Promoting effect of phosvitin in the mineralization of eggshell inner membrane with the application in osteogenic induction scaffold

Exploring affordable and easily prepared inorganic-organic hybrid membrane materials has attracted a great interest in the bone repair field. This study is based on biomimetic mineralization technique to study the role of phosvitin (PV) in the mineralized process of eggshell inner membrane. Results showed that PV promoted the formation of hydroxyapatite on the eggshell inner membrane surface, and the phosvitin content in the simulated body fluid was decreased during the mineralization process. Besides, in vitro preosteoblast experiments indicated that mineralized membrane with PV exhibited more conducive to cell proliferation and differentiation than that mineralized membrane without PV. Interestingly, with the increase of mineralization time, the stimulating ability of mineralized membranes with PV on adhesion, proliferation, alkaline phosphatase activity and collagen type I content gradually improved. In summary, the eggshell inner membrane composites mineralized with PV obtained by biomimetic mineralization might be potential scaffold materials for bone repair.

A one-two punch strategy for diabetic wound management based on an antibiotic-hybrid biomineralized iron sulfide nanoparticle

Bacterial infection and immune imbalance are the primary culprits behind chronic wounds in individuals with diabetes, impeding the progression of damaged tissues towards normal healing. To achieve a harmonious balance between pro- and anti-inflammation within these infected areas, herein, we propose a one-two punch strategy for on-demand therapy of diabetes-infected wounds, utilizing an azithromycin (AZM)-hybrid nanocomposite termed GOx@FexSy/AZM. During the infective stage, the nanocomposite facilitates the production of ROS, coupled with the burst release of AZM and H2S gas, effectively dismantling biofilms and achieving rapid sterilization. Subsequently, the hyperinflammatory response induced by antibiosis is significantly mitigated through the synergistic action of tissue H2S and the prolonged half-life of AZM. These components inhibit the activity of pro-inflammatory transcription factors (AP-1 and NF-κB) within macrophages, thereby promoting the polarization of macrophages towards a reparative M2 phenotype and facilitating tissue remodeling. By catering to the diverse requirements of wound healing at different stages, this nanocomposite accelerates a sensible transition from inflammation to the reparative phase. In summary, this one-two punch strategy gives an instructive instance for procedural treatment of diabetes wound infection. STATEMENT OF SIGNIFICANCE: The treatment of diabetic wound infection presents two major challenges: the diminished antibacterial efficacy arising from biofilm formation and bacterial resistance, as well as the inadequate transition of the wound microenvironment from pro-inflammatory to anti-inflammatory states after bacterial clearance. In this work, a biomineralized iron sulfide nanocomposite was prepared to mediate cascade catalytic (ROS storm) / antibiotic (AZM) / gas (H2S) triple-synergetic antibacterial therapy during the initial stage of bacterial infection, achieving the goal of rapid bactericidal effect; Subsequently, the residual H2S and long half-life AZM would inhibit the key pro-inflammatory transcription factors and promote the macrophages polarization to reparative M2, which effectively mediated tissue repair after hyperinflammatory reactions, leading to orderly treatment of hyperglycemic infected wounds.

Biomimetic Mineralized 3D-Printed Polycaprolactone Scaffold Induced by Self-Adaptive Nanotopology to Accelerate Bone Regeneration

Three-dimensional (3D)-printed biodegradable polymer scaffolds are at the forefront of personalized constructs for bone tissue engineering. However, it remains challenging to create a biological microenvironment for bone growth. Herein, we developed a novel yet feasible approach to facilitate biomimetic mineralization via self-adaptive nanotopography, which overcomes difficulties in the surface biofunctionalization of 3D-printed polycaprolactone (PCL) scaffolds. The building blocks of self-adaptive nanotopography were PCL lamellae that formed on the 3D-printed PCL scaffold via surface-directed epitaxial crystallization and acted as a linker to nucleate and generate hydroxyapatite crystals. Accordingly, a uniform and robust mineralized layer was immobilized throughout the scaffolds, which strongly bound to the strands and had no effect on the mechanical properties of the scaffolds. In vitro cell culture experiments revealed that the resulting scaffold was biocompatible and enhanced the proliferation and osteogenic differentiation of mouse embryolous osteoblast cells. Furthermore, we demonstrated that the resulting scaffold showed a strong capability to accelerate in vivo bone regeneration using a rabbit bone defect model. This study provides valuable opportunities to enhance the application of 3D-printed scaffolds in bone repair, paving the way for translation to other orthopedic implants.

A novel mussel-inspired desensitizer based on radial mesoporous bioactive nanoglass for the treatment of dentin exposure: An in vitro study

OBJECTIVES

The dentin exposure always leads to dentin hypersensitivity and the acid-resistant/abrasion-resistant stability of current therapeutic approaches remain unsatisfatory. Inspired by the excellent self-polymerization/adherence activity of mussels and the superior mineralization ability of bioactive glass, a novel radial mesoporous bioactive nanoglass coated with polydopamine (RMBG@PDA) was developed for prevention and management of dentin hypersensitivity.

METHODS

Radial mesoporous bioactive nanoglass (RMBG) was synthesized by the sol-gel process combined with the cetylpyridine bromide template self-assembly technique. RMBG@PDA was synthesized by a self-polymerization process involving dopamine and RMBG in an alkaline environment. Then, the nanoscale morphology, chemical structure, crystalline phase and Zeta potential of RMBG and RMBG@PDA were characterized. Subsequently, the ion release ability, bioactivity, and cytotoxicity of RMBG and RMBG@PDA in vitro were investigated. Moreover, an in vitro experimental model of dentin hypersensitivity was constructed to evaluate the effectiveness of RMBG@PDA on dentinal tubule occlusion, including resistances against acid and abrasion. Finally, the Young's modulus and nanohardness of acid-etched dentin were also detected after RMBG@PDA treatment.

RESULTS

RMBG@PDA showed a typical nanoscale morphology and noncrystalline structure. The use of RMBG@PDA on the dentin surface could effectively occlude dentinal tubules, reduce dentin permeability and achieve excellent acid- and abrasion-resistant stability. Furthermore, RMBG@PDA with excellent cytocompatibility held the capability to recover the Young's modulus and nanohardness of acid-etched dentin.

CONCLUSION

The application of RMBG@PDA with superior dentin tubule occlusion ability and acid/abrasion-resistant stability can provide a therapeutic strategy for the prevention and the management of dentin hypersensitivity.

Bioinspired mp20 mimicking uricase in ZIF-8: Metal ion dependent for controllable activity

Mini protein mimicking uricase (mp20) has shown significant potential as a replacement for natural enzymes in the development of uric acid biosensors. However, the design of mp20 has resulted to an inactive form of peptide, causing of loss their catalytic activity. Herein, this paper delineates the impact of various metal cofactors on the catalytic activity of mp20. The metal ion-binding site prediction and docking (MIB) web server was employed to identify the metal ion binding sites and their affinities towards mp20 residues. Among the tested metal ions, Cu2+ displayed the highest docking score, indicating its preference for interaction with Thr16 and Asp17 residues of mp20. To assess the catalytic activity of mp20 in the presence of metal ions, uric acid assays was monitored using a colorimetric method. The presence of Cu2+ in the assays promotes the activation of mp20, resulting in a color change based on quinoid production. Furthermore, the encapsulation of the mp20 within zeolitic imidazolate framework-8 (ZIF-8) notably improved the stability of the biomolecule. In comparison to the naked mp20, the encapsulated ZIFs biocomposite (mp20@ZIF-8) demonstrates superior stability, selectivity and sensitivity. ZIF's porous shells provides excellent protection, broad detection (3-100 μM) with a low limit (4.4 μM), and optimal function across pH (3.4-11.4) and temperature (20-100°C) ranges. Cost-effective and stable mp20@ZIF-8 surpasses native uricase, marking a significant biosensor technology breakthrough. This integration of metal cofactor optimization and robust encapsulation sets new standards for biosensing applications.

3D-printed PCL framework assembling ECM-inspired multi-layer mineralized GO-Col-HAp microscaffold for in situ mandibular bone regeneration

BACKGROUND

In recent years, natural bone extracellular matrix (ECM)-inspired materials have found widespread application as scaffolds for bone tissue engineering. However, the challenge of creating scaffolds that mimic natural bone ECM's mechanical strength and hierarchical nano-micro-macro structures remains. The purposes of this study were to introduce an innovative bone ECM-inspired scaffold that integrates a 3D-printed framework with hydroxyapatite (HAp) mineralized graphene oxide-collagen (GO-Col) microscaffolds and find its application in the repair of mandibular bone defects.

