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Fabrication and applications of bioactive chitosan-based organic-inorganic hybrid materials: A review.
Liu, X, Wu, Y, Zhao, X, Wang, Z
Carbohydrate polymers. 2021;:118179
Abstract
Organic-inorganic hybrid materials like bone, shells, and teeth can be found in nature, which are usually composed of biomacromolecules and nanoscale inorganic ingredients. Synergy of organic-inorganic components in hybrid materials render them outstanding and versatile performance. Chitosan is commonly used organic materials in bionic hybrid materials since its bioactive properties and could be controllable tailored by various means to meet complex conditions in different applications. Among these fabrication means, hybridization was favored for its convenience and efficiency. This review discusses three kinds of chitosan-based hybrid materials: hybridized with hydroxyapatite, calcium carbonate, and clay respectively, which are the representative of phosphate, carbonate, and hydrous aluminosilicates. Here, we reported the latest developments of the preparation methods, composition, structure and applications of these bioactive hybrid materials, especially in the biomedical field. Despite the great progress was made in bioactive organic-inorganic hybrid materials based on chitosan, some challenges and specific directions are still proposed for future development in this review.
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Environmental safety and biosafety in construction biotechnology.
Ivanov, V, Stabnikov, V, Stabnikova, O, Kawasaki, S
World journal of microbiology & biotechnology. 2019;(2):26
Abstract
The topics of Construction Biotechnology are the development of construction biomaterials and construction biotechnologies for soil biocementation, biogrouting, biodesaturation, bioaggregation and biocoating. There are known different biochemical types of these biotechnologies. The most popular construction biotechnology is based on precipitation of calcium carbonate initiated by enzymatic hydrolysis of urea which follows with release of ammonia and ammonium to environment. This review focuses on the hazards and remedies for construction biotechnologies and on the novel environmentally friendly biotechnologies based on precipitation of hydroxyapatite, decay of calcium bicarbonate, and aerobic oxidation of calcium salts of organic acids. The use of enzymes or not living bacteria are the best options to ensure biosafety of construction biotechnologies. Only environmentally safe construction biotechnologies should be used for such environmental and geotechnical engineering works as control of the seepage in dams, channels, landfills or tunnels, sealing of the channels and the ponds, prevention of soil erosion and soil dust emission, mitigation of soil liquefaction, and immobilization of soil pollutants.
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Microbially induced calcium carbonate precipitation: a widespread phenomenon in the biological world.
Seifan, M, Berenjian, A
Applied microbiology and biotechnology. 2019;(12):4693-4708
Abstract
Biodeposition of minerals is a widespread phenomenon in the biological world and is mediated by bacteria, fungi, protists, and plants. Calcium carbonate is one of those minerals that naturally precipitate as a by-product of microbial metabolic activities. Over recent years, microbially induced calcium carbonate precipitation (MICP) has been proposed as a potent solution to address many environmental and engineering issues. However, for being a viable alternative to conventional techniques as well as being financially and industrially competitive, various challenges need to be overcome. In this review, the detailed metabolic pathways, including ammonification of amino acids, dissimilatory reduction of nitrate, and urea degradation (ureolysis), along with the potent bacteria and the favorable conditions for precipitation of calcium carbonate, are explained. Moreover, this review highlights the potential environmental and engineering applications of MICP, including restoration of stones and concrete, improvement of soil properties, sand consolidation, bioremediation of contaminants, and carbon dioxide sequestration. The key research and development questions necessary for near future large-scale applications of this innovative technology are also discussed.
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4.
Exploiting algal mineralization for nanotechnology: bringing coccoliths to the fore.
