Part of the book: Products and Applications of Biopolymers
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.
Part of the book: Recent Advances in Biopolymers
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.
Part of the book: Recent Advances in Biopolymers
Quantum dots (QDs), because of their exciting optical properties, have been explored as alternative fluorescent sensors to conventional organic fluorophores which are routinely employed for the detection of various analytes via fluorometry. QD probes can detect toxic metal ions, anions, organic molecules with good selectivity and sensitivity. This chapter investigates the synthesis of Mn-doped ZnSe QDs using nucleation-doping strategy. The as-synthesized QDs were characterized by various analytical tools such as ultraviolet-visible (UV-vis) absorption, photoluminescence (PL) spectroscopy, X-ray diffractometry (XRD) and transmission electron microscopy (TEM). It was found that Mn doping of QDs significantly increases the PL intensity. The PL of the resulting QDs was examined in the presence of different metal ions to check its selective response. Among the various metal ions, Hg2+ exhibits a drastic quenching of the QD’s emission intensity. A Stern-Volmer plot of [Hg2+] sensing using the as-synthesized QDs showed linearity in the range of 0–30 × 10−6 ML−1 with the regression coefficient R2 = 0.99. The detection limit was found to be 6.63 × 10−7 ML−1. Thus, the present Mn-doped ZnSe QDs represent a simple, non-toxic fluorescent probe for the qualitative and quantitative detection of mercury ions in aqueous samples.
Part of the book: Nonmagnetic and Magnetic Quantum Dots