Biomimetic synthesis of calcium carbonate with different morphologies and polymorphs in the presence of bovine serum albumin and soluble starch

Size Control of Biomimetic Curved-Edge Vaterite with Chiral Toroid Morphology via Sonochemical Synthesis

The metastable vaterite polymorph of calcium carbonate (CaCO3) holds significant practical importance, particularly in regenerative medicine, drug delivery, and various personal care products. Controlling the size and morphology of vaterite particles is crucial for biomedical applications. This study explored the synergistic effect of ultrasonic (US) irradiation and acidic amino acids on CaCO3 synthesis, specifically the size, dispersity, and crystallographic phase of curved-edge vaterite with chiral toroids (chiral-curved vaterite). We employed 40 kHz US irradiation and introduced L- or D-aspartic acid as an additive for the formation of spheroidal chiral-curved vaterite in an aqueous solution of CaCl2 and Na2CO3 at 20 ± 1 °C. Chiral-curved vaterites precipitated through mechanical stirring (without US irradiation) exhibited a particle size of approximately 15 μm, whereas those formed under US irradiation were approximately 6 μm in size and retained their chiral topoid morphology. When a fluorescent dye was used for the analysis of loading efficiency, the size-reduced vaterites with chiral morphology, produced through US irradiation, exhibited a larger loading efficiency than the vaterites produced without US irradiation. These results hold significant value for the preparation of biomimetic chiral-curved CaCO3, specifically size-reduced vaterites, as versatile biomaterials for material filling, drug delivery, and bone regeneration.

Effect of proteins on biocementation in construction materials

This study examines the effect of proteins on the binding property and microstructure of enzymatic-induced calcium carbonate precipitation (EICP) in cementitious environment. The protein modified precipitates generally demonstrated improved binding to a glass slide surface or cement paste surface compared to the control precipitate. A marked decrease in the amount and binding strength of the precipitates in the cementitious environment was observed due to a reduction in the urease enzyme activity. The protein modified precipitates exhibited noticeable improvement compared to the control precipitate in cementitious environment which could arise from the ability of the proteins to partially shield urease from the negative effect of high pH. The protein gel network formation due to the complexation between the proteins and Ca2+ provides nucleation sites for CaCO3 crystallization. The FTIR, SEM, TGA, and XRD results indicated that vaterite is the dominant polymorph in cementitious environment compared to calcite in deionized water.

Statistical 3D morphology characterization of vaterite microspheres produced by engineered Escherichia coli

Hollow vaterite microspheres are important materials for biomedical applications such as drug delivery and regenerative medicine owing to their biocompatibility, high specific surface area, and ability to encapsulate a large number of bioactive molecules and compounds. We demonstrated that hollow vaterite microspheres are produced by an Escherichia coli strain engineered with a urease gene cluster from the ureolytic bacteria Sporosarcina pasteurii in the presence of bovine serum albumin. We characterized the 3D nanoscale morphology of five biogenic hollow vaterite microspheres using 3D high-angle annular dark field scanning transmission electron microscopy (HAADF-STEM) tomography. Using automated high-throughput HAADF-STEM imaging across several sample tilt orientations, we show that the microspheres evolved from a smaller more ellipsoidal shape to a larger more spherical shape while the internal hollow core increased in size and remained relatively spherical, indicating that the microspheres produced by this engineered strain likely do not contain the bacteria. The statistical 3D morphology information demonstrates the potential for using biogenic calcium carbonate mineralization to produce hollow vaterite microspheres with controlled morphologies. STATEMENT OF SIGNIFICANCE: The nanoscale 3D structures of biomaterials determine their physical, chemical, and biological properties, however significant efforts are required to obtain a statistical understanding of the internal 3D morphology of materials without damaging the structures. In this study, we developed a non-destructive, automated technique that allows us to understand the nanoscale 3D morphology of many unique hollow vaterite microspheres beyond the spectroscopy methods that lack local information and microscopy methods that cannot interrogate the full 3D structure. The method allowed us to quantitatively correlate the external diameters and aspect ratios of vaterite microspheres with their hollow internal structures at the nanoscale. This work demonstrates the opportunity to use automated transmission electron microscopy to characterize nanoscale 3D morphologies of many biomaterials and validate the chemical and biological functionality of these materials.

