Panchanathan Manivasagan

Alginate composites for bone tissue engineering: A review

Bone is a complex and hierarchical tissue consisting of nano hydroxyapatite and collagen as major portion. Several attempts have been made to prepare the artificial bone so as to replace the autograft and allograft treatment. Tissue engineering is a promising approach to solve the several issues and is also useful in the construction of artificial bone with materials including polymer, ceramics, metals, cells and growth factors. Composites consisting of polymer-ceramics, best mimic the natural functions of bone. Alginate, an anionic polymer owing enormous biomedical applications, is gaining importance particularly in bone tissue engineering due to its biocompatibility and gel forming properties. Several composites such as alginate-polymer (PLGA, PEG and chitosan), alginate-protein (collagen and gelatin), alginate-ceramic, alginate-bioglass, alginate-biosilica, alginate-bone morphogenetic protein-2 and RGD peptides composite have been investigated till date. These alginate composites show enhanced biochemical significance in terms of porosity, mechanical strength, cell adhesion, biocompatibility, cell proliferation, alkaline phosphatase increase, excellent mineralization and osteogenic differentiation. Hence, alginate based composite biomaterials will be promising for bone tissue regeneration. This review will provide a broad overview of alginate preparation and its applications towards bone tissue engineering.

Pharmaceutically active secondary metabolites of marine actinobacteria.

Marine actinobacteria are one of the most efficient groups of secondary metabolite producers and are very important from an industrial point of view. Many representatives of the order Actinomycetales are prolific producers of thousands of biologically active secondary metabolites. Actinobacteria from terrestrial sources have been studied and screened since the 1950s, for many important antibiotics, anticancer, antitumor and immunosuppressive agents. However, frequent rediscovery of the same compounds from the terrestrial actinobacteria has made them less attractive for screening programs in the recent years. At the same time, actinobacteria isolated from the marine environment have currently received considerable attention due to the structural diversity and unique biological activities of their secondary metabolites. They are efficient producers of new secondary metabolites that show a range of biological activities including antibacterial, antifungal, anticancer, antitumor, cytotoxic, cytostatic, anti-inflammatory, anti-parasitic, anti-malaria, antiviral, antioxidant, anti-angiogenesis, etc. In this review, an evaluation is made on the current status of research on marine actinobacteria yielding pharmaceutically active secondary metabolites. Bioactive compounds from marine actinobacteria possess distinct chemical structures that may form the basis for synthesis of new drugs that could be used to combat resistant pathogens. With the increasing advancement in science and technology, there would be a greater demand for new bioactive compounds synthesized by actinobacteria from various marine sources in future.

Brown seaweed fucoidan: biological activity and apoptosis, growth signaling mechanism in cancer.

Seaweeds, being abundant sources of bioactive components have much interest in recent times. The complex polysaccharides from the brown, red and green seaweeds possess broad spectrum therapeutic properties. The sulfated polysaccharides are routinely used in biomedical research and have known biological activities. Fucoidan, a fucose-rich polysaccharide extracted from brown seaweed has various biological functions including anticancer effects. Cellular damage induces growth arrest and tumor suppression by inducing apoptosis, the mechanism of cell death depends on the magnitude of DNA damage following exposure to anticancer agents. Apoptosis is mainly regulated by cell growth signaling molecules. Number of research studies evidenced that fucoidan shown to induce cytotoxicity of various cancer cells, induces apoptosis, and inhibits invasion, metastasis and angiogenesis of cancer cells. There are few articles discussing on fucoidan biological activity but no specific review on cancer and its signaling mechanism. Hence, this review discusses the brown seaweed fucoidan structure and some biological function and role in apoptosis, invasion, metastasis, angiogenesis and growth signal mechanism on cancer.

RETRACTED: Marine actinobacterial metabolites: Current status and future perspectives

This article has been retracted: please see Elsevier Policy on Article Withdrawal (https://www.elsevier.com/about/our-business/policies/article-withdrawal). This article has been retracted at the request of the Editor. Authors and Editor agreed to retract this article because substantial parts of the text were copied from the following sources without proper attribution: Lam, K.S. (2006), Discovery of novel metabolites from marine actinomycetes. Current Opinion in Microbiology 9(3), pp. 245–251; Subramani, R., Aalbersberg, W. (2012), Marine actinomycetes: An ongoing source of novel bioactive metabolites. Microbiological Research 167(10), pp. 571–580; Dharmaraj, S. (2010), Marine Streptomyces as a novel source of bioactive substances. World Journal of Microbiology and Biotechnology 26(12), pp. 2123–2139. The authors apologize for this oversight and any inconvenience caused.

