Fabrication of fluorescent microparticles by doping water-soluble CdTe nanocrystals into calcium carbonate for monitoring intracellular uptake

A comprehensive review of recent advancements in microbial-induced mineralization: biosynthesis and mechanism, with potential implementation in various environmental, engineering, and medical sectors

Biomineralization has garnered profuse attention in multidisciplinary fields. Using this strategy, living things, including eukaryotes or prokaryotes, mediate the uptake of ions from the surrounding environment, followed by assembling and depositing them as greatly configured structures inside the organic matrix. The generated biominerals, including nanomaterials, possess outstanding hierarchical structures that exceed their chemically synthesized counterparts. Despite the significant progress achieved in microbial-mediated mineralization, several key knowledge gaps remain, including mechanisms controlling biomineralization pathways and the impact of environmental factors on mineral morphology, crystallinity, and stability. This review provides a comprehensive description of this biomineralization, which can be categorized into controlled, influenced, and induced biomineralization. Interestingly, we highlighted biologically-induced mineralization approaches, such as photosynthesis, methane oxidation, and nitrogen-based metabolic pathways, and identified various chemical interactions during mineral production following analytical chemistry. This review also extensively delineates updates on application of biominerals across all fields, commencing with the remediation of deleterious pollutants and biominerals exploited in industrial sectors, moving on to using them to reinforce soil, generate biocement for construction, and delving into their utilization in pharmaceutical applications to deliver drugs, repair teeth and bones, and combat cancer and pathogenic microorganisms. Moreover, the review outlines the drawbacks and adequate solutions for biomineralization, particularly CaCO₃-mediated processes, such as the generation of ammonium and nitrate during the CaCO₃ precipitation process and the relatively slow rate of microbial-mediated mineralization. Biomineralization inspired the fabrication of smart biomaterials, which combine biological advantages. Overall, this comprehensive review discusses updated research and highlights potential approaches to future studies.

Formations of calcium carbonate minerals by bacteria and its multiple applications

Biomineralization is a naturally occurring process in living organisms. In this review, we discuss microbially induced calcium carbonate precipitation (MICP) in detail. In the MICP process, urease plays a major role in urea hydrolysis by a wide variety of microorganisms capable of producing high levels of urease. We also elaborate on the different polymorphs and the role of calcium in the formation of calcite crystal structures using various calcium sources. Additionally, the environmental factors affecting the production of urease and carbonate precipitation are discussed. This MICP is a promising, eco-friendly alternative approach to conventional and current remediation technologies to solve environmental problems in multidisciplinary fields. Multiple applications of MICP such as removal of heavy metals and radionuclides, improve the quality of construction materials and sequestration of atmospheric CO₂ are discussed. In addition, we discuss other applications such as removal of calcium ions, PCBs and use of filler in rubber and plastics and fluorescent particles in stationary ink and stationary markers. MICP technology has become an efficient aspect of multidisciplinary fields. This report not only highlights the major strengths of MICP, but also discusses the limitations to application of this technology on a commercial scale.

Bioinspired synthesis of fluorescent calcium carbonate/carbon dot hybrid composites

Herein, we report a novel method to synthesise fluorescent calcium carbonate/carbon dots (CaCO3/CDs) by simply mixing CaCl2 and Na2CO3 solutions in the presence of CDs. There are two roles of CDs in this easy and cost-effective biomimetic strategy, that is as the template to direct the formation and assembly of calcite nanocrystals into hierarchical spheres with diameters in the range of 200-300 nm and simultaneously as the phosphor to enable the CaCO3 to emit blue fluorescence under UV (365 nm) irradiation with a quantum yield of 56.2%. The CaCO3/CD hybrid composites possessing unique fluorescence properties are potentially useful in various applications.

Catalytic biomineralization of fluorescent calcite by the thermophilic bacterium Geobacillus thermoglucosidasius

The thermophilic Geobacillus bacterium catalyzed the formation of 100-μm hexagonal crystals at 60°C in a hydrogel containing sodium acetate, calcium chloride, and magnesium sulfate. Under fluorescence microscopy, crystals fluoresced upon excitation at 365 ± 5, 480 ± 20, or 545 ± 15 nm. X-ray diffraction indicated that the crystals were magnesium-calcite in calcite-type calcium carbonate.