METHODS

Initially, a 3D-printed polycaprolactone (PCL) scaffold was designed with cubic disks and square pores to mimic the macrostructure of bone ECM. Subsequently, we developed multi-layer mineralized GO-Col-HAp microscaffolds (MLM GCH) to simulate natural bone ECM's nano- and microstructural features. Systematic in vitro and in vivo experiments were introduced to evaluate the ECM-inspired structure of the scaffold and to explore its effect on cell proliferation and its ability to repair rat bone defects.

RESULTS

The resultant MLM GCH/PCL composite scaffolds exhibited robust mechanical strength and ample assembly space. Moreover, the ECM-inspired MLM GCH microscaffolds displayed favorable attributes such as water absorption and retention and demonstrated promising cell adsorption, proliferation, and osteogenic differentiation in vitro. The MLM GCH/PCL composite scaffolds exhibited successful bone regeneration within mandibular bone defects in vivo.

CONCLUSIONS

This study presents a well-conceived strategy for fabricating ECM-inspired scaffolds by integrating 3D-printed PCL frameworks with multilayer mineralized porous microscaffolds, enhancing cell proliferation, osteogenic differentiation, and bone regeneration. This construction approach holds the potential for extension to various other biomaterial types.

[Effects of different polymers on biomimetic mineralization of small intestine submucosal scaffolds]

OBJECTIVE

To explore the effects of different polymers on in vitro biomimetic mineralization of small intestinal submucosa (SIS) scaffolds, and to evaluate the physicochemical properties and biocompatibility of the SIS scaffolds.

METHODS

The SIS scaffolds prepared by freeze-drying method were immersed in simulated body fluid (SBF), mineralized liquid containing polyacrylic acid (PAA) and mine-ralized liquid containing PAA and polyaspartic acid (PASP). After two weeks in the mineralized solution, the liquid was changed every other day. SBF@SIS, PAA@SIS, PAA/PASP@SIS scaffolds were obtained. The SIS scaffolds were used as control group to evaluate their physicochemical properties and biocompatibility. We observed the bulk morphology of the scaffolds in each group, analyzed the microscopic morphology by environment scanning electron microscopy and determined the porosity and pore size. We also analyzed the surface elements by energy dispersive X-ray spectroscopy (EDX), analyzed the structure of functional groups by Flourier transformed infrared spectroscopy (FTIR), detected the water absorption rate by using specific gravity method, and evaluated the compression strength by universal mechanical testing machine. The pro-cell proliferation effect of each group of scaffolds were evaluated by CCK-8 cell proliferation method.

RESULTS

Under scanning electron microscopy, the scaffolds of each group showed a three-dimensional porous structure with suitable pore size and porosity, and crystal was observed in all the mineralized scaffolds of each group, in which the crystal deposition of PAA/PASP@SIS scaffolds was more regular. At the same time, the collagen fibers could be seen to thicken. EDX analysis showed that the characteristic peaks of Ca and P were found in the three groups of mineralized scaffolds, and the highest peaks were found in the PAA/PASP@SIS scaffolds. FTIR analysis proved that all the three groups of mineralized scaffolds were able to combine hydroxyapatite with SIS. All the scaffolds had good hydrophilicity. The compressive strength of the mineralized scaffold in the three groups was higher than that in the control group, and the best compressive strength was found in PAA/PASP@SIS scaffold. The scaffolds of all the groups could effectively adsorb proteins, and PAA/PASP@SIS group had the best adsorption capacity. In the CCK-8 cell proliferation experiment, the PAA/PASP@SIS scaffold showed the best ability to promote cell proliferation with the largest number of living cells observed.

CONCLUSION

Compared with other mineralized scaffolds, PAA/PASP@SIS scaffolds prepared by mineralized solution containing both PAA and PASP have better physicochemical properties and biocompatibility and have potential applications in bone tissue engineering.

Facile preparation of biomimetic mineralized COFs based on magnetic silk fibroin and its effective extraction of sulforaphane from cruciferous vegetables

A novel biomimetic mineralized covalent organic framework (BM-COF) was prepared based on magnetic silk fibroin and a new sulforaphane pretreatment technology was constructed. First, metal coordination was performed on the surface of silk fibroin, and nanoparticles were deposited by in-situ mineralization after co-precipitation. Then, biomineralized COFs were prepared by in-situ self-assembly of a COF layer on Fe3O4@silk fibroin surface guided by interfacial directional growth technology. The BM-COFs had a multilayer structure, large specific surface area and pore volume, and superparamagnetic properties, which make them an ideal adsorbent. The adsorption of sulforaphane by BM-COFs is mainly multi-molecular layer adsorption and chemisorption, there might be electrostatic action, π-stacking and hydrogen bonding in the adsorption process. The composite material was successfully used for the pretreatment of sulforaphane in cruciferous vegetables. An extraction time of 30 min gave extraction efficiencies as high as 92%, and the recovery could reach more than 73%.

Biomimetic mineralization-based In situ growth of AuNCs@ZIF-8 on paper fibers for visual detection of copper ions

As one of the essential trace elements in life activities, copper ion (Cu2+) plays a very important role in human health. However, copper-containing pesticides are usually used for sterilization and disinfestation in agriculture. Thus, the residues of copper-containing pesticides in agricultural samples increase the risk of excessive intake of Cu2+ for human. The development of an effective method for detecting Cu2+ is still an important task. Herein, a detecting system based on AuNCs@ZIF-8 modified paper and smartphone platform was developed for visual detection of Cu2+ in agricultural samples. Herein, a detecting system based on AuNCs@ZIF-8 modified paper and smartphone platform was developed for visual detection of Cu2+ in agricultural samples. In the detecting system, gold nanoclusters (AuNCs) were packaged by ZIF-8 to limit their molecular motion and enhance the fluorescence effectively. In the meanwhile, by ultrasound-assisted biomimetic mineralizing, AuNCs@ZIF-8 composites were uniformly synthesized in situ on the surface of the paper fibers to indicate Cu2+ by fluorescence quenching. A portable visual monitoring system consisted of the prepared Cu2+ paper sensor and a smartphone platform was then successfully built and applied to on site detecting Cu2+ in agricultural samples. The limit of detection (LOD) was 4.57 μM and recovery rate varied from 96.50 % to 121.58 %. The developed detecting system for Cu2+ has the advantages of easy preparation and operation, and is very suitable for the use in agricultural products and farmland.

Integrating metal-organic framework ZIF-8 with green modifier empowered bacteria with improved bioremediation

Suspended microorganisms often experience diminished efficacy in the bioremediation of polycyclic aromatic hydrocarbons (PAHs). In this study, the potential of zeolite imidazolate framework-8 (ZIF-8) and the eco-friendly modifier citric acid (CA) was harnessed to generate a biomimetic mineralized protective shell on the surface of Bacillus subtilis ZL09-26, resulting in an enhanced capability for PAH degradation. This investigation encompassed the integrated responses of B. subtilis ZL09-26 to ZIF-8 and ZIF-8-CA at both cellular and proteomic levels. The amalgamation of ZIF-8 and CA not only stimulated the growth and bolstered the cell viability of B. subtilis ZL09-26, but also counteracted the toxic effects of phenanthrene (PHE) stress. Remarkably, the bioremediation prowess of B. subtilis ZL09-26@ZIF-8-CA surpassed that of ZL09-26@ZIF-8 and ZL09-26, achieving a PHE removal rate of 94.14 % within 6 days. After undergoing five cycles, ZL09-26@ZIF-8-CA demonstrated an enduring PHE removal rate exceeding 83.31 %. A complex interplay of various metabolic pathways orchestrated cellular responses, enhancing PHE transport and degradation. These pathways encompassed direct PHE biodegradation, central carbon metabolism, oxidative phosphorylation, purine metabolism, and aminoacyl-tRNA biosynthesis. This study not only extends the potential applications of biomineralized organisms but also offers alternative strategies for effective contaminant management.