Skeffington, AW, Scheffel, A
Current opinion in biotechnology. 2018;:57-63
Abstract
Complex mineral structures are produced by many microalgal species. Pioneering work on diatom silica has demonstrated the potential of such structures in nanotechnology. The calcified scales of coccolithophores (coccoliths) have received less attention, but the large diversity of architectures make coccoliths attractive as parts for nano-devices. Currently coccolith calcite can be modified by the incorporation of metal ions or adsorption of enzymes to the surface, but genetic modification of coccolithophores may permit the production of coccoliths with customized architectures and surface properties. Further work on the laboratory cultivation of diverse species, the physiochemical properties of coccoliths and on genetic tools for coccolithophores will be necessary to realize the full potential of coccoliths in nanotechnology.
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5.
Current challenges and future directions for bacterial self-healing concrete.
Lee, YS, Park, W
Applied microbiology and biotechnology. 2018;(7):3059-3070
Abstract
Microbially induced calcium carbonate precipitation (MICP) has been widely explored and applied in the field of environmental engineering over the last decade. Calcium carbonate is naturally precipitated as a byproduct of various microbial metabolic activities. This biological process was brought into practical use to restore construction materials, strengthen and remediate soil, and sequester carbon. MICP has also been extensively examined for applications in self-healing concrete. Biogenic crack repair helps mitigate the high maintenance costs of concrete in an eco-friendly manner. In this process, calcium carbonate precipitation (CCP)-capable bacteria and nutrients are embedded inside the concrete. These bacteria are expected to increase the durability of the concrete by precipitating calcium carbonate in situ to heal cracks that develop in the concrete. However, several challenges exist with respect to embedding such bacteria; harsh conditions in concrete matrices are unsuitable for bacterial life, including high alkalinity (pH up to 13), high temperatures during manufacturing processes, and limited oxygen supply. Additionally, many biological factors, including the optimum conditions for MICP, the molecular mechanisms involved in MICP, the specific microorganisms suitable for application in concrete, the survival characteristics of the microorganisms embedded in concrete, and the amount of MICP in concrete, remain unclear. In this paper, metabolic pathways that result in conditions favorable for calcium carbonate precipitation, current and potential applications in concrete, and the remaining biological challenges are reviewed.
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6.
Microbial healing of cracks in concrete: a review.
Joshi, S, Goyal, S, Mukherjee, A, Reddy, MS
Journal of industrial microbiology & biotechnology. 2017;(11):1511-1525
Abstract
Concrete is the most widely used construction material of the world and maintaining concrete structures from premature deterioration is proving to be a great challenge. Early age formation of micro-cracking in concrete structure severely affects the serviceability leading to high cost of maintenance. Apart from conventional methods of repairing cracks with sealants or treating the concrete with adhesive chemicals to prevent the cracks from widening, a microbial crack-healing approach has shown promising results. The unique feature of the microbial system is that it enables self-healing of concrete. The effectiveness of microbially induced calcium carbonate precipitation (MICCP) in improving durability of cementitious building materials, restoration of stone monuments and soil bioclogging is discussed. Main emphasis has been laid on the potential of bacteria-based crack repair in concrete structure and the applications of different bacterial treatments to self-healing cracks. Furthermore, recommendations to employ the MICCP technology at commercial scale and reduction in the cost of application are provided in this review.
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7.
Bioconcrete: next generation of self-healing concrete.
Seifan, M, Samani, AK, Berenjian, A
Applied microbiology and biotechnology. 2016;(6):2591-602
Abstract
Concrete is one of the most widely used construction materials and has a high tendency to form cracks. These cracks lead to significant reduction in concrete service life and high replacement costs. Although it is not possible to prevent crack formation, various types of techniques are in place to heal the cracks. It has been shown that some of the current concrete treatment methods such as the application of chemicals and polymers are a source of health and environmental risks, and more importantly, they are effective only in the short term. Thus, treatment methods that are environmentally friendly and long-lasting are in high demand. A microbial self-healing approach is distinguished by its potential for long-lasting, rapid and active crack repair, while also being environmentally friendly. Furthermore, the microbial self-healing approach prevails the other treatment techniques due to the efficient bonding capacity and compatibility with concrete compositions. This study provides an overview of the microbial approaches to produce calcium carbonate (CaCO3). Prospective challenges in microbial crack treatment are discussed, and recommendations are also given for areas of future research.
