Polydopamine coating of living diatom microalgae.

Many microorganisms produce specific structures, known as spores or cysts, to increase their resistance to adverse environmental conditions. Scientists have started to produce biomimetic materials inspired by these natural membranes, especially for industrial and biomedical applications. Here, we present biological data on the biocompatibility of a polydopamine-based artificial coating for diatom cells. In this work, living Thalassiosira weissflogii diatom cells are coated on their surface with a polydopamine layer mimicking mussel adhesive protein. Polydopamine does not affect diatoms growth kinetics, it enhances their resistance to degradation by treatment with detergents and acids, and it decreases the uptake of model staining emitters. These outcomes pave the way for the use of living diatom cells bearing polymer coatings for sensors based on living cells, resistant to artificial microenvironments, or acting as living devices for cells interface study.

In vivo functionalization of diatom biosilica with sodium alendronate as osteoactive material.

Bisphosphonates are a class of drugs widely used in the clinical treatment of disorders of bone metabolism, such as osteoporosis, fibrous dysplasia, myeloma and bone metastases. Because of the negative side effects caused by oral administration of bisphosphonates, various silica mesoporous materials have been investigated for a confined and controlled release of these drugs. Here, we propose biosilica from diatoms as suitable substrate for alendronate local activation of bone cells. Following a novel strategy, sodium alendronate can be in vivo incorporated into biosilica shells of cultured Thalassiosira weissflogii diatoms, by feeding the algae with an aqueous solution of the drug. After acid/oxidative treatments for removing organic matter, the resulting bisphosphonate-functionalized mesoporous biosilica was characterized and tested as osteoinductive support. Effects on osteoblast growth and anti-osteoclast activity have been examined by evaluating SaOS-2, BMSC, J774 cell viability on the alendronate-"doped" biosilica. The loading percentage of sodium alendronate into biosilica, estimated as 1.45% w/w via TGA, was able to decrease metabolic activity of J774 osteoclasts-like cells till 5% over glass control. We demonstrated a good osteoconductive ability and activation of a tissue regeneration model together with osteoclasts inhibition of the functionalized biosilica, opening the way to interesting applications for diatom microalgae as a bioinspired mesoporous material for tissue engineering.

Data from in vivo functionalization of diatom mesoporous biosilica with bisphosphonates.

Diatoms are unicellular photosynthetic microalgae that produce a sophisticated mesoporous biosilica shell called frustule. Easy to achieve and extract, diatom frustules represent a low-cost source of mesoporous biocompatible biosilica. In this paper, the possibility to in vivo functionalize the diatom biosilica with bisphosphonates (BPs) was investigated. In particular, two BPs were tested: the amino-containing sodium alendronate (ALE) and the amino-lacking sodium etidronate (ETI). According to first SEM-EDX analysis, the presence of the amino-moiety in ALE structure allowed a better incorporation of this BP into living diatom biosilica, compared to ETI. Then, diatom growth was deeply investigated in presence of ALE. After extraction of functionalized frustules, ALE-biosilica was further characterized by XPS and microscopy, and ALE release was evaluated by ferrochelation assay. Moreover, the bone regeneration performances of ALE-functionalized frustules were preliminarily investigated on bone osteoblast-like cells, via Comassie staining. Data are related to the research article "In vivo functionalization of diatom biosilica with sodium alendronate as osteoactive material".

Multiple Routes to Smart Nanostructured Materials from Diatom Microalgae: A Chemical Perspective.

Diatoms are unicellular photosynthetic microalgae, ubiquitously diffused in both marine and freshwater environments, which exist worldwide with more than 100 000 species, each with different morphologies and dimensions, but typically ranging from 10 to 200 µm. A special feature of diatoms is their production of siliceous micro- to nanoporous cell walls, the frustules, whose hierarchical organization of silica layers produces extraordinarily intricate pore patterns. Due to the high surface area, mechanical resistance, unique optical features, and biocompatibility, a number of applications of diatom frustules have been investigated in photonics, sensing, optoelectronics, biomedicine, and energy conversion and storage. Current progress in diatom-based nanotechnology relies primarily on the availability of various strategies to isolate frustules, retaining their morphological features, and modify their chemical composition for applications that are not restricted to those of the bare biosilica produced by diatoms. Chemical or biological methods that decorate, integrate, convert, or mimic diatoms' biosilica shells while preserving their structural features represent powerful tools in developing scalable, low-cost routes to a wide variety of nanostructured smart materials. Here, the different approaches to chemical modification as the basis for the description of applications relating to the different materials thus obtained are presented.

