Biopolymers – Application in Nanoscience and Nanotechnology

In order to reduce the use of non-renewable resources and to minimize the environmental pollution caused by synthetic materials, the quest for utilizing biomaterials is on a rise. Biopolymers in nature are produced by a range of microorganisms and plants. Biopolymers produced by microorganisms require specific nutrients and controlled environmental conditions. This chapter discusses the recent developments and trends of biopolymers especially in the field of nanotechnology. A basic introduction regarding biopolymers is included at the beginning of the chapter. A detailed discussion on various characterization techniques used for characterizing biopolymers and various frequently used biopolymers is also included. Applications of biopolymers in various fields, especially in the field related to nanoscience and nanotechnology, is elaborated at the end of the chapter. Biopolymers together with nanotechnology have already found many applications in various fields including water treatment, biomedical application, energy sector, and food industry. This chapter is intended to give an overview on the importance of biopolymers in nanotechnology-based applications

Biopolymer-mediated Green Synthesis of Noble Metal Nanostructures

Polymer-coated noble metal nanoparticles are currently of particular interest to investigators in the fields of nanobiomedicine and fundamental biomaterials. These materials not only exhibit imaging properties in response to stimuli but also efficiently deliver various drugs and therapeutic genes. Even though a large number of polymer-coated noble metal nanoparticles have been fabricated over the past decade, most of these materials still present some challenges emanating from their synthesis. The metal nanoparticles when encapsulated in a polymer and taken up by human cells might show a lower degree of toxicity; however, the degree of toxicity for some of the starting materials and precursors has raised serious concerns. Hence, there is a need to implement the principle of green chemistry in the synthesis of nanomaterials. The use of environmentally benign materials for the synthesis of metal nanoparticles provides numerous benefits ranging from biocompatibility, availability, cost-effectiveness, amenable scale-up to eco-friendliness. The biopolymer-based nanovehicles have been found to be more suitable in the field of nanotechnology owing to their high reproducibility, ease of manufacture, functional modification and safety (they are not carcinogenic). Unlike synthetic polymers where the raw material can be derived from petrochemicals or chemical industrial processes, biopolymers are produced from renewable resources such as plant and/or living organism. They are degradable by natural processes down to elemental entities that can be resorbed in the environment. Furthermore, they can also be modified to serve a particular purpose which explains the myriad of their potential applications. The macromolecular chain of these biopolymers possesses a large number of hydroxyl groups which can easily complex with metal ions. Additionally, these biopolymers also contain supramolecular structures that can lead to new functionalities of their composites with metal and semiconductor nanoparticles. In this chapter, a comprehensive discussion on different biopolymers, green synthesis of noble metal nanostructures, mechanisms, characterization and application in various fields is presented

Sugarcane Bagasse and Cellulose Polymer Composites

Waste recycling has been the main topic of various scientific researches due to environmental management. Renewable agricultural sources such as pineapple leaf, sisal, jute, piassava, coir, and sugarcane bagasse are among agro waste, normally known as biomass, which is recently used for reinforcing polymeric materials. Sugarcane bagasse fiber residues has been extensively investigated and employed as a source of reinforcement of polymers. The major residue is normally burnt for energy supply in the sugar and alcohol industries and as a result, tons of ash is created. The ash contained inorganic components which are valuable for reinforcement in polymeric materials. This chapter reports on the use of sugarcane bagasse, sugarcane bagasse ash (SBA) and its cellulose as reinforcing fillers for polymers

Chemical and biological studies of Lobelia flaccida (C. Presl) A.DC leaf: a medicinal plant used by traditional healers in Eastern Cape, South Africa

