https://pubs.rsc.org/en/content/articlepdf/2019/NP/C8NP00092A

Marine natural products.

Rapid synthesis of Au, Ag, and bimetallic Au core-Ag shell nanoparticles using Neem (Azadirachta indica) leaf broth.

Based on fundamental chemistry, biotechnology and materials science have developed over the past three decades into today's powerful disciplines which allow the engineering of advanced technical devices and the industrial production of active substances for pharmaceutical and biomedical applications. This review is focused on current approaches emerging at the intersection of materials research, nanosciences, and molecular biotechnology. This novel and highly interdisciplinary field of chemistry is closely associated with both the physical and chemical properties of organic and inorganic nanoparticles, as well as to the various aspects of molecular cloning, recombinant DNA and protein technology, and immunology. Evolutionary optimized biomolecules such as nucleic acids, proteins, and supramolecular complexes of these components, are utilized in the production of nanostructured and mesoscopic architectures from organic and inorganic materials. The highly developed instruments and techniques of today's materials research are used for basic and applied studies of fundamental biological processes.

/pdf/nanoparticles-proteins-and-nucleic-acids-biotechnology-meets-4nzdmnwi4l.pdf

Nanoparticles, Proteins, and Nucleic Acids: Biotechnology Meets Materials Science

Diatoms are unicellular algae with plastids acquired by secondary endosymbiosis. They are responsible for approximately 20% of global carbon fixation. We report the 34 million-base pair draft nuclear genome of the marine diatom Thalassiosira pseudonana and its 129 thousand-base pair plastid and 44 thousand-base pair mitochondrial genomes. Sequence and optical restriction mapping revealed 24 diploid nuclear chromosomes. We identified novel genes for silicic acid transport and formation of silica-based cell walls, high-affinity iron uptake, biosynthetic enzymes for several types of polyunsaturated fatty acids, use of a range of nitrogenous compounds, and a complete urea cycle, all attributes that allow diatoms to prosper in aquatic environments.

/pdf/the-genome-of-the-diatom-thalassiosira-pseudonana-ecology-2hwz6jrxaw.pdf

The Genome of the Diatom Thalassiosira Pseudonana: Ecology, Evolution, and Metabolism

Immobilization is often the key to optimizing the operational performance of an enzyme in industrial processes, particularly for use in non-aqueous media. Different methods for the immobilization of enzymes are critically reviewed. The methods are divided into three main categories, viz. (i) binding to a prefabricated support (carrier), (ii) entrapment in organic or inorganic polymer matrices, and (iii) cross-linking of enzyme molecules. Emphasis is placed on relatively recent developments, such as the use of novel supports, e.g., mesoporous silicas, hydrogels, and smart polymers, novel entrapment methods and cross-linked enzyme aggregates (CLEAs).

http://largens.com/biochemlab/peroxidase2.pdf

Enzyme immobilization: The quest for optimum performance

Diatom cell walls are regarded as a paradigm for controlled production of nanostructured silica, but the mechanisms allowing biosilicification to proceed at ambient temperature at high rates have remained enigmatic. A set of polycationic peptides (called silaffins) isolated from diatom cell walls were shown to generate networks of silica nanospheres within seconds when added to a solution of silicic acid. Silaffins contain covalently modified lysine-lysine elements. The first lysine bears a polyamine consisting of 6 to 11 repeats of the N-methyl-propylamine unit. The second lysine was identified as epsilon-N,N-dimethyl-lysine. These modifications drastically influence the silica-precipitating activity of silaffins.

http://science.sciencemag.org/content/sci/286/5442/1129.full.pdf

Polycationic Peptides from Diatom Biosilica That Direct Silica Nanosphere Formation

Silaffins are uniquely modified peptides that have been implicated in the biogenesis of diatom biosilica. A method that avoids the harsh anhydrous hydrogen fluoride treatment commonly used to dissolve biosilica allows the extraction of silaffins in their native state. The native silaffins carry further posttranslational modifications in addition to their polyamine moieties. Each serine residue was phosphorylated, and this high level of phosphorylation is essential for biological activity. The zwitterionic structure of native silaffins enables the formation of supramolecular assemblies. Time-resolved analysis of silica morphogenesis in vitro detected a plastic silaffin-silica phase, which may represent a building material for diatom biosilica.

https://science.sciencemag.org/content/sci/298/5593/584.full.pdf

Self-Assembly of Highly Phosphorylated Silaffins and Their Function in Biosilica Morphogenesis

Biomineralizing organisms use organic molecules to generate species-specific mineral patterns. Here, we describe the chemical structure of long-chain polyamines (up to 20 repeated units), which represent the main organic constituent of diatom biosilica. These substances are the longest polyamine chains found in nature and induce rapid silica precipitation from a silicic acid solution. Each diatom is equipped with a species-specific set of polyamines and silica-precipitating proteins, which are termed silaffins. Different morphologies of precipitating silica can be generated by polyamines of different chain lengths as well as by a synergistic action of long-chain polyamines and silaffins.

https://www.pnas.org/content/pnas/97/26/14133.full.pdf

Species-specific polyamines from diatoms control silica morphology

The stunning silica structures formed by diatoms are among the most remarkable examples of biological nanofabrication. In recent years, insight into the molecules and mechanism that allow diatoms to perform silica morphogenesis under ambient conditions has been gained.

/pdf/silica-formation-in-diatoms-the-function-of-long-chain-2eyx51eykz.pdf

Silica formation in diatoms: the function of long-chain polyamines and silaffins

Diatoms are eukaryotic, unicellular algae that are ubiquitously present in almost any water habitat on earth Diatoms dominate phytoplankton populations and algal blooms in the oceans They are responsible for about 25 % of the world's net primary production Apart from this ecological significance, diatoms are mainly known for the intricate geometries and spectacular patterns of their silica-based cell walls These patterns are species specific They are precisely reproduced in each generation documenting a genetic control of this biomineralization process Biogenesis of the diatom cell wall is considered to be a paradigm for the controlled production of nanostructured silica Biochemical studies demonstrated that diatom biosilica is a composite material containing zwitterionic proteins (silaffins) and long-chain polyamines in addition to silica Functional studies indicate a crucial role of these organic components in guiding silica precipitation as well as in the formation of species-specific nanopatterns These activities can be explained by molecular self-assembly and phase-separation processes Moreover, diatom cell walls also exhibit very exciting properties from the physical point of view: they are extremely stable and they may act as photonic crystals

Manfred Sumper

Papers

Polycationic Peptides from Diatom Biosilica That Direct Silica Nanosphere Formation

Self-Assembly of Highly Phosphorylated Silaffins and Their Function in Biosilica Morphogenesis

Species-specific polyamines from diatoms control silica morphology

Silica formation in diatoms: the function of long-chain polyamines and silaffins

Learning from Diatoms: Nature's Tools for the Production of Nanostructured Silica