A Study on Bio-Stabilisation of Sub-Standard Soil by Indigenous Soil Urease-Producing Bacteria

Sub-standard soils are of great concern worldwide due to diverse economic losses and the possibility of severe environmental hazards ranging from catastrophic landslides, building collapse, and erosion to loss of lives and properties. This study explored the potential of urease-producing bacteria, <i>Bacillus cereus</i> and <i>Bacillus paramycoides</i>, to stabilise sub-standard soil bio-stabilisation. The maximum urease activity measured by <i>B. cereus</i> and <i>B. paramycoides</i> was 665 U/mL and 620 U/mL, respectively. <i>B. cereus</i> and <i>B. paramycoides</i> precipitated 943 ± 57 mg/L and 793 ± 51 mg/L of CaCO₃ at an optical density (425 nm) of 1.01 and 1.09 and pH 8.83 and 8.59, respectively, after 96 hours of incubation. SEM microstructural analysis of the precipitated CaCO₃ revealed crystals of various sizes (2.0–23.0 µm) with different morphologies. XRD analysis confirmed that the precipitated CaCO₃ comprised calcite and aragonite crystals. SEM analysis of the microstructure of organic and sandy clay soils treated with <i>B. cereus</i> and <i>B. paramycoides</i> showed the formation of bio-precipitated calcium carbonate deposits on the soil particles (biocementing soil grains), with <i>B. cereus</i> precipitating more CaCO₃ crystals with a better biocementing effect compared to <i>B. paramycoides</i>. Overall, the experimental results attributed CaCO₃ formation to bacterial-associated processes, suggesting that soil ureolytic bacteria are potentially useful to stabilise sub-standard soil.

Reduction of bioavailability and phytotoxicity effect of cadmium in soil by microbial-induced carbonate precipitation using metabolites of ureolytic bacterium Ochrobactrum sp. POC9

The application of ureolytic bacteria for bioremediation of soil contaminated with heavy metals, including cadmium (Cd), allows for the efficient immobilization of heavy metals by precipitation or coprecipitation with carbonates. Microbially-induced carbonate precipitation process may be useful also in the case of the cultivation of crop plants in various agricultural soils with trace but legally permissible Cd concentrations, which may be still uptaken by plants. This study aimed to investigate the influence of soil supplementation with metabolites containing carbonates (MCC) produced by the ureolytic bacterium Ochrobactrum sp. POC9 on the Cd mobility in the soil as well as on the Cd uptake efficiency and general condition of crop plants (Petroselinum crispum). In the frame of the conducted studies (i) carbonate productivity of the POC9 strain, (ii) the efficiency of Cd immobilization in soil supplemented with MCC, (iii) crystallization of cadmium carbonate in the soil enriched with MCC, (iv) the effect of MCC on the physico-chemical and microbiological properties of soil, and (v) the effect of changes in soil properties on the morphology, growth rate, and Cd-uptake efficiency of crop plants were investigated. The experiments were conducted in soil contaminated with a low concentration of Cd to simulate the natural environmental conditions. Soil supplementation with MCC significantly reduced the bioavailability of Cd in soil with regard to control variants by about 27-65% (depending on the volume of MCC) and reduced the Cd uptake by plants by about 86% and 74% in shoots and roots, respectively. Furthermore, due to the decrease in soil toxicity and improvement of soil nutrition with other metabolites produced during the urea degradation (MCC), some microbiological properties of soil (quantity and activity of soil microorganisms), as well as the general condition of plants, were also significantly improved. Soil supplementation with MCC enabled efficient Cd stabilization and significantly reduced its toxicity for soil microbiota and plants. Thus, MCC produced by POC9 strain may be used not only as an effective Cd immobilizer in soil but also as a microbe and plant stimulators.

Nanosized vaterite production through organic-solvent-free indirect carbonation

Nanosized vaterite, which exhibits characteristics such as high specific surface area, porosity, and biocompatibility, has attracted research attention for use as a drug delivery material. However, fatal drawbacks such as high costs, difficulty in mass production, and toxicity exist in conventional nanosized vaterite production owing to the use of a large amount of organic solvents to forcibly suppress the vaterite recrystallization and particle growth. Therefore, nanosized 100 % vaterite was produced in this study via indirect carbonation without using any organic solvent, which has rarely been achieved previously. Seawater, sucrose, ultrasonication, and aging-which facilitate vaterite production and particle size reduction-exhibited a synergistic effect in producing vaterite. To realize nanosized vaterite production via indirect carbonation, seawater was used as a solvent, sucrose was added when Ca was eluted, and CO₂ bubbling was performed under ultrasonication. Furthermore, the CaCO₃-containing suspension obtained after the carbonation was aged. Ultrasonic waves were required to generate nanosized vaterite and reducing size at the carbonation stage. This nanosized-vaterite-production strategy involving organic-solvent-free indirect carbonation is meaningful, in that it highlights the potential of synthesizing vaterite in an economically sound, environmentally friendly manner for use as a pharmaceutical raw material.