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8.
Microbially-induced Carbonate Precipitation for Immobilization of Toxic Metals.
Kumari, D, Qian, XY, Pan, X, Achal, V, Li, Q, Gadd, GM
Advances in applied microbiology. 2016;:79-108
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Abstract
Rapid urbanization and industrialization resulting from growing populations contribute to environmental pollution by toxic metals and radionuclides which pose a threat to the environment and to human health. To combat this threat, it is important to develop remediation technologies based on natural processes that are sustainable. In recent years, a biomineralization process involving ureolytic microorganisms that leads to calcium carbonate precipitation has been found to be effective in immobilizing toxic metal pollutants. The advantage of using ureolytic organisms for bioremediating metal pollution in soil is their ability to immobilize toxic metals efficiently by precipitation or coprecipitation, independent of metal valence state and toxicity and the redox potential. This review summarizes current understanding of the ability of ureolytic microorganisms for carbonate biomineralization and applications of this process for toxic metal bioremediation. Microbial metal carbonate precipitation may also be relevant to detoxification of contaminated process streams and effluents as well as the production of novel carbonate biominerals and biorecovery of metals and radionuclides that form insoluble carbonates.
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9.
Hypocalcaemia following thyroidectomy unresponsive to oral therapy.
Etheridge, ZC, Schofield, C, Prinsloo, PJ, Sturrock, ND
Hormones (Athens, Greece). 2014;(2):286-9
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Abstract
Hypocalcaemia due to hypoparathyroidism following thyroidectomy is a relatively common occurrence. Standard treatment is with oral calcium and vitamin D replacement therapy; lack of response to oral therapy is rare. Herein we describe a case of hypoparathyroidism following thyroidectomy unresponsive to oral therapy in a patient with a complex medical history. We consider the potential causes in the context of calcium metabolism including: poor adherence, hungry bone syndrome, malabsorption, vitamin D resistance, bisphosphonate use and functional hypoparathyroidism secondary to magnesium deficiency. Malabsorption due to intestinal hurry was likely to be a contributory factor in this case and very large doses of oral therapy were required to avoid symptomatic hypocalcaemia.
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10.
The development and validation of a new technology, based upon 1.5% arginine, an insoluble calcium compound and fluoride, for everyday use in the prevention and treatment of dental caries.
Cummins, D
Journal of dentistry. 2013;:S1-11
Abstract
OBJECTIVE This paper briefly discusses caries prevalence, the multi-factorial nature of caries etiology, caries risk and the role and efficacy of fluoride. The paper also highlights research on bacterial metabolism which provided understanding of the mouth's natural defenses against caries and the basis for the development of a new technology for the everyday prevention and treatment of caries. Finally, evidence that the technology complements and enhances the anti-caries efficacy of fluoride toothpaste is summarized. CONCLUSIONS Global data show that dental caries is a prevalent disease, despite the successful introduction of fluoride. Caries experience depends on the balance between consumption of sugars and oral hygiene and the use of fluoride. Three scientific concepts are fundamental to new measures to detect, treat and monitor caries: (1) dental caries is a dynamic process, (2) dental caries is a continuum of stages from reversible, pre-clinical to irreversible, clinically detectable lesions, and (3) the caries process is a balance of pathological and protective factors that can be modulated to manage caries. Fluoride functions as a protective factor by arresting and reversing the caries process, but fluoride does not prevent pathological factors that initiate the process. A novel technology, based upon arginine and an insoluble calcium compound, has been identified which targets dental plaque to prevent initiation of the caries process by reducing pathological factors. As the mechanisms of action of arginine and fluoride are highly complementary, a new dentifrice, which combines arginine with fluoride, has been developed and clinically proven to provide superior caries prevention.