Biomimetic mineralization by confined diffusion with viscous hyaluronan network: Assembly of hierarchical flower-like supraparticles

Biomolecules-mediated biomimetic mineralization has been extensively investigated and applied to fabricate nano-assemblies with unique hierarchical architectures and salient properties. The confined-source ion diffusion plays a key role in the biomineralization process, but little investigative efforts have focused on it. Here, we developed a simple method to mimic the in vivo condition by a confined diffusion method, and hydroxyapatite nanoflower assemblies (HNAs) with exquisite hierarchical architectures were obtained. The HNAs were assembled from needle-like hybrid nanocrystals of hydroxyapatite and hyaluronan. The results revealed that the strong interactions between ions and hyaluronan led to the nucleation of hydroxyapatite and the following aggregation. The combination of the external diffusion field and the internal multiple interactions induced the self-assembling processes. Additionally, HNAs with colloid stability and excellent biocompatibility were proved to be a promising cargo carrier for intranuclear delivery. This work presents a novel biomimetic mineralization strategy based on confined diffusion system for fabricating delicate hydroxyapatite, which offers a new perspective for the development of biomimetic strategies.

ZIF-8 induced hydroxyapatite-like crystals enabled superior osteogenic ability of MEW printing PCL scaffolds

ZIF-8 may experience ion-responsive degradation in ionic solutions, which will change its initial architecture and restrict its direct biological use. Herein, we report an abnormal phenomenon in which ZIF-8 induces large hydroxyapatite-like crystals when soaked directly in simulated body fluid. These crystals grew rapidly continuously for two weeks, with the volume increasing by over 10 folds. According to Zn2+ release and novel XRD diffraction peak presence, ZIF-8 particles can probably show gradual collapse and became congregate through re-nucleation and competitive coordination. The phenomenon could be found on ZIF-8/PCL composite surface and printed ZIF-8/PCL scaffold surface. ZIF-8 enhanced PCL roughness through changing the surface topography, while obviously improving the in-vivo and in-vitro osteoinductivity and biocompatibility. The pro-biomineralization property can make ZIF-8 also applicable in polylactic acid-based biomaterials. In summary, this study demonstrates that ZIF-8 may play the role of a bioactive additive enabling the surface modification of synthetic polymers, indicating that it can be applied in in-situ bone regeneration.

Mineralization promotion and protection effect of carboxymethyl chitosan biomodification in biomimetic mineralization

Biomimetic mineralization emphasizes reversing the process of dental caries through bio-inspired strategies, in which mineralization promotion and collagen protection are equally important. In this study, carboxymethyl chitosan (CMC) was deemed as an analog of glycosaminoglycan for biomimetic modification of collagen, both of the mineralization facilitation and collagen protection effect were evaluated. Experiments were carried out simultaneously on two-dimensional monolayer reconstituted collagen model, three-dimensional reconstituted collagen model and demineralized dentin model. In three models, CMC was successfully cross-linked onto collagen utilizing biocompatible 1-Ethyl-3(3-dimethylaminopropyl) carbodiimide hydrochloride and N-hydroxy sulfosuccinimide sodium salt to achieve biomodification. Results showed that CMC biomodification increased collagen's hydrophilicity, calcium absorption capacity and thermal degradation resistance. In demineralized dentin model, the activity of endogenous matrix metalloproteinases was significantly inhibited by CMC biomodification. Furthermore, CMC biomodification significantly improved cross-linking and intrafibrillar mineralization of collagen, especially in the two-dimensional monolayer reconstituted collagen model. This study provided a biomimetic mineralization strategy with comprehensive consideration of collagen protection, and enriched the application of chitosan-based materials in dentistry.

Conformational changes and location of BSA upon immobilization on zeolitic imidazolate frameworks

The location and the conformational changes of proteins/enzymes immobilized within Metal Organic Frameworks (MOFs) are still poorly investigated and understood. Bovine serum albumin (BSA), used as a model protein, was immobilized within two different zeolitic imidazolate frameworks (ZIF-zni and ZIF-8). Pristine ZIFs and BSA@ZIFs were characterized by X-ray diffraction, small-angle X-ray scattering, scanning electron microscopy, confocal laser scanning microscopy, thermogravimetric analysis, micro-FTIR and confocal Raman spectroscopy to characterize MOFs structure and the protein location in the materials. Moreover, the secondary structure and conformation changes of BSA after immobilization on both ZIFs were studied with FTIR. BSA is located both in the inner and on the outer surface of MOFs, forming domains that span from the micro- to the nanoscale. BSA crystallinity (β-sheets + α-helices) increases up to 25 % and 40 % due to immobilization within ZIF-zni and ZIF-8, respectively, with a consequent reduction of β-turns.

Biomimetic one-pot preparation of surface biofunctionalized silica-coated magnetic composites for dual enzyme oriented immobilization without pre-purification

Surface functioned magnetic silica particles are efficient carriers to achieve facilitated separation and recycling of biocatalysts. However, traditional methods of modifying magnetic silica particles required time-costly sequential coating and surface modification steps and toxic solvents. Herein, a green and efficient routine was proposed to prepare the surface modified silica-coated magnetic microspheres (SCEs@SiO₂ @Fe₃O₄) in one-pot. The elastin-like polypeptides (ELPs)-SpyCatcher chimera (SCEs) were purified by inverse transition cycling with high yield (275 mg/L) and incorporated into the magnetic silica spheres based on the biomimetic silicification capability of ELPs as proved by the EDS and SEM mapping. No SCEs leaked was observed within 48 h, indicating excellent stability in buffer. Then, the biofunctionalized carriers were used to purify and immobilize the target dual enzymes (xylanase-linker-SpyTag-linker-lichenase, bienzymes) directly from the crude cell lysis solution by the spontaneous isopeptide bond reaction between SpyCatcher and SpyTag. The immobilized bienzymes were sphere-like magnetic silica particles with uniform size, which had good magnetic responsiveness. The immobilization yield, immobilization efficiency and activity recovery for xylanase were 86%, 84 % and 72 %, while for lichenase was 92 %, 86 % and 79 %, respectively. Besides, the immobilized bienzymes showed good reusability (>60 %, 10 times for xylanase, >95 %, 8 times for lichenase). The SCEs modified silica-coated magnetic microspheres are expected to provide versatile platforms for single-step of purification and immobilization of multienzymes, offering great potentials in the field of biocatalysis.

Engineering a thermostable biosensor based on biomimetic mineralization HRP@Fe-MOF for Alzheimer's disease

The development of disease detection by biosensors represents one of the key components of medical science. However, millions of people are still misdiagnosed each year due to the poor efficacy and thermal instability of biosensors. Using horseradish peroxidase (HRP) as a paradigm, we offer a rational design strategy to optimize the thermostability and activity of biosensors by biomimetic mineralization. To overcome the weak thermostability of the biosensor, the mineralization of Fe-MOF forms an armor on HRP that protects against high temperature. Additionally, the biomimetic mineralization HRP@Fe-MOF can double-catalyze the TMB/H₂O₂ chromogenic system for color development. The biosensor can also be recycled through simple heat treatment due to the thermally stable aptamer and biomimetic mineralization HRP@Fe-MOF. The optical biosensor based on this sensitive spectral transformation was successfully developed for the measurement of AβO with an outstanding linear range (0.0001-10 nM) and a low limit of detection (LOD) of 0.03 pM. This promising platform will open up new avenues for the detection of AβO in the early diagnosis of Alzheimer's disease (AD).

Chitosan-regulated biomimetic hybrid nanoflower for efficiently immobilizing enzymes to enhance stability and by-product tolerance

Organic-inorganic hybrid nano-materials have been considered to be promising immobilization matrixes for enzymes due to their significantly enhanced reusability and stability of enzymes. Herein, we constructed a novel organic-inorganic hybrid nanoflower via biomacromolecule-regulated biomimetic mineralization to immobilize sucrose phosphorylase (SPase). It was found that chitosan (CS) effectively regulated the biomimetic mineralization of calcium phosphate (CaP), leading to the formation of flower-like hybrid materials for the entrapment of SPase via self-assembly to establish a nano-biocatalyst (CS-CaP@SPase). Upon immobilization, the obtained CS-CaP@SPase exhibited excellent pH, by-product and organic solvents tolerance, and storage stability. Specifically, at acidic condition (pH 4), CS-CaP@SPase performed over 80 % of initial activity, which was 2.42-folds higher than that of free SPase. The catalytic activity of free SPase was severely inhibited about 30 % in the presence of fructose (1.2 M), but CS-CaP@SPase only lost 5 % relative activity. The CS-CaP@SPase retained over 80 % of its relative activity, while the free SPase maintained <20 % of its relative activity in acetonitrile. The relative activity of CS-CaP@SPase was still retained about 80 % after 10 cycles and maintained 75 % after 15 days. Based on Raman spectra analysis, it was also found that the increased β-folding component of SPase in the secondary structure after immobilization was the main factor for its enhanced stability. It is reasonable to believe that biomacromolecule-regulated biomimetic mineralization could be potentially used as a promising method to immobilize enzymes with excellent stability and recyclability, thereby facilitating the preparation of highly efficient catalysts for industrial biocatalysts, biosensing, and biomedicine.