Highly Sensitive and Practical Detection of Plant Viruses via Electrical Impedance of Droplets on Textured Silicon-Based Devices.

Early diagnosis of plant virus infections before the disease symptoms appearance may represent a significant benefit in limiting disease spread by a prompt application of appropriate containment steps. We propose a label-free procedure applied on a device structure where the electrical signal transduction is evaluated via impedance spectroscopy techniques. The device consists of a droplet suspension embedding two representative purified plant viruses i.e., Tomato mosaic virus and Turnip yellow mosaic virus, put in contact with a highly hydrophobic plasma textured silicon surface. Results show a high sensitivity of the system towards the virus particles with an interestingly low detection limit, from tens to hundreds of attomolar corresponding to pg/mL of sap, which refers, in the infection time-scale, to a concentration of virus particles in still-symptomless plants. Such a threshold limit, together with an envisaged engineering of an easily manageable device, compared to more sophisticated apparatuses, may contribute in simplifying the in-field plant virus diagnostics.

Data from two different culture conditions of Thalassiosira weissflogii diatom and from cleaning procedures for obtaining monodisperse nanostructured biosilica.

Diatoms microalgae produce biosilica nanoporous rigid outershells called frustules that exhibit an intricate nanostructured pore pattern. In this paper two specific Thalassiosira weissflogii culture conditions and size control procedures during the diatoms growth are described. Data from white field and fluorescence microscopy, evaluation of cell densities and cell parameters (k value and R value) according to cell culture conditions are listed. Different cleaning procedures for obtaining bare frustules are described. In addition, FTIR and spectrofluorimetric analyses of cleaned biosilica are shown. The data are related to the research article "Chemically Modified Diatoms Biosilica for Bone Cell Growth with Combined Drug-Delivery and Antioxidant Properties" [1].

Chemically Modified Diatoms Biosilica for Bone Cell Growth with Combined Drug-Delivery and Antioxidant Properties.

This month's cover is dedicated to the joint project coordinated by Prof. Gianluca M. Farinola involving the Università degli Studi di Bari Aldo Moro, CNR ICCOM and IMIP in Bari, Università Politecnica delle Marche, and Jaber Innovation. The cover picture shows an SEM image of nanostructured biosilica produced by- Thalassiosira weissflogii- diatoms covalently functionalized with the radical scavenger TEMPO (green disks) and loaded with the antibiotic Ciprofloxacin (red/white capsules), which is used to combat infections related to orthopedic implants. Read the full text of the article at 10.1002/cplu.201402398.

Chemically Modified Diatoms Biosilica for Bone Cell Growth with Combined Drug-Delivery and Antioxidant Properties.

Nanostructured biosilica produced by Thalassiosira weissflogii diatoms is covalently functionalized with the cyclic nitroxide 2,6,6-tetramethylpiperidine-N-oxyl (TEMPO), an efficient scavenger of reactive oxygen species (ROS) in biological systems. Drug delivery properties of the TEMPO-functionalized biosilica are studied for Ciprofloxacin, an antimicrobial thoroughly employed in orthopedic or dental implant related infections. The resulting TEMPO-biosilica, combining Ciprofloxacin drug delivery with anti-oxidant properties, is demonstrated to be a suitable material for fibroblasts and osteoblast-like cells growth.

A novel cyclization reaction between 2,3-bis(trimethylsilyl)buta-1,3-diene and acyl chlorides with straightforward formation of polysubstituted furans.

A novel cyclization process of 2,3-bis(trimethylsilyl)buta-1,3-diene with various acyl chlorides in the presence of aluminium trichloride affords 2,5-disubstituted or 2,3,5-trisubstituted furans in short reaction time; a subsequent acylation process of the furan ring occurs if the reaction time is prolonged.