Biosynthesis, Antimicrobial and Cytotoxic Effect of Silver Nanoparticles Using a Novel Nocardiopsis sp. MBRC-1

The biosynthesis of nanoparticles has been proposed as a cost effective environmental friendly alternative to chemical and physical methods. Microbial synthesis of nanoparticles is under exploration due to wide biomedical applications, research interest in nanotechnology and microbial biotechnology. In the present study, an ecofriendly process for the synthesis of nanoparticles using a novel Nocardiopsis sp. MBRC-1 has been attempted. We used culture supernatant of Nocardiopsis sp. MBRC-1 for the simple and cost effective green synthesis of silver nanoparticles. The reduction of silver ions occurred when silver nitrate solution was treated with the Nocardiopsis sp. MBRC-1 culture supernatant at room temperature. The nanoparticles were characterized by UV-visible, TEM, FE-SEM, EDX, FTIR, and XRD spectroscopy. The nanoparticles exhibited an absorption peak around 420 nm, a characteristic surface plasmon resonance band of silver nanoparticles. They were spherical in shape with an average particle size of 45 ± 0.15 nm. The EDX analysis showed the presence of elemental silver signal in the synthesized nanoparticles. The FTIR analysis revealed that the protein component in the form of enzyme nitrate reductase produced by the isolate in the culture supernatant may be responsible for reduction and as capping agents. The XRD spectrum showed the characteristic Bragg peaks of 1 2 3, 2 0 4, 0 4 3, 1 4 4, and 3 1 1 facets of the face centered cubic silver nanoparticles and confirms that these nanoparticles are crystalline in nature. The prepared silver nanoparticles exhibited strong antimicrobial activity against bacteria and fungi. Cytotoxicity of biosynthesized AgNPs against in vitro human cervical cancer cell line (HeLa) showed a dose-response activity. IC50 value was found to be 200 μg/mL of AgNPs against HeLa cancer cells. Further studies are needed to elucidate the toxicity and the mechanism involved with antimicrobial and anticancer activity of the synthesized AgNPs as nanomedicine.

Marine actinobacteria: An important source of bioactive natural products

Marine environment is largely an untapped source for deriving actinobacteria, having potential to produce novel, bioactive natural products. Actinobacteria are the prolific producers of pharmaceutically active secondary metabolites, accounting for about 70% of the naturally derived compounds that are currently in clinical use. Among the various actinobacterial genera, Actinomadura, Actinoplanes, Amycolatopsis, Marinispora, Micromonospora, Nocardiopsis, Saccharopolyspora, Salinispora, Streptomyces and Verrucosispora are the major potential producers of commercially important bioactive natural products. In this respect, Streptomyces ranks first with a large number of bioactive natural products. Marine actinobacteria are unique enhancing quite different biological properties including antimicrobial, anticancer, antiviral, insecticidal and enzyme inhibitory activities. They have attracted global in the last ten years for their ability to produce pharmaceutically active compounds. In this review, we have focused attention on the bioactive natural products isolated from marine actinobacteria, possessing unique chemical structures that may form the basis for synthesis of novel drugs that could be used to combat resistant pathogenic microorganisms.

Marine polysaccharide-based nanomaterials as a novel source of nanobiotechnological applications.

Research on marine polysaccharide-based nanomaterials is emerging in nanobiotechnological fields such as drug delivery, gene delivery, tissue engineering, cancer therapy, wound dressing, biosensors, and water treatment. Important properties of the marine polysaccharides include biocompatibility, biodegradability, nontoxicity, low cost, and abundance. Most of the marine polysaccharides are derived from natural sources such as fucoidan, alginates, carrageenan, agarose, porphyran, ulvan, mauran, chitin, chitosan, and chitooligosaccharide. Marine polysaccharides are very important biological macromolecules that widely exist in marine organisms. Marine polysaccharides exhibit a vast variety of structures and are still under-exploited and thus should be considered as a novel source of natural products for drug discovery. An enormous variety of polysaccharides can be extracted from marine organisms such as algae, crustaceans, and microorganisms. Marine polysaccharides have been shown to have a variety of biological and biomedical properties. Recently, research and development of marine polysaccharide-based nanomaterials have received considerable attention as one of the major resources for nanotechnological applications. This review highlights the recent research on marine polysaccharide-based nanomaterials for biotechnological and biomedical applications.