Injectable hyaluronic acid/hydroxyapatite composite hydrogels as cell carriers for bone repair

The natural polysaccharide/hydroxyapatite hydrogels are of great interest to bone tissue engineering, but the interfacial mismatch between rigid hydroxyapatite and soft polysaccharide phase in these hydrogels remains unsolved, which is unfavorable to achieving uniform dispersion of hydroxyapatite particles in the hydrogel matrices. Herein, hyaluronic acid (Hya), an extracellular matrix constituent, was chosen as the template for biological mineralization to synthesize Hya/hydroxyapatite hybrid particles (HAHs). The oxidized Hya/hydroxyapatite hybrid particles (OHAHs) were obtained by oxidating the Hya in the HAHs. These OHAHs were the ball-flower particles hybridized with ca. 22 % oxidized Hya. Then, different concentrations of OHAHs were introduced to prepare hydroxyapatite composite hydrogels (HCH) via Schiff-base reaction of oxidized Hya and carboxymethyl chitosan. The injectability and self-healing of HCH were evaluated and the introduction of OHAHs significantly increased the storage modulus. The gelation time of HCH showed a negative relation with the concentration of OHAHs while the storage modulus presented a positive correlation. MTT assays and live/dead staining of L929 cells co-cultured with HCH confirmed that the hydrogels had excellent cytocompatibility, and supported the adhesion and proliferation of cells under the three-dimension culture conditions. These injectable self-healing hydrogels suitable for cell encapsulation were potentially useful for bone defect repair.

Superhydrophilic polyethersulfone (PES) membranes with high scale inhibition properties obtained through bionic mineralization and RTIPS

Reverse thermally induced separation (RTIPS) was used to obtain a separation membrane with a better internal structure for a higher water flux and a surface that could easily form a hydration layer. In comparison to the traditional modification method, this work focused on the aspect that the internal structure obtained by changing the membrane-making method provided easier adhesion conditions for the dopamine/TiO₂ hybrid nanoparticles (DA/TiO₂ HNPs) obtained by biomimetic mineralization. It provided a basis for exploring the variation in adhesion with the water bath temperature and the amount of titanium added through the study of turbidity point, SEM images, water contact angle, thermogravimetric test, EDX, AFM, XPS, FTIR and other test results. The SEM images proved that the membrane obtained through the RTIPS method had a porous surface and spongy internal structure, furthermore, additional polymers were adsorbed. Use of EDX demonstrated that biomimetic mineralization prevented the production of agglomerated titanium dioxide. XPS and FTIR spectra confirmed the introduction and immobilization of HNP aggregation. Moreover, a decrease in the surface roughness and water contact angle further suggested an improvement in the hydrophilicity of the modified membrane. The introduction of HNP at a higher water bath temperature helped increase the water flux up to ten times, moreover, the oil-water separation efficiency could still reach over 99.50%. Lastly, a cycle test of the modified membrane under the optimal conditions helped confirm that the membrane forming conditions at this time could provide a better environment for the formation of the hydrophilic layer, which was conducive to the recycling of the separation membrane. In summary, more fixed more hydrophilic particles could be obtained through the RTIPS method based on biomimetic mineralization to prevent the accumulation of titanium dioxide, thus helping improve permeability and anti-fouling of the membrane.

A hybrid nanobiocatalyst with in situ encapsulated enzyme and exsolved Co nanoclusters for complete chemoenzymatic conversion of methyl parathion to 4-aminophenol

Combination of enzymatic and chemical reactions provides tremendous possibilities for chemoenzymatic cascade processes. However, constructing efficient hybrid catalysts still faces great challenges. Herein, we develop a hybrid catalyst by in situ encapsulating organophosphorus hydrolase (OPH) into a Zn-doped Co-based ZIF (0.8CoZIF) via biomimetic mineralization for the chemoenzymatic cascade conversion of methyl parathion to 4-nitrophenol and then 4-aminophenol. The exsolved Co nanoclusters in Zn/Co-ZIF are found to catalyze 4-nitrophenol reduction into 4-aminophenol in the presence of sodium borohydride (NaBH₄). The as-synthesized OPH@0.8CoZIF catalyzes the complete conversion of 95 μM methyl parathion at nearly 100% 4-aminophenol production in the presence of 50 mM NaBH₄ within 15 min, which is 1/4 that of the physical mixture of OPH and 0.8CoZIF, benefiting from the MP accumulation and substrate channeling in the hybrid catalyst. The maximum cascade conversion rate of MP to 4-AP reaches 8.07 μmol·min^-1·g-catalyst^-1, which is higher than most of the reported chemoenzymatic cascade catalysts. Therefore, the hybrid nanocatalyst containing Co-ZIF-based catalyst and OPH is successfully fabricated and enables to catalyze the complete conversion of a toxic pollutant like methyl parathion into a non-toxic resource like 4-aminophenol for recycling in useful chemical synthesis through efficient one-pot cascade reactions.

Effective improvements to the live-attenuated Newcastle disease virus vaccine by polyethylenimine-based biomimetic silicification

Live and killed vaccines impart a significant role in preventing of Newcastle disease (ND) in China. Vaccine efficacy could be ameliorated by improving vaccine-induced cellular immunity and antibody persistency. Previous studies substantiated the potency of silicon dioxide (SiO₂) in the control-release of drugs and as a vaccine adjuvant, and polyethylenimine (PEI) merits as a mucosal adjuvanticity with electro-positivity. The present study employed SiO₂ and PEI to prepare biomimetic silicon mineralized nanoparticle G7M@SiO₂-PEI and microparticle (SiO₂ + PEI)@G7M vaccines of G7M, a candidate for live attenuated vaccine of genotype VII Newcastle disease virus (NDV). The zeta potential experiment confirmed the significant increase in the average zeta potential of the nanoparticle G7M@SiO₂-PEI and microparticle (SiO₂ + PEI)@G7M relative to G7M before mineralization. The results of RT-qPCR revealed more than 99% mineralization efficiency of the G7M@SiO₂-PEI and (SiO₂ + PEI)@G7M. The morphology detected by transmission electron microscopy reported that the diameters of G7M@SiO₂-PEI were similar to those of G7M, while for (SiO₂ + PEI)@G7M, it was about five times larger than that of G7M. Silicon was detected on the surface of both mineralization particles, except for G7M, as observed from the elemental distribution detected by elemental mapping and energy dispersive X-ray spectrogram. Indirect immunofluorescence assays validated that mineralization virus have replicated ability in BHK-21F cells. In vivo experiments revealed higher than 5.50 log₂ of antibody in nanoparticles G7M@SiO₂-PEI group until 10-week post-vaccination, and significant proliferation of antigen-specific CD3⁺CD4⁺ in nanoparticles G7M@SiO₂-PEI immunized group corroborated improved cellular immune responses. Vaccines provided full protection to the immunized chickens, whereas all the chickens receiving mock immunizations succumbed to the disease. Overall, our study concluded the efficacy of biomimetic mineralization of live attenuated vaccine in nanoparticles to improve humoral and cellular immune responses.

Hydroxypropylmethylcellulose as a film and hydrogel carrier for ACP nanoprecursors to deliver biomimetic mineralization

Demineralization of hard tooth tissues leads to dental caries, which cause health problems and economic burdens throughout the world. A biomimetic mineralization strategy is expected to reverse early dental caries. Commercially available anti-carious mineralizing products lead to inconclusive clinical results because they cannot continuously replenish the required calcium and phosphate resources. Herein, we prepared a mineralizing film consisting of hydroxypropylmethylcellulose (HPMC) and polyaspartic acid-stabilized amorphous calcium phosphate (PAsp-ACP) nanoparticles. HPMC which contains multiple hydroxyl groups is a film-forming material that can be desiccated to form a dry film. In a moist environment, this film gradually changes into a gel. HPMC was used as the carrier of PAsp-ACP nanoparticles to deliver biomimetic mineralization. Our results indicated that the hydroxyl and methoxyl groups of HPMC could assist the stability of PAsp-ACP nanoparticles and maintain their biomimetic mineralization activity. The results further demonstrated that the bioinspired mineralizing film induced the early mineralization of demineralized dentin after 24 h with increasing mineralization of the whole demineralized dentin (3-4 µm) after 72-96 h. Furthermore, these results were achieved without any cytotoxicity or mucosa irritation. Therefore, this mineralizing film shows promise for use in preventive dentistry due to its efficient mineralization capability.

Immobilization of Escherichia coli cells harboring a nitrilase with improved catalytic properties though polyethylenemine-induced silicification on zeolite

In the chemical-biological synthesis route of gabapentin, immobilized Escherichia coli cells harboring nitrilase are used to catalyze the biotransformation of intermediate 1-cyanocyclohexaneacetonitile to 1-cyanocyclohexaneacetic acid. Herein, we present a novel cell immobilization method, which is based on cell adsorption using 75 g/L Escherichia coli cells and 6 g/L zeolite, cell crosslinking using 3 g/L polyethylenemine and biomimetic silicification using 18 g/L hydrolyzed tetramethylorthosilicate. The constructed "hybrid biomimetic silica particles (HBSPs)" with core-shell structure showed a specific activity of 147.2 ± 2.3 U/g, 82.6 ± 2.8% recovery of nitrilase activity and a half-life of 19.1 ± 1.9 h at 55 °C. 1-Cyanocyclohexaneacetonitrile (1.0 M) could be completely hydrolyzed by 50 g/L of HBSPs at pH 7.5, 35 °C in 4 h, providing 92.1 ± 3.2% yield of 1-cyanocyclohexaneacetic acid. In batch reactions, the HBSPs could be reused for 13 cycles and maintained 79.9 ± 4.1% residual activity after the 10th batch, providing an average product yield of 92.6% in the first 10 batches with a productivity of 619.3 g/L/day. In addition, multi-layer structures consisting of silica coating and polyethylenemine/glutaraldehyde crosslinking were constructed to enhance the mechanical strength of immobilized cells, and the effects of coating layers on the catalytic properties of immobilized cells was discussed.

Modulating the biofunctionality of enzyme-MOF nanobiocatalyst through structure-switching aptamer for continuous degradation of BPA

Encapsulating enzyme within MOF (enzyme-MOF) gives rise to new opportunity to improve the fragility of enzyme, but practical application of enzyme-MOF composite is far from being realized. The development of a novel enzyme-MOF composite system should simultaneously guarantee the enhanced activity and controllably complete recycling, and only in this way can we efficiently and economically utilize the enzyme-MOF composite. Herein, we addressed all these fundamental limitations of current enzyme-MOF composite by establishing aptamer-functionalized enzyme-MOF composite (HRP-ZIF-8@P1). HRP-ZIF-8@P1 relied on automatic structure switch of aptamer-target binding and aptamer-cDNA (complementary DNA) hybridization, achieving effectiveness in self-enriching substrate around HRP-ZIF-8@P1 to boost enzymatic activity first, subsequently hybridizing spontaneously with magnetically controllable cDNA sequence (Fe₃O₄@P3) to completely recover the HRP-ZIF-8@P1, where preferentially capturing substrate could further induce the release of the hybridized HRP-ZIF-8@P1 for automatically starting the cyclic enzyme catalysis. A 5.6-fold enhancement in the catalytic efficiency for BPA degradation was endowed, and 94.7% catalytic activity was retained for 8 consecutive degradations of BPA, both of which were even more significant than HRP-ZIF-8. Additionally, remarkable stability of HRP-ZIF-8@P1 was afforded by dual-layer protection of ZIF-8 and P1 in denaturing conditions. Taking the possibility of discovering an aptamer for any target into account, the aptamer-functionalized enzyme-MOF composites provide a generic and simple guide for simultaneously boosting enzymatic activity and controllably full recycling the enzyme-MOF systems, accelerating their commercial utilizations.

An enamel-inspired bioactive material with multiscale structure and antibacterial adhesion property

Conventional dental materials lack of the hierarchical architecture of enamel that exhibits excellent intrinsic-extrinsic mechanical properties. Moreover, restorative failures frequently occur due to physical and chemical mismatch between artificial materials and native dental hard tissue followed by recurrent caries which is caused by sugar-fermenting, acidogenic bacteria invasion of the defective cite. In order to resolve the limitations of the conventional dental materials, the aim of this study was to establish a non-cell-based biomimetic strategy to fabricate a novel bioactive material with enamel-like structure and antibacterial adhesion property. The evaporation-based, bottom-up and self-assembly method with layer-by-layer technique were used to form a large-area fluorapatite crystal layer containing antibacterial components. The multilayered structure was constructed by hydrothermal growth of the fluorapatite crystal layer and highly conformal adsorption to the crystal surface of a polyelectrolyte matrix film. Characterization and mechanical assessment demonstrated that the synthesized bioactive material resembled the native enamel in chemical components, mechanical properties and crystallographic structure. Antibacterial and cytocompatibility evaluation demonstrated that this material had the antibacterial adhesion property and biocompatibility. In combination with the molecular dynamics simulations to reveal the effects of variables on the crystallization mechanism, this study brings new prospects for the synthesis of enamel-inspired materials.

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A simple chemistry approach was offered to synthesize a enamel-like material without using cells or proteins.

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A macroscopic bioactive material resembled the native enamel with the antibacterial adhension propery was fabricated.

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Combining experiments and molecular dynamics simulations revealed effects of variables on the crystallization mechanism.

Fabrication and characterization of purified esterase-embedded zeolitic imidazolate frameworks for the removal and remediation of herbicide pollution from soil

The fragility and high cost of enzymes represent critical challenges limiting their practical application in the removal of pesticides. Herein, an aryloxyphenoxypropionate herbicide-hydrolyzing enzyme, QpeH, was purified via one-step affinity chromatography and embedded into two types of zeolitic imidazolate frameworks (ZIFs) through biomimetic mineralization. The catalytic activity towards the herbicide quizalofop-P-ethyl, the loading capacity and efficiency of the resulting two composites, QpeH@ZIF-10 with cruciate flower-like morphology and QpeH@ZIF-8 with rhombic dodecahedral morphology, were compared. Both composites had excellent stability and reusability after 10 reuse cycles, with QpeH@ZIF-10 having a better performance. More importantly, when applied for the removal of quizalofop-P-ethyl pollution in the watermelon field, QpeH@ZIF-10 (88%) showed a remarkably improved degradation efficiency compared to QpeH@ZIF-8 (84%) despite the latter having a greater loading capacity. Finally, the use of QpeH@ZIF composites was shown to recover the bacterial community in soil. This work provides a new insight into the low-cost synthesis of nanobiocatalysts combining simple purified enzymes and metal-organic frameworks (MOFs) for the remediation of pesticide-contaminated soils.

Gas assisted in situ biomimetic mineralization of bacterial cellulose/calcium carbonate bio composites by bacterial

Biomineralization inspired process to produce polymer of desired need is a promising approach in the field of research. In the present work, the bacterial cellulose (BC) based nanocomposites with a 3D network were synthesized via a biological route by choosing the calcium salt of primary metabolites (calcium gluconate) as the carbon source. The BC based composites were characterized by employing with Scanning Electron Microscopy (SEM) and Transmission Electron Microscopy (TEM). During the preparation of nanocomposites, the calcium ions embedded on the cellulose fibrils were served as the nucleation center and calcium carbonate was deposited into BC network in the assistance of CO₂. The uniform distribution of embedded objects on the cellulose nanofibers between internal and external was achieved. The exploitation of organisms for inorganic growth, shape and self-assembling explores new opportunities to the design of original nanostructures.

Biomimetic mineralized hybrid scaffolds with antimicrobial peptides

Infection in hard tissue regeneration is a clinically-relevant challenge. Development of scaffolds with dual function for promoting bone/dental tissue growth and preventing bacterial infections is a critical need in the field. Here we fabricated hybrid scaffolds by intrafibrillar-mineralization of collagen using a biomimetic process and subsequently coating the scaffold with an antimicrobial designer peptide with cationic and amphipathic properties. The highly hydrophilic mineralized collagen scaffolds provided an ideal substrate to form a dense and stable coating of the antimicrobial peptides. The amount of hydroxyapatite in the mineralized fibers modulated the rheological behavior of the scaffolds with no influence on the amount of recruited peptides and the resulting increase in hydrophobicity. The developed scaffolds were potent by contact killing of Gram-negative Escherichia coli and Gram-positive Streptococcus gordonii as well as cytocompatible to human bone marrow-derived mesenchymal stromal cells. The process of scaffold fabrication is versatile and can be used to control mineral load and/or intrafibrillar-mineralized scaffolds made of other biopolymers.

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A biomimetic intrafibrillar-mineralized scaffold was prepared using a non-classical pathway for mineralization.

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The mineralized scaffold was stably coated with designer antimicrobial peptide GL13K.

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The hybrid scaffold was cytocompatible and potent against biofilms of model Gram-positive and Gram-negative bacteria.

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The mineral content affected the rheological properties of the scaffolds, but not the loading of antimicrobial peptides.

Improvement of organisms by biomimetic mineralization: A material incorporation strategy for biological modification

Biomineralization, a bio-organism controlled mineral formation process, plays an important role in linking biological organisms and mineral materials in nature. Inspired by biomineralization, biomimetic mineralization is used as a bridge tool to integrate biological organisms and functional materials together, which can be beneficial for the development of diversified functional organism-material hybrids. In this review, recent progresses on the techniques of biomimetic mineralization for organism-material combinations are summarized and discussed. Based upon these techniques, the preparations and applications of virus-, prokaryotes-, and eukaryotes-material hybrids have been presented and they demonstrate the great potentials in the fields of vaccine improvement, cell protection, energy production, environmental and biomedical treatments, etc. We suggest that more researches about functional organism and material combination with more biocompatible techniques should be developed to improve the design and applications of specific organism-material hybrids. These rationally designed organism-material hybrids will shed light on the production of "live materials" with more advanced functions in future. STATEMENT OF SIGNIFICANCE: This review summaries the recent attempts on improving biological organisms by their integrations with functional materials, which can be achieved by biomimetic mineralization as the combination tool. The integrated materials, as the artificial shells or organelles, confer diversified functions on the enclosed organisms. The successful constructions of various virus-, prokaryotes-, and eukaryotes-material hybrids have demonstrated the great potentials of the material incorporation strategy in vaccine development, cancer treatment, biological photosynthesis and environment protection etc. The suggested challenges and perspectives indicate more inspirations for the future development of organism-material hybrids.

Remineralization of dentine tubules induced by phosphate-terminated PAMAM dendrimers

Various sealants have been developed to treat the exposure of dentinal tubules (DTs) and further dental hypersensitivity. Herein, the phosphate-terminated fourth generation polyamidoamine dendrimers (PAMAM-PO₃H₂) was successfully synthesized. Six duplicates of demineralized dentin and type I collagen matrix were incubated in artificial saliva solution with or without PAMAM-PO₃H₂ treatment at 37 °C for 2 weeks, respectively. The artificial saliva solution was replaced every day. These regenerated crystals on the surface of dentin and collagen matrix were confirmed to be hydroxyapatite (HAp). The approach thus demonstrates that PAMAM-PO₃H₂ can offer an efficient therapy for seal DTs in clinical dentistry.

Environmental and intercellular Pb2+ ions determination based on encapsulated DNAzyme in nanoscale metal-organic frameworks

With the merits of low cost, simple synthesis procedure, and high affinity for metal ions, deoxyribozyme (DNAzyme) have played important roles in metal ions detection. However, the intracellular applications of DNAzyme are limited because of enzymatic degradation and inefficient cellular uptake. To address these problems, GR-5 as model DNAzyme was encapsulated into zeolitic imidazolate frameworks-8 (ZIF-8) nanoparticles by biomimetic mineralization. The positively charged ZIF-8 with high DNAzyme loading capacity retained their ability to enter cells. Compared with free DNAzyme, the biomimetic mineralization synthesis method has greatly improved the stability of pristine DNAzyme. The as-synthesized DNAzyme@ZIF-8 composite exhibited good stability resisting DNase I, and was used as a sensitive fluorescent nanoprobe for Pb²⁺ determination and successfully achieved selective and sensitive determination for Pb²⁺ at λ_ex/λ_em = 494/522 nm in real samples. The linear range for the determination of Pb²⁺ is 50 to 500 nM. Moreover, the highly active DNAzyme delivered by ZIF-8 allows noninvasive imaging of Pb²⁺ measurement in living cells. This strategy will extend the suitability of functional nucleic acids for in vitro and in vivo bioanalysis and bioimaging. Graphical abstract.

Are Bioceramics the Dernier Cri in the Management of Stage 4 Developed Root? A Finite Element Analysis

AIM

To compare the stress distribution of four modalities of reinforcing the radicular space of a pulpless central incisor exhibiting stage 4 root development.

MATERIALS AND METHODS

The model of a pulpless immature central incisor with a stage 4 of root development supporting periodontium was generated based on the properties. The longitudinal growth of the root was completed. Four such models were developed. Then, the radicular space was rehabilitated as follows: Model 1: Ceramicrete; Model 2: Biomimetic Mineralization; Model 3: Biodentine; Model 4: Bioaggregate. They were subjected to three different loading conditions. One was to mimic the mastication by applying a load of 70 N applied at 45° angle. Second loading condition was a vertical load of 100 N to mimic bruxism. The third loading condition was to mirror the impact of a frontal trauma. A load of 100 N was applied labially.

RESULTS

It was observed that during mastication, Model 2 has exhibited the lowest concentration of von Mises stresses, followed by Model 3 and then Model 4 followed by Model 1; this could be because the modulus of elasticity of Model 2 is comparable to that of Dentin. During bruxism and horizontal impact, the maximal stress concentration was found in Model 4, Model 3, Model 2, followed by Model 1.

CONCLUSION

The closer the elasticity of modulus of the primary endodontic replacement monoblock was to that of dentin, the lower were the stresses generated. However, as the increase in stress values was minimal between groups, these obturating materials can be viable reinforcement materials for the rehabilitation of cases of stage 4 developing root. Biomimetic mineralization strategies can be a viable treatment option for managing cases of the open apex.

CLINICAL RELEVANCE

Biomimetic mineralization strategies and bioceramics can be used for obturation of root canals with open apex, instead of utilizing these bioceramics as apical plugs.

Biomimetic mineralization of novel hydroxyethyl cellulose/soy protein isolate scaffolds promote bone regeneration in vitro and in vivo

Although various strategies have been utilized to accelerate bone regeneration in bone tissue engineering (BTE), the treatment and repair of large bone defects remains a clinical challenge worldwide. Inspired by the natural extracellular matrix of bone tissue, organic-inorganic composite scaffolds with three-dimensional (3D) porous structures, sufficient mechanical properties, excellent cytocompatibility, osteoconductivity, and osteogenic potential have received considerable attention within the field of bone engineering. In this work, a novel epichlorohydrin (ECH)-crosslinked hydroxyethyl cellulose (HEC)/soy protein isolate (SPI) porous bi-component scaffold (EHSS) with hydroxyapatite (HAp) functionalization (EHSS/HAp) was constructed for bone defect repair via the combination of lyophilization and in situ biomimetic mineralization. Systematic characterization experiments were performed to assess the morphology, HAp-forming properties, mechanical properties and degradation rate of the scaffold. The results indicated that the prepared scaffolds exhibited an interconnected porous structure, a biomimetic HAp coating on their surfaces, improved mechanical properties in compression and a controllable degradation rate. In particular, semiquantitative analysis showed that the calcium/phosphorus (Ca/P) ratio of EHSS/HAp with 70% SPI content (1.65) was similar to that of natural bone tissue (1.67) according to energy dispersive X-ray spectroscopy analysis. In vitro cell culture experiments indicated that the EHSS/HAp with 70% SPI content showed improved cytocompatibility and was suitable for MC3T3-E1 cell attachment, proliferation and growth. Consistently, in vitro osteogenic differentiation studies showed that EHSS/HAp with 70% SPI content can significantly accelerate the expression of osteogenesis-related genes (Col-1, Runx2, OPN, and OCN) during osteogenic differentiation of MC3T3-E1 cells. Furthermore, when applied to the repair of critical-sized cranial defects in a rat model, EHSS/HAp with 70% SPI was capable of significantly promoting tissue regeneration and integration with native bone tissue. Microscopic computed tomography (micro-CT) results demonstrated that the bone defect site was nearly occupied with newly formed bone at 12 weeks after implantation of EHSS/HAp with 70% SPI content into the defect. Hematoxylin and eosin (H&E) staining and Masson's trichrome staining of histological sections further confirmed that EHSS/HAp with 70% SPI markedly promoted new bone formation and maturation. Collectively, our results demonstrate the potential of EHSS/HAp scaffolds with 70% SPI for successful bone defect repair and regeneration.

[The Effect of PAMAM Dendrimer on the Dentin Remineralization and Matrix Metalloproteinases Activity]

OBJECTIVE

The purpose of this study was to investigate the effect of G4.5 carboxyl-terminated poly dendrimer (PAMAM-COOH) on the dentin remineralization and the matrix metalloproteinases (MMPs) activity.

METHODS

The dentine samples were averagely divided into four groups: 100 mg/mL PAMAM-COOH group (A group), 10 mg/mL PAMAM-COOH group (B group), 2% (wt) chlorhexidine (CHX) group (C group) and deionized water group (Control group). MMP Activity Assay Kit was used to detect the activity of dentin endogenous MMPs in the four groups. The loss of dry mass of dentin after 30 d were measured. In situ zymography analysis was performed to detect the effects of PAMAM dendrimer in each group (except A group) on gelatinase activity in dentin. After incubation in artificial saliva for 7 and 14 d incubated, the remineralization of each group (except A group) in dentin surfaces were examined using a field emission-scanning electron microscope (FESEM).

RESULTS

Compared with the control group, the dentin endogenous MMPs activity in A, B and C groups were all decreased ( P<0.05). The activity of endogenous MMPs in C group was lower than that of A and B groups ( P<0.001), but the difference between A and B groups was not statistically significant. The loss of dry mass in A, B and C groups were lower than that in control group ( P<0.05), but there were no significant difference in A, B and C groups. The in situzymography analysis showed that 48 h later, the dentin gelatinase activity in B group was inhibited compared with the control group, but the inhibitory effect was weaker than that of CHX. After 7 d and 14 d, there were no obvious mineralization in the control group, while distinct mineralization were observed in B group. The mineralization effect in group B was better than group C.

CONCLUSION

G4.5 PAMAM-COOH could introduce remineralizationin and demineralizeddentin by effectively inhibiting endogenous MMPs and gelatinase, thus contributes as novel material to enhancing durability of adhesion.

Mechanical behavior of biomimetically mineralized collagen matrix using the polymer - induced liquid precursor process

Biomimetic mineralization is a promising technique in biomedical applications. To understand the mechanical behavior of biomimetically mineralized collagen material (BMC), we examined the composition and structure of the mineral deposition in BMCs mineralized by the polymer-induced liquid precursor (PILP) process and applied wide angle x-ray scattering (WAXS) with in situ tensile testing to investigate the mineral-to-tissue co-deformation in the material. We found that the PILP process is able to achieve good biomimetic mineralization in bulk collagen matrix. Compositionally, the mineral deposition showed high crystallinity with no carbonation. However, the morphology of extrafibrillar mineral deposition and the preferential crystal orientation were different from natural bone. Further, the Young's modulus and mineral-to-tissue co-deformation ratio of the BMC were significantly lower than both natural bone and partially demineralized bone with similar mineral volume fraction. It was concluded that while biomimetic mineralization can achieve good mineral deposition volume in the BMC, the mechanical behavior of the material was different from natural bone.

Improving laccase activity and stability by HKUST-1 with cofactor via one-pot encapsulation and its application for degradation of bisphenol A

Enhancing the catalytic activity and stability of enzymes is of great importance in the development of green chemical and cost-effective application, with removal of bisphenol A (BPA) as a prominent example. Engineering immobilization carriers and immobilization methods of enzymes endows great potential to achieve above goal. Until now, these reports have focused on employing the metal-organic frameworks (MOFs) to increase the stability and reusability of enzymes, an enhancement in its catalytic activity has yet to be addressed. This work introduced a biomimetic mineralization process for facile synthesis of laccase@HKUST-1 biocomposite under mild condition. By exploiting the activity of laccase@HKUST-1, we demonstrated, for the first time, that the integration of laccase and HKUST-1 containing cofactor Cu²⁺ ions leaded to 1.5-fold enhancement in the catalytic activity compared with free laccase, which was due to the synergistic enhancement of substrate oxidation. Indeed, the laccase@HKUST-1 biocomposite could function as active biocatalysts under biologically challenging conditions, such as acidic condition, high temperature, organic solvent, and continuous operation. The oxidation of phenols, such as BPA, with laccase@HKUST-1 reached higher catalytic performance than free laccase, and gave 100% degradation efficiency within 4 h. This study provides a feasible method to improve the activity and stability of laccase, which enable completely remove of BPA from the environment.

Novel bone-mimetic nanohydroxyapatite/collagen porous scaffolds biomimetically mineralized from surface silanized mesoporous nanobioglass/collagen hybrid scaffold: Physicochemical, mechanical and in vivo evaluations

Bone-mimetic scaffolds are receiving much interest as such scaffolds exhibit excellent biocompatibility and very close mimic to bone structure and composition. Here, novel bone-mimetic nanohydroxyapatite (nHA)/collagen (Col) porous scaffolds (nHA/Col) were prepared from surface silanized mesoporous nanobioglass (NBG)/Col hybrid scaffold by biomimetic mineralization. Surface silanized mesoporous NBG was prepared by ultrasound-assisted sol-gel method and post treatment with 3-aminopropyltriethylsilane (APTS). The surface silanized mesoporous NBG was characterized by transmission electron microscopy (TEM), transmission electron microscopy-selected area electron diffraction (TEM-SAED) and X-ray photoelectron spectroscopy (XPS). The physicochemical/mechanical characterizations of the scaffolds included scanning electron microscopy (SEM) and TEM imaging of micro/nanostructure, energy dispersive X-ray (EDX) analysis of chemical composition, TEM-SAED and X-ray diffraction/Attenuated total Reflectance-Fourier Infrared spectroscopy (XRD/ATR-FTIR) analyses of amorphous-to-crystalline transformations, thermogravimetric/differential scanning calorimetric (TGA/DSC) analyses of thermal behaviour , porosity and dynamic mechanical analyses. The presence of NBG in collagen fibrillar network enabled progressive growth of HA nanocrystals and generation of a novel bone-mimetic hybrid structures while preserving the highly porous structure of collagen scaffold. The crystallinity, crystallite size and crystal morphology of the grown HA nanocrystals were controllable by regulation of the mineralization time. Furthermore, the osteogenic properties of the non-mineralized (NBG/Col) and mineralized (nHA/Col) hybrid porous scaffolds were examined in vivo using critical-sized calvarial bone defect model in rat. Histological and micro-computed tomography (Micro-CT) analyses after 6 weeks of implantation revealed that the mineralized scaffolds possess excellent in vivo osteogenic potential compared to the non-mineralized one. Collectively, by using surface silanized mesoporous NBG hybridization with collagen fibrillar network, we successfully introduced a new approach for developing novel bone-mimetic nanohydroxyapatite/collagen hybrid scaffolds that possess significant potential for bone tissue regeneration.

Biomimetic mineralization behavior of COS-grafted silk fibroin following hexokinase-mediated phosphorylation

Silk fibroin (SF) has potential applications in the biomedical field because of its excellent mechanical properties and biocompatibility. In the current study, chitooligosaccharide (COS) was enzymatically grafted onto SF using laccase. Subsequently, COS-grafted SF (SF-g-COS) was treated enzymatically in the presence of hexokinase and Mg-chelated adenosine triphosphate (ATP), so as to introduce phosphate groups onto the fibroin chains and promote the deposition of hydroxyapatite (HAp) during in situ biomimetic mineralization. The efficacy of phosphorylation and biomimetic mineralization of the SF-g-COS was evaluated by means of HPLC, MALDI-TOF MS, FTIR, XRD and EDS-Mapping. The results indicate that hexokinase has the capability to catalyze the phosphorylation of COS, resulting in an increase in the quantity of phosphorus in the SF-g-COS. Following mineralization of the phosphorylated SF-g-COS, a greater number of mineral phases were detected on its surface, accompanied by a higher content of calcium and phosphorus compared with other specimens. Cell viability tests using NIH/3T3 cells and cellular adhesion potential with MG-63 cells indicated that the fibroin-based biocomposite exhibited acceptable biocompatibility and superior cellular adhesion properties. The present study describes a novel method for preparation of fibroin/HAp biocomposites for bone tissue engineering.

Synthesis of Metal-Organic Frameworks on Tobacco Mosaic Virus Templates

Tobacco mosaic virus (TMV) has long been exploited as a robust biological scaffold for organic/inorganic modification owing to its anisotropic structure and chemically addressable amino acid residues on both the exterior and interior. We present the fabrication of a crystalline microporous metal-organic framework (MOF) shell on the exterior of TMV, which retains its rod-like morphology, and produces uniformly formed core-shell structures with high accessible surface area and pore volume. We also describe an exfoliation method that can recover the intact viral particle from the core-shell composite.

Ulvan-chitosan polyelectrolyte complexes as matrices for enzyme induced biomimetic mineralization

Polyelectrolyte complexes (PEC) of chitosan and ulvan were fabricated to study alkaline phosphatase (ALP) mediated formation of apatitic minerals. Scaffolds of the PEC were subjected to ALP and successful mineral formation was studied using SEM, Raman and XRD techniques. Investigation of the morphology via SEM shows globular structures of the deposited minerals, which promoted cell attachment, proliferation and extracellular matrix formation. The PEC and their successful calcium phosphate based mineralization offers a greener route of scaffold fabrication towards developing resorbable materials for tissue engineering.

Coupling process study of lipid production and mercury bioremediation by biomimetic mineralized microalgae

Considering the high concentration of mercury in industrial wastewater, such as coal-fired power plants and gold mining wastewater, this research study investigated the coupling process of lipid production and mercury bioremediation using microalgae cells. Chlorella vulgaris modified by biomimetic mineralization. The cultivation was divided in two stages: a natural cultivation for 7days and 5days of Hg²⁺ addition (10-100μg/L) for cultivation at different pH values (4-7) after inoculation. Next, the harvested cells were eluted, and lipid was extracted. The fluorescein diacetate (FDA) dye tests demonstrated that the mineralized layer enhanced the biological activity of microalgae cells in Hg²⁺ contaminated media. Hg distribution tests showed that the Hg removal capacity of modified cells was increased from 62.85% to 94.74%, and 88.72% of eluted Hg²⁺ concentration was observed in modified cells compared to 48.42% of raw cells, implying that more mercury was transferred from lipid and residuals into elutable forms.

Biomimetically grown apatite spheres from aggregated bioglass nanoparticles with ultrahigh porosity and surface area imply potential drug delivery and cell engineering applications

Here we communicate the generation of biomimetically grown apatite spheres from aggregated bioglass nanoparticles and the potential properties applicable for drug delivery and cell/tissue engineering. Ion releasing nanoparticulates of bioglass (85%SiO₂-15%CaO) in a mineralizing medium show an intriguing dynamic phenomenon - aggregation, mineralization to apatite, integration and growth into micron-sized (1.5-3μm) spheres. During the progressive ionic dissolution/precipitation reactions, nano-to-micro-morphology, glass-to-crystal composition, and the physico-chemical properties (porosity, surface area, and charge) change dynamically. With increasing reaction period, the apatite becomes more crystallized with increased crystallinity and crystal size, and gets a composition closer to the stoichiometry. The developed microspheres exhibit hierarchical surface nanostructure, negative charge (ς-potential of -20mV), and ultrahigh mesoporosity (mesopore size of 6.1nm, and the resultant surface area of 63.7m²/g and pore volume of 0.153cm³/g) at 14days of mineralization, which are even higher than those of its precursor bioglass nanoparticles. Thanks to these properties, the biomimetic mineral microspheres take up biological molecules effectively, i.e., loading capacity of positive-charged protein is over 10%. Of note, the release is highly sustainable at a constant rate, i.e., profiling almost 'zero-order' kinetics for 4weeks, suggesting the potential usefulness as protein delivery systems. The biomimetic mineral microspheres hold some remnant Si in the core region, and release calcium, phosphate, and silicate ions over the test period, implying the long-term ionic-related therapeutic functions. The mesenchymal stem cells favour the biomimetic spheres with an excellent viability. Due to the merit of sizes (a few micrometers), the spheres can be intercalated into cells, mediating cellular interactions in 3D cell-spheroid engineering, and also can stimulate osteogenic differentiation of cells when incorporated into cell-laden gels. The intriguing properties observed in this study, including biomimetic composition, high mesoporosity, release of therapeutic ions, effective loading and long-term release of proteins, and diverse yet favorable 3D cellular interactions, suggest great potential of the newly developed biomimetic microspheres in biomedical applications, such as drug delivery and cell/tissue engineering.

STATEMENT OF SIGNIFICANCE

This work reports the generation of apatite spheres with a few micrometers in size biomimetically grown from bioactive glass nanoparticles, through a series of intriguing yet unprecedented phenomenon involving aggregation of nanoparticles, mineralization and sphere growth. The mineral microspheres possess some unique physico-chemical properties including mesoporosity, ultrahigh surface area, and therapeutic ionic release. Furthermore, the spheres show excellent loading and delivery capacity of protein molecules, and mediate favorable cellular interactions in 2D and 3D culture conditions, demonstrating a future multifunctional microcarrier platform for the therapeutics delivery and cell/tissue engineering.

Synthesis of silk fibroin-g-PAA composite using H2O2-HRP and characterization of the in situ biomimetic mineralization behavior

Silk fibroin (SF) as a bioactive protein can offer growth substrates for hydroxyapatite (HAp) deposition. In the current work, graft copolymerization of acrylic acid (AA) onto fibroin chains was carried out using hydrogen peroxide-horseradish peroxidase (H₂O₂-HRP) catalytic system, SF-g-polyacrylic acid (PAA) membranes was prepared subsequently, followed by in situ biomimetic mineralization in the Ca/P solutions, aiming at promoting the deposition of HAp and endowing the fibroin-based biocomposite with enhanced bioactivity. Meanwhile, p-hydroxyphenylacetamide (PHAD) and methyl acrylate (MA), as the model compounds of tyrosine residues in SF and vinyl monomer were used to disclose the mechanism of graft copolymerization. The data from FTIR and SEC chromatograms indicated that vinyl monomer was successfully graft copolymerized with SF during H₂O₂-HRP treatment. According to the results of XRD, SEM patterns and EDS-Mapping, mineral phases on the surfaces of SF-g-PAA membranes were detected after different cycles of biomimetic mineralization, and the mechanical property of SF-g-PAA/HAp membrane was noticeably improved. Cell viability and adhesion assays revealed that the composite of SF-g-PAA/HAp exhibited acceptable biocompatibility and outstanding adhesion property. The present work provides a novel method for preparation of the fibroin-based biomaterial for bone tissue engineering.

Promoting spinal fusions by biomineralized silk fibroin films seeded with bone marrow stromal cells: An in vivo animal study

OBJECTIVES

To prepare a biomineralized nano silk fibroin film seeded with bone marrow stromal cells (BMSCs), and to evaluate its performance in spinal fusion.

METHODS

The silk fibroin film was mineralized in a modified, simulated body fluid, seeded with BMSCs, and evaluated in a rat model of posterolateral lumbar fusion, compared with pure silk fibroin, silk fibroin/bone marrow stromal cells, mineralized silk fibroin, mineralized silk fibroin/bone marrow stromal cells, iliac crest bone, and no graft. After 12 weeks, all rats were sacrificed and underwent manual palpation, micro-CT scanning, biomechanical testing, and histology.

RESULTS

The infrared spectrum, X-ray diffraction, and scanning electron microscopy demonstrated deposition of mineral layers on the silk fibroin film surface. The fusion rate, bone volume, relative strength and stiffness, and histological score of the mineralized silk fibroin/bone marrow stromal cells were slightly lower than the autograft, but without any significant difference (p > 0.05). In addition, the mineralized silk fibroin was significantly greater in most parameters than the silk fibroin/bone marrow stromal cells (p < 0.05).

CONCLUSION

The mineralized silk fibroin resembles natural bone structurally, and the cellular and mineral layers of silk fibroin are both critical to bone regeneration. The ability to promote spinal fusion is enhanced when the mineralized silk fibroin is seeded with bone marrow stromal cells.

Crystallization of dicalcium phosphate dihydrate with presence of glutamic acid and arginine at 37 °C

The formations of non-metabolic stones, bones and teeth were seriously related to the morphology, size and surface reactivity of dicalcium phosphate dihydrate (DCPD). Herein, a facile biomimetic mineralization method with presence of glutamic acid and arginine was employed to fabricate DCPD with well-defined morphology and adjustable crystallite size. In reaction solution containing more arginine, crystallization of DCPD occurred with faster rate of nucleation and higher density of stacked layers due to the generation of more OH(-) ions after hydrolysis of arginine at 37 °C. With addition of fluorescein or acetone, the consumption of OH(-) ions or desolvation reaction of Ca(2+) ions was modulated, which resulted in the fabrication of DCPD with adjustable crystallite sizes and densities of stacked layers. In comparison with fluorescein-loading DCPD, dicalcium phosphate anhydrate was prepared with enhanced photoluminescence properties due to the reduction of self-quenching effect and regular arrangement of encapsulated fluorescein molecules. With addition of more acetone, DCPD was prepared with smaller crystallite size via antisolvent crystallization. The simulated process with addition of amino acids under 37 °C would shed light on the dynamic process of biomineralization for calcium phosphate compounds.