Enhanced adsorption and colorimetric detection of tetracycline antibiotics by using functional phosphate/carbonate composite with nanoporous network coverage

This work presents efficient tetracycline (TC) antibiotics adsorption using a functional porous phosphate/carbonate composite (PCC). The PCC was fabricated by anion-exchange of phosphate on the surface of vaterite-phase calcium carbonate particle scaffolds. The PCC, having dense nanoporous network coverage with large surface area and pore volume, exhibited excellent TC adsorption in solution. Its adsorption isotherm fitted well to the Freundlich model, with a maximum adsorption capacity of 118.72 mg/g. The adsorption process was spontaneous, endothermic, and followed pseudo-second-order kinetics. From the XPS analysis, the hydrogen bonding and surface complexation were the key interactions in the process. In addition, a colorimetric TC detection method was developed considering its complexation with phosphate ions, originating from PCC dissolution, during adsorption. The method was used to detect TC in mg/L concentrations in water samples. Thus, the multifunctional PCC exhibited potential for use in TC removal and environmental remediation.

Antibacterial Activity and Cell Viability of Biomimetic Magnesian Calcite Coatings on Biodegradable Mg

Mg is a material of choice for biodegradable implants. The main challenge for using Mg in temporary implants is to provide protective surfaces that mitigate its rapid degradation in biological fluids and also confer sufficient cytocompatibility and bacterial resistance to Mg-coated surfaces. Even though carbonate mineralization is the most important source of biominerals, such as the skeletons and shells of many marine organisms, there has been little success in the controlled growth of carbonate layers by synthetic processes. We present here the formation mechanism, antibacterial activity, and cell viability of magnesian calcite biomimetic coatings grown on biodegradable Mg via a green, one-step route. Cell compatibility assessment showed cell viability higher than 80% after 72 h using fibroblast cells (NCTC, clone L929) and higher than 60% after 72 h using human osteoblast-like cells (SaOS-2); the cells displayed a normal appearance and a density similar to the control sample. Antimicrobial potential evaluation against both Gram-positive (Staphylococcus aureus (ATCC 25923)) and Gram-negative (Pseudomonas aeruginosa (ATCC 27853)) strains demonstrated that the coated samples significantly inhibited bacterial adhesion and biofilm formation compared to the untreated control. Calcite coatings grown on biodegradable Mg by a single coating process showed the necessary properties of cell compatibility and bacterial resistance for application in surface-modified Mg biomaterials for temporary implants.

Next-Generation Colloidal Materials for Ultrasound Imaging Applications

Ultrasound has important applications, predominantly in the field of diagnostic imaging. Presently, colloidal systems such as microbubbles, phase-change emulsion droplets and particle systems with acoustic properties and multiresponsiveness are being developed to address typical issues faced when using commercial ultrasound contrast agents, and to extend the utility of such systems to targeted drug delivery and multimodal imaging. Current technologies and increasing research data on the chemistry, physics and materials science of new colloidal systems are also leading to the development of more complex, novel and application-specific colloidal assemblies with ultrasound contrast enhancement and other properties, which could be beneficial for multiple biomedical applications, especially imaging-guided treatments. In this article, we review recent developments in new colloids with applications that use ultrasound contrast enhancement. This work also highlights the emergence of colloidal materials fabricated from or modified with biologically derived and bio-inspired materials, particularly in the form of biopolymers and biomembranes. Challenges, limitations, potential developments and future directions of these next-generation colloidal systems are also presented and discussed.