Purpose: To investigate the phytochemical constituents, acute toxicity and biological activities of Lobelia herb (dried leaf of Lobelia flaccida; family: Campanulaceae), a popular medicinal agent used to manage pain and epilepsy among other indications in Eastern Cape Region of South Africa.Methods: Essential oil (EO) obtained from the dried leaf was analysed with gas chromatography-mas spectroscopy GC/MS while an infusion extract of the herb was obtained by soaking in hot boiled water (100 oC) for 24 h, filtered and the filtrate dried in vacuo. Phytochemical screening of the infusion extract was performed to detect the presence of secondary plant metabolites and relative abundance of some of the metabolites. The aqueous extract was evaluated for oral (p.o.) acute toxicity (LD50) using the Lorke’s method [30];, thereafter the extract was tested for anti-inflammatory activity on carrageenaninduced rat paw oedema at 250 and 500 mg/kg, p.o., normal saline and aspirin (100 mg/kg, p.o.) used as negative and positive controls respectively. Finally, the extract at 500 and 1000 mg/kg, p.o. was tested for anticonvulsant activity on pentylene tetrazol (85 mg/kg, intraperitoneally)-induced convulsion model in mice, normal saline and diazepam (1 mg/kg, i.p.) served as negative and positive control groups respectively.Results: EO yield was 0.022 % w/w and the two major compounds identified were acetophenone (26.37 %) and caryophyllene (17.35 %). Phytochemical screening showed high concentration of alkaloids, saponins and flavonoids among other constituents. LD50 of the aqueous extract was ≥ 5000 mg/kg per oral while the aqueous extract exhibited significant (p < 0.01) anti-inflammatory activity on carrageenan-induced rat paw oedema comparable to aspirin but insignificant anticonvulsant activity on pentylene tetrazol-induced convulsion when compared with diazepam.Conclusion: Lobelia herb is non-toxic, and possesses significant anti-inflammatory and mild anticonvulsant activities. It is suggested that the essential oil of this herb should be screened for pharmacological activities.Keywords: Lobelia flaccida, Essential oil, Gas chromatography/mass spectroscopy analysis , Infusion extract, Acute toxicity, Anti-inflammatory, Anti-convulsan

Size tunable synthesis of monodispersed hexadecylamine-capped CdSe nanostructures

We herein report the synthesis of high quality hexadecylamine (HDA)-capped CdSe nanostructures via a facile and effective non-organometallic method. By varying the growth temperature we monitored the size, optical properties and morphology of the as-synthesised CdSe nanoparticles. The nanoparticles were characterised using UV–vis absorption and photoluminescence (PL) spectroscopy, Fourier transform infrared spectroscopy (FTIR), x-ray diffraction (XRD), transmission electron spectroscopy (TEM), high resolution electron transmission microscopy (HRTEM) and energy dispersive spectroscopy (EDS). The nanoparticles obtained were of high quality and monodispersed with high absorption and emission features. The emission and absorption maxima of the as-synthesised materials were red-shifted as the growth temperature increased indicating increase in particle size. The XRD analysis showed phase transition from cubic to hexagonal while the TEM images consist of both spherical and elongated particles as the temperature increased from 110 1C to 200 1C. The FTIR spectra confirmed the capping of the as-synthesised material by HDA while the EDS confirmed the presence of the corresponding elements.This work was supported by National Research Foundation (NRF), South Africa

Encapsulation of Gold Nanorods with Porphyrins for the Potential Treatment of Cancer and Bacterial Diseases: A Critical Review

Cancer and bacterial diseases have been the most incidental diseases to date. According to the World Health Report 2018, at least every family is affected by cancer around the world. In 2012, 14.1 million people were affected by cancer, and that figure is bound to increase to 21.6 million in 2030. Medicine therefore sorts out ways of treatment using conventional methods which have been proven to have many side effects. Researchers developed photothermal and photodynamic methods to treat both cancer and bacterial diseases. These methods pose fewer effects on the biological systems but still no perfect method has been synthesized. The review serves to explore porphyrin and gold nanorods to be used in the treatment of cancer and bacterial diseases: porphyrins as photosensitizers and gold nanorods as delivery agents. In addition, the review delves into ways of incorporating photothermal and photodynamic therapy aimed at producing a less toxic, more efficacious, and specific compound for the treatment

Size tunable synthesis of HDA and TOPO capped ZnSe nanoparticles via a facile aqueous/thermolysis hybrid solution route

We herein report the synthesis of hexadecylamine (HDA) and trioctylphosphine (TOPO) capped ZnSe nanoparticles (NPs) via a simple and environmentally benign aqueous/thermolysis hybrid solution route. The synthesis involves the use of cheap and less toxic precursors as starting materials. By varying the reaction temperature, monomer concentration, capping group and zinc precursor we systematically studied the size, optical and structural properties of the as-synthesised NPs. The NPs were characterised using UV–Vis absorption and photoluminescence spectroscopy, transmission electron microscopy, high resolution transmission electron microscopy (HRTEM) and X-ray diffraction (XRD). All the particles exhibited strong quantum confinement with respect to the bulk ZnSe. The absorption and emission maxima of the TOPO-capped ZnSe NPs are blue-shifted, as compared to the HDA-capped NPs synthesized at the same temperature and monomer concentration. The use of Zn(CH3COO)2 as the precursor resulted in a smaller NPs with no evidence of trap emission. The HRTEM confirm the crystallinity of the material while the XRD results indicated that the capping group has no pronounced effect on the phase and crystalline structure of the as-synthesised ZnSe NPs.National Research Foundation (NRF), South Africa. South Africa under the Nanotechnology Flagship Programme (Grant No. 97983