Production of polysaccharide-based bioflocculant for the synthesis of silver nanoparticles by Streptomyces sp.

Polysaccharide-based bioflocculants have attracted considerable attention in recent years due to their biodegradable, harmless and negligible secondary pollution. Bioflocculants are organic macromolecular substances secreted by microorganisms. A simple, cost-effective and green method was developed for the biosynthesis of silver nanoparticles using polysaccharides as reducing and stabilizing agents. In this paper, we report on the production and optimization of polysaccharide-based bioflocculant for the green synthesis of silver nanoparticles by Streptomyces sp. MBRC-91. Medium composition and culture conditions for polysaccharide-based bioflocculants were statistically optimized by response surface methodology (RSM). The bioflocculant production was statistically optimized with most significant factors, namely palm jaggery (18.73g/L), yeast extract (2.07g/L), K2HPO4 (3.74g/L) and NaCl (0.38g/L), respectively. The biosynthesized silver nanoparticles were characterized by UV-vis spectroscopy, XRD, FTIR, FESEM, EDXA and HRTEM. The biosynthesized silver nanoparticles revealed strong antibacterial activity in sewage water and this result could make a new avenue in the wastewater treatment. Therefore, the biosynthesized silver nanoparticles can be extended as an alternative for the development of new bactericidal bionanomaterials for wastewater treatment and biotechnological applications.

Doxorubicin-loaded fucoidan capped gold nanoparticles for drug delivery and photoacoustic imaging.

Polymer nanoparticles are emerging as a useful tool for a wide variety of biomedical and therapeutic applications. The present study demonstrates the multifunctional doxorubicin-loaded fucoidan capped gold nanoparticles (DOX-Fu AuNPs) for drug delivery and photoacoustic imaging (PAI). Biocompatible AuNPs were synthesized using a naturally occurring fucoidan (Fu) as a capping and reducing agent. The Fu AuNPs synthesis was determined using UV-visible spectrum, and it was further characterized using high resolution transmission electron microscopy, energy dispersive X-ray spectroscopy, Fourier transform infrared spectroscopy, and X-ray diffraction analysis. The release of DOX from DOX-Fu AuNPs was greater in acidic pH (4.5) than in neutral pH (7.4). The in vitro cytotoxic effect of fucoidan, Fu AuNPs, DOX, and DOX-Fu AuNPs inhibited the proliferation of human breast cancer cells with an inhibitory concentration of 35μg/mL, 30μg/mL, 15μg/mL, and 5μg/mL at 24h. DOX-Fu AuNPs induced both early and late apoptosis in a concentration-dependent manner compared with untreated control cells. The ability of DOX-Fu AuNPs as a contrast agent for in vitro breast cancer imaging with PAI has been evaluated. These results suggest that the multifunctional DOX-Fu AuNPs for drug delivery and PAI can soon provide considerable contribution to human health.

Production of α-amylase for the biosynthesis of gold nanoparticles using Streptomyces sp. MBRC-82

Marine actinobacterial synthesis of gold nanoparticles has good potential to develop simple, cost-effective and eco-friendly methods for production of important biomaterials. In this context, gold nanoparticles have attracted considerable attention in recent years, owing to their various applications. In this paper, we report on the production of α-amylase for the extracellular synthesis of gold nanoparticles using Streptomyces sp. MBRC-82. Medium composition and culture conditions for α-amylase production were statistically optimized. Plackett-Burman design was employed to find out the optimal medium constituents and culture conditions to enhance α-amylase production. Box-Behnken design revealed that three independent variables namely soluble starch (5.8484 g), peptone (3.5191 g), and NaCl (0.3829) significantly influenced α-amylase production. The gold nanoparticles were characterized by ultraviolet-visible (UV-vis) spectrometer, X-ray diffractometer (XRD), Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), energy dispersive X-ray analysis (EDXA), and transmission electron microscopy (TEM). The particles synthesized using the optimized enzyme activity ranged from 20 to 80 nm with an average particle size of 40 nm and therefore can be extended to various medicinal applications.