Dual-drug delivery system based on the hydrogels of alginate and sodium carboxymethyl cellulose for colorectal cancer treatment

To improve the efficacy of chemotherapy and relieve the pain associated with colorectal cancer, a dual-drug delivery system (DDDS) is proposed. In this system, methotrexate (MTX) loaded CaCO₃ (CaCO₃/MTX) and aspirin (Asp) are co-entrapped in the hydrogels of alginate (Alg) and sodium carboxymethyl cellulose (CMC) crosslinked with Ca²⁺. The hydrogels can protect the anti-cancer drug of MTX from being absorbed in stomach and small intestine and ensure their efficacy at the target site of colorectum. More importantly, dual pH-responsive drug delivery can be achieved by the DDDS. Because the pH varies at small intestine and colorectum of human body, dual pH-responsive delivery of Asp and MTX can be achieved at the two organs, respectively, in response to ambient pH. These finding are of significant importance for medical science and pharmaceutics.

Organic matter affects phosphorus recovery during vivianite crystallization

Vivianite crystallization is a promising route for phosphorus (P) recovery from P-rich wastewater. However, organic matter (OM) in wastewater may influence vivianite formation. In this study, the effects of four representative OMs, glucose, bovine serum albumin (BSA), humic acid (HA) and sodium alginate (SA), on P recovery by vivianite were investigated. The results showed that P recovery efficiency was inhibited by HA and SA, declining by 3.7% and 12.1% under HA (100 mg/L) and SA (800 mg/L), respectively. BSA, HA and SA affected the aggregated form of vivianite crystals. Vivianite particle size decreased in the presence of HA and SA. Subsequent mechanistic exploration indicated that the complexation between the OM and Fe²⁺ was the main cause of P recovery efficiency reduction. The coprecipitation of HA and SA with vivianite could reduce the zeta potential on the crystal surface, resulting in a smaller particle size. The nucleation sites provided by BSA and SA could transfer vivianite from single plate-like agglomerate to multilayer plate-like agglomerate. This study provided a better understanding of P recovery by vivianite from OM-rich wastewater.

Magnetic assisted fluorescence immunoassay for sensitive chloramphenicol detection using carbon dots@CaCO3 nanocomposites

Analytical methods with high sensitivities and short assay times are urgently required for the screening of "zero tolerance" hazardous substances in food. Herein, we propose a fluorescent immunoassay for the highly sensitive and rapid analysis of chloramphenicol (CAP) based on carbon dots (CDs)-encapsulated CaCO₃ nanospheres and magnetic nanoparticles (MNPs). The fluorescent immunoprobes were prepared by coupling the anti-CAP antibodies to carboxymethyl cellulose-functional CDs@CaCO₃ nanospheres. Chitosan-modified MNPs with "core-shell" structures were prepared and then conjugated to the CAP hapten, acting as the nano-carrier and interface for the immunoreaction. With the assistance of MNPs, the established fluorescent immunoassay achieved the sensitive detection of CAP in chicken with a limit of detection of 0.03 μg kg^-1 and recoveries ranging from 83.7%-105.0%. The analysis results of the fluorescent immunoassay were evaluated by the enzyme-linked immunosorbent assay, having a correlation coefficient of 0.981. Our work provides a rapid, facile, and reliable strategy for the highly sensitive analysis of food contaminants based on "green" fluorescent nanoprobes.

Biomimetic synthesis of calcium carbonate under phenylalanine: Control of polymorph and morphology

In biomineralization, organisms have the abilities to produce biominerals with superior properties. One of the most attractive features of biominerals is the presence of the proteins consisting of different contents of amino acids in crystals. In the present work, L-phenylalanine (Phe) was used as an additive for the controllable crystallization of calcium carbonate (CaCO₃). The obtained CaCO₃ crystals were characterized by field emission scanning electron microscopy (SEM), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), elemental analysis and high-resolution transmission electron microscopy (HRTEM). The experimental results suggest that single calcite crystals are formed at low Phe concentrations. High concentrations of Phe inhibit the nucleation and growth of calcite, and promote the formation of vaterite crystals with solid or hollow structures. The morphology and crystal form of CaCO₃ are also significantly affected by the flow rate of CO₂. After that, a possible mechanism (competition mechanism) action of Phe in the formation of CaCO₃ is proposed. Finally, the effects of temperature on the formation of vaterite were determined to explore the growth mechanism of hexagonal vaterite. The work of controlling the preparation of CaCO₃ crystals in the presence of Phe will help us to imitate and learn nature, and bring new insights into understanding bionics. Meanwhile, it provides a new method for the synthesis of CaCO₃ biomaterials with different crystal forms and morphologies.

