-40]-SpyCatcher, ELPs[KV8F-40]-SpyCatcher, and ELPs[K5V4F-40]-SpyCatcher) with different contents of lysine residues. Bioinformatics methods were employed for the first time to reveal the key physicochemical parameters correlated with silicification. The specific activity of ELPs was increased with the promotion of lysine content with a high correlation coefficient (R = 0.899). Furthermore, exogenous acidic protein SpyCatcher would hinder the interactions between the silica precursors and ELPs, leading to the significantly decrease in specific activity. The isoelectric point (pI) of ELPs presented the highest correlation to silicification with a coefficient of 0.963. The charges of the ELPs [K5V4F-40] at different pH were calculated based on the sequence or structure. Interestingly, the excellent correlation between charges based on structure and specific activity was obtained. Collectively, the novel methods developed here may pave a new way for rational design of ELPs or other peptides for efficient and green preparation of silica nanomaterials for biomedicine, biocatalysis, and biosensor.

Why do plants silicify?

Despite seminal papers that stress the significance of silicon (Si) in plant biology and ecology, most studies focus on manipulations of Si supply and mitigation of stresses. The ecological significance of Si varies with different levels of biological organization, and remains hard to capture. We show that the costs of Si accumulation are greater than is currently acknowledged, and discuss potential links between Si and fitness components (growth, survival, reproduction), environment, and ecosystem functioning. We suggest that Si is more important in trait-based ecology than is currently recognized. Si potentially plays a significant role in many aspects of plant ecology, but knowledge gaps prevent us from understanding its possible contribution to the success of some clades and the expansion of specific biomes.

BMP2-Mediated Silica Deposition: An Effective Strategy for Bone Mineralization.

The combined use of an osteogenic factor, such as bone morphogenetic protein 2 (BMP2), with a bone scaffold was quite functional for the reconstruction of bone defects. Although many studies using BMP2 have been done, there is still a need to develop an efficient way to apply BMP2 in the bone scaffold. Here, we reported an interesting fact that BMP2 has a silica deposition ability in the presence of silicic acid and proposed that such an ability of BMP2 can effectively immobilize and transport itself by a kind of coprecipitation of BMP2 with a silica matrix. The presence of BMP2 in the resulting silica was proved by SEM and EDS and was visualized by FITC-labeled BMP2. The delivery efficacy of BMP2 of silica-entrapped BMP2 on osteoblast differentiation and mineralization using MC3T3 E1 preosteoblast cells was evaluated in vitro. The coprecipitated BMP2 with silica exhibited osteogenesis at a low concentration that was insufficient to give an osteoinductive signal as the free form. Expectedly, the silica-entrapped BMP2 exhibited thermal stability over free BMP2. When applied to bone graft substitution, e.g., hydroxyapatite granules (HA), silica-entrapped BMP 2 laden HA (BMP2@Si/HA) showed sustained BMP2 release, whereas free BMP2 adsorbed HA by a simple dipping method (BMP2/HA) displayed a burst release of BMP2 at an initial time. In the rat critical-size calvarial defect model, BMP2@Si/HA showed better bone regeneration than BMP2/HA by about 10%. The BMP2/silica hybrid deposited on a carrier surface via BMP2-mediated silica precipitation demonstrated an increase in the loading efficiency, a decrease in the burst release of BMP2, and an increase in bone regeneration. Taken together, the coprecipitated BMP2 with a silica matrix has the advantages of not only being able to immobilize BMP2 efficiently without compromising its function but also serving as a stable carrier for BMP2 delivery.

Thalassiosira weissflogii grown in various Zn levels shows different ecophysiological responses to seawater acidification.

The presence of zinc (Zn), a vital element for algal physiological functions, coupled with the silicification of diatoms implies that it plays an integral role in the carbon and silicon cycles of the sea. In this study, we examined the effects of different pCO2 and Zn levels on growth rate, elemental compositions and silicification by Thalassiosira weissflogii. The results showed that under normal pCO2 (400 µatm), cultures of T. weissflogii were depressed for growth rate and silica incorporation rate, but encouraged for cellular silicon content, Si/C, Si/N, and sinking rate when Zn deficient (0.3 pmol L-1). However, cellular silicon and sinking rate of Zn-deficient and Zn-replete (25 pmol L-1) T. weissflogii were decreased and increased at higher pCO2 (800 µatm), respectively. Thus, acidification may affect diatoms significantly differently depending on the Zn levels of the ocean and then alter the biochemical cycling of carbon and silica.