Ultrasonic-assisted eggshell extract-mediated polymorphic transformation of calcium carbonate

This study aimed to evaluate the combined effects of eggshell extract and ultrasonic irradiation on the polymorphic transformation of calcium carbonate (CaCO₃). In this context, XRD, Raman spectroscopy, SEM, AFM, TGA-FTIR, BET, and zeta potential analysis were used to identify and characterize the different polymorphs of CaCO₃ obtained in the absence and presence of eggshell extract in the media with and without ultrasonic irradiation. The morphology and polymorphic nature of the CaCO₃ crystals were observed to change, which indicated that the eggshell extract and ultrasonication influenced the structure and crystallization of CaCO₃. The structural analysis results indicated that the addition of eggshell extract to the media resulted in the full transformation of calcite to the vaterite polymorph. The results also showed that ultrasonic irradiation had a more significant influence on the BET specific surface area of the crystals compared to the eggshell extract media. Furthermore, a Box-Behnken design with response surface methodology was employed to determine the optimal operating conditions for CaCO₃ crystallization. The effects of stirring rate, extract concentration, and ultrasonic power on the BET surface area were investigated. The results show that the data sufficiently fit the second-order polynomial model. Understanding the eggshell extract-mediated polymorphic transformation with ultrasonic irradiation obtained in this study makes it possible to control the polymorphic formation and modify the product characteristics.

Precipitation and Transformation of Vaterite Calcium Carbonate in the Presence of Some Organic Solvents

In this paper, the production of CaCO₃ particles via the carbonation route in the reaction of CaCl₂ and CO₂, using NH₃ as a promoter of CO₂ absorption, was studied. The solvents used as the reaction media for CaCO₃ precipitation were aqueous solutions of methanol, isopropanol and dimethyl sulfoxide (DMSO), in a concentration range of 0–20% (v/v). It was found that the presence of an organic additive influenced the precipitation rate, the content of vaterite in the obtained product, the morphology and the size of the precipitated CaCO₃ particles, as well as the rate of its transformation into calcite. The presence of all added organic solvents reduced the vaterite concentration in the produced CaCO₃ both at the end of the reaction and after incubation in the reaction medium for 1 h. However, the transformation of vaterite particles into calcite in the tested solutions was slower when the 4 h and 24 h procedures were compared. The interactions of solvents with calcite and vaterite were compared using HPLC tests. DMSO molecules interacted with vaterite particles the most strongly, while the interaction of isopropanol with this polymorph was the weakest. The opposite effect was observed for interactions with calcite particles, and the affinity decreased in the series: isopropanol, methanol, DMSO.

Biomimetic Mineralization of Protein Nanogels for Enzyme Protection

Protein nanogels have found a wide variety of applications, ranging from biocatalysis to drug/protein delivery. However, in practical applications, proteins in nanogels may suffer from enzymic hydrolysis and denaturation. Inspired by the structure and functionalities of the fowl eggshells, biomimetic mineralization of protein nanogels was studied in this research. Protein nanogels with embedded porcine pancreas lipase (PPL) in the cross-linked nanostructures were synthesized through the thiol-disulfide reaction between thiol-functionalized PPL and poly(N-isopropylacrylamide) with pendant pyridyl disulfide groups. The nanogels were further reacted with reduced bovine serum albumin (BSA) and BSA molecules were coated on the nanogels. Mineralization of BSA leads to the synthesis of biomineralized shells on the nanogels. With the growth of CaCO₃ on the shells, the nanogels aggregate into suprastructures. Thermogravimetric analysis, XRD, dynamic light scattering, and TEM were employed to study the mechanism of the biomineralization process and analyze the structures of the mineralized nanogels. The biomineralized shells can effectively protect the PPL molecules from hydrolysis by trypsin; meanwhile, the nanosized channels on the mineralized shells allow the transport of small-molecule substrates across the shells. Bioactivity measurements indicate that PPL in the nanogels maintains more than 80 % bioactivity after biomineralization.

Application of Different Fourier Transform Infrared (FT-IR) Methods in the Characterization of Lime-Based Mortars with Oxblood

Organic compounds have frequently been added into lime mortars for property modifications, in order to satisfy various functional needs in building techniques. This study applies Fourier transform infrared (FT-IR) spectroscopy in transmission, reflection, and attenuated total reflection (ATR) modes to characterize lime-based mortar specimens containing oxblood, which has been used as additive as a common practice of long history in many parts of the world. The specimens were prepared basing upon a 19th-century Italian historic recipe, with the intention to have a better understanding on the possible characteristics of such mortars. Thermal analysis, color measurement, and static contact angle test were also used. After curing, the specimens show a distinctive dark-red color on the top surface, which is different from the bulk. Color measurements on the surface suggest that this color was formed at an early stage and was able to maintain stable for a relatively long period of time. Both transmission and reflection FT-IR confirm the preferential accumulation of proteins on the top surface, which should have induced their water repellency according to the static contact angle test. In addition, specimens show weaker calcite bands in FT-IR transmission, reflection, as well as ATR spectra; the pattern of ATR spectra after the thermal analysis to 500 °C suggests the formation of amorphous calcium carbonate, which is related to the presence of oxblood.

Synthesis Methods and Favorable Conditions for Spherical Vaterite Precipitation: A Review

Vaterite is the least thermodynamically stable anhydrous calcium carbonate polymorph. Its existence is very rare in nature, e.g., in some rock formations or as a component of biominerals produced by some fishes, crustaceans, or birds. Synthetic vaterite particles are proposed as carriers of active substances in medicines, additives in cosmetic preparations as well as adsorbents. Also, their utilization as a pump for microfluidic flow is also tested. In particular, vaterite particles produced as polycrystalline spheres have large potential for application. Various methods are proposed to precipitate vaterite particles, including the conventional solution-solution synthesis, gas-liquid method as well as special routes. Precipitation conditions should be carefully selected to obtain a high concentration of vaterite in all these methods. In this review, classical and new methods used for vaterite precipitation are presented. Furthermore, the key parameters affecting the formation of spherical vaterite are discussed.

Influence of Selected Saccharides on the Precipitation of Calcium-Vaterite Mixtures by the CO2 Bubbling Method

Calcium carbonate is a compound existing in living organisms and produced for many biomedical applications. In this work, calcium carbonate was synthesized by a CO2 bubbling method using ammonia as a CO2 absorption promotor. Glucose, fructose, sucrose, and trehalose were added into the reaction mixture to modify characteristics of precipitated calcium carbonate particles. To determine the polymorphic form of produced calcium carbonate particles, Fourier transform infrared spectroscopy (FTIR-ATR) and X-ray diffraction (XRD) analysis were performed. Scanning electron microscopy (SEM) was used to estimate the size and shape of produced particles. Mixtures of vaterite and calcite were synthesized in all experiments. The percentage content of the vaterite in the samples depended on used additive. The highest concentration of vaterite (90%) was produced from a solution containing sucrose, while the lowest concentration (2%) was when fructose was added. Saccharides affected the rate of CO2 absorption, which resulted in a change in the precipitation rate and, therefore, the polymorphic composition of calcium carbonate obtained in the presence of saccharides was more varied.

Mineralized calcium carbonate/xanthan gum microspheres for lysozyme adsorption

Calcium carbonate/xanthan gum (Ca₂CO₃/XG) microspheres were prepared using biomimetic mineralization method for lysozyme (Ly) adsorption. The morphology of Ca₂CO₃/XG microspheres was characterized by field emission scanning electron microscope (FE-SEM). The Ly adsorption behavior was verified by Fourier transform infrared (FTIR) and in situ fluorescence microscope images. The effects of pHs on lysozyme adsorption were investigated as well. It was revealed that CaCO₃/XG microspheres could immobilize lysozyme efficiently via electrostatic interactions with adsorption rate and adsorption quantity of 58.55 ± 0.56% and 18.7 ± 1.2 μg/mg as the pH was 7.0. Comparatively, the values markedly improved to 80.97 ± 0.15% and 24.3 ± 0.1 μg/mg respectively as the pH was 9.0 (p < 0.05). Additionally, UV and fluorescence spectrum showed that Ly maintained its original secondary structure during the adsorption/desorption process. The study therefore demonstrated that CaCO₃/XG microspheres can be used as a practical and efficient support for Ly adsorption and desorption.

A trypsin–calcium carbonate hybrid nanosphere based enzyme reactor with good stability and reusability

Trypsin not only acts as a novel robust biotemplate to mediate the growth of CaCO₃ crystals, but also enhances their biological properties as an